JP2010511913A - Modulator device and apparatus for three-dimensional display system - Google Patents

Abstract

  A modulator and apparatus comprising a tunable diffraction grating (TDG) element disposed with a plurality of individual modulator portions and a prism with appropriate color and polarization filters, at least two independent overlapping Generate 2D video to form a 3D display for 3D video.

Description

  The present invention relates to a line scanning projection display system, and in particular, separates and recombines different colors and / or polarization states of a tunable diffraction grating (TDG) element and a light source embedded as one component. Or a line scanning projection system for generating a three-dimensional image, including a modulator with a specially designed prism for separation / recombination.

In recent years, video projectors, especially digital projectors, have come to be widely used as means for presenting various information to the audience. In general, such a projector is used to project a computer generated image on a plane. With the video projector, the user can easily present high-quality video to various audiences. For this reason, such projectors are often a permanent item in conference rooms and other meeting facilities.
An image projected by an ordinary image projector generally looks flat and two-dimensional to the viewer, and does not represent any depth other than the depth of field of the image. Such a representation may be suitable for many applications, but in some cases it may be desirable to emphasize features such as depth and texture of the image even more than ordinary two-dimensional representations.

  There are already several methods for generating 3D images. For example, a two-dimensional representation of a video can be viewed deeply by expressing the video three-dimensionally. Such images include separate images of the left and right eye images superimposed, and the left and right eyes of a person are separated so that the left and right eyes can see slightly different 3D objects. ing. Generally, a person wears glasses as an optical filter, and the left eye image and the right eye image are respectively presented so that the left eye image cannot be seen by the human right eye and the right eye image cannot be seen by the left eye.

  For example, a three-dimensional image can be presented by projecting a left-eye image and a right-eye image using separate projection systems in a conference room. Such a system is convenient for forming a stereoscopic image, but the price and weight of the system are considerably larger than a single projector. Further, when two projectors are used, optical adjustment is difficult and time may be required. In addition, such a system has a problem that it is difficult to move a place because of the weight and size of two systems, and it is difficult to adjust an image if the place is changed.

  Another example of a prior art 3D video system uses a single projector and places an active polarizing sheet between the projector and the screen. The polarizing sheet circularly polarizes every other video frame in the reverse direction. Since the right and left eyes of people wearing polarized glasses see every other frame, a stereoscopic 3D image can be seen on the screen. However, since the polarizing sheet absorbs a part of the light, the light efficiency decreases. In addition, when every other frame is displayed in a different eye, the video flickers and artifacts are mixed. Also, the response of the display modulator must be twice as fast as the response of the modulator used in the two projector configuration. This is because the refresh rate of one projector image must be twice as fast.

  A stereoscopic projector that uses a laser as a light source has a much larger color area than current projectors, and therefore can generate images with more natural saturated colors. EP0211596A discloses an apparatus for generating a stereoscopic image including a 610 nm red laser (23), a 514 nm green laser (24) and a 476 nm blue laser (25). The light from the laser (23, 24, 25) is modulated by one first-order light beam and two first-order light beams by the first set of acoustic modulators (26, 27, 28). The first set of acoustic modulators (26, 27, 28) is adjusted so that the primary light beam has a certain launch angle for the same 0th order light beam for all primary colors. For the light that has not been diffracted, the first set of lenses (30, 31, 32) converts the light from the first set of photoacoustic modulators (26, 27, 28) into the second set of lenses (36). , 37, 38) and a set of stoppers (33, 34, 35).

  The second set of lenses (36, 27, 38) focuses the light to a point just in front of the beam scanner (52). The light beam (39, 40) from the second lens (36) passes through the polarization rotor (41) and then passes through the polarization splitter (42). The first set of polarized light (43, 44) is modulated by the second photoelectric modulator (47), and the second set of polarized light (45, 46) is orthogonally polarized with respect to the first set of polarized light. Is reflected toward the third photoelectric modulator (49) by the reflector (48). The mirrors (50, 51, 53) collect the light (43, 44, 45, 46), direct the collected light to the first scanner (52) and further through the projection system. The user can view the video through glasses with different polarization filters for each eye. The polarization corresponds to the polarization introduced into the device.

GB 2265024A discloses a modulator comprising a first transmissive layer (1) and a second deformable layer (5) at a distance (6) from the inside of the first transmissive layer (1). Yes. There is a prism (9) on the first transmission layer (1). The deformable layer (5) deforms when a signal is applied.
US 2004 / 0008928A discloses an apparatus (10) for separating light (26 ') with different wavelengths from an incident light beam (26). The substrate (12) has a layer structure (14), and each part of the layer structure (14) has a different optical function to separate and control the polarization.
WO / 90 / 03086A discloses an apparatus (1) for reproducing stereoscopic images with a line scanning projection system. This device comprises a number of fields of view (5) with a separation unit (6) with a polarizing filter. In front of each separation unit is a double-sided display (14).

EP0211596A GB22665024A US2004 / 0008928A WO / 90 / 03086A Norwegian Patent Application No. 20054834

In summary, conventional methods of generating stereoscopic images on a projection display generally use a complex and expensive multi-path system or a single chip with insufficient brightness and long response time.
Therefore, there is a need for a simple, low-cost stereoscopic projection system for creating and displaying an image with a wide color area and no flicker.
In the prior art, a single panel DMD (digital micromirror device) system is used for three-dimensional stereoscopic projection. In this case, the individual left / right frames for each eye are displayed sequentially. When the user puts on glasses having a shutter function synchronized with the projector, the left eye can see the displayed image only when the projector displays the “left eye frame”. The same applies to the right eye.

However, such a method requires more than twice the bandwidth of the projector / display modulator and the electronic circuit. This is because to avoid flickering artifacts, the frame rate needs to be twice that of “monoscope” video, so in practice the current DMD elemental technology, for example, has a full HDTV resolution of more than full 8 bits. It cannot be displayed in grayscale resolution.
Another example of the prior art uses a combination of stereographic left-eye and right-eye separation and a single panel DMD system. The viewer wears glasses with matching color bands. However, the luminance efficiency is very low with a white light source. Since this system is a sequential operation mode, the response speed of the display modulator and drive electronics needs to be very fast, which means limited bit depth for gray scale resolution.

Another example of the prior art uses two LCOS (Liquid Crystal On Silicon) displays, and separates the left eye and the right eye with glasses having passive polarization filters on the viewer side of the system. Match the left / right output from the projector. This is because the polarization of incident light to both LCOS modulators is orthogonally polarized.
In this case, color and brightness uniformity and thermal stability, as well as polarization separation / recombination from the two displays are very important. This means that the optical system is complex. Response speed is also a problem. This is because each LCOS modulator must display full RGB color frames within a predetermined frame rate.

One aspect of the present invention provides a system for producing a single chip 3D image that is separated by polarization, color bands, or a combination thereof.
A preferred example of an embodiment of the invention uses a tunable diffraction grating (TDG), in particular the grating described in Norwegian patent application No. 20054834. The principle of operation of this tunable diffraction grating is based on light diffraction by surface modulation of a thin gel layer or film with equal optical and functional properties. The basic principles of such modulators are well known and have been used in projection applications since the introduction of the Eidophor project over 60 years ago.

  In an example embodiment of the invention, a specially designed prism is used for separation and recombination, or as a combined separation / recombination element for different colors and / or polarization states from a given light source. This scheme is formed by a single element. Individual colors and / or polarization states from the light source are directed towards individual modulator portions on a single TDG surface. Using a prism as part of the modulator requires very little centering adjustment and makes the system very compact.

In one aspect of the invention, this concept simplifies the optical system and reduces the cost, difficulty and investment of the product assembly process.
In another aspect of the present invention, the system complexity and cost are lower than those of a multi-chip system, and there is an advantage that a high response speed is not required as in the current single-chip system and a refresh speed is improved. It is not limited to these.
In another embodiment of the present invention, a stereoscopic image can be created by using a combination of polarization and color separation. The effect of this property is that individual videos can be presented to different audience groups, for example by providing a “presenter mode” where the presenter can access more video content than the audience.

1 shows an example of an embodiment of a modulator device according to the invention based on polarization separation. 4 shows another example of an embodiment of a modulator device according to the invention based on polarization separation. 3 shows an example of an embodiment of a color projection system including a modulator design according to FIG. 4 shows another example of an embodiment of a modulator device according to the invention based on color separation. Fig. 4 shows another example of an embodiment of a modulator device according to the present invention based on color and polarization separation.

  One aspect of the invention uses a TDG modulator that includes a set of electrodes at a functional distance from a gel, membrane, polymer, or the like. When an appropriate voltage is applied to the electrode, a diffraction grating is formed on the surface of a gel or a film. One feature of such TDG modulators is that multiple groups of independent electrodes can be inserted at a functional distance from the gel or membrane so that the various surfaces of the gel or membrane above the individual groups of electrodes It is to diffract each light incident on the portion individually. Thus, in one example of an embodiment of the present invention, an incident light beam (eg, a laser) is separated and polarized, and then this polarized beam is directed toward a respective portion of the TDG element gel or film surface. Thus, the left-eye and right-eye images can be modulated respectively. For example, optical elements placed before and / or after the modulator are the devices necessary to form a three-dimensional projection system. In one aspect of the invention, such a modulator can be arranged as a single chip element.

  FIG. 1 shows an example of a single chip embodiment of a modulator device according to the invention based on polarization separation. Laser light 1 is incident on the modulator prism. This light is reflected by the polarizing filter 2. Polarization filter 2 splits the beam into two separate polarization beams (1s and 1p), whose individual polarization states are orthogonal to each other. Each beam is incident on a separate modulation portion of the single TDG modulator surface 4. The angle of the diffracted laser beam can be controlled by different grating patterns obtained from the voltages applied to the electrodes 3s and 3p. A three-dimensional effect is obtained by viewing this diffracted light through a suitable optical element as is well known to those skilled in the art.

FIG. 2 shows another example of an embodiment of a single chip modulator device according to the present invention based on polarization separation. Red, green and blue laser beams 5 are incident on the modulator prism. This light is reflected by the stack of polarization color filters 2. As a result of the reflection, the incident light 5 is separated into six separate beams 4R _s , 4R _p , 4G _s , 4G _p , 4B _s and 4B _p . Each beam is characterized by a unique combination of wavelength and polarization state. The polarization state of each wavelength is orthogonal to each other. Each beam is then incident on a separate modulation portion of the TDG modulator surface 4. As is well known to those skilled in the art, electrodes _{3R s, 3R p, 3G s} , 3G p, 3B s, with different grating patterns obtained from the voltage applied to 3B _p, to control the angle of the diffracted laser light beams, respectively it can. FIG. 3 shows an example of a three-dimensional display system according to the present invention including the modulator shown in FIG.

  In FIG. 3, the different laser colors R, G, B (red, green, blue) are aligned coaxially with the help of two dichroic filters 9R, 9G (for this alignment, for example, an X prism Other elements may be used, etc.), leading to modulator 11 through beam shaping relay optics (common to all colors) 10. The modulator 11 separates this beam into its color and polarization components, and individually modulates the different beams before directing them towards the projection optics 12. A schlieren stop 13 is used to filter out undesired diffraction orders, and a scanning mirror 14 is used to overlay two two-dimensional image overlays with orthogonal polarization characteristics on the polarization maintaining screen 15. Generate.

  A 3D image is created when a person wears passive polarizing glasses. The individual glasses of the glasses polarize the transmitted light orthogonal to each other, and with respect to the polarization stack in the modulator, the light from one projected image only enters the person's left eye, and the light from another projected image is It is configured to enter only the right eye of a person. As is well known to those skilled in the art, when the left eye sees an image different from the image of the right eye, a three-dimensional image is created due to the stereoscopic effect.

FIG. 4 shows another example of an embodiment of a modulator device according to the invention based on color separation. Six coaxially aligned laser beams (two red, two green, two blue) 7 having different wavelengths are incident on the modulator prism. This light is reflected by the stack of color filters 8. As a result of the reflection, the incident light 7 is separated into six separate beams 7R ₁ , 7R ₂ , 7G ₁ , 7G ₂ , 7B ₁ , 7B ₂ having different wavelengths. Each beam is then incident on a separate modulation portion of the single TDG modulator surface 4. The electrodes _{3R 1, 3R 2, 3G 1} , 3G 2, 3B 1, different lattice patterns obtained from the applied voltage to 3B _2, separate (or different) to control the angle of the diffracted laser light beam having a wavelength it can.

Two overlapping two-dimensional images are projected on the screen using the same projection optical element as in the projection system shown in FIG. A 3D image is created when a person wears passive filtering glasses. Since the individual glasses of the glasses pass different wavelengths, the right eye (for example) sees an image made with colors 7R ₁ , 7G ₁ , 7B ₁ and the left eye (for example) is made with colors 7R ₂ , 7G ₂ , 7B ₂ Watch the video. As is well known to those skilled in the art, when the left eye sees an image different from the image of the right eye, a three-dimensional image is created due to the stereoscopic effect.

FIG. 5 shows another example of an embodiment of a modulator device according to the present invention based on color and polarization separation. Six coaxially aligned laser beams (two red, two green, two blue) 16 having different wavelengths are incident on the modulator prism. This light is reflected by the stack of color and polarization filters 17. As a result of reflection, the incident light 16 is divided into 12 separate beams 16R _1s , 16R _1p , 16G _1s , 16G _1p , 16B _1s , 16B _1p , 16R _2s , 16R _2p , 16G _2s , 16G _2p , 16B _2s , 16B _2p To separate. Each beam has a unique combination of wavelength and polarization state. The polarization state of each wavelength is orthogonal to each other. Each beam is characterized by a unique combination of wavelength and polarization state.

The polarization state of each wavelength is orthogonal to each other. Each beam is then incident on a separate modulation portion of the single TDG modulator surface 4. Diffractive lasers with different grating patterns obtained from voltages applied to electrodes 3R _1s , 3R _1p , 3G _1s , 3G _1p , 3B _1s , 3B _1p , 3R _2s , 3R _2p , 3G _2s , 3G _2p , 3B _2s , 3B ₁ Each angle of the light beam can be controlled. Using the same projection optical element as in the projection system shown in FIG. 3, four overlapping two-dimensional images are projected onto the polarization maintaining screen. A 3D image is created when a person wears passive filtering glasses. The individual glasses of the glasses pass through a combination of different wavelengths and different polarization states.

A person's right eye (eg) sees an image made up of a combination of color and polarization (eg, 16R _1s , 16G _1s , 16B _1s ), while the left eye sees a combination of color and polarization (eg, 16R _2s , 16G _2s , 16B Watch the video made in _2s ). The right eye of another person wearing different glasses sees an image made up of a combination of color and polarization (eg 16R _1p , 16G _1p , 16B _1p ) and the left eye sees a combination of color and polarization (eg 16R _2p , 16G _2p , 16B _2p ). When the left eye sees a video that is different from the video for the right eye, a 3D video is created for each person who sees it due to the stereoscopic effect. Since four different two-dimensional images overlap, two different three-dimensional images can be presented to a person wearing different glasses. This can be used for many applications. For example, multitasking in which individual videos containing information are presented to different groups of people, or “presenter mode” where the presenter can access more video content than the audience.

In one aspect of the present invention, using the characteristics of the TDG modulator, at least two electrode groups relating to each state of light constituting an image to be displayed are provided, an appropriate voltage is applied to each electrode group, After controlling the angle of the diffracted laser light beam, it is passed, for example, through display optics and a scanning mirror array. In another example of the embodiment of the present invention, the angle of each diffracted light beam is controlled by the arrangement of the electrode pattern with respect to the diffracted light beam.

Claims (12)

A modulator device for generating a three-dimensional image viewed by a user through an optical filter in a line scanning projection system, having a plurality of individual electrode groups and forming a plurality of individual modulator portions therein A tunable diffraction grating (TDG) element (4);
Each component that results from the separation of the incident light that is directed to the reflecting element (2, 6, 8, 17) that is a prism and separates the incident light (1, 5, 7, 16) into its components. Is directed by the prism towards the corresponding modulation portion of the TDG element (4), and the angle of each diffracted light beam directed from the modulator device through the prism is controlled by the voltage applied to each electrode in each electrode group , A prism that performs polarization separation or color separation, or both polarization separation and color separation,
Including a modulator device.   The modulator device of claim 1, wherein the separation is performed by a stack of polarizing filters.   The modulator device of claim 1, wherein the separation is performed by a stack of color filters.   The modulator device of claim 1, wherein the separation is performed by a stack of color filters and polarizing filters.   The modulator device is arranged with one polarization filter (2) that reflects incident light (1) from one laser source and separates it into two separate polarization beams (1s, 1p), each beam ( The polarization states of 1s, 1p) are orthogonal to each other, the reflected beam (1s, 1p) is a modulator part (3s) that modulates (1s) of one reflected beam and another that modulates another reflected beam (1p) The voltage applied to each electrode group corresponding to each modulator portion (3s, 3p) is guided by the prism toward a modulator element (4) including a modulator portion (3p), and the modulator is passed through the prism. The modulator device of claim 1, wherein the modulator device controls an angle of the diffracted light beam directed from the device. The modulator device is arranged with a stack (6) of color polarizing filters that reflect and separate incident light (5) from one red, one green, and one blue laser light source, and the red laser The light is separated into two separate polarized beams (5R _s , 5R _p ) having mutually orthogonal polarization states, and the green laser light is separated into two separate polarized beams (5G _s , 5G _p ), the blue laser light is separated into two separate modulated beams (5B _s , 5B _p ) having mutually orthogonal polarization states, and the reflected beams (5R _s , 5R _p , 5G _s , _{5G p, 5B s, 5B p} ) is six modulator part for modulating the corresponding reflected light beams respectively _{(3R s, 3R p, 3G} s, 3G p, 3B s, the modulator element comprising 3B _p) ( 4) towards the pre Guided by beam, the prism respective diffracted light beams each modulator portion exiting from said modulator device _{(3R s, 3R p, 3G} s, 3G p, 3B s, 3B p) by voltage applied to the electrode in the The modulator device of claim 1, wherein the modulator device guides through the prism at a controlled angle. The modulator device is arranged with a stack of color filters (8) that reflects and separates incident light (7) from six coaxially aligned lasers with different wavelengths, the incident light (7) being two The color filter stack (8) includes six reflected light beams (7R ₁ , 7R ₂ , 7G ₁ , 7G ₂ , 7B ₁ , 7) including red, two green and two blue laser light sources. 7B ₂ ), the prism directs the six reflected light beams towards six independent modulator parts in the TDG modulator element (4), and each modulation in the TDG modulator element A voltage applied to an electrode in the vessel portion controls the angle of the diffracted light beam exiting the modulator device through the prism, the diffracted light beam being arranged by an optical element as two separate overlapping two-dimensional images. Item 1 Modulator device.   The modulator device is arranged with a stack of color and polarization filters (17) that reflect coaxially aligned laser beams with two red, two green and two blue different wavelengths, and a stack of filters (17). Produces twelve separate beams, each beam having a unique combination of wavelength and polarization state, and the prism includes the twelve independent modulator portions of the twelve reflected beams. The voltage to the electrodes in each of the twelve modulator sections controls the angle of the diffracted light beam exiting the modulator device through the prism, the diffracted light beam being in two different third orders The modulator device of claim 1, wherein the modulator device is arranged by an optical element as four separate overlapping two-dimensional images including the original image.   6. A modulator device according to any one of the preceding claims, wherein the angle of the diffracted light beam emerging from the modulator device is controlled by the placement of electrodes within each modulator portion.   A modulator device according to any one of the preceding claims, wherein the modulator device is formed as a single integrated electronic element.   Apparatus for generating a three-dimensional image in a line scanning projection system comprising a modulator device (11) according to claim 5, 6, 7 or 8, said apparatus comprising two dichroic filters (9R, 9B). ) To align the three different laser colors (red, green, blue) coaxially and then guide it through the beam shaping relay optics (10) towards the modulator device (11) 11) separates the beam into its color and polarization components, modulates the different beams individually and then directs the beam towards the projection optical element (12), after the schlieren after the projection optical element (12). A plurality of two-dimensional light beams having orthogonal polarization characteristics after a stop (13) filters out unwanted diffraction orders from the modulator portion in the modulator device (11) Formed through a scanning mirror (14) overlay the image on the polarization maintaining screen (15), apparatus for generating a three-dimensional image.   12. The apparatus according to claim 11, wherein the coaxial alignment is performed by an X prism.

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