WO2017065745A1

WO2017065745A1 - Privacy backlight module

Info

Publication number: WO2017065745A1
Application number: PCT/US2015/055256
Authority: WO
Inventors: Wei-Kuang Chu; Kuan-Ting Wu; Chi-hao CHANG (james)
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2015-10-13
Filing date: 2015-10-13
Publication date: 2017-04-20
Anticipated expiration: 2018-04-13

Abstract

In one example, a privacy backlight module is described which includes a first light guide plate having first prismatic structures formed on a first bottom surface. Each first prismatic structure includes a first inclined surface and a second inclined surface connected to the first inclined surface. The privacy backlight module includes a second light guide plate disposed above or below the first light guide plate and having second prismatic structures formed on a second bottom surface. Each second prismatic structure includes a third inclined surface and a fourth inclined surface connected to the third inclined surface. The privacy backlight module includes a first light source disposed along a left surface of the first light guide plate and a second light source disposed along a right surface of the second light guide plate.

Description

PRIVACY BACKLIGHT MODULE

BACKGROUND

[0001] Backlight modules may be used to illuminate display units of electronic devices. A backlight module may include a light guide plate which converts a linear light source or a point Sight source into a surface light sourc by distributing light coming out from the light source over the display units.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Examples are described in the following detailed description and in reference to the drawings, in which:

[00033 f¾- 1 depicts an example backlight module;

[00043 Fig. 2 depicts the example backlight module of Fig. 1 with additional components;

[0005] Fig. 3 depicts the example backlight modu!e of Fig. 2 with additional components;

[00063 Fig. 4 depicts the example backlight module of Fig. 3 with additional components;

[00073 f¾- depicts exploded view of fight guide plates of the backlight module, in accordance with an example;

[00083 Fig. 8A depicts exploded view of light guide plates of the backlight module, in accordanc with anothe example;

[0009] Fig. 8B depicts exploded view of light guide plates of the backlight module, in accordance with further example;

[00103 Fig. 7 depicts exploded view of light guide plates of the backlight module, in accordance with yet another example; [0011] Fig. 8 depicts exploded view of fight guide plates of the backlight module, in accordance with further example;

OOI23 Fig. 9 depicts exploded view of Sight guide plates of the backlight module, in accordance with further example;

[0013] Fig. 10 depicts exploded view of light guide plates of the backlight module, in accordance with yet another example; and

IOOI43 Fig. 11 depicts exploded view of light guide plates of the backlight module, in accordance with another example.

DETAILED DESCRIPTION

[00 SJ Backlight modules may be used to illuminate display units of electronic devices. An electronic device may be used in a public or open space. In this case, contents/information displayed on the display unit of the electronic device may be viewed privately by protecting the contents/information from other persons.

[0016J Example techniques use privacy screens on the display units for protecting the contents/information displayed on the display units of the electronic devices from other persons. For example, the privacy screens may be optical filters which can minimize light exit angles from the display units. The privacy screens may be manually disposed on the display units of the electronic devices. Further, the privacy screens may be removed manually from the display units. Disposing and removing the privacy screens on the display unit may be a frequent process which may cause inconvenience to the user. Also, the privacy screens may be preserved carefully when removed from the display unit for using the privacy screens for next privacy operation,

[00173 The present application discloses techniques to provide backlight module in which viewing angle is switchabie between a wide viewing angle and a narrow viewing angle. The wide viewing angle may refer to a maximum angle at which information/content displayed on a display can be viewed. The wide vsewing angle is greater than the narrow viewing angle. For example, to enable privacy, the viewing angle (e.g. , range of viewing the sensitive information on the display) may be restricted to prevent other users from viewing the display. In this case, the viewing angle of the display may be switched to the narrow viewing angle to enable privacy of the information/content displayed on a display. On the other hand, in norma! mode of operation, the viewing angle of the display may be switched to the wide viewing angle.

[0018] Fig. 1 depicts an example privacy backlight module 100 which may include a first Sight guide piate 102 and a second light guide plate 104. The first light guide plate 102 may include a first bottom surface 106. The first bottom surface 106 may include first prismatic structures 108 formed thereon. Further, the second light guide plate 104 includes a second bottom surface 110. The second bottom surface 110 may include second prismatic structures 1 2 formed thereon. Furthermore, each of the first prismatic structures 108 may include a first inclined surface 114 and a second inclined surface 116. The second inclined surface 116 may be connected to the first inclined surface 1 14. Further, the first inclined surface 1 4 forms a first angle θι with the first bottom surface 108 and the second inclined surface 1 6 forms a second angie 82 with the first bottom surface 106. In each of the first prismatic structures 108_s the first angle Θ1 is smaller than the second angle 82.

OOI93 Furthermore, each of the second prismatic structures 1 12 may include a third inclined surface 118, and a fourth inclined surface 120. The third inclined surface 1 18 may be connected to the fourth inclined surface 120, The third inclined surface 118 forms a third angie 83 with the second bottom surface 110 and the fourth inclined surface 20 forms a second angle 84 with the second bottom surface 1 10. In each of the second prismatic structures 112, the third angle 63 is greater than the second angle Θ4, Further, either of the first light guide plate 102 and the second Sight guide plate 104 is disposed on the other light guide plate among the two light guide plates 102 and 104 to form a combined light guide plate. [0020] Furthermore, the privacy backlight module 100 may include a first fight source 122 and a second Sight source 124. Example first Sight source 122 and the second light source 124 may include light emitting diodes (LEDs) or cold cathode fluorescent lamps (CCFLs), However, in other examples, other types of light sources may also be used. Further, the first light source 122 may be disposed along a left surface 128 of the first light guide 102 and the second light source 124 may be disposed along a right surface 128 of the second light guide plate 104. That is, the first light source 122 and the second light source 124 may be disposed on opposite surfaces of the combined light guide plate. In other words, the first light source 122 and the second light source 124 are separated by the combined Sight guide plate. The first light source 122 and the second light source 124 may enable switching of viewing angle (i.e., between the wide viewing angle 130A and the narrow viewing angle 308) of the privacy backlight module 100. The switching between the wide viewing angle 130A and the narrow viewing angle 130B may be performed by controlling on/off state of the first light source 122 and the second light source 124. That is, the function of switching the viewing angle is provided by controlling the activation and/or deactivation of the first light source 122 and the second light source 124.

[00213 For example, the first light source 122 and the second Sight source 124 may enable switching between a first mode Mi and a second mode iVfe af the privacy backlight module 100, The first mode fVh may refer to a mode of operation of the privacy backlight module 100 when either the first light source 122 or the second light source 124 is activated. The first mode may provide a narrow viewing angle 1308 of the privacy backlight module 100. Similarly, the second mode M≥ may refer to a mode of operation of the privacy backlight module 00 when both the first light source 122 and the second light source 124 are activated. The second mode i2 may provide a wide viewing angle 130A of the privacy backlight module 100. That is, the first light source 122 is turned on and the second Sight source 124 is turned off at the first mode Mi. or, the second light source 124 is turned on and the first Sight source 122 is turned off at the first mode Mi. The first light source 122 and the second light source 1 4 are both turned on at the second mode M2. [0022] Since the first mode Mi may provide a narrow viewing angle 130B, the first mode Mi may be used for privacy mode of the backlight module 100. Simi!ariy, since the second mode fVfe may provide a wide viewing angle 130A, the second mode (v s may be used for norma! mode of the backlight module 100, Besides, the backlight module 100 may have greater brightness when operated in the second mode fv than when operated in the first mode Mi , therefore, in the second mode IVh the brightness of the at feast one of the first iighf source 122 and the second Sight source 124 may be minimized to avoid inconsistency of the brightness when the backlight module 100 is operated in the first mode Mi or the second mode M2.

[0023] In one example, the switching operation between the first mode Mi and the second mode Ms can be performed through switch buttons or through a keyboard, in this case, corresponding circuits may be provided for controlling the on/off state of the first light source 122 and the second light source 124. In another example, the switching operation between the first mode Mi and the second mode M2 can be performed through switches that are operated by executing instructions in combination with other hardware devices.

[0024] Referring now to Fig. 2 which illustrates a schematic representation 200 of the exampl privacy backlight module 100 with additional components. In this example, the privacy backlight module 100 may include a diffuser 202 and an array of prisms 204. The diffuser 202 is disposed on the combined light guide plate formed by the first light guide plate 102 and the second light guide plate 04. Further, the array of prism 204 may be disposed on the diffuser 202. In this example, the array of prisms 204 may for a light enhancement structure/ plate. In one example, the prisms 204 are arranged in a linear array.

[002SJ Turning now to Fig. 3 which illustrates a schematic representation 300 of the example privacy backlight module 100 with additional components. In this example, the privacy backlight moduie 100 may include a display unit 302 among other components as described with reference io Fig. 2. The display unit 302 is disposed on the array of prisms 204. Example display unit 302 may be liquid crystal display (LCD), organic light-emitting diode (OLED) display, polymer tight-emiiting diode (PLED) display, plasma display, bi-stable display, and the like.

0026| Referring now to Fig. 4 which illustrates a schematic representation 400 of the example privacy backlight module 100 with further additional components. In this example, the privacy backlight module 100 may include a reflector 402 among other components as described with reference to Fig. 3. The reflector 402 may be mounted below the combined light guide piate. That is, the reflector 402 may be mounted opposite to the surface of the combined light guide plate on which the diffuser 202 is disposed, in one example, an array of multiple reflectors may be used to form the reflectors 402,

[0027J In the first mode M 1 operation of the backlight module 100, when the first light source 122 is activated, Sight generated from the first Sight source 122 may be reflected by the first inclined surface 114 and the second inclined surface 1 16, or refracted by the first inclined surface 1 14 and the second inclined surface 118 to exit the first light guide piate 102 that is then refracted and reflected by the third inclined surface 118 and the fourth inclined surface 120. The light refracted by the third inclined surface 118 and the fourth inclined surface 120 is then reflected back by the reflector 402 to the combined light guide plate (i.e., combination of the first light guide plate 102 and the second light guide plate 04).

[0028] Similarly, in the first mode Mi operation of the backlight module 100, when the second light source 124 is activated, light generated from the second light source 124 may be reflected by the third inclined surface 1 18 and the fourth inclined surface 120, or refracted by the third inclined surface 1 8 and the fourth inclined surface 120 to exit the second light guide piate 104 that is then reflected back by the reflector 402 to the combined light guide plate (i.e., combination of the first light guide plate 102 and the second light guide piate 104). Further, the light reflected by the third inclined surface 118 and the fourth inclined surface 120 may be refracted and reflected by the first inclined surface 114 and the fourth inclined surface 118, The light refracted by the first inclined surface 114 and the second inclined surface 118 is then reflected back by the reflector 402 to the combined Sight guide plate {i.e., combination of the first iight guide piate 102 and the second Sight guide piate 104). in this case, the viewing angle of the backlight module 100 is the narrow viewing angie 130B and the viewing region is formed at opposite side as that of the viewing region formed when the first light source 122 is activated. The Sight with incident angle larger than the critical angie of the light guide plates 102 and 104 is reflected by the inclined surfaces {e.g., 114, 118, 118 and 120); otherwise the iight is refracted and exits the Sight guide pSates 102 and 104.

[0029] Further, in the second mode iv½ operation of the backlight module 100, both the first light source 122 and second Sight source 124 are activated. Light generated from the first light source 122 may be reflected by the first inclined surface 114 and the second inclined surface 116, or refracted by the first inclined surface 114 and the second inclined surface 116 to exit the first light guide plate 02 that is then refracted and reflected by the third inclined surface 118 and the fourth inclined surface 120. The iight refracted by the third inclined surface 1 8 and the fourth inclined surface 120 is then reflected back by the reflector 402 to the combined iight guide plate {i.e., combination of the first iight guide p!ate 102 and the second iight guide plate 104).

[0030] Similarly, Sight generated from the second light source 124 may be reflected by the third inclined surface 118 and the fourth inclined surface 120, or refracted by the third inclined surface 1 18 and the fourth Inclined surface 120 to exit the second iight guide piate 104 that is then reflected back by the reflector 402 to the combined iight guide piate (i.e., combination of the first light guide plate 102 and the second light guide plate 104). Further, the Sight reflected by the third inclined surface 18 and the fourth inclined surface 120 may be refracted and reflected by the first inclined surface 1 14 and the second inclined surface 116. The Iight refracted by the first inclined surface 114 and the second inclined surface 116 is then reflected back by the reflector 402 to the combined light guide plate (i.e., combination of the first light guide plate 102 and the second light guide plate 04). [0031] In this case, the combined effect of the lights generated by the first fight source 122 and the second light source 124 may lead to the wide viewing angle 30A of the backlight moduie 100.

Ϊ0032] Further, the Sight reflected by the reflector 402 to the combined light guide plate may exit the combined light guide plate and enter into the diffuser 202. The diffuser 202 evenly distributes the exited light onto the array of prism 204, Doing so may decrease th brightness of the Sight which may be enhanced by the array of prisms 204. The prisms 204 may aiiow the light to pass through it with enhanced brightness that is then made to fail on the display unit 302. In one example, the display unit may include a touch screen.

[0033] Further, the first light guid plate 102 and the second light guide plate 104, in different examples, may include different patterns formed thereon which are described in detail with reference to Figure 5 through Figure 1 1.

[0034] Fig. 5 illustrates an exploded view 500 of an example combined tight guide plat (i.e., a combination of the first iight guide plate 102 and the second light guide plate 104), In this example, the first inclined surface 114 and the second inclined surface 116 are connected via a third surface 502. Further, the third inclined surface 1 18 and the fourth inclined surface 120 may be connected via a fourth surface 504. In one example, the third surface 502 and the fourth surfac may be parallel to the first bottom surface 106 {as shown in Figure 1). in another example, the third surface 502 and the fourth surface 504 may be inclined to the first bottom surface 106 at an angSe.

[0035] Referring now to Fig. 6A which illustrates an exploded view 600 of an example combined light guide plate, in this example, the first inclined surface 114 may include semi-cylindrical cavities 602 formed thereon. In one example, the third inclined surface 1 18 may also include the semi-cylindrical caviiies 602 formed thereon (as shown in Fig. 6B).

[0036] Fig. 7 illustrates an exploded view 700 of an example combined light guide piate. In this example, the semi-cyiindrical cavities 802 may include reflective dots 702. The reflective dots 702 reflects the iight entered into the first tight guide 102 (if the reflective dots 702 are on the first inclined surface 114) or the tight entered into the second Sight guide plate 104 {if the reflective dots 702 are on the third inclined surface 118). In one exampie, the reflective dot may be a coating on the surface of the semi-cylindrical cavities 602,

[0037] Fig, 8 illustrates an exploded view 800 of an example combined light guide plate, in this example, the first inclined surface 114 may include semi- cylindrical cavities 602 formed thereon and the fourth Inclined surface 120 may include semi-cylindrical structures 802 protruding from the fourth inclined surface 120.

[00383 Fig. 9 illustrates an exploded view 900 of another exampie combined light guide plate, in this exampie, the first inclined surface 114 may include semi-cylindrical structures 802 protruding from the first inclined surface 114.

[0039] Referring now to Fig. 10 which illustrates an exploded view 000 of an example combined light guide plate. In this example, the first inclined surface 114 may include semi-cylindrical structures 802 protruding from the first inclined surface 14 and the semi-cyiindrica! structures 802 further includes reflective dots 702.

[0O4OJ Turning now to Fig.11 which illustrates another exploded view 1000 of an example combined light guide plate. In this example, the first inclined surface 1 14 and the fourth inclined surface 120 may include semi-cylindrical structures 802 protruding from the first inclined surface 1 14 and the fourth inclined surface 120, respectively.

[00413 Further, multiple combinations of the first light guide plate 102 and the second light guide piate 104 including semi-cylindricai structures 802, semi- cyiindrica! cavities 602, and the reflective dots 702 are described with reference to Fig. 5 to Fig. 11. However, any other combinations of the first light guide piate 102 and the second light guide plate 104 may aiso be possible to achieve the narrow viewing angle 130B and the wide viewing angie 130A.

[00423 It may be noted that the above-described examples of the present solution is for the purpose of illustration only. Although the solution has been described in conjunction with a specific example thereof, numerous modifications may be possible without materially departing from the teachings and advantages of the subject matter described herein. Other substitutions, modifications and changes may be made without departing from the spirit of the present solution. AH of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0043] The terms "include," "have," and variations thereof, as used herein, have the same meaning as the term "comprise" or appropriate variation thereof. Furthermore, th term "based on," as used herein, means "based at least in part on," Thus, a feature that is described as based on some stimulus can be based on the stimulus or a combination of stimuli including the stimulus.

[0044] The present description has been shown and described with reference to the foregoing examples. It is understood, however, that other forms, details, and examples can be made without departing from the spirit and scope of the present subject matter that is defined in the following claims.

Claims

WHAT IS CLAIMED IS:

1. A privacy backlight module comprising:

a first Sight guide plate having a first bottom surface, and a plurality of first prismatic structures formed on the first bottom surface, wherein each first prismatic structure comprising:

a first inclined surface and a second inclined surface connected to the first inclined surface, wherein the first inclined surface forming a first angle with the first bottom surface and the second inclined surface forming a second angle with the first bottom surface, wherein the first angle is smaller than the second angle;

a second light guide plate disposed above or below the first Sight guide plate and having a second bottom surface, a plurality of second prismatic structures formed on the second bottom surface, wherein each second prismaiic structure comprising:

a third inclined surface and a fourth inclined surface connected to the third inclined surface, wherein the third inclined surface forming a third angle with the second bottom surface and the fourth inclined surface forming a fourth angle with the second bottom surface, wherein the third angle is greater than the fourth angle:

a first light source disposed along a left surface of the first light guide plate; and

a second Sight source disposed along a right surface of the second Sight guide plate.

2. The privacy backlight module of c!aim 1 , wherein at least one of the first prismatic structure and the second prismatic structure comprises a plurality of semi-cylindrical structures protruding from at least one of the first inclined surface and the third inclined surface.

3. The privacy backlight module of claim 2, wherein the plurality of semi- cylindrical structures comprises reflective dots.

4. The privacy backlight module of claim 1 , wherein at least one of the firs prismatic structure and the second prismatic structure comprises a plurality of semi-cyiindrical cavities on at least one of the first inclined surface and the third inclined surface.

5. The privacy backlight module of claim 4, wherein the plurality of semi- cylindrical cavities comprises reflective dots.

8. The privacy backlight module of claim 1 , wherein the first light source and the second light source enable switching between a first mode and a second mode of the privacy backlight module, wherein one of the first light source and the second light source is activated when the privacy backlight module is operated in the first mode to provide a narrow viewing angle, wherein the first fight source and the second Sight source are activated when th privacy backlight module is operated in the second mode to provide a wide viewing angle,

7, A privacy backlight module comprising:

a first Sight guide plate having a first bottom surface, and a plurality of first prismatic structures formed on the first bottom surface, wherein each first prismatic structure comprising;

a first inclined surface, and a second inclined surface connected to the first inclined surface, wherein the first incSined surface forming a first angie with the first bottom surface and the second inclined surface forming a second ang!e with the first bottom surface, wherein the first angle is smaller than the second angie;

a second light guide plate disposed above or below the first light guide plate to form a combined light guide plate, the second Sight guide plate having a second bottom surface, a plurality of second prismatic structures formed on the second bottom surface, wherein each second prismatic structure comprising:

a third inclined surface and a fourth inclined surface connected to the third inclined surface, wherein the third inclined surface forming a third angle with the second bottom surface and the fourth inclined surface forming a fourth angle with the second bottom surface, wherein the third angle is greater than the fourth angle;

a first Iight source disposed along a left surface of the first light guid plate; a second light source disposed along a right surface of the second light guide plate;

a diffuser disposed on the combined Sight guide piate; and

a plurality of prisms disposed on the diffuser.

8. The privacy backlight module of claim 7, wherein at least one of the first prismatic structur and the second prismatic structure comprises a plurality of semi-cylindrical structures protruding from at least one of the first inclined surface and the third inclined surface.

9. The privacy backlight module of claim 8, wherein the plurality of semi- cyiindrica! structures comprises reflective dots.

10. The privacy backlight module of claim 7, wherein at least one of the first prismatic structure and the second prismatic structure comprises a plurality of semi-cylindrical cavities on at least one of the first inclined surface and the third inclined surface.

11. The privacy backlight module of claim 10, wherein the plurality of semi- cySindrical cavities comprises reflective dots.

12. The privacy backlight module of claim 7, wherein the first light source and the second light source emit lights that enter into the first light guide piate and the second iight guide plate, wherein the first Iight guide plate and the second Sight guide plate redirect the entered lights towards the plurality of prisms through the diffuser, and wherein each of the first iight source and the second iight source is a Sight-emitting diode (LED).

13, A dispiay device comprising:

a first Sight guide plate having a first bottom surface, and a plurality of first prssmaisc structures formed on the first bottom surface, wherein each first prismatic structure comprising:

a second light guide plate disposed above or below the first Sight guide plate to form a combined light guide plate, the second iight guide plate having a second bottom surface and a plurality of second prismatic structures formed on the second bottom surface, wherein each second prismatic structure comprising;

a first Iight source disposed along a left surface of the first light guide plate; a second light source disposed along a right surface of the second light guide plate;

a diffuser disposed on the combined Sight guide plate;

a plurality of prisms disposed on the diffuser; and

a display unit disposed on the plurality of prisms.

14. The display device of claim 13, wherein the privacy backlight module being operated in one of a first mode and a second mode to control viewing angle of the display device, wherein one of the first Iight source and the second light source is activated when the privac backlight module is operated in the first mode to provide a narrow viewing angle, wherein the first light source and the second light source are activated when the privacy backlight module is operated in the second mode to provide a wide viewing angle. 1 S. The display device of^■ claim 13, wherein the display unit is selected from the group consisting of liquid crystal display (LCD), organic light-emitting diode (OLED), polymer light-emitting diode (PLED), plasma display, and bi-stabie display.