TW201418845A - Directional waveguide-based backlight for use in a multiview display screen - Google Patents

Abstract

A directional waveguide-based backlight for use in a multiview display screen is disclosed. The directional backlight has a plurality of light sources to generate a plurality of input planar lightbeams. The plurality of input planar lightbeams illuminates a plurality of waveguide arrays having a set of waveguides. Each waveguide has a plurality of directional pixels to scatter the plurality of input planar lightbeams into a plurality of directional lightbeams. The directional lightbeams have a direction and angular spread controlled by characteristics of the directional pixels. The directional waveguide-based backlight can be used to generate a 3D image by specifying the characteristics of the directional pixels in the waveguides.

Description

Backlighting technology based on directional waveguide for multi-view display

The subject matter described herein relates to a directional waveguide based backlighting technique for use in a multi-view display screen. This application is related to PCT Patent Application No. PCT/US2012/035573 (Attorney Docket No. 82963238), filed on Apr. 27, 2012, entitled "Using directional directional elements for display screens", and The present application is also entitled "Backlight Technology for directional waveguides with integrated lasers for multi-view display screens" and is assigned to the assignee of the present application and incorporated herein by reference. PCT patent application.

The ability to display the reproduced light field in the screen has become a major exploration target in imaging and display technology. A light field is a collection of all rays of light that travel through each point in each direction in space. Any natural real world view can be fully scribed by its light field, and its light field provides information about the intensity, color and direction of all light passing through the scene. The purpose is to enable a viewer of a display screen to experience the scenery as one can experience.

Most of the display screens available on TVs, personal computers, notebook computers, and mobile devices still maintain a two-dimensional pattern, and therefore cannot be refined. Definitely reproduce a light field. Three-dimensional (3D) displays have recently been born, but suffer from insufficient angular and spatial resolution and can only provide a limited number of images. Examples include 3D displays based on stereo images, parallax barriers or lenticular lenses.

A common topic in these displays is the difficulty of fabricating light field displays that are controlled with pixel level accuracy to achieve good image quality over a wide range of viewing angles and spatial resolutions.

According to an embodiment of the present invention, a directional-based waveguide-based backlight for use in a multi-view display screen is specifically provided, including: a plurality of light sources for generating a plurality of input plane beams; and a plurality of waveguide arrays, each A waveguide array includes a plurality of waveguides, each waveguide comprising a plurality of directional directional elements of the patterned grating to scatter the plurality of input plane beams into a plurality of directional beams, each directional beam comprising the plurality of directions The direction and angular spread controlled by one of the directional elements in a sexual pixel.

100, 200, 300, 335, 500‧‧‧ directional backlight

105a-d, 305a-d, 340a-d‧‧‧ light source

110a-d, 310a-d, 345a-d‧‧‧ planar beam

115, 505a-c‧‧‧ Waveguide Array

120a-d, 205a-c, 315a-d, 350a-d, 400‧‧ ‧Band

125a-c, 210a-c, 320, 355, 420a-e‧‧‧ directional pixels

130a-c, 220a-c, 325, 360‧‧‧ directional beam

135a‧‧‧groove/grating

215a-c‧‧‧beam

330, 365‧‧3D images

405a-e‧‧‧Wave area

410‧‧‧Angle section

415a-b‧‧‧ horizontal section

510‧‧‧ observation section

600, 605, 610, 615‧‧ steps

L ‧‧‧raster length

W ‧‧‧raster width

Θ‧‧‧groove azimuth angle/grating azimuth angle

Λ‧‧·Grating pitch

△Θ‧‧‧ Angle spread

The present application will be more fully understood from the following detailed description in conjunction with the accompanying drawings in which FIG. 2 is a schematic view of a 3D view of an example backlight; FIG. 3A-B is a top view of the directional backlight according to FIG. 1; FIG. 4 is an example of a waveguide having a geometrically distinct area; Shown a multiple waveguide array having a waveguide including FIG. A schematic diagram of a directional backlight; and FIG. 6 is a flow diagram for generating a 3D image using a directional waveguide based backlight according to various examples.

A backlight based directional waveguide for a multi-view display screen is disclosed herein. The directional backlight uses a plurality of light sources to generate a plurality of input planar beams for a plurality of waveguide arrays. Each waveguide array consists of a set of waveguides. Each waveguide is composed of a plurality of directional pixels to direct the input planar beam and the scattered partial beam into an output directional beam. The input planar beam propagates in substantially the same plane as the directional floor designed to be substantially planar.

In various examples, the directional pixels have patterned gratings of substantially parallel and slanted trenches disposed in or at the top of the waveguide. The waveguide can be, for example, a dielectric or polymer waveguide or the like. The patterned grating may comprise a trench etched into the waveguide or a trench formed of a material deposited on top of the waveguide (e.g., any material that may be deposited and etched or removed, including any dielectric or metal).

In various examples, the plurality of light sources comprise a plurality of narrow bandwidth light sources having a spectral bandwidth of about 30 nm or less. For example, a narrow bandwidth light source can include a light emitting diode (LED), a laser, and the like. As described in more detail below, each directional pixel can be a grating length (i.e., a measure of the axis of propagation along the input plane beam), a grating width (i.e., a measure of the propagation axis across the input plane beam). , a groove orientation, a pitch, and a duty cycle. Each directional pixel can emit a directional beam whose direction is determined by the groove orientation and the grating pitch. The angular spread is determined by the length and width of the grating. Use one At a duty cycle of 50% or so, the second Fourier coefficient of the patterned grating disappears to prevent additional unwanted light scattering. This ensures that only one directional beam is emitted from each directional cell regardless of the output angle.

As described in further detail below, a directional backlight can be designed to contain directional pixels having a certain grating length, grating width, groove orientation, pitch, and duty cycle. Each directional pixel can produce a directional beam having a given field of view such that a plurality of directional pixels in the plurality of waveguides provide a plurality of pictures that form a multi-view 3D image. The multi-view 3D image may be a multi-view 3D image of red, blue, and green generated by a directional beam emitted by a directional pixel in the backlight.

It should be understood that in the following description, numerous specific details are set forth However, it should be understood that such examples may be practiced without limitation to these specific details. In other instances, well-known methods and structures may not be described in detail to avoid unnecessarily obscuring the description of the examples. Moreover, such examples can be used in conjunction with each other.

Referring now to Figure 1, a schematic diagram of a top view of a waveguide-based directional backlight in accordance with various examples is depicted. Directional backlight 100 includes light sources 105a-d to produce input planar light beams 110a-d for collimating waveguide arrays 115 composed of waveguides 120a-d. As generally described herein, a planar beam represents a beam of light in the beam that is substantially parallel to each other. The waveguides 120a-d can be dielectric or polymer waveguides having a plurality of directional pixel configurations thereon, such as if directional pixels 125a-c are disposed over the waveguide 120a. The directional pixels 125a-c scatter a portion of the input planar beam 110a into an output directional beam 130a-c.

In many examples, each directional pixel 125a-c has a patterned grating of substantially parallel grooves, such as grooves 135a for directional elements 125a. The groove thickness of the grating can be substantially the same for all grooves, resulting in a substantially planar design. The trenches may be etched in the waveguide or comprised of a material deposited on top of the waveguide (eg, any material that may be deposited and etched or removed, including any dielectric or metal).

Each directional beam 130a-c has a given direction and angular spread determined by the patterned grating in its corresponding directional pixels 125a-c. In particular, the direction of each directional beam 130a-c is determined by the orientation of the patterned grating and the grating pitch. The angular spread of each directional beam is determined by the length and width of the grating of the patterned grating. For example, the direction of the directional beam 130a is determined by the orientation of the patterned grating 135a and the grating pitch.

It is understood that such a substantially planar design and the formation of directional beams 130a-c based on input planar beam 110a require a grating having a substantially smaller pitch than conventional diffraction gratings. For example, conventional diffraction gratings scatter light by propagating a beam of light that substantially traverses the plane of the grating. Here, the grating in each of the directional pixels 125a-c is substantially in the same plane as the input planar beam 110a when the directional beam 130a-c is generated. This planar design allows illumination with light sources 105a-d.

In various examples, the light sources 105a-d can be narrow bandwidth sources such as LEDs. For example, the light source 105a can be a red LED, the light source 105b can be a green LED, the light source 105c can be a blue LED, and the light source 105d can be a white LED. Therefore, the directional light beams 130a-d from the waveguide 120a may be red beams, and the directional light beams from the waveguide 120b may be green beams, waves. The directional beam from the guide 120c may be a blue beam, and the directional beam from the waveguide 120d may be a white beam. As described below, directional pixels can be designed to provide precise control of the direction and angular spread of the directional beam, enabling multiple frames to be formed.

The directional beams 130a-c are precisely controlled by the grating properties of the directional pixels 125a-c comprising a grating length L , a grating width W , a groove orientation θ, and a grating pitch Λ. In particular, the grating length L of the grating 135a controls the angular spread ΔΘ of the directional beam 130a along the propagation axis of the input light, and the grating width W controls the angle of the directional beam 130a transverse to the propagation axis of the input light. The degree of development △ Θ, the formula is as follows: Here λ is the wavelength of the directional beam 130a. The orientation of the groove indicated by the grating azimuth angle θ, and the grating pitch or period specified by Λ, control the direction of the directional beam 130a.

The grating length L and the grating width W may vary in the range of 0.1 to 200 μm in size. The groove azimuth angle θ and the grating pitch Λ can be set to satisfy a desired direction of the directional beam 130a, wherein, for example, the groove azimuth angle θ is on the order of -40 to +40 degrees, and the grating pitch is at 200- 700nm grade.

It will be appreciated that the directional backlight 100 is shown for illustrative purposes only as one of the four waveguides 120a-d of the waveguide array 115. A directional backlight according to various examples can be designed to have many such waveguide arrays (eg, more than 100) depending on how the directional backlight 100 is used (eg, for 3D display) Screens, 3D watches, mobile devices, etc.). It should also be appreciated that the directional pixels can have any shape including, for example, a circle, an ellipse, a polygon, or other geometric shapes. Again, it is understood that any narrow bandwidth source can be used to generate input planar beams 110a-d (e.g., a laser or LED).

Figure 2 shows a 3D view of an example backlight. Backlight 200 is shown having a waveguide array comprised of waveguides 205a-c. Each waveguide has a plurality of directional pixels disposed thereon, such as directional cell 210a in waveguide 205a, directional cell 210b in waveguide 205b, and directional cell 210c in waveguide 205c. The directional pixels 210a-c can be designed to have different grating pitches and orientations. Each directional pixel 210a-c receives an input planar beam (e.g., beams 215a-c) and de-scatters the directional beams (e.g., directional beams) according to the grating pitch and orientation of each directional pixel. 220a-c). As described above, the directional beams 220a-c can thus generate a 3D image for a plurality of pictures. Each directional beam can be precisely controlled by the properties of its corresponding directional pixel.

Attention is now directed to Figures 3A-B, which show a top view of the directional backlight in accordance with Figure 1. In FIG. 3A, directional backlight 300 is shown with light sources 305a-d (eg, LEDs) that produce input planar beams 310a-d, and waveguides 315a-d that are comprised of a plurality of polygonal directional elements disposed thereon (this) The pixel is, for example, a directional pixel 320 in the waveguide 315a). Each directional pixel is capable of scattering a portion of the input planar beam into an output directional beam (e.g., a directional beam 325 scattered by the directional pixel 320 from the input planar beam 310a). The directional beam scattered by all the directional elements in the waveguides 315a-d can present a plurality of image frames, and when these images are combined, a 3D image is formed, such as a 3D image. Like 330.

Similarly, in FIG. 3B, directional backlight 335 is shown with light sources 340a-d (eg, LEDs) that produce input planar light beams 345a-d, and waveguides 350a that are comprised of a plurality of polygonal directional elements disposed thereon. d (This pixel is, for example, the directional pixel 355 in the waveguide 350a). Each directional pixel can scatter a portion of the input planar beam into an output directional beam (e.g., a directional beam 360 that is scattered by the directional pixel 355 from the input planar beam 345a). The directional beam scattered by all of the directional elements in the waveguides 350a-d can present a plurality of image frames that, when combined, form a 3D image, such as a 3D image 365.

In various examples, the waveguides in a waveguide array can be designed to have geometrically distinct regions. Each geometrically distinct region has a directional pixel that is perpendicular to the orientation of the region, thereby enabling the directional beam to have a different vertical orientation in each region. Figure 4 shows an example of a waveguide having a plurality of geometrically distinct regions. The waveguide 400 has geometrically distinct waveguide regions 405a-405e. Each waveguide region may have a single horizontal section, such as waveguide region 405a, or a plurality of segments having different orientations, such as waveguide regions 405b-e. The waveguide region 405b-e has an angular section disposed between the two horizontally oriented sections. For example, waveguide region 405e has an angular section 410 disposed between horizontal sections 415a-b.

Each waveguide region has a single directional pixel disposed thereon, such as directional pixels 420a-e. The directional pixels 420a-e placed in each waveguide region are oriented perpendicular to the orientation of the regions shown in the figures. a waveguide region (eg, region 405b-e) having an angular section between the two horizontal sections In the case of a directional pixel (e.g., pixel 420b-e), it is disposed perpendicular to the orientation of the angular segment. This allows the directional beam scattered by each directional element to have a different vertical orientation in each region.

Attention is now directed to Figure 5, which shows a schematic diagram of a directional backlight having a plurality of waveguide arrays comprising the waveguide of Figure 4. The directional backlight 500 is shown having a plurality of waveguide arrays 505a-c, and each waveguide array has four waveguides (eg, one for red light, one for green light, one for blue light, and the other for white light). . Waveguide arrays 505a-c can be designed to form different viewing sections, such as viewing section 510. Each viewing section may have directional pixels designed to scatter a directional beam into a given image frame to produce a 3D image.

A flow chart for generating a 3D image using a directional backlight in accordance with various examples is illustrated in FIG. First, the nature of the directional pixels of the directional backlight is specified (step 600). Such properties may include the properties of a patterned raster in a directional pixel, such as raster length, raster width, orientation, pitch, and duty cycle. As described above, each directional pixel in the directional backlight can be designated to have a given set of properties to produce a directional beam having a direction and angular spread that is precisely controlled according to such properties. Second, the directional backlight is fabricated to have a plurality of directional pixels disposed on the plurality of waveguides (step 605). The waveguides can be dielectric or polymer waveguides and the like. The directional pixels can be etched in the waveguide or formed of a patterned grating having a material deposited on top of the waveguide (the material is, for example, any material that can be deposited and etched or removed, including any dielectric or metal ). In various examples, the waveguide may also have geometrically distinct regions as shown in Figures 4-5. Light from multiple sources is input in the form of an input planar beam A backlight (step 610). Finally, a 3D image is generated from a directional beam of light scattered by the directional pixels in the directional backlight (step 615).

Advantageously, the precise control achieved by the directional pixels in the directional backlight enables a 3D image to be produced while making it easy to fabricate a substantially planar structure. Different configurations of directional pixels can produce different 3D images. The directional backlights described herein can be used to provide 3D images in a display screen (such as televisions, mobile devices, tablets, video game devices, and the like), and such as 3D watches, 3D art devices, 3D. 3D images are provided in other applications such as medical devices.

It is to be understood that the foregoing description of the disclosed examples is provided to enable any skilled person to make or use the invention. A variety of modifications to the examples are readily apparent to those skilled in the art, and the broad principles defined herein may be applied to other examples without departing from the spirit or scope of the invention. Therefore, the invention of the present application is not intended to be limited to the examples shown herein, but the broadest scope of the principles and novel features disclosed herein.

100‧‧‧ Directional backlight

105a-d‧‧‧Light source

110a-d‧‧‧ input plane beam

115‧‧‧Wave array

120a-d‧‧‧Band

125a-c‧‧‧ directional pixels

130a-c‧‧‧Directional beam

135a‧‧‧ trench

Claims (16)

A directional waveguide based backlight for use in a multi-view display screen, comprising: a plurality of light sources for generating a plurality of input plane beams; and a plurality of waveguide arrays, each waveguide array having a set of waveguides, each waveguide Having a plurality of directional pixels including a patterned grating to scatter the plurality of input plane beams into a plurality of directional beams, each directional beam having one of the plurality of directional pixels The nature controls one direction and angle spread. A directional waveguide based backlight of claim 1, wherein the plurality of light sources comprise a plurality of narrow bandwidth light sources. The directional waveguide based backlight of claim 1, wherein the plurality of waveguide arrays are substantially planar. A directional waveguide based backlight according to claim 1, wherein the patterned grating comprises a plurality of substantially parallel and inclined grooves. The directional waveguide based backlight of claim 4, wherein the properties of a directional pixel comprise a grating length, a grating width, a grating orientation, a grating pitch, and a duty cycle. A backlight based on a directional waveguide of claim 5, wherein the pitch and orientation of a directional pixel control a direction of a directional beam scattered by the directional element. The backlight of the directional waveguide according to claim 6, wherein the length and width of a directional pixel control a directionality of directional pixel scattering The angular spread of the beam. A directional waveguide based backlight of claim 1, wherein one of the set of waveguides comprises a plurality of geometrically distinct regions, each region having a plurality of segments and a single directional pixel. A method for generating a multi-view 3D image using a waveguide-based directional backlight, comprising: assigning a plurality of properties to a plurality of directional pixels, each directional pixel having a substantially parallel and inclined groove a patterned grating; manufacturing a directional backlight having one of the plurality of directional pixels disposed on the plurality of waveguides; illuminating the plurality of waveguides using light from the plurality of light sources; and using the directional backlight The directional light beams scattered by the plurality of directional pixels produce the multi-view image. The method of claim 9, wherein each directional beam is controlled by the properties of a directional cell. The method of claim 10, wherein the properties of a directional cell comprise a raster length, a raster width, a raster orientation, a grating pitch, and a duty cycle. The method of claim 11, wherein the pitch and orientation of a directional cell control the direction of the directional beam of the directional cell. The method of claim 11, wherein the length and width of a directional cell control the angular spread of the directional beam of the directional cell. The method of claim 11, wherein fabricating a directional backlight comprises fabricating a waveguide having a plurality of geometrically distinct regions, each region having a plurality of segments and A single directional pixel. A waveguide comprising: a plurality of geometrically distinct regions, each region having a plurality of segments; and a plurality of directional pixels disposed on the plurality of geometrically distinct regions for scattering an input planar beam into a plurality of directions A beam of light, each directional beam having a direction and angular spread controlled by the properties of one of the plurality of directional pixels. The waveguide of claim 15 wherein the plurality of segments comprise an angular section disposed between the two horizontally oriented segments.