Light source and projection device

Abstract

The embodiment of the present application discloses a light source and a projection device, the light source comprising: a laser light source; a color wheel, the color wheel comprising at least two partitions, different partitions generate different primary color lights after being irradiated by the laser light source or different partitions are used to change the light path direction of the laser light source, the partition proportions are relatively balanced, and are set to a preset proportion, for improving the display frame rate. The light source provided in this embodiment sets the partition proportions of the color wheel to a relatively balanced preset proportion, so that the primary color lights corresponding to different partitions can meet the preset color balance standard after being synthesized, so that the time duty ratio of each primary color light can be more balanced when displaying the white field, thereby achieving the improvement of the display frame rate while maintaining the display effect.

Description

Technical Field

[0001] The present application relates to the field of laser display technology, and more specifically, to a light source and a projection device. Background Art

[0002] In recent years, people have been increasingly demanding projection display effects, and laser light sources have begun to be used more and more widely in display fields (such as projection fields). Laser light sources have the advantages of high energy density and small optical extension. In the field of high-brightness light sources, laser light sources have gradually replaced light bulbs and LED light sources. Among them, light sources that use laser light sources to excite phosphors to produce the required light (such as blue lasers excite red and green phosphors to produce white light) have become the mainstream of application due to their high light efficiency, good stability, and low cost. However, in laser projection display, the display frame rate will gradually decrease as the display continues, which will affect the display effect of the projected image.

[0003] As a way, the display frame rate can be increased by increasing the rotation speed of the color wheel or using a multi-segment color wheel. However, when increasing the display frame rate by these methods, if the color wheel rotation speed is increased, the display time of a single primary color light in each frame will decrease, which may lead to a reduction in color bit depth, thus affecting the display effect of the projected image. If a multi-segment color wheel is used to increase the display frame rate, when the color wheel partitions increase, the partition angle of each primary color light will decrease, which may lead to problems such as increased synchronization accuracy requirements for the color wheel and reduced light efficiency, thereby reducing the display effect of the projected image. Summary of the invention

[0004] In view of the above problems, the present application proposes a light source and a projection device to improve the above problems.

[0005] In a first aspect, an embodiment of the present application provides a light source, comprising: a laser light source; a color wheel, wherein the color wheel comprises at least two partitions, and different partitions produce different primary color lights after being irradiated by the laser light source, and the proportions of the partitions are relatively balanced and set to a preset ratio, so as to improve the display frame rate.

[0006] In a second aspect, an embodiment of the present application provides a projection device, which adopts the light source described in the first aspect.

[0007] The present application provides a light source and a projection device, the light source comprising: a laser light source; a color wheel, the color wheel comprising at least two partitions, different partitions generate different primary color lights after being irradiated by the laser light source or different partitions are used to change the light path direction of the laser light source, the partition proportions are relatively balanced, and are set to a preset proportion, for improving the display frame rate. The light source provided in this embodiment sets the partition proportions of the color wheel to a relatively balanced preset proportion, so that the primary color lights corresponding to different partitions can meet the preset color balance standard after being synthesized, and the time duty ratio of each primary color light can be more balanced when displaying the white field, thereby achieving the improvement of the display frame rate while maintaining the display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0009] Figure 1 A comparison diagram of the effects of grayscale images corresponding to different bit depths in the prior art is shown.

[0010] Figure 2 An example diagram of the application environment of the light source proposed in the embodiment of the present application is shown.

[0011] Figure 3 An example diagram of the distribution of blue laser current and color wheel timing in the prior art is shown.

[0012] Figure 4 An example diagram of the distribution of blue laser current and color wheel timing in this application is shown.

[0013] Figure 5 A front view of the red, green and blue color wheel proposed in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0015] In recent years, as projection technology has been widely used in various applications such as movie playback, conferences, and publicity, people's requirements for the effects of projection display have continued to increase. Laser light sources have begun to be used more and more widely in the display field (such as the projection field). Due to the advantages of high energy density and small optical extension, laser light sources have gradually replaced light bulbs and LED light sources in the field of high-brightness light sources. Among them, light sources that use laser light sources to excite phosphors to produce the required light (such as blue lasers excite red and green phosphors to produce white light) have become the mainstream of application due to their high light efficiency, good stability, and low cost. However, in laser projection display, the display frame rate will gradually decrease as the display continues, which will affect the display effect of the projection picture.

[0016] As a way, the display frame rate can be increased by increasing the rotation speed of the color wheel or using a multi-segment color wheel. However, when increasing the display frame rate by these methods, if the color wheel rotation speed is increased, the display time of a single primary color light in each frame will decrease, which may lead to a reduction in color bit depth, thus affecting the display effect of the projected image. If a multi-segment color wheel is used to increase the display frame rate, when the color wheel partitions increase, the partition angle of each primary color light will decrease, which may lead to problems such as increased synchronization accuracy requirements for the color wheel and reduced light efficiency, thereby reducing the display effect of the projected image.

[0017] Therefore, in order to improve the above-mentioned problem, the inventor proposed a light source provided in the present application, which can set the partition ratio of the color wheel to a relatively balanced preset ratio, so that the primary color lights corresponding to different partitions can meet the preset color balance standard after synthesis, and the time duty ratio of each primary color light can be more balanced when displaying the white field, thereby achieving an increase in the display frame rate while maintaining the display effect.

[0018] In order to better understand the present application, the following is a brief description of the relevant technologies involved in the implementation of the present application:

[0019] Bit depth, also known as color depth, refers to the number of bits required to represent the grayscale information of a pixel in a grayscale image. The greater the bit depth, that is, the more bits are required, the smaller the difference between adjacent grayscale values, the less obvious the numerical sampling of analog information, and the more natural and smooth the transition of grayscale differences in the image. See Figure 1 , shows the effect comparison of grayscale images corresponding to different bit depths, such as Figure 1 As shown, a grayscale image with a bit depth of 1 has only 2 1 = 2 states, namely bright and dark; while the image pixels with a display bit depth of 8 can have 2 8 = 256 grayscale states, that is Among them I mis the maximum brightness that can be displayed. Optionally, another concept related to bit depth is called the least significant bit (LSB), which corresponds to the grayscale difference between two adjacent grayscales in the display. For a grayscale display with a bit depth of n, the brightness corresponding to LSB is I m / 2 n .

[0020] DMD (Digital Micromirror Device) adjusts the grayscale of a single pixel by adjusting the time duty cycle of the on state of a single micromirror. Assuming that DMD can achieve 15-bit RGB display within one frame (1 / 60 = 16.67ms), and the timing of the three RGB colors is evenly distributed, that is, one color subframe can achieve 5-bit grayscale display. Each color lighting time is flipped 2 5 = 32 times, the time required to complete each flip is The time corresponding to the LSB (least significant bit) flip. As a way, the time corresponding to the LSB+1 bit can be doubled, and the time corresponding to the higher bits can be doubled successively. It is worth noting that each flip of the DMD micromirror can be controlled independently, that is, each flip of the DMD bit plane is independent, which is important for matching the high refresh rate of the lighting later to achieve the reduction of color breakup.

[0021] In the existing DLP (digital light processing) display system, uniform and stable light is illuminated to the DMD (digital micromirror device). The grayscale value of the corresponding pixel is controlled by controlling the proportion of time that a single reflective lens is in the "on" state in the previous frame of the DMD. The minimum grayscale value that can be achieved depends on the operation time corresponding to the LSB. The time required for a single lens to flip from one state to another is called the crossover time, which is about a few microseconds, and varies slightly with different processes and structures. The time that can be switched between two consecutive states is called the switching time, which is about 20 microseconds. Therefore, the proportion of a single switching time in the time required to display a frame of grayscale image determines the brightness of the LSB.

[0022] Optionally, for a single DMD RGB three-color projection display system, if the frame rate is 60 Hz, the average time corresponding to each color is Can achieve about 2 8-1 = 255 switching times, so for a single DMD projection display system, the bit depth corresponding to each RGB color is generally 8 bits.

[0023] The blue laser used in the light source of the projector generally has a lifespan of about 20,000 hours. Under normal operating conditions, the aging of the laser is generally gradual degradation, that is, during the working process, the non-luminescent centers of the material gradually increase after a large number of electron-hole combinations, and the cavity surface of the resonant cavity gradually ages. Another common mechanism of laser damage is catastrophic optical damage (COD), the principle of which is that the light-generating material in the laser absorbs more light under high light power density and generates heat. The heat generated causes the material to melt or recrystallize, which further enhances the light absorption, thus forming a positive feedback process, which eventually causes the mirror of the laser resonant cavity to fail and cause laser damage. Unlike gradual aging, COD is much faster, manifested as a sudden decrease in brightness. The laser flux threshold for COD is related to the pulse length of the laser (Chin AK, et al, (2013) Catastrophic optical damage in high-power, broad-area laser diodes. In: Ueda O., Pearton S. (eds) Materials and reliability handbook for semiconductor optical and electron devices. Springer, New York, NY). In the pulsed working mode, the time duty cycle of the on state is less than 1, and the average heat generation power is lower than the heat generation power of the same optical power in the CW mode, so it can withstand stronger optical power. In other words, in the pulsed working mode, the brightness of the illumination of the laser light source can be improved compared with the CW working mode.

[0024] In laser projectors, the pulse duration of the current is generally in the order of milliseconds (ms), (longer than the general microsecond or even nanosecond order, here referred to as a long pulse), so if the drive current is increased by only a few times (about 5 times), the COD phenomenon is not obvious, that is, the optical power output under the reference current set by the laser does not reach the order of magnitude that produces the COD phenomenon, resulting in more laser damage during the gradual aging process. In this case, the inventors of the present application have discovered that the brightness of the laser can be increased in a short time by means of an overdrive pulse current. It should be noted that overdrive here refers to the use of a drive current that exceeds the absolute maximum ratings of operating current of the laser.

[0025] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0026] See also Figure 2 , is an example diagram of the application environment of the light source proposed in the embodiment of the present application. Figure 2 As shown, the light source provided in this embodiment may include a laser light source 202, a color wheel 301, and a power control module 203. The laser light source 202 may be a blue laser. In some possible implementations, the laser light source 202 may also be a light emitting diode, a laser diode, or other solid-state light source. The color wheel 301 may include at least two partitions. The color wheel 301 is a spectroscopic color wheel. Optionally, different partitions are used to change the direction of the light path of the laser light source after being irradiated by the laser light source 202. In other implementations, the color wheel may also be a fluorescent color wheel. Different partitions may be set to generate different primary color lights.

[0027] For example, as an embodiment, the color wheel may be a yellow-blue spectroscopic color wheel, in which case at least two partitions of the color wheel may include a yellow partition and a blue partition. The yellow partition may transmit blue light after being irradiated by a laser light source, and then excite the fluorescent color wheel in the rear optical path to generate yellow light, and the blue partition may generate blue-based light after being irradiated by a laser light source. Different partitions are used to change the direction of the optical path of the laser light source after being irradiated by the laser light source 202. As another embodiment, the color wheel may be a red-green-blue color wheel, in which case at least two partitions of the color wheel may include a red partition, a green partition, and a blue partition. The red partition may generate red-based light after being irradiated by a laser, the green partition may generate green-based light after being irradiated by a laser, and the blue partition may generate blue-based light after being irradiated by a laser. In practical applications, the above functions may be achieved by arranging different wavelength conversion materials on at least two color segments of the color wheel.

[0028] It should be noted that, in the embodiment of the present application, at least two partitions of the color wheel can be divided into two types of partitions, and the two types of partitions can be a first partition and a second partition. Among them, the first partition is a partition whose corresponding angle (the angle corresponding to the first partition can be understood as the total angle of the same partition on the color wheel) is increased compared to the first target angle (which can be understood as the total angle of the same partition on the color wheel in the prior art). Optionally, if the current partition corresponding to the laser light source is the first partition, relative to the luminous flux of the laser light source corresponding to the partition corresponding to the color wheel in the prior art, in order to achieve white balance, specifically, the power control module can modulate the current of the laser light source in real time according to the control signal sent by the control module of the entire projection device, thereby changing the luminous flux of the laser light source in the corresponding section, that is, reducing the luminous flux of the laser light source. Optionally, the second partition is a partition whose corresponding angle (the angle corresponding to the second partition can be understood as the total angle of the same partition on the color wheel in the prior art) is reduced compared to the second target angle (which can be understood as the total angle of the same partition on the color wheel in the prior art). Optionally, if the current partition corresponding to the laser light source is the second partition, relative to the luminous flux of the laser light source corresponding to the partition corresponding to the color wheel in the prior art, in order to achieve white balance, the luminous flux of the laser light source can be increased. Similarly, the power control module can modulate the current of the laser light source in real time according to the control signal sent by the control module of the entire projection device, thereby changing the luminous flux of the laser light source in the corresponding section, that is, increasing the luminous flux of the laser light source, and setting the angles of the first partition and the second partition on the color wheel, so that the proportions of different partitions on the color wheel can be more balanced compared to the original color wheel proportions in the prior art.

[0029] Among them, the power control module can be specifically used to obtain the ratio of luminous flux corresponding to each partition irradiated by the laser light source, and then obtain the pulse modulation parameters corresponding to the partition currently irradiated by the laser light source based on the luminous flux ratio. Optionally, in this embodiment, there is no limitation on the method for obtaining the pulse modulation parameters corresponding to the partition currently irradiated by the laser light source based on the luminous flux ratio. Among them, if the color wheel is a yellow-blue spectroscopic color wheel, the luminous flux ratio can be the ratio between the luminous flux irradiated by the laser light source on the blue partition and the luminous flux irradiated by the laser light source on the yellow partition. If the color wheel is a red, green and blue wheel (which can also be understood as an RGB color wheel), the luminous flux ratio can be the ratio between the luminous flux irradiated by the laser light source on the red partition, the luminous flux irradiated by the laser light source on the green partition, and the luminous flux irradiated by the laser light source on the blue partition.

[0030] Optionally, the light source proposed in the embodiment of the present application can be applied to a single-chip or dual-chip DLP (Digital Light Processing) projection display system, which can include projection equipment such as cinema machines, educational machines, laser TVs, and engineering machines. Among them, a color wheel is usually used in a dual-chip DLP projection display system to complete the time domain separation of colors. The principle of dividing different color areas in the color wheel can be that if the spatial light modulator is kept in a fully open state, the light emitted from the lens can be mixed into white within the time it takes for the color wheel to rotate one circle.

[0031] Optionally, in a single-chip DLP projection display system, assuming that the luminous flux of RGB (Y) monochromatic light is 100% in each time duty cycle, it is Φ R , Φ G , Φ B (,Φ Y ), using the additive color mixing principle, we can get the lumen ratios of RGB (Y) primary colors mixed into a specified white light: R , G , B (,ρ Y ). Then the total angle θ of each primary color light on the color wheel is R ,θ G ,θ B (,θ Y ) can be calculated using the following formula:

[0032]

[0033] Optionally, in a dual-chip DLP projection display system, a spectroscopic color wheel can be used to achieve time-domain separation of blue light and yellow light, or a fluorescent color wheel can be used to directly emit blue light and yellow light, and then the red and green spectroscopic film will separate the red light and green light to two spatial light modulators for processing. Assuming that the luminous flux of RGB monochromatic light is 100% when the time duty cycle is Φ R , Φ G , Φ B Using the additive color mixing principle, we can calculate that the lumen ratios when using RGB primary colors to mix a specified white light are ρ R , G , B The total angle θ of each primary color light on the BY color wheel (which can also be understood as the yellow-blue spectroscopic color wheel described later) is B ,θ Y It can be calculated using the following formula (where t R ,t G ,t B They are the durations of displaying RGB color light when synthesizing white light):

[0034] If the B primary color light and the R primary color light are controlled by the same spatial light modulator, the calculation formula can be:

[0035]

[0036] If the B primary color light and the G primary color light are controlled by the same spatial light modulator, the calculation formula can be:

[0037]

[0038] As a way, Figure 2 As shown, if the projection display system is a dual-chip DLP projection display system, the blue laser 202 can be separated into transmitted light and reflected light by the color wheel 301 in a timely manner. The reflected light can excite yellow fluorescence when irradiated on the fluorescent color wheel 402. The yellow fluorescence is collected by the light collecting device 302 and then incident on the prism 305. The yellow fluorescence can be separated into red primary light and green primary light by the red-transmitting and green-reflecting film on the prism 305; the transmitted light is directly combined into the optical path as blue primary light, wherein the red primary light and the green primary light are regulated by the same spatial light modulator 306, and the green primary light is regulated by the spatial light modulator 307.

[0039] As an implementation method, a blue laser with a wavelength of 455nm can be used as the blue primary light, and the fluorescence excited by it is used as the red and green primary light. Optionally, if the fluorescence generated by exciting a typical yellow powder is separated at 590nm to obtain a short-wave band portion as the green primary light and a long-wave band portion as the red primary light, the color coordinates of the RGB primary light can be obtained as R: (0.649, 0.350), G: (0.325, 0.630), B: (0.151, 0.023). Optionally, when the RGB primary light with color coordinates of R: (0.649, 0.350), G: (0.325, 0.630), B: (0.151, 0.023) is combined to produce a recommended white field with coordinates of (0.313, 0.329), the brightness proportions of the RGB primary light can be obtained as R: 19.6%, G: 77.5%, B: 2.9%. Since both green-primary light and red-primary light are generated by blue laser-induced fluorescence, there is a proportional relationship between the luminous flux of the blue laser and the red and green fluorescence it stimulates. Optionally, it is assumed that a blue laser with a luminous flux of 1 lm can stimulate 0.78 lm of red fluorescence and 3.82 lm of green fluorescence.

[0040] In this mode, see Figure 3 , shows an example diagram of the distribution of blue laser current and color wheel timing in the prior art, optionally, as Figure 3As shown, if the laser light source maintains a constant excitation current (I) within time t, the total angles of the blue-transmitting area 3011 and the anti-blue area 3012 on the color wheel (which can be understood as the aforementioned yellow-blue spectroscopic color wheel) 301 are respectively 37° for transmission (B) and 323° for anti-reflection (Y). The blue-transmitting area 3011 refers to the blue partition, and the anti-blue area 3012 refers to the yellow partition. The blue laser reflected by the anti-blue area can be used to excite the yellow phosphor on the fluorescent color wheel to emit yellow light. The blue-transmitting area directly transmits the blue laser. The anti-blue area and the blue-transmitting area reflect the blue laser and transmit the blue laser, and are further used to change the direction of the light path of the blue laser. In this way, when the yellow-blue spectroscopic color wheel is divided into N segments for transmission and reflection (N is a positive integer), if the display bit depth is 8 bits and the shortest opening time of the dual spatial light modulator is 16us, the total display time of the single primary color light in each frame of the picture needs to be greater than (2 8 -1)×16us=4.08ms, if the blue primary color light with the lowest time duty cycle needs to achieve 8-bit grayscale, then the yellow-blue color wheel period (such as Figure 3 T) can be at least In this way, the corresponding equivalent frame rate can be expressed as:

[0041]

[0042] It can be seen that while maintaining the display bit depth, the corresponding display frame rate is low.

[0043] As a way to increase the display frame rate, the proportion of each partition of the color wheel can be changed and relatively balanced. In order to ensure white balance, the luminous flux of the corresponding laser light source of the corresponding partition is changed. The luminous flux is related to the optical power, and the optical power is related to the current, so the current of the corresponding partition of the corresponding laser light source can be adjusted.

[0044] For example, see Figure 4 , shows an example diagram of the distribution of blue laser current and color wheel timing in this application. Figure 4 As shown, as an implementation method, when the color wheel 301 (which can be understood as the aforementioned yellow-blue spectroscopic color wheel) turns to the blue partition 3011, the luminous flux of the blue laser can be configured to Φ1, and when the yellow-blue spectroscopic color wheel turns to the yellow partition 3012, the luminous flux of the blue laser can be configured to Φ2.

[0045] In one embodiment, the ratio of Φ1 and Φ2 can be configured as: Φ1:Φ2=1:8.67. In this way, the total angles of the blue-transmitting area and the anti-blue area on the color wheel 301 are respectively 180° for transmission (B) and 180° for anti-(Y). In this way, the segment ratio of the blue partition to the yellow partition of the yellow-blue spectroscopic color wheel can be 1:1. The yellow partition refers to the anti-blue area, and the blue partition refers to the blue-transmitting area. The blue laser reflected by the anti-blue area can be used to excite the yellow phosphor on the fluorescent color wheel to emit yellow light. The blue-transmitting area directly transmits blue light. The anti-blue area and the blue-transmitting area reflect the blue laser and transmit the blue laser, and are further used to change the direction of the optical path of the blue laser. Optionally, the time average power can be made below the limit power of the power control module.

[0046] In this case, when the yellow-blue color wheel is divided into N segments (N is a positive integer), if the display bit depth is 8 bits and the shortest opening time of the dual-chip spatial light modulator is 16us, the total display time of the single primary color light in each frame of the picture needs to be greater than (2 8 -1)×16us=4.08ms. If the blue primary color light with the lowest time duty cycle needs to achieve 8-bit grayscale, the period T of the yellow-blue color wheel is at least In this way, the corresponding frame rate can be expressed as:

[0047]

[0048] It can be understood that when the total angle corresponding to the blue partition 3011 is Figure 3 The 3011 changes shown are Figure 4 When 3011 is shown, the total angle corresponding to the partition is increased. In this way, the ratio of the luminous flux of the blue laser corresponding to the blue partition by the yellow-blue spectroscopic color wheel irradiated by the laser light source to the luminous flux of the blue laser corresponding to the yellow partition irradiated by the laser light source is 1:8.67. In this embodiment, the total angle of transmission (B) 180° corresponding to the blue partition is larger than the aforementioned transmission (B) 37°, and the total angle of reverse (Y) 180° corresponding to the yellow partition is smaller than the aforementioned reverse (Y) 323°. The resulting display frame rate is 122.5H Z >25H Z, that is, the display frame rate is improved. In other implementations, for a dual-chip DLP projection display system, a yellow-blue beam splitting color wheel may not be provided, and a fluorescent color wheel may be directly used to provide a yellow partition and a blue partition, and a yellow fluorescent powder is provided in the yellow partition, and the blue partition transmits or reflects blue light. The ratio of the luminous flux of the blue laser corresponding to the blue partition irradiated by the laser light source to the luminous flux of the blue laser corresponding to the yellow partition irradiated by the laser light source is still 1:8.67, and then the angles of the blue partition and the yellow partition are 180° and 180°. According to the aforementioned calculated frame rate results and the described principles, the corresponding frame rate is also improved. This implementation method also improves the display frame rate. In another embodiment, the ratio of Φ1 and Φ2 can also be configured as: Φ1:Φ2=1:4. In this case, the total angles of the blue-transmitting area and the blue-reflecting area on the yellow-blue spectroscopic color wheel can be 114° for transmission (B) and 246° for reflection (Y), respectively. In this way, the ratio of the blue partition to the yellow partition of the yellow-blue spectroscopic color wheel can be 0.46:1. When the yellow-blue spectroscopic color wheel is divided into N segments for transmission and reflection, if the display bit depth is 8 bits and the shortest opening time of the spatial light modulator is 16us, the total display time of the single primary color light in each frame of the picture needs to be greater than (2 8 -1)×16us=4.08ms. If the blue primary color light with the lowest time duty cycle needs to achieve 8-bit grayscale, the period T of the yellow-blue color wheel can be at least: In this way, the corresponding frame rate can be expressed as:

[0049]

[0050] In order to ensure white balance, the ratio of the luminous flux of the blue laser corresponding to the blue partition irradiated by the laser light source and the luminous flux of the blue laser corresponding to the yellow partition irradiated by the laser light source is 1:4, and the luminous flux of the excitation current of the laser light source corresponding to the partition with a larger total angle of the segment is reduced, and the luminous flux of the excitation current of the laser light source corresponding to the partition with a smaller total angle of the segment is increased. In this embodiment, the total angle of transmission (B) 114° corresponding to the blue partition is larger than the aforementioned transmission (B) 37°, and the total angle of anti-reflection (Y) 246° corresponding to the yellow partition is smaller than the aforementioned anti-reflection (Y) 323°, and the resulting display frame rate is 77.6H Z >25H Z, which can improve the display frame rate. In other implementations, for a dual-chip DLP projection display system, a yellow-blue beam splitting color wheel may not be provided, and a fluorescent color wheel may be directly used to provide a yellow partition and a blue partition, wherein a yellow fluorescent powder is provided in the yellow partition, and the blue partition transmits or reflects blue light. The ratio of the luminous flux of the blue laser corresponding to the blue partition irradiated by the laser light source to the luminous flux of the blue laser corresponding to the yellow partition irradiated by the laser light source is still 1:4, and then the angles of the blue partition and the yellow partition are 114° and 246°. According to the aforementioned calculated frame rate results and the described principles, the corresponding frame rate is also improved, and this implementation also improves the display frame rate.

[0051] As another implementation method, when the yellow-blue color wheel is divided into N segments of transmissive and reflective (N is a positive integer), if the display bit depth is increased from 8 bits to 10 bits, and the shortest opening time of the spatial light modulator is 16us, the total display time of the single primary color light in each frame of the picture needs to be greater than (2 10 -1)×16us=16.39ms. If the blue primary color light with the lowest time duty cycle needs to achieve 10-bit grayscale, the period T of the yellow-blue color wheel can be at least: In this way, the corresponding frame rate can be expressed as:

[0052]

[0053] It can be seen that the ratio of the light flux of the blue laser corresponding to the blue partition of the yellow-blue split color wheel irradiated by the laser light source to the light flux of the blue laser corresponding to the yellow partition of the yellow-blue split color wheel irradiated by the laser light source is 1:8.67. On this basis, the number of bits of the display bit depth is increased, and the display frame rate is 30.5H. Z >25H Z , by changing the proportion of each partition of the color wheel and making it relatively balanced to improve the display frame rate, and in order to ensure white balance, the luminous flux of the corresponding laser light source of the corresponding partition is changed. The luminous flux is related to the optical power, and the optical power is related to the current, thereby adjusting the current of the corresponding partition of the corresponding laser light source.

[0054] As another method, if the projection display system is a single-chip DLP projection display system, a blue laser with a wavelength of 455nm can be used as the blue primary color light, and the fluorescence excited by it can be the red and green primary color light. If the fluorescence generated by exciting a typical green powder is separated at 590nm to obtain a short-wave band portion as the green primary color light, the green powder is a phosphor that emits a green light band in the fluorescence spectrum, or it can be a "yellow powder" that includes the green light band, and a typical red powder is excited to obtain a long-wave band portion with a wavelength greater than 590nm as the red primary color light, the red powder is a phosphor that emits a red light band in the fluorescence spectrum, or it can be a "yellow powder" that includes the red light band, then the color coordinates of the RGB primary color light can be obtained as R: (0.649, 0.350), G: (0.325, 0.630), B: (0.151, 0.023). Optionally, when the coordinates (0.313, 0.329) generated by combining the RGB primary colors with color coordinates of R: (0.649, 0.350), G: (0.325, 0.630), and B: (0.151, 0.023) are recommended for the white field, the brightness proportions of the three primary colors are R: 19.6%, G: 77.5%, and B: 2.9%, respectively.

[0055] Since both green-primary light and red-primary light are generated by blue laser-induced fluorescence, there is a proportional relationship between the luminous flux of the blue laser and the red and green fluorescence it stimulates. Optionally, assuming that a blue laser with a luminous flux of 1 lm can stimulate 0.78 lm of red fluorescence or 6.06 lm of green fluorescence, in this way, the total angles corresponding to RGB on the red, green and blue wheel can be obtained as R: 222°, G: 113°, and B: 25°, respectively. When the red, green and blue wheel is divided into N segments of RGB (N is a positive integer), if the display bit depth is 8 bits and the shortest on-time of the spatial light modulator is 16 us, the total display time of the single-primary color light in each frame of the picture needs to be greater than (2 8 -1)×16us=4.08ms, if the blue primary color light with the lowest time duty cycle needs to achieve 8-bit grayscale, the period of the red, green and blue wheel can be at least In this way, the corresponding frame rate can be expressed as:

[0056]

[0057] As a way to increase the display frame rate, the proportion of each partition of the color wheel can be changed and relatively balanced. In order to ensure white balance, the luminous flux of the corresponding laser light source of the corresponding partition is changed. The luminous flux is related to the optical power, and the optical power is related to the current, so the current of the corresponding partition of the corresponding laser light source can be adjusted.

[0058] As an implementation, see Figure 5 , shows the front view of the red, green and blue color wheel provided in this embodiment. Figure 5As shown, the color wheel 301 is a red, green and blue wheel, which is a fluorescent color wheel, including a red partition 3013, a green partition 3014 and a blue partition 3015 (the specific locations of the partitions may not be limited). Optionally, when the red, green and blue colors rotate to the red partition 3013, the light flux of the blue laser may be configured to be Φ1, when the red, green and blue colors rotate to the green partition 3014, the light flux of the blue laser may be configured to be Φ2, and when the red, green and blue colors rotate to the blue partition 3015, the light flux of the blue laser may be configured to be Φ3. Other structural parts of the projection display system are set as required.

[0059] In one embodiment, the ratio of Φ1, Φ2 and Φ3 can be configured as: Φ1:Φ2:Φ3=8.67:4.41:1. In this way, the corresponding total angles on the RGB color wheel can be R: 120°, G: 120°, B: 120°, respectively. In this way, if the color wheel in this embodiment is a red, green and blue wheel (RGB color wheel), the red partition, green partition and blue partition of the color wheel can be 1:1:1. When the RGB color wheel is divided into N segments of RGB (N is a positive integer), if the display bit depth is 8 bits and the shortest opening time of the spatial light modulator is 16us, the total display time of the single primary color light in each frame of the picture needs to be greater than (2 8 -1)×16us=4.08ms. If the blue primary color light with the lowest time duty cycle needs to achieve 8-bit grayscale, the period of the RGB color wheel is at least In this way, the frame rate corresponding to the light source can be expressed as:

[0060]

[0061] It can be seen that in order to ensure white balance, the ratio of the light flux of the blue laser corresponding to the red partition irradiated by the laser light source, the light flux of the blue laser corresponding to the green partition irradiated by the laser light source, and the light flux of the blue laser corresponding to the blue partition irradiated by the laser light source is adjusted to Φ1:Φ2:Φ3=8.67:4.41:1, wherein the total angle 120° corresponding to the red partition is smaller than the aforementioned 222°, the total angle 120° corresponding to the green partition is larger than the aforementioned 113°, and the total angle 120° corresponding to the blue partition is larger than the aforementioned 25°, and the display frame rate is 81.7H. Z >17H Z , improving the display frame rate.

[0062] In another embodiment, in order to reduce the illumination light modulation frequency, based on the above embodiment, when the RGB color wheel is rotated to the red partition and the green partition, the luminous flux of the blue laser is configured to be Φ1, and when it is rotated to the blue partition, the luminous flux of the blue laser is configured to be Φ3. In this way, the ratio of Φ1 to Φ3 can be configured as: Φ1:Φ3=4.41:1, then, the luminous flux of the blue laser corresponding to the rotation of the red, green and blue colors irradiated by the laser light source to the red partition and the luminous flux of the blue laser corresponding to the rotation of the red, green and blue colors irradiated by the laser light source to the green partition and the luminous flux of the blue laser corresponding to the rotation of the red, green and blue colors irradiated by the laser light source to the blue partition is 4.41:4.41:1. In this case, the corresponding total angles on the RGB color wheel can be R: 178°, G: 91°, B: 91°, respectively. In this way, if the color wheel is a red, green and blue wheel (RGB color wheel), the segment ratio of the red partition, the green partition and the blue partition of the color wheel can be 1.96:1:1. When the color wheel is divided into N segments of RGB (N is a positive integer), if the display bit depth is 8 bits and the shortest opening time of the spatial light modulator is 16us, the total display time of the single primary color light in each frame of the picture needs to be greater than (2 8 -1)×16us=4.08ms, if the blue primary color light with the lowest time duty cycle needs to achieve 8-bit grayscale, the period of the red, green and blue wheel can be at least In this way, the corresponding frame rate can be expressed as:

[0063]

[0064] It can be seen that in order to ensure white balance, the ratio of the blue laser light flux corresponding to the red partition irradiated by the laser light source and the blue laser light flux corresponding to the green partition irradiated by the laser light source and the blue laser light flux corresponding to the blue partition irradiated by the laser light source is adjusted to 4.41:4.41:1. Among them, the total angle 178° corresponding to the red partition is smaller than the aforementioned 222°, the total angle 91° corresponding to the green partition is smaller than the aforementioned 113°, and the total angle 91° corresponding to the blue partition is larger than the aforementioned 25°, and the display frame rate is 62.0H. Z >17H Z , increase the display frame rate.

[0065] The light source provided in the embodiment of the present application can set the partition ratio of the color wheel to a relatively balanced preset ratio, so that the primary color lights corresponding to different partitions can meet the preset color balance standard after synthesis, and the time duty ratio of each primary color light can be more balanced when displaying the white field, thereby achieving an increase in the display frame rate while maintaining the display effect.

[0066] Optionally, this embodiment further provides a projection device, which may include the light source in the above embodiment. The adjustment principle and working process of the light source in the projection device may refer to the description in the above embodiment, which will not be repeated here.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A light source, characterized in that: include: Laser light source; A color wheel, wherein the color wheel includes at least two partitions, and light emitted from different partitions after being irradiated by the laser light source is used to generate different primary color lights or different partitions are used to change the direction of the light path of the laser light source. The different partitions are correspondingly configured with different luminous flux ratios. The at least two partitions include a yellow partition and a blue partition. The luminous flux ratio is the ratio between the luminous flux irradiated by the laser light source on the blue partition and the luminous flux irradiated by the laser light source on the yellow partition, and the ratio is 1:8.

67. The segment ratio of the blue partition to the yellow partition is 1:1, so that the primary color lights corresponding to different partitions can meet the preset color balance standard after synthesis, and the time duty cycle of each primary color light is balanced when displaying the white field, so as to improve the display frame rate.

2. A light source, characterized in that: include: Laser light source; A color wheel, wherein the color wheel includes at least two partitions, and light emitted from different partitions after being irradiated by the laser light source is used to generate different primary color lights or different partitions are used to change the direction of the light path of the laser light source. The different partitions are correspondingly configured with different luminous flux ratios. The at least two partitions include a yellow partition and a blue partition. The luminous flux ratio is the ratio between the luminous flux irradiated by the laser light source on the blue partition and the luminous flux irradiated by the laser light source on the yellow partition. The ratio is 1:4, and the segment ratio of the blue partition to the yellow partition is 0.46:1, so that the primary color lights corresponding to different partitions can meet the preset color balance standard after synthesis, and the time duty cycle of each primary color light is balanced when displaying the white field, so as to improve the display frame rate.

3. The light source according to claim 1 or 2, characterized in that: The laser light source is a blue laser.

4. A projection device, characterized in that: The projection device adopts the light source as described in any one of claims 1-3.

Images