WO2020135298A1 - 投影系统及投影方法 - Google Patents

投影系统及投影方法 Download PDF

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Publication number
WO2020135298A1
WO2020135298A1 PCT/CN2019/127277 CN2019127277W WO2020135298A1 WO 2020135298 A1 WO2020135298 A1 WO 2020135298A1 CN 2019127277 W CN2019127277 W CN 2019127277W WO 2020135298 A1 WO2020135298 A1 WO 2020135298A1
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light
image
frequency
image signal
low
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English (en)
French (fr)
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余新
胡飞
吴超
李屹
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Shenzhen Appotronics Corp Ltd
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Appotronics Corp Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3179—Video signal processing therefor

Definitions

  • the invention relates to the field of projection display, in particular to a projection system and a projection method.
  • some projection systems dynamically change the direction of the laser beam through scanning devices (such as galvanometers, scanning mirrors, etc.) to make them scan on the screen to form a picture.
  • This projection system does not require complicated optical elements, has a simple structure, and has high light utilization efficiency, but it is unable to display high-resolution images due to the limitation of the spot size and the modulation speed of the light source.
  • the collimation and spot size of the beam need to be very small.
  • the beam quality of general multi-mode lasers cannot meet the requirements, and only single-mode lasers can be used, which greatly limits the scanning. Output resolution and brightness of the projection system.
  • the present invention provides a projection system capable of displaying high-brightness, high-resolution images, including an image signal processing module, which is used to input The image signal is decomposed into a low-frequency image signal and a high-frequency image signal; a low-frequency image display module, the low-frequency image display module includes a first light source, a scanning device, and a scanning control unit, and the scanning control unit controls the low-frequency image signal according to the The brightness of the first light source and the position status of the scanning device, so as to scan to form a first image light at a preset position; a high-frequency image display module, the high-frequency image display module includes a second light source and a spatial light modulator, so The spatial light modulator modulates the outgoing light of the second light source according to the high-frequency image signal to form second image light; and a light combining module for combining the first image light and the second image The light is combined and output to the lens.
  • an image signal processing module which is used to input The image signal is decomposed into
  • the light combining module is a polarized light combiner, configured to transmit incident light of a certain polarization state while reflecting incident light of another polarization state.
  • the polarization states of the first image light and the second image light are perpendicular to each other.
  • the deviation angle of the first image light is smaller than the receiving angle of the lens, and the imaging of the first image light on the lens and the second image light on the lens The imaging size is the same.
  • the optical distance between the preset position and the lens and between the spatial light modulator and the lens are equal.
  • the first light source is a laser light source
  • the second light source is any one of a laser light source, a laser fluorescent light source, an LED light source, and a light bulb light source.
  • the present invention also provides a projection method suitable for the above-mentioned projection system, including the following steps: using an image signal processing module to decompose the input image signal into a low-frequency image signal and a high-frequency image signal; and transmitting the low-frequency image signal to the low-frequency image
  • the scanning control unit of the display module controls the brightness of the first light source and the position state of the scanning device, so that the first image light is scanned at a preset position, and at the same time, the high-frequency image signal is sent to the space of the high-frequency image display module
  • the light modulator modulates the outgoing light of the second light source to form a second image light; and a light combining module is used to combine the first image light and the second image light and output it to the lens.
  • using the image signal processing module to decompose the input image signal into a low-frequency image signal and a high-frequency image signal includes the following steps: input image; performing corrosion operation on the RGB channel; and corroding the corrosion according to a preset cut-off frequency f c
  • the low-frequency filtering is performed on the image after that; the signal whose image frequency is less than or equal to f c is obtained according to the negative value of the maximum brightness cutoff and the highlight overflow scanned and displayed in the low-frequency image display module, and the low-frequency image signal is output to The low-frequency image display module; the signal with an image frequency greater than f c is obtained according to the maximum brightness cutoff negative value and the highlight overflow that the spatial light modulator can output to obtain the high-frequency image signal, and the high-frequency image signal is output to all The high-frequency image display module is described.
  • the projection system provided by the invention decomposes the input image into a low-frequency image signal and a high-frequency image signal through an image signal processing module, and adopts a scanning low-frequency image display module to form the first image light according to the low-frequency image signal modulation, and the spatial light modulator is used as a high
  • the high-frequency image display module modulates the second image light according to the high-frequency image signal, and finally superimposes the first image light and the second image light to restore the original image.
  • the present invention combines a scanning projection display and a spatial light modulator-based projection display to relatively reduce the luminous flux incident on the spatial light modulator, thereby increasing the service life of the spatial light modulator.
  • FIG. 1 is a functional block diagram of a projection system provided by the present invention.
  • FIG. 2 is a schematic structural diagram of a projection system according to a preferred embodiment of the present invention.
  • FIG. 3 is a schematic structural diagram of a projection system according to another preferred embodiment of the present invention.
  • FIG. 4 is a flowchart of a projection method provided by the present invention.
  • FIG. 5 is a flowchart of the image signal processing module decomposing the input image in the projection method shown in FIG. 4.
  • FIG. 1 is a schematic block diagram of a projection system 100 provided by the present invention.
  • the projection system 100 includes a low-frequency image display module 110, a high-frequency image display module 120, an image signal processing module 130, a light combining module 140, and a lens 150.
  • the image signal processing module 130 can decompose the input image signal into a low-frequency image signal and a high-frequency image signal according to a preset rule, and send the low-frequency image signal to the low-frequency image display module 110, and the high-frequency image signal to the high-frequency image Display module 120.
  • the first image light obtained by the low-frequency image display module 110 according to the low-frequency image signal and the second image light obtained by the high-frequency image display module 120 according to the high-frequency image signal are combined by the light combining module 140 and enter the lens 150.
  • the low-frequency image display module 110 includes a first light source 111, a scanning device 112, a virtual imaging surface 113, and a scanning control unit 114.
  • the scanning device 112 is disposed in the optical path between the first light source 111 and the virtual imaging surface 113.
  • the first light source 111 and the scanning device 112 are respectively connected to the scanning control unit 114 and controlled by the scanning control unit 114.
  • the working principle of the low-frequency image display module 110 is that the scanning control unit 114 controls the brightness of the first light source 111 and the position state of the scanning device 112 according to the low-frequency image signal, so as to scan to form the first image light at a preset position. Specifically, the outgoing light of the first light source 111 is scanned by the scanning device 112 to form a virtual image on the virtual imaging surface 113, and the scanning control unit 114 estimates the real-time position of the incident spot according to the position state of the scanning device 112 and controls according to the real-time position of the incident spot The brightness of the first light source 111 thus produces a light and dark distribution image on the virtual imaging surface 113.
  • the first light source 111 includes multiple monochromatic light sources, preferably RGB lasers, and the emitted light is polarized light with good collimation.
  • the first light source 111 is not limited to polarized light
  • the low-frequency image display module 110 further includes a first polarizer to change the polarization state of the outgoing light of the first light source 111, so that the first image light has a certain Polarized light in the polarization state.
  • the scanning device 112 is a high-speed scanning device, such as a galvanometer, a scanning mirror, etc., which can rapidly change the direction of incident light periodically, so that the light emitted from the first light source 111 can be quickly scanned at the virtual imaging surface 13.
  • the high-frequency image display module 120 includes a second light source 121, a second polarizer 122, a light collection guide 123, and a spatial light modulator 124.
  • the second polarizer 122 and the light collection guiding device 123 are disposed in the optical path between the second light source 121 and the spatial light modulator 124.
  • the working principle of the high-frequency image display module 120 is that the light emitted from the second light source 121 is converted into polarized light by the second polarizer 122 and guided by the light collection guide device 123 into the spatial light modulator 124 for modulation.
  • the second light source 121 is a uniform illumination light source, and may be any one of a laser fluorescent hybrid light source, a light bulb light source, and an LED light source.
  • the second light source 121 is a laser fluorescent hybrid light source, which includes a laser 1211 and a wavelength conversion device 1212.
  • the laser 1211 can generate excitation light, such as a blue laser
  • the excitation light generated by the laser 1211 enters the wavelength conversion device 1212 can generate fluorescence by exciting phosphors, such as red fluorescence and green fluorescence.
  • the light emitted by the wavelength conversion device 1212 is a mixed light of laser light and fluorescence emitted in time series.
  • the light collecting and guiding device 123 includes a condensing lens 1231 and a relay lens 1232, wherein the condensing lens 1231 is used to collect the outgoing light of the second light source 121, which is necessary when the second light source 121 is a large-angle light source .
  • the relay lens 1232 is used to relay the outgoing light of the second light source 121 into the spatial light modulator 124.
  • the spatial light modulator 124 is specifically an LCOS spatial light modulator
  • the light combining module 140 is specifically a polarizing light combiner, which can transmit incident light of a certain polarization state while reflecting incident light of another polarization state.
  • the second light source 121 and the LCOS spatial light modulator are located on opposite sides of the polarizing beam combiner.
  • the outgoing light of the second light source 121 is converted by the second polarizer 122 into polarized light that can be transmitted by the polarizing beam combiner, and then passes through the LCOS
  • the spatial light modulator modulates and rotates to form polarized light that can be reflected by the polarized light combiner.
  • the outgoing light of the first light source 111 is polarized light that can be transmitted by the polarizing light combiner, so the image light of the outgoing light of the first light source 111 scanned by the scanning device 112 on the virtual imaging plane 113 can also be transmitted by the polarizing light combiner. Therefore, in this embodiment, the first image light modulated by the low-frequency image display module 110 and the second image light modulated by the high-frequency image display module 120 are transmitted and reflected by the polarizing beam combiner, respectively, and the combined light enters the lens 150 .
  • the light deflection amplitude of the scanning device 112 needs to be adjusted so that the deviation angle of the first image light is smaller than that of the lens 150
  • the light receiving angle is such that the image of the first image light on the lens 150 is the same as the image size of the second image light on the lens.
  • the optical paths between the virtual imaging plane 113 and the lens 150 and between the spatial light modulator 124 and the lens 150 are equal. It should be noted that "equal" can be mathematically completely equal, or there can be a slight gap, so that when the first image light and the second image light are combined on the screen, they can be ignored by the visual persistence effect of the human eye .
  • FIG. 3 is a schematic structural diagram of a projection system 200 according to another preferred embodiment of the present invention.
  • the projection system 200 in this embodiment is substantially the same as the projection system 100 in the previous embodiment, and also includes a low-frequency image display module 210, a high-frequency image display module 220, an image signal processing module 230, a light combining module 240, and a lens 250.
  • the low-frequency image display module 210 also includes a first light source 211, a scanning device 212, a virtual imaging surface 213, and a scanning control unit 214.
  • the high-frequency image display module 220 also includes a second light source 221, a second polarizer 222, a light collection guide 223, and a spatial light modulator 224.
  • the light combining module 240 is also a polarizing light combiner, used to transmit incident light of a certain polarization state while reflecting incident light of another polarization state, and the outgoing light of the first light source 211 is polarized light that can be transmitted by the polarizing light combiner 241 .
  • the spatial light modulator 224 is specifically a DMD modulator, and the second light source 221 and the DMD modulator are located in the same polarization combiner On the side, the light emitted from the second light source 221 is converted into polarized light perpendicular to the polarization state of the first light source 211 by the second polarizer 222.
  • the image light emitted after modulation by the low-frequency image display module 210 and the image light emitted after modulation by the high-frequency image display module 220 are respectively transmitted and reflected by the polarizing light combiner 241 and then enter the lens 250 after being combined.
  • the projection system 200 in this embodiment is different from the projection system 100 in the previous embodiment in that the light collection guide device 223 includes a reflecting mirror 2231 and a TIR prism 2232, and the light emitted by the second light source 221 passes through the reflecting mirror 2231 And TIR prism 2232 enters the DMD modulator.
  • the spatial light modulator 224 may also use an LCD panel.
  • FIG. 4 is a flowchart of the projection method provided by the present invention.
  • the invention also provides a projection method suitable for the projection system 100 (200) in any of the above embodiments, including the following steps:
  • the image signal processing module 130 (230) is used to decompose the input image into a low-frequency image signal and a high-frequency image signal;
  • S20 Send the low-frequency image signal to the scan control unit 114 (214) of the low-frequency image display module 110 (210) to control the brightness of the first light source 111 (211) and the position status of the scanning device, so as to scan at the preset position to form the first An image light, at the same time, the high-frequency image signal is sent to the spatial light modulator 124 (224) of the high-frequency image display module 120 (220) to modulate the outgoing light of the second light source 121 (221) to form a second image light;
  • S30 Use the light combining module 140 (240) to combine the first image light and the second image light and output the light to the lens 150 (250).
  • the frequency of the image reflects the change speed of the image pixels, that is to say, if the image pixels in a certain area change very much, then the area carries certain high-frequency information.
  • the more high-frequency information in the image the more detailed features the image carries, and the high-resolution spatial light modulator 124 (224) is required for display.
  • the low-frequency image display module is easier to implement.
  • FIG. 5 is a flowchart of the image signal processing module 130 (230) decomposing the input image signal in the projection method shown in FIG.
  • the process of the image signal processing module 130 (230) splitting the input image into a low-frequency image signal and a high-frequency image signal is as follows:
  • S102 Perform corrosion operation on the RGB channel to reduce the highlight area of the picture
  • the image frequency is less than or equal to the truncated negative value f c and blooming, the output low-frequency image signal 110 to the low frequency image display module (210) scanning control unit 114 (214);
  • S105 Cut off the negative value of the signal whose image frequency is greater than f c and highlight overflow, and output a high-frequency image signal to the spatial light modulator 124 (224) of the high-frequency image display module 120 (220).
  • step S104 according to the maximum brightness of the scan display in the low-frequency image display module 110 (210), the pixels exceeding the maximum brightness and the negative value are truncated so as not to exceed the dynamic range of the scan display.
  • step S105 according to the maximum brightness that the spatial light modulator 124 (224) can output, the pixels exceeding the maximum brightness and the negative value are cut off. It should be noted that step S104 and step S105 can be performed simultaneously.
  • a polarizer is used to make the polarization state of the first image light formed by scanning at a predetermined position different from the polarization state of the second image light formed by the spatial light modulator 124 (224) as the light combining module
  • the 140 (240) polarizing light combiner respectively transmits and reflects the first image light and the second image light to combine light.
  • a polarizer is used to make the polarization state of the first image light formed at the preset position perpendicular to the polarization state of the second image light formed by the spatial light modulator 124 (224).

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Abstract

本发明涉及一种投影系统及投影方法。投影系统包括：图像信号处理模块，用于根据预设规则将输入的图像信号分解为低频图像信号与高频图像信号；低频图像显示模块，所述低频图像显示模块包括第一光源、扫描装置及扫描控制单元，所述扫描控制单元根据所述低频图像信号控制所述第一光源的亮度及所述扫描装置的位置状态，从而在预设位置扫描形成第一图像光；高频图像显示模块，所述高频图像显示模块包括第二光源及空间光调制器，所述空间光调制器根据所述高频图像信号对所述第二光源的出射光进行调制以形成第二图像光；及合光模块，用于将第一图像光及所述第二图像光进行合光后输出到镜头。本发明提供的投影系统及投影方法能够提高画面亮度和分辨率。

Description

投影系统及投影方法 技术领域
本发明涉及投影显示领域，尤其涉及一种投影系统及投影方法。
背景技术
目前的投影系统基本上都是利用均匀照明光源照明空间光调制器，由空间光调制器上的光阀阵列控制显示画面每个像素的灰阶以输出图像。然而空间光调制器能承受的最大光功率限制了输出图像的分辨率和亮度。一般来说，获得更高的亮度需要更大的空间光调制器以降低功率密度。但是增大的空间光调制器增加了投影系统的体积，也增加了成本。另外，有些空间光调制器采用硅基液晶等有机材料，在高温和高光功率密度条件下发生分解等反应，使其耐受的光功率密度受到限制。
除了空间光调制器，还有的投影系统通过扫描器件(如振镜、扫描镜等)动态的改变激光束的方向，使其在屏幕上扫描形成画面。这种投影系统不需要复杂的光学元件，结构简单，光利用效率高，但是受光斑大小及光源调制速度的限制，无法显示高分辨率的图像。要达到空间光调制器的主流分辨率，其光束的准直性和光斑尺寸需要做到非常小，一般的多模激光器光束质量达不到要求，只能使用单模激光器，这大大限制了扫描式投影系统的输出亮度和分辨率。
发明内容
为解决现有投影系统输出亮度和分辨率受限的技术问题，本发明提供一种能够显示高亮度、高分辨率图像的投影系统，包括图像信号处理模块，用于根据预设规则将输入的图像信号分解为低频图像信号与高频图像信号；低频图像显示模块，所述低频图像显示模块包括第 一光源、扫描装置及扫描控制单元，所述扫描控制单元根据所述低频图像信号控制所述第一光源的亮度及所述扫描装置的位置状态，从而在预设位置扫描形成第一图像光；高频图像显示模块，所述高频图像显示模块包括第二光源及空间光调制器，所述空间光调制器根据所述高频图像信号对所述第二光源的出射光进行调制以形成第二图像光；及合光模块，用于将所述第一图像光及所述第二图像光进行合光后输出到镜头。
在一个实施方式中，所述合光模块为偏振合光器，用于透射某一偏振态的入射光同时反射另一偏振态的入射光。
在一个实施方式中，所述第一图像光与所述第二图像光的偏振态相互垂直。
在一个实施方式中，所述第一图像光的偏离角度小于所述镜头的收光角度，且所述第一图像光在所述镜头上的成像与所述第二图像光在所述镜头上的成像大小相同。
在一个实施方式中，所述预设位置与所述镜头之间及所述空间光调制器与所述镜头之间的光程相等。
在一个实施方式中，述第一光源为激光光源，所述第二光源为激光光源、激光荧光光源、LED光源及灯泡光源中的任意一种。
在一个实施方式中，所述预设规则为：将所述图像信号中图像频率小于或等于f c的信号提取为所述低频图像信号、大于f c的信号提取为所述高频图像信号；f c＝f*(r s/r o)，其中，f为输入图像的最大频率，r o为原始图像分辨率，r s为所述第一图像光对应的分辨率。
本发明还提供一种适用于上述投影系统的投影方法，包括以下步骤：采用图像信号处理模块将输入的图像信号分解为低频图像信号与高频图像信号；将所述低频图像信号输送至低频图像显示模块的扫描控制单元以控制第一光源的亮度及扫描装置的位置状态，从而在预设位置扫描形成第一图像光，同时，将所述高频图像信号输送至高频图像显示模块的空间光调制器以调制第二光源的出射光形成第二图像光；及采用合光模块将所述第一图像光与所述第二图像光进行合光后 输出到镜头。
在一个实施方式中，采用图像信号处理模块将输入的图像信号分解为低频图像信号与高频图像信号包括以下步骤：输入图像；对RGB信道做腐蚀操作；根据预设的截至频率f c对腐蚀后的图像进行低频滤波；将图像频率小于或等于f c的信号根据所述低频图像显示模块中扫描显示的最大亮度截断负值和高光溢出获得所述低频图像信号，输出所述低频图像信号给所述低频图像显示模块；将图像频率大于f c的信号根据所述空间光调制器能输出的最大亮度截断负值和高光溢出获得所述高频图像信号，输出所述高频图像信号给所述高频图像显示模块。
在一个实施方式中，对腐蚀后的图像进行低频滤波采用的所述截止频率f c满足以下公式：f c＝f*(r s/r o)，其中，f为输入图像的最大频率，r o为原始图像分辨率，r s为所述第一图像光对应的分辨率。
本发明提供的投影系统通过图像信号处理模块将输入的图像分解为低频图像信号与高频图像信号，采用扫描式低频图像显示模块根据低频图像信号调制形成第一图像光，空间光调制器作为高频图像显示模块根据高频图像信号调制形成第二图像光，最后将第一图像光与第二图像光叠加还原出原始图像。与现有技术相比较，本发明将扫描式投影显示和基于空间光调制器的投影显示相结合，相对减少了入射到空间光调制器的光通量，从而提高了空间光调制器的使用寿命。
附图说明
图1是本发明提供的投影系统的原理框图。
图2是本发明一较佳实施方式的投影系统的结构示意图。
图3是本发明另一较佳实施方式的投影系统的结构示意图。
图4是本发明提供的投影方法的流程图。
图5是图4所示的投影方法中图像信号处理模块将输入的图像进行分解的流程图。
主要元件符号说明
投影系统          100、200
低频图像显示模块  110、210
第一光源          111、211
扫描装置          112、212
虚拟成像面        113、213
扫描控制单元      114、214
高频图像显示模块  120、220
第二光源          121、221
激光器            1211
波长转换装置      1212
第二起偏器        122、222
光收集引导装置    123、223
聚光透镜          1231
中继透镜          1232
反射镜            2231
TIR棱镜           2232
空间光调制器      124、224
图像信号处理模块  130、230
合光模块          140、240
镜头              150、250
如下具体实施方式将结合上述附图进一步说明本发明。
具体实施方式
请参阅图1，图1是本发明提供的投影系统100的原理框图。该投影系统100包括低频图像显示模块110、高频图像显示模块120、图像信号处理模块130、合光模块140及镜头150。其中，图像信号处理模块130能够根据预设规则将输入的图像信号分解为低频图像信号与高频图像信号，并将低频图像信号输送给低频图像显示模块110、高 频图像信号输送给高频图像显示模块120。低频图像显示模块110依据低频图像信号获得的第一图像光与高频图像显示模块120依据高频图像信号获得的第二图像光经合光模块140合光后进入镜头150。
具体地，上述预设规则为：将图像信号中图像频率小于或等于f c的信号提取为低频图像信号、大于f c的信号提取为高频图像信号，其中，f c作为截止频率满足以下公式：f c＝f*(r s/r o)，f为输入图像的最大频率，r o为原始图像分辨率，r s为第一图像光对应的分辨率。
请参阅图2，图2是本发明一较佳实施方式的投影系统100的结构示意图。本实施方式中，低频图像显示模块110包括第一光源111、扫描装置112、虚拟成像面113及扫描控制单元114。扫描装置112设置于第一光源111与虚拟成像面113之间的光路中，第一光源111、扫描装置112分别与扫描控制单元114相连并受扫描控制单元114控制。
低频图像显示模块110的工作原理在于：扫描控制单元114根据低频图像信号控制第一光源111的亮度及扫描装置112的位置状态，从而在预设位置扫描形成第一图像光。具体地，第一光源111的出射光经扫描装置112扫描在虚拟成像面113上形成虚拟图像，扫描控制单元114根据扫描装置112的位置状态推算入射光斑的实时位置并根据入射光斑的实时位置控制第一光源111的亮度从而在虚拟成像面113上产生明暗分布的图像。
本实施方式中，第一光源111包括多种单色光源，优选为RGB激光，且出射光为准直性好的偏振光。在其它实施方式中，不限制第一光源111为偏振光，低频图像显示模块110还包括第一起偏器，以改变第一光源111的出射光的偏振态，从而使第一图像光为具有一定偏振态的偏振光。
扫描装置112为高速扫描器件，如振镜、扫描镜等，能够周期性地快速改变入射光的方向，使第一光源111的出射光在虚拟成像面13处快速的扫描。
本实施方式中，高频图像显示模块120包括第二光源121、第二 起偏器122、光收集引导装置123及空间光调制器124。第二起偏器122与光收集引导装置123设置于第二光源121与空间光调制器124之间的光路中。高频图像显示模块120的工作原理在于：第二光源121的出射光经第二起偏器122转换为偏振光并被光收集引导装置123引导进入空间光调制器124进行调制。
具体地，第二光源121为均匀照明光源，可以是激光荧光混合光源、灯泡光源及LED光源中的任意一种。本实施方式中，第二光源121为激光荧光混合光源，其包括激光器1211及波长转换装置1212，可以理解，激光器1211能够产生激发光，如蓝激光，激光器1211产生的激发光入射至波长转换装置1212上能够通过激发荧光粉产生荧光，如红荧光、绿荧光，波长转换装置1212的出射光为依时序出射的激光与荧光的混合光。
本实施方式中，光收集引导装置123包括聚光透镜1231及中继透镜1232，其中，聚光透镜1231用于收集第二光源121的出射光，在第二光源121为大角度光源时十分必要。中继透镜1232用于将第二光源121的出射光中继到空间光调制器124中。
本实施方式中，空间光调制器124具体为LCOS空间光调制器，合光模块140具体为偏振合光器，能够透射某一偏振态的入射光同时反射另一偏振态的入射光。第二光源121与LCOS空间光调制器位于偏振合光器相对的两侧，第二光源121的出射光经第二起偏器122转换成能够被偏振合光器透射的偏振光，之后经过LCOS空间光调制器调制旋转后形成能够被偏振合光器反射的偏振光。
第一光源111的出射光为能够被偏振合光器透射的偏振光，因此第一光源111的出射光经过扫描装置112扫描在虚拟成像面113的图像光也能够被偏振合光器透射。所以本实施方式中，低频图像显示模块110调制后出射的第一图像光与高频图像显示模块120调制后出射的第二图像光在分别被偏振合光器透射、反射后合光进入镜头150。
为使低频图像显示模块110产生的第一图像光与高频图像显示模块120产生的第二图像光完全重合，需调整扫描装置112的光偏转幅 度，使第一图像光的偏离角度小于镜头150的收光角度，以使第一图像光在镜头150上的成像与第二图像光在镜头上的成像大小相同。此外，虚拟成像面113与镜头150之间及空间光调制器124与镜头150之间的光程相等。需要说明的是，“相等”可以是数学上的完全相等，也可以有一定微小差距，使得第一图像光与第二图像光在屏幕上合光时能够被人眼的视觉暂留效应所忽略。
请参阅图3，图3是本发明另一较佳实施方式的投影系统200的结构示意图。本实施方式中的投影系统200与上一实施方式中的投影系统100大致相同，同样包括低频图像显示模块210、高频图像显示模块220、图像信号处理模块230、合光模块240及镜头250。其中，低频图像显示模块210同样包括第一光源211、扫描装置212、虚拟成像面213及扫描控制单元214。高频图像显示模块220同样包括第二光源221、第二起偏器222、光收集引导装置223及空间光调制器224。合光模块240同样为偏振合光器，用于透射某一偏振态的入射光同时反射另一偏振态的入射光，第一光源211的出射光为能够被偏振合光器241透射的偏振光。
本实施方式中的投影系统200与上一实施方式中的投影系统100的不同之处在于：空间光调制器224具体为DMD调制器，第二光源221与DMD调制器位于偏振合光器的同一侧，第二光源221的出射光经第二起偏器222转换成与第一光源211偏振态相互垂直的偏振光。
因此，低频图像显示模块210调制后出射的图像光与高频图像显示模块220调制后出射的图像光在分别被偏振合光器241透射、反射后合光进入镜头250。
本实施方式中的投影系统200与上一实施方式中的投影系统100的不同之处还在于：光收集引导装置223包括反射镜2231及TIR棱镜2232，第二光源221的出射光经过反射镜2231及TIR棱镜2232后进入DMD调制器。
另外，空间光调制器224也可以采用LCD面板。
请参阅图4，图4是本发明提供的投影方法的流程图。本发明还 提供一种适用于上述任一实施方式中的投影系统100(200)的投影方法，包括以下步骤：
S10：采用图像信号处理模块130(230)将输入的图像分解为低频图像信号与高频图像信号；
S20：将低频图像信号输送至低频图像显示模块110(210)的扫描控制单元114(214)以控制第一光源111(211)的亮度及扫描装置的位置状态，从而在预设位置扫描形成第一图像光，同时，将高频图像信号输送至高频图像显示模块120(220)的空间光调制器124(224)以调制第二光源121(221)的出射光形成第二图像光；
S30：采用合光模块140(240)将第一图像光与第二图像光进行合光后输出到镜头150(250)。
需要说明的是，图像的频率反映了图像像素变化的快慢，也就是说，若某一区域图像像素变化得非常大，那么该区域就携带有一定的高频信息。而图像的高频信息越多，图像所携带的细节特征也就越多，需要采用高分辨率的空间光调制器124(224)进行显示。
另外，通过采用分辨率较低的扫描装置作为低频图像显示模块，使得低频图像显示模块更容易实现。
请一并参阅图5，图5是图4所示的投影方法中图像信号处理模块130(230)将输入的图像信号进行分解的流程图。图像信号处理模块130(230)将输入的图像进行拆分成低频图像信号与高频图像信号的流程具体如下：
S101：输入图像；
S102：对RGB信道做腐蚀操作以减小画面的高光区域；
S103：根据预设的截至频率f c对腐蚀后的图像进行低频滤波，其中，截止频率f c满足以下公式：f c＝f*(r s/r o)，f为输入图像的最大频率，r o为原始图像分辨率，r s为第一图像光对应的分辨率；
S104：将图像频率小于或等于f c进行截断负值和高光溢出，输出低频图像信号给低频图像显示模块110(210)的扫描控制单元114(214)；
S105：将图像频率大于f c的信号截断负值和高光溢出，输出高频图像信号给高频图像显示模块120(220)的空间光调制器124(224)。
具体地，步骤S104中，根据低频图像显示模块110(210)中扫描显示的最大亮度，对超出最大亮度和负值的像素进行截断处理，使其不超出扫描显示的动态范围。步骤S105中，根据空间光调制器124(224)能输出的最大亮度，对超出最大亮度和负值的像素进行截断处理。需要说明的是，步骤S104与步骤S105可以同时进行。
在一个具体实施方式中，采用起偏器使预设位置扫描形成的第一图像光的偏振态不同于空间光调制器124(224)调制形成的第二图像光的偏振态，作为合光模块140(240)的偏振合光器分别对第一图像光与第二图像光透射、反射进行合光。优选地，采用起偏器使预设位置形成的第一图像光的偏振态垂直于空间光调制器124(224)调制形成的第二图像光的偏振态。
以上仅为本发明的实施方式，并非因此限制本发明的专利范围，凡是利用本发明说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其它相关的技术领域，均同理包括在本发明的专利保护范围内。

Claims (10)

  1. 一种投影系统，其特征在于，包括：
    图像信号处理模块，用于根据预设规则将输入的图像信号分解为低频图像信号与高频图像信号；
    低频图像显示模块，所述低频图像显示模块包括第一光源、扫描装置及扫描控制单元，所述扫描控制单元根据所述低频图像信号控制所述第一光源的亮度及所述扫描装置的位置状态，从而在预设位置扫描形成第一图像光；
    高频图像显示模块，所述高频图像显示模块包括第二光源及空间光调制器，所述空间光调制器根据所述高频图像信号对所述第二光源的出射光进行调制以形成第二图像光；及
    合光模块，用于将所述第一图像光及所述第二图像光进行合光后输出到镜头。
  2. 如权利要求1所述的投影系统，其特征在于，所述合光模块为一偏振合光器，用于透射某一偏振态的入射光同时反射另一偏振态的入射光。
  3. 如权利要求2所述的投影系统，其特征在于，所述第一图像光与所述第二图像光的偏振态相互垂直。
  4. 如权利要求1所述的投影系统，其特征在于，所述第一图像光的偏离角度小于所述镜头的收光角度，且所述第一图像光在所述镜头上的成像与所述第二图像光在所述镜头上的成像大小相同。
  5. 如权利要求1所述的投影系统，其特征在于，所述预设位置与所述镜头之间及所述空间光调制器与所述镜头之间的光程相等。
  6. 如权利要求1所述的投影系统，其特征在于，所述第一光源为激光光源，所述第二光源为激光光源、激光荧光光源、LED光源及灯泡光源中的任意一种。
  7. 如权利要求1所述的投影系统，其特征在于，所述预设规则为：将所述图像信号中图像频率小于或等于f c的信号提取为所述低频图像信号、大于f c的信号提取为所述高频图像信号；f c＝f*(r s/r o)，其中， f为输入图像的最大频率，r o为原始图像分辨率，r s为所述第一图像光对应的分辨率。
  8. 一种投影方法，其特征在于，包括以下步骤：
    采用图像信号处理模块将输入的图像信号分解为低频图像信号与高频图像信号；
    将所述低频图像信号输送至低频图像显示模块的扫描控制单元以控制第一光源的亮度及扫描装置的位置状态，从而在预设位置扫描形成第一图像光，同时，将所述高频图像信号输送至高频图像显示模块的空间光调制器以调制第二光源的出射光形成第二图像光；及
    采用合光模块将所述第一图像光与所述第二图像光进行合光后输出到镜头。
  9. 如权利要求8所述的投影方法，其特征在于，采用图像信号处理模块将输入的图像信号分解为低频图像信号与高频图像信号包括以下步骤：
    输入图像；
    对RGB信道做腐蚀操作；
    根据预设的截至频率f c对腐蚀后的图像进行低频滤波；
    将图像频率小于或等于f c的信号根据所述低频图像显示模块中扫描显示的最大亮度截断负值和高光溢出获得所述低频图像信号，输出所述低频图像信号给所述低频图像显示模块；
    将图像频率大于f c的信号根据所述空间光调制器能输出的最大亮度截断负值和高光溢出获得所述高频图像信号，输出所述高频图像信号给所述高频图像显示模块。
  10. 如权利要求9所述的投影方法，其特征在于，对腐蚀后的图像进行低频滤波采用的所述截止频率f c满足以下公式：f c＝f*(r s/r o)，其中，f为输入图像的最大频率，r o为原始图像分辨率，r s为所述第一图像光对应的分辨率。
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