The present invention relates to a switch panel for use with a tablet or other computer device, and in particular to a wireless, touch operated switch panel, and to a touch switch panel which may be a computer keyboard, in which the defined switch or key areas are only visible by illumination when activated for use.

Background

Portable computing devices have led to an increase in the use of such devices when users are travelling, and touch screen tablet devices have become popular. Devices such as tablets and smartphones provide great convenience due to their portability, but the inconvenience of using an on-screen keyboard which consumes screen space has meant that external keyboards are commonly used when typing. Such keyboards are often wireless, and typically communicate with the device via Bluetooth. Wireless keyboards are also used with laptop computers, to provide a more comfortable full size keyboard to type on, and with desktop computers to reduce desktop cabling. Other kinds of switch panels may also be used with computing devices to provide inputs in various applications, as appropriate. Summary of the invention

The present invention provides a switch panel as claimed in claim 1 . In particular, the present invention provides a switch panel, or an integrated switch panel device, which may be a keyboard input device, comprising a touch- or proximity-responsive surface in which the switch or key areas are illuminated when activated for use, and preferably only visible when activated in this way. This arrangement can be used to provide a switch panel, possibly integrated into a surface such as a desk or seat-back tray, which is effectively secret, or otherwise unobtrusive, until it is lit up. This is typically achieved by backlighting the touch responsive surface. In one embodiment, the switch panel is a capacitive touch operated switch panel, powered from a single DC (e.g. 12V) supply, which uses preferably capacitive matrix or capacitive slider type switches to allow a standard switch panel or keyboard to be simulated and mapped by determining which slider and which position on the slider is touched by a user. The output may be via a standard Bluetooth connection, to provide communication with an external computing device such as a tablet.

References to a touch panel or touch responsive surface are intended to include the possibility that the panel or surface may be responsive to a user actuation which comprises not only physically touching the surface, but may also include the user (or typically the digit of a user) being positioned in close proximity to the surface without actually touching. In some arrangements, for example, the switch panel may be placed behind a window or other surface such that the user might actuate the switch panel by touching, or coming into close proximity to, the window, without actually touching the switch panel located behind it.

In an embodiment, the switch panel comprises a layer having a touch- or proximity- responsive surface and being patterned to indicate defined switch areas of the surface to a user; illumination means for illuminating the patterned layer; and output means for providing an output signal in response to a user interaction with one or more of the defined switch areas, wherein the switch panel is arranged to operate in: (i) an active state, in which the illumination means are arranged to illuminate the patterned layer so as to make the switch areas visible to the user; and (ii) a dormant state, in which the switch areas are substantially not visible to the user, and the output means are arranged to provide the output signal only when the switch areas are visible in the active state. The switch panel may be configured for use as an input device for an external computing device, e.g. as an external keyboard for a computer or portable device. This allows a switch panel in the form of a keyboard, which may for example be present in a desk top or other surface, to be used as an input device for a computer or tablet, etc, which the user brings to that location.

The outer surface of the switch panel may be a substantially continuous surface, to aid the effect of concealing the panel from the user, or otherwise rendering it unobtrusive, when it is not activated.

The invention allows a switch panel to be incorporated in, for example, a vehicle seat- back tray, or a desk surface which can also be used for other purposes, or in surfaces which constitute an area where a user might be using a tablet or other personal computing device, thereby providing a convenient external switch panel or keyboard for use with such a device, when required. The switch panel may be connected through a wired connection or docking connection, and activated/visible when connected, or is preferably wireless and connected via Bluetooth or other appropriate wireless standard. Alternatively, the switch panel device may be a standalone portable external switch panel or keyboard for a computing device, which illuminates when activated for use, to show the defined areas of the touch keys or switches, and may be wired or wireless. In another aspect, a switch panel device comprises a seat-back tray for a vehicle seat, the tray having an integral switch panel or keyboard as described above.

Brief description of the drawings

An embodiment of the invention will now be described, by way of example, with reference to the drawings, in which:

Figure 1 shows an exploded view of the components of a switch panel in accordance with an embodiment;

Figure 2 shows an exploded view of the switch panel of Figure 1 , and a switch panel surround;

Figure 3 shows a perspective view of the assembled switch panel in the form of a computer keyboard;

Figure 4 shows a side perspective view of the switch panel of Figure 3;

Figure 5 shows the assembled switch panel in the form of a computer keyboard with surround in an activated (illuminated) state;

Figure 6 shows the switch panel of Figure 5 in a dormant state, in which the key markings are not visible; and

Figure 7 shows in a schematic block diagram the components of the switch panel of an embodiment.

Detailed description of the invention

In a preferred embodiment, the present invention provides a capacitive touch 'secret until lit' switch panel, whose keys are not visible until the in-built illumination, e.g. backlight, is activated. The switch panel preferably provides a wireless connection to a computer device, e.g. a tablet, smartphone, laptop, desktop PC, etc, typically by means of a Bluetooth or other wireless connection. When employing such a wireless connection, the switch panel will pair with, and can be used as an input device for, any conventional computing device having the required connection capability, and the paired device would receive data from the switch panel and see it as a typical Bluetooth standard device, for example a standard Bluetooth keyboard or other switch panel.

Figure 1 shows the construction of an embodiment of a switch panel 10, in an exploded view. The switch panel comprises a 'secret til lit' (STL) graphic layer 102 consisting of a back printed transparent or tinted plastic. This layer is reverse printed with the images or legends which are intended to appear to the user when the backlight is activated, e.g. the switch areas making up the switch panel, or the key areas making up a keyboard. In other embodiments, the layer 102 may be provided with a pattern in other ways, for indicating the defined switch areas to the user, for example by moulding or etching the layer. In an embodiment in which the images or legends are printed, they may be printed using a transparent ink which is substantially invisible to the user when not illuminated, but is visible to the user when illuminated by the backlight or other illumination means.

The STL graphic layer 102 is bonded by an adhesive layer 104 to a light guide/diffuser layer 106. In the illustrated embodiment, the light guide/diffuser is formed as a single layer diffuser which includes an etched light guide, but the light guide and diffuser of this layer could equally be formed as two separate parts. The light guide/diffuser may be formed with a pattern corresponding to the switch areas by means other than etching, for example by moulding or printing the required pattern. The light guide/diffuser layer 106 is bonded to a printed circuit board (PCB) 1 12 by a further adhesive layer 108, which includes apertures 109 for allowing a peripherally located plurality of LEDs 1 10 to extend through the further adhesive layer 108 and into the light guide/diffuser layer 106 when the LEDs 1 10 are mounted on the PCB 1 12.

The graphic layer 102 may be provided with an opaque mask layer on its underside, to mask transmission of light in selected areas, so that light is only transmitted in or around the areas corresponding to the printed or otherwise patterned areas corresponding to the images or legends requiring illumination in the activated state. The mask layer may be further provided with a reflective layer arranged to reflect light from areas masked by the mask layer.

Where the panel is a capacitive touch panel, the layers described above are preferably arranged such that they do not affect the capacitance of the switch panel, and hence do not interfere with the touch or proximity detection. In the illustrated embodiment, a further PCB 1 16 forms a separate control board, and is affixed to PCB 1 12 by means of an adhesive layer 1 14. However, the control components may either be on separate PCB 1 16 or may be on-board PCB 1 12.

The STL graphic layer 102 may be flat (as shown) or curved, and the other layers can be shaped accordingly. For example, the PCB 1 12 and further PCB 1 16 may be a conventional rigid PCB or a populated plastic flexible PCB, and where the PCBs are required to take a shape that is not flat, they may be either rigid and shaped, or may be flexible. The PCB may also be replaced by any other form of circuit board, as appropriate.

The LEDs 1 10 may be arranged around the perimeter of the switch panel, as shown, or may be provided in other configurations in order to provide the necessary backlighting of the switch panel. When illuminated, the light from the LEDs is diffused and directed by the light guide/diffuser layer 106 in order to illuminate the graphic on the STL graphic layer 102, thereby making the defined switch/key areas of the switch panel visible to the user.

Figure 2 shows the switch panel 10 of Figure 1 , also in an exploded view, together with a switch panel surround 20. The switch panel 10 fits into the surround 20, to form an integrated switch panel device 30, such as an external computer keyboard device. The integrated switch panel device could be any type of product having an integrated switch panel which is not visible to the user until activated and backlit, and could be, for example, a seat-back or a seat-back tray on a train, aircraft or car seat, or a working surface such as a desk top or a table or tray. In one example, therefore, the switch panel could provide a computer keyboard integrated into such a seat-back tray, for use by a vehicle passenger with a separate portable computer device. Alternatively, the switch panel could be integrated into a case or cover, for example, for a tablet computer, so as to provide a keyboard for use with that device. The switch panel could also be used to provide controls for an apparatus, which are hidden until a user activates the panel.

Figures 3 and 4 show the assembled switch panel 10, including the layers 102, 106 and 1 12. Figure 3 illustrates the graphic layout of the switches, in this case keys of a computer keyboard, which is only visible to the user when the backlight is activated. In the view of the switch panel 10 shown in Figure 4, the control board 1 16 is also visible on the underside of the switch panel, and the side view of the switch panel in Figure 4 also shows how the LEDs 1 10 mounted on the PCB 1 12 are located so as to protrude into the light guide/diffuser layer 106.

Figures 5 and 6 show the switch panel 10 located in the switch panel surround 20 to form an integrated switch panel device 30, as described above. In Figure 5, the switch panel, in this case in the form of a computer keyboard, is shown in the activated state, where the backlight is activated and the keys are visible to the user. In Figure 6, the switch panel 10 is in a dormant state, in which the backlight is not activated, and the switch panel graphic on the STL graphic layer 102 is therefore not visible to the user. In this state, the integrated switch panel device 30 may simply be used as a tray table (for example, in the case where the switch panel is integrated in a seat-back tray), and touching the surface of the switch panel will not cause key strokes to be transmitted over Bluetooth or deplete the switch panel battery, where it is battery powered.

When the switch panel is activated, and the key areas are visible to the user, key strokes are detected using appropriate detection means. In this embodiment, capacitive touch detection may be used. The capacitive touch input technology may be provided in the PCBs 1 12 and 1 16 in a known manner, such as by using a programmable microcontroller matrix configuration, where X and Y directions are scanned for touch inputs using QTouch or capacitive touch technology to define input 'sliders'. The microcontroller may be, for example, an Atmel SAM D20 or D2x series microcontroller, or other similar device.

The use of the Atmel device, or similar programmable microcontroller, allows touch positions to be recognised on a particular set of sliders, where each slider represents an area of the switch panel. Sensing a touch on a slider or switch will allow the microcontroller device to interpret a location of the touch input between, for example, 0- 127 in the X or Y directions, which is subdivided between active and non-active areas representing the switches/keys and spaces between keys, in software. This allows touch inputs to certain areas to be disregarded, e.g. touches between keys or outside of the defined key areas.

Appropriate processing means are provided, e.g. on circuit board 1 16, to detect switch/key presses by a user, and to provide the necessary output to an external computing device. Once a switch/key press is identified it is output to the external device (e.g. tablet) via Bluetooth, or other suitable communication means. In other embodiments, the output from the switch panel is provided over a wired, e.g. USB connection. In one example, the control board 1 16 is formed by a small PCB approximately 18mm by 200mm, housing the control components, and is supplied by a nominal 12 Volt (9- 15V) supply. This control board may contain the components of the touch sensing circuit (e.g. the Atmel circuit) except for the touch sliders to which it may be connected by appropriate connection means. However, the physical location of the various components may be adapted as appropriate. The PCB(s) should contain all the necessary components to allow the input slider areas to be scanned, and the interpreted results output via the Bluetooth or other connection.

In a typical embodiment, the switch panel is in the form of a computer keyboard and is capable of interpreting detected key presses and outputting corresponding standard ASCII codes via a Bluetooth module to the paired device. The switch panel may also be provided with a suitable battery, such as a known rechargeable battery, or other power means. The processing means of the switch panel are preferably configured to enable the switch panel to pair to the external computing device, which can be activated on power up by making the switch panel visible over Bluetooth for a predetermined initial time period, such as 1 minute. In the present embodiment, the switch panel markings are not visible to the user until the backlight is activated, and so on power up the backlight may be illuminated for a short period, e.g. 10 seconds, to indicate that it has been activated. In one arrangement, the power supply to the backlight may be toggled by touching two areas of the switch panel surface which are not defined as keys, simultaneously for a short period, such as 3 seconds. In a preferred embodiment, key presses will not be transmitted via Bluetooth if the backlight is off (i.e. if the switch panel is not activated). This means that the surface of the switch panel, when the backlight is off and the key markings are therefore not visible, can be used for other purposes, e.g. where the switch panel is integrated into the surface of a seat back tray or desk, without the switch panel transmitting key presses or using battery power.

There is a requirement to simulate certain combinations of multiple key presses, since using this technology only one position on a slider can be identified at a time. In the case of a computer keyboard, for example, combinations of expected multiple simultaneous key presses such as 'shift' and a letter, or 'Caps Lock', therefore need to be on different sliders. The processing means should allow standard combinations to be monitored and communicated to the external computing device with which the switch panel is paired. The identification of a key press may allow an output to a haptic feedback device such as a piezo device or speaker which can provide a vibration of the unit for a fixed time per press, and may be operable or not in response to a user preference.

The switch panel may also be provided with LED key status indicators, such as 'Num Lock', 'Scroll Lock', 'Caps Lock' and/or 'Bluetooth active' indicators, and the software may toggle such indicators in response to the relevant keys being pressed. Figure 7 shows in a schematic block diagram the components of a switch panel of an embodiment. In one embodiment, the switch panel uses an Atmel D20 or D2x series processor with active touch, which is powered by a DC power supply. Optionally, the switch panel is provided with a battery, and charging capability. The backlight is typically also powered by the regulated DC supply (e.g. a 200mA supply) from the control board. The switch panel may be provided with an indicator block of LEDs which indicate the status of 'Caps Lock', 'Num Lock', etc, in the same manner as a conventional computer keyboard, when the switch panel is active and backlit. The switch panel may be provided with a sleep mode, in order to save battery power, or otherwise to revert to the inactive, dormant mode after a certain period of inactivity.

The switch panel may be provided with haptic feedback, as described above, and typically includes a Bluetooth output module, or other equivalent wireless communication module, where implemented as a wireless switch panel. However, the switch panel may also be provided having a wired connection, connecting to an external computing device either through a cable plugged into the computing device, or wired to a docking connection whereby the switch panel is connected to the computing device when the computing device is docked. Numerous modifications, adaptations and variations to the embodiments described herein will become apparent to a person skilled in the art having the benefit of the present disclosure, and the scope of the invention is limited only by the claims.