Display backlights with adjustable narrow viewing angle

• US 9,348,160 B2
• Filed: 06/24/2010
• Issued: 05/24/2016
• Est. Priority Date: 06/24/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Hsu, Feng-Hsiung
• Primary Examiner(s): Beck, Leron
• Application Number:
  US12/822,648
• Publication Number:
  US 20110317399A1
• Time in Patent Office: 2,161 Days
• Field of Search: 348/58
• US Class Current: 1/1
• CPC Class Codes: G02F 1/1323 Arrangements for providing a switchable viewing angle
• CPC Class Codes: G02F 1/133 Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements arrangements or circuits for control of liquid crystal elements in a matrix, not structurally associated with these elements G09G3/36
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable

Abstract

Display components (e.g., liquid crystal displays (LCDs)) are viewable at different viewing angles, for example, by a first user positioned directly in front of the display and by a second user positioned to one side of the display. Many displays present a consistent display across a wide range of viewing angles, but these displays may consume energy and/or compromise user privacy. Presented herein are configurations of backlights for display devices featuring an adjustable viewing angle, such that a user may select a narrower viewing angle in usage scenarios involving power consumption or privacy, and may select a wider viewing angle in usage scenarios involving plentiful power and fewer privacy concerns. Such configurations may include multiple banks of backlight lamps generating backlight at different viewing angles; an electrowetting electrode as an adjustable collimator; adjustable diffusers that may adjustably scatter light passing therethrough; and/or a combination of such adjustable elements.

Claims

1. A backlight for a display surface providing an adjustable viewing angle of light emitted by the display surface that is selectable by a user, the backlight comprising:

at least one wide-beam lamp configured to emit light at a wide angle directed toward the display surface;

at least one narrow-beam lamp configured to emit light at a narrow angle directed toward the display surface, wherein the narrow angle is less than the wide angle;

a light angle selector having a wide viewing angle setting and a narrow viewing angle setting, for setting a viewing angle of the light emitted by the display surface, and configured to;

power the at least one wide-beam lamp in response to a selection by the user of the wide viewing angle setting while leaving the at least one narrow beam lamp unpowered, and

power the at least one narrow-beam lamp in responses to a selection by the user of the narrow viewing angle setting while leaving the at least one wide-beam lamp unpowered;

an optical coupler positioned between at least one lamp and the display surface and configured to couple the light with the display surface; and

an optical light guide positioned between at least one lamp and the display surface and configured to distribute the light across the display surface.

2. The backlight of claim 1:

the backlight comprising at least one moderate-beam lamp configured to emit light at an angle less than the wide angle of the wide-beam lamp and greater than the narrow angle of the narrow-beam lamp; and

the light angle selector configured to activate one of the at least one wide-beam lamp, the at least one moderate-beam lamp, and the at least one narrow-beam lamp.

3. The backlight of claim 1, further comprising:

a forward polarizer positioned between at least one lamp and the display surface and configured to transmit light having a light polarity approximately equal to a desired light polarity.

4. The backlight of claim 3, the forward polarizer comprising a reflective forward polarizer configured to reflect backwardly light having a light polarity not approximately equal to a desired light polarity.

5. The backlight of claim 4, the reflective forward polarizer comprising a wire grid polarizer.

6. The backlight of claim 4, the reflective forward polarizer comprising an interference reflector composed of a biaxial film.

7. The backlight of claim 1, further comprising:

a back reflector positioned around at least one lamp and configured to reflect light toward the display surface.

8. A backlight for a display surface providing an adjustable viewing angle of light emitted by the display surface that is selectable by a user, comprising:

at least one lamp configured to emit light;

an optical coupler positioned between the at least one lamp and the display surface and configured to couple the light with the display surface;

an optical light guide positioned between the at least one lamp and the display surface and configured to distribute the light across the display surface; and

an adjustable collimator positioned between the optical light guide and the display surface and configured to, responsive to a selection by the user of a selected adjustable viewing angle setting of the light emitted by the display surface, align the light toward the display surface with a collimation angle of the light emitted by the at least one lamp, the collimation angle adjustable between a zero-degree collimation angle and a nonzero-degree collimation angle inversely proportional to a collimation magnitude according to the selected viewing angle setting selected by the user; and

an adjustable diffuser positioned between the collimator and the display surface and configured to diffuse the light proportional to a diffuser voltage applied to the adjustable diffuser.

9. The backlight of claim 8, the adjustable collimator comprising an electrowetting electrode providing an adjustable collimation angle proportional to an electrowetting voltage applied to the electrowetting electrode.

10. The backlight of claim 9, further comprising:

a light angle selector configured to apply to the electrowetting electrode an electrowetting voltage selected from at least three electrowetting voltages respectively producing a collimation angle.

11. The backlight of claim 8, the adjustable collimator configured to align the light toward the display surface with a collimation angle less than an angle of light emitted by the optical light guide.

12. The backlight of claim 11, the adjustable diffuser comprising a polymer-dispersed liquid crystal.

13. The backlight of claim 11, the adjustable diffuser comprising a polymer-stabilized cholesteric texture.

14. The backlight of claim 11, further comprising:

a light angle selector configured to apply to the adjustable diffuser a diffuser voltage selected from at least three diffuser voltages respectively producing a collimation angle.

15. The backlight of claim 8, further comprising:

a forward polarizer positioned between at least one lamp and the display surface and configured to transmit light having a light polarity approximately equal to a desired light polarity.

16. The backlight of claim 15, the forward polarizer comprising a reflective forward polarizer configured to reflect backwardly light having a light polarity not approximately equal to a desired light polarity.

17. The backlight of claim 16, the reflective forward polarizer comprising a wire grid polarizer.

18. The backlight of claim 16, the reflective forward polarizer comprising an interference reflector composed of a biaxial film.

19. The backlight of claim 8, further comprising:

a back reflector positioned around at least one lamp and configured to reflect light toward the display surface.

20. An electronic device comprising a backlight for a display surface providing an adjustable viewing angle of light emitted by the display surface that is selectable by a user, the backlight comprising:

at least one wide-beam lamp configured to emit light at a wide angle;

at least one narrow-beam lamp configured to emit light at a narrow angle directed toward the display surface;

at least one first light angle selector having a wide viewing angle setting and a narrow viewing angle setting, for setting a viewing angle of light emitted by the display surface, and configured to power;

the at least one wide-beam lamp responsive to a selection by the user of the wide viewing angle setting of the light emitted by the display surface, while leaving the at least one narrow beam lamp unpowered; and

the at least one narrow-beam lamp responsive to a selection by the user of the narrow viewing angle setting of the light emitted by the display surface while leaving the at least one wide-beam lamp unpowered;

an optical coupler positioned between at least one lamp and the display surface and configured to couple the light with the display surface;

a solid optical light guide positioned between at least one of the at least one wide-beam lamp and the at least one narrow-beam lamp and the display surface and configured to distribute the light across the display surface;

an adjustable collimator positioned between the optical light guide and the display surface and configured to align the light toward the display surface with a collimation angle of the light emitted by the at least one of the at least one wide-beam lamp and the at least one narrow-beam lamp, the collimation angle adjustable between a zero-degree collimation angle and a nonzero-degree collimation angle inversely proportional to a collimation magnitude, the adjustable collimator comprising an electrowetting electrode providing an adjustable collimation angle proportional to an electrowetting voltage applied to the electrowetting electrode according to a selected viewing angle setting received from the user;

a second light angle selector configured to apply to the electrowetting electrode an electrowetting voltage selected according to the selected viewing angle setting from at least three electrowetting voltages respectively producing a collimation angle;

an adjustable diffuser positioned between the collimator and the display surface and configured to diffuse the light proportional to a diffuser voltage applied to the adjustable diffuser, the adjustable diffuser selected from a set of adjustable diffusers comprising;

a polymer-dispersed liquid crystal, and

a polymer-stabilized cholesteric texture;

a third light angle selector configured to apply to the adjustable diffuser a diffuser voltage selected from at least three diffuser voltages respectively producing a collimation angle, where the diffuser voltage is selected according to the selected viewing angle setting received from the user;

a forward polarizer positioned between at least one lamp and the display surface and configured to transmit light having a light polarity approximately equal to a desired light polarity according to the selected viewing angle setting received from the user, the forward polarizer comprising a reflective forward polarizer configured to reflect backwardly light having a light polarity not approximately equal to a desired light polarity, and the forward polarizer selected from a set of forward polarizers comprising;

a wire grid polarizer, and

an interference reflector composed of a biaxial film; and

a back reflector positioned around at least one lamp and configured to reflect light toward the display surface.