JP2019148706A - Screen and display device - Google Patents

Abstract

An image display device capable of sufficiently reducing speckle and displaying a high-contrast image. A screen includes a control layer containing a plurality of particles or a liquid, electrodes for applying a voltage to the control layer, and a first polarization layer stacked on the control layer. And a sheet member 40x having a plate 43. At least one of the movement and rotation of the plurality of particles 60 occurs inside the control layer 55x according to the voltage applied to the control layer 55x, or the liquid 69x moves inside the control layer 55x according to the voltage. [Selection diagram] FIG.

Description

  The present disclosure relates to a screen for displaying an image and a display device.

  For example, as disclosed in Patent Document 1, projectors using a coherent light source are widely used. As the coherent light, laser light oscillated from a laser light source is typically used. When the image light from the projector is formed by coherent light, speckle is observed on the screen irradiated with the image light. Speckle is recognized as a speckled pattern and degrades the display image quality.

JP 2008-310260 A

  Patent Document 1 proposes a speckle reduction screen using an electrophoretic phenomenon. In the screen of Patent Document 2, the reflectance changes according to the irradiation position of the image light irradiated by the laser scanning method. By controlling the reflectance of the portion not irradiated with image light to be low, reflection of ambient light such as outside light and illumination light is suppressed in the low reflectance region, and a high-contrast image can be displayed. However, in the screen disclosed in Patent Document 1, the reflectance only changes depending on the display ratio of white particles and black particles, and has no effect on speckles generated on the screen. That is, it is impossible to achieve both reduction in speckle and display of a high-contrast image.

  The present disclosure has been made in consideration of the above points, and provides a screen capable of sufficiently reducing speckles and displaying a high-contrast image by a method different from the conventional one. The purpose is to do.

The screen of the present disclosure is
A sheet member having a control layer containing a plurality of particles or liquid, an electrode used to apply a voltage to the control layer, and a first polarizing plate laminated on the control layer;
At least one of movement and rotation of the plurality of particles occurs in the control layer according to the voltage applied to the control layer, or the liquid moves inside the control layer according to the voltage. .

In the screen of the present disclosure,
The sheet member further includes a second polarizing plate laminated on the control layer,
The control layer is disposed between the first polarizing plate and the second polarizing plate,
The transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate may be non-parallel.

In the screen of the present disclosure,
The sheet member further includes a second polarizing plate laminated on the control layer,
The control layer is disposed between the first polarizing plate and the second polarizing plate,
The first polarizing plate and the second polarizing plate may have a crossed Nicols arrangement.

In the screen of the present disclosure,
The sheet member further includes a reflector laminated on the control layer, and a quarter-wave plate laminated on the control layer,
The control layer and the quarter wavelength plate may be disposed between the first polarizing plate and the reflecting plate.

In the screen of the present disclosure,
The control layer includes a plurality of the particles,
The plurality of particles may include a first portion and a second portion, each having a different relative dielectric constant.

In the screen of the present disclosure,
The control layer includes a plurality of the particles,
The plurality of particles may be composed of two types of the particles having polarities different from each other.

The display device of the present disclosure is
One of the screens mentioned above,
A projector that irradiates the screen with image light.

  In the display device according to the present disclosure, the projector may include a light source that emits coherent light.

  According to the present disclosure, speckle can be sufficiently reduced and a high-contrast image can be displayed.

FIG. 3 is a diagram illustrating an example of a schematic configuration of a display device. The figure explaining a laser scanning system. Sectional drawing which shows the cross-section of a screen. Enlarged view of the particles. The figure which shows an alternating voltage waveform. Sectional drawing of the screen using the particle | grains of a structure different from FIG. Sectional drawing of the screen using the particle | grains of a structure different from FIG. 3 and FIG. Sectional drawing of the screen using the particle | grains of a structure different from FIG.3, FIG.6 and FIG.7. The figure which shows the example in which both the 1st electrode and the 2nd electrode are formed in stripe form. (A)-(c) is a figure which shows the example in which particle | grains are contained in one or some cavity. The schematic diagram which shows an example of the screen of an electrophoresis system. The schematic diagram which shows the other example of the screen of an electrophoresis system. The figure which shows the example which arranges many micro container between two electrodes. The figure which shows the example which controls the movement of particle | grains for every cell part. The figure which shows a microcup structure. The figure which shows a powder movement system. The figure which shows an electrowetting system. The figure which shows the other example of schematic structure of a display apparatus. The figure which shows the further another example of schematic structure of a display apparatus. Sectional drawing of the reflection type screen which rotated the particle | grains of FIG. 8 90 degree | times.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  In one embodiment described below, the display device 10 includes a screen 40 and a projector 20 that irradiates the screen 40 with image light. The screen 40 includes a sheet member 40 x that diffuses image light, and thereby an image that can be observed by the observer 1 can be displayed on the screen 40. As described below, the display device 10 or the screen 40 according to the present embodiment is devised to reduce speckles and improve image contrast. As a specific configuration, the sheet member 40x is laminated on the control layer 55x including a plurality of particles 60 or a liquid 69x, electrodes 41 and 42 used for applying a voltage to the control layer 55x, and the control layer 55x. A first polarizing plate 43. The plurality of particles 60 or the liquid 69x can change the traveling direction of the image light. Further, at least one of movement and rotation of the plurality of particles 60 occurs in the control layer 55x according to the voltage applied to the control layer 55x, or the liquid 69x moves in the control layer 55x according to the voltage. To do.

  Hereinafter, the present embodiment will be described with reference to some specific examples. First, a specific example of the display device 10 and the screen 40 will be described with reference to FIGS.

  FIG. 1 is a diagram illustrating an example of a schematic configuration of the display device 10. The display device 10 of FIG. 1 further includes a power source 30 and a control device 35 in addition to the projector 20 and the screen 40 irradiated with image light from the projector 20. The power source 30 applies an AC voltage to the screen 40. The control device 35 controls the state of the screen 40 by adjusting the voltage applied from the power source 30. The control device 35 also controls the operation of the projector 20. As an example, the control device 35 can be configured by a general-purpose computer.

  The projector 20 functions as an image light generation device that generates image light. The projector 20 irradiates the screen 40 with the generated image light. In the illustrated example, the projector 20 includes a coherent light source 21 that oscillates coherent light, and a scanning device (not shown) that adjusts the optical path of the coherent light source 21. The coherent light source 21 is typically composed of a laser light source that oscillates laser light. The coherent light source 21 may include a plurality of coherent light sources that generate light in different wavelength ranges. The oscillated light is in a state where polarization components are aligned in the same direction. Note that the light source does not have to emit coherent light, and may emit non-coherent light such as LED light.

  In the illustrated example, the projector 20 irradiates the screen 40 with coherent light by a laser scanning method. As shown in FIG. 2, the projector 20 emits coherent light so as to scan the entire area on the screen 40. Scanning is performed at high speed. The projector 20 stops the emission of coherent light from the coherent light source 21 according to the image to be formed. That is, only the position on the screen 40 where an image is to be formed is irradiated with coherent light. As a result, an image is formed on the screen 40. The operation of the projector 20 is controlled by the control device 35.

  Next, the screen 40 will be described. FIG. 3 is a sectional view showing a sectional structure of the screen. In the illustrated example, the screen 40 is configured by a sheet member 40 x including a control layer 55 x and electrodes 41 and 42. In the illustrated example, the sheet member 40x includes a particle sheet 50 including a control layer 55x. In the illustrated example, the control layer 55 x is formed as a particle layer 55 including a plurality of particles 60. The electrodes 41 and 42 are electrically connected to the power source 30. In the illustrated example, the first electrode 41 extends in a planar shape on one main surface of the particle layer 55 forming the control layer 55x, and on the other main surface of the particle layer 55 forming the control layer 55x, The second electrode 42 extends in a planar shape.

  Further, the sheet member 40x forming the screen 40 includes a first polarizing plate 43 laminated on the control layer 55x, as shown in FIG. The first polarizing plate 43 may be directly laminated in contact with the control layer 55x, or another member exists between the first polarizing plate 43 and the control layer 55x, and indirectly to the control layer 55x. May be laminated. In the example shown in FIG. 1, the first electrode 41 is provided between the first polarizing plate 43 and the control layer 55x. Further, as shown in FIG. 1, the sheet member 40 x forming the screen 40 includes a first cover layer 46 that covers the first electrode 41 and the first polarizing plate 43 and forms one outermost surface of the screen 40, and a second cover layer 46. A second cover layer 47 that covers the electrode 42 and forms the other outermost surface of the screen 40.

  The screen 40 in FIG. 1 constitutes a transmissive screen. The projector 20 emits image light from the side opposite to the display side surface 40 a, that is, from the back surface of the screen 40. The image light passes through the first cover layer 46, the first polarizing plate 43, and the first electrode 41 of the screen 40, and then diffuses in the control layer 55x and passes through the second electrode 42 and the second cover layer 47. As a result, the observer 1 positioned facing the display side surface 40a of the screen 40 can observe the image. However, as will be described later, the screen 40 may be formed as a reflective screen.

  The first electrode 41, the second electrode 42, the first cover layer 46, and the second cover layer 47 through which the image light is transmitted are transparent. The first electrode 41, the second electrode 42, the first cover layer 46, and the second cover layer 47 each preferably have a transmittance in the visible light region of 80% or more, and more preferably 84% or more. . In addition, visible light transmittance | permeability in each wavelength when it measures in the range of measurement wavelength 380nm -780nm using a spectrophotometer (Shimadzu Corporation "UV-3100PC", JISK0115 conformity product). It is specified as the average value of transmittance.

  As the conductive material forming the first electrode 41 and the second electrode 42, ITO (Indium Tin Oxide), InZnO (Indium Zinc Oxide), Ag nanowire, carbon nanotube, or the like may be used. it can.

  The first polarizing plate 43 decomposes the incident light into two orthogonally polarized components (p-polarized component and s-polarized component) and vibrates in one direction (direction parallel to the transmission axis) (for example, It has a function of transmitting a p-polarized component) and absorbing a linearly polarized component (for example, an s-polarized component) that vibrates in the other direction orthogonal to the one direction (direction parallel to the absorption axis). That is, the first polarizing plate 43 has a linearly polarized light separating function and transmits only light of a specific linearly polarized light component. In the present embodiment, the polarization component transmitted by the first polarizing plate 43 is the same as the polarization component of the image light oscillated from the light source 21.

  The first cover layer 46 is a layer for protecting the first electrode 41 and the control layer 55x, and the second cover layer 47 is a layer for protecting the second electrode 42 and the control layer 55x. The first cover layer 46 and the second cover layer 47 can be formed from a transparent resin, for example, polyethylene terephthalate having excellent stability, polycarbonate, cycloolefin polymer, or the like.

  Further, the second cover layer 47 may have retardation. Generally, when light having only a polarization component in a specific direction is transmitted through a member having retardation, the visible light transmittance is changed according to the wavelength of the transmitted light. The change in visible light transmittance increases as the retardation increases. If there is variation in retardation at each position of the member, the transmittance of light of different wavelengths at each position increases, so the light emitted from each position becomes light of different wavelengths and the color varies, resulting in rainbow unevenness. As visible. In the present embodiment, the light incident on the second cover layer 47 is transmitted through only the polarized light component in a specific direction by the first polarizing plate 43 and is not subjected to the diffusion action of the control layer 55x described later. In this state, linearly polarized light having only a polarized light component in a specific direction is obtained. Therefore, rainbow unevenness may occur due to the retardation of the second cover layer 47. Since rainbow unevenness may interfere with display of an intended image by mixing with image light, it is desirable to make rainbow unevenness inconspicuous.

  The smaller the retardation of a member through which light having only a polarization component in a specific direction is transmitted, the smaller the variation in visible light transmittance for each wavelength with respect to the variation in retardation. That is, if the retardation is sufficiently small, the visible light transmittance for each wavelength hardly changes even if the retardation varies. Therefore, when the retardation is sufficiently small, rainbow unevenness that can be visually confirmed does not occur. In the present embodiment, when the retardation of the second cover layer 47 is 10 nm or less, the variation in visible light transmittance for each wavelength according to the retardation is sufficiently small, and the rainbow unevenness is not effectively noticeable. Can be made.

  Or if the retardation of the member which the light which has only the polarization component of a specific direction permeate | transmits becomes large, the fluctuation | variation of the visible light transmittance for every wavelength with respect to the fluctuation | variation of retardation will become large. Therefore, when retardation increases, even if there is variation in retardation, light of a plurality of wavelengths is easily transmitted, and thus the transmitted light is easily mixed and visually recognized. That is, if the retardation is sufficiently large, light of a plurality of wavelengths is mixed and observed even if the retardation varies. For this reason, the change in the color of the transmitted light is hardly visually recognized. In the present embodiment, when the retardation of the second cover layer 47 is 3000 [nm] or more, the variation in visible light transmittance for each wavelength according to the retardation becomes large, and the rainbow unevenness is effectively inconspicuous. Can do.

  Examples of the transparent material having a small retardation include COP (cycloolefin polymer) and glass, and examples of the transparent material having a large retardation include SRF (Super Retardation Film) and PET (polyethylene terephthalate).

The retardation means a refractive index (n _x ) and a slow axis in a direction in which the refractive index is large (slow axis direction) at each position in the surface of the member measured using light having a measurement wavelength of 548.2 nm. refractive index in the direction (fast axis direction) perpendicular to the direction difference between the _{(n y)} and _(n x -n _y), the thickness of the member (d) and the product _{(d × (n x -n y} ) ) And is expressed in units of length (nm).

  Instead of providing the first polarizing plate 43, the first cover layer 46 may have a function of transmitting only one polarization component of the incident light.

  Next, the particle sheet 50 will be described. As shown in FIG. 3, the particle sheet 50 includes a pair of base materials 51, 52 and a control layer 55 x provided between the pair of base materials 51, 52. The first base material 51 supports the first electrode 41, and the second base material 52 supports the second electrode 42. The control layer 55 x is a particle layer 55 including a plurality of particles 60. The particle layer 55 constituting the control layer 55 x is sealed between the first base material 51 and the second base material 52. The first base material 51 and the second base material 52 are materials having a strength capable of sealing the particle layer 55 and functioning as a support for the electrodes 41 and 42 and the particle layer 55, for example, polyethylene terephthalate resin. It can be composed of a film. In the illustrated embodiment, the screen 40 is configured as a transmissive screen, and image light is transmitted through the first base material 51 and the second base material 52. Therefore, the first base material 51 and the second base material 52 are transparent, and have the same visible light transmittance as the first electrode 41, the second electrode 42, the first cover layer 46, and the second cover layer 47. It is preferable to have.

  Next, the particle layer 55 constituting the control layer 55x will be described. As well shown in FIG. 3, the particle layer 55 includes a large number of particles 60, a holding unit 56 that holds the particles 60, and a solvent 57 that swells the holding unit 56. The holding unit 56 holds the particles 60 in an operable manner. In the illustrated example, the holding portion 56 has a large number of cavities 56a, and the particles 60 are accommodated in the cavities 56a. The inner dimension of each cavity 56a is larger than the outer dimension of the particle 60 in the cavity 56a. Therefore, the particles 60 can operate in the cavity 56a. In the cavity 56 a, the space between the holding unit 56 and the particles 60 is filled with the solvent 57. According to the holding part 56 swollen by the solvent 57, the smooth operation of the particles 60 can be ensured stably. Hereinafter, the holding unit 56, the solvent 57, and the particles 60 will be described in order.

  First, the holding part 56 and the solvent 57 will be described. The solvent 57 is used for smooth operation of the particles 60. The solvent 57 is held in the cavity 56a as the holding portion 56 swells. The solvent 57 is preferably of low polarity so as not to prevent the particles 60 from operating in response to an electric field. As the low-polarity solvent 57, various materials that facilitate the operation of the particles 60 can be used. Examples of the solvent 57 include dimethyl silicone oil, isoparaffinic solvents, and linear alkanes such as linear paraffinic solvents, dodecane, and tridecane.

  Next, the holding | maintenance part 56 may be comprised using the elastomer sheet | seat which consists of an elastomer material as an example. The holding portion 56 as an elastomer sheet can swell the solvent 57 described above. Examples of the material for the elastomer sheet include silicone resin, (microcrosslinked) acrylic resin, (microcrosslinked) styrene resin, and polyolefin resin.

  In the illustrated example, the cavities 56 a are distributed at a high density in the plane direction of the screen 40 in the holding portion 56. The cavities 56 a are also distributed in the normal direction nd of the screen 40. In the illustrated example, three groups of cavities 56 a spreading in a plane are arranged in the thickness direction of the screen 40.

  Next, the particle 60 will be described. The particles 60 have a function of changing the traveling direction of image light emitted from the projector 20. In the illustrated example, the particle 60 has a function of diffusing image light. As will be described later, the screen 40 may be formed as a reflection type, and in application to the reflection type screen, the particles 60 of the control layer 55x may have a function of diffusing and reflecting image light.

  The particle 60 includes a first portion 61 and a second portion 62 having different relative dielectric constants. Therefore, when the particle 60 is placed in an electric field, an electron dipole moment is generated in the particle 60. At this time, the particle 60 moves toward a position where the vector of the dipole moment is opposite to the vector of the electric field. Therefore, when a voltage is applied between the first electrode 41 and the second electrode 42 and an electric field is generated in the control layer 55x located between the first electrode 41 and the second electrode 42, the particles 60 are It operates in the cavity 56a so as to assume a stable posture, that is, a stable position and orientation with respect to the electric field. The screen 40 changes its diffusion wavefront in accordance with the operation of the particle 60 having a light diffusion function.

  The particles 60 including the first portion 61 and the second portion 62 having different relative dielectric constants can be manufactured by various methods including known techniques. For example, organic or inorganic spherical particles are arranged in a single layer using an adhesive tape or the like, and a positively or negatively charged resin component layer or inorganic layer different from the spherical particles is deposited on a hemispherical surface (evaporation method, for example, 56-67887), a method using a rotating disk (for example, JP-A-6-226875), two kinds of droplets having different relative dielectric constants are brought into contact with each other in the air using a spray method or an ink jet method. It can be manufactured using a method for forming droplets (for example, JP-A-2003-140204) and a microchannel manufacturing method proposed in JP 2004-197083A.

  FIG. 4 is an enlarged view of the particle 60. The particle 60 has a spherical shape, and the first portion 61 and the second portion 62 are each hemispherical. The first portion 61 of the particle 60 has a first main portion 66a and a first diffusion component 66b dispersed in the first main portion 66a. Similarly, the second portion 62 has a second main portion 67a and a second diffusion component 67b dispersed in the second main portion 67a. Therefore, the spherical particles 60 can exhibit a diffusion function with respect to light traveling inside the first portion 61 and light traveling inside the second portion 62. Here, the diffusing components 66b and 67b are components that can act on the light traveling in the particle 60 to change the traveling direction of the light by refraction or the like. Such a light diffusion function (light scattering function) of the diffusion components 66b and 67b includes, for example, the diffusion components 66b and 67b made of a material having a refractive index different from that of the material forming the main portions 66a and 67a of the particle 60. It can be given. Examples of the diffusion components 66b and 67b having a refractive index different from that of the material forming the main portions 66a and 67a include resin beads, glass beads, metal compounds, a porous substance containing gas, and simple bubbles. The particles 60 are preferably transparent.

  The particle layer 55, the particle sheet 50, and the screen 40 forming the control layer 55x can be manufactured as follows as an example.

  The particle layer 55 can be manufactured by a known manufacturing method. That is, first, an ink in which the particles 60 are dispersed in the polymerizable silicone rubber is prepared. Next, the ink is stretched with a coater or the like, and further polymerized by heating or the like to form a sheet. By the above procedure, the holding part 56 holding the particles 60 is obtained. Next, the holding part 56 is immersed in a solvent 57 such as silicone oil for a certain period. As the holding portion 56 swells, a gap filled with the solvent 57 is formed between the holding portion 56 made of silicone rubber and the particles 60. As a result, a cavity 56a containing the solvent 57 and the particles 60 is defined. The particle layer 55 can be manufactured as described above.

  Next, the screen 40 can be manufactured using the particle layer 55 by the manufacturing method disclosed in JP2011-112792A. First, the particle layer 55 is covered with a pair of base materials 51 and 52, and the particle layer 55 is sealed using a laminate or an adhesive. Thereby, the particle sheet 50 is produced. Next, the screen 40 is obtained by providing the first electrode 41 and the second electrode 42 on the particle sheet 50 and further laminating the first polarizing plate 43, the first cover layer 46 and the second cover layer 47. .

  Next, the operation when displaying an image using the display device 10 will be described.

  First, under the control of the control device 35, the coherent light source 21 of the projector 20 oscillates coherent light. The light from the projector 20 is irradiated on the screen 40 after the optical path is adjusted by a scanning device (not shown). The polarization component of the oscillated light is the same as the linear polarization component in the direction that the first polarizing plate 43 transmits. As shown in FIG. 2, a scanning device (not shown) adjusts the optical path of the light so that the screen 40 scans the light. However, the emission of coherent light by the coherent light source 21 is controlled by the control device 35. The control device 35 stops the emission of the coherent light from the coherent light source 21 corresponding to the image to be displayed on the screen 40. The operation of the scanning device included in the projector 20 is so fast that it cannot be disassembled by human eyes. Therefore, the observer 1 observes simultaneously the light irradiated to each position on the screen 40 irradiated at intervals.

  The light irradiated on the screen 40 passes through the first cover layer 46, the first polarizing plate 43, and the first electrode 41, and reaches the control layer 55x. Irradiated light has only a polarization component in the same direction as the polarization component transmitted by the first polarizing plate 43, and thus is transmitted without being absorbed by the first polarizing plate 43. This light is diffused by the particles 60 of the particle layer 55 forming the control layer 55x, and is emitted toward various directions on the viewer 1 side of the screen 40. As the light is diffused, the polarization state of the light is disturbed, and it has polarization components in various directions. Thereafter, the emitted light passes through the second electrode 42 and the second cover layer 47. As a result, an image corresponding to the area irradiated with the coherent light on the screen 40 can be observed.

  The coherent light source 21 may include a plurality of light sources that emit coherent light in different wavelength ranges. In this case, the control device 35 controls the light source corresponding to the light in each wavelength region independently from the other light sources. As a result, a color image can be displayed on the screen 40. In this case, light from each light source is irradiated in a state where the polarization components are aligned in the same direction as the direction of transmission without being absorbed by the first polarizing plate 43.

  By the way, in the conventional screen, since ambient light such as external light and illumination light incident on the screen is transmitted without distinction from the image light, the portion irradiated with the image light and the image light are not irradiated. The difference in brightness with the part becomes small. For this reason, in order to realize display of a high-contrast image on a conventional screen, the influence of ambient light such as outside light and illumination light is suppressed by darkening the room where the screen 40 is installed. It was.

  On the other hand, the screen 40 in the present embodiment has a first polarizing plate 43. As described above, the first polarizing plate 43 transmits only the polarization component in a specific direction of the incident light. Ambient light is composed of light having various polarization components. Therefore, more specifically, a part of the ambient light is absorbed by the first polarizing plate 43 and does not pass through half of the ambient light. On the other hand, the image light is oscillated so as to have the same polarization component as the polarization component transmitted by the first polarizing plate 43. Therefore, the image light is transmitted without being absorbed by the first polarizing plate 43. That is, the ambient light is less likely to pass through the screen 40 than the image light, and the difference in brightness between the image light that passes through the screen 40 and the ambient light is increased. Thereby, it becomes possible to reduce the influence of environmental light on image light, and a high-contrast image can be displayed even in a bright environment.

  In addition, when an image is formed on a screen using coherent light, speckles with a speckled pattern are observed. One cause of speckle is thought to be that coherent light typified by laser light causes an interference pattern on the optical sensor surface (on the retina in the case of humans) after diffusing on the screen. In particular, when the screen is irradiated with coherent light by laser scanning, the coherent light is incident on each position on the screen from a certain incident direction. Therefore, when laser scanning is used, the speckle wavefront generated at each point on the screen is stationary unless the screen operates, and when the speckle pattern is visually recognized by the observer together with the image, the image quality of the displayed image is significantly degraded. It will be.

  On the other hand, the screen 40 of the display device 10 according to the present embodiment changes the diffusion wavefront with time. If the diffusion wavefront on the screen 40 changes, the speckle pattern on the screen 40 changes over time. Then, when the change with time of the diffusion wavefront is made sufficiently fast, the speckle patterns are overlapped and averaged, and are observed by the observer. Thereby, speckles can be made inconspicuous.

  The illustrated screen 40 has a pair of electrodes 41 and 42. The pair of electrodes 41 and 42 are electrically connected to the power source 30. The power source 30 can apply a voltage to the pair of electrodes 41 and 42. When a voltage is applied between the pair of electrodes 41, 42, an electric field is formed in the control layer 55 x located between the pair of electrodes 41, 42. In the particle layer 55 constituting the control layer 55x, particles 60 having a plurality of portions 61 and 62 having different relative dielectric constants are operably held. Since the particle 60 is originally charged or a dipole moment is generated at least when an electric field is formed in the particle layer 55, the particle 60 operates according to a vector of the formed electric field. When the particle 60 having a function of changing the traveling direction of light, for example, a diffusion function is operated, the diffusion characteristics of the screen 40 change with time. As a result, speckle can be made inconspicuous. The symbol “La” in FIG. 4 is image light emitted from the projector 20 to the screen 40, and the symbol “Lb” is image light diffused by the screen 40.

  It should be noted that the relative permittivity being different between the first portion 61 and the second portion 62 of the particle 60 is sufficient if the relative permittivity is different enough to exhibit the speckle reduction function. Therefore, whether or not the relative permittivity differs between the first portion 61 and the second portion 62 of the particle 60 depends on whether or not the operably held particle 60 can operate with a change in the electric field vector. Can be determined.

  Here, the principle that the particle 60 operates with respect to the holding unit 56 is to change the direction and position of the particle 60 so that the charge or dipole moment of the particle 60 has a stable positional relationship with respect to the electric field vector. That's it. Therefore, if a constant electric field is continuously applied to the particle layer 55, the operation of the particles 60 stops after a certain period. On the other hand, in order to make the speckle inconspicuous, it is necessary to continue the operation of the particles 60 with respect to the holding unit 56. Therefore, the power source 30 applies a voltage so that the electric field formed in the particle layer 55 changes with time. In the illustrated example, the power source 30 applies a voltage between the pair of electrodes 41 and 42 so as to invert the electric field vector generated in the control layer 55x. For example, in the example shown in FIG. 5, an AC voltage that repeats a voltage of X [V] and a voltage of −Y [V] is applied from the power source 30 to the pair of electrodes 41 and 42 of the screen 40.

  The particles 60 are accommodated in a cavity 56 a formed in the holding portion 56. The cavity 56a has a substantially spherical inner shape. Therefore, the particle 60 can be oscillated and rotated about the rotation axis ra extending in the direction orthogonal to the paper surface of FIG. However, depending on the size of the cavity 56a that accommodates the particle 60, the particle 60 not only repeatedly rotates but also translates. Further, the solvent 56 is filled in the cavity 56a. The solvent 57 facilitates the operation of the particles 60 with respect to the holding unit 56.

  By the way, the particle 60 is not limited to the structure including the substantially hemispherical first portion 61 and the second portion 62 as shown in FIG. Below, the 1st modification-the 3rd modification of particle 60 are explained in order. In these modified examples, the control layer 55x is formed by the particle layer 55 as in the above-described example, but the configuration of the particles 60 held in the holding unit 56 of the control layer 55x is different from the above-described example. .

(First Modification of Particle 60)
FIG. 6 is a cross-sectional view of a screen 40 using particles 60 having a structure different from that in FIG. Similar to the specific example described above, the screen 40 is configured by a sheet member 40 x including a control layer 55 x and electrodes 41 and 42, and the control layer 55 x is formed as a particle layer 55 including a plurality of particles 60. Yes. The particle 60 according to the first modification shown in FIG. 6 has a first portion 61 and a second portion 62 having different volumes. FIG. 6 shows an example in which the volume of the first portion 61 is larger than the volume of the second portion 62. In the case of FIG. 6, the second portion 62 has a shape close to a sphere or an elliptic sphere, and the surface of the second portion 62, that is, the interface with the first portion 61 is a convex surface. Note that the particle 60 is not necessarily an ideal sphere, and the second portion 62 may be slightly distorted from an ideal sphere or ellipsoid.

  The first portion 61 is a transparent member. Specific materials for the first portion 61 include, for example, silicone oil and a transparent resin member. The first portion 61 is ideally arranged on the viewer 1 side as shown in FIG. The light incident on the first portion 61 passes through the first portion 61 as it is and reaches the second portion 62. The second portion 62 has a relative dielectric constant different from that of the first portion 61 and has a light diffusion function. Further, the second portion 62 is configured with a refractive index lower than that of the first portion 61. The second portion 62 may include a diffusion component 62c that diffuses light. These diffusing components 62c act to change the traveling direction of the light traveling in the particle 60 by refraction or the like. Each of these components can be configured the same as the diffusion component described with reference to FIG.

  In addition, the surface of the second portion 62 has a convex shape. Therefore, when there is a difference in refractive index at the interface between the first portion 61 and the second portion 62, the light that has reached the second portion 62 from the first portion 61 is in a direction according to the convex shape of the surface of the second portion 62. Is diffused. From the above, the irradiation light from the projector 20 is diffused by the second portion 62 and an image is observed on the screen 40.

  In the state of FIG. 6, when a voltage is applied between the first and second electrodes 41 and 42, an electric field is generated between the first and second electrodes 41 and 42, and this electric field causes an electron bipolar in the particle 60. A child moment is generated. At this time, the particle 60 moves toward a position where the vector of the dipole moment is opposite to the vector of the electric field. By changing the voltage between the first electrode 41 and the second electrode 42, the posture of the particle 60 changes, and thereby the surface direction of the second portion 62 with respect to the surface direction of the particle layer 55 changes. Since the second portion 62 has a function of diffusing the light incident on the first portion 61, the diffusion characteristic of the light emitted from the second portion 62 also changes when the surface direction of the second portion 62 changes. . Thereby, speckle can be reduced also when the control layer 55x containing the particle | grains 60 shown by FIG. 6 is used.

(Second Modification of Particle 60)
FIG. 7 is a cross-sectional view of a screen 40 using particles 60 having a structure different from those in FIGS. 3 and 6. Similar to the embodiment and the first modification described above, the screen 40 is configured by the sheet member 40 x including the control layer 55 x and the electrodes 41 and 42, and the control layer 55 x is a particle including a plurality of particles 60. It is formed as a layer 55. A particle 60 according to the second modification shown in FIG. 7 includes a first portion 61 and a second portion 62 having a volume larger than that of the first portion 61. The material of the first portion 61 and the second portion 62 is the same as that of the first modification of the particle 60, the first portion 61 is a transparent member, and the second portion 62 has a light diffusion function. Further, the particle 60 is not necessarily an ideal sphere, and the first portion 61 may have a shape slightly distorted from an ideal sphere or ellipsoid.

  Also in the example shown in FIG. 7, when a voltage is applied between the electrodes 41 and 42 and an electric field is formed in the particle layer 55 forming the control layer 55x, a dipole moment is generated in the particle 60, and the dipole moment is generated. It moves toward the position where the vector of is directly opposite to the vector of the electric field. The particle 60 rotates by changing the voltage between the first electrode 41 and the second electrode 42. As the particle 60 rotates, the diffusion characteristics of the light emitted from the second portion 62 of the particle 60 change. Thereby, speckle can be reduced also when the control layer 55x containing the particle | grains 60 shown by FIG. 7 is used.

(Third Modification of Particle 60)
FIG. 8 is a cross-sectional view of a screen 40 using particles 60 having a structure different from those in FIGS. 3, 6, and 7. As in the above-described embodiment, the first modification, and the second modification, the screen 40 is configured by the sheet member 40x including the control layer 55x and the electrodes 41 and 42, and the control layer 55x includes a plurality of particles. 60 is formed as a particle layer 55 containing 60. 8 has a three-layer structure in which a first portion 61, a third portion 63, and a second portion 62 are arranged in this order, and the first portion 61 is on one side of the screen 40. Has been placed. The third portion 63 is in surface contact with the first portion 61 and controls incident light from the first portion 61 or the second portion 62. The second portion 62 is in surface contact with the second surface 63 b opposite to the first surface 63 a in surface contact with the first portion 61 of the third portion 63. The second portion 62 has a relative dielectric constant different from that of the first portion 61. As described above, the third portion 63 is sandwiched between the first portion 61 and the second portion 62, and the third portion 63 is in surface contact with the first portion 61 and the second portion 62.

  The first portion 61 and the second portion 62 are transparent members. The third portion 63 has a function of diffusing the light incident on the first portion 61. The third portion 63 is configured with a refractive index different from that of the first portion 61. The third portion 63 may include a diffusion component 63c that diffuses light. These diffusing components 63c act on the light traveling in the particles 60 by changing the direction of the light by refraction or the like. Such a light diffusion function (light scattering function) of the diffusion component 63c can be provided by the same configuration as the diffusion components 66b and 67b in the example shown in FIG. The shape of the particle 60 is typically a sphere, but is not necessarily an ideal sphere, and the shape of the first portion 61, the third portion 63, and the second portion 62 is also the shape of the particle 60. It changes according to.

  Also in the example shown in FIG. 8, when a voltage is applied between the electrodes 41 and 42 and an electric field is formed in the particle layer 55 forming the control layer 55x, a dipole moment is generated in the particle 60, and the dipole moment is generated. It moves toward the position where the vector of is directly opposite to the vector of the electric field. The particle 60 rotates by changing the voltage between the first electrode 41 and the second electrode 42. As the particle 60 rotates, the diffusion characteristics of the light emitted from the second portion 62 of the particle 60 change. Thereby, speckle can be reduced also when the control layer 55x containing the particle | grains 60 shown by FIG. 8 is used.

(Modification of electrodes 41 and 42)
In the screens of the first modification example and the second modification example described above, the example in which the first electrode 41 and the second electrode 42 are formed in a planar shape and arranged so as to sandwich the control layer 55x is shown. Not limited.

  In the example shown in FIG. 8, the configuration of the electrodes is also different from the above-described example. In the example shown in FIG. 8, electrodes are provided only on one side of the control layer 55x, for example, only on the opposite side of the control layer 55x from the observer. In the example shown in FIG. 8, the electrodes have first electrodes 41 and second electrodes 42 that are alternately arranged in a stripe pattern. By applying a voltage between the first electrode 41 and the second electrode 42, an electric field in the surface direction of the control layer 55x is formed. More specifically, in the present modification, an alternating voltage is applied between the adjacent first electrode 41 and second electrode 42 to form the control layer 55x in the surface direction rather than in the thickness direction of the control layer 55x. The electric field is switched periodically. Thereby, the particle | grains 60 located in the vicinity between the corresponding 1st electrode 41 and the 2nd electrode 42 can be rotated according to the frequency of alternating voltage.

  In the example described with reference to FIGS. 1 to 5, and in the first and second modified examples, one or more of the first electrode 41 and the second electrode 42 are striped as in the third modified example. You may make it form in a shape. For example, in the example of FIG. 9, both the first electrode 41 and the second electrode 42 are formed in a stripe shape. That is, the first electrode 41 has a plurality of linear electrode portions 41a extending linearly, and the plurality of linear electrode portions 41a are arranged in a direction orthogonal to the longitudinal direction. Similarly to the first electrode 41, the second electrode 42 also has a plurality of linear electrode portions 42a extending linearly, and the plurality of linear electrode portions 42a are arranged in a direction orthogonal to the longitudinal direction. . In the example shown in FIG. 9, the plurality of linear electrode portions 41a forming the first electrode 41 and the plurality of linear electrode portions 42a forming the second electrode 42 are both on the side opposite to the observer of the control layer 55x. It is arranged on the surface. The plurality of linear electrode portions 41a forming the first electrode 41 and the plurality of linear electrode portions 42a forming the second electrode 42 are alternately arranged along the same arrangement direction. Also by the first electrode 41 and the second electrode 42 shown in FIG. 9, an electric field can be formed in the control layer 55 x by applying a voltage from the power source 30.

(Modification of holding part 56)
As another modification, the cavity 56a included in each holding portion 56 in the particle layer 55 constituting the control layer 55x includes a single particle 60 and is separated from the other cavity 56a as shown in FIG. 10 (a). Alternatively, a plurality of cavities may be connected as shown in FIGS. 10B and 10C. FIG. 10B shows a holding portion 56 that includes single particles 60-1 and 60-2 in two connected cavities 56a1 and 56a2. The movable ranges of the particles 60-1 and 60-2 are restricted by the corresponding cavities 56a1 and 56a2. FIG. 10C shows the holding unit 56 including single particles 60-1, 60-2, and 60-3 in the three connected cavities 56a1, 56a2, and 56a3. The movable ranges of the particles 60-1, 60-2, and 60-3 are restricted by the corresponding cavities 56a1, 56a2, and 56a3. As described above, even when a plurality of cavities are connected, when the movable ranges of the plurality of particles are arranged without overlapping, the cavity of the holding unit 56 is configured to include a single particle. Can be considered.

  The inner diameter of the cavity is not limited as long as it is larger than the outer diameter of the encapsulated particles. For example, the inner diameter of the cavity may be set to be 1.1 to 1.3 times the outer diameter of the particles to be included.

(Other examples of control layer 55x)
In addition, each of the screens 40 described above operates by operating the particles 60 in the particle layer 55 forming the control layer 55x in a cavity provided corresponding to the particles 60 in accordance with an AC voltage applied to the electrode. Is not visible. As another modification, the speckles may not be visually recognized by moving the particles 60 in the particle layer 55 according to the AC voltage applied to the electrodes. Also in the following modifications, the screen 40 is configured by a sheet member 40x including a control layer 55x and electrodes 41 and 42. The control layer 55x includes a plurality of particles 60 or liquid 69x.

  FIG. 11A and FIG. 11B are schematic views showing an example of an electrophoretic screen 40. The screen 40 in FIG. 11A has a structure having a control layer 55x in which two types of particles 60 that migrate in a solvent are sealed between two opposing electrodes 41 and 42. The two types of particles 60 have different polarities. An AC voltage is applied between the two electrodes 41 and 42. By applying an alternating voltage, one particle 60 moves in the direction of one electrode, and the other particle 60 moves in the direction of the other electrode. When the polarity of the AC voltage applied between the two electrodes 41 and 42 is reversed, the two types of particles 60 move to the electrodes in the opposite directions, respectively. As the particles 60 move, the diffusion characteristics of the light diffused by the control layer 55x change. Thereby, speckle can be reduced.

  Instead of providing two kinds of particles 60 having different polarities as shown in FIG. 11A, a control layer 55x including particles 60 made of a dipole may be provided as shown in FIG. 11B. In this case, each time the voltage polarity of the AC voltage applied between the two electrodes 41 and 42 changes, each particle 60 vibrates. As a result, the diffusion characteristic of the control layer 55x in the screen 40 also changes, and speckles are not noticeable.

  11A and 11B, the particles 60 freely move between the two electrodes 41 and 42. However, when the area of the electrodes is large, some particles 60 remain in one place. There is a fear. For this reason, you may make it the pattern electrode which divided | segmented the electrode into the fine unit.

  11A and 11B allow a plurality of particles 60 to freely move between the two electrodes 41 and 42, but as shown in FIG. 11C, a micro-accommodation that accommodates two types of particles 60 having different polarities. A control layer 55 x including the body 64 may be provided, and a large number of the micro-accommodating bodies 64 may be disposed between the two electrodes 41 and 42. Moreover, the direction of the particle | grains 60 in the micro container 64 can be changed for every electrode by making one electrode into a pattern electrode. Thereby, the diffusion characteristics of the particles 60 change, and speckle can be reduced.

  As a modification of FIGS. 11A, 11B, and 11C, as shown in FIGS. 12A and 12B, a plurality of cell portions 53 are provided in the control layer 55x along the sheet surface of the screen 40, and each cell portion 53 is provided. By providing the electrode 41, the movement of the particles 60 may be controlled for each cell unit 53. In the partition wall structure as shown in FIG. 12A, each cell portion 53 is formed by two opposing base materials 51 and 52 and a partition wall portion 54. Such a structure can be formed relatively easily using photolithography and transfer techniques. In each cell part 53, the particle | grains 60 may be accommodated and the micro container 64 which accommodated the some particle | grains 60 like FIG. 11C may be accommodated.

  In the partition wall structure of FIG. 12B, irregularities are formed in the insulating layer 58 disposed on one electrode 42 by a molding process or the like, and the particles 60 and the solvent 57 are filled in the concave portions 59, and the substrate is formed thereon. The microcup array is manufactured by sealing with 51. For example, by arranging the electrode 41 for each microcup, the movement of the particles 60 inside the microcup can be controlled for each microcup.

  In addition, the screen 40 according to the present embodiment employs the powder movement that moves the plurality of particles 60 in the gas instead of adopting the electrophoretic control layer 55x that moves the plurality of particles 60 in the liquid medium. A control layer 55x may be employed. For example, as shown in FIG. 13, each cell part 53 of the partition structure of the control layer 55 x may be filled with a gas 77 and a plurality of particles 70. Here, the granular material 70 is a substance that exhibits fluidity without borrowing the force of gas or liquid. That is, the powder body 70 is an intermediate state having both characteristics of a particle and a liquid, and is a substance in a unique state that is not easily affected by gravity and exhibits high fluidity. Also in the case of FIG. 13, for example, by providing an electrode for each cell portion 53, the moving direction of the plurality of particles 60 can be varied for each cell, and speckle becomes inconspicuous.

  Further, the screen 40 may employ an electrowetting control layer 55x as shown in FIG. That is, the control layer 55x may include the liquid 69x instead of the particles 60. In the case of FIG. 14, each cell portion 53 of the partition structure of the control layer 55 x is filled with water 68 and oil droplets 69 as the liquid 69 x, and the oil droplets 69 are disposed on the dielectric layer 80. The oil droplet 69 moves inside the control layer 55x according to the applied voltage of the electrodes 41 and 42 corresponding to each cell portion 53, the contact angle of the oil droplet 69 with respect to the dielectric layer 80 changes, and the oil droplet 69 The surface area can be varied. As a result, the transmission characteristics of the screen 40 change and the speckles are hardly visually recognized.

  Each of the screens 40 described above is premised on using coherent light as the light source 21, but has an advantage that speckles are not noticeable on the screen 40 without taking measures against speckles on the light source 21 side. For this reason, it is assumed that each screen 40 mentioned above is used for various uses.

  If the desired size of the screen 40 is larger than the size of the sheet member 40x for the screen 40, a plurality of sheet members 40x may be connected to produce the screen 40 having an arbitrary size.

  As described above, the screen 40 according to the present embodiment includes the control layer 55x including the plurality of particles 60 or the liquid 69x, and the electrodes 41 that drive the plurality of particles 60 or the liquid 69x by applying a voltage to the control layer 55x. 42 and a first polarizing plate 43 laminated on the control layer 55x, and the movement and rotation of the plurality of particles 60 inside the control layer 55x according to the voltage applied to the control layer 55x. Or the liquid 69x moves inside the control layer 55x according to the voltage. According to such a screen 40, when a voltage is applied to the electrodes 41 and 42, the plurality of particles 60 or the liquid 69x are driven, and the diffusion characteristics of the screen 40 change with time. Therefore, speckle can be reduced by applying a voltage to the electrodes 41 and 42. Further, part of the ambient light, more specifically, half of the ambient light is absorbed by the first polarizing plate 43. On the other hand, by setting the polarization of the image light emitted from the light source as linearly polarized light that can be transmitted through the first polarizing plate, it is possible to effectively prevent the image light from being absorbed by the first polarizing plate. In this case, it is possible to effectively prevent the image from becoming dark. Therefore, the difference in brightness between the image light and the ambient light is increased, and a high-contrast image can be displayed on the screen 40. That is, speckles can be sufficiently reduced on the screen 40 and a high-contrast image can be displayed.

  Note that various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above-described embodiment are used for parts that can be configured in the same manner as in the above-described embodiment, and overlapping Description to be omitted is omitted.

  In the embodiment described above, the screen 40 has only one polarizing plate. However, as shown in FIG. 15, the screen 40 may have two polarizing plates. That is, the sheet member 40x included in the screen 40 further includes a second polarizing plate 44 laminated on the control layer 55x, and the control layer 55x is disposed between the first polarizing plate 43 and the second polarizing plate 44. It may be. In this case, the second polarizing plate 44 may be disposed between the second cover layer 47 and the particle sheet 50 including the control layer 55x.

  When it has the 2nd polarizing plate 44, the 1st polarizing plate 43 and the 2nd polarizing plate 44 are arrange | positioned so that a mutual transmission axis may become non-parallel. In other words, the first polarizing plate 43 and the second polarizing plate 44 are arranged so that their absorption axes are non-parallel. As a typical example, the first polarizing plate 43 and the second polarizing plate 44 have a crossed Nicols arrangement. Crossed Nicol means that the transmission axes of two polarizing plates are arranged so as to be orthogonal to each other. When the first polarizing plate 43 and the second polarizing plate 44 are arranged so that the transmission axis of the first polarizing plate 43 and the transmission axis of the second polarizing plate 44 are non-parallel, the first polarizing plate 43 is Only part of the transmitted light can pass through the second polarizing plate 44. When the first polarizing plate 43 and the second polarizing plate 44 are arranged in a crossed Nicol arrangement, the first polarizing plate 43 does not change in the polarization state between the first polarizing plate 43 and the second polarizing plate 44. The light transmitted through is absorbed by the second polarizing plate 44 and does not pass through the second polarizing plate 44. Since the polarization state of the image light that has not been diffused by the control layer 55x is not disturbed, it cannot pass through the second polarizing plate 44 and is not observed by the observer as image light. On the other hand, the image light diffused by the control layer 55 x is disturbed in the polarization state, and a part of the light can be transmitted through the second polarizing plate 44.

  The image light that has not been diffused by the control layer 55x does not contribute to the temporal change of the speckle pattern described above. That is, the image light that has not been diffused by the control layer 55x does not contribute to making the speckle inconspicuous. On the contrary, the image light is emitted in a fixed emission direction, which may cause speckle. Therefore, from the viewpoint of making speckles inconspicuous, it is preferable that image light that has not been diffused by the control layer 55x is not observed by an observer. By absorbing the image light that has not been diffused by the control layer 55x by the second polarizing plate 44, only the light diffused by the control layer 55x can be emitted from the screen 40. Therefore, the speckle can be made inconspicuous by not emitting the image light that can make the speckle stand out.

  Instead of providing the second polarizing plate 44, the second cover layer 47 may have a function of transmitting only one polarization component of incident light.

  In the above-described embodiment, an example in which the screen 40 is configured as a transmissive screen has been described. However, the present invention is not limited to this example. As illustrated in FIG. 16, the screen 40 is configured as a reflective screen. May be. In this case, the light source 21 of the projector 20 emits image light from the display side surface 40a side. In this case, the second electrode 42 may not be transparent, and may be formed of a metal such as aluminum or copper. Furthermore, the second cover layer 47 and the second base material 52 may not be transparent.

  When the screen 40 is configured as a reflection type screen, the sheet member 40x included in the screen 40 includes a quarter-wave plate 48 laminated on the control layer 55x, and a reflection plate 49 laminated on the control layer 55x. Furthermore, you may have. In the example shown in FIG. 16, a quarter-wave plate 48 is disposed between the reflector plate 49 and the control layer 55x. However, the control layer 55 x may be disposed between the reflection plate 49 and the quarter wavelength plate 48. Here, the quarter wavelength plate 48 is an optical element that applies phase modulation to incident light. The quarter-wave plate 48 generally causes phase modulation for a quarter wavelength in light of a specific wavelength included in incident light. Therefore, the quarter-wave plate 48 can change linearly polarized light into circularly polarized light for light of a specific wavelength included in incident light, and vice versa. On the other hand, the reflection plate 49 is a member that reflects light.

  In such a reflective screen, the image light irradiated from the display side surface 40a is oscillated so as to have only the same polarization component as the polarization component transmitted by the first polarizing plate 43. Therefore, the image light passes through the first polarizing plate 43 without being absorbed by the first polarizing plate 43. On the other hand, a part of the environmental light is more specifically absorbed by the first polarizing plate 43 by half of the environmental light. As a result, the influence of ambient light can be greatly reduced as in the above-described embodiment.

  Part of the light transmitted through the first polarizing plate 43 is diffused and reflected by the control layer 55x to disturb the polarization state, and part of the light is transmitted through the first polarizing plate 43 and emitted from the display side surface 40a. Observed. That is, the ambient light is less likely to pass through the screen 40 than the image light, and the difference in brightness between the image light and the ambient light is increased. Thereby, similarly to the above-described embodiment, it is possible to reduce the influence of the environmental light on the image light, and it is possible to display a high-contrast image even in a bright environment.

  On the other hand, another part of the image light is not diffusely reflected by the control layer 55x. Image light that has not been diffusely reflected by the control layer 55x does not contribute to the above-described change in the speckle pattern with time and may cause speckle, so it is preferable that the image light is not observed by an observer. The image light that has not been diffused by the control layer 55x passes through the quarter-wave plate 48, is reflected by the reflection plate 49, and then passes through the quarter-wave plate 48 again. The image light is linearly polarized light that vibrates in one direction. However, it passes through the quarter wavelength plate 48 once to become circularly polarized light, is reflected by the reflection plate 49, and passes through the quarter wavelength plate 48 again. Thus, the linearly polarized light vibrates in the other direction orthogonal to the one direction. That is, by passing through the quarter-wave plate 48 twice, the vibration direction of the linearly polarized light formed by the image light changes by 90 °. Even if this image light is transmitted through the control layer 55x again, all of the image light is absorbed by the first polarizing plate 43. That is, the image light that has not been diffusely reflected by the control layer 55 x is absorbed by the first polarizing plate 43. Therefore, only the light diffused by the control layer 55x can be emitted from the screen 40, and the speckle can be made inconspicuous by not emitting the image light that may cause speckle.

  Further, another part of the image light is transmitted through the control layer 55 x toward the reflection plate 49, and reflected by the reflection plate 49 and transmitted through the control layer 55 x again toward the first polarizing plate 43. At this time, the control layer 55x can be diffused and transmitted. As described above, when passing through the quarter-wave plate 48 twice, the vibration direction of the linearly polarized light formed by the image light changes by 90 ° and is absorbed by the first polarizing plate 43 unless the polarization state is disturbed. On the other hand, a part of the image light transmitted twice through the quarter wavelength plate 48 is diffused and transmitted through the control layer 55x, is transmitted through the first polarizing plate 43 and is emitted from the display side surface 40a, and is observed by the observer. Is done. That is, image light that can contribute to reduction of speckles by diffusion can form an image effectively.

  The display device 10 including the screen 40 described above may be used by being incorporated in, for example, furniture or electrical appliances.

  Aspects of the present disclosure are not limited to the individual embodiments described above, but include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the contents described above. That is, various additions, changes, and partial deletions can be made without departing from the concept and spirit of the present disclosure derived from the contents defined in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Display apparatus 20 Projector 21 Light source 30 Power source 35 Control apparatus 40 Screen 40x Sheet member 40a Display side surface 41 1st electrode 42 2nd electrode 43 1st polarizing plate 44 2nd polarizing plate 46 1st cover layer 47 2nd cover layer 48 1/4 wavelength plate 49 Reflecting plate 50 Particle sheet 51 First substrate 52 Second substrate 55 Particle layer 55x Control layer 56 Holding portion 56a Cavity 57 Solvent 60 Particle 61 First portion 62 Second portion 66a First main portion 66b First diffusion component 67a Second main portion 67b Second diffusion component 69 Oil droplet 69x Liquid ra Rotation axis

Claims (7)

A sheet member having a control layer containing a plurality of particles or liquid, an electrode used to apply a voltage to the control layer, and a first polarizing plate laminated on the control layer;
Depending on the voltage applied to the control layer, at least one of movement and rotation of the plurality of particles occurs inside the control layer, or the liquid moves inside the control layer according to the voltage. To the screen. The sheet member further includes a second polarizing plate laminated on the control layer,
The control layer is disposed between the first polarizing plate and the second polarizing plate,
The screen according to claim 1, wherein a transmission axis of the first polarizing plate and a transmission axis of the second polarizing plate are non-parallel. The sheet member further includes a reflector laminated on the control layer, and a quarter-wave plate laminated on the control layer,
The screen according to claim 1, wherein the control layer and the quarter-wave plate are disposed between the first polarizing plate and the reflecting plate. The control layer includes a plurality of the particles,
The screen according to claim 1, wherein each of the plurality of particles includes a first portion and a second portion having different relative dielectric constants. The control layer includes a plurality of the particles,
The screen according to any one of claims 1 to 3, wherein the plurality of particles are composed of two types of particles having polarities different from each other. A screen according to any one of claims 1 to 5,
And a projector that irradiates the screen with image light.   The display device according to claim 6, wherein the projector includes a light source that emits coherent light.

Images