Method of backlighting a display panel and an apparatus therefor

0001The present invention relates to backlighting a display panel, and is particularly directed to using reflected sunlight to backlight the a display panel of an automated teller machine (ATM).

0002Many types of display panels having viewable display screens are known. Some display panels, such as a liquid crystal display (LCD) panel, require backlighting to enable a person viewing the display screen of the display panel to see information appearing on the display screen. Typically, a light source such as an energizable incandescent bulb is located behind the LCD panel which, when energized, enables the person to view information appearing on the display screen of the LCD panel.

0003When the LCD panel is used in an environment which has bright sunlight, it may be difficult to read information appearing on the display screen since the light source behind the LCD panel may not be of sufficient intensity to contrast the brightness of the sunlight. However, the use of a light source of increased intensity is undesirable as level of heat generated by the source and its power consumption will also increase. The generation of excessive heat may lead to an overheating condition.

0004It is an object of the present invention to provide a manner of backlighting a display panel in a sunny environment in which the above mentioned difficulties are substantially eliminated.

0005In accordance with one aspect of the present invention, there is provided a method of backlighting a display panel having a back side and a front side to enable the front side of the display panel to be viewed comprising the steps of directing sunlight behind the display panel, reflecting the sunlight directed behind the display panel towards the back side of the display panel to illuminate the back side of the display.

0006In a preferred embodiment, the reflected sunlight is focused towards the back side of the display panel.

0007In accordance with another aspect of the present invention there is provided a display panel system comprising a display panel having a back side and a front side, window means for directing sunlight behind the display panel and reflecting means located behind the display panel for reflecting the sunlight towards the back side of the display panel such that the reflected sunlight backlights the display panel to enable the front side of the display panel to be viewed.

0008An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which <ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 is a perspective view of an automated teller machine (ATM) embodying a display panel system constructed in accordance with the present invention;</li><li>Fig. 2 is a block diagram representation of the ATM of Fig. 1; and</li><li>Fig. 3 is a schematic illustration of a sectional view taken approximately along line 3-3 of Fig. 1.</li></ul>

0009With reference to Fig. 1, an automated teller machine (ATM) 10 comprises a user interface in the form of a front panel 12. The front panel 12 includes a card reader 14, a key pad 16, a cash dispenser 18, a liquid crystal display (LCD) panel 20 having a display screen 21, and a receipt printer 22. Each of the card reader 14, the cash dispenser 18 and the receipt printer 22 have slots located on the front panel 12 of the ATM to allow insertion of a user's identifying card 26 at the commencement of a transaction and delivery of currency notes and a receipt to the customer 24 at the termination of a transaction, respectively.

0010When the customer 24 inserts the user's identifying card 26 into the slot of the card reader 14, data contained on the card is read. The customer 24 is then prompted on the display screen 21 of the LCD panel 20 to enter a personal identification number (PIN) via the key pad 16. After the correct PIN is entered, menus are displayed on the display screen 21 to enable the customer 24 to carry out the desired transaction. After the transaction is completed, currency may be dispensed through the slot of the cash dispenser 18 and 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, a memory unit 34 connected via bus line 36 to the processor unit 32 and a register unit 38. 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 LCD panel 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 screen 21 of the LCD panel 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 nonvolatile RAM. Suitable microcomputers and memories are readily available in the marketplace. Their structure and operation are well known and, therefore, will not be described.

0012As shown in Figs. 1 and 3, a transparent non-reflective window 60 surrounds the outer periphery of the LCD panel 20. A lens system 64 is located behind the LCD panel 20 and a parabolic shaped mirrored surface 66 is located behind the lens system 64.

0013A light source 68 such as an incandescent bulb is located between the lens system 64 and the mirrored surface 66, as shown in Fig. 3. When energized, the light rays of light source 68 (represented by arrows 62 in Fig. 3) are directed towards the lens system 64 which focuses the light rays 62 and directs the focused light rays towards the back side of the LCD panel 20 to provide backlighting for the LCD panel 20.

0014In accordance with the present invention, incoming sunlight (represented by arrows 72 in Fig. 3) is transmitted through the transparent non-reflective window 60 surrounding the the LCD panel 20. The dimensions and position of the mirrored surface 66 behind the LCD panel 20 are such that the sunlight transmitted through the window 60 (represented by arrows 74 in Fig. 3) is received by the mirrored surface 66 and is reflected therefrom. The reflected rays of sunlight (represented by arrows 76 in Fig 3.) are directed towards the lens system 64 which focuses the reflected sunlight rays 76 and directs the focused light rays (represented by arrows 78 in Fig. 3) towards the back side of the LCD panel 20. It should be apparent that the focused light 78 directed towards the back side of the LCD panel 20 is a combination of light originating from the light source 68 and light originating from the incoming sunlight 72. The focused light originating from the incoming sunlight 72 supplements the light originating from the light source 68 to increase the backlighting intensity of the LCD panel 20 so as to enable the front side of the display panel to be viewed with improved contrast.

0015A number of advantages result from using incoming sunlight 72 to provide increased backlighting intensity for the LCD panel 20. For example, a light source 68 of increased intensity is not required in sunny conditions since light rays originating from the incoming sunlight 72 are used to supplement the light rays originating from the light source 68. Hence, the problems of increased power consumption and heat generation during operation of the increased intensity light source 68 are eliminated.

0016Although the foregoing describes a system in which the light source 68 is also used to provide backlighting for the LCD panel 20, it is conceivable that the light rays originating from the incoming sunlight 72 may provide sufficient backlighting for the LCD panel 20 such that the light source 68 may not always be required to be energized.

0017It should also be appreciated that the specific construction and use of the display panel may vary.