CN107797368A - Double space light modulation system and the method that light regulation is carried out using the system - Google Patents

Abstract

The present invention proposes a dual spatial light modulation system, including a light source for providing source light to the system; a first spatial light modulator for modulating the light emitted by the light source to form a first light and second light not used to display images; a second spatial light modulator, configured to receive the first light and the second light, and modulate the first light and the second light; The processing device is used to perform subsequent processing on the light modulated by the second spatial light modulator; the light recycling device is used to transmit the second light to the second spatial light modulator, which is located in the first between the spatial light modulator and the second spatial light modulator. The present invention also provides a light adjustment method. By using the dual-space light modulation system and the light adjustment method using the system of the present invention, the brightness and contrast of the system can be freely adjusted to achieve a balance between the system brightness and contrast.

Description

Dual spatial light modulation system and method for light regulation using the system

technical field

The invention belongs to the field of optical technology, and in particular relates to a dual-space light modulation system and a light adjustment method.

Background technique

At present, projection technology is widely used in people's daily life. The use of projection systems can be seen everywhere in conferences, teaching or entertainment venues. Improving the dynamic range (HDR) of the projection system is one of the main directions for the next development of the projection system.

To increase the dynamic range of projection systems, it is a common practice to use dual spatial light modulators. As shown in Figure 1, 1' is the No. 1 light source, 2' is the No. 1 spatial light modulator, 3' is the No. 2 spatial light modulator, and 4' is the auxiliary structure, which is the projection system in the No. 2 spatial light modulator 3 'After the part, it can include the relay mirror group, the lens and the screen, etc. The light source 1' emits light source light, and the image light formed by modulating the light source light by the first spatial light modulator 2' is projected onto the second spatial light modulator 3', and the second spatial light modulator 3' further modulates the image light. The spatial light modulator includes a plurality of modulation units, and one modulation unit is used to modulate the image light of one pixel. The resolution of the image finally modulated by the system is determined by the resolution of the image modulated by the No. 2 spatial light modulator 3'; generally, the resolution of the image modulated by the No. 1 spatial light modulator 2' is less than or equal to that of the No. 2 spatial light modulator the resolution of the image modulated by the first spatial light modulator 2', the image light of one pixel modulated by the first spatial light modulator 2' is projected onto the multiple modulation units of the second spatial light modulator 3', and the multiple modulation units The image light forming a plurality of pixels is further modulated; thus, one pixel modulated by the first spatial light modulator 2' corresponds to one or more pixels modulated by the second spatial light modulator 3'.

The contrast ratio of the spatial light modulator can be understood as: the spatial light modulator modulates the incident light uniformly incident on each modulation unit, the brightness ratio of the image light of all white pixels and the image light of all black pixels formed, the brightness The ratio is equal to the ratio of the conversion efficiency corresponding to all white pixels to the conversion efficiency corresponding to all black pixels; the so-called conversion efficiency corresponding to all white pixels is: the image light of all white pixels formed by spatial light modulation and the light incident on the spatial light modulator The luminance ratio of incident light; and the conversion efficiency corresponding to the so-called all-black pixel is: the luminance ratio of the image light of the all-black pixel formed by spatial light modulation to the incident light incident on the spatial light modulator. The light extraction efficiency of the spatial light modulator can be considered as the conversion efficiency corresponding to all white pixels.

The contrast ratio of No. 1 spatial light modulator 2' is a: 1 (a>1) and the light extraction efficiency is c (0<c≤1), and the contrast ratio of No. 2 spatial light modulator 3' is b: 1 (b >1) and the light extraction efficiency is d (0≤d≤1) as an example. Assuming that the light source light is uniformly incident on the No. 1 spatial light modulator 2', and the brightness of the light source light incident on the No. 1 spatial light modulator 2' is set to 1; The brightness of the image light WL of a pixel is 1*c, and the brightness of the image light BL of a completely black pixel modulated by the first spatial light modulator 2 ′ is 1*c/a. Assuming that the No. 2 spatial light modulator 3' further modulates the image light WL to form an all-white pixel, then the brightness of the modulated image light of the all-white pixel is 1*c*d; and the No. 2 spatial light modulator 3' further converts The image light BL is modulated to form all black pixels, and the brightness of the image light of the modulated all black pixels is (1*c/a)*d/b. The final contrast of the projection system can be regarded as the brightness ratio of the image light of all white pixels and the image light of all black pixels formed by the second spatial light modulator 3', which is a*b:1; the final light output efficiency of the projection system It can be considered as the brightness ratio of the image light of the all-white pixel formed by the second spatial light modulator 3 ′ to the light source light, namely c*d.

It can be seen that, by using two spatial light modulators, the contrast ratio of the system can be greatly improved, however, the light extraction efficiency of the system is relatively reduced.

Contents of the invention

In view of the above shortcomings of the prior art, the present invention proposes a dual-spatial light modulation system. By using the dual-spatial light modulation system of the present invention, a balance is achieved between light extraction efficiency and contrast.

The present invention provides a dual spatial light modulation system, comprising a light source, a first spatial light modulator, a second spatial light modulator and a light recycling device, the light source is used to provide source light; the first spatial light modulator is used to for modulating the source light to form the first light for displaying images emitted along the first path and the second light not used for displaying images emitted along the second path; the light recovery device is used for receiving the second light emitted by two paths, guide the second light to combine with the first light, and transmit the combined light of the first light and the second light to the second space light modulator; the second spatial light modulator is used to receive the combined light of the first light and the second light, and modulate the combined light of the first light and the second light to form Image light for projection onto the screen.

Preferably, the light recovery device includes: an optical path conversion component, configured to receive the second light emitted along the second path, and change the optical path of the second light, so that the second light is transmitted to the light combination device and the light combining device, configured to receive the second light transmitted by the optical path conversion component, and receive the first light, and combine the received second light with the first light.

Preferably, the optical path conversion component includes: a first reflector, configured to receive the second light emitted along the second path, and reflect the second light; a second reflector, configured to receive the first light The second light reflected by the mirror further reflects the second light to the light combination device.

Preferably, the light recovery device further includes: a light homogenization device, used to homogenize the second light before the second light is transmitted to the light combining device.

Preferably, the light recovery device further includes: a controllable attenuation device, configured to attenuate the second light according to a specified attenuation parameter before the second light is transmitted to the light combining device.

Preferably, the source light includes red light, green light and blue light provided to the first spatial light modulator in time sequence within a frame color image modulation period; the first spatial light modulator according to a color frame image The red, green and blue monochromatic frame image data contained in the data modulate the red light, green light and blue light respectively; the controllable attenuation device modulates the red light respectively for the first spatial light modulator The second light formed by , green, and blue light is attenuated to obtain second attenuated red light, second attenuated green light, and second attenuated blue light, so that the second attenuated light obtained within one frame of color image modulation period The light quantities of the attenuated red light, the second attenuated green light and the second attenuated blue light are consistent.

Preferably, the dual spatial light modulation system includes three sets of modulation devices, each set of modulation devices includes the first spatial light modulator, light recycling device and the second spatial light modulator; the source light Including red light, green light and blue light respectively provided to the three sets of modulation devices within a frame color image modulation period; the first spatial light modulators in the three sets of modulation devices are respectively based on a color frame image The red, green and blue monochromatic frame image data contained in the data modulate the red light, green light and blue light; the controllable attenuation devices in the three modulation devices respectively control the corresponding first space The second light formed by the red light, green light and blue light modulated by the light modulator is attenuated to obtain the second attenuated red light, the second attenuated green light and the second attenuated blue light, so that within a frame of color image modulation period, The light quantities of the second attenuated red light, the second attenuated green light and the second attenuated blue light are consistent.

Preferably, the control device is used to calculate the recyclable light ratios corresponding to the red, green and blue monochrome frames contained in each color image data, and control the controllable attenuation device according to the lowest recyclable light ratio among them. Attenuation processing, so that the light quantities of the second attenuated red light, the second attenuated green light and the second attenuated blue light obtained within a frame of color image modulation period are consistent.

Preferably, the first spatial light modulator is LCD or LCOS.

Preferably, the light combining device is a polarization light combining device, the first light transmitted to the light combining device has a first polarization state, and the second light transmitted to the light combining device has a second polarization state, the light combination device is used to combine the first light with the first polarization state and the second light with the second polarization state.

Preferably, the first spatial light modulator is a DMD.

Preferably, the light combination device is a mirror with a through hole; the first light is incident on the second spatial light modulator through the through hole, and the second light is reflected by the mirror to The second spatial light modulator, or the second light is incident on the second spatial light modulator through the through hole, and the second light is reflected by the reflector to the second spatial light modulator Modulator.

Preferably, the first reflector is a plane reflector; or the first reflector is a curved reflector; The second light spot projected by the two lights to the second spatial light modulator has an overlapping area.

Preferably, the second reflector is a plane reflector; or the second reflector is a curved reflector.

Preferably, the controllable attenuation device is a whole controllable liquid crystal panel.

Preferably, the angle between the first reflector and the second reflector is 90°

The present invention also provides a method for light adjustment using the above-mentioned dual spatial light modulation system, including the following steps:

providing source light through which source light is emitted;

source light modulation, the source light is modulated by the first spatial light modulator to form the first light for displaying images emitted along the first path and the second light not used for displaying images emitted along the second path Light;

Combining light, receiving the second light emitted along the second path through the light recycling device, guiding the second light to combine with the first light, and combining the first light with the first light The combined light of the two lights is transmitted to the second spatial light modulator;

For a light display, the combined light synthesized by the first light and the second light is received and modulated by the second spatial light modulator to form image light and projected to a screen for display.

Compared with related technologies, in the dual-spatial light modulation system and the light adjustment method using the system of the present invention, the light recycling device is added, and the second light emitted along the second path is received by the light recycling device. light, and guide the second light to combine with the first light, and transmit the combined light of the first light and the second light to the second spatial light modulator; further through the The second spatial light modulator receives the combined light of the first light and the second light, and modulates the combined light of the first light and the second light to form an image for projection onto a screen Compared with the dual spatial light modulation system without light recycling, the dual spatial light modulation system can reduce the contrast and improve the light extraction efficiency; thus a balance can be achieved between the contrast ratio and the light extraction efficiency.

Description of drawings

The present invention will be described in detail below in conjunction with the accompanying drawings. The content of the above or other aspects of the present invention will become clearer and easier to understand through the detailed description in conjunction with the following drawings. In the attached picture:

Fig. 1 is a schematic structural diagram of a dual spatial light modulator in the prior art.

Fig. 2 is a schematic structural diagram of an embodiment of the dual spatial light modulation system of the present invention.

Fig. 3 is a schematic structural diagram of another embodiment of the dual spatial light modulation system of the present invention.

Figure 4 is an image diagram of the projection display.

Fig. 5 is a schematic diagram of the first light spot and the second light spot projected by the first light and the second light onto the second spatial light modulator.

Each sign in the attached drawing represents as follows:

1: Light source, 1': No. 1 light source;

2: the first spatial light processor, 2': the second spatial light processor;

3: the second spatial light processor, 3': the third spatial light processor;

4: post-processing device, 4': auxiliary structure;

5: the first reflector;

6: Uniform light device;

7: second reflector;

8: Combined light device;

9: Controllable attenuation device.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

The specific implementations/examples described here are specific specific implementations of the present invention, and are used to illustrate the concept of the present invention. limit. In addition to the embodiments described here, those skilled in the art can also adopt other obvious technical solutions based on the claims of the application and the contents disclosed in the description, and these technical solutions include adopting any obvious changes made to the embodiments described here. The replacement and modified technical solutions are all within the protection scope of the present invention.

The first part of the embodiment: Please refer to FIG. 2, which is a schematic structural diagram of an embodiment of the dual spatial light modulation system of the present invention. The present invention proposes a dual spatial light modulation system, which includes a light source 1, a first spatial light modulator 2, a second spatial light modulator 3, a post-processing device 4, a first reflector 5, a uniform light device 6, a second Two reflecting mirrors 7 and a light combining device 8 . The first reflector 5 , uniform light device 6 , second reflector 7 and light combining device 8 form a light recycling device.

Wherein, the light source 1 can be an LED or a laser diode, and is used to provide source light for the dual spatial light modulation system.

The first spatial light modulator 2 is used for modulating the source light emitted by the light source 1 to form a first light for displaying an image emitted along a first path and a second light not used for displaying an image emitted along a second path.

In this embodiment, the first spatial light modulator 2 is LCD or LCOS. Of course, the first spatial light modulator 2 is not limited thereto, and components with the same principle and structure that can meet the image modulation requirements are all feasible. When the first spatial light modulator 2 is an LCD or LCOS, it includes a polarization converter (not shown) and an analyzer (not shown). The polarization converter includes a plurality of polarization conversion units, and each polarization conversion unit corresponds to a pixel in the image. The polarization conversion unit converts a corresponding proportion of the light into light of the first polarization state according to the grayscale value of the pixel, and converts the remaining part into light of the second polarization state. For example, if the grayscale value of a certain pixel is 100, the corresponding polarization conversion unit converts 100/255 of the beam incident on itself into a P polarization state, and 155/255 into an S polarization state. The analyzer has the characteristic of transmitting light of P polarization state and reflecting light of S polarization state.

LCD is the abbreviation of Liquid Crystal Display (liquid crystal display). The structure of LCD is to place liquid crystals in two parallel glasses. There are many small vertical and horizontal wires in the middle of the two glasses. The rod shape is controlled by energizing or not. The crystal molecules change direction and refract light to create the picture.

LCOS is the abbreviation of Liquid Crystal on Silicon, that is, liquid crystal attached to silicon, also known as liquid crystal on silicon, which is a matrix liquid crystal display device based on reflection mode and very small in size.

The second spatial light modulator 3 is used to receive the combined light of the first light and the second light, and modulate the combined light of the first light and the second light to form a Screen image light.

The first light for displaying images formed after being modulated by the first spatial light modulator 2, and the second spatial light modulator 3 is located on the optical path of the first light. The specific type or model of the second spatial light modulator 3 is not limited to the first spatial light modulator 2, and the second spatial light modulator may be LCD, LOS, or DMD.

The post-processing device 4 includes a relay lens group (not shown), a lens (not shown), and the like. The post-processing device 4 is used to perform post-processing such as collecting, diffusing, dodging and shaping the light modulated by the second spatial light modulator 3, and project it onto the screen.

The light recycling device is used to receive the second light emitted along the second path, guide the second light to combine with the first light, and combine the first light with the second light The combined light is transmitted to the second spatial light modulator 3 .

The first reflector 5 is used to receive the second light emitted along the second path and reflect the second light. In this embodiment, the first reflector 5 is a plane reflector or a curved reflector, which can be set according to actual needs.

The light homogenizing device 6 is used for homogenizing the second light before the second light is transmitted to the light combining device 8 .

The second reflector 7 is used to receive the second light reflected by the first reflector 5 , and further reflect the second light to the light combining device 8 . In this embodiment, the second reflector 7 is a plane reflector or a curved reflector, which can be set according to actual needs.

The light combining device 8 is used to receive the second light transmitted by the optical path conversion component, receive the first light, and combine the received second light with the first light.

Specifically, the light combination device 8 is a polarization light combination device, the first light transmitted to the light combination device 8 has a first polarization state, the second light transmitted to the light combination device 8 has a second polarization state, and the light combination device 8 has a second polarization state. The optical device 8 is used for combining the first light with the first polarization state and the second light with the second polarization state. The light combination device 8 transmits the first light with the first polarization state and reflects the second light with the second polarization state.

Further, the spatial angle between the first reflector 5 and the second reflector 7 can be set to 90°. Such an included angle setting can ensure that the second light not used for displaying images can be completely reflected to the second spatial light modulator 3 , thereby ensuring the brightness of the source light. But the present invention is not limited thereto.

In this embodiment, the first reflector 5 and the second reflector 7 form an optical path conversion component to receive the second light emitted along the second path, and change the optical path of the second light so that the second light The light is transmitted to the light combining device 8 .

The present invention does not limit the quantity and type of optical elements included in the optical path conversion component for changing the optical path. For example, the optical path conversion component may include one or both of a reflective mirror capable of changing the optical path and a transmissive mirror capable of changing the optical path, and the number of included optical elements may be multiple. All optical path conversion components used to receive the second light emitted along the second path, and change the optical path of the second light so that the second light is transmitted to the light combination device 8 belong to the protection of the present invention scope.

Of course, in one embodiment, the light combination device 8 can also be a reflector with a through hole, please refer to FIG. 5 : the first light passes through the through hole and enters the second spatial light modulation 3, the second light is reflected to the second spatial light modulator 3 through the light combining device 8; the first light spot projected on the second spatial light modulator 3 by the first light The second light spot projected by the second light onto the second spatial light modulator 3 has an overlapping area. Wherein, the second reflection mirror 7 is a curved surface reflection mirror, and its convex surface reflects the second light. The mirror 7 has a function of diffusing the second light. The light combination device 8 is also a curved reflector, and the second light reflected by the concave surface of the light combination device 8 can be converged into a smaller spot (relative to the second light being projected to the light combination device) through the second light reflected by the light combination device. 8), the light-combining device 8 has a converging effect on the second light.

Or, in another embodiment, the second light is incident to the second spatial light modulator 3 through the through hole of the light combining device 8, and the second light is reflected by the light combining device 8 to the second spatial light modulator 3 . Wherein, the characteristics of the second reflector 7 and the light combination device 8 can be set according to actual needs.

In this embodiment, the first reflector 5, the light homogenizing device 6, the second reflector 7, and the light combination device 8 arranged in sequence along the second light direction together constitute a light recovery device and are used to convert the second The light is transmitted to the second spatial light modulator 3 . The light recovery device is located between the first spatial light modulator 2 and the second spatial light modulator 3 .

After receiving the first light and the second light, the second spatial light modulator 3 modulates them again, and finally forms an image through the post-processing device 4 .

The second part of the embodiment:

Generally, a frame of color image includes three monochrome image frames of red, green and blue. Images can be modulated in the following two ways.

In the first way, three colors of light of red, green and blue are provided sequentially, and a set of modulation devices are used to modulate the three colors of light of red, green and blue according to the three monochromatic image frames of red, green and blue respectively.

The second way is to provide red, green and blue three-color light on three optical paths at the same time, and use three sets of modulation devices to modulate red, green and blue three-color light according to red, green and blue three monochrome image frames respectively. For light, a set of modulation devices is set on each optical path.

The structural diagram shown in FIG. 2 is applicable to the first mode and to one optical path in the second mode.

Please refer to FIG. 3 . FIG. 3 is a schematic structural diagram of another embodiment of the dual spatial light modulation system of the present invention. The embodiment shown in FIG. 3 is basically the same as the embodiment shown in FIG. 2 , except that the light recovery device in the embodiment shown in FIG. 3 further includes a controllable attenuation device 9 and a control device (not shown).

The controllable attenuation device 9 is located between the dodging device 6 and the second reflector 7 . The controllable attenuation device 9 is used to attenuate the second light according to a specified attenuation parameter before the second light is transmitted to the light combination device 8, and control the recycling of the second light. The first spatial modulator 2, the first reflecting mirror 5, the uniform light device 6, the controllable attenuation device 9, the second reflecting mirror 7, the light combining device 8 and the second spatial light modulator 3 together form a set modulation device.

In one embodiment, a set of modulating devices is used to modulate the three colors of light of red, green and blue respectively according to the three monochrome image frames of red, green and blue of the second light.

Specifically, the source light provided by the light source 1 includes red light, green light, and blue light that are sequentially provided to the first spatial light modulator 2 within a frame of color image modulation period; the first spatial light modulator 2 Modulating the red light, green light and blue light respectively according to the three monochrome frame image data of red, green and blue contained in one color frame image data to form the first light for displaying the image emitted along the first path and the second light that is not used to display images emitted along the second path; the first reflector 5 receives the second light emitted along the second path, and reflects the second light to the uniform light device 6, and the uniform light The light device 6 performs uniform light on the second light; the controllable attenuation device 9 performs attenuation processing on the second light after uniform light processing, to obtain the second attenuated red light, the second attenuated green light and the second attenuated light Attenuating the blue light so that the light quantities of the second attenuated red light, the second attenuated green light and the second attenuated blue light obtained within a frame of color image modulation period are consistent; the second reflector 7 receives the second attenuated light The red light, the second attenuated green light and the second attenuated blue light synthesize the attenuated second light and reflect it to the light combination device 8; the light combination device 8 receives the above-mentioned attenuated second light, and receives The first light combines the received attenuated second light with the first light; the second spatial light modulator 3 receives the combined light, modulates it again, and finally passes The post-processing device 4 forms an image.

In another embodiment, three light paths of red, green and blue are provided at the same time, and three sets of modulation devices are used to modulate the three kinds of red, green and blue according to the three monochromatic image frames of red, green and blue respectively. For light of different colors, a set of modulation devices is set on each light path. Each modulation device includes the first spatial modulator 2, the first reflector 5, a uniform light device 6, a controllable attenuation device 9, a second reflector 7, a light combination device 8 and a second spatial light Modulator 3,

Specifically, the source light provided by the light source 1 includes three lights of three colors: red light, green light and blue light, which are respectively provided to three sets of the modulation devices. Red light, green light and blue light can be provided by three light sources 1 respectively; one source light can also be provided by one light source 1, and then split into three colors of light by a prism: red light, green light and blue light, all of which are feasible Yes, the specific form is not limited, and the principle is the same.

Each of the first spatial light modulators 2 in the three sets of modulation devices respectively receives red light, green light and blue light and modulates the red light, green light and blue light according to the corresponding color frame image data. That is to say, the three colors of red light, green light and blue light respectively pass through the three first spatial light modulators 2 at the same time.

For example, the modulation process of red light: the red light passes through a first spatial light modulator 2, and the first spatial light modulator 2 modulates the red light according to the red frame image data to form The first red light for displaying images and the second red light not used for displaying images emitted along the second path; the first reflector 5 receives the second red light emitted along the second path and reflects The red light second light is sent to the uniform light device 6, and the light uniform device 6 performs uniform light on the red light second light; the controllable attenuation device 9 uniformly processes the red light second light. The light is attenuated according to the requirements to obtain the second attenuated red light; the second reflector 7 receives the second attenuated red light and reflects it to the light combining device 8; the light combining device 8 receives the above attenuated red light After receiving the second attenuated red light, and receiving the first red light, combining the received attenuated second attenuated red light with the first red light; the second spatial light modulation The device 3 receives the combined light and modulates it again. The red light modulated above finally passes through the post-processing device 4 to form an image.

The modulation process of green light is the same as the modulation process of red light above;

The modulation process of blue light is the same as the modulation process of red light above;

Certainly, in the whole system, during the process of modulating the red light, green light and blue light respectively by the three sets of modulation devices, a control device can be added to control the attenuation parameters, and the three sets of modulation devices share one control device that is Can.

Therefore, in this embodiment, the second light is actually carried out by three light paths at the same time, and each light path includes a second light (corresponding to the second light modulated by red light, the second light modulated by green light and the blue light respectively). modulated second light). The three second lights of the three optical paths respectively pass through the first reflector 5, the uniform light device 6, the controllable attenuation device 9, the second reflector 7 and the light combination device 8 on the respective optical paths to complete the corresponding light processing. The light processing process of the optical path is the same as the process of the above-mentioned embodiment using a set of modulation devices for modulation. In this embodiment, three sets of modulation devices are used to modulate the three second lights respectively. The principles are the same and will not be repeated here. .

Because each frame of color image includes three monochrome image frames of red, green and blue, each monochrome image frame has a different proportion of recycled light, that is, different attenuation parameters. A relatively dark image frame can recover a larger proportion of light, because the spatial light modulator modulates a relatively dark image frame to form more light that is not used to display an image; and a relatively bright image frame can recover a smaller proportion of light . For each frame of color image, a control device is required to control and adjust the ratio of light quantities that can be recycled for the three monochromatic image frames. The control device calculates the ratio of the recyclable light of each monochromatic image frame in each color frame=not used Light to display the image / (light used to display the image + light not used to display the image). Of course, the dual-spatial light modulation system of the present invention does not necessarily have a control device, and can also directly read the proportions of light quantities of the three monochromatic image frames that can be recovered in a fixed form through other components, as long as the three monochromatic image frames can be read. The ratio of the amount of light that can be recycled for an image frame is sufficient.

The controllable attenuation device 9 respectively reads the recyclable ratios of the red, green and blue colors of the second light, and calculates the recycling ratios of the red, green and blue colors of the second light. It is adjusted to be consistent through timing adjustment or three optical paths respectively.

By using the controllable attenuation device 9 to control the amount of recycled light, the brightness and contrast in the dual spatial light modulation system of the present invention can be further adjusted to achieve a desired balance state.

In this embodiment, the controllable attenuation device 9 may use a whole controllable liquid crystal panel. The liquid crystal panel is a liquid crystal imaging device used to synthesize red, green and blue light into the color of the image. The controllable liquid crystal sheet can control the color brightness of the synthesized image.

For example, the recyclable light ratio corresponding to the red frame image data is 20%, the recyclable ratio corresponding to the green frame image data is 40%, and the recyclable ratio corresponding to the blue frame image data is 60%. Then three attenuation parameters for controlling the attenuation of red light, green light and blue light can be generated respectively, which are: 0%, 50% and 67%. Attenuation parameter=(light quantity received by the controllable attenuation device−light quantity emitted)/light quantity received.

See in conjunction with Figure 4, an image diagram of the projection display. Generally, the projected image will have areas with different light and dark areas. Assume that the image to be projected and displayed is as shown in FIG. 4 , areas 101 , 102 , and 104 are all dark, and area 103 is all bright. Assume that the light transmission efficiency of the first spatial light modulator 2 and the second spatial light modulator 3 are both 70%, and the contrast ratio is 100:1. If only one spatial light modulator is used to display the image shown in FIG. 4 , it is assumed that the brightness of area 103 on the screen is x. Then the luminance of areas 101, 102 and 104 is 1%x.

If two spatial light modulators are used to display the image shown in Fig. 4, the brightness of area 103 on the screen is 70%x, and the brightness of the brightest point of the image decreases. While the brightness of areas 101, 102 and 104 is 0.007%x, the system contrast ratio can be increased up to 10000:1. But in fact, there is always some stray light in the environment of the projection system, so the high contrast cannot be well reflected.

If two spatial light modulators added with light recovery devices are used to display the image shown in FIG. 4 and the recycled light is not attenuated by the controllable attenuation device, the brightness of area 103 is 122.5%x. So the brightest point of the image projected by the system may even be brighter than the brightest point of the image displayed by a single-chip spatial light modulator. And the luminance of 101, 102 and 104 areas is 0.525% x, the contrast ratio of the system is 233:1, which will be higher than the contrast displayed by a single spatial light modulator, but lower than the contrast displayed by two spatial light modulators without a light recycling device .

Therefore, the light recycling device sacrifices contrast and improves brightness in a system of two spatial light modulators. In practical applications, too high contrast is often not well reflected due to ambient stray light. By adjusting the controllable attenuation device 9 in Figure 2 to control the amount of recycled light, the contrast and brightness can be adjusted in the system to achieve the best balance.

The third part of the embodiment:

Please continue to refer to Fig. 3, which is basically the same as the second part of the embodiment, the difference is that the first spatial light modulator 2 in this embodiment adopts DMD (Digital Micro-mirror Device, digital micromirror device), including multiple Micromirror units (not shown), each micromirror unit corresponds to a pixel in the image. The micromirror unit can be in an ON (open) state and an OFF (closed) state. When in the ON state, the light beam is reflected to the projection lens, and when in the OFF state, the light beam is reflected to another optical path. In one modulation period, the time or times that the micromirror unit is in the ON state is proportional to the grayscale value of the pixel.

Since the first spatial light modulator 2 in this embodiment uses a DMD, the corresponding light combination device 8 is different. The light combination device 8 may be a reflector with a through hole in the middle. The first light formed after being modulated by the first spatial light modulator 2 can pass through the middle hole of the light combining device 8 and hit the second spatial light modulator 3 . In this embodiment, the through hole is located in the middle of the reflector, but the present invention is not limited thereto, and in other embodiments, the through hole may also be located in other positions.

The second light passes through the first reflector 5 , the uniform light device 6 , the controllable attenuation device 9 , the second reflector 7 and the light combination device 8 , and is finally reflected to the second spatial light modulator 3 . Since there is a through hole in the middle of the light combination device 8, the second light will be lost in the recycling process. The settings of the characteristics of the second reflector 7 and the light combining device 8 can refer to the above-mentioned embodiments, and will not be repeated here.

In this way, by using the dual spatial light modulation system of the present invention, an image output with relatively balanced contrast and brightness can be obtained.

In addition, the present invention also proposes a method for light adjustment using the above-mentioned dual spatial light modulation system, including the following steps:

The present invention also provides a method for light adjustment using the above-mentioned dual-spatial light modulation system, wherein the light recovery device includes an optical path conversion component, a light combination device 8, a light homogenization device 6 and a controllable attenuation device 9, and the light path The conversion assembly includes a first reflector 5 and a second reflector 7, and the method comprises the following steps:

Step S1 , providing source light, and emitting the source light through the light source 1 .

Step S2, source light modulation, the source light is modulated by the first spatial light modulator 2 to form the first light emitted along the first path for displaying images and the light emitted along the second path not used for display Image in second light.

Step S3, combining light, receiving the second light emitted along the second path through the light recovery device, guiding the second light to combine with the first light, and combining the first light with the The combined light of the second light is transmitted to the second spatial light modulator 3 .

More preferably, this step specifically includes:

Step S31 , receiving the second light emitted along the second path through the optical path conversion component and changing the optical path of the second light, so that the second light is transmitted to the light combining device 8 .

Specifically in this step, the second light emitted along the second path reflected by the first reflector 5 is received by the second reflector 7, and the optical path of the second light is changed so that the first The two lights are reflected to the light combining device 8 .

Step S32 , performing uniform light processing on the second light by the light homogenizing device 6 before the second light is transmitted to the light combining device 8 .

Step S33 , performing attenuation processing on the second light according to a specified attenuation parameter before the second light is transmitted to the light combination device 8 by the controllable attenuation device 9 .

Step S34 , receiving the second light and the first light transmitted by the optical path conversion component through the light combination device 8 , and performing light combination processing on the received second light and the first light.

It should be noted that the order of steps S32 and S33 can be changed. For example: the optical path conversion component receives the second light emitted along the second path, and then the second light passes through the light dodging device 6 for uniform light treatment, and then passes through the controllable attenuation device 9 for the The second light undergoes attenuation processing, and finally receives the second light through the light combination device 8 .

In this embodiment, the light successively passes through the first reflector 5, the uniform light device 6, the controllable attenuation device 9, the second reflector 7 and the light combination device 8, and finally reflects to on the second spatial light modulator 3 .

Step S4, light display, receiving and modulating the composite light synthesized by the first light and the second light processed in step S3 by the second spatial light modulator 3 to form image light and projecting it to screen display.

Compared with related technologies, in the dual-spatial light modulation system and the light adjustment method using the system of the present invention, the light recycling device is added, and the second light emitted along the second path is received by the light recycling device. light, and guide the second light to combine with the first light, and transmit the combined light of the first light and the second light to the second spatial light modulator; further through the The second spatial light modulator receives the combined light of the first light and the second light, and modulates the combined light of the first light and the second light to form an image for projection onto a screen The dual spatial light modulation system can adjust the relative balance of contrast and brightness according to the needs of use.

It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the present invention rather than limit the scope of the present invention. Those of ordinary skill in the art should understand that without departing from the spirit and scope of the present invention Any modifications or equivalent replacements made to the present invention shall fall within the scope of the present invention. Further, words appearing in the singular include the plural and vice versa unless the context otherwise requires. Additionally, all or a portion of any embodiment may be utilized with all or a portion of any other embodiment, unless stated otherwise.

Claims (17)

1. A dual spatial light modulation system comprising a light source, a first spatial light modulator, a second spatial light modulator, and a light recycling device,

the light source is used for providing source light;

the first spatial light modulator is used for modulating the source light to form first light which is emitted along a first path and is used for displaying an image and second light which is emitted along a second path and is not used for displaying the image;

the light recovery device is used for receiving the second light emitted along a second path, guiding the second light to be combined with the first light, and transmitting the combined light of the first light and the second light to the second spatial light modulator;

the second spatial light modulator is configured to receive a combined light of the first light and the second light, and modulate the combined light of the first light and the second light to form an image light for projection to a screen.

2. The dual spatial light modulation system of claim 1 wherein the light recycling device comprises:

the light path conversion component is used for receiving the second light emitted along a second path and changing the light path of the second light so that the second light is transmitted to the light combining device; and the number of the first and second groups,

the light combining device is configured to receive the second light transmitted by the optical path conversion component, receive the first light, and combine the received second light with the received first light.

3. The dual spatial light modulation system of claim 2 wherein the optical path conversion assembly comprises:

the first reflector is used for receiving the second light emitted along the second path and reflecting the second light;

and the second reflector is used for receiving the second light reflected by the first reflector and further reflecting the second light to the light combining device.

4. The dual spatial light modulation system of claim 2 wherein the light recycling device further comprises:

and the light homogenizing device is used for homogenizing the second light before the second light is transmitted to the light combining device.

5. The dual spatial light modulation system of claim 2 wherein the light recycling apparatus further comprises:

and the controllable attenuation device is used for carrying out attenuation processing on the second light according to a specified attenuation parameter before the second light is transmitted to the light combination device.

6. The dual spatial light modulation system of claim 5,

the source light comprises red light, green light, and blue light provided to the first spatial light modulator in time sequence within a frame of color image modulation period;

the first spatial light modulator modulates the red light, the green light and the blue light respectively according to three monochromatic frame image data of red, green and blue contained in one color frame image data;

the controllable attenuation device is used for carrying out attenuation processing on the second light formed by respectively modulating the red light, the green light and the blue light by the first spatial light modulator to obtain second attenuated red light, second attenuated green light and second attenuated blue light, so that the light quantities of the second attenuated red light, the second attenuated green light and the second attenuated blue light obtained in a frame of color image modulation time period are consistent.

7. The dual spatial light modulation system of claim 5 comprising three sets of modulation devices, each set of modulation devices comprising the first spatial light modulator, a light recycling device, and the second spatial light modulator;

the source light comprises red light, green light and blue light respectively provided to the three sets of modulation devices simultaneously during a frame color image modulation period;

the first spatial light modulator in the three sets of modulation devices respectively modulates the red light, the green light and the blue light according to three monochromatic frame image data of red, green and blue contained in a color frame image data;

the controllable attenuation devices in the three sets of modulation devices respectively perform attenuation processing on second light formed by the red light, the green light and the blue light modulated by the corresponding first spatial light modulator to obtain second attenuated red light, second attenuated green light and second attenuated blue light, so that the light quantities of the second attenuated red light, the second attenuated green light and the second attenuated blue light obtained in a frame color image modulation period are consistent.

8. The dual spatial light modulation system of claim 6 or 7, further comprising:

and the control device is used for calculating the recoverable light proportion corresponding to the three monochromatic frames of red, green and blue contained in each color image data respectively, and controlling the controllable attenuation device to perform attenuation processing according to the lowest recoverable light proportion so as to enable the light quantities of the second attenuated red light, the second attenuated green light and the second attenuated blue light obtained in one frame of color image modulation time interval to be consistent.

9. The dual spatial light modulation system of claim 2 wherein the first spatial light modulator is an LCD or an LCOS.

10. The dual spatial light modulation system according to claim 9, wherein the light combining device is a polarization light combining device, the first light transmitted to the light combining device has a first polarization state, the second light transmitted to the light combining device has a second polarization state, and the light combining device is configured to combine the first light having the first polarization state and the second light having the second polarization state.

11. The dual spatial light modulation system of claim 1 wherein the first spatial light modulator is a DMD.

12. The dual spatial light modulation system of claim 2 wherein the light combining means is a mirror with a through hole;

the first light is incident to the second spatial light modulator through the through hole, the second light is reflected to the second spatial light modulator by the reflector, or,

the second light is transmitted through the through hole and is incident to the second spatial light modulator, and the second light is reflected to the second spatial light modulator through the reflector.

13. The dual spatial light modulation system of claim 12 wherein the first mirror is a planar mirror; or,

the first reflector is a curved reflector;

a first light spot of the first light projected on the second spatial light modulator has an overlapping region with a second light spot of the second light projected on the second spatial light modulator.

14. The dual spatial light modulation system of claim 3 wherein the second mirror is a planar mirror; or,

the second reflector is a curved reflector.

15. The dual spatial light modulation system of claim 5 wherein the controllable attenuation device is an integral piece of controllable liquid crystal.

16. The dual spatial light modulation system of claim 3 wherein the angle between the first mirror and the second mirror is 90 °.

17. A method of light modulation comprising the steps of:

providing source light, emitting source light by the light source;

source light modulation, which makes the source light modulated by the first spatial light modulator to form a first light emitted along a first path and used for displaying images and a second light emitted along a second path and not used for displaying images;

the light combining device is used for receiving the second light emitted along a second path, guiding the second light to combine with the first light, and transmitting the combined light of the first light and the second light to the second spatial light modulator;

and light display, receiving the combined light synthesized by the first light and the second light through the second spatial light modulator, modulating the combined light, forming image light and projecting the image light to a screen for display.