WO2005116732A1 - Dispositif optique pour un ecran comprenant un guide d'onde a impedance croissante et procede de fabrication - Google Patents

Dispositif optique pour un ecran comprenant un guide d'onde a impedance croissante et procede de fabrication Download PDF

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Publication number
WO2005116732A1
WO2005116732A1 PCT/KR2005/000421 KR2005000421W WO2005116732A1 WO 2005116732 A1 WO2005116732 A1 WO 2005116732A1 KR 2005000421 W KR2005000421 W KR 2005000421W WO 2005116732 A1 WO2005116732 A1 WO 2005116732A1
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WO
WIPO (PCT)
Prior art keywords
light
waveguide
resin
optical device
coating
Prior art date
Application number
PCT/KR2005/000421
Other languages
English (en)
Inventor
Gyuhwan Hwang
Youngbin Yu
Hyunsoo Lee
Original Assignee
Sekonix Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020040039322A external-priority patent/KR100470324B1/ko
Priority claimed from KR1020040039320A external-priority patent/KR100450715B1/ko
Application filed by Sekonix Co., Ltd. filed Critical Sekonix Co., Ltd.
Publication of WO2005116732A1 publication Critical patent/WO2005116732A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/26—Reflecting filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/08—Catadioptric systems
    • G02B17/0856—Catadioptric systems comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/26—Reflecting filters
    • G02B5/265—Reflecting filters involving total internal reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133524—Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides

Definitions

  • the present invention relates to an optical device for a display and a method of fabricating the same. More particularly, the invention relates to an optical device for a display having a tapered waveguide and a method of fabricating such devices.
  • an optical device for a display such as a projection TV, a screen for rear- projection projectors, a TFT-LCD, a PDT TV, and a CRT monitor has a fine lens structure or a waveguide structure in order to broaden the viewing angle thereof.
  • the present invention relates to an optical device for a display having a waveguide structure and a method of manufacturing such devices.
  • US Patent No. 5,462,700 discloses a process for forming a tapered waveguide using ultraviolet rays. This patent process necessitates various precision control parameters.
  • the width of the opaque line 12, that form the lattice pattern of the photomask 19, determines the spacing c between the waveguides 20.
  • a thinner line 12 is better, but there is a limitation therein.
  • a large-sized plotter capable of printing a line of below 3mm does not exist, and even if such a plotter existed, limitations in their manufacturing speed and cost still exist.
  • a photomask formed of chromium lines on a glass has been used for waveguide production.
  • this type of photomask also leads to an increase in the cost of manufacturing such devices, due to the high fabrication cost of itself and a shortened service life, relative to any productivity gain.
  • FIG. 3 shows a conical waveguide disclosed in the above US patent.
  • Each waveguide 20a has a light input surface 22 and a light output surface 24.
  • Located between the light input surfaces 22 are numerous non-input surfaces 26, which do not allow the imaging light rays 25 to be incident into the waveguide 20a. As depicted in Fig. 4, these non-input surfaces 26 do not allow the imaging light rays 25 to be inputted into the waveguide 20a, and thus causing a light loss.
  • the conventional optical device for a display contains these non-input surfaces 26 and consequently comes to have a degraded light efficiency.
  • the photopolymerizable resin must be uniformly coated with precise thickness in order to obtain a waveguide of uniform height.
  • this process necessitates expensive precision coating equipment, which leads to a reduction in productivity and an increase in maintenance costs, and consequently an increase in product price.
  • the size of a waveguide relies upon the fineness of a photomask.
  • the pitch size which corresponds to the size of a waveguide, can be achieved up to the order of 70mm. This size is expected to become finer and finer, according to the trend of pursuing a higher level of image quality.
  • line width is an important factor in determining the width of between waveguides.
  • the loss of incident light increases proportionally.
  • a technique for minimizing line width is greatly needed.
  • the photomask is not in high demand and should be manufactured based on order requirements.
  • the service life thereof is relatively short, compared with the production quantity.
  • An alternative approach for manufacturing optical devices for displays is greatly needed.
  • Sunlight or surrounding illumination may be reflected on the front face of the optical device 10, so that the observed image may be relatively dark or blocked by means of unnecessary light rays.
  • the light- absorbing region 25 of Fig. 5 is structured in such a way that a black material is coated or filled in the area excepting the light-diverging region of the optical device 10, thereby absorbing the surrounding light rays.
  • the above-mentioned waveguide 20 employs light reflection on the interface between two mediums having different refraction indices.
  • the incident light rays are totally reflected, or partially reflected and partially passes through the interface, depending upon the magnitude of the incident angle.
  • 5,462,700 has a refraction index of 1.6 at maximum and the lower index resin filled in the surroundings is limited to around 1.3. Thus, a difference of about 0.3 in the refraction indices between the two mediums causes a difficulty and limitation in the design of a waveguide.
  • the screen for a projection TV is manufactured up to 61 inches and, in case of PDP, up to 80 inches.
  • the provision of a metallic coating on the front face thereof causes many difficulties and problems, in terms of quality, productivity, facility and the like.
  • An expensive facility is required for depositing a large screen in a short period of time. In terms of productivity related to mass production, the competitive force thereof is not comparable.
  • the light-absorbing region is formed of a resin having a low refraction index relative to the waveguide and dispersed with fine carbon black particles or a black colorant.
  • US Patent No. 5,462,700 employs the former method, and mentions that the carbon black particles must be controlled in such a manner as to avoid contact with the sidewall of the waveguide. This will be more detailed below, referring to Fig. 6.
  • Another object of the invention is to provide an optical device for a display capable of decreasing the light quantity absorbed into the light-absorbing region, to thereby enhance the light efficiency, as compared with the conventional ones.
  • a further object of the invention is to provide an optical device for a front- projection display having an improved light efficiency.
  • a further object of the invention is to provide a method of fabricating such optical devices.
  • an optical device for a display which includes tapered waveguides disposed at intervals and a light-absorbing region disposed between the waveguides and for absorbing external lights and reducing reflection, the tapered waveguide having a slant face for reflecting and diffusing incident lights and a light input surface and a light output surface formed at a front and rear end of the slant face.
  • the method of the invention comprises steps of: preparing a photomask having a plurality of opaque regions disposed at intervals and transparent regions between the opaque regions; coating a photopolymerizable resin on a front surface of the photomask; exposing a rear surface of the photomask to light rays such that the light-exposed portion of the photopolymerizable resin is polymerized to thereby form a surrounding region of waveguide; washing away the non-polymerized portion of the photopolymerizable resin to thereby form a space to be formed into a waveguide; fixedly disposing a material having a refraction index different from the surrounding region in the inner side of the sidewall of the space to thereby form a waveguide; releasing the photomask; and disposing a blackish material on the surface of the surrounding region in the light output surface side to thereby form the light- absorbing region.
  • a material having a refraction index larger than that of the surrounding region is fixedly disposed in the inner side of the sidewall of the space.
  • a material having a refraction index smaller than the surrounding region may be employed.
  • the critical angle for total reflection at an interface between two mediums is determined, depending on the difference in their refraction indices. In general, as the difference in the refraction indices increases, the critical angle becomes larger, i.e., the total reflection probability increases.
  • the opaque region of the photomask is preferred to have a dot-type or a line-type, but, in some cases, may be a line-type.
  • the photopolymerizable resin coating step may include steps of: placing a transparent support film on the photomask and coating the photopolymerizable resin on the transparent support film.
  • the waveguide forming step may include steps of: filling a resin having a refraction index larger than that of the surrounding region into the space and curing the resin filled in the space.
  • the waveguide is a cell-type, not a line-type.
  • the waveguide forming step may include a step of providing a coating for increasing reflection efficiency, such as a metallic coating, a total reflection coating, or the like.
  • the light-absorbing region forming step may include steps of: coating a photosensitive adhesive on the surface of the light output surface side, attaching light- absorbing particles of blackish color on the photosensitive adhesive, radiating light rays from the light input surface towards the light output surface such that a light- exposed portion of the photosensitive adhesive loses the adhesive force thereof; and releasing the light-absorbing particles from that portion of the adhesive that has lost the adhesive force thereof.
  • an optical device for a display including tapered waveguides disposed at intervals and a light-absorbing region disposed between the waveguides and for absorbing external lights and reducing reflection, the tapered waveguide having a slant face for reflecting and diffusing incident lights and a light input surface and a light output surface formed at a front and rear end of the slant face, wherein the light input surface of the waveguides are substantially integrated into a single surface.
  • This optical device for a display can be fabricated through the above-mentioned method.
  • an optical device for a front-projection display including tapered waveguides disposed at intervals and having a slant face for reflecting light rays, and a surrounding region disposed between the waveguides.
  • the optical device for a front-projection display comprises: a film having a plurality of opaque regions arranged at intervals and a transparent region between the opaque regions; a surrounding region formed of a photopolymerizable resin, which is coated on a front-surface of the film and cured; and a coating layer for increasing reflection rate such as a metallic coating, a total reflection coating and the like provided in the inner side of the sidewall of a space formed between the surrounding regions.
  • the opaque region is one of a circular shape, a rectangular shape, other polygonal point, and a line-shape, and the transparent regions on a same line of one direction are all connected.
  • an optical device for a front-projection display which includes tapered waveguides disposed at intervals and having a slant face for reflecting light rays, and a surrounding region disposed between the waveguides.
  • the method of the invention comprises steps of: preparing a film having a plurality of opaque regions arranged at intervals and a transparent region between the opaque regions; coating a photopolymerizable resin on a front-surface side of the film; exposing a rear surface of the film to light rays such that the light-exposed portion of the photopolymerizable resin is polymerized to thereby form a surrounding region of waveguide; washing away the non-polymerized portion of the photopolymerizable resin to thereby form a space to be formed into a waveguide; and providing a coating for increasing reflection efficiency in the inner side of the sidewall of the space, such as a metallic coating, a total reflection coating, to thereby form a waveguide.
  • the film preparing step may includes a step of preparing a film where the opaque region is one of a circular shape, a rectangular shape, other polygonal point, and a line- shape, and the transparent regions on a same line of one direction are all connected.
  • the method of fabricating an optical device for a display according to the invention has been made in order to improve the performance of an optical device for a display and the production efficiency thereof.
  • the surrounding area of the waveguide is formed first and thus precision control parameters can be minimized, thereby enabling to expect an improvement in the production efficiency and reduction in the manufacturing cost.
  • the photopolymerizable resin may be formed of at least one reactive monomer and a photoinitiator.
  • Examples for the monomer include methyl methacrylate, n-butyl acrylate, and the like, which are described in detail in US Patent No. 5,462,700.
  • photoinitiator examples include benzidimethyl ketal and the like, which can refer to US Patent No. 5,462,700.
  • an optical device for a display including tapered waveguides disposed at intervals and having a slant face for reflecting and diffusing incident light rays, and a light-absorbing region disposed between the waveguides and for absorbing external lights and reducing reflection.
  • the optical device comprises: a first resin filled and cured between the waveguides, the first resin having a refraction index smaller than that of the waveguide; a light transmissive adhesive coated on a narrower side surface of the waveguide, the light transmissive adhesive losing the adhesive force thereof when exposed to ultraviolet rays; light-absorbing particles of blackish color attached to the surface of the optical device through the light transmissive adhesive so as to absorb external lights and reduce reflection rate; and a light-absorbing particle-absent region in which the blackish light-absorbing particles are released by ultraviolet rays radiated through the waveguide from the opposite side of the coated light transmissive adhesive, the particle-absent region allowing light rays to pass from the opposite side of the coated light transmissive adhesive through the waveguide towards the front side thereof.
  • the first resin may include a thermoplastic resin such as glycidyl metacrylate, vinyl silicon or the like.
  • the light-absorbing particles of blackish color may include fine particles of black color such as carbon black, iron oxide, black spherical resin, and the like.
  • the above optical device may further comprise a resin-coating layer formed of a transparent resin coated on the light-absorbing particles of black color.
  • the light transmissive adhesive may include an acrylic or iso- vinyl photopolymerizable adhesive, which loses the adhesive force by photopolymerization.
  • an optical device for a display which includes tapered waveguides disposed at intervals and having a slant face for reflecting and diffusing incident light rays, and a light-absorbing region disposed between the waveguides and for absorbing external lights and reducing reflection.
  • the method of the invention comprises steps of: filing and curing a first resin between the waveguides, the first resin having a refraction index smaller than that of waveguide; coating a light transmissive adhesive on a narrower side surface of the waveguide, the light transmissive adhesive losing the adhesive force thereof when exposed to ultraviolet rays; attaching light-absorbing particles of black color on a surface of the coated light transmissive adhesive, the light- absorbing particles being to absorb external lights and reducing reflection; and releasing the light-absorbing particles placed on the waveguide from the light transmissive adhesive by radiating ultraviolet rays towards the coated light transmissive adhesive through the waveguide from the opposite side of the coated light transmissive adhesive.
  • the above method may further comprise steps of: coating a transparent resin on the attached light-absorbing particles of black color, and curing the coated transparent resin to stabilize the fixed light-absorbing particles.
  • the light transmissive adhesive coating step includes a step of coating an acrylic or iso-vinyl photopolymerizable adhesive.
  • the waveguide is structured so as to be separated from each other and disposed in a dot-pattern or a cell-pattern, and suitable for a tapered waveguide with its four lateral faces all inclined.
  • the waveguide structure of the invention can be applied to a waveguide with two lateral faces slanted and arranged linearly.
  • the tapered waveguide of the invention has a light input surface having a relatively larger area and a light output surface having a relatively smaller area, which are in parallel to each other.
  • the shape of the light input surface may take on all the polygonal shapes such as a square, a rectangle, and a rhombus, or a circle, or an oval.
  • the light output surface may be the same, or may have a different shape from the light input surface.
  • the sidewall of the waveguide has basically a plane shape, but may take on a curved surface.
  • the sidewall of the waveguide is inclined at a certain angle with respect to the input angle of the imaging light rays. Each of the waveguides may have a different inclination angle.
  • the optical devices of the invention having the above-described construction have an improved structure capable of enhancing the luminance of a screen.
  • the shape of the tapered waveguide and the surrounding area thereof are both improved such that loss in light quantity can be minimized, thereby increasing light efficiency.
  • the light-absorbing regions of the waveguide do not have a gap between them, thereby significantly reducing light loss.
  • the thickness of the photopolymerizable resin to be coated does not necessitate precise and uniform control, thereby simplifying the manufacturing process and reducing the cost of manufacturing.
  • an optical device for a front-projection display having a tapered waveguide can be easily fabricated.
  • the optical device according to the invention has an improved light efficiency, and thus can provide a product having an excellent luminance, as compared with the conventional ones, when using an identical light source.
  • an optical device having a stabilized light- absorbing region can be provided.
  • the present invention provides a simplified process for fabricating an optical device for a display, thus improving production efficiency.
  • the screen structure of a common-type lens projection TV is composed of a Fresnel lens and a lenticula lens.
  • the lenticula lens takes on a vertical line-pattern, which differs from a cell-pattern structure.
  • the open area is structured in vertical lines and thus external lights entered from the upper side thereof are reflected on the Fresnel lens.
  • a cell-pattern structure can be employed, instead of a line-pattern, thus reducing the above reflection phenomenon of input light.
  • the conventional line-type uses a diffusion plate at its front side to thereby form a vertical viewing angle.
  • the present invention employs a cell-type structure to thereby be able to form the vertical viewing angle on its own.
  • FIG. 1 is a plan view of a conventional photomask
  • FIG. 2 is a perspective view of a conventional waveguide fabricated using the photomask of Fig. 1 ;
  • FIG. 3 is a perspective view of another conventional waveguide for optical devices
  • FIG. 5 is a sectional view of an optical device for a display using tapered waveguides
  • Fig. 6 is a partial enlarged view of a light-absorbing region filled with carbon black particles
  • FIG. 7 is a schematic diagram showing the path of imaging light rays inputted inside the waveguide
  • Fig. 8 is a graph showing the relationship between the reflection rate and the input angle in two mediums having a difference of 0.6 in their refraction indices;
  • FIG. 9 is a diagram illustrating the path of imaging light rays depending upon the input angles thereof;
  • Fig. 10 illustrates a dot-pattern photomask used in a method of fabricating an optical device for a display according to the invention
  • FIG. 11 is a schematic diagram explaining a method of the invention, using the dot- pattern photomask of Fig. 10;
  • FIGs. 12 to 16 are schematic diagrams explaining a method of fabricating an optical device for a display according to the invention.
  • Fig. 18 is a flow chart explaining a method of fabricating an optical device for a display according to the invention.
  • FIGs. 19 to 22 show another example for the attachment of light-absorbing particles using a photosensitive adhesive
  • FIG. 23 illustrates a waveguide having another type of light input surface according to the invention.
  • Fig. 24 shows the input lights traveling through the input surface of Fig. 23;
  • FIGs. 25 and 26 are schematic diagrams explaining a method of fabricating an optical device for front-projection projectors according to the invention.
  • Fig. 27 is a schematic diagram showing the operation of the optical device for front- projection projectors in Figs. 25 and 26;
  • Fig. 28 illustrates a modified embodiment of Fig. 26. Best Mode for Carrying Out the Invention
  • imaging light rays are inputted into a waveguide 120 of an optical device for a display 100 and the input imaging light rays are reflected on the sidewall 122 of the waveguide 120. At this time, the imaging light rays are totally reflected on the sidewall 122 or pass through the sidewall 122, depending upon the input angle thereof. If the input angle of the imaging light rays is larger than the critical angle thereof (in the case of light ray 124a), the light rays are totally reflected or mostly reflected on the sidewall 22 of the waveguide 120.
  • the imaging light rays are partially total-reflected, and partially pass through the waveguide 120 and are absorbed in a light absorbing section 129, to thereby significantly decrease the reflection rate for the imaging light rays.
  • it In order to obtain an optical device for a display having a good optical efficiency, it must be designed such that the incident imaging light rays can perform a total reflection on the sidewall 122 of the waveguide 120.
  • Qc denotes a critical angle for total reflection
  • nw denotes a refraction index of waveguide
  • ns denotes an refraction index of surrounding medium.
  • Fig. 9 shows the light travelling path inside the waveguide in a case where the width of the light input surface is 40mm, the gradient of the waveguide sidewall is 4 degrees, the refraction index nw of the waveguide is 1.6 degrees, the refraction index ns of the surrounding medium is 1.3, and the light rays are incident at the range of from 0 to 10 degrees with respect to the axis H.
  • the input angle is 10 degrees (in the case of the light ray 126)
  • the input light ray partially passes through the waveguide 120 at its fourth reflection 127.
  • the length of the waveguide 120 is to be limited to 173mm, which corresponds to the fourth reflection point.
  • Fig. 10 illustrates a dot-pattern photomask used in a method of fabricating an optical device according to the invention.
  • the dot-pattern photomask 110 of Fig. 10 is composed of opaque regions 112 each formed of a square dot and transparent regions 114 disposed between the opaque regions 112.
  • the opaque region 112 has the same shape and size as the light output surface to be formed. As understood to those skilled in the art, the opaque region 112 may have a circular shape or other polygon shapes, instead of the square shape, depending on the design of the waveguide to be formed or the surroundings thereof.
  • the photomask 110 includes a transparent region 114 passing light rays and an opaque region 112 not passing light rays.
  • a photopolymerizable resin 130 with a certain desired thickness is coated on the photomask of Fig. 10, and thereafter, collimated ultraviolet rays are radiated on the opposite side thereto.
  • only the resin 130 placed on the transparent region 114 is photo-polymerized to thereby be cured.
  • the cured portion becomes the surrounding region 132 of the waveguide 120.
  • the resin to be coated takes on an almost liquid phase.
  • the portion near the photomask 110 is polymerized instantaneously into a solid form and a refraction index difference occurs in-between with the remaining liquid phase resin.
  • the shape of the cured portion changes with time.
  • the degree of cure can be easily adjusted by controlling the composition of the photo-polymerization resin, the wavelength of actinic ultraviolet rays, the exposure time, and the like.
  • the degree of cure for each resin composition with the time of exposure and the wavelength of ultraviolet rays can be easily determined through repetitive experiments by those having ordinary skills in the art.
  • a dot-pattern photomask 110 having dot-type opaque regions 112 is prepared, as shown in Fig. 10 (step 201).
  • the shape and size of the dot-type opaque region 112 is made to match those of the light output surface of the waveguide to be formed in the optical device.
  • a photopolymerizable resin 130 is coated on the dot-pattern photomask 110, which is exposed to ultraviolet rays 30. More specifically, a transparent support film 140 is placed on the dot-pattern photomask 110 (step 202), and then the photopolymerizable resin 130 having a certain thickness is coated on the transparent support film 140 (step 203). Collimated ultraviolet rays 30 are then radiated from the opposite side to the photopolymerizable resin 130, thereby forming the surrounding region 132 of the waveguide as shown in Fig. 13. The thickness of the photopolymerizable resin 130 is preferably uniform.
  • the support film 140 may be removed after the final procedures, or may remain to thereby protect the resultant optical device.
  • the support film 140 coated with a protective coating or a non- reflective coating may be used.
  • the coated side 142 of the support film 140 comes to be contacted with the dot-pattern photomask 110.
  • the length of a waveguide is adjusted by controlling the thickness of the photopolymerizable resin, and thus precision control of the resin thickness is of great importance.
  • the photopoly- merizable resin may be coated adequately thicker than the desired length of the waveguide 120, without necessity of precision control of the thickness thereof.
  • the length of the surrounding region 132 that becomes the length of the waveguide 120 is adjusted through the composition of the photopolymerizable resin 130, the exposure time and intensity of the ultraviolet rays, or the like. An appropriate exposure time and intensity of the ultraviolet rays for a photopolymerizable resin can be determined through repetitive experiments.
  • the photopolymerizable resin 130 exposed to ultraviolet rays is photo-polymerized and cured, and the cured portion comes to form the surrounding region 132 of the waveguide (step 204).
  • the unexposed, i.e., uncured photopolymerizable resin 130 of liquidus phase is washed away to be removed.
  • the surrounding region 132 has a triangular cross-section or a pointed tip 133.
  • a space 122a in which a waveguide is to be formed (step 205) is created in the places where the uncured photopolymerizable resin 130 is removed.
  • the shapes of the formed space 122a and the surrounding region 132 are illustrated in Fig. 17.
  • the portion exposed to ultraviolet rays is formed into the surrounding region 132 of the waveguide.
  • the thickness of the coated photopolymerizable resin 130 does not need to be controlled with precision and accuracy, so that the process facility can be simplified and the process speed can be improved.
  • the structure of the waveguide is formed from the light output surface towards the light input surface, thereby minimizing the waveguide spacing. Further details thereon will be hereinafter described.
  • the area of the light output surface 128 can be made larger, as compared with the lattice-pattern in Fig. 1.
  • a light output surface 128 having a width of about 10mm can be printed using an inkjet plotter, thereby enabling a reduction in manufacturing costs.
  • a resin having a refraction index larger than that of the photopolymerizable resin 130 is filled and cured in the space 122a (step 206), and the dot-pattern photomask 110 is then released (step 207).
  • the dot-pattern photomask 110 may be removed in a previous step.
  • a resin 150 having a higher refraction index is filled in the space to be formed into a waveguide.
  • an optical device has a large size and thus a certain degree of rigidity is required.
  • a transparent support plate 152 is bonded to the front face or the rear face thereof, as shown in Fig. 15.
  • two different ways can be employed. For one approach, as illustrated in Fig. 15, a resin 150 having a refraction index larger than that of the photopolymerizable resin 130 is filled to the same thickness or thicker than the length of the waveguide. Thereafter, a transparent support plate 152 is placed thereon and then polymerized to be cured. In this case, the support plate 152 or the resin to be filled in the space may contain a diffuser or particles in order to facilitate the diffusion thereof.
  • the resin 150 is filled thicker, as much as or more than the thickness of the transparent support plate 152, and then polymerized to be cured, as shown in Fig. 14.
  • unnecessary light reflection or light loss which may be caused by a refraction index difference with the support plate 152, can be alleviated, but the cured waveguide resin 150 must have an adequate strength.
  • the waveguide resin 150 to be filled in the space 122a may contain a diffuser or particles to thereby facilitate the diffusion function thereof.
  • a photosensitive adhesive 160 is coated on the entire surface of the light output surface 128 side (step 208), and then light-absorbing particles 162 of blackish color such as carbon-black, iron oxide or the like are applied to the photosensitive adhesive 160 (step 209).
  • the photosensitive adhesive 160 include an acrylic or iso-vinyl photopolymerizable adhesive.
  • collimated ultraviolet rays 30 are radiated from the light input surface 127 side towards the light output surface 128 side upon which the light-absorbing particles are attached (step 210).
  • that portion of the photosensitive adhesive 160 exposed to the ultraviolet rays loses its adhesive force.
  • the surface on which the light- absorbing particles 162 are attached is cleansed so as to release the light-absorbing particles 162 on the light output surface 128 of the waveguide 120 (step 211), the adhesive 160 having lost its adhesive force by the ultraviolet radiation.
  • an optical device for a display 100 according to the invention is provided. The portion where the light-absorbing particles 162 remain not released becomes a light-absorbing region.
  • the attachment of light-absorbing particles using a photosensitive adhesive may be applied to an optical device for a display having other types of waveguide in the same manner as in Fig. 16. This will be explained in detail, referring to Figs. 19 to 22, which show another example for the attachment of light-absorbing particles using a photosensitive adhesive.
  • the waveguide 120 is formed of a transparent resin.
  • a first resin 152a which does not contain light-absorbing particles of black color such as carbon-black and has a refraction index smaller than that of the waveguide 120.
  • a photosensitive adhesive 160 coated on the front face of the optical device including the light output surface 128 of the waveguide 120 is a photosensitive adhesive 160, which loses its adhesive force when exposed to ultraviolet rays.
  • light-absorbing fine particles 162 of black color are attached on the photosensitive adhesive 160, as shown in Fig. 20.
  • Fig. 20 the photosensitive adhesive 160
  • ultraviolet rays are radiated from the light input surface 127 towards the light output surface 128 such that the light output surface 128 of the waveguide 120 can selectively lose the adhesive force of the photosensitive adhesive and release the light-absorbing particles 162 attached thereon through a surface cleansing process as shown in Fig. 21.
  • an optical device of the invention can be obtained, as shown in Fig. 22. That portion, in which the light- absorbing particles 162 are removed, forms a particle-free region 162a that allows light to pass through the waveguide 120 from the light input surface 127 towards the front face of the device.
  • the photosensitive adhesive may be in film form or in liquid form, or any other form of adhesive or resin as long as it has a strong adhesive force, but loses its adhesive force when exposed to ultraviolet radiation.
  • a transparent resin layer 180 may be further formed for the purpose of surface stabilization and protection.
  • the photosensitive adhesive 160 may include acrylic or iso-vinyl photopolymerizable adhesive.
  • the optical device described in conjunction with Figs. 19 to 22 is fabricated through the following procedures.
  • a plurality of tapered waveguides each having a slant face for reflecting and diffusing incident lights are formed on a thin resin plate so as to be disposed at regular intervals thereon.
  • a first resin having a refraction index smaller than that of the waveguide 120.
  • a photosensitive adhesive 160 On the surface of the light output surface 128 side, i.e., on the surface of the narrower side of the waveguide 120 is coated a photosensitive adhesive 160, which loses its adhesive force when exposed to ultraviolet rays.
  • the coated photosensitive adhesive 160 On the surface of the coated photosensitive adhesive 160 are attached light-absorbing particles 162 of black color for absorbing external light and reducing the quantity of reflected lights. Thereafter, ultraviolet rays are radiated, from the opposite side of the coated photosensitive adhesive 160, i.e. from the light input surface 127, via the waveguide 120, towards the light output surface 128, i.e., towards the coated photosensitive adhesive 160. Then, the black light-absorbing particles disposed on the waveguide 120 are released from the photosensitive adhesive 160.
  • a transparent resin may be coated on the adhered black light- absorbing particles 162 and cured to thereby form a transparent resin layer 180, which thereby stabilizes the fixed light-absorbing particles.
  • the lights inputted into the waveguide 120 can significantly reduce the amount of lights to be absorbed into conventional light-absorbing particles, which are contained in the light-absorbing region 129.
  • Figs. 23 and 24 illustrate a tapered waveguide having another type of light input surface, which is formed according to the dot shape in the dot-pattern photomask.
  • Figs. 23 and 24 show the advantages of the invention in not generating a light-loss area, as compared to the conventional techniques of Figs. 3 and 4.
  • the bottom surface thereof is not limited to a flat plane.
  • the connection area between the neighboring light input surfaces takes on an apex-like point 133, and thus the light input surfaces 127 may be integrated substantially into a single surface. Accordingly, the optical device of the invention does not produce a light loss area in the light input surface area thereof.
  • the conventional waveguide generates a light loss area, at least corresponding to the line width in the photomask.
  • the waveguide does not form a spacing in-between or form an ultimately small apex-like point 133 in the light input surface thereof, thereby minimizing the light loss.
  • the above-described method of fabricating an optical device may be applied to the fabrication of an optical device for a front-projection display. This will be explained, referring to Figs. 25 and 26. That is, after a surrounding region 132 of waveguide is formed in the same way as described previously, a coating for increasing reflection rate, such as a metallic coating 124 or a total reflection coating, is performed, without filling a resin 130 in the space 122a.
  • a dot-pattern opaque region 144 may be printed directly on the support film 140, or a transparent support film 140 with a dot-pattern opaque region 144 printed thereon may be used, thereby enabling a continuous process without intermission. In this case, the support film does not need to be removed after finishing the process, thus improving the production efficiency, avoiding limitation in the size, and further simplifying the production facility.
  • the waveguide of Figs. 25 and 26 structurally carries out the total reflection in a stable manner, as illustrated in Fig. 27.
  • a resin 154 having a good light transmissivity may be filled in the space 122a, as shown in Fig. 28, or a diffuser or diffusing particles may be introduced, thereby enhancing the structural stability thereof.
  • the resin 54 has a lower refraction index.
  • the optical device of the invention can be applied to a projection TV, and a monitor display, in particular, a screen for rear-projection TVs, and a screen for other rear-projection systems. It can also be applied to the optical parts of a display device or system such as a TFT-LCD, a PDP TV or a screen for CRT monitors, as well as a display for an advertising board or other illumination devices.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne un dispositif optique pour un écran comprenant un guide d'onde à impédance croissante et un procédé de fabrication de ce dispositif. Un photomasque est préparé, lequel comprend une pluralité de régions opaques disposées à des intervalles donnés et des régions transparentes disposées entre les régions opaques. Une résine photopolymérisable est appliquée sur une surface avant du photomasque. La surface arrière du photomasque est exposée aux rayons de lumière de sorte que la partie exposée à la lumière de la résine photopolymérisable est polymérisée afin de former une région environnante de guide d'onde. La partie non polymérisée de la résine photopolymérisable est enlevée afin de former un espace dans un guide d'onde. Un matériau ayant un indice de réfraction différent de la région environnante est disposé fixe du côté intérieur de la paroi latérale de l'espace afin de former un guide d'onde. Le photomasque est libéré, puis un matériau noir est disposé sur la surface de la région environnante du côté de la surface de sortie de lumière afin de former la région absorbant la lumière.
PCT/KR2005/000421 2004-05-31 2005-02-16 Dispositif optique pour un ecran comprenant un guide d'onde a impedance croissante et procede de fabrication WO2005116732A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR10-2004-0039320 2004-05-31
KR10-2004-0039322 2004-05-31
KR1020040039322A KR100470324B1 (ko) 2004-05-31 2004-05-31 쐐기형 도파관을 가지는 디스플레이용 광학소자와 그의제조방법
KR1020040039320A KR100450715B1 (ko) 2004-05-31 2004-05-31 쐐기형 도파관을 가지는 디스플레이용 광학소자 및 그의제조방법

Publications (1)

Publication Number Publication Date
WO2005116732A1 true WO2005116732A1 (fr) 2005-12-08

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3106218A1 (fr) * 2020-01-14 2021-07-16 Isorg Filtre angulaire et son procédé de fabrication

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5481385A (en) * 1993-07-01 1996-01-02 Alliedsignal Inc. Direct view display device with array of tapered waveguide on viewer side
WO1996021884A1 (fr) * 1995-01-12 1996-07-18 Alliedsignal Inc. Ecran de visualisation a reseau de guides d'ondes coniques
US6538813B1 (en) * 2000-09-19 2003-03-25 Honeywell International Inc. Display screen with metallized tapered waveguides

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5481385A (en) * 1993-07-01 1996-01-02 Alliedsignal Inc. Direct view display device with array of tapered waveguide on viewer side
WO1996021884A1 (fr) * 1995-01-12 1996-07-18 Alliedsignal Inc. Ecran de visualisation a reseau de guides d'ondes coniques
US6538813B1 (en) * 2000-09-19 2003-03-25 Honeywell International Inc. Display screen with metallized tapered waveguides

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3106218A1 (fr) * 2020-01-14 2021-07-16 Isorg Filtre angulaire et son procédé de fabrication
WO2021144316A1 (fr) * 2020-01-14 2021-07-22 Isorg Filtre angulaire et son procede de fabrication

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