A display system and a display method

Abstract

The application discloses a display system and a display method. The display system comprises a liquid crystal modulation assembly and an image processor. The liquid crystal modulation assembly is used for modulating first light source light based on a digital modulation signal to obtain image light. The frame period of each frame of digital modulation signal comprises a plurality of pixel frame periods. The pixel frame period comprises a plurality of PWM periods. Each frame of digital modulation signal comprises a plurality of pixel frame modulation signals corresponding to the pixel frame periods. Each pixel frame modulation signal comprises a plurality of PWM signals, and each PWM signal corresponds to a PWM period. The image processor is used for determining the waveform of the pixel frame modulation signal of the current pixel frame period based on the image data of the previous pixel frame period and the image data of the current pixel frame period in the two continuous pixel frame periods. In the above manner, the application can shorten the switching time of the liquid crystal, improve the display quality, and avoid the problems of liquid crystal durability and system complexity caused by voltage overdrive.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a display system and display method. Background Technology

[0002] To address the technical issue of incorrect grayscale display caused by the slow rotation of liquid crystal (LC) molecules, an overdrive (OD) technique can be employed to correct the grayscale of LC molecules. When transitioning from one frame to the next, a preset second lookup table is consulted based on the frame information of the previous frame to obtain the actual grayscale value of that frame. Then, based on the actual grayscale value of the previous frame and the predetermined grayscale value of the next frame, a preset first lookup table is consulted to obtain the overdrive grayscale value used for grayscale conversion. Finally, overvoltage driving is applied based on the overdrive grayscale value, which can prevent improper operation from affecting the display effect. However, because it requires adjustment of grayscale or voltage values, implementation is relatively complex, and frequent overdrive may damage the liquid crystal layer due to excessively high voltage. Summary of the Invention

[0003] This application provides a display system and display method that can shorten the switching time required for the liquid crystal to switch from the previous grayscale value to the current grayscale value, improve display quality, and avoid the problems of liquid crystal durability and system complexity caused by voltage overdrive.

[0004] To address the aforementioned technical problems, this application provides a display system comprising: a liquid crystal modulation component and an image processor. The liquid crystal modulation component is used to modulate a first light source based on a digital modulation signal to obtain image light. The frame period of each frame of the digital modulation signal includes multiple pixel frame periods, each pixel frame period includes multiple PWM periods, each frame of the digital modulation signal includes multiple pixel frame modulation signals corresponding to the pixel frame periods, and each pixel frame modulation signal includes multiple PWM signals, with each PWM signal corresponding one-to-one with a PWM period. The image processor is used to determine the waveform of the pixel frame modulation signal of the current pixel frame period based on the image data of the previous pixel frame period and the image data of the current pixel frame period.

[0005] In one implementation, the duration of each PWM cycle is equal, and the waveform of the PWM signal corresponding to a single pixel contains at most one high level and one low level.

[0006] In one implementation, during a pixel frame period, when the gray value of a pixel is less than a preset gray value, the waveform of the first PWM signal in the pixel frame modulation signal corresponding to that pixel starts at a low level and ends at a high level; when the gray value of the pixel is greater than or equal to the preset gray value, the waveform of the first PWM signal in the pixel frame modulation signal corresponding to that pixel starts at a high level and ends at a low level.

[0007] In one embodiment, the pixel frame modulation signal includes, in a timing sequence, at least a first PWM signal group for satisfying the liquid crystal response requirement and a second PWM signal group for satisfying the grayscale requirement. The first PWM signal group includes at least one PWM cycle, the time corresponding to the first PWM signal group is greater than the liquid crystal response time, and the difference between the time corresponding to the first PWM signal group and the liquid crystal response time is less than the time of one PWM cycle. Within one pixel frame cycle, there exists at least a first grayscale range such that when the grayscale value of a pixel is within the first grayscale range, the waveforms of the PWM signals of the first PWM signal group and the PWM signals of the second PWM signal group corresponding to that pixel are different.

[0008] In one embodiment, the multiple pixel frame cycles include a red pixel frame cycle, a green pixel frame cycle, and a blue pixel frame cycle. The duration of the green pixel frame cycle is longer than that of the red pixel frame cycle, and the duration of the red pixel frame cycle is longer than that of the blue pixel frame cycle. The red pixel frame cycle, the green pixel frame cycle, and the blue pixel frame cycle together comprise 6 to 15 PWM cycles.

[0009] In one embodiment, a light source is used to generate second light source light; a wavelength conversion device is disposed in the optical path of the second light source light to process the second light source light to obtain first light source light; wherein, the wavelength conversion device includes multiple color partitions, the multiple color partitions including a red light conversion area, a green light conversion area and a scattering area disposed along a ring direction, for sequentially generating red fluorescence, green fluorescence and blue light.

[0010] In one implementation, the angle of the color partition is an integer multiple of a preset angle, and the duration of the PWM cycle is an integer multiple of the duration corresponding to the preset angle.

[0011] In one embodiment, the multiple color partitions further include a first blank area, a second blank area, and a third blank area, in which the light source is in a turned-off state; the first blank area is located between the red light conversion area and the green light conversion area, the second blank area is located between the green light conversion area and the scattering area, and the third blank area is located between the scattering area and the red light conversion area; wherein, the angles of the first blank area, the second blank area, and the third blank area are related to the liquid crystal response time of the liquid crystal modulation component.

[0012] In one embodiment, the display system further includes a storage device for storing a lookup table that establishes a relationship between image data from two consecutive pixel frame periods and the waveform of the pixel frame modulation signal in the current pixel frame period.

[0013] The present invention also provides a display method applied to the aforementioned display system. The method includes: controlling an image processor to determine the waveform of a pixel frame modulation signal for the current pixel frame period based on image data from the previous pixel frame period and image data from the current pixel frame period, wherein the frame period corresponding to the digital modulation signal includes multiple pixel frame periods, each pixel frame period includes multiple PWM periods, each frame digital modulation signal includes multiple pixel frame modulation signals corresponding to the pixel frame period, and each pixel frame modulation signal includes multiple PWM signals, with each PWM signal corresponding one-to-one with a PWM period; and controlling a liquid crystal modulation component to modulate the light from a first light source based on the digital modulation signal to obtain image light.

[0014] The beneficial effects of this application through the above scheme are as follows: By using the image data of the current pixel frame period and the image data of the previous pixel frame period to determine the waveform of the pixel frame modulation signal of the current pixel frame period, the time for resetting the position of liquid crystal molecules in the previous pixel frame period and starting the deflection of liquid crystal molecules in the current pixel frame period is saved. This makes the modulation of liquid crystal molecules in adjacent pixel frame periods have a certain continuity, which can shorten the switching time required for the liquid crystal to switch from the previous gray value to the current gray value, speed up the response speed of the liquid crystal, and prevent the LC molecules from rotating to the angle corresponding to the next gray value for a long time due to the excessive LC response time. This improves the color crosstalk problem between adjacent pixel frames and helps to improve the display quality. Moreover, this driving method is implemented by controlling the waveform of the pixel frame period signal, without overdriving. On the one hand, it avoids damage to the liquid crystal layer caused by excessive voltage, and on the other hand, it does not require memory storage of the actual driving voltage of "overdriving", making it simple to implement. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0016] Figure 1 This is a schematic diagram of the structure of an embodiment of the display system provided in this application;

[0017] Figure 2 This is a schematic diagram of the digital modulation signal provided in this application;

[0018] Figure 3 This is a schematic diagram of another embodiment of the display system provided in this application;

[0019] Figure 4(a) is a schematic diagram of the wavelength conversion device provided in this application;

[0020] Figure 4(b) is another structural schematic diagram of the wavelength conversion device provided in this application;

[0021] Figure 5 This is another structural schematic diagram of the wavelength conversion device provided in this application;

[0022] Figure 6 This is a schematic diagram of the three frame pixel periods provided in this application;

[0023] Figure 7(a) is a schematic diagram of the digital modulation signal provided in this application when the gray value is switched from 63 to 191;

[0024] Figure 7(b) is a schematic diagram of the digital modulation signal provided in this application when the gray value is switched from 191 to 223;

[0025] Figure 8 This is a flowchart illustrating an embodiment of the display method provided in this application. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] Please see Figure 1 , Figure 1 This is a schematic diagram of an embodiment of the display system provided in this application. The display system includes: a light source 10, a wavelength conversion device 20, a liquid crystal modulation component 30, and an image processor 40. The light emitted by the light source 10 passes through the wavelength conversion device 20 to form illumination light for the liquid crystal modulation component 30. The liquid crystal modulation component 30 modulates the illumination light under the control of the input signal from the image processor 40 to obtain image light.

[0028] The light source 10 is used to generate the second light source light; specifically, the light source 10 can be a pure laser light source or a laser fluorescence light source. For example, the light source 10 is a blue laser, and the second light source light it generates is blue laser light.

[0029] The wavelength conversion device 20 is disposed in the optical path of the second light source and is used to process the second light source to obtain the first light source. Specifically, the wavelength conversion device 20 can be a fluorescent color wheel, and the first light source can be a timed laser and / or fluorescence.

[0030] In one specific embodiment, the wavelength conversion device 20 includes multiple color zones (not shown in the figure), each color zone including multiple sub-regions (not shown in the figure); further, the multiple color zones include a wavelength conversion region and a scattering region. Taking blue laser light as the second light source as an example, the blue laser light is used as the excitation light and is incident on the wavelength conversion region of the wavelength conversion device 20. The wavelength conversion region contains a wavelength conversion material capable of wavelength conversion. The wavelength conversion material receives the blue laser light and emits a received laser light with a wavelength different from the blue laser light to the liquid crystal modulation component 30. This received laser light can be fluorescence. The wavelength conversion material can be quantum dots or phosphor materials, etc. This embodiment uses phosphor materials as an example. Different colored phosphor materials can emit fluorescence of corresponding colors under the excitation of blue laser light. The phosphor materials in this embodiment may include yellow phosphor materials, red phosphor materials, or green phosphor materials, etc., and the color zones include a red light conversion region, a green light conversion region, and a scattering region.

[0031] Understandably, the luminous intensity of the light source 10 can be different for different color zones. Taking the light source 10 as a blue laser as an example, the luminous intensity of the blue laser can be adjusted when the wavelength conversion device 20 rotates at different angles. For example, in the wavelength conversion zone, the luminous intensity of the blue laser is L1, and in the scattering zone, the luminous intensity of the blue laser is L2, so that the combined light of red, green and blue light in one cycle satisfies white balance.

[0032] The aforementioned light source 10 and wavelength conversion device 20 can be considered as a whole, serving as the illumination source module of the display system. The first light source can also be referred to as the illumination light of the display system (corresponding to the emitted image light). This illumination source module can be replaced with a light-emitting diode (LED) light source module, etc.

[0033] The liquid crystal modulation component 30 is used to modulate the first light source light based on a digital modulation signal to obtain image light. Specifically, the liquid crystal modulation component 30 can be a reflective liquid crystal spatial light modulator or a transmissive liquid crystal spatial light modulator, such as a liquid crystal display (LCD) or a liquid crystal on silicon (LCoS).

[0034] In this invention, the first light source is temporally synthesized colored light, and the color image is composed of temporally superimposed monochrome images. For each frame of digital modulation signal, its frame period includes multiple pixel frame periods (a pixel frame represents a color channel of a single frame), and each frame of digital modulation signal includes multiple pixel frame modulation signals corresponding to the pixel frame periods (i.e., modulation signals for a single color channel). Each frame of digital modulation signal modulates one frame of color image, and each pixel frame modulation signal modulates the monochrome image contained within one frame of color image.

[0035] In this invention, the image processor 40 determines the waveform of the pixel frame modulation signal for the current pixel frame period based on the image data of the previous pixel frame period and the image data of the current pixel frame period. Specifically, the image data (including the image data of the previous frame and the image data of the current frame) includes the grayscale value of each pixel in each frame of the video to be displayed. For color images, there are generally three color channels: red, green, and blue. Therefore, multiple pixel frame periods include red pixel frame periods, green pixel frame periods, and blue pixel frame periods, and the durations of these three pixel frame periods can be the same or different. If the RGB (red-green-blue) sequence is followed, then when the green channel image needs to be modulated, the image processor 40 determines the waveform of the green pixel frame modulation signal for the current frame based on the image data of the red pixel frame period and the image data of the green pixel frame period of the current frame; when the red channel image needs to be modulated, the image processor 40 determines the waveform of the red pixel frame modulation signal for the current frame based on the image data of the blue pixel frame period of the previous frame and the image data of the red pixel frame period of the current frame.

[0036] Understandably, multiple pixel frame periods can also take other forms, and are not limited to the multiple pixel frame periods provided in this embodiment, which include red pixel frame periods, green pixel frame periods, and blue pixel frame periods. They can be set according to specific application needs. The color partitions on the wavelength conversion device 20 can be 3, 4, or more. For example, if the wavelength conversion device 20 is provided with 4 color partitions: RGBY (red, green, blue, yellow) or RGBW (red, green, blue, white), then the multiple pixel frame periods include red pixel frame periods, green pixel frame periods, blue pixel frame periods, and yellow / white pixel frame periods.

[0037] Furthermore, in this invention, each pixel frame period includes multiple pulse width modulation (PWM) periods, and each pixel frame modulation signal includes multiple PWM signals, with each PWM signal corresponding to a PWM period. Since liquid crystal molecules naturally have a slow response speed (corresponding to the metal mirror of a Digital Micromirror Device (DMD), by dividing the pixel frame period of a monochrome channel into multiple small PWM periods, digital modulation of the liquid crystal can be performed in each PWM period, and the modulation of each PWM period is independent. Compared with existing solutions, the modulation time period is shortened, and the waveform changes of the digital modulation signal within a frame period are more varied. This avoids the voltage difference between two adjacent pixels in the liquid crystal modulation component 30 from remaining at a high level for a long time, and avoids the digital modulation signal level from remaining at a fixed level (i.e., high or low level) for a long time. This improves crosstalk between adjacent pixels or adjacent image frames, thereby improving display quality.

[0038] The PWM signal corresponds to a ONE-ON-ONE-OFF modulation waveform for a single pixel, containing at most one high level and one low level (including the cases where all low levels are for the darkest and brightest pixels, and all high levels are for the brightest pixels). Combining this modulation waveform with "dividing a single pixel frame period into multiple PWM cycles" balances computational resources, LCD response speed, and display quality.

[0039] Within a PWM cycle, the liquid crystal modulation component 30 can modulate a fixed set of pixel data to refresh the display screen; and the time difference between the duration of one PWM cycle and the LC response time of the liquid crystal modulation component 30 is less than a preset value, which is a value set based on experience or application requirements. Preferably, the duration of one PWM cycle is equal to the LC response time, but in reality, due to the influence of multiple factors such as materials, liquid crystal layer thickness, and temperature on the LC response time, it is difficult to achieve a perfect equality between the two; generally, an LC response time with a time difference of less than 10% is preferable. In other embodiments of the present invention, there may also be a case where multiple PWM cycles correspond to the LC response time, for example, the duration of two PWM cycles matches the LC response time.

[0040] In some specific embodiments of the present invention, the duration of each PWM cycle is equal, which makes it more convenient to set the clock cycle for modulating and refreshing the PWM cycle, which helps to make the whole design simpler, optimize the execution efficiency of the driver chip, and directly affect the cost and power consumption of the driver chip.

[0041] In other specific embodiments of the invention, the display system further includes a storage device (not shown) for storing a lookup table that establishes the relationship between image data of two consecutive pixel frame periods and the waveform of the pixel frame modulation signal of the current pixel frame period. The image processor 40 is used to determine the waveform of the digital modulation signal based on the image data of the previous pixel frame period, the image data of the current pixel frame period, and the lookup table.

[0042] A lookbehind transitional look-up table-based driving method can be used. The grayscale value of a pixel in the current pixel frame image data is recorded as the current grayscale value, and the grayscale value in the previous pixel frame image data that is at the same position as the current grayscale value is recorded as the previous grayscale value. Using the previous grayscale value, the current grayscale value, and the lookup table, the waveform of the digital modulation signal required for the normal display of that pixel is calculated. This method is called Binary Rudder, and it can speed up the time required for the liquid crystal to switch from the previous grayscale value to the current grayscale value.

[0043] Furthermore, the size of the lookup table can be 256 bytes × 256 bytes, and the storage device can be static random access memory (SRAM).

[0044] In one specific embodiment, each pixel frame period includes 4 PWM periods. Within the same monochrome frame, the waveform of the digital modulation signal corresponding to the first PWM period is to meet the requirements of the liquid crystal response. Starting from the second PWM period, the waveform of the corresponding digital modulation signal is fixed to meet the grayscale requirements. The specific waveform of the digital modulation signal can be an empirical value obtained by repeated experiments on the characteristics of the liquid crystal material.

[0045] In one specific implementation, it is assumed that a frame period contains n PWM cycles. The number of PWM cycles in the red pixel frame period, the number of PWM cycles in the green pixel frame period, and the number of PWM cycles in the blue pixel frame period for each pixel are denoted as nr, ng, and nb, respectively. When a frame period only includes the red pixel frame period, the green pixel frame period, and the blue pixel frame period, n = nr + ng + nb. n is related to the LC response time. The larger n is, the better the alignment with the LC response time, and the better the display quality. Moreover, the fastest clock frequency in the liquid crystal modulation component 30 is proportional to n.

[0046] ClkTICK = Number of PWM cycles per frame × Frame rate × Number of gray levels × Number of image lines. For an 8-bit binary data image, the number of gray levels is 256. The typical display image frame rate is 60Hz, and the high frame rate image frame rate is 120Hz.

[0047] When n=12, the clock frequencies of different types of liquid crystal modulation components 30 are as follows:

[0048] 1) For the 720p liquid crystal modulation component 30, the clock frequency is as follows:

[0049] ClkTICK=12×60Hz×256ticks×720rows=132.7MHz

[0050] 2) For the 1080p liquid crystal modulation component 30, the clock frequency is as follows:

[0051] ClkTICK=12×60Hz×256ticks×1080rows=199.1MHz

[0052] Therefore, although theoretically a larger n is better, a clock frequency of 199.1MHz is already close to the speed limit of current manufacturing processes, so the value of n is limited. In this embodiment, when the number of PWM cycles in each pixel frame period is the same, i.e., nr = ng = nb, the number of PWM cycles in each pixel frame period can be set to 2 to 5, that is, each frame period includes 6 to 15 PWM cycles. When pixel frame periods of different colors have different numbers of PWM cycles, the number of PWM cycles contained in a frame period is also preferably 6 to 15. On the one hand, this ensures that each pixel frame period includes at least 2 PWM cycles, and on the other hand, it avoids that too many PWM cycles will cause excessive clock frequency load. For example, if a frame period includes red, green, and blue pixel frame periods, then the red pixel frame period, green pixel frame period, and blue pixel frame period together contain 6 to 15 PWM cycles.

[0053] For ease of description, the following example illustrates this solution using the example that each pixel frame cycle includes 4 PWM cycles. This invention is not intended to limit the technical solution.

[0054] like Figure 2 As shown, it illustrates the waveform of the digital modulation signal corresponding to a pixel frame (i.e., an R frame, B frame, or G frame in a color image). One PWM cycle consists of 8 segments. This is just an example; the actual settings can be adjusted according to specific application needs. For example, for RGB888 format video, which corresponds to 8 bits of binary data, each PWM cycle can be designed as 256 segments.

[0055] When the input image is transmitted at a rate of 60 frames per second, and projected in field-sequential color, the frame period is 16.6 ms. The average time allocated to each pixel frame is as follows:

[0056] 1 second / (60Hz * 3 color channels) = 5.56ms

[0057] The duration of each PWM cycle is as follows:

[0058] 1 second / (60Hz * 3 color channels * 4 PWM cycles) = 1.39ms

[0059] Therefore, the PWM cycle length is 1.39ms, while the LC response time is approximately 1.5ms, making the PWM cycle length and LC response time quite close. It is understood that this invention is not limited to... Figure 2 The duration of the PWM cycle shown is less than the LC response time, or it can be greater than the LC response time; and after the LC response time, the liquid crystal enters a relatively stable state.

[0060] To achieve coordinated operation between the Quadruple Frame Mode PWM (QPWM) and the wavelength conversion device 20, the rotation speed of the wavelength conversion device 20 is set to 60 revolutions per second, and the wavelength conversion device 20 is divided into sub-regions of 5° each. The time length corresponding to each 5° sub-region is 1s / 60rps / (360° / 5°) = 0.23ms.

[0061] The above embodiments divide the pixel frame period of a monochrome frame into n PWM cycles for digital modulation of the liquid crystal. With the same liquid crystal material, this optimizes the liquid crystal's response time, accelerating the switching time required for the liquid crystal to transition from the previous grayscale value to the current grayscale value. Furthermore, since the waveform of the digitally modulated signal is adjusted, there is no need to adjust the grayscale value / voltage value, simplifying implementation. Because the human eye has varying sensitivities to different colors, with green being the most sensitive, and sensitivity can be perceived as brightness, green significantly influences the human eye's perception of brightness. When green cannot be projected at a large scale, the perceived overall brightness is lower. Therefore, in other embodiments of the present invention, the duration of each pixel frame period is customized. Users can set a longer green pixel frame period, thereby enhancing the human eye's perception of brightness, making the displayed image appear brighter overall, thus improving display quality. Furthermore, no new hardware structure is required. Only logical operation design of the hardware structure and clock frequency design based on the expected maximum computing speed are needed. It is easy to implement and more flexible. The appropriate PWM cycle duration can be selected based on the LC response time to obtain n. Therefore, the computational complexity is low, and ultimately, good display quality and computational efficiency are achieved with minimal computing resources.

[0062] Please see Figure 3 , Figure 3This is a schematic diagram of another embodiment of the display system provided in this application. The display system includes: a light source 10, a wavelength conversion device 20, a liquid crystal modulation component 30, and an image processor 40.

[0063] Light source 10 is used to generate a second light source, which is a blue laser.

[0064] A wavelength conversion device 20 is disposed in the optical path of the light source and is used to process the second light source light to obtain the first light source light. Specifically, the wavelength conversion device 20 includes multiple color partitions (not shown in the figure), and each color partition includes multiple sub-regions (not shown in the figure).

[0065] In one specific embodiment, such as Figure 3 As shown, multiple color partitions include a red light conversion zone 212, a green light conversion zone 213, and a scattering zone 211 arranged along the annular direction, for sequentially generating red fluorescence, green fluorescence, and blue light.

[0066] Furthermore, the red light conversion region 212 is used to convert blue laser light into red fluorescence and transmit it to the liquid crystal modulation component 30; the green light conversion region 213 is used to convert blue laser light into green fluorescence and transmit it to the liquid crystal modulation component 30; and the scattering region 211 is used to scatter the blue laser light and direct it into the liquid crystal modulation component 30. Specifically, the angles of each color zone—the red light conversion region 212, the green light conversion region 213, and the scattering region 211—are integer multiples of a preset angle, and the duration of the PWM cycle is an integer multiple of the duration corresponding to the preset angle.

[0067] Understandably, in addition to setting the wavelength conversion device 20 to three color zones, four color zones can also be set according to application needs, such as RGBY. ​​Furthermore, the modulation method used in this embodiment can also be applied to other lighting sources, such as optical structures with white light sources and filter wheels, where the filter wheel includes three RGB segments or four RGBW / RGBY segments, etc.

[0068] In other embodiments, such as Figure 3 As shown, the wavelength conversion device 20 also includes a carrier substrate 22, which is used to support multiple color zones. The carrier substrate 22 can be ceramic or metal, etc. If the wavelength conversion device 20 is a transmissive color wheel, the carrier substrate 22 can also be a transparent substrate such as glass or sapphire.

[0069] The image processor 40 is used to determine the waveform of the digital modulation signal based on the image data of the previous frame and the image data of the current frame. The frame period of the digital modulation signal includes multiple pixel frame periods, and each pixel frame period includes multiple PWM periods.

[0070] Continue reading Figure 3The display system also includes a synchronization control device 50, which is connected to the light source 10, the wavelength conversion device 20, and the liquid crystal modulation component 30. The synchronization control device 50 is used to control the synchronization of the light source 10, the wavelength conversion device 20, and the liquid crystal modulation component 30. Specifically, the synchronization control device 50 includes a driver chip (not shown in the figure), which sends signals to the light source 10, the wavelength conversion device 20, and the liquid crystal modulation component 30 to synchronize them. This ensures that when the blue laser emitted by the light source 10 is incident on the red light conversion region 212 to generate red fluorescence, the liquid crystal modulation component 30 receives the digital modulation signal corresponding to the red fluorescence and the red pixel frame, processes it, and generates red image light; when the blue laser emitted by the light source 10 is incident on the green light conversion region 213 to generate green fluorescence, the liquid crystal modulation component 30 receives the digital modulation signal corresponding to the green fluorescence and the green pixel frame, processes it, and generates green image light; and when the blue laser emitted by the light source 10 is incident on the scattering region 211, the liquid crystal modulation component 30 receives the digital modulation signal corresponding to the blue light and the blue pixel frame, processes it, and generates blue image light.

[0071] Continue reading Figure 3 The display system also includes a second optical device 60 and a first optical device 70. The second optical device 60 is disposed in the output light path of the wavelength conversion device 20, and can process the laser light (including red fluorescence and green fluorescence) and blue light, and send the processed light into the liquid crystal modulation component 30. The first optical device 70 is disposed in the output light path of the liquid crystal modulation component 30, and can process and output the image light. The second optical device 60 and the first optical device 70 can be optical elements such as relay lenses or lenses.

[0072] In another specific embodiment, such as Figures 4(a)-4(b) As shown, the multiple color partitions also include a first blank area 214, a second blank area 215, and a third blank area 216. The first blank area 214 is located between the red light conversion area 212 and the green light conversion area 213. The second blank area 215 is located between the green light conversion area 213 and the scattering area 211. The third blank area 216 is located between the scattering area 211 and the red light conversion area 212. In the first blank area 214, the second blank area 215, and the third blank area 216, the light source 10 is in the off state. That is, when the first blank area 214 / the second blank area 215 / the third blank area 216 corresponds to the emission direction of the light source 10, the light source 10 does not emit light.

[0073] Furthermore, the angles of the first blank area 214, the second blank area 215, and the third blank area 216 are related to the LC response time of the liquid crystal modulation component 30. Specifically, the angles of the three blank areas (including the first blank area 214, the second blank area 215, and the third blank area 216) are equal, and the time taken for the wavelength conversion device 20 to rotate through the blank area is close to the LC response time. For example, the angle of the blank area can correspond to one PWM cycle, that is, within the time interval of one PWM cycle, the wavelength conversion device 20 rotates by the angle corresponding to the blank area.

[0074] The angle of the green light conversion region 213 is greater than the angle of the red light conversion region 212, and the angle of the red light conversion region 212 is greater than the angle of the scattering region 211. For example, the angle of the scattering region 211 is 60°. In Figure 4(a), the angle of the red light conversion region 212 is 90°, the angle of the green light conversion region 213 is 120°, and the angles of the first blank region 214, the second blank region 215, and the third blank region 216 are all 30°. In Figure 4(b), the angle of the scattering region 211 is 40°, the angle of the red light conversion region 212 is 80°, the angle of the green light conversion region 213 is 180°, and the angles of the first blank region 214, the second blank region 215, and the third blank region 216 are all 20°.

[0075] In yet another specific embodiment, such as Figure 5 As shown, the multiple color zones also include multiple buffer zones (not marked in the figure). The buffer zones are located between the red light conversion zone 212 and the third blank zone 216, between the green light conversion zone 213 and the first blank zone 214, between the green light conversion zone 213 and the second blank zone 215, between the scattering zone 211 and the second blank zone 215, or between the scattering zone 211 and the third blank zone 216. In each buffer zone, the light source 10 is in the off state.

[0076] Furthermore, the multiple buffers include a first red light buffer 217a, a second red light buffer 217b, a first green light buffer 218a, a first green light buffer 218a, a first blue light buffer 219a, and a second blue light buffer 219b; in the first red light buffer 217a, the second red light buffer 217b, the first green light buffer 218a, the first green light buffer 218a, the first blue light buffer 219a, and the second blue light buffer 219b, the light source 10 is in an off state.

[0077] The first red light buffer zone 217a is disposed between the red light conversion zone 212 and the first blank zone 214, and the second red light buffer zone 217b is disposed between the red light conversion zone 212 and the third blank zone 216. That is, the first red light buffer zone 217a, the red light conversion zone 212 and the second red light buffer zone 217b are adjacent to each other in sequence. The structure and material of the first red light buffer zone 217a and the second red light buffer zone 217b can be the same as those of the red light conversion zone 212. For example, while making the red light conversion zone 212, the first red light buffer zone 217a and the second red light buffer zone 217b located on both sides of the red light conversion zone 212 can be formed.

[0078] The first green light buffer zone 218a is disposed between the green light conversion zone 213 and the first blank zone 214, and the second green light buffer zone 218b is disposed between the green light conversion zone 213 and the second blank zone 215, that is, the first green light buffer zone 218a, the green light conversion zone 213 and the second green light buffer zone 218b are adjacent to each other in sequence; the structure and material of the first green light buffer zone 218a and the second green light buffer zone 218b can be the same as those of the green light conversion zone 213. For example, while making the green light conversion zone 213, the first green light buffer zone 218a and the second green light buffer zone 218b located on both sides of the green light conversion zone 213 can be formed.

[0079] The first blue light buffer 219a is disposed between the scattering region 211 and the second blank region 215, and the second blue light buffer 219b is disposed between the scattering region 211 and the third blank region 216. That is, the first blue light buffer 219a, the scattering region 211 and the second blue light buffer 219b are adjacent to each other in sequence. The structure and material of the first blue light buffer 219a and the second blue light buffer 219b can be the same as those of the scattering region 211. For example, while making the scattering region 211, the first blue light buffer 219a and the second blue light buffer 219b located on both sides of the scattering region 211 can be formed.

[0080] By setting a small section at the front and rear edges of the blank area to match the adjacent area, it is possible to prevent incomplete light spots from appearing at the boundary positions (such as...). Figure 5 The elliptical light spot A is used to avoid abnormal brightness. The size of the light spot A determines the angle of the buffer zone. The larger the size of the light spot A, the larger the angle of the buffer zone.

[0081] Optionally, sections that are not filled with fluorescence or have scattering function can be provided on the wavelength conversion device 20 to reduce material consumption and reduce the weight of the wavelength conversion device 20.

[0082] Understandably, the angles of the blank areas and buffer zones can also be integer multiples of a preset angle. That is, the angles of the red light conversion area 212, green light conversion area 213, scattering area 211, first blank area 214 to third blank area 216, first red light buffer zone 217a, second red light buffer zone 217b, first green light buffer zone 218a, second green light buffer zone 218b, first blue light buffer zone 219a, and second blue light buffer zone 219b are integer multiples of a preset angle. This preset angle is an angle value that is set in advance based on experience or application needs, such as 5°.

[0083] Furthermore, setting the angle of each color partition to an integer multiple of the preset angle serves the purpose that the modulation scheme design must consider four synchronizations (PWM, color allocation, wavelength conversion device 20, and liquid crystal response) and the overall display quality (white balance, brightness, or reduction of crosstalk interference, etc.). Therefore, setting the preset angle simplifies the entire design, optimizes the execution efficiency of the driver chip, and directly affects the cost and power consumption of the driver chip. Additionally, when the angle is not divisible, the clock frequency must be designed to be higher to meet the least common multiple of the driving signal frequency of the light source 10 and the driving signal frequency of the liquid crystal modulation component 30. Understandably, since the rotation speed of the wavelength conversion device 20 is fixed (i.e., it rotates at a constant speed without any speed variation), in practical applications, the driving signal frequency can be disregarded; it is sufficient to ensure that the period of the wavelength conversion device 20 corresponds to the period of the light source 10 and the period of the liquid crystal modulation component 30.

[0084] Based on the display system described above, the specific solution for improving the color crosstalk problem adopted in this embodiment is as follows:

[0085] Multiple pixel frame periods include a red pixel frame period, a green pixel frame period, and a blue pixel frame period; the durations of the red, green, and blue pixel frame periods are the same; or the durations of the red, green, and blue pixel frame periods are different, for example: the duration of the green pixel frame period is longer than the duration of the red pixel frame period, and the duration of the red pixel frame period is longer than the duration of the blue pixel frame period. Figure 6 As shown, the red pixel frame cycle includes 4 PWM cycles, the green pixel frame cycle includes 6 PWM cycles, and the blue pixel frame cycle includes 2 PWM cycles. Each PWM cycle corresponds to a 30° region of the wavelength conversion device 20. That is, within the time interval of one PWM cycle, the wavelength conversion device 20 rotates 30°, and within the time interval of one frame cycle, the wavelength conversion device 20 rotates 360°.

[0086] In a specific embodiment, during a pixel frame period, when the gray value of a pixel is less than a preset gray value, the waveform of the first PWM signal in the pixel frame modulation signal corresponding to that pixel starts at a low level and ends at a high level; when the gray value of the pixel is greater than or equal to the preset gray value, the waveform of the first PWM signal in the pixel frame modulation signal corresponding to that pixel starts at a high level and ends at a low level.

[0087] For example, assuming each pixel frame period includes 4 PWM cycles, in an 8-bit system, the preset grayscale value can be set to 128. Taking a pixel as an example, assuming the grayscale value of the pixel is 63 in the image data to be displayed in the Mth (M≥1)th pixel frame, the grayscale value of the pixel is 191 in the image data to be displayed in the (M+1)th pixel frame, and the grayscale value of the pixel is 223 in the image data to be displayed in the (M+2)th frame; according to the switching characteristics of the liquid crystal between any two grayscale levels, the PWM signals corresponding to two consecutive PWM cycles can be combined into a single pulse. When the grayscale value of the pixel switches from 63 to 191, the waveform of the corresponding digital modulation signal is shown in Figure 7(a). The PWM period P1-P4 corresponds to the Mth pixel frame period, and the PWM period P5-P8 corresponds to the M+1th pixel frame period. The PWM period P1-P4 corresponds to the waveform of grayscale value 63, and the PWM period P5-P8 corresponds to the waveform of grayscale value 191. It can be seen that since the grayscale value 63 is less than the grayscale value 128, the PWM signal corresponding to the PWM period P1 starts with a low level and ends with a high level. Since the grayscale value 191 is greater than the grayscale value 128, the PWM signal corresponding to the PWM period P5 starts with a high level and ends with a low level. When the grayscale value of the pixel switches from 191 to 223, the waveform of the corresponding digital modulation signal is shown in Figure 7(b). The PWM period P9-P12 corresponds to the frame period of the (M+2)th pixel, and the waveform of the grayscale value 223 corresponds to the PWM period P9-P12. It can be seen that since the grayscale value 223 is greater than the grayscale value 128, the PWM signal corresponding to the PWM period P9 starts with a high level and ends with a low level.

[0088] In some embodiments of the present invention, the waveforms of the PWM signals corresponding to pixels of the same color within the same pixel frame period may be different; for example, Figure 2 As shown, the waveform of the PWM signal in the third PWM cycle is the same as that in the fourth PWM cycle. The waveform of the PWM signal in the first PWM cycle is different from that in the second and third PWM cycles. The waveform of the PWM signal in the second PWM cycle is different from that in the third PWM cycle.

[0089] Based on the function of different PWM cycles within the same pixel frame period, the signal can be divided into a first PWM cycle group and a second PWM cycle group. The pixel frame modulation signal, in sequence, includes at least a first PWM signal group (corresponding to the first PWM cycle group) for meeting the liquid crystal response requirements and a second PWM signal group (corresponding to the second PWM cycle group) for meeting grayscale requirements. The first PWM signal group includes at least one PWM cycle, such that the time corresponding to the first PWM signal group is greater than the liquid crystal response time, and the difference between the time corresponding to the first PWM signal group and the liquid crystal response time is less than the time of one PWM cycle. That is, the PWM cycles included in the first PWM cycle group exactly cover the LC response time.

[0090] In some embodiments of the present invention, within a pixel frame period, there exists at least a first grayscale range, such that when the grayscale value of a pixel is within the first grayscale range, the waveforms of the PWM signals of the first PWM signal group and the second PWM signal group corresponding to that pixel are different. It is understood that, typically, to meet liquid crystal response requirements, in some embodiments of the present invention, the PWM signals of the first PWM signal group and the second PWM signal group are not the same at any grayscale value. This technical solution can maximize the optimization of display effects, making the displayed image grayscale more accurate.

[0091] Understandably, the waveforms of each PWM cycle within the second PWM signal group can also be different; or, for ease of adjustment, the waveforms of each PWM cycle within the second PWM signal group can be set to be the same.

[0092] Optionally, to save computational resources (including hardware costs and software power consumption), the waveforms of the PWM signals corresponding to pixels of the same color within the same frame period can also be identical. Different computational schemes are chosen based on different performance or cost considerations.

[0093] In the application scenario of liquid crystal spatial light modulator, this embodiment is based on digital modulation mode and adopts a liquid crystal modulation method based on a backward lookup table method. The waveform of the PWM signal of the current pixel frame is determined according to the gray level of the previous pixel frame and the gray level of the current pixel frame. By combining the binary rudder with PWM two-dimensional control, the waveform of the PWM signal can be quickly determined, which enables the liquid crystal to accelerate the change of direction, thereby shortening the switching time required for the liquid crystal to switch from the previous gray value to the current gray value. This prevents problems such as color crosstalk caused by slow liquid crystal response speed and helps to improve display quality.

[0094] Please see Figure 8 , Figure 8 This is a flowchart illustrating an embodiment of the display method provided in this application. The method is applied to the display system in the above embodiment and includes:

[0095] Step 81: Control the image processor to determine the waveform of the digital modulation signal based on the image data of the previous pixel frame and the image data of the current pixel frame.

[0096] Specifically, the waveform of the pixel frame modulation signal for the current pixel frame period is determined based on the image data of the previous pixel frame period and the image data of the current pixel frame period.

[0097] A controllable light source generates a second light source, which can be a pure laser light source or an LED light source; that is, the second light source can be laser and / or LED light. Then, a wavelength conversion device is controlled to process the second light source to obtain the first light source. Specifically, the wavelength conversion device includes multiple color zones. When the second light source is incident on a color zone, the color zone can scatter the second light source and transmit / reflect it to the liquid crystal modulation component, or convert the second light source into light of other colors / wavelengths.

[0098] The image processor receives video data, processes it, and obtains multiple frames of image data. The frame period of the digital modulation signal includes multiple pixel frame periods, and each pixel frame period is divided into multiple PWM periods, meaning each pixel frame period includes multiple PWM periods. The pixel frame modulation signal corresponds to the pixel frame period, and the PWM signal corresponds one-to-one with the PWM period.

[0099] Step 82: Control the liquid crystal modulation component to modulate the first light source light based on the digital modulation signal to obtain the image light.

[0100] The liquid crystal modulation component can be an LCoS. After receiving the first light source light and the digital modulation signal, the LCoS can use the digital modulation signal to modulate the first light source light to generate the corresponding image light.

[0101] To reduce the impact of slow liquid crystal response on display, this embodiment uses the grayscale value of the current pixel frame image and the grayscale value of the previous pixel frame image to directly determine the waveform of the current digital modulation signal. By controlling the waveform of the digital modulation signal, the response speed of the liquid crystal is accelerated. There is no need to improve the display effect by changing the driving voltage or the grayscale value of the pixels, which is simple to implement.

[0102] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A display system, characterized in that, include: A liquid crystal modulation component is used to modulate the light from a first light source based on a digital modulation signal to obtain image light. The frame period of the digital modulation signal in each frame includes multiple pixel frame periods, and the pixel frame period includes multiple PWM periods. The digital modulation signal in each frame includes multiple pixel frame modulation signals corresponding to the pixel frame period. Each pixel frame modulation signal includes multiple PWM signals, and the PWM signals correspond one-to-one with the PWM periods. An image processor is configured to determine the waveform of the pixel frame modulation signal in the current pixel frame period based on image data from the previous pixel frame period and image data from the current pixel frame period, which are two consecutive pixel frame periods. In one pixel frame period, when the gray value of a pixel is less than a preset gray value, the waveform of the first PWM signal in the pixel frame modulation signal corresponding to that pixel starts with a low level and ends with a high level; when the gray value of the pixel is greater than or equal to the preset gray value, the waveform of the first PWM signal in the pixel frame modulation signal corresponding to that pixel starts with a high level and ends with a low level.

2. The display system according to claim 1, characterized in that, The duration of each PWM cycle is equal, and the waveform of the PWM signal corresponding to a single pixel contains at most one high level and one low level.

3. The display system according to any one of claims 1-2, characterized in that, The pixel frame modulation signal includes, in a timing sequence, at least a first PWM signal group for meeting the liquid crystal response requirements and a second PWM signal group for meeting the grayscale requirements. The first PWM signal group includes at least one PWM cycle. The time corresponding to the first PWM signal group is greater than the liquid crystal response time, and the difference between the time corresponding to the first PWM signal group and the liquid crystal response time is less than the time of one PWM cycle. Within a pixel frame period, there exists at least a first grayscale range such that when the grayscale value of a pixel is within the first grayscale range, the waveforms of the PWM signals of the first PWM signal group and the PWM signals of the second PWM signal group corresponding to that pixel are different.

4. The display system according to claim 1, characterized in that, The plurality of pixel frame cycles include a red pixel frame cycle, a green pixel frame cycle, and a blue pixel frame cycle. The duration of the green pixel frame cycle is longer than that of the red pixel frame cycle, and the duration of the red pixel frame cycle is longer than that of the blue pixel frame cycle. The red pixel frame cycle, the green pixel frame cycle, and the blue pixel frame cycle together comprise 6 to 15 PWM cycles.

5. The display system according to claim 1, characterized in that, Also includes: A light source, used to generate light from a second light source; A wavelength conversion device is disposed in the optical path of the second light source to process the second light source to obtain the first light source. The wavelength conversion device includes multiple color zones, which include a red light conversion zone, a green light conversion zone, and a scattering zone arranged along a ring direction, for sequentially generating red fluorescence, green fluorescence, and blue light.

6. The display system according to claim 5, characterized in that, The angle of the color partition is an integer multiple of a preset angle, and the duration of the PWM cycle is an integer multiple of the duration corresponding to the preset angle.

7. The display system according to claim 5, characterized in that, The plurality of color zones further include a first blank area, a second blank area, and a third blank area, wherein the light source is in an off state in the first blank area, the second blank area, and the third blank area; the first blank area is located between the red light conversion area and the green light conversion area, the second blank area is located between the green light conversion area and the scattering area, and the third blank area is located between the scattering area and the red light conversion area; wherein the angles of the first blank area, the second blank area, and the third blank area are related to the liquid crystal response time of the liquid crystal modulation component.

8. The display system according to claim 1, characterized in that, The display system further includes a storage device for storing a lookup table that establishes the relationship between the image data of two consecutive pixel frame periods and the waveform of the pixel frame modulation signal of the current pixel frame period.

9. A display method, characterized in that, The method, applied to the display system of any one of claims 1-8, comprises: The control image processor determines the waveform of the pixel frame modulation signal for the current pixel frame period based on the image data of the previous pixel frame period and the image data of the current pixel frame period. The frame period corresponding to the digital modulation signal includes multiple pixel frame periods, and the pixel frame period includes multiple PWM periods. Each frame of the digital modulation signal includes multiple pixel frame modulation signals corresponding to the pixel frame period, and each pixel frame modulation signal includes multiple PWM signals. The PWM signals correspond one-to-one with the PWM periods. The liquid crystal modulation component is controlled to modulate the first light source light based on the digital modulation signal to obtain image light.

Images