WO2018192130A1 - 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
WO2018192130A1
WO2018192130A1 PCT/CN2017/094794 CN2017094794W WO2018192130A1 WO 2018192130 A1 WO2018192130 A1 WO 2018192130A1 CN 2017094794 W CN2017094794 W CN 2017094794W WO 2018192130 A1 WO2018192130 A1 WO 2018192130A1
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WO
WIPO (PCT)
Prior art keywords
image data
light
illumination light
grayscale value
luminous flux
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PCT/CN2017/094794
Other languages
English (en)
French (fr)
Inventor
胡飞
郭祖强
杜鹏
李屹
Original Assignee
深圳市光峰光电技术有限公司
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Application filed by 深圳市光峰光电技术有限公司 filed Critical 深圳市光峰光电技术有限公司
Priority to JP2019556586A priority Critical patent/JP7090101B2/ja
Priority to EP17905978.7A priority patent/EP3611566B1/en
Priority to US16/605,366 priority patent/US11228742B2/en
Publication of WO2018192130A1 publication Critical patent/WO2018192130A1/zh

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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
    • H04N9/315—Modulator illumination systems
    • H04N9/3152—Modulator illumination systems for shaping the light beam
    • 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
    • H04N9/315—Modulator illumination systems
    • H04N9/3155—Modulator illumination systems for controlling the light source
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/005—Projectors using an electronic spatial light modulator but not peculiar thereto
    • G03B21/008—Projectors using an electronic spatial light modulator but not peculiar thereto using micromirror devices
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2053—Intensity control of illuminating light
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/208—Homogenising, shaping of the illumination light
    • 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
    • H04N9/315—Modulator illumination systems
    • H04N9/3158—Modulator illumination systems for controlling the spectrum
    • 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 a projection system and a projection method.
  • Existing projection systems generally include a light source device, a spatial light modulator (such as an LCOS spatial light modulator or a DMD spatial light modulator), and a projection lens, the light source device emitting three colors of light such as red, green and blue, and the spatial light modulator is based on Image data modulating light emitted by the light source device, the projection lens projecting image light output by the spatial light modulator to display a projected image, however, existing projection systems may have a low contrast condition. It is necessary to improve.
  • a spatial light modulator such as an LCOS spatial light modulator or a DMD spatial light modulator
  • the present invention provides a projection system and a projection method with higher contrast.
  • a signal processor configured to receive image data, the image data comprising a plurality of grayscale values, wherein each grayscale value corresponds to one pixel, the signal processor is further configured to grayscale a plurality of pixels of the image data Increase in order value;
  • An optical relay system for providing the illumination light to the DMD such that the DMD can modulate the projection light required to obtain the projected image
  • an adjusting unit configured to reduce a luminous flux of the illumination light supplied to the DMD when the grayscale value of the plurality of pixels of the image data is increased, a ratio of the luminous flux of the illumination light to be smaller and the image data The proportion of the grayscale value is increased;
  • DMD configured to modulate the adjusted photo according to the image data after the grayscale value is increased Bright light to produce the projection light required to project an image
  • the brightness of the projected light matches the image data before the grayscale value is increased.
  • the signal processor receives the image data, the image data includes a sub-frame image data, and the signal processing determines whether a highest grayscale value of each pixel in the sub-frame image data is less than a preset value, when the highest grayscale value of each pixel in the subframe image data is smaller than the preset value, the signal processor controls to increase a grayscale value of each pixel of the subframe image data,
  • the illuminating device adjusts the luminous flux of the illumination light to be smaller than the standard luminous flux Lo when the highest grayscale value of each pixel in the sub-frame image data is smaller than the preset value; when the highest pixel of each pixel in the sub-frame image data
  • the grayscale value is greater than or equal to the preset value, the signal processor keeps the grayscale value of each pixel of the subframe image data unchanged and provides the subframe image data to the DMD,
  • the illumination device emits illumination light of the standard luminous flux Lo, and the DMD modulates the illumination light of the standard luminous flux Lo according to the sub
  • the gray level maximum value achievable by the projection system is Gmax
  • the preset value is set to GR
  • the preset value GR is less than or equal to the gray level maximum value Gmax.
  • the preset value is 90% of the gray scale maximum value Gmax.
  • the signal processor further calculates an adjustment coefficient k when the highest grayscale value of each pixel in the subframe image data is less than the preset value, wherein the adjustment coefficient k is equal to Gmax/GL And GL represents a highest grayscale value of each pixel in the image data of the subframe, and the signal processor adjusts a grayscale value of each pixel of the image data to each of the image data according to the adjustment coefficient k.
  • the luminous flux of the illumination light emitted by the light-emitting device is adjusted to be 1/k of the standard luminous flux Lo by k times the grayscale value of the pixel.
  • the adjusting component is further configured to adjust a luminous flux of the illumination light emitted by the light source.
  • the adjustment component is configured to reduce a divergence angle of illumination light provided by the optical relay system, increase an F-number of illumination light provided by the optical relay system, and reduce the optical The luminous flux of the illumination light provided by the system.
  • the adjustment component includes an adjustable aperture, the adjustable aperture Provided at an aperture stop of the optical relay system; the adjustable aperture is for blocking a peripheral portion of a light beam of illumination light incident to the adjustable aperture such that illumination light exiting the adjustable aperture The divergence angle with respect to the incident illumination light becomes small, the F number increases, and the luminous flux decreases.
  • the optical relay system includes a light homogenizing component for homogenizing the illumination light;
  • the adjustment component includes a liquid crystal lens, the liquid crystal lens is located on the optical path before the light homogenizing component Light emitted from the liquid crystal lens is incident on an incident surface of the light homogenizing member; the liquid crystal lens is configured to reduce a divergence angle of the illumination light such that the illumination light beam is projected onto an incident surface of the light homogenizing member
  • the cross-sectional area at the time of the position is larger than the area of the incident surface such that the divergence angle of the illumination light entering the light-shaping member is reduced, the F-number is increased, and the luminous flux is decreased.
  • a projection method comprising the following steps:
  • the image data includes a plurality of grayscale values, wherein each grayscale value corresponds to one pixel;
  • Providing illumination light wherein a luminous flux of the illumination light is reduced, wherein a ratio of a decrease in a luminous flux of the illumination light is adapted to a ratio of an increase in a grayscale value of the image data;
  • a projection image is generated according to the projection light, wherein a brightness of the projection light matches an image data before the grayscale value is increased.
  • the grayscale value of each pixel in the image data when the highest grayscale value of each pixel in the image data is less than a preset value, the grayscale value of each pixel of the image data is increased; when the sub The highest grayscale value of each pixel in the frame image data is greater than or equal to the preset value, and the grayscale value of each pixel of the subframe image data is kept unchanged, and the luminous flux of the illumination light is controlled to be a standard luminous flux Lo.
  • the illumination light of the standard luminous flux Lo is modulated according to the image data with the grayscale value unchanged to generate projection light required for projecting the image.
  • the grayscale maximum value achievable by the projection system using the method is Gmax
  • the preset value is set to GR
  • the preset value is GR. Less than or equal to the gray scale maximum value Gmax.
  • the preset value is 90% of the grayscale maximum value Gmax.
  • an adjustment coefficient k is calculated when a highest grayscale value of each pixel in the subframe image data is smaller than the preset value, wherein the adjustment coefficient k is equal to Gmax/GL , GL represents the highest grayscale value of each pixel in the sub-frame image data.
  • the grayscale value of each pixel of the image data is adjusted to k times of the grayscale value of each pixel of the image data according to the adjustment coefficient k, that is, The grayscale value of any pixel of the image data is Gi, and the increased grayscale value corresponding to the grayscale value Gi of the pixel of the image data is k*Gi, and the luminous flux of the illumination light is adjusted. It is 1/k of the standard luminous flux Lo, that is, the luminous flux of the illumination light is Lo/k.
  • the grayscale value of the plurality of pixels of the image data is increased, and the luminous flux of the illumination light is decreased, thereby increasing the grayscale value according to the method.
  • the image data modulates the illumination light with reduced luminous flux to generate projection light, and the proportion of the light flux of the illumination light is adjusted to be proportional to the ratio of the grayscale value of the image data, so that the image data can be accurately restored.
  • the original grayscale value of the plurality of pixels is also increased due to the increase of the grayscale value, and the "ON" time of each mirror of the DMD is increased, and the "OFF" time is decreased, thereby reducing the miscellaneous "OFF” time.
  • Astigmatism reduces the effect of stray light on the contrast of the projection system, resulting in improved contrast of the projection system and projection method.
  • Figure 1 is a schematic diagram of a test screen for ANSI contrast.
  • FIG. 2 is a schematic structural view of a DMD.
  • Fig. 3 is a schematic view showing the optical path of stray light generated when the mirror unit of the DMD is in the "OFF" state.
  • Figure 4 is the ratio of stray light generated by illumination light of different divergence angles on the same DMD. On the map.
  • Figure 5 is a schematic illustration of the definition of the divergence angle of light.
  • Fig. 6 is a schematic structural view of a projection system according to a first embodiment of the present invention.
  • FIG. 7 is a schematic diagram of projection timing of the projection system of FIG. 6.
  • Fig. 8 is a schematic structural view of a projection system according to a second embodiment of the present invention.
  • Fig. 9 is a schematic view showing the adjustment of the illumination light by the adjusting member shown in Fig. 8.
  • Figure 10 is a flow chart of the projection method of the present invention.
  • the contrast of the projection system generally refers to the ratio of the total white field center illuminance value to the total black field center illuminance value in a fixed projection picture.
  • usually Ground in the black field, you can directly turn off the power to falsely increase the contrast, so there is a definition of ANSI contrast, which is tested in a picture, showing 4*4 all black and white areas (as shown in Figure 1), and tested under this screen to obtain an ANSI contrast CR, specifically, the ANSI contrast CR conforms to the following formula.
  • E bright represents the central illuminance of the white area
  • E black represents the central illuminance of the black area
  • E la represents the central illuminance of the ambient light when the white area is not projected
  • E ba represents the central illuminance of the ambient light when the black area is not projected.
  • the brightness perception range that is common and suitable in daily life is about 0.01-1000 nits, and the contrast is about 100000:1, while the normal spatial light modulator can modulate much less than the human eye. range.
  • the pursuit of projection display images is to hope to be as close as possible to the human eye's perception of the natural environment. HDR technology has been proposed to improve the dynamic range of projection display systems.
  • FIG. 2 is a schematic structural view of a DMD including a substrate 101 and a plurality of matrix-arranged mirror units 102 disposed on the substrate 101, and the substrate 101 (such as a silicon substrate) is internally configured.
  • a drive circuit may be provided for controlling the mirror unit 102 to rotate rapidly,
  • Each of the mirror units 102 is an optical switch whose flip time is on the order of microseconds, and each mirror unit 102 may include an "ON" state (ie, an on state) and an "OFF" state (ie, an off state),
  • the human eye actually integrates the brightness of its "ON” state, and the longer the "ON” state (or the shorter the "OFF” state) the higher the brightness.
  • the time of the "ON” state or the "OFF” state of each mirror unit 102 is controlled by the grayscale value of its corresponding pixel. The higher the grayscale, the longer the "ON” state, the "OFF” "The shorter the state.
  • a pixel has a red grayscale value of 127, and the corresponding mirror unit 102 has an "OFF" state time ratio of 1/2.
  • the grayscale value is increased to 191, the corresponding mirror unit 102 is "OFF" state time.
  • the ratio is 1/4.
  • the illumination light is incident on the DMD surface at a certain angle.
  • the mirror unit 102 of the DMD is in the “ON” state, the light reflected by the mirror unit 102 of the DMD enters the lens and is finally projected onto the screen;
  • the mirror unit 102 of the DMD is in the "OFF” state, the mirror unit 102 of the DMD is flipped and the reflected light is prevented from entering the lens.
  • FIG. 3 is a schematic diagram of the optical path of stray light generated when the mirror unit 102 of the DMD is in the "OFF" state.
  • illumination light is incident on the substrate 101 from a gap between two adjacent mirror units 102, and is repeatedly reflected between the substrate 101 and the back of the mirror unit 102 to generate stray light.
  • the stray light may leak out of the edge of the mirror unit 102 resulting in a reduced contrast of the projection system employing the DMD.
  • FIG. 4 is an alignment diagram of stray light generated by illumination light of different divergence angles on the same DMD.
  • the left side is a schematic diagram of stray light generated by illumination light having a large divergence angle (small F number) on the DMD, and the right side is a miscellaneous divergence angle (larger F-number) illumination light that is incident on the DMD.
  • a astigmatism diagram One of ordinary skill in the art will appreciate that the divergence angle of the light is used to measure the velocity at which the beam diverges outward from the beam waist.
  • the beam divergence angle is the derivative of the beam radius to the axial position of the far field, that is, The distance from the waist is much larger than the Rayleigh length.
  • the gap between the mirror units becomes large, and the illumination light is incident on the bottom substrate 101 and repeatedly reflected therein to form stray light, wherein adjacent The area irradiated by the stray light between the mirror units 102 is a stray light area, and the divergence angle of the illumination light is larger (the smaller the F number), the more stray light, the greater the influence on the contrast of the projection system, that is, the corresponding The more the contrast of the projection system is reduced, as shown in Fig. 4, in the "OFF" state, the illumination light with a large left divergence angle produces significantly more stray light than the illumination light with a smaller right divergence angle. Therefore, the contrast of the projection system corresponding to the illumination light having a large left divergence angle is smaller than the contrast of the projection system corresponding to the illumination light having a smaller right divergence angle.
  • the divergence angle of the illumination light should be controlled as small as possible, that is, the light flux of the illumination light is controlled to be low, that is, no light enters the lens and is projected onto the screen.
  • eliminating the time division of the DMD mirror unit 102 in the "OFF" state, or reducing the "OFF" state of the time ie, increasing the image signal value or grayscale value, will help to enhance the projection The contrast of the system.
  • FIG. 6 is a schematic structural diagram of a projection system 100 capable of improving image contrast according to the first embodiment of the present invention.
  • the projection system 100 includes a light emitting device 110, a DMD, a signal source 120, and a signal processor 130.
  • the illumination device 110 is for emitting illumination light and providing the illumination light to the DMD.
  • the signal source 120 is configured to provide image data to be displayed to the signal processor 130, the image data comprising a plurality of grayscale values, wherein each grayscale value corresponds to one pixel.
  • the signal processor 130 is configured to increase grayscale values of a plurality of pixels of the image data and provide image data with increased grayscale values to the DMD.
  • the standard luminous flux of the illumination light emitted by the illumination device 110 is Lo
  • the illumination device 110 is further configured to reduce the luminous flux of the illumination light when the grayscale value of the plurality of pixels of the image data is increased, such as Adjusted to be smaller than the standard luminous flux Lo, the ratio of the proportion of the luminous flux of the illumination light to the grayscale value of the image data is increased
  • the illumination device 110 provides the adjusted illumination light to the DMD.
  • the DMD modulates the adjusted illumination light according to the image data after the grayscale value is increased to generate projection light required for projecting an image, wherein a brightness of the projection light and an image before the grayscale value is increased The data matches.
  • the signal processor 130 increases the grayscale value of a plurality of pixels of the image data, and the light emitting device 110 can reduce the luminous flux of the illumination light.
  • the DMD modulates the illumination light with reduced luminous flux according to the image data with the increased grayscale value to generate projection light, which can not only accurately restore the original grayscale value of the plurality of pixels of the image data, but also
  • the increase of the order value causes the "ON" time of each mirror of the DMD to increase, and the "OFF" time decreases, thereby reducing the stray light generated by the "OFF" time, and reducing the influence of stray light on the contrast of the projection system, so that The contrast of the projection system 100 is increased.
  • the light-emitting device 110 correspondingly reduces the luminous flux of the illumination light refers to adjusting the luminous flux of the illumination light to be smaller than the standard luminous flux Lo emitted when the illumination device 110 does not perform the luminous flux adjustment.
  • the standard luminous flux Lo When the grayscale value of each pixel of the image data has substantially reached the grayscale maximum value and is difficult to be further improved, the signal processor 130 does not need to perform enhancement processing on the image data but maintain the image data.
  • the grayscale value of each pixel is unchanged, and the image data (ie, the original image data) whose grayscale value is unchanged is directly supplied to the DMD, and at the same time, the illumination device 110 directly emits the illumination of the standard luminous flux Lo.
  • the DMD generates projection light according to the illumination light that modulates the standard luminous flux Lo with the original image data.
  • the image data may be a sub-frame image data, where the sub-frame image data may be red sub-frame image data, green sub-frame image data or blue sub-frame image data, and the signal processor 130 may When the highest grayscale value in each pixel in the subframe image data is lower than a preset value, the grayscale value of the plurality of pixels of the subframe image data is increased, and the grayscale value is increased Frame image data is provided to the DMD.
  • the sub-frame image data may be red sub-frame image data, green sub-frame image data or blue sub-frame image data
  • the signal processor 130 may When the highest grayscale value in each pixel in the subframe image data is lower than a preset value, the grayscale value of the plurality of pixels of the subframe image data is increased, and the grayscale value is increased Frame image data is provided to the DMD.
  • the light emitting device 110 further reduces the luminous flux of the illumination light when the highest grayscale value in each pixel of the sub-frame image data is lower than a preset value, so that the luminous flux of the adjusted illumination light and the gray
  • the image data after the order value is increased is adapted.
  • the illuminating device The set 110 can include a drive component 140 and an adjustment component 150, wherein the drive component 140 controls the adjustment component 150 to illuminate the illumination light emitted by the illumination device.
  • the driving component 140 of the light emitting device 110 may directly analyze the image data to determine whether the signal processor 130 increases the grayscale value of each pixel of the image data according to the image data.
  • the driving component 140 of the light emitting device 110 determines that the signal processor 130 increases the grayscale value of each pixel of the image data according to the image data, and the driving component 140 of the light emitting device 110 controls the adjusting component.
  • 150 is corresponding to reducing the luminous flux of the illumination light.
  • the driving component 140 of the illumination device 110 may analyze whether the highest grayscale value in each pixel of the image data is lower than the preset value, when The highest grayscale value in each pixel of the image data is lower than the preset value, and the driving component 140 of the light emitting device 110 controls the adjusting component 150 to correspondingly reduce the luminous flux of the illumination light.
  • the driving component 140 of the light emitting device 110 may receive a light flux adjustment control signal that is sent by the signal processor 130 when the grayscale value of each pixel of the image data is raised, and then the The driving component 140 of the light emitting device 110 can control the adjusting component 150 to reduce the luminous flux of the illumination light according to the light flux adjustment signal sent by the signal processor 130.
  • the signal processor 130 may analyze whether a highest grayscale value in each pixel of the image data is smaller than the preset value, when a highest grayscale value in each pixel of the image data is smaller than the preset When the value is set, the signal processor 130 increases the grayscale value of the plurality of pixels of the image data, and provides image data with the grayscale value increased to the DMD, and also sends the luminous flux adjustment signal to The driving component 140 of the light emitting device 110 causes the driving component 140 of the light emitting device 110 to control the adjusting component 150 to reduce the luminous flux of the illumination light according to the light flux adjustment signal.
  • the signal processor 130 keeps the grayscale value of each pixel of the subframe image data unchanged and
  • the sub-frame image data is supplied to the DMD, the illumination device 110 emits illumination light of the standard luminous flux Lo, and the DMD modulates the standard luminous flux Lo according to the sub-frame image data with the grayscale value unchanged.
  • the illumination light produces the projection light required to project the image.
  • the gray scale range that the projection system 100 can display is 0 to G Max , such as 0 to (2 m -1) gray scale, where m can be 8, and the gray scale range can be 0 to 255.
  • G Max represents the gray scale maximum that the projection system 100 can display.
  • the signal processor 130 may analyze the highest grayscale value G L in each pixel of the image data, wherein it may be understood that the highest grayscale value is generally less than or equal to the grayscale maximum value G Max and The highest grayscale value G L is compared with the preset value G R , wherein the preset value G R may also be less than or equal to the grayscale maximum value G Max , if the preset value is the The grayscale maximum value GMax is 90%, that is, when the grayscale maximum value is 255 grayscale, the preset value may be 230 grayscale.
  • the signal processor 130 calculates an adjustment coefficient k, and increases a grayscale value of each pixel of the image data according to the adjustment coefficient k, Image data with increased grayscale values is supplied to the DMD.
  • the adjustment coefficient k may be equal to the maximum grayscale value G Max / the maximum grayscale value G L, G L since the maximum grayscale values of the image data is generally less than maximum grayscale value G Max Therefore, the k is controlled to adjust the grayscale value of each pixel of the image data to k times, and the original grayscale value of any pixel in the image data is G. i , the grayscale value of the adjusted pixel is kG i .
  • the driving component 140 of the light emitting device 110 may control the adjusting component 150 to adjust the luminous flux of the illumination light to the grayscale value of each pixel of the image data according to the adjustment coefficient k.
  • the signal processor 130 may send a light flux adjustment signal representing the adjustment coefficient k to the driving component of the light emitting device according to the adjustment coefficient k, and the driving component 140 of the light emitting device 110 may be controlled according to the adjustment coefficient k
  • the adjusting component 150 adjusts the luminous flux of the illumination light to match the grayscale value of each pixel that increases the image data.
  • the light-emitting device 110 adjusts the luminous flux of the illumination light according to the adjustment coefficient k, and adjusts the luminous flux of the illumination light to 1/k of the original luminous flux, that is, the adjusted luminous flux emitted by the illumination device 110 is a standard luminous flux.
  • Each of the mirror units of the DMD receives illumination light having a luminous flux of L 0 /k, and modulates the illumination light having the luminous flux of L 0 /k according to the adjusted grayscale value kG i to generate projection light, the projection light
  • the luminous flux is kG i *L 0 /k, which is the same as the luminous flux obtained by modulating the original luminous flux L 0 according to the original grayscale value G i is G i *L 0
  • the projection light emitted by each mirror unit of the DMD The gray scale value of each pixel of the image data is accurately restored.
  • one frame of image data includes red sub-frame image data, green sub-frame image data, and blue sub-frame image data, and the original red of one pixel is set in the one-frame image data.
  • the grayscale value, the original green grayscale value, and the original blue grayscale value are respectively (50, 60, 80), and the adjustment system can be set to 2 times, whereby the signal processor 130 is configured according to the
  • the adjustment coefficient adjusts the red grayscale value, the green grayscale value, and the blue grayscale value of the pixel to twice the original, that is, (100, 120, 160), and the luminous flux of the illumination light can be adjusted to Half of the original illumination, or 50%, also accurately restores the grayscale of the image data.
  • the light emitting device 110 may include a light source module 111 and an optical relay system 112.
  • the light source module 111 emits illumination light
  • the optical relay system 112 is configured to use the illumination light.
  • the optical path change, the uniform light, and the like are performed, and the processed illumination light is supplied to the DMD.
  • the light-emitting device 110 may be configured to set the light flux of the illumination light, that is, the adjustment component 150 is disposed in the light source module 111, and the adjustment component 150 may be a light source driving circuit for The driving current of the light emitting element (such as a laser) of the light source module 111 is adjusted to change the luminous flux of the illumination light; however, in another embodiment, the light emitting device 110 may also pass through the optical relay system 112.
  • the light emitting device 110 changes the The luminous flux of the illumination light emitted by the light source module is adjusted in combination with the divergence angle (or the F number of the illumination light) of the illumination light in the optical relay system 112, and the luminous flux of the illumination light is adjusted, respectively,
  • the adjusting component 150 is in the light source module 111 and the optical relay system 112.
  • the light emitting device 110 may reduce the divergence angle of the illumination light provided by the optical relay system 112, increase the F number of the illumination light provided by the optical relay system 112, and reduce the optical relay.
  • the optical relay system 112 of the light-emitting device 110 is mainly described by changing the divergence angle of the illumination light (or the F-number of illumination light) to adjust the luminous flux of the illumination light.
  • the luminous flux of the illumination light emitted by the light-emitting device 110 is the standard luminous flux L 0
  • the reference divergence angle of the illumination light emitted by the illumination device 110 is ⁇ .
  • the light emitting device 110 adjusts the divergence angle of the illumination light according to the adjustment coefficient to Less than the reference divergence angle (or adjusting the F number of the illumination light to be greater than the reference F number F), and the ratio between the divergence angle of the adjusted illumination light and the reference divergence angle
  • the ratio between the F number of the adjusted illumination light and the reference F number F is proportional to the adjustment coefficient k
  • the smaller the ratio between the divergence angle of the adjusted illumination light and the reference divergence angle is (the ratio between the F number of the adjusted illumination light and the reference F number F is larger), that is, The divergence angle of the adjusted illumination light is smaller (the F number of the adjusted illumination light is larger).
  • the light-emitting device 110 can adjust the luminous flux of the illumination light by changing the F-number of the illumination light. Specifically, when the luminous flux of the illumination light emitted by the light-emitting device is the standard luminous flux L 0 , the corresponding F-number of the illumination light emitted by the illumination device 110 is the reference F-number F. When the grayscale value of each pixel of the image data is increased, the light emitting device 110 adjusts the F number of the illumination light to be greater than the reference F number F according to the adjustment coefficient. And the F number of the adjusted illumination light and the reference F number F.
  • the ratio between the ratio is proportional to the adjustment coefficient k, that is, the larger the adjustment coefficient k, the smaller the ratio between the divergence angle of the adjusted illumination light and the reference divergence angle, and the adjustment The F number of the subsequent illumination light is the reference F number F.
  • the optical relay system 112 is provided with the adjusting component 150, and the adjusting component 150 adjusts the location of the optical relay system 112 when the grayscale value of each pixel of the image data is increased. Deriving the divergence angle (or F number) of the illumination light, increasing the F number of the illumination light provided by the optical relay system, and reducing the luminous flux of the illumination light provided by the optical relay system, such that the luminous flux of the illumination light Compatible with the image data after the grayscale value is increased, and the luminous flux of the illumination light is adapted to the image data after the grayscale value is increased.
  • the larger the divergence angle of the mirror unit 102 irradiated to the DMD ie, the smaller the F number
  • the larger the stray light region i.e., the influence of stray light on the contrast of the projection system.
  • the stray light it is also possible to reduce the stray light area by reducing the divergence angle, further improving the contrast.
  • the optical relay system 112 further includes an optical system 113, a light homogenizing device 114, and a relay system 115 that are sequentially disposed.
  • the light source module 111 emits illumination light to the optical system 113.
  • the light source module 111 may include a light emitting element for emitting excitation light, and the wavelength conversion element may be a color wheel provided with a wavelength conversion material such as a fluorescent material (red, yellow, a green fluorescent material or the like) for receiving the excitation light and converting a part of the excitation light into a laser light, thereby emitting the laser light and another part of the excitation light as the illumination light.
  • the illuminating element may comprise a laser source, such as a blue laser source, and the excitation light may comprise a laser, such as a blue laser.
  • the optical system 113 is configured to collect and illuminate illumination light emitted by the light source module 111 and direct the illumination light to the light homogenizing device 114.
  • the light homogenizing device 114 is configured to homogenize illumination light emitted by the optical system 113 and provide the dimmed illumination light to the relay system 115.
  • the homogenizer The piece 114 may include a light-diffusing square rod, the illumination light emitted by the optical system 113 enters the square rod through the entrance of the square rod, and the illumination light is homogenized by specular reflection or total internal reflection on the inner wall of the square rod. The illuminating light after the uniform light is emitted from the exit of the square bar. It will be appreciated that in alternative embodiments, the light homogenizing device 114 may also include a fly-eye lens.
  • the relay system 115 is configured to provide the dimmed illumination light to the DMD.
  • the relay system 115 mainly includes some relay lenses 116, and the illumination light of the light homogenizing device 114 (square rod or compound eye) is provided to the DMD surface at an angle.
  • the adjustment component 150 may be disposed in the relay system 115.
  • the adjusting component 150 is an adjustable aperture for changing a divergence angle, an F number, and a luminous flux of the illumination light, and the adjustable aperture may be disposed at an aperture stop of the relay system 115.
  • the adjustable aperture is for blocking a peripheral portion of the light beam of the illumination light incident to the adjustable aperture such that the divergence angle of the illumination light emitted from the adjustable aperture relative to the incident illumination light becomes smaller, F The number increases and the luminous flux decreases.
  • the driving component 140 may include a driving motor that can drive the adjustable aperture to control a divergence angle, an F number, and a luminous flux of the illumination light.
  • the magnitude of the divergence angle reduction and the F number increase depends on the magnitude of the required reduced luminous flux, and in the present embodiment, the incident depending on the adjustable aperture occlusion is incident to the
  • the amount of illumination light of the adjustable aperture that is, the aperture size of the adjustable aperture, that is, the degree to which the divergence angle needs to be reduced according to the magnitude of the decrease of the luminous flux, thereby adjusting the aperture of the adjustable aperture
  • the size is such that the adjustable aperture controls the divergence angle to an angle that requires adjustment.
  • the relay system 115 includes a relay lens 116.
  • the main optical axis of the edge light of the light homogenizing device 114 such as a square bar
  • the main light of the edge light emitted by the light homogenizing device 114 The intersection of the axis with the central axis of the relay system 115 is the position of the aperture stop.
  • the center of the adjustable aperture of the adjustment member 150 coincides with the central axis of the relay system 115 and is placed vertically.
  • the position of the main optical axis of the edge ray emitted by the light concentrating device 114 may be defined by the relay lens 116, such as the upper edge ray of the light concentrating device 114 is incident on the rear through the relay lens 116.
  • the adjustable aperture of the adjusting component 150 may have an actual thickness but the influence on the adjustment of the F number is very small and can be ignored. Therefore, the effect of the actual thickness of the adjustable aperture may not be considered here. It suffices to coincide with the position where the adjustable aperture is located and the position of the aperture stop.
  • FIG. 7 is a timing diagram of the operation of the projection system 100.
  • the signal source 120 provides image data to be displayed to the signal processor 130, and the signal processor 130 analyzes the image data, and the image data includes a first subframe image.
  • a highest grayscale value of the plurality of pixels of the first subframe image data reaches a grayscale maximum value Gmax (eg, 255 grayscale), that is, greater than or equal to the preset value (eg, 230 gray scale), the highest grayscale value (such as 228 grayscale) of the plurality of pixels of the second subframe image data does not reach the grayscale maximum value Gmax (such as 255 grayscale) and is also smaller than the pre- Set a value (such as 230 grayscale), that is, greater than or equal to the preset value (such as 230 grayscale).
  • Gmax eg, 255 grayscale
  • the signal processor 130 determines that the first subframe image data does not need to be further determined according to the highest grayscale value (such as 255 grayscale) of the plurality of pixels of the first subframe image data.
  • the grayscale enhancement processing is performed, and the signal processor 130 supplies the first subframe image data (i.e., the original first subframe image data) to the DMD in a first period of time.
  • the driving component 140 also determines or receives the signal output by the signal processor 130 according to the image data to know that the adjustment of the luminous flux is not required, and the driving component 140 controls the adjusting component 150 to maintain the luminous flux of the illumination light.
  • the standard luminous flux Lo is supplied to the DMD of the standard luminous flux Lo.
  • the DMD modulates the illumination light of the standard luminous flux Lo according to the original first sub-frame image data to obtain projection light.
  • the highest grayscale value of the plurality of pixels of the second subframe image data such as 228 grayscale, lower than the preset value 230 grayscale
  • the driving component 140 also determines or receives the signal output by the signal processor 130 according to the image data to know that the adjustment of the luminous flux is required, and the driving component 140 controls the adjusting component 150 to adjust the luminous flux of the illumination light to
  • the 1/k of the standard luminous flux Lo is supplied to the DMD only for the luminous flux of only 1/k of the standard luminous flux Lo.
  • the DMD modulates the illumination light of the light flux of the Lo/k according to the second sub-frame image data after the gray scale is increased to obtain projection light.
  • the signal processor 130 increases the grayscale value of the plurality of pixels of the image data
  • the light emitting device 110 reduces the luminous flux of the illumination light
  • the DMD increases the grayscale according to the
  • the image data of the value modulates the illumination light with the reduced luminous flux to generate projection light
  • the proportion of the light flux of the illumination light is adjusted to be proportional to the ratio of the grayscale value of the image data, so that the image data can be accurately restored.
  • the original grayscale value of the plurality of pixels also due to the increase of the grayscale value, the "ON" time of each mirror of the DMD is increased, and the "OFF" time is decreased, thereby reducing the "OFF” time. Stray light reduces the effect of stray light on the contrast of the projection system 100, resulting in improved contrast of the projection system 100.
  • FIG. 8 is a schematic structural diagram of a projection system 200 capable of improving image contrast according to a second embodiment of the present invention.
  • the projection system 200 of the second embodiment is substantially the same as the projection system 100 of the first embodiment, that is, the above description of the projection system 100 for the first embodiment is basically applicable to the second embodiment.
  • the projection system 200 is mainly different in that: in the second embodiment, the adjustment member 250 is disposed in the optical system 223, and the adjustment member 250 is a liquid crystal lens, and the driving member 240 controls the illumination light through the liquid crystal lens. Divergence angle, F number, and luminous flux.
  • the liquid crystal lens may be the last lens of the optical system, and the driving component 240 may control the arrangement of the liquid crystals in the liquid crystal lens by the change of the driving voltage, so that the refractive index of the liquid crystal lens changes. Further, the focal length of the liquid crystal lens is also changed, so that the divergence angle, the F number, and the luminous flux of the illumination light are changed.
  • the cross-sectional area of the light beam of the illumination light incident on the incident surface position of the light-homogenizing device 214 is larger than that of the light-harvesting device 214.
  • the area of the incident surface that is, the area of the cross section of the illumination light beam incident on the incident surface position of the light homogenizing device 214 by the adjustment member 250, such that the cross-sectional area of the illumination light beam is larger than
  • the area of the incident surface of the homogenizing device 214 is such that the luminous flux of the illumination light is adjusted to be smaller than the standard luminous flux.
  • the magnitude of the decrease of the divergence angle and the increase of the F number depends on the magnitude of the reduced luminous flux, that is, how much the divergence angle needs to be reduced according to the magnitude of the decrease of the luminous flux, Thereby the cross-sectional area of the light beam is beyond the area of the entrance face of the light homogenizing device 214.
  • the focal lengths of the liquid crystal lenses before and after the adjustment are greater than the distance between the liquid crystal lens and the incident surface of the light homogenizing member 114. Because, if it is smaller, dimming the divergence angle of the illumination light does not increase the cross section of the light beam incident on the incident surface of the light homogenizing member 114, as shown in FIG. 9, if the focal length of the liquid crystal lens is smaller than the liquid crystal lens and the uniform light The distance of the member 114, after the divergence angle of the illumination light is adjusted to be small, the cross section of the spot incident on the incident surface of the light-homogenizing device 114 is rather smaller.
  • FIG. 9 is a flowchart of a projection method of the present invention.
  • the projection method of the present invention can be applied to the projection systems 100 and 200 of the first and second embodiments described above.
  • the projection method may include the following steps S1, S2, S3, S4, and S5.
  • Step S1 Receive image data, wherein the image data includes a plurality of grayscale values, wherein each grayscale value corresponds to one pixel.
  • the step S1 may be performed by the signal processor 130, that is, the signal processor 130 may receive image data sent by the signal source 120.
  • step S2 the grayscale values of the plurality of pixels of the image data are increased.
  • step S2 the grayscale value of each pixel of the image data may be analyzed, and when the highest grayscale value of each pixel of the image data is less than a preset value, the image data is The grayscale value of each pixel is increased.
  • the step S2 may be performed by the signal processor 130, that is, the signal processor 130 receives image data sent by the signal source 120, and analyzes the highest grayscale value of each pixel of the image data. Dangdang When the highest grayscale value of each pixel of the image data is smaller than the preset value, the signal processor 130 increases the grayscale value of each pixel of the image data.
  • the image data may be a sub-frame image data, where the sub-frame image data may be red sub-frame image data, green sub-frame image data or blue sub-frame image data, and the signal processor 130 may When the highest grayscale value in each pixel in the subframe image data is lower than the preset value, the grayscale value of each pixel of the subframe image data is increased, and the grayscale value is increased. Sub-frame image data is supplied to the DMD.
  • the projection system 100, 200 using the projection method can display a gray scale range of 0 to G Max , such as 0 to (2 m -1) gray scale, where m can be 8,
  • the gray scale range may be 0 to 255 gray scales
  • G Max represents the gray scale maximum values that the projection systems 100, 200 can display.
  • the signal processor 130 may analyze the highest grayscale value G L in each pixel of the image data, wherein it may be understood that the highest grayscale value is generally less than or equal to the grayscale maximum value G Max and The highest grayscale value G L is compared with the preset value G R , wherein the preset value G R may also be less than or equal to the grayscale maximum value G Max , if the preset value is the The grayscale maximum value Gmax is 90%, that is, when the grayscale maximum value is 255 grayscale, the preset value may be 230 grayscale.
  • the step S2 may further include the following steps: calculating an adjustment coefficient, and increasing gray of each pixel of the image data according to the adjustment coefficient.
  • the adjustment coefficient k may be equal to the maximum grayscale value G Max / the maximum grayscale value G L, G L since the maximum grayscale values of the image data is generally less than maximum grayscale value G Max Therefore, the k is greater than or equal to 1, the signal processor 130 controls to adjust the grayscale value of each pixel of the image data to k times, and sets the original grayscale value of any pixel in the image data.
  • G i the gray scale value of the adjusted pixel is kG i .
  • one frame of image data includes red sub-frame image data, green sub-frame image data, and blue sub-frame image data, and the original red of one pixel is set in the one-frame image data.
  • the grayscale value, the original green grayscale value, and the original blue grayscale value are respectively (50, 60, 80), and the adjustment system can be set to 2 times, whereby the signal processor 130 is configured according to the
  • the adjustment coefficient adjusts the red grayscale value, the green grayscale value, and the blue grayscale value of the pixel to twice the original, that is, (100, 120, 160), and the luminous flux of the illumination light can be adjusted to Half of the original illumination, or 50%, also accurately restores the grayscale of the image data.
  • step S3 illumination light is provided to reduce the luminous flux of the illumination light, wherein the proportion of the luminous flux of the illumination light is adjusted to be proportional to the ratio of the grayscale value of the image data.
  • the step S3 can be performed by the light emitting device.
  • Step S4 modulating the illumination light of the reduced light flux according to the image data after the grayscale value is increased to generate projection light required for projecting the image.
  • the step S3 can be performed by the DMD.
  • the step S3 may include the step of adjusting the luminous flux of the illumination light to be smaller than the standard luminous flux when the highest grayscale value in each pixel of the image data is lower than a preset value, so that the The luminous flux of the adjusted illumination light is adapted to the image data after the grayscale value is increased.
  • the light emitting device 110 may include a driving part 140 and an adjusting part 150, wherein the driving part 140 controls the adjusting part 150 to perform luminous flux adjustment on the illumination light emitted by the light emitting device 110.
  • the driving component 140 of the light emitting device 110 may directly analyze the image data to determine whether the signal processor 130 increases the grayscale value of each pixel of the image data according to the image data.
  • the driving component 140 of the light emitting device 110 determines that the signal processor 130 increases the grayscale value of each pixel of the image data according to the image data, and the driving component 140 of the light emitting device 110 controls the adjusting component.
  • 150 is corresponding to reducing the luminous flux of the illumination light.
  • the driving component 140 of the illumination device 110 may analyze whether the highest grayscale value in each pixel of the image data is lower than the preset value, when The highest grayscale value in each pixel of the image data is lower than the preset value, and the driving component 140 of the light emitting device 110 controls the adjusting component 150 to correspondingly reduce the luminous flux of the illumination light.
  • the driving component 140 of the light emitting device 110 can be connected. Receiving, by the signal processor 130, a light flux adjustment control signal that is emitted when the grayscale value of each pixel of the image data is raised, and further, the driving component 140 of the light emitting device 110 can be based on the luminous flux emitted by the signal processor 130. The adjustment signal controls the adjustment component 150 to correspondingly reduce the luminous flux of the illumination light.
  • the signal processor 130 may analyze whether a highest grayscale value in each pixel of the image data is lower than the preset value, when a highest grayscale value in each pixel of the image data is lower than
  • the signal processor 130 increases the grayscale value of the plurality of pixels of the image data, and provides the image data after the grayscale value is increased to the DMD, and also transmits the luminous flux adjustment.
  • the signal is transmitted to the driving component of the light emitting device, so that the driving component 140 of the light emitting device 110 controls the adjusting component to adjust the light flux of the illumination light correspondingly according to the light flux adjustment signal.
  • the driving component 140 of the light emitting device 110 may control the adjusting component 150 to adjust the luminous flux of the illumination light to the grayscale value of each pixel of the image data according to the adjustment coefficient k.
  • the signal processor 130 may send a light flux adjustment signal representing the adjustment coefficient k to the driving component 140 of the light emitting device 110 according to the adjustment coefficient k, and the driving component 140 of the light emitting device 110 may be according to the adjustment coefficient.
  • k controlling the adjustment component 150 to adjust the luminous flux of the illumination light to be adapted to the grayscale value of each pixel that increases the image data.
  • the adjusting component 150 may be an adjustable aperture disposed in the relay system 115 of the light emitting device 110 for changing the illumination light.
  • a divergence angle or an F-number of the illumination light
  • the adjustable aperture may be disposed at an aperture stop of the relay system 115, the adjustable aperture being used to block incident to the adjustable
  • the peripheral portion of the light beam of the illumination light of the aperture is such that the divergence angle of the illumination light emitted from the adjustable aperture relative to the incident illumination light becomes smaller, the F number is increased, and the luminous flux is decreased.
  • the drive component 140 can include a drive motor that can drive the adjustable aperture to control the divergence angle of the illumination light.
  • the magnitude of the divergence angle reduction and the F number increase depends on the magnitude of the required reduced luminous flux, and in the present embodiment, the incident depending on the adjustable aperture occlusion is incident to the The amount of illumination light of the adjustable aperture, that is, the aperture size of the adjustable aperture, that is, how much the divergence angle needs to be reduced according to the magnitude of the reduction of the luminous flux, Thereby adjusting the aperture size of the adjustable aperture such that the adjustable aperture controls the divergence angle to an angle that needs to be adjusted.
  • the relay system 115 includes a relay lens 116.
  • the main optical axis of the edge light of the light homogenizing device 114 such as a square bar
  • the main light of the edge light emitted by the light homogenizing device 114 The intersection of the axis with the central axis of the relay system 115 is the position of the aperture stop.
  • the center of the adjustable aperture coincides with the central axis of the relay system 115 and is placed vertically.
  • the position of the main optical axis of the edge ray emitted by the light concentrating device 114 may be defined by the relay lens 116, such as the upper edge ray of the light concentrating device 114 is incident on the rear through the relay lens 116.
  • the adjustable aperture may have an actual thickness but the influence on the adjustment of the F number is very small and can be ignored. Therefore, the influence of the actual thickness of the adjustable aperture may not be considered here, and only It is preferable that the position where the adjustable aperture is located coincides with the position of the aperture stop.
  • the adjustment member 150 may be disposed in the optical system 113, and the adjustment member 150 is a liquid crystal lens, and the driving member 140 controls the liquid crystal lens.
  • the divergence angle, F-number, and luminous flux of the illumination light may be the last lens of the optical system, and the driving component 140 may control the arrangement of the liquid crystals in the liquid crystal lens by the change of the driving voltage, so that the refractive index of the liquid crystal lens changes. Further, the focal length of the liquid crystal lens also changes, so that the divergence angle, the F number, and the luminous flux of the illumination light are changed.
  • the cross-sectional area of the light beam of the illumination light incident on the incident surface position of the light-homogenizing device 214 is larger than that of the light-harvesting device 214.
  • the area of the incident surface that is, the area of the cross section of the illumination light beam incident on the incident surface position of the light homogenizing device 214 by the adjustment member 250, such that the cross-sectional area of the illumination light beam is larger than
  • the area of the incident surface of the light homogenizing device 214 is adjusted to adjust the luminous flux of the illumination light to a small The standard luminous flux.
  • the magnitude of the decrease of the divergence angle and the increase of the F number depends on the magnitude of the reduced luminous flux, that is, how much the divergence angle needs to be reduced according to the magnitude of the decrease of the luminous flux, Thereby the cross-sectional area of the light beam is beyond the area of the entrance face of the light homogenizing device 214.
  • the focal lengths of the liquid crystal lenses before and after the adjustment are greater than the distance between the liquid crystal lens and the incident surface of the light homogenizing member 114. Because, if it is smaller, dimming the divergence angle of the illumination light does not increase the cross section of the light beam incident on the incident surface of the light homogenizing member 114, as shown in FIG. 10, if the focal length of the liquid crystal lens is smaller than the liquid crystal lens and the uniform light The distance of the member 114, after the divergence angle of the illumination light is adjusted to be small, the cross section of the spot incident on the incident surface of the light-homogenizing device 114 is rather smaller.
  • the standard luminous flux of the illumination light emitted by the light-emitting device 110 is L 0
  • the projection light obtained by the DMD modulating the illumination light having the standard luminous flux L 0 according to the original gray scale value of the image data can exactly restore the gray scale of the image data.
  • the light-emitting device 110 adjusts the luminous flux of the illumination light according to the adjustment coefficient k, and adjusts the luminous flux of the illumination light to 1/k of the original luminous flux, that is, the adjusted luminous flux emitted by the illumination device is a standard luminous flux.
  • Each of the mirror units of the DMD receives illumination light having a luminous flux of L 0 /k, and modulates the illumination light having the luminous flux of L 0 /k according to the adjusted grayscale value kG i to generate projection light, the projection light
  • the luminous flux is kG i *L 0 /k, which is the same as the luminous flux obtained by modulating the original luminous flux L 0 according to the original grayscale value G i is G i *L 0
  • the projection of each mirror unit 102 of the DMD The light accurately restores the grayscale value of each pixel of the image data.
  • Step S5 generating a projection image according to the projection light, wherein the brightness of the projection light matches the image data before the grayscale value is increased.
  • the step S5 can be implemented by a projection lens, which can receive the projection light emitted by the DMD and project the projection light on the projection screen to display the projection image, because the luminous flux of the illumination light is small
  • the ratio is adapted to the ratio of the grayscale value of the image data being increased, so that the brightness of the projected light matches the image data before the grayscale value is increased.

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Abstract

一种投影系统（100、200），包括：信号处理器（130）、光源（111）、光学中继系统（112）、调节部件（150、250）及DMD。信号处理器（130）接受图像数据，图像数据包括多个灰阶值，其中每个灰阶值对应一个像素，信号处理器（130）将图像数据的多个像素的灰阶值提高。光源（111）用于发出照明光，光学中继系统（112）将照明光提供给DMD以使得DMD可调制得到投影图像所需要的投影光。调节部件（150、250）在图像数据的多个像素的灰阶值被提高时将提供至DMD的照明光的光通量调小，照明光的光通量调小的比例与图像数据的灰阶值提高的比例相适应。DMD依据灰阶值提高后的图像数据调制调整后的照明光，以产生投影图像所需要的投影光。还公开了一种投影方法。这种投影系统（100、200）的对比度较高。

Description

投影系统及投影方法 技术领域
本发明涉及一种投影系统及投影方法。
背景技术
现有投影系统一般包括光源装置、空间光调制器(如LCOS空间光调制器或DMD空间光调制器)及投影镜头，所述光源装置射出如红绿蓝三色光，所述空间光调制器依据图像数据对所述光源装置发出的光进行图像调制，所述投影镜头对所述空间光调制器输出的图像光进行投影以显示投影图像，然而，现有投影系统可能存在对比度较低的情形，有必要改善。
发明内容
为解决现有技术投影系统对比度较低的问题，本发明提供一种对比度较高的投影系统及投影方法。
一种投影系统，其包括
信号处理器，用于接收图像数据，所述图像数据包括多个灰阶值，其中每个灰阶值对应一个像素，所述信号处理器还用于将所述图像数据的多个像素的灰阶值提高；
光源，用于发出照明光，
光学中继系统，用于将所述照明光提供给DMD以使得DMD可调制得到投影图像所需要的投影光；
调节部件，用于在所述图像数据的多个像素的灰阶值被提高时将提供至所述DMD的照明光的光通量调小，所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应；及
DMD，用于依据所述灰阶值提高后的图像数据调制所述调整后的照 明光，以产生投影图像所需要的投影光；
所述投影光的亮度与所述灰阶值提高前的图像数据相匹配。
在一种实施方式中，所述信号处理器接收所述图像数据，所述图像数据包括一子帧图像数据，所述信号处理判断所述子帧图像数据中各像素的最高灰阶值是否小于预设值，当所述子帧图像数据中各像素的最高灰阶值小于所述预设值，所述信号处理器控制将所述子帧图像数据的各像素的灰阶值提高，所述发光装置在所述子帧图像数据中各像素的最高灰阶值小于所述预设值时将所述照明光的光通量调整为小于标准光通量Lo；当所述子帧图像数据中各像素的最高灰阶值大于或等于所述预设值，所述信号处理器将所述子帧图像数据的各像素的灰阶值保持不变并将所述子帧图像数据提供至所述DMD，所述发光装置发出所述标准光通量Lo的照明光，所述DMD依据所述灰阶值不变的子帧图像数据调制所述标准光通量Lo的照明光产生投影图像所需要的投影光。
在一种实施方式中，设所述投影系统可达到的灰阶极大值为Gmax，设所述预设值为GR，所述预设值GR小于等于所述灰阶极大值Gmax。
在一种实施方式中，所述预设值为所述灰阶极大值Gmax的90％。
在一种实施方式中，所述信号处理器还在所述子帧图像数据中各像素的最高灰阶值小于所述预设值时计算调整系数k，其中所述调整系数k等于Gmax/GL，GL代表所述子帧图像数据中各像素的最高灰阶值，所述信号处理器依据所述调整系数k将所述图像数据的各像素的灰阶值均调整至所述图像数据的各像素的灰阶值的k倍，所述发光装置发出的照明光的光通量则被调整为标准光通量Lo的1/k。
在一种实施方式中，所述调节部件还用于调整所述光源发出的照明光的光通量。
在一种实施方式中，所述调节部件用于减小所述光学中继系统提供的照明光的发散角、提高所述光学中继系统提供的照明光的F数，以及减少所述光学中继系统提供的照明光的光通量。
在一种实施方式中，所述调节部件包括可调光圈，所述可调光圈 设置于所述光学中继系统的孔径光阑处；所述可调光圈用于遮挡入射至所述可调光圈的照明光的光束的外围部分，以使得从所述可调光圈出射的照明光相对于入射的照明光的发散角变小、F数提高以及光通量减小。
在一种实施方式中，所述光学中继系统包括匀光部件，用于对所述照明光进行匀光；所述调节部件包括液晶透镜，所述液晶透镜位于所述匀光部件之前光路上，从所述液晶透镜出射的光照射至匀光部件的入射面；所述液晶透镜用于调小所述照明光的发散角，使得所述照明光束在投射至所述匀光部件的入射面位置时横截面面积大于所述入射面面积，以使得进入所述匀光部件的照明光的发散角减小、F数提高以及光通量减小。
一种投影方法，其包括如下步骤：
接收图像数据，其中所述图像数据包括多个灰阶值，其中每个灰阶值对应一个像素；
将所述图像数据的多个像素的灰阶值提高；
提供照明光，将所述照明光的光通量调小，其中所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应；
依据所述灰阶值提高后的图像数据调制所述调小后的光通量的照明光产生投影图像所需要的投影光；及
依据所述投影光产生投影图像，其中所述投影光的亮度与所述灰阶值提高前的图像数据相匹配。
在一种实施方式中，所述投影方法中，当所述图像数据中各像素的最高灰阶值小于预设值，则将所述图像数据的各像素的灰阶值提高；当所述子帧图像数据中各像素的最高灰阶值大于或等于所述预设值，将所述子帧图像数据的各像素的灰阶值保持不变，控制所述照明光的光通量为标准光通量Lo，依据所述灰阶值不变的图像数据调制所述标准光通量Lo的照明光产生投影图像所需要的投影光。
在一种实施方式中，所述投影方法中，设使用所述方法的投影系统可达到的灰阶极大值为Gmax，设所述预设值为GR，所述预设值GR 小于等于所述灰阶极大值Gmax。
在一种实施方式中，所述投影方法中，所述预设值为所述灰阶极大值Gmax的90％。
在一种实施方式中，所述投影方法中，在所述子帧图像数据中各像素的最高灰阶值小于所述预设值时计算调整系数k，其中所述调整系数k等于Gmax/GL，GL代表所述子帧图像数据中各像素的最高灰阶值。
在一种实施方式中，所述投影方法中，依据所述调整系数k将所述图像数据的各像素的灰阶值均调整至所述图像数据的各像素的灰阶值的k倍，即设所述图像数据的任意一像素的灰阶值为Gi，则所述图像数据的像素的灰阶值Gi对应的提高后的灰阶值为k*Gi，所述照明光的光通量则被调整为所述标准光通量Lo的1/k，即所述照明光的光通量为Lo/k。
相较于现有技术，所述投影系统及投影方法中，将所述图像数据的多个像素的灰阶值提高，以及将所述照明光的光通量降低，进而依据所述提高了灰阶值的图像数据调制所述光通量降低的照明光产生投影光，所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应，不仅可以准确还原了所述图像数据的多个像素的原始灰阶值，还由于所述灰阶值的提高导致所述DMD每个反射镜的“ON”时间提高，而“OFF”时间减小，从而减少“OFF”时间产生的杂散光，减少杂散光对投影系统对比度的影响，使得所述投影系统及投影方法的对比度提高。
附图说明
图1是ANSI对比度的测试画面示意图。
图2是DMD的结构示意图。
图3是DMD的反射镜单元处于“OFF”状态时产生的杂散光的光路示意图。
图4是不同发散角的照明光照射到同一DMD上产生的杂散光的比 对图。
图5是光的发散角的定义示意图。
图6是本发明第一实施方式的投影系统的结构示意图。
图7是图6的投影系统的投影时序示意图。
图8是本发明第二实施方式的投影系统的结构示意图。
图9是图8所示的调节部件对照明光的调节示意图。
图10是本发明投影方法的流程图。
主要元件符号说明
投影系统        100、200、
反射镜单元      102
基板            101
发光装置        110
光源            111
光学中继系统  112
光学系统        113、223
匀光器件        114
中继系统        115
中继透镜        116
信号源          120
信号处理器      130
驱动部件        140、240
调节部件        150、250
步骤            S1～S5
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
首先，需要说明的是，对于投影系统的对比度，通常是指某一固定投影画面中，全白场中心照度值与全黑场中心照度值的比值。通常 地，在全黑场时，可以直接关闭电源来虚假地提高对比度，因此，还有一种ANSI对比度的定义，其测试方法是在一幅画面中，呈现4*4的全黑全白相间的区域(如图1所示)，并在此画面下测试获得ANSI对比度CR，具体地，所述ANSI对比度CR符合如下公式。
Figure PCTCN2017094794-appb-000001
其中Ebright代表白色区域的中心照度，Eblack代表黑色区域的中心照度，Ela代表白色区域未进行画面投影时环境光的中心照度，Eba代表黑色区域未进行画面投影时环境光的中心照度，i代表黑色区域与白色区域的编号(上述测试画面共包括8个黑色区域及8个白色区域，故i＝1至8)。
一般地，人们在日常生活中常见且比较适应的亮度感知范围大约是0.01-1000尼特，对比度为100000∶1左右，而正常的空间光调制器能调制的范围都远低于人眼的感知范围。人们对投影显示图像的追求是希望能尽量接近人眼对自然环境的感知，HDR技术被提出以提高投影显示系统的动态范围。
能够提高对比度的方法一般有三种：(1)保证一帧图像中最高亮度像素的亮度，降低其他像素的整体亮度；(2)保证一帧图像中最低亮度像素的亮度，提高其他像素的整体亮度；(3)保证一帧图像中介于最高亮度和最低亮度之间的某一像素的亮度，提高较高亮度像素的整体亮度，并降低较低亮度像素的整体亮度。由于一帧图像的最高亮度受到光源亮度及光学系统传递效率的限制，因此，降低暗像素的光亮度来提高对比度的方法更加快捷与灵活。
DMD(Digital Micro-mirror Device，数字微镜器件)是目前常用的空间光调制器，其为美国TI(Texas Instruments)公司开发的图像芯片，并被广泛地用于投影显示行业。如图2所示，图2是DMD的结构示意图，所述DMD包括基板101及设置于所述基板101上的多个矩阵排列的反射镜单元102构成，所述基板101(如硅基板)内部可以设置有驱动电路，用于控制所述反射镜单元102快速地转动，其 中每个反射镜单元102是一种光开关，其翻转时间为微秒量级，每个反射镜单元102可以包括“ON”状态(即开状态)与“OFF”状态(即关状态)，人眼其实是对其“ON”状态产生亮度的积分，“ON”状态的时间越长(或“OFF”状态的时间越短)亮度越高。每个反射镜单元102的“ON”状态或者“OFF”状态的时间由其对应的像素的灰阶值来控制，灰阶越高，所述“ON”状态的时间越长，所述“OFF”状态越短。例如，一个像素的红色灰阶值为127，对应的反射镜单元102“OFF”状态时间占比为1/2，当灰阶值增加到191时，对应的反射镜单元102“OFF”状态时间占比为1/4。
具体地，所述DMD工作时，照明光以一定的角度入射DMD表面，当DMD的反射镜单元102处于“ON”状态时，DMD的反射镜单元102反射的光进入镜头最终投影到屏幕上；当DMD的反射镜单元102处于“OFF”状态时，DMD的反射镜单元102翻转，反射的光线避免进入镜头。
然而，经研究发现，在DMD的反射镜单元102处于“OFF”状态时，由于反射镜单元102间的缝隙变大，照明光会入射其底部基板101并在其中反复反射产生杂散光并进入镜头，最终导致采用所述DMD的投影系统的对比度降低。具体地，请参阅图3，图3是DMD的反射镜单元102处于“OFF”状态时产生的杂散光的光路示意图。如图3所示，照明光从相邻两个反射镜单元102之间的缝隙射入所述基板101，并在所述基板101与所述反射镜单元102背部之间反复反射产生杂散光，所述杂散光可能从所述反射镜单元102边缘泄露出去而导致采用所述DMD的投影系统的对比度降低。
更进一步地，请参阅图4，图4是不同发散角的照明光照射到同一DMD上产生的杂散光的比对图。其中左侧是发散角较大(F数较小)的照明光照射到DMD上产生的杂散光示意图，右侧是发散角(F数较大)较小的照明光照射到DMD上产生的杂散光示意图。所述领域的一般技术人员可以理解，光的发散角是用来衡量光束从束腰向外发散的速度，具体地，光束发散角为光束半径对远场轴向位置的导数，也就 是与束腰的距离远大于瑞利长度，请参阅图5，图5是发散角的定义示意图，其中发散角θ＝tan(x/2L)，F数即F#＝1/2Sinθ，其中x代表光斑的直径，L代表测试光源到所述光斑的距离。
如图4所示，当DMD的反射镜单元102处于“OFF”状态时，反射镜单元之间的缝隙变大，照明光会入射其底部基板101并在其中反复反射形成杂散光，其中相邻反射镜单元102之间的杂散光照射到的区域为杂散光区域，并且照明光的发散角越大(F数越小)，杂散光越多，对投影系统对比度的影响就越大，即对应投影系统的对比度降低的越多，如图4所示，在“OFF”状态，左侧发散角较大的照明光产生的杂散光明显多于右侧发散角较小的照明光产生的杂散光，因此，左侧发散角较大的照明光对应的投影系统的对比度小于右侧发散角较小的照明光对应的投影系统的对比度。
因此，为了提高对比度，当DMD的反射镜单元102处于“OFF”状态时，应当尽量控制照明光的发散角较小，即控制所述照明光的光通量较低，即没有光进入镜头投影到屏幕上，也就是说，消除DMD的反射镜单元102在“OFF”状态下杂散光，或降低其“OFF”状态的时间占比(即提高图像信号值或灰阶值)，将有利于提升投影系统的对比度。
基于以上分析，本发明提供一种高动态对比度的投影系统100，请参阅图6，图6是本发明提供的第一实施方式的可提高图像对比度的投影系统100的结构示意图。所述投影系统100包括发光装置110、DMD、信号源120、及信号处理器130。所述发光装置110用于发出照明光，以及将所述照明光提供到所述DMD。所述信号源120用于提供待显示的图像数据至所述信号处理器130，所述图像数据包括多个灰阶值，其中每个灰阶值对应一个像素。所述信号处理器130用于将所述图像数据的多个像素的灰阶值提高、以及将灰阶值提高后的图像数据提供至所述DMD。所述发光装置110发出的照明光的标准光通量为Lo，所述发光装置110还用于在所述图像数据的多个像素的灰阶值被提高时将所述照明光的光通量调小，如调整为小于所述标准光通量Lo，所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例 相适应，所述发光装置110将调整后的照明光提供到所述DMD。所述DMD依据所述灰阶值提高后的图像数据调制所述调整后的照明光，以产生投影图像所需要的投影光，其中所述投影光的亮度与所述灰阶值提高前的图像数据相匹配。
相较于现有技术，所述投影系统100中，所述信号处理器130将所述图像数据的多个像素的灰阶值提高，所述发光装置110可以将所述照明光的光通量降低，所述DMD依据所述提高了灰阶值的图像数据调制所述光通量降低的照明光产生投影光，不仅可以准确还原了所述图像数据的多个像素的原始灰阶值，还由于所述灰阶值的提高导致所述DMD每个反射镜的“ON”时间提高，而“OFF”时间减小，从而减少“OFF”时间产生的杂散光，减少杂散光对投影系统对比度的影响，使得所述投影系统100的对比度提高。
可以理解，所述发光装置110对应调小所述照明光的光通量指的是以所述发光装置110不进行光通量调整时发出的标准光通量Lo为基准，将所述照明光的光通量调整为小于所述标准光通量Lo。当所述图像数据的各像素的灰阶值基本上已经达到灰阶极大值，难于进一步提高时，所述信号处理器130无需对所述图像数据进行提高处理而是保持所述图像数据的各像素的灰阶值不变，且将所述灰阶值不变的图像数据(即原始图像数据)直接提供至所述DMD，同时，所述发光装置110直接发出所述标准光通量Lo的照明光至所述DMD，所述DMD依据所述与原始的图像数据调制所述标准光通量Lo的照明光产生投影光。
具体地，所述图像数据可以为一子帧图像数据，其中所述子帧图像数据可以为红色子帧图像数据、绿色子帧图像数据或蓝色子帧图像数据，所述信号处理器130可以在所述子帧图像数据中的各像素中的最高灰阶值低于预设值时，将所述子帧图像数据的多个像素的灰阶值提高、以及将灰阶值提高后的子帧图像数据提供至所述DMD。
所述发光装置110还在所述子帧图像数据的各像素中的最高灰阶值低于预设值时调小所述照明光的光通量，使得所述调整后照明光的光通量与所述灰阶值提高后的图像数据相适应。具体地，所述发光装 置110可以包括驱动部件140与调节部件150，其中所述驱动部件140控制所述调节部件150对所述发光装置发出的照明光进行光通量调整。
在一种实施方式中，所述发光装置110的驱动部件140可以直接分析图像数据从而依据图像数据判断所述信号处理器130是否会将所述图像数据的各像素的灰阶值提高，若所述发光装置110的驱动部件140依据所述图像数据判断所述信号处理器130会将所述图像数据的各像素的灰阶值提高，则所述发光装置110的驱动部件140控制所述调节部件150对应调小所述照明光的光通量，具体地，所述发光装置110的驱动部件140可以分析所述图像数据的各像素中的最高灰阶值是否低于所述预设值，当所述图像数据的各像素中的最高灰阶值低于所述预设值，所述发光装置110的驱动部件140控制所述调节部件150对应调小所述照明光的光通量。
在另一种实施方式中，所述发光装置110的驱动部件140可以接收所述信号处理器130在调高所述图像数据的各像素的灰阶值时发出的光通量调整控制信号，进而所述发光装置110的驱动部件140可以依据所述信号处理器130发出的光通量调整信号控制所述调节部件150对应调小所述照明光的光通量。具体地，所述信号处理器130可以分析所述图像数据的各像素中的最高灰阶值是否小于所述预设值，当所述图像数据的各像素中的最高灰阶值小于所述预设值时，所述信号处理器130将所述图像数据的多个像素的灰阶值提高、以及将灰阶值提高后的图像数据提供至所述DMD，同时还发送所述光通量调整信号至所述发光装置110的驱动部件140，使得所述发光装置110的驱动部件140依据所述光通量调整信号控制所述调节部件150对应调小所述照明光的光通量。当所述子帧图像数据中各像素的最高灰阶值大于或等于所述预设值时，所述信号处理器130将所述子帧图像数据的各像素的灰阶值保持不变并将所述子帧图像数据提供至所述DMD，所述发光装置110发出所述标准光通量Lo的照明光，所述DMD依据所述灰阶值不变的子帧图像数据调制所述标准光通量Lo的照明光产生投影图像所需要的投影光。
具体地，设所述投影系统100可以显示的灰阶范围为0至GMax，如0至(2m-1)灰阶，其中，m可以为8，所述灰阶范围可以为0至255灰阶，GMax代表所述投影系统100可以显示的灰阶极大值。所述信号处理器130可以分析所述图像数据的各像素中的最高灰阶值GL，其中可以理解，所述最高灰阶值一般小于等于所述灰阶极大值GMax，并将所述最高灰阶值GL与所述预设值GR进行比较，其中，所述预设值GR也可以小于等于所述灰阶极大值GMax，如所述预设值为所述灰阶极大值GMax的90％，即，当所述灰阶极大值为255灰阶时，所述预设值可以为230灰阶。当所述最高灰阶值GL小于所述预设值GR时，所述信号处理器130计算调整系数k，以及依据所述调整系数k提高所述图像数据的各像素的灰阶值，并将灰阶值提高后的图像数据提供到所述DMD。具体地，所述调整系数k可以等于所述极大灰阶值GMax/所述最高灰阶值GL，由于所述图像数据的最高灰阶值GL一般小于极大灰阶值GMax，因此所述k大于等于1，所述信号处理器控制将所述图像数据的各像素的灰阶值均调整至k倍，设所述图像数据中的任意一像素的原始灰阶值为Gi，则调整后的所述像素的灰阶值为kGi。
具体地，所述发光装置110的驱动部件140可以依据所述调整系数k控制所述调节部件150将所述照明光的光通量调整至与所述提高所述图像数据的各像素的灰阶值相适应。所述信号处理器130可以依据所述调整系数k发出代表所述调整系数k的光通量调整信号至所述发光装置的驱动部件，所述发光装置110的驱动部件140可以依据所述调整系数k控制所述调节部件150将所述照明光的光通量调整至与所述提高所述图像数据的各像素的灰阶值相适应。具体地，所述发光装置110发出的照明光的标准光通量L0也可以看做所述发光装置110正常发出的照明光的光通量，也即是k＝1时的光通量，换句话说，所述DMD依据所述图像数据的原始灰阶值调制所述标准光通量为L0的照明光获得的投影光刚好可以准确地还原所述图像数据的灰阶。所述发光装置110依据所述调整系数k调整所述照明光的光通量是将所述照明光的光通量调整为原始光通量的1/k，即所述发光装置110发出的 调整后的光通量为标准光通量的1/k，即L0/k。所述DMD的各个反射镜单元接收光通量为L0/k的照明光，并依据调整后的灰阶值kGi调制所述光通量为L0/k的照明光产生投影光，所述投影光的光通量为kGi*L0/k，其与依据原始灰阶值Gi调制原始光通量为L0获得的光通量为Gi*L0是相同的，所述DMD的各个反射镜单元发出的投影光准确还原了所述图像数据的各像素的灰阶值。
当然，在变更实施方式，所述调整系数k也可以依据实际需要来选择，如当所述图像数据的各像素的灰阶值均小于(GMax+1)/2时，所述调整系数k也可以设定为2倍，即k＝2。以一帧图像数据进行举例说明，所述一帧图像数据包括红色子帧图像数据、绿色子帧图像数据及蓝色子帧图像数据，设所述一帧图像数据中，其中一像素的原始红色灰阶值、原始绿色灰阶值及原始蓝色灰阶值分别为(50，60，80)，可以将所述调整系统设定为2倍，由此，所述信号处理器130依据所述调整系数将所述像素的红色灰阶值、绿色灰阶值及蓝色灰阶值均调整至原来的两倍，即(100，120，160)，同时所述照明光的光通量可以被调整至原始照明光的一半，即50％，亦将所述图像数据的灰阶准确还原。
进一步地，如图6所示，所述发光装置110可以包括光源模块111、与光学中继系统112，所述光源模块111发出照明光，所述光学中继系统112用于将所述照明光进行光路改变、匀光等处理后以及将所述处理后的照明光提供至所述DMD。
在一种实施方式中，所述发光装置110可以通过改变所述照明光的光通量，即将所述调节部件150设置于所述光源模块111中，所述调节部件150可以为光源驱动电路，用于调整所述光源模块111的发光元件(如激光器)的驱动电流来改变所述照明光的光通量；然而，在另一种实施方式中，所述发光装置110也可以通过所述光学中继系统112改变所述照明光的发散角(或者说照明光的F数)来调整所述照明光的光通量，即将所述调节部件150设置于所述光学中继系统112中；又或者，在再一种实施方式中，所述发光装置110通过改变所述 光源模块发出的照明光的光通量与在光学中继系统112中改变所述照明光的发散角(或者说照明光的F数)相结合的方式来调整所述照明光的光通量，将分别设置所述调节部件150于所述光源模块111及所述光学中继系统112中。具体地，所述发光装置110可以通过减小所述光学中继系统112提供的照明光的发散角、提高所述光学中继系统112提供的照明光的F数，以及减少所述光学中继系统112提供的照明光的光通量。
本实施方式中，主要以所述发光装置110的光学中继系统112通过改变所述照明光的发散角(或者说照明光的F数)来调整所述照明光的光通量为例进行说明。具体地，设所述发光装置110发出的照明光的光通量为所述标准光通量L0时，所述发光装置110发出的照明光的基准发散角为θ。(其对应的F数为基准F数F。)，当所述图像数据的各像素的灰阶值被提高时，所述发光装置110依据所述调整系数将所述照明光的发散角调整为小于所述基准发散角(或者说将所述照明光的F数调整为大于所述基准F数F。)，且所述调整后的照明光的发散角与所述基准发散角之间的比值与所述调整系数成反比(所述调整后的照明光的F数与所述基准F数F。之间的比值与所述调整系数k成正比)，即，所述调整系数k越大，所述调整后的照明光的发散角与所述基准发散角之间的比值越小(所述调整后的照明光的F数与所述基准F数F。之间的比值越大)，即，所述调整后的照明光的发散角越小(所述调整后的照明光的F数越大)。
换句话说，从F数调整的角度来看，所述发光装置110可以通过改变所述照明光的F数来调整所述照明光的光通量。具体地，设所述发光装置发出的照明光的光通量为所述标准光通量L0时，所述发光装置110发出的照明光的对应的F数为基准F数F。，当所述图像数据的各像素的灰阶值被提高时，所述发光装置110依据所述调整系数将所述照明光的F数调整为大于所述基准F数F。，且所述调整后的照明光的F数与所述基准F数F。之间的比值与所述调整系数k成正比，即，所述调整系数k越大，所述调整后的照明光的发散角与所述基准发散 角之间的比值越小，且所述调整后的照明光的F数与所述基准F数F。之间的比值越大，从而，所述调整后的照明光的发散角越小，且所述调整后的照明光的F数越大。
具体地，所述光学中继系统112中设置有所述调节部件150，所述调节部件150在所述图像数据的各像素的灰阶值被提高时调整所述光学中继系统112发出的所述照明光的发散角(或者说F数)、提高所述光学中继系统提供的照明光的F数，以及减少所述光学中继系统提供的照明光的光通量，使得所述照明光的光通量与所述灰阶值提高后的图像数据相适应，进而所述照明光的光通量与所述灰阶值提高后的图像数据相适应。
可以理解，依据图4的分析可知，照射到所述DMD的反射镜单元102的发散角越大(即F数越小)，所述杂散光区域越大，杂散光对投影系统对比度的影响就越大，本实施方式中，通过将调整后的照明光的发散角减小(即F数增大)，不仅可以减小光通量提高反射镜单元102的“ON”时间(减小“OFF”时间)来减小杂散光，还可以通过减小发散角来减小杂散光区域，进一步提高对比度。
请再次参阅图6，本实施方式中，所述光学中继系统112还包括依序设置的光学系统113、匀光器件114、及中继系统115。
所述光源模块111发出照明光至所述光学系统113。所述光源模块111可以包括发光元件与波长转换元件，所述发光元件用于发出激发光，所述波长转换元件可以为色轮，其上设置有波长转换材料，如荧光材料(红色、黄色、绿色荧光材料等)，所述波长转换元件用于接收所述激发光并将一部分激发光转换为受激光，从而发出包括所述受激光及另一部分激发光作为所述照明光。所述发光元件可以包括激光光源，如蓝色激光光源，所述激发光可以包括激光，如蓝色激光。
所述光学系统113用于对所述光源模块111发出的照明光进行收集等处理并将所述照明光引导至所述匀光器件114。
所述匀光器件114用于将所述光学系统113发出的照明光进行匀光，并将所述匀光后的照明光提供至所述中继系统115。所述匀光器 件114可以包括匀光方棒，所述光学系统113发出的照明光通过所述方棒的入口进入所述方棒，并在所述方棒内壁镜面反射或全内反射将照明光均匀化，再从所述方棒的出口射出匀光后的照明光。可以理解，在变更实施方式中，所述匀光器件114也可以包括复眼透镜。
所述中继系统115用于将所述匀光后的照明光提供至所述DMD。具体地，所述中继系统115主要包括一些中继透镜116，将匀光器件114(方棒或复眼)的照明光按一定的角度提供到DMD表面。本实施方式中，所述调节部件150可以设置于所述中继系统115中。具体地，所述调节部件150为可调光圈，其用于改变所述照明光的发散角、F数与光通量，且所述可调光圈可以设置于所述中继系统115的孔径光阑处，所述可调光圈用于遮挡入射至所述可调光圈的照明光的光束的外围部分，以使得从所述可调光圈出射的照明光相对于入射的照明光的发散角变小、F数提高以及光通量减小。所述驱动部件140可以包括驱动马达，所述驱动马达可以驱动所述可调光圈对所述照明光的发散角、F数与光通量进行控制。进一步地，可以理解，所述发散角减小和F数提高的幅度取决于所需要减小的光通量的幅度，在本实施方式中，取决于所述可调光圈遮挡的所述入射至所述可调光圈的照明光的多少，也就是所述可调光圈的光圈大小，也就是说，需要根据光通量减小的幅度去计算发散角需要减小多少度，从而调节所述可调光圈的光圈大小使得所述可调光圈控制所述发散角达到需要调节的角度。
具体地，所述中继系统115包括中继透镜116，从所述匀光器件114(如方棒)边缘光线的主光轴可以看出，所述匀光器件114发出的边缘光线的主光轴与所述中继系统115的中心轴的相交处即为孔径光阑的位置。具体地，所述调节部件150的可调光圈的中心与所述中继系统115的中心轴重合，且垂直放置。其中所述匀光器件114发出的边缘光线的主光轴的位置可以由所述中继透镜116来界定，如所述匀光器件114上部边缘光线经由所述中继透镜116后刚好入射至所述DMD下部边缘的位置，而所述匀光器件114下部边缘光线经由所述中继透镜116后刚好入射至所述DMD上部边缘的位置，从而使得所述匀 光器件114发出的光斑经由所述中继透镜116刚好成像至所述DMD具有各反射镜的表面上。另外，可以理解，所述调节部件150的可调光圈可能存在实际厚度但对F数的调整影响非常小，可以被忽略，因此，此处不考虑所述可调光圈可能存在实际厚度的影响，只需将所述可调光圈所在的位置与所述孔径光阑的位置有重合就好。
请参阅图7，图7是所述投影系统100的工作时序图。所述投影系统100工作时，所述信号源120提供待显示的图像数据至所述信号处理器130，所述信号处理器130分析所述图像数据，设所述图像数据包括第一子帧图像数据与第二子帧图像数据，其中所述第一子帧图像数据的多个像素的最高灰阶值达到灰阶极大值Gmax(如255灰阶)，即，大于等于所述预设值(如230灰阶)，所述第二子帧图像数据的多个像素的最高灰阶值(如228灰阶)没有达到灰阶极大值Gmax(如255灰阶)且也小于所述预设值(如230灰阶)，即，大于等于所述预设值(如230灰阶)。
在第一子帧调制时间T1，所述信号处理器130依据所述第一子帧图像数据的多个像素的最高灰阶值(如255灰阶)判断所述第一子帧图像数据无需再进行灰阶提高处理，所述信号处理器130在第一时段将所述第一子帧图像数据(即原始的第一子帧图像数据)提供至所述DMD。同时，所述驱动部件140也依据图像数据判断或接收所述信号处理器130输出的信号获知无需进行光通量的调整，所述驱动部件140控制所述调节部件150使得所述照明光的光通量保持所述标准光通量Lo，并即将所述标准光通量Lo的照明光提供至所述DMD。所述DMD依据所述原始的第一子帧图像数据调制所述标准光通量Lo的照明光得到投影光。
在第二子帧调制时间T2，所述信号处理器130依据所述第二子帧图像数据的多个像素的最高灰阶值(如228灰阶，低于所述预设值230灰阶)判断所述第一子帧图像数据需要进行灰阶提高处理，所述信号处理器130依据所述最高灰阶值计算调制系数k，k＝灰阶极大值/最高灰阶值，且将所述第二子帧图像数据的各像素的灰阶值均乘以所述调 制系数k获得提高后的第二子帧图像数据的各像素的灰阶值，并将所述灰阶提高后的第二子帧图像数据提供至所述DMD。同时，所述驱动部件140也依据图像数据判断或接收所述信号处理器130输出的信号获知需要进行光通量的调整，所述驱动部件140控制所述调节部件150使得所述照明光的光通量调整为所述标准光通量Lo的1/k，并即将仅为所述标准光通量Lo的1/k的光通量的照明光提供至所述DMD。所述DMD依据所述灰阶提高后的第二子帧图像数据调制所述Lo/k的光通量的照明光得到投影光。
依据上述分析可知，所述信号处理器130将所述图像数据的多个像素的灰阶值提高，所述发光装置110将所述照明光的光通量降低，所述DMD依据所述提高了灰阶值的图像数据调制所述光通量降低的照明光产生投影光，所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应，不仅可以准确还原了所述图像数据的多个像素的原始灰阶值，还由于所述灰阶值的提高导致所述DMD每个反射镜的“ON”时间提高，而“OFF”时间减小，从而减少“OFF”时间产生的杂散光，减少杂散光对投影系统100对比度的影响，使得所述投影系统100的对比度提高。
请参阅图8，图8是本发明提供的第二实施方式的可提高图像对比度的投影系统200的结构示意图。所述第二实施方式的投影系统200与第一实施方式的投影系统100基本相同，也就是说，上述针对所述第一实施方式的投影系统100的描述基本上可以适用于第二实施方式的投影系统200，二者的区别主要在于：所述第二实施方式中，调节部件250设置于光学系统223中，且所述调节部件250为液晶透镜，驱动部件240通过液晶透镜控制所述照明光的发散角、F数以及光通量。可以理解，所述液晶透镜可以是所述光学系统的最后一片透镜，所述驱动部件240可以通过驱动电压的改变控制所述液晶透镜中液晶的排布，使得所述液晶透镜的折射率发生改变，进而所述液晶透镜的焦距也随着改变，从而使得所述照明光的发散角、F数以及光通量改变。
本实施方式中，当所述发光装置210的光通量被调整为小于标准光通量Lo时，入射至匀光器件214的入射面位置的照明光的光束的横截面的面积大于所述匀光器件214的入射面的面积，即通过所述调节部件250调整所述入射至所述匀光器件214的入射面位置的照明光光束的横截面的面积，使得所述照明光光束的横截面的面积大于所述匀光器件214的入射面的面积，来达到将所述照明光的光通量调整为小于所述标准光通量。进一步地，可以理解，所述发散角减小和F数提高的幅度取决于所需要减小的光通量的幅度，也就是说，需要根据光通量减小的幅度去计算发散角需要减小多少度，从而使得光束的横截面面积超出所述匀光器件214的入射面的面积。
需要说明的是，所述调节前后的液晶透镜的焦距都是大于液晶透镜与匀光部件114的入射面的距离的。因为，若是小于的话，调小照明光的发散角并不能使得入射至匀光部件114的入射面的光束的横截面增大，如图9所示，若液晶透镜的焦距小于液晶透镜与匀光部件114的距离，则照明光的发散角调小后，其入射至匀光器件114入射面的光斑的横截面反而更小了。
请参阅图9，图9是本发明投影方法的流程图，本发明投影方法可以用于上述第一及第二实施方式的投影系统100与200。具体地，所述投影方法可以包括如下步骤S1、S2、S3、S4及S5。
步骤S1，接收图像数据，其中所述图像数据包括多个灰阶值，其中每个灰阶值对应一个像素。具体地，如图6所示，所述步骤S1可以由所述信号处理器130执行，即所述信号处理器130可以接收所述信号源120发出的图像数据。
步骤S2，将所述图像数据的多个像素的灰阶值提高。
具体地，所述步骤S2中，可以对所述图像数据的各像素的灰阶值进行分析，当所述图像数据的各像素的最高灰阶值小于预设值时，将所述图像数据的各像素的灰阶值提高。具体地，所述步骤S2可以由所述信号处理器130执行，即，所述信号处理器130接收所述信号源120发出的图像数据，并分析所述图像数据的各像素的最高灰阶值，当所 述图像数据的各像素的最高灰阶值小于所述预设值时，所述信号处理器130将所述图像数据的各像素的灰阶值提高。具体地，所述图像数据可以为一子帧图像数据，其中所述子帧图像数据可以为红色子帧图像数据、绿色子帧图像数据或蓝色子帧图像数据，所述信号处理器130可以在所述子帧图像数据中的各像素中的最高灰阶值低于所述预设值时，将所述子帧图像数据的各像素的灰阶值提高、以及将灰阶值提高后的子帧图像数据提供至所述DMD。
具体地，设使用所述投影方法的所述投影系统100、200可以显示的灰阶范围为0至GMax，如0至(2m-1)灰阶，其中，m可以为8，所述灰阶范围可以为0至255灰阶，GMax代表所述投影系统100、200可以显示的灰阶极大值。所述信号处理器130可以分析所述图像数据的各像素中的最高灰阶值GL，其中可以理解，所述最高灰阶值一般小于等于所述灰阶极大值GMax，并将所述最高灰阶值GL与所述预设值GR进行比较，其中，所述预设值GR也可以小于等于所述灰阶极大值GMax，如所述预设值为所述灰阶极大值Gmax的90％，即，当所述灰阶极大值为255灰阶时，所述预设值可以为230灰阶。当所述最高灰阶值GL小于所述预设值GR时，所述步骤S2还可以具体包括如下步骤：计算调整系数，以及依据所述调整系数提高所述图像数据的各像素的灰阶值，并将灰阶值提高后的图像数据提供到所述DMD。具体地，所述调整系数k可以等于所述极大灰阶值GMax/所述最高灰阶值GL，由于所述图像数据的最高灰阶值GL一般小于极大灰阶值GMax，因此所述k大于等于1，所述信号处理器130控制将所述图像数据的各像素的灰阶值均调整至k倍，设所述图像数据中的任意一像素的原始灰阶值为Gi，则调整后的所述像素的灰阶值为kGi。
当然，在变更实施方式，所述调整系数k也可以依据实际需要来选择，如当所述图像数据的各像素的灰阶值均小于(GMax+1)/2时，所述调整系数k也可以设定为2倍，即k＝2。以一帧图像数据进行举例说明，所述一帧图像数据包括红色子帧图像数据、绿色子帧图像数据及蓝色子帧图像数据，设所述一帧图像数据中，其中一像素的原始 红色灰阶值、原始绿色灰阶值及原始蓝色灰阶值分别为(50，60，80)，可以将所述调整系统设定为2倍，由此，所述信号处理器130依据所述调整系数将所述像素的红色灰阶值、绿色灰阶值及蓝色灰阶值均调整至原来的两倍，即(100，120，160)，同时所述照明光的光通量可以被调整至原始照明光的一半，即50％，亦将所述图像数据的灰阶准确还原。
步骤S3，提供照明光，将所述照明光的光通量调小，其中所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应。具体地，所述步骤S3可以由所述发光装置执行。
步骤S4，依据所述灰阶值提高后的图像数据调制所述调小后的光通量的照明光产生投影图像所需要的投影光。具体地，所述步骤S3可以由所述DMD执行。
具体地，所述步骤S3可以包括如下步骤：在所述图像数据的各像素中的最高灰阶值低于预设值时将所述照明光的光通量调整为小于所述标准光通量，使得所述调整后照明光的光通量与所述灰阶值提高后的图像数据相适应。具体地，所述发光装置110可以包括驱动部件140与调节部件150，其中所述驱动部件140控制所述调节部件150对所述发光装置110发出的照明光进行光通量调整。
在一种实施方式中，所述发光装置110的驱动部件140可以直接分析图像数据从而依据图像数据判断所述信号处理器130是否会将所述图像数据的各像素的灰阶值提高，若所述发光装置110的驱动部件140依据所述图像数据判断所述信号处理器130会将所述图像数据的各像素的灰阶值提高，则所述发光装置110的驱动部件140控制所述调节部件150对应调小所述照明光的光通量，具体地，所述发光装置110的驱动部件140可以分析所述图像数据的各像素中的最高灰阶值是否低于所述预设值，当所述图像数据的各像素中的最高灰阶值低于所述预设值，所述发光装置110的驱动部件140控制所述调节部件150对应调小所述照明光的光通量。
在另一种实施方式中，所述发光装置110的驱动部件140可以接 收所述信号处理器130在调高所述图像数据的各像素的灰阶值时发出的光通量调整控制信号，进而所述发光装置110的驱动部件140可以依据所述信号处理器130发出的光通量调整信号控制所述调节部件150对应调小所述照明光的光通量。具体地，所述信号处理器130可以分析所述图像数据的各像素中的最高灰阶值是否低于所述预设值，当所述图像数据的各像素中的最高灰阶值低于所述预设值时，所述信号处理器130将所述图像数据的多个像素的灰阶值提高、以及将灰阶值提高后的图像数据提供至所述DMD，同时还发送所述光通量调整信号至所述发光装置的驱动部件，使得所述发光装置110的驱动部件140依据所述光通量调整信号控制所述调节部件对应调小所述照明光的光通量。具体地，所述发光装置110的驱动部件140可以依据所述调整系数k控制所述调节部件150将所述照明光的光通量调整至与所述提高所述图像数据的各像素的灰阶值相适应。所述信号处理器130可以依据所述调整系数k发出代表所述调整系数k的光通量调整信号至所述发光装置110的驱动部件140，所述发光装置110的驱动部件140可以依据所述调整系数k控制所述调节部件150将所述照明光的光通量调整至与所述提高所述图像数据的各像素的灰阶值相适应。
更进一步地，在一种实施方式中，如图7所示，所述调节部件150可以为设置于所述发光装置110的中继系统115中的可调光圈，其用于改变所述照明光的发散角(或者说所述照明光的F数)，且所述可调光圈可以设置于所述中继系统115的孔径光阑处，所述可调光圈用于遮挡入射至所述可调光圈的照明光的光束的外围部分，以使得从所述可调光圈出射的照明光相对于入射的照明光的发散角变小、F数提高以及光通量减小。所述驱动部件140可以包括驱动马达，所述驱动马达可以驱动所述可调光圈对所述照明光的发散角进行控制。进一步地，可以理解，所述发散角减小和F数提高的幅度取决于所需要减小的光通量的幅度，在本实施方式中，取决于所述可调光圈遮挡的所述入射至所述可调光圈的照明光的多少，也就是所述可调光圈的光圈大小，也就是说，需要根据光通量减小的幅度去计算发散角需要减小多少度， 从而调节所述可调光圈的光圈大小使得所述可调光圈控制所述发散角达到需要调节的角度。
具体地，所述中继系统115包括中继透镜116，从所述匀光器件114(如方棒)边缘光线的主光轴可以看出，所述匀光器件114发出的边缘光线的主光轴与所述中继系统115的中心轴的相交处即为孔径光阑的位置。具体地，所述可调光圈的中心与所述中继系统115的中心轴重合，且垂直放置。其中所述匀光器件114发出的边缘光线的主光轴的位置可以由所述中继透镜116来界定，如所述匀光器件114上部边缘光线经由所述中继透镜116后刚好入射至所述DMD下部边缘的位置，而所述匀光器件114下部边缘光线经由所述中继透镜116后刚好入射至所述DMD上部边缘的位置，从而使得所述匀光器件发出的光斑经由所述中继透镜116刚好成像至所述DMD具有各反射镜的表面上。另外，可以理解，所述可调光圈可能存在实际厚度但对F数的调整影响非常小，可以被忽略，因此，此处不考虑所述可调光圈可能存在实际厚度的影响，只需将所述可调光圈所在的位置与所述孔径光阑的位置有重合就好。
在另一种实施方式中，如图8所示，所述调节部件150可以设置于所述光学系统113中，且所述调节部件150为液晶透镜，所述驱动部件140通过液晶透镜控制所述照明光的发散角、F数与光通量。可以理解，所述液晶透镜可以是所述光学系统的最后一片透镜，所述驱动部件140可以通过驱动电压的改变控制所述液晶透镜中液晶的排布，使得所述液晶透镜的折射率发生改变，进而所述液晶透镜的焦距也随着改变，从而使得所述照明光的发散角、F数与光通量改变。
本实施方式中，当所述发光装置210的光通量被调整为小于标准光通量Lo时，入射至匀光器件214的入射面位置的照明光的光束的横截面的面积大于所述匀光器件214的入射面的面积，即通过所述调节部件250调整所述入射至所述匀光器件214的入射面位置的照明光光束的横截面的面积，使得所述照明光光束的横截面的面积大于所述匀光器件214的入射面的面积，来达到将所述照明光的光通量调整为小 于所述标准光通量。进一步地，可以理解，所述发散角减小和F数提高的幅度取决于所需要减小的光通量的幅度，也就是说，需要根据光通量减小的幅度去计算发散角需要减小多少度，从而使得光束的横截面面积超出所述匀光器件214的入射面的面积。
需要说明的是，所述调节前后的液晶透镜的焦距都是大于液晶透镜与匀光部件114的入射面的距离的。因为，若是小于的话，调小照明光的发散角并不能使得入射至匀光部件114的入射面的光束的横截面增大，如图10所示，若液晶透镜的焦距小于液晶透镜与匀光部件114的距离，则照明光的发散角调小后，其入射至匀光器件114入射面的光斑的横截面反而更小了。
具体地，所述发光装置110发出的照明光的标准光通量为L0也可以看做所述发光装置110正常发出的照明光的光通量，也即是k＝1时的光通量，换句话说，所述DMD依据所述图像数据的原始灰阶值调制所述标准光通量为L0的照明光获得的投影光刚好可以准确地还原所述图像数据的灰阶。所述发光装置110依据所述调整系数k调整所述照明光的光通量是将所述照明光的光通量调整为原始光通量的1/k，即所述发光装置发出的调整后的光通量为标准光通量的1/k，即L0/k。所述DMD的各个反射镜单元接收光通量为L0/k的照明光，并依据调整后的灰阶值kGi调制所述光通量为L0/k的照明光产生投影光，所述投影光的光通量为kGi*L0/k，其与依据原始灰阶值Gi调制原始光通量为L0获得的光通量为Gi*L0是相同的，所述DMD的各个反射镜单元102发出的投影光准确还原了所述图像数据的各像素的灰阶值。
步骤S5，依据所述投影光产生投影图像，其中所述投影光的亮度与所述灰阶值提高前的图像数据相匹配。
所述步骤S5可以通过投影镜头实现，所述投影镜头可以接收所述DMD发出的投影光并将所述投影光投影在投影屏幕上进行投影图像的显示，由于所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应，因此所述投影光的亮度与所述灰阶值提高前的图像数据相匹配。
以上所述仅为本发明的实施例，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他相关的技术领域，均同理包括在本发明的专利保护范围内。

Claims (14)

  1. 一种投影系统，其特征在于：所述投影系统包括
    信号处理器，用于接收图像数据，所述图像数据包括多个灰阶值，其中每个灰阶值对应一个像素，所述信号处理器还用于将所述图像数据的多个像素的灰阶值提高；
    光源，用于发出照明光，
    光学中继系统，用于将所述照明光提供给DMD以使得DMD调制得到投影图像所需要的投影光；
    调节部件，用于在所述图像数据的多个像素的灰阶值被提高时将提供至所述DMD的照明光的光通量调小，所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应；及
    DMD，用于依据所述灰阶值提高后的图像数据调制所述调整后的照明光，以产生投影图像所需要的投影光；
    所述投影光的亮度与所述灰阶值提高前的图像数据相匹配。
  2. 如权利要求1所述的投影系统，其特征在于：所述信号处理器接收所述图像数据，所述图像数据包括一子帧图像数据，所述信号处理判断所述子帧图像数据中各像素的最高灰阶值是否小于预设值，当所述子帧图像数据中各像素的最高灰阶值小于所述预设值，所述信号处理器控制将所述子帧图像数据的各像素的灰阶值提高，所述发光装置在所述子帧图像数据中各像素的最高灰阶值小于所述预设值时将所述照明光的光通量调整为小于标准光通量Lo；当所述子帧图像数据中各像素的最高灰阶值大于或等于所述预设值，所述信号处理器将所述子帧图像数据的各像素的灰阶值保持不变并将所述子帧图像数据提供至所述DMD，所述发光装置发出所述标准光通量Lo的照明光，所述DMD依据所述灰阶值不变的子帧图像数据调制所述标准光通量Lo的照明光产生投影图像所需要的投影光。
  3. 如权利要求2所述的投影系统，其特征在于：设所述投影系统可达到的灰阶极大值为Gmax，设所述预设值为GR，所述预设值GR小于等于所述灰阶极大值Gmax。
  4. 如权利要求3所述的投影系统，其特征在于：所述预设值为所述灰阶极大值Gmax的90％。
  5. 如权利要求3所述的投影系统，其特征在于：所述信号处理器还在所述子帧图像数据中各像素的最高灰阶值小于所述预设值时计算调整系数k，其中所述调整系数k等于Gmax/GL，GL代表所述子帧图像数据中各像素的最高灰阶值，所述信号处理器依据所述调整系数k将所述图像数据的各像素的灰阶值均调整至所述图像数据的各像素的灰阶值的k倍，所述发光装置发出的照明光的光通量则被调整为标准光通量Lo的1/k。
  6. 如权利要求1所述的投影系统，其特征在于，所述调节部件用于调整所述光源发出的照明光的光通量。
  7. 如权利要求1所述的投影系统，其特征在于，所述调节部件用于减小所述光学中继系统提供的照明光的发散角、提高所述光学中继系统提供的照明光的F数，以及减少所述光学中继系统提供的照明光的光通量。
  8. 如权利要求7所述的投影系统，其特征在于，所述调节部件包括可调光圈，所述可调光圈设置于所述光学中继系统的孔径光阑处；所述可调光圈用于遮挡入射至所述可调光圈的照明光的光束的外围部分，以使得从所述可调光圈出射的照明光相对于入射至所述可调光圈的照明光的发散角变小、F数提高以及光通量减小。
  9. 如权利要求7所述的投影系统，其特征在于，所述光学中继系统包括匀光部件，用于对所述照明光进行匀光；
    所述调节部件包括液晶透镜，所述液晶透镜位于所述匀光部件之前光路上，从所述液晶透镜出射的光照射至匀光部件的入射面；
    所述液晶透镜用于调小所述照明光的发散角，使得所述照明光束在投射至所述匀光部件的入射面位置时横截面的面积大于所述入射面的面积，以使得进入所述匀光部件的照明光的发散角减小、F数提高以及光通量减小。
  10. 一种投影方法，其包括如下步骤：
    接收图像数据，其中所述图像数据包括多个灰阶值，其中每个灰阶值对应一个像素，；
    将所述图像数据的多个像素的灰阶值提高；
    提供照明光，将所述照明光的光通量调小，其中所述照明光的光通量调小的比例与所述图像数据的灰阶值提高的比例相适应；
    依据所述灰阶值提高后的图像数据调制所述调小后的光通量的照明光产生投影图像所需要的投影光；及
    依据所述投影光产生投影图像，其中所述投影光的亮度与所述灰阶值提高前的图像数据相匹配。
  11. 如权利要求10所述的投影方法，其特征在于：
    当所述图像数据中各像素的最高灰阶值小于预设值，则将所述图像数据的各像素的灰阶值提高；
    当所述子帧图像数据中各像素的最高灰阶值大于或等于所述预设值，将所述子帧图像数据的各像素的灰阶值保持不变，控制所述照明光的光通量为标准光通量Lo，依据所述灰阶值不变的图像数据调制所述标准光通量Lo的照明光产生投影图像所需要的投影光。
  12. 如权利要求11所述的投影方法，其特征在于：设使用所述方法的投影系统可达到的灰阶极大值为Gmax，设所述预设值为GR，所述预设值GR小于等于所述灰阶极大值Gmax。
  13. 如权利要求12所述的投影方法，其特征在于：所述预设值为所述灰阶极大值Gmax的90％。
  14. 如权利要求12所述的投影方法，其特征在于：
    在所述子帧图像数据中各像素的最高灰阶值小于所述预设值时计算调整系数k，其中所述调整系数k等于Gmax/GL，GL代表所述子帧图像数据中各像素的最高灰阶值，
    依据所述调整系数k将所述图像数据的各像素的灰阶值均调整至所述图像数据的各像素的灰阶值的k倍，即设所述图像数据的任意一像素的灰阶值为Gi，则所述图像数据的像素的灰阶值Gi对应的提高后的灰阶值为k*Gi，所述照明光的光通量则被调整为所述标准光通量 Lo的1/k，即所述照明光的光通量为Lo/k。
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