Display device

Abstract

There is disclosed a privacy unit for a display assembly comprising: a first conducting layer, comprising: a conductive strip at each edge of the display, at least one conductive strip at a centre of the display, and at least one conductive strip between each conductive strip at each edge and the at least one conductive strip at the centre; and a plurality of resistive elements, each conductive strip between each conductive strip at the edge of the display and the at least one conductive strip at the centre being connected to an adjacent conductive strip by one of the resistive elements, the conductive strip at each edge of the display for connection to a first voltage, and the at least one conductive strip at the centre of the display for connection to a second voltage, a second conducting layer for connection to a third voltage; and a dielectric layer between the first and second conducting layers.

Description

[0001] DISPLAY DEVICE

[0002] The present application relates to a display device for generating a pixellated optical output (imparting information to a viewer in the form of text, images etc.) , and a method for controlling such a display device.

[0003] It may be desirable for the pixellated optical output to be readily viewable from a broad range of viewing angles on some occasions, but only readily viewable from a narrower range of viewing angles on other occasions.

[0004] There is provided an improved technique.

[0005] Examples are described in detail hereunder, by way of example only, with the reference to the accompanying drawings, in which:

[0006] Fig. 1 shows a representation of a cross section of an example privacy layer of a display device;

[0007] Fig. 2 shows a representation of a conducting layer of an example conducting device, comprising a plurality of cells;

[0008] Fig. 3 shows a representation of a conducting layer of an example conducting device, comprising a plurality of conductor strips ;

[0009] Figs. 4 (a) and 4 (b) shows a representation of a cross section of an example display device, illustrating the two outer most strips in a conducting layer as shown in the example of Fig . 3 ;

[0010] Figs. 5(a) and 5(b) shows a representation of a cross section of an example display device, illustrating two inner strips in a conducting layer as shown in the example of Fig. 3;

[0011] Figs. 6(a) and 6(b) shows a representation of a cross section of an example display device, illustrating two central strips in a conducting layer as shown in the example of Fig. 3; Fig . 7 illustrates a perspective view of the f irst and second conducting layers of Figs . 2 and 3 ;

[0012] Fig . 8 shows an example representation of a system for controlling the driver chips of Fig . 9 ;

[0013] Figs . 9 (a) and 9 (b) show an example representation of a display in public and privacy modes respectively .

[0014] There is provided a conducting layer for a display comprising : a plurality of conductive strips ; and a plurality of resistive elements , each of the plurality of conductive strips being connected to an adj acent conductive strip by one of the resistive elements , an outer one of the conductive strips for connection to a f irst voltage , and an inner one of the conductive strips for connection to a second voltage .

[0015] A voltage may be formed at each of the conductive strips between the inner and outer conductive strips in dependence on the f irst and second voltages and the connection of the resistance elements .

[0016] The inner one of the conductive strips may be a central strip , there may be provided a plurality of conductive strips either side of the central strip , an outer one of the conductive strips on each side of the central strip being for connection to the f irst voltage .

[0017] There is provided a privacy unit for a display assembly comprising : a f irst conducting layer , comprising : a conductive strip at each edge of the display, at least one conductive strip at a centre of the display, and at least one conductive strip between each conductive strip at each edge and the at least one conductive strip at the centre ; and a plurality of resistive elements , each conductive strip between each conductive strip at the edge of the display and the at least one conductive strip at the centre being connected to an adj acent conductive strip by one of the resistive elements , the conductive strip at each edge of the display for connection to a f irst voltage , and the at least one conductive strip at the centre of the display for connection to a second voltage , a second conducting layer for connection to a third voltage ; and a dielectric layer between the f irst and second conducting layers .

[0018] The privacy unit may further comprise a third conducting layer , and a refractive index changing material between the second and third conducting layers .

[0019] A plurality of openings may be formed in the second conducting layer .

[0020] There is provided a display assembly comprising : a backlight unit ; a privacy unit according to claim 4 or claim 5 ; and a display unit .

[0021] The privacy unit may be located between the backlight unit and the display unit .

[0022] The display unit may be located between the backlight unit and the privacy unit .

[0023] There is provided apparatus comprising the display assembly, and further comprising : at least one processor ; and at least one storage comprising instructions , the instructions conf igured to , with the at least one processor , cause the apparatus to control one or more properties of the display assembly .

[0024] In a privacy mode the instructions may be conf igured to apply the f irst , second and third voltages , and in a public mode the instructions are conf igured not to apply the f irst , second and third voltages .

[0025] The apparatus may further comprise a user controlled switch to control switching between the privacy mode and the public mode . There is provided a method of operating a display comprising : a f irst conducting layer , comprising : a conductive strip at each edge of the display, at least one conductive strip at a centre of the display, and at least one conductive strip between each conductive strip at each edge and the at least one conductive strip at the centre ; and a plurality of resistive elements , each conductive strip between each conductive strip at the edge of the display and the at least one conductive strip at the centre being connected to an adj acent conductive strip by one of the resistive elements , the conductive strip at each edge of the display for connection to a f irst voltage , and the at least one conductive strip at the centre of the display for connection to a second voltage , a second conducting layer for connection to a third voltage ; and a dielectric layer between the f irst and second conducting layers , the method comprising : selectively applying the f irst , second and third voltages .

[0026] The f irst , second and third voltages may be selectively applied in a privacy mode .

[0027] Applying the f irst , second and third voltages may create a dif ferent potential dif ference between dif ferent conducting strips of the f irst and the second conducting layers .

[0028] The method may further comprise a layer of refractive index changing material formed on the second conducting layer .

[0029] The second conducting layer may comprise a plurality of openings , wherein the dif ferent potential dif ference causes a dif ferent transmission of light in areas of the ref ractive index changing material above such openings .

[0030] The transmission of light may be dependent on the potential dif ference .

[0031] For areas of the refractive index changing material overlying portions of the second conducting layer where there are no openings , the potential dif ference may not control the transmission of light , and transmission of light is blocked .

[0032] The third voltage may control the voltage above the portions of the second conducting layer where there are no openings .

[0033] In areas of the refractive index changing material above openings in the second conducting layer , light may be substantially blocked at the edge of the display, light is substantially passed at the centre of the display, and the blocking / passing of light varies between the edge and the centre in proportion to the potential dif ference varying between a strip for the f irst conducting layer and the second conducting layer .

[0034] In the above , many dif ferent aspects have been described . It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above .

[0035] Various other aspects are also described in the following detailed description and in the attached claims .

[0036] In general , a representation of an example display system is described which is conf igured to switch between a privacy mode in which viewing angles to a display screen are restricted, and a public mode in which they are not .

[0037] Figs . 9 (a) and 9 (b) illustrate an example of a display apparatus including a display unit 60 , a so- called EPrivacy cell unit 62 , and a back light unit (BLU) unit 64 .

[0038] With reference to Fig . 9 (a) , in a public mode or wide angle mode , light rays from the BLU unit 64 pass through the EPrivacy cell unit 62 to the display unit 60 . The EPrivacy cell unit 62 is turned of f , and wide angle rays from the BLU unit are unaf fected in transmission to the display unit 60 . When turned of f , no electric voltage is applied across the EPrivacy cell , and a liquid crystal layer in the EPrivacy cell aligns to allow light to pass through the EPrivacy cell .

[0039] With reference to Fig . 9 (b) , in a privacy mode or narrow angle mode , light rays from the BLU unit 64 pass through the EPrivacy cell unit 62 to the display unit 60 . The EPrivacy cell unit 62 is turned on, and wide angle rays from the BLU unit are inhibited from transmission to the display unit 60 . When turned on, an electric voltage is applied across the EPrivacy cell , a liquid crystal layer in the EPrivacy cell changes orientation, and in an example blocks light from passing through an angle greater than 35° .

[0040] Figs . 9 (a) and 9 (b) show the EPrivacy cell unit below the display unit 60 , between the display unit 60 and the BLU unit 64 . The EPrivacy cell unit 62 can be placed above or below the display unit 60 depending on the type of display . For a liquid crystal display (LCD) the EPrivacy cell unit 62 can go either side of the display unit 60 . For an organic light emitting diode (OLED) display the EPrivacy cell 62 has to go above the display unit 60 .

[0041] The EPrivacy cell unit 62 may also be termed an ePrivacy unit of the display device . The unit 62 may also be termed a layer or a module of the display device .

[0042] Fig . 1 shows a representation of a cross section 10 of the EPrivacy cell unit 62 stack of a display device . The EPrivacy cell unit stack 10 comprises a f irst conducting layer 12 , for example an indium tin oxide ( ITO) layer , a dielectric layer 14 , a second conducting layer 16 , for example an indium tin oxide ( ITO) layer , a liquid crystal (LC) layer 18 , and a third conducting layer 20 , for example an indium tin oxide ( ITO) layer .

[0043] In the example of Fig . 1 , the second conducting layer 16 is shown as comprising a plurality of openings 30 , each comprising a perimeter gap 26 and a central conductive block 28 . This second conducting layer 16 will be described further with respect to Fig. 2, which illustrates an exemplary plan view of this layer.

[0044] In this exemplary illustration, Fig. 2 is representative of a full display, having 17 columns and 13 rows. These numbers are illustrative, and a display may have more or less rows and columns. In Fig. 2, there is illustrated a plurality of columns 36i to 3617, and a plurality of columns 38i to 3813. It should be noted that these rows and columns are the rows and columns of the EPrivacy cell unit 62. The display unit has a much greater number of rows and columns, consistent with the operation of the display .

[0045] The exemplary second conducting layer 16 is connected to a supply voltage V3. The supply voltage V3 is selectively applied to the second conducting layer 16.

[0046] The exemplary second conducting layer 16 has lettering or patterns formed across it. In the illustrated example, the lettering 'FE' is shown as an example in a repeated pattern across the second conducting layer 16. The gaps 30 in the second conducting layer 16 are provided to define this lettering or pattern. Preferably the lettering or pattern is formed of perforations formed in the conducting layer providing the outline of the shape, which is the gaps 26. The central portion 28 of these gaps may then still then be formed of the conducting layer material. The conducting layer material may electrically float in these gaps. The exemplary second conducting layer 16 may be patterned in any way desired.

[0047] In the example of Fig. 1, the first conducting layer 12 comprises a plurality of conductive strips 22, interconnected by a plurality of resistive elements 24. This first conducting layer will be described further with respect to Fig. 3.

[0048] As illustrated in Fig. 1, the first and second conducting layers oppose each other. Each strip 22 of the first conducting layer 12 aligns with a portion of the second conducting layer

[0049] 16.

[0050] Fig. 3 illustrates an exemplary plan view of the first conducting layer 12. In this exemplary illustration, Fig. 3 is representative of the full display, and the first conducting layer 12 comprises 17 strips denoted 22i to 22i7. The first conducting layer 12 may comprise more or less strips, and this number is illustrative. Note, the number of strips is independent of the number of columns in the display, which as noted above is in practice much grater than the number of strips.

[0051] Each strip is connected to an adjacent strip by a resistive element. In the example of 17 strips, there are provided 16 resistive elements denoted 24i to 2416. The resistive elements may be provided by a resistor network, via leads outs and an IC chip, or otherwise.

[0052] The two outermost strips 22i and 22I7are connected to a supply voltage Vi . The central strip 22g is connected to a ground voltage V2. The supply voltages Vi and ground voltage V2 are selectively applied, to selectively apply a potential difference between the strips 22i and 22g, and 22I7and 22g.

[0053] The described arrangement has an odd number of strips and a single middle strip. In alternatives there may be an even number of strips and two middle strips, and the two middle strips may be interconnected or independently connected to V2.

[0054] In the illustrated example, for each successive strip, starting from either edge, the resistive element 24i to 24is providing the connection between strips is offset. This may be concdiered to be a row position for descriptive purposes: the outermost strips may connected to their adjacent strips at row position '1' , and the centremost strip may connect to its two adjacent columns at row position '8' . The resistive elements do not need to be provided in such a pattern, and this is an illustrative example. As a result of the interconnection of each strip 22 by a resistive element 24, and the application of voltages Vi to the outermost strip and V2 to the centre strip, the voltage applied to each strip decreases from Vi to V2 moving from the outermost strip to the central strip, from each side. Each strip has a different voltage applied to it as a strip voltage, without needing a separate strip voltage supply connected to each strip.

[0055] The supply voltage V3 is typically the same as the supply voltage Vi . A typical value is 5V. The ground voltage is 0V.

[0056] The voltages of each conductor strip drop from 5V to 0V moving from the outer strip to the middle strip, whilst the voltage of the second conducting layer is at 5V. The potential difference between each strip of the first conducting layer and the second conducting strip thus changes and decreases, when moving from the outermost strip to the middle strip.

[0057] In a privacy mode of operation the supply voltages Vi and V3 are applied, and the ground voltage V2 is applied. The structure as shown in Figs. 1 to 3 is activated by these voltages in privacy mode to function so as to provide privacy. In a public mode of operation, the voltages Vi,V2,V3 are not applied, and privacy is not provided.

[0058] When in public mode, the letters 'FE' are not displayed on the display of the display device. When in privacy mode, and the voltages are applied to the two conducting layers (Vi, V2, V3) , the letters 'FE' are configured to be selectively displayed by the display, as will be discussed below, such that only the letters 'FE' can be seen at certain angles.

[0059] With reference to Figs. 4 to 6 the operation of the display device layer stack is further described. In these figures, the orientation of the LC crystal molecules is shown in different parts of the display under different operating conditions. For different parts of the display the orientation of the LC crystal molecules is shown with the display device in public mode (Vi,V2,V3 not applied) and the display device in private mode (Vi , V2 , V3 applied) .

[0060] Figs. 4 (a) and 4 (b) show a portion of the display stack of Fig. 1 including the two strips which are located at the edge of the display 22i and 222, and the associated interconnecting resistive element 24i.

[0061] Fig. 4 (a) illustrates the display in an 'off' operating condition, in public mode, when none of voltages Vi,V2,V3 are applied and thus no potential difference is applied across Vi and V2. The EPrivacy cell unit does not apply any restriction to the orientation of the liquid crystal molecules parallel to the surfaces of the layers throughout the liquid crystal layer 18 in this portion of the display. The orientation of the liquid crystal molecules is such that light passes through the liquid crystal layer 18 without restriction.

[0062] Fig. 4 (b) illustrates this portion of the display in an 'on' operating condition, in private mode, when voltages Vi,V2,V3 are applied and a potential difference is applied across Vi and V2.

[0063] The voltage applied to the strip 22i is Vi, and the voltage applied to the strip 222 will be less than Vi, although close to it, due to the gradual step down to a voltage of V2 in the middle strip 22g as discussed above. The potential between the strips 22i and 22g of the conducting layer 12 at Vi or close to Vi and the second conducting layer 16 at V3 is zero or substantially zero, as Vi applied to strip 121 is equal to V3 applied to the second conducting layer, and the voltage of the strip 22g will be close to the voltage applied to the strip 22i, albeit somewhat lower due to the voltage drop effect caused by the resistive element 24i. A small potential difference will exist between strip 222 and second conducting layer 16, but not enough for the liquid crystal molecules above the strip 22g to behave notably differently from the liquid crystal modules above the strip 22i. The orientation of the liquid crystal molecules in the liquid crystal layer 18 changes due to voltages Vi , V2 , V3 being applied . Molecules close to the f irst and second conducting layers remain substantially parallel to the stack layers , and molecules substantially central in the liquid crystal layer , substantially equidistant from the two conducting layers are orientated at an angle so they are no longer parallel to these layers . The angle or orientation is suf f icient to cause light to be substantially blocked from passing through the LC layer .

[0064] It can be seen that the orientation of liquid crystal molecules in portions of the liquid crystal layer 18 above the f irst and second strips 22i and 222 is substantially the same . Thus the blocking of light through the LC layer is substantially the same throughout the portion of the LC layer above the strips 22i and 222 .

[0065] In the outer region of the display, when privacy mode is enabled, light is substantially blocked by the EPrivacy cell unit .

[0066] Figs . 5 (a) and 5 (b) show a portion of the display stack of Fig . 1 including the two strips which are located approximately halfway between the edge and the centre , for example the strips 22s and 22g , and the associated interconnecting resistive element 245.

[0067] Fig . 5 (a) illustrates the display in an ' of f ' operating condition, in public mode , when none of voltages Vi , V2 , V3 are applied and thus no potential dif ference is appl ied across Vi and V2 . The orientation of the liquid crystal molecules is parallel to the surfaces of the layers throughout the liquid crystal layer in this portion of the display . The orientation of the liquid crystal molecules is such that light passes through the liquid crystal layer without restriction . The EPrivacy cell unit does not apply any restriction to the orientation of the liquid crystal molecules . Fig. 5(b) illustrates this portion of the display in an 'on' operating condition, in privacy mode, when voltages Vi,V2,V3 are applied and a potential difference is applied across Vi and V2.

[0068] The voltage applied to the strip 225is less than Vi, and the voltage applied to the strip 22s is further less than Vi, due to the step down to the voltage from Vi to V2between the strips 22i and 22g as discussed above. The potential difference between the strips 22s and 22g of the first conducting layer 12 and the second conducting layer 16 is greater than in Fig. 4 (b) . If the strips 22s and 22g are approximately midway from the outer edge to the centre of the display, then this potential difference will be approximately half the potential difference between Vi and V2. A larger potential difference will exist between strips 22s and 22g of the first conducting layer 12 and the second conducting layer 16, such that the liquid crystal molecules above the strips 22s and 22g are orientated differently in dependence on whether they are above a portion of the second conducting layer 16 without a gap, or above a portion of the second conducting layer 16 with a gap 38.

[0069] The orientation of the liquid crystal molecules in the liquid crystal layer 18 thus changes, but the changes are different to the example of Figs. 4 (b) . It can be seen from Fig. 5 (b) that the change in orientation of molecules above the openings 30 in the second conducting layer 16 is different to the change in orientation above other portions of the second conducting layer 16.

[0070] Above the openings 30, the molecules are moved from the original orientation of Fig. 5(a) less than molecules above other areas of the second conducting layer 16. The molecules above the openings 38 are oriented less, and are orientated by less of an angle than they are in the arrangement of Fig. 4 (b) . Above the second conducting layer outside of the gaps 30, the molecules are oriented the same as they are orientated in Fig. 4 (b) .

[0071] The angle or orientation of liquid crystal molecules above portions of the second conducting layer without a gap is sufficient to cause light to be substantially blocked from passing through the LC layer in these regions.

[0072] The angle or orientation of liquid crystal molecules above portions of the second conducting layer with a gap 30 is sufficient to cause light to be partially blocked from passing through the LC layer, but not substantially blocked, such that lights is partially transmitted in these regions.

[0073] In the region of the display between the outer edge of the display and the centre of the display, when privacy mode is enabled, light is substantially blocked in regions other than in regions where there is an opening in the second conductive layer, in which regions it is partially transmitted.

[0074] Figs. 6(a) and 6(b) show a portion of the display stack of Fig. 1 including the two strips which are located approximately at the middle of the display, for example the strips 22g and 22g, and the associated interconnecting resistive element 24g.

[0075] Fig. 6(a) illustrates the display in an 'off' operating condition, in public mode, when none of voltages Vi,V2,Vg are applied and thus no potential difference is applied across Vi and V2. The orientation of the liquid crystal molecules is parallel to the surfaces of the layers throughout the liquid crystal layer in this portion of the display. The orientation of the liquid crystal molecules is such that light passes through the liquid crystal layer without restriction. The EPrivacy cell unit does not apply any restriction to the orientation of the liquid crystal molecules.

[0076] Fig. 6(b) illustrates this portion of the display in an 'on' operating condition, in private mode, when voltages Vi,V2,Vg are applied and a potential dif ference is applied across Vi and V2.

[0077] The voltage applied to the strip 22g is V2, a ground voltage . The voltage applied to the strip 22g is slightly higher than V2, due to the step in the voltage from Vi to V2between the strips 22i and 22g as discussed above . The potential dif ference between the strips 22g and 22 g of the f irst conducting layer 12 and the second conducting layer 16 is more signif icant than in Fig . 4 (b) , and for strip 22g is the maximum potential dif ference . A larger potential dif ference will exist between strips 22g and 22g of the f irst conducting layer 12 and the second conducting layer 16 , such that the liquid crystal molecules above the second conducting layer are orientated dif ferently in dependence on whether they are above the second conducting layer 16 , or a gap 38 in the second conducting layer 16 .

[0078] The orientation of the liquid crystal molecules in the liquid crystal layer 18 changes , but the changes are dif ferent to the example of Figs . 4 (b) and 5 (b) . It can be seen from Fig . 6 (b) that the change in orientation of molecules above the openings 30 in the second conducting layer is dif ferent to the change in orientation above other portions of the second conducting layer .

[0079] Above the openings 30 , the molecules are substantially unmoved or unchanged from the original orientation of Fig . 6 (a) . The molecules above other areas of the second conducting layer 16 are moved similar to Figs . 4 (b) and 5 (b) .

[0080] This it can be seen that in the middle of the di splay for overlying portions of the second conducting layer 16 which are solid, the molecules of the overlying liquid crystal layer are changed in the same way, and substantially block the passage of light .

[0081] It can also be seen that in the middle of the di splay for overlying portions of the second conducting layer 16 which are above gaps 30 in the conducing layer, the molecules of the overlying liquid crystal layer are changed to substantially allow transmission of light in full. The angle or orientation of liquid crystal molecules above portions of the second conducting layer without a gap is sufficient to cause light to be substantially blocked from passing through the LC layer in these regions. The angle or orientation of liquid crystal molecules above portions of the second conducting layer with a gap 30 is sufficient to cause light to be substantially fully passed through the LC layer, such that light is substantially fully transmitted in these regions.

[0082] In general it can be seen that in privacy mode, for portions of the LC layer overlying gaps in the second conducting layer, the molecules are controlled in dependence on the applied potential difference between the strip of the first conducting layer and the associated portion of the second conducting layer. The smaller this potential difference, the more light is blocked, and the larger this potential difference, the more light is passed.

[0083] For other portions of the LC layer (not overlying gaps in the second conducting layer) , the molecules are controlled to substantially block light regardless of the potential difference .

[0084] In this way, transmission of light can be controlled in any portion of the display by controlling this potential difference.

[0085] By providing the first conductive layer as strips, a different voltage can be applied to each part of the first conductive layer, to provide a different potential difference in different regions. This potential difference can be stepped up from the edge of the display to the centre of the display.

[0086] In general, the larger the potential difference between the conducting layers (i.e. the difference in the voltage) the bigger the difference in light transmission. However once the voltage goes beyond a certain threshold, which may be in the range of -2--5V, then the light blocking effect may drop off again. Any given implementation may be designed to provide the best optical characteristics, which may involve controlling the maximum potential difference at the centre of the display so it does not exceed such a threshold.

[0087] The voltage V3 always controls the voltage above where there are no openings in the second conducting layer. The consideration of potential difference only has an effect in the portions of the second conducting layer where openings are provided .

[0088] By the provision of resistive elements joining the outermost and middle strip, a potential only needs to be applied to the outer strips and one or more central strip, and the remaining strips can take a voltage by virtue of the connection of the resistive elements.

[0089] Thus, with the voltages applied, the outer portions of the display, in which the outer strips are allow the display of the 'FE' letters whilst blocking transmission from the BLU unit, whilst in the middle portion of the display, in which the middle strips are provided, the display due to the BLU unit will be apparent, and the display of the letters 'FE' not visible. Between the middle and outer portions of the display, the display of the letters 'FE' fades from a maximum to a minimum.

[0090] This is partially illustrated with respect to Fig. 7. Fig. 7 illustrates the exemplary first 12 and second 16 conducting layers 12 and 16 in perspective view, with the connections to the voltages Vi,V2,V3 shown. For ease of illustration, Fig. 7 does not show the display originating from the BLU unit. Effectively Fig. 7 shows that in the central portion of the display the EPrivacy cell unit does not impact is on display transmission, whilst at the outer portions it does. When viewed straight on at the centre of the display a user will see the displayed content. When viewed at an angle, a user will see the 'FE' lettering.

[0091] Fig. 8 shows an example of a system for controlling the generation of the voltages Vi,V2,V3, to control the operation as described above. The system includes a user operable switch 50, a processor 52, a memory 35, and a controller 56, which generated the voltages Vi,V2,V3.

[0092] The processor 52 operates on the basis of computer program code stored in the memory 54 to control the controller 56.

[0093] Based, for example, on an input from the user operable switch 50, fed into the processor 52, the processor 52 controls the controller 56 to operate in a small viewing angle range mode (privacy mode) or in a larger viewing angle range mode (shared viewing mode) . In the small viewing angle range mode (privacy mode) the voltages Vi,V2,V3 are generated.

[0094] The processor 50 may be a single processor or a plurality of processors of one or more types . Components of the at least one processor 50 may be implemented using suitably programmed hardware, e.g. in the form of circuitry. The at least one processor may include a central processing unit (CPU) , a graphics processing unit (GPU) and / or a neural processing unit (NPU) , which may be referred to as a neural network accelerator.

[0095] The above-described techniques can provide good image blocking at angles great than about 45 degrees, without significant reduction in image quality (e.g. image luminance) for the primary viewer / user.

[0096] The above-described techniques can provide privacy at wide angles. For example, the above-described techniques can provide a high privacy performance measured by a ratio of brightness at 45° when public / private of 5:1 or higher, and more particularly 10:1 or higher . The above-described techniques can achieve good privacy mode operation without signif icant reduction of the on-axis performance (e . g . haziness , brightness and image clarity etc . ) of the display for the primary user .

[0097] The above-described techniques are suited to application also to curved displays .

[0098] An automated switch may replace or work in tandem with the user controlled switch, so for example a privacy mode can be automatically activated . A privacy mode may be automatically activated based on detection of , for example , a particular application being selected by a user .

[0099] In this description, reference is made to the EPrivacy cell layer including a liquid crystal layer . In general , this layer may be a layer of refractive index changing material , or a layer of material having controllable optical properties .

[0100] In addition to any modif ications explicitly mentioned above , it will be evident to a person skilled in the art that various other modif ications of the described examples may be made .

[0101] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features , to the extent that such features or combinations are capable of being carried out based on the present specif ication as a whole in the light of the common general knowledge of a person skilled in the art , irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims . The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features .

Claims

CLAIMS1 . A conducting layer for a display comprising : a plurality of conductive strips ; and a plurality of resistive elements , each of the plurality of conductive strips being connected to an adj acent conductive strip by one of the resistive elements , an outer one of the conductive strips for connection to a f irst voltage , and an inner one of the conductive strips for connection to a second voltage .2 . The conducting layer of claim 1 , a voltage being formed at each of the conductive strips between the inner and outer conductive strips in dependence on the f irst and second voltages and the connection of the resistance elements .3 . The conducting layer of claim 1 , the inner one of the conductive strips being a central strip , there being provided a plurality of conductive strips either side of the central strip , an outer one of the conductive strips on each side of the central strip being for connection to the f irst voltage .4 . A privacy unit for a display assembly comprising : a f irst conducting layer , comprising : a conductive strip at each edge of the display, at least one conductive strip at a centre of the display, and at least one conductive strip between each conductive strip at each edge and the at least one conductive strip at the centre ; and a plurality of resistive elements , each conductive strip between each conductive strip at the edge of the display and the at least one conductivestrip at the centre being connected to an adjacent conductive strip by one of the resistive elements, the conductive strip at each edge of the display for connection to a first voltage, and the at least one conductive strip at the centre of the display for connection to a second voltage, a second conducting layer for connection to a third voltage; and a dielectric layer between the first and second conducting layers.

5. A privacy unit for a display assembly according to claim 4, further comprising a third conducting layer, and a refractive index changing material between the second and third conducting layers .

6. A privacy unit for a display assembly according to claim 4 or claim 5, a plurality of openings being formed in the second conducting layer.

7. A display assembly comprising: a backlight unit; a privacy unit according to claim 4 or claim 5; and a display unit .

8. The display assembly according to claim 7 when the privacy unit is located between the backlight unit and the display unit.

9. The display assembly according to claim 7 when the display unit is located between the backlight unit and the privacy unit.

10. Apparatus comprising the display assembly of any one of claims 7 to 9, and further comprising: at least one processor; and at least one storage comprising instructions, the instructions configured to, with the at least one processor,cause the apparatus to control one or more properties of the display assembly.

11. The apparatus according to claim 10, wherein in a privacy mode the instructions are configured to apply the first, second and third voltages, and in a public mode the instructions are configured not to apply the first, second and third voltages.

12. The apparatus of claim 11, further comprising a user controlled switch to control switching between the privacy mode and the public mode.

13. A method of operating a display comprising: a first conducting layer, comprising: a conductive strip at each edge of the display, at least one conductive strip at a centre of the display, and at least one conductive strip between each conductive strip at each edge and the at least one conductive strip at the centre; and a plurality of resistive elements, each conductive strip between each conductive strip at the edge of the display and the at least one conductive strip at the centre being connected to an adjacent conductive strip by one of the resistive elements, the conductive strip at each edge of the display for connection to a first voltage, and the at least one conductive strip at the centre of the display for connection to a second voltage, a second conducting layer for connection to a third voltage; and a dielectric layer between the first and second conducting layers, the method comprising: selectively applying the first, second and third voltages.

14. The method of claim 13, wherein the first, second and third voltages are selectively applied in a privacy mode.

15. The method of claim 13 or claim 14, wherein applying the first, second and third voltages creates a different potential difference between different conducting strips of the first and the second conducting layers.

16. The method of claim 15 further comprising a layer of refractive index changing material formed on the second conducting layer.

17. The method of claim 16, the second conducting layer comprises a plurality of openings, wherein the different potential difference causes a different transmission of light in areas of the refractive index changing material above such openings .

18. The method of claim 17, the transmission of light is dependent on the potential difference.

19. The method of claim 17 or claim 18, for areas of the refractive index changing material overlying portions of the second conducting layer where there are no openings, the potential difference does not control the transmission of light, and transmission of light is blocked.

20. The method of claim 18, the third voltage controls the voltage above the portions of the second conducting layer where there are no openings .

21. The method of any one of claims 18 to 20, in areas of the refractive index changing material above openings in the second conducting layer, light is substantially blocked at the edge of the display, light is substantially passed at the centre of the display, and the blocking / passing of light varies between the edge and the centre in proportion to the potential difference varying between a strip for the first conducting layer and the second conducting layer.22

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