The present application relates to a touch panel, especially to a capacitive touch panel to be used in combination with a display to form a so called touch screen for a user interface device of for example a mobile telephone.
Touch panels are known in the art for controlling devices via a user interface. The touch panel may be arranged on top of a display forming a so called touch screen. Such a touch screen provides a very intuitive way of operating the device. Information may be displayed on the display and in response to the information displayed on the display the user may touch the display for initiating actions or operations. The touch panel may work by detecting a change of capacity when the user approaches or touches the surface of the touch panel. Therefore, the touch panel may provide an array or grid of electrodes and a control unit may detect an approach of a finger of the user to a certain position on the touch panel by a change of capacitance of the electrodes. However, when the electrodes of the touch panel are arranged in close vicinity to the display, the electrically driven display and a control for driving the display may influence the electrodes such that the capacitive detection of the user touching the touch panel may be disturbed.
Therefore, there is a need to provide a more robust and reliable touch panel to be used for example in combination with a display, especially for consumer products like mobile phones.
According to the present invention, this object is achieved by a touch panel as defined in claim 1, a user interface device as defined in claim 12, and a mobile device as defined in claim 15. The dependent claims define preferred and advantageous embodiments of the invention.
According to an aspect of the present invention, a touch panel comprises a carrier panel, for example a transparent window panel made of glass or resin, and a first electrically conductive layer arranged on a surface of the carrier panel. The first electrically conductive layer comprises a first pattern of a plurality of electrically separated areas. The touch panel comprises furthermore an electrically isolating layer arranged on the first electrically conductive layer. The electrically isolating layer comprises openings providing access to at least some of the electrically separated areas of the first electrically conductive layer through the electrically isolating layer. The touch panel comprises furthermore a second electrically conductive layer which is arranged on the electrically isolating layer. The second electrically conductive layer comprises a second pattern comprising a plurality of electrically separated areas. The plurality of electrically separated areas of the second pattern comprises at least one bridging area which electrically couples at least two of the plurality of electrically separated areas of the first pattern through at least two of the openings of the electrically isolating layer. The plurality of electrically separated areas of the second pattern comprises furthermore a shielding area for electrically shielding the first pattern of the first electrically conductive layer. The shielding area is electrically isolated from the plurality of electrically separated areas of the first pattern of the first electrically conducive layer. The electrically separated areas of the first electrically conductive layer may comprise electrodes for detecting a capacitive change when a user is approaching the touch panel. The electrodes may be coupled to each other or wired to a connection area of the touch panel within the first electrically conductive layer or via the bridging areas in the second electrically conductive layer such that electrically isolated crossing points for wiring the electrodes may be accomplished. The shielding area of the second electrically conductive layer shields the electrodes from electrical disturbances such that the touch panel may be arranged in close vicinity to a display, for example a liquid crystal display without having the effect that the display disturbs the capacitive sensoring of the touch panel. As the shielding area is part of the second electrically conductive layer which may be anyway necessary for the bridging connections or crossing points, no additional separate shielding layer is needed. This reduces costs for the touch panel. Due to the shielding area the touch panel may be arranged directly on top of a front panel of the display and the carrier panel may comprise a front window made of glass or resin such that a minimum of components and layers is needed for a touch sensitive display. This may reduce not only the cost, but also installation space needed for accommodating the touch sensitive display in a mobile device, for example a mobile phone or a smart phone.
According to an embodiment, the shielding area covers essentially the whole first pattern apart from the at least one bridging area. The electrodes of the touch panel comprised in the first electrically conductive layer are typically arranged in a matrix or a grid. Therefore, only a few small bridging areas are necessary to connect the electrodes appropriately. The remaining space of the second electrically conductive layer is therefore available for serving as the shielding area. It is to be understood that the shielding area is electrically isolated from the bridging areas as well as from the electrodes of the first electrically conductive layer. Due to the large dimension of the shielding area in the second electrically conductive layer, an appropriate shielding of the electrodes in the first electrically conductive layer can be achieved.
According to a further embodiment, the first and the second electrically conductive areas are made of a visually transparent material. The visually transparent material may comprise for example indium tin oxide (ITO) or graphene. Thin layers of these materials absorb only a very small amount of light such that a display arranged behind the touch panel can be regularly read through the touch panel.
According to an embodiment, the plurality of electrically separated areas of the first pattern comprises a plurality of first fields arranged in rows and a plurality of second fields arranged in columns. Fields of the first fields in a common row are electrically coupled via connections within the first electrically conductive layer and fields of the second fields in a common column are electrically coupled via the at least one bridging area of the second electrically conductive layer. The first and second fields may serve as capacitance detecting electrodes. By arranging the first fields and the second fields in a matrix of rows and columns a position where a user touches the touch panel can be easily determined. Therefore, the electrodes or fields within one column have to be electrically coupled and the fields or electrodes within one row have to be electrically coupled. Therefore, crossing points may occur for wiring the rows and columns. Crossing conductive lines at the crossing points can be easily accomplished by a bridging area which is arranged across a line or connection within the first electrically conductive layer. Such a bridging area is also called “jumper”. The bridging area is electrically isolated from the connection or line within the first electrically conductive layer to be crossed by the electrically isolating layer. The bridging area is electrically coupled to the second fields through openings in the electrically isolating layer.
According to an embodiment, the first fields and the second fields each have a diamond shape. However, any other shape may be appropriate, for example a square shape or a circular shape.
The electrically isolating layer may be sandwiched between the first and second electrically conductive layers. Furthermore, the electrically isolating layer, the first electrically conductive layer, and the second electrically conductive layer may be arranged on a same side or surface of the carrier panel. The carrier panel may comprise a front window of for example a mobile device. The surface opposite to the surface on which the layers are arranged, may constitute an outer surface of the touch panel arrangement at an outside of the mobile device for being touched by a user. Therefore, the carrier panel does not only support the electrically conducting an isolating layers but provides also a protection for these layers. The carrier panel may comprise a transparent material such that a display which is arranged behind the carrier panel is visible through the carrier panel and the layers arranged on the carrier panel.
According to an embodiment, the openings of the electrically isolating layer are cutouts formed in the electrically isolating layer. However, the electrically isolating layer may be formed by printing an isolating material on the first electrically conductive layer, whereby the openings are not printed or protected from printing.
According to another aspect of the present invention a user interface device is provided. The device comprises a display configured to display information for a user on a display area of a front panel of the display, and a touch panel as described above. The touch panel may be arranged on the front panel of the display such that the second electrically conductive layer is arranged on the front panel. The shielding area may be coupled to a fixed electrical potential. Thus, electromagnetic fields from the display may be reliably shielded by the shielding area such that an operation of the touch panel is not influenced by an operation of the display.
According to an embodiment, the user interface device comprises furthermore a control unit coupled to the plurality of electrically separated areas of the first pattern and configured to determine based on a change of capacity of each of the plurality of electrically separated areas a position where a user approaches or touches the touch panel.
According to another aspect of the present invention, a mobile device is provided comprising the user interface as defined above. The mobile device may comprise a mobile phone, a personal digital assistant, a media player, or a navigation system.
Although specific features described in the above summary and the following detailed description are described in connection with specific embodiments and aspects, it is to be understood that the features of the embodiments and aspects my be combined with each other unless specifically noted otherwise.
The invention will now be described in more detail with reference to the accompanying drawings.
In the following, exemplary embodiments of the invention will be described in more detail. It has to be understood that the following description is given only for the purpose of illustrating the principles of the invention and is not to be taken in a limiting sense. Rather, the scope of the invention is defined only by the appended claims and is not intended to be limited by the exemplary embodiments hereinafter.
It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other unless specifically noted otherwise. Same reference signs in the various drawings and the following description refer to similar or identical components.
In the following, a structure of a touch panel will be described in more detail. The touch panel comprises a carrier panel, a first electrically conductive layer arranged on a surface of the carrier panel, an electrically isolating layer arranged on the first electrically conductive layer, and a second electrically conductive layer arranged on the electrically isolating layer. The structure of the single layers will be described in more detail in the following.
While exemplary embodiments have been described above, various modifications may be implemented in other embodiments. For example, the pattern of the fields 11-85 may comprise any suitable matrix or grid structure instead of the diamond-shaped fields shown in
Finally, it is to be understood that all the embodiments described above are considered to be comprised by the present invention as it is defined by the appended claims.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2012/000239 | 1/19/2012 | WO | 00 | 3/11/2014 |