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US-12625398-B2 - Light modulation unit and display device thereof

US12625398B2US 12625398 B2US12625398 B2US 12625398B2US-12625398-B2

Abstract

The invention provides a light modulation unit including a collimating optical layer and an optical film. The optical film has a light exit surface and a light entrance surface opposite to the light exit surface. The collimation optical layer and the light entrance surface of the optical film are disposed relatively. The light exit surface forms a plurality of microstructures, each of which has a height h in the normal direction of the light exit surface and a virtual aperture φ in the x-coordinate axis direction parallel to the light exit surface, and the ratio of the height h to the virtual aperture φ (h/φ) is 0.2 to 1. The light modulation unit of the present invention has the function of adjusting the brightness of anti-peep viewing angles, and can improve the display brightness of front viewing angles through light pattern control.

Inventors

  • Wen-Tai SHEN
  • Yu-Huan Chiu

Assignees

  • Darwin Precisions Corporation

Dates

Publication Date
20260512
Application Date
20250117
Priority Date
20240813

Claims (17)

  1. 1 . A light modulation unit, comprising: an optical film, having a light exit surface and a light entrance surface opposite to the light exit surface, wherein the light exit surface forms a plurality of microstructures, each of the microstructures has a boundary connected to a boundary of a microstructure adjacent thereto, an orthographic projection of the boundary of the microstructure on the light exit surface is polygonal, the microstructures each have a height (h) in a normal direction of the light exit surface, the microstructures each also have a virtual aperture (φ) in an x-coordinate axis direction parallel to the light exit surface, and a ratio (h/φ) of the height (h) to the virtual aperture (φ) is 0.2 to 1; and a collimating optical layer, arranged opposite to the light entrance surface of the optical film; wherein the collimating optical layer is an anti-peep film.
  2. 2 . The light modulation unit according to claim 1 , wherein the ratio (h/φ) of the height (h) to the virtual aperture (φ) is 0.3 to 0.7.
  3. 3 . The light modulation unit according to claim 1 , wherein the microstructures each have a surface profile, and the surface profile satisfies the following functional form: s ⁡ ( x ) = x 2 R + R 2 + ( k + 1 ) ⁢ x 2 wherein s(x) represents the surface profile of each of the microstructures in an x-coordinate axis, value x represents a position of a vertical projection of the surface profile on the x-coordinate axis, value R represents a curvature radius of a vertex of each of the microstructures, value k represents a conic constant of each of the microstructures, and the microstructures have the same value R and value k.
  4. 4 . The light modulation unit according to claim 3 , wherein a ratio (k/R) of the conic constant to the curvature radius satisfies the following condition: - 1 87.5 1 / μ ⁢ m ≤ k / R ≤ - 20 ⁢ 1 / μ ⁢ m .
  5. 5 . The light modulation unit according to claim 3 , wherein the microstructures are each suitable for forming a light type, the light type has a viewing angle, and the viewing angle satisfies the following functional form: FOV = A ⁡ ( k / R ) + B wherein FOV represents the viewing angle of the light type, value A and value B satisfy the following condition: −0.1≤A≤−1, and B is a constant greater than 0.
  6. 6 . The light modulation unit according to claim 3 , wherein the conic constant k satisfies the following condition: −1.5≤k≤−0.8.
  7. 7 . The light modulation unit according to claim 3 , wherein the curvature radius R satisfies the following condition: 0.008 μm≤R≤0.04 μm.
  8. 8 . The light modulation unit according to claim 1 , wherein the virtual aperture (φ) of each of the microstructures satisfies the following condition: 10 μm≤φ≤250 μm.
  9. 9 . The light modulation unit according to claim 3 , wherein the virtual aperture (φ) of each of the microstructures is a difference between two adjacent values x when the functional form s(x) of the surface profile is 0 and satisfies the following condition: 10 μm≤φ≤250 μm.
  10. 10 . The light modulation unit according to claim 1 , wherein the height (h) of each of the microstructures satisfies the following condition: 10 μm≤h≤50 μm.
  11. 11 . The light modulation unit according to claim 3 , wherein the height (h) of each of the microstructures is a maximum value of the functional form s(x) of the surface profile and satisfies the following condition: 10 μm≤h≤50 μm.
  12. 12 . The light modulation unit according to claim 1 , wherein the microstructures protrude from or recess into the light exit surface.
  13. 13 . The light modulation unit according to claim 1 , wherein a material of the optical film is at least one of polycarbonate, polyethylene terephthalate, polypropylene, polyvinyl chloride, or polydimethylsiloxane.
  14. 14 . A display device, comprising: a light modulation unit, comprising: an optical film, having a light exit surface and a light entrance surface opposite to the light exit surface, wherein the light exit surface forms a plurality of microstructures, each of the microstructures has a boundary connected to a boundary of a microstructure adjacent thereto, an orthographic projection of the boundary of the microstructure on the light exit surface is polygonal, the microstructures each have a height (h) in a normal direction of the light exit surface, the microstructures each also have a virtual aperture (φ) in an x-coordinate axis direction parallel to the light exit surface, and a ratio (h/φ) of the height (h) to the virtual aperture (φ) is 0.2 to 1; and a collimating optical layer, arranged opposite to the light entrance surface of the optical film; a display panel, opposite to the light exit surface of the optical film; and a first light emitting unit, arranged opposite to the collimating optical layer of the light modulation unit, and the light modulation unit being located between the display panel and the first light emitting unit; wherein the first light emitting unit emits an initial light beam to the collimating optical layer, the initial light beam passes through the collimating optical layer to form a collimated beam, the collimated beam passes through the light entrance surface to enter the optical film and then exits from the microstructures of the light exit surface to form a divergent light beam, and the divergent light beam has a divergence angle relative to a normal of the light entrance surface; the display device further comprising a second light emitting unit disposed between the display panel and the optical film, wherein the second light emitting unit comprises a second light guide plate and at least one second light source disposed on at least one side surface of the second light guide plate, wherein the display device is able to switch between a plurality of modes comprising: a privacy mode: when the first light emitting unit is turned on and the second light emitting unit is turned off, the divergent light beam passes through the second light emitting unit and the display panel to form a first emitted light beam, and the first emitted light beam has a first maximum light emission angle relative to a normal of a plane of the display panel away from the light exit surface; and a sharing mode: when the first light emitting unit is turned on and the second light emitting unit is turned on, at least one light beam emitted by the second light emitting unit passes through the second light emitting unit and the display panel to form a second emitted light beam, the second emitted light beam has a second maximum light emission angle relative to the normal of the plane of the display panel away from the light exit surface, and the first maximum light emission angle is less than the second maximum light emission angle.
  15. 15 . The display device according to claim 14 , wherein the first light emitting unit comprises: a first light guide plate, having at least one side surface; and at least one first light source, disposed on the at least one side surface of the first light guide plate.
  16. 16 . The display device according to claim 14 , wherein the first light emitting unit comprises: a first light guide plate, having an upper surface close to the collimating optical layer; and at least one first light source, disposed on the upper surface of the first light guide plate.
  17. 17 . The display device according to claim 14 , wherein when the divergence angle θ is 0 degrees, the divergent light beam has first brightness; and when 0 degrees<θ≤20 degrees or −20 degrees≤θ<0 degrees, the divergent light beam has second brightness, and the second brightness is 90% to 105% of the first brightness.

Description

FIELD OF THE INVENTION The present invention relates to a light modulation unit, particularly a light modulation unit for adjusting the brightness of anti-peep viewing angles and a display device thereof. BACKGROUND OF THE INVENTION With the increasing awareness of privacy protection, display devices with an anti-peep function are becoming more popular. In the prior art, a light control film is arranged to adjust the light emission angle, allowing light to be emitted within a small viewing angle range, thus providing the user visibility at the orthogonal angle and restricting visibility at non-orthogonal angles. FIG. 1 is a curve of a viewing angle and brightness of a display device in a comparative example of the prior art. As shown in FIG. 1, when a user views an image at the orthogonal angle, the brightness significantly decreases as the viewing angle increases, causing viewing discomfort to the user. Thus, those in this industry are eager to resolve the issue of viewing discomfort with the anti-peep display devices. SUMMARY OF THE INVENTION The present invention provides a light modulation unit that can alleviate the situation where the brightness significantly decreases as the viewing angle increases when the user views the image at the orthogonal angle, thereby enhancing viewing comfort. The light modulation unit provided by the present invention includes an optical film and a collimating optical layer. The optical film has a light exit surface and a light entrance surface opposite to the light exit surface. A plurality of microstructures are formed on the light exit surface, and each microstructure has a plurality of boundaries. Each microstructure has the boundary connected to a boundary of a microstructure adjacent thereto, and an orthographic projection of the boundary of each microstructure on the light exit surface is polygonal. Each microstructure has a height h in the normal direction of the light exit surface and a virtual aperture φ in the x-coordinate axis direction parallel to the light exit surface, and the ratio (h/φ) of the height h to the virtual aperture φ is 0.2 to 1. The collimating optical layer is opposite to the light entrance surface of the optical film. In an embodiment of the present invention, the ratio (h/φ) of the height h to the virtual aperture φ is 0.3 to 0.7. In an embodiment of the present invention, the microstructures each have a surface profile, and the surface profile satisfies the following functional form: s⁡(x)=x2R+R2+(k+1)⁢x2 Where s(x) represents the surface profile of each of the microstructures in an x-coordinate axis, value x represents a position of a vertical projection of the surface profile on the x-coordinate axis, value R represents a curvature radius of a vertex of each of the microstructures, value k represents a conic constant of each of the microstructures, and the microstructures have the same value R and value k. In an embodiment of the present invention, a ratio (k/R) of the conic constant to the curvature radius satisfies the following condition: −187.5 1/μm≤k/R≤−20 1/μm. In an embodiment of the present invention, the microstructures are each suitable for forming a light type, the light type has a viewing angle, and the viewing angle satisfies the following functional form: FOV=A⁡(k/R)+B Where FOV represents the viewing angle of the light type, and value A and value B satisfy the following condition: −0.1≤A≤−1, and B is a constant greater than 0. In an embodiment of the present invention, the conic constant k satisfies the following condition: −1.5≤k≤−0.8. In an embodiment of the present invention, the curvature radius R satisfies the following condition: 0.008 μm≤R≤0.04 μm. In an embodiment of the present invention, the virtual aperture φ of each of the microstructures satisfies the following condition: 10 μm≤φ≤250 μm. In an embodiment of the present invention, the virtual aperture φ of each of the microstructures is a difference between two adjacent values x when the functional form s(x) of the surface profile is 0 and satisfies the following condition: 10 μm≤φ≤250 μm. In an embodiment of the present invention, the height h of each of the microstructures satisfies the following condition: 10 μm≤h≤50 μm. In an embodiment of the present invention, the height h of each of the microstructures is a maximum value of the functional form s(x) of the surface profile and satisfies the following condition: 10 μm≤h≤50 μm. In an embodiment of the present invention, the microstructures protrude from or recess into the light exit surface. In an embodiment of the present invention, a material of the optical film may be polycarbonate, polyethylene terephthalate, polypropylene, polyvinyl chloride, polydimethylsiloxane, or a combination thereof. In an embodiment of the present invention, the collimating optical layer is an anti-peep film or lens. The present invention further provides a display device, including the foregoing light modulation unit, a display p