Method of controlling viewability of a display screen and a device therefor

0001The present invention relates to controlling viewability of a display screen of a display system, and is particularly directed to controlling a liquid crystal display (LCD) panel device to control viewability of information on a display screen of a display system to provide privacy of viewing.

0002A typical display screen of a display system, such as a cathode-ray-tube (CRT) display, is viewable by a person in front of the display screen. In some applications of the CRT display, it is desirable to provide as wide a viewing angle as possible in front of the display screen. For example, it is usually desirable to provide as wide a viewing angle as possible in front of the display screen of a CRT display of a television set.

0003There are also applications of the CRT display in which it is desirable to limit the viewing angle in front of the display screen to provide privacy of viewing. As an example, it is desirable to limit the viewing angle in front of the display screen of the CRT display of an automated teller machine (ATM). One known way to limit the viewing angle in front of the display screen of the CRT display is to connect louvers around the periphery of the display screen. Another known way to limit the viewing angle in front of the display screen of the CRT display is to place a mechanical-type filter over the display screen.

0004USA 5,059,957 discloses a CRT display system for a vehichle, which includes control means to control the transmission factor of a liquid crystal panel so as to limit the viewing angle of the display. The transmission factor of the display screen and therefore the viewing angle is dependent upon the voltage applied to the liquid crystal display. Display of the image information provided on the CRT for the driver is controlled according to the running of the vehicle and/or the ambient light levels within the vehicle.

0005It is an object of the present invention to provide a way by which the viewing angle of a display screen is readily adjustable.

0006In accordance with one aspect of the present invention there is provided a display system comprising a display screen for displaying information; <ul id="ul0001" list-style="none" compact="compact"><li>a liquid crystal display (LCD) panel located in a position adjoining the display screen; and</li><li>control means for controlling the liquid crystal display panel to selectively define a viewing angle within which information on a portion of the display screen is viewable through the liquid crystal display panel characterized in that the liquid crystal display panel includes a plurality of energizable, substantially parallel segments which are spaced apart from each other, each segment being formed by a pair of electrodes.</li></ul>

0007In accordance with another aspect of the present invention, there is provided a method of controlling viewability of information on the display system as claimed in any of claims 1 to 6 the method comprising controlling the liquid crystal display panel to selectively define the viewing angle within which information on the screen is viewable through the liquid crystal display panel by selectively energizing some of said plurality of segments by applying a voltage to the pair of electrodes corresponding to each of the segments to be energized.

0008An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which: <ul id="ul0002" list-style="none" compact="compact"><li>Fig. 1 is a perspective view of an automatic teller machine (ATM) embodying the present invention;</li><li>Fig. 2 is a block diagram representation of the ATM of Fig. 1;</li><li>Fig. 3 is a sectional view, taken approximately along line 3-3 of Fig. 1, showing a liquid crystal display (LCD) panel device in contact with a display screen;</li><li>Fig. 4 is a view looking in the direction of line 4-4 of Fig. 3 and showing certain LCD segments energized;</li><li>Fig. 5 is a sectional view taken approximately along line 5-5 of Fig. 4; and</li><li>Figs. 6-8 are views similar to Fig. 5 and showing different LCD segments energized; and</li><li>Fig. 9 is a view similar to Fig. 5 and showing the LCD panel device spaced apart from the display screen.</li></ul>

0009An automated teller machine (ATM) 10 embodying the present invention is illustrated in Fig. 1. The ATM 10 comprises a user interface in the form of a front panel 12 which includes or is associated with a card reader 14, a key pad 16, a cash dispenser 18, a CRT display 20, and a receipt printer 22. The modules comprising the card reader 14, the cash dispenser 18 and the receipt printer 22 are respectively associated with slots which are provided in the front panel 12 and which in Fig. 1 have the same reference numerals as the respective modules. Thus, the card reader 14 has a card slot through which a customer 24 can insert a user's identifying card 26 at the commencement of a transaction to be conducted by the customer 24. The cash dispenser 18 has a cash slot through which cash currency notes stored inside the ATM 10 can be delivered to the customer 24 during the transaction. The receipt printer 22 has a receipt slot through which a receipt of the transaction is delivered to the customer 24 at termination of the transaction.

0010When the customer 24 inserts the user's identifying card 26 into the card slot of the card reader 14, the card reader reads data contained on the card. The customer 24 is then prompted on the CRT to enter a personal identification number (PIN) via the key pad 16. After the correct PIN is entered, menus are displayed on the display 20 to enable the customer 24 to carry out the desired transaction. After the transaction is completed, the receipt printer 22 prints a receipt of the transaction and delivers the receipt through the slot of the receipt printer 22 to the customer 24.

0011Referring to Figs. 1 and 2, the ATM 10 further comprises a controller unit 30 which communicates with components of the front panel 12. The controller unit 30 includes a processor unit 32, and a memory unit 34 connected via bus line 36 to the processor unit 32. The processor 32 receives input signals on lines 42, 44 from the card reader 14 and the key pad 16, respectively, and provides output signals on lines 46, 48, 50 to the cash dispenser 18, the display 20 and the receipt printer 22, respectively, to control the amount of cash dispensed by the cash dispenser 18, the information displayed on the display 20 and the information printed by the receipt printer 22. The processor unit 32 may include a microcomputer, and the memory unit 34 may be non-volatile RAM. Suitable microcomputers and memories are readily available in the marketplace. Their structure and operation are well known and, therefore, will not be described.

0012In accordance with the present invention, as shown in Fig. 3, a liquid crystal display (LCD) panel device 70 adjoins a front surface 62 of a display screen 21 of the display 20. Preferably, the LCD panel device 70 lies in contact with the front surface 62 of the display screen 21. The LCD panel device 70 is located between the front surface 62 of the display screen 21 and the customer 24 viewing the front surface 62 of the display screen 21, as shown schematically in Fig. 3. Preferably, the LCD panel device 70 overlies the entire viewing area of the display screen 21. Lighting from the display screen 21 of the display 20 provides backlighting to the LCD panel device 70.

0013The LCD panel device 70 includes two planar pieces of material 72, 74 and liquid crystal fluid 76 which is sandwiched between the two planar pieces of material to provide an encapsulated structure. Each of the planar pieces 72, 74 comprises transparent material such as clear glass or clear plastic. The LCD panel device 70 includes a plurality (hundreds) of energizable vertical segments 80 which are spaced apart from each other, as best shown in Figs. 4 and 5. The regions between adjacent vertical segments are transparent and are designated with reference numeral 82. The thickness of each of the vertical segments 80 and the transparent regions 82 between adjacent vertical segments are shown exaggerated in the Figures for purposes of illustration.

0014For each vertical segment 80, a pair of electrodes (not shown) is connected across the two planar pieces of material 72, 74 in the vicinity of the particular vertical segment. When no voltage is applied to the electrodes of the particular vertical segment 80, the segment is transparent. When a suitable voltage is applied to the electrodes of the particular vertical segment 80, the segment is opaque.

0015When none of the vertical segments 80 are energized (i.e., each vertical segment has no voltage applied thereto), all of the vertical segments are transparent. Accordingly, the display screen 21 is viewable through the entire LCD panel device 70. Each point on the display screen 21 has a viewing angle associated therewith. For example, a selectable point "P" (Figs. 4 and 5) on the display screen 21 would have a viewing angle "A" associated therewith if none of the vertical segments 80 are energized (i.e., if the entire display screen 21 is transparent). It should be noted that the select point "P" on the display screen 21 has been arbitrarily chosen and could have been anywhere on the display screen 21 within the transparent window 90 for purposes of explanation.

0016As shown in Figs. 4 and 5, the point "P" is viewable through a transparent window 90 (i.e., one of the transparent regions 82) defined between two corresponding adjacent energized (opaque) segments. The point "P" on the display screen 21 is viewable only within viewing angle "B". Viewing angle "B" is less than viewing angle "A" because the outermost peripheral lines of view in viewing angle "A" are blocked by the two adjacent opaque segments which define the the transparent window 90. Accordingly, the viewing angle associated with the point "P" on the display screen 21 is more limited than when all of the vertical segments 80 are transparent.

0017The actual thickness of each of the vertical segments 80 and the actual size of each of the transparent regions 82 between the vertical segments 80 will depend upon a number of factors including the degree of privacy desired and/or the resolution of the information appearing on the display screen 21. As an example, each of the vertical segments 80 in Fig. 6 is thicker than the vertical segments 80 shown in Fig. 5, such that the transparent regions 82 between adjacent vertical segments 80 shown in Fig. 6 are smaller than the transparent regions 82 between adjacent vertical segments 80 shown in Fig. 6. Accordingly, the point "P" on the display screen 21 in Fig. 6 is viewable only within viewing angle "C" which is less than viewing angle "B" shown in Fig. 5.

0018As another example, each of the vertical segments 80 in Fig. 7 has the same thickness as the vertical segments shown in Fig. 5, but are spaced further apart such that the transparent regions 82 between adjacent vertical segments 80 shown in Fig. 7 are larger than the transparent regions 82 between adjacent vertical segments shown in Fig. 5. Accordingly, the point "P" on the display screen 21 in Fig 7. is viewable only within viewing angle "D" which is greater than viewing angle "B" shown in Fig. 5.

0019As still a further example, each of the vertical segments 80 in Fig. 8 has the same thickness as the vertical segments shown in Fig. 5. The vertical segments 80 are spaced closer together such that the transparent regions 82 between adjacent vertical segments 80 shown in Fig. 8 are smaller than the transparent regions between adjacent vertical segments shown in Fig. 5. Accordingly, the point "P" on the display screen 21 in Fig. 8 is viewable only within viewing angle "E" which is less than viewing angle "B" shown in Fig. 5. Thus, the size of the transparent regions 82 between adjacent vertical segments and the thickness of the vertical segments 80 determine the viewing angle of a point ("P" in this example) on the display screen 21.

0020It is conceivable that the left and right portions of the LCD panel device 70 may have vertical segments which are separately energizable. Accordingly, the left portion of the LCD panel device 70 may be completely transparent while the right portion of the LCD panel device 70 may have opaque vertical segments, or vice versa. Moreover, the LCD panel device 70 may be divided into three or more portions in which each portion has vertical segments which are energizable separately from the vertical segments in each of the other portions.

0021Although the foregoing describes the LCD panel device 70 lying in contact with the display screen 21, it is contemplated that the LCD panel device 70 could have been spaced apart from the display screen as illustrated in Fig. 9. When the LCD panel device 70 is spaced apart from the display screen 21 as shown in Fig. 9, the viewing angles of all points on the display screen 21 are made smaller. For example, the viewing angle associated with the select point "P" in Fig. 9, is indicated as viewing angle "F" which is smaller than corresponding viewing angle "B" shown in Fig. 5. Also, if all vertical segments were to be transparent, the viewing angle in Fig. 9 would be angle "G" which would be smaller than viewing angle "A" shown in Fig. 5.

0022It should be apparent that a louvered-type of filter is provided across the display screen 21 by providing the LCD panel device 70 in accordance with the present invention. The LCD panel device 70 acts as an intelligent or programmable privacy screen for the display screen 21 of the display system 20. By programming spaced apart vertical terminals of the LCD panel device 70 to be opaque instead of transparent, the viewing angle of points on the display screen 21 can be varied and controlled. The programming feature of the LCD panel device 70 provides flexibility to easily change a particular viewing angle of the display screen 21 and to easily design custom privacy screens.

0023Moreover, it is conceivable that a more complex construction of the LCD panel device 70 could allow only select areas of the display screen 21 to have the privacy feature. These select areas may be localized anywhere on the display screen 21. In this connection, it should be noted that the pair of electrodes associated with a particular vertical segment could be made of separately energizable portions. Also, since an LCD panel device having only hundreds of energizable vertical segments (as opposed to thousands of segments which is typical of an LCD panel device for displaying information) is adequate to provide the features of the present invention, the costs associated with manufacturing such an LCD panel device is relatively low.

0024Although the foregoing describes an LCD panel device in which vertical segments are transparent when not energized and opaque when energized, it is contemplated that an LCD panel device in which vertical segments are opaque when not energized and transparent when energized, may be used instead. It is also contemplated that all the vertical segments of the LCD panel device 70 will be transparent (i.e., not energized) when the LCD panel device 70 is not being used as a privacy screen so that an advertising message on the display screen may be easily viewed. When a customer arrives at the ATM 10 to carry out a financial transaction, the LCD panel device 70 can be triggered at that time to provide the privacy screen feature. The presence of the customer at the ATM 10 may be detected using a proximity sensor or the like.