The invention relates to touch panels, particularly to flexible flat cables (FFC) of touch panels for signal transmission.
Touch panels have been widely applied in various electronic devices to become an important element of human-machine interface. A touch panel includes a transparent substrate. A touch sensor is disposed on the substrate. A central portion of the touch sensor is configured to be a touch sensing area. A circuit area is arranged around the touch sensing area. The circuit area is provided with signal wires connected to the touch sensing area. A connecting portion with contacts is disposed in the circuit area to electrically connect the signal wires. The connecting portion can be adhered with a flexible flat cable (FFC) to make electric connection. When assembling, the touch panel is superposed on the front of an LCD or LCM, and the FFC is attached on the back of the LCD or LCM.
However, current electronic devices always trend lighter and thinner. Especially in the design of display, a screen-to-body ratio is required higher and higher. To satisfy this requirement, the circuit area around the touch panel must be reduced. This causes that a layout space of the signal wires is seriously lowered and that an area of the connecting portion also becomes smaller. As a result, accuracy and difficulty of the manufacturing process becomes higher and the yield rate becomes lower. Also, such a connecting portion and an FFC may be connected with bad accuracy and adhesion. The more the number of the signal wires is, the more serious such a problem is.
An object of the invention is to provide an assembling structure of flexible flat cable of touch panel, which can reduce a width of the bezel portion of a touch panel.
Another object of the invention is to provide an assembling structure of flexible flat cable of touch panel, which can lower manufacturing costs and accuracy and increase reliability of production.
To accomplish the above object, the assembling structure of flexible flat cable of touch panel of the invention includes a transparent substrate, a transparent touch sensor and a flexible flat cable (FFC). The transparent substrate has a visible area and a shaded area which is around the visible area. The transparent touch sensor has touch sensing units arranged in a matrix and located within the visible area. Each of the touch sensing units is connected to a contact of a connecting port in the shaded area. The FFC is connected to the connecting port. The FFC includes a flexible insulative film and flat copper foil wires parallelly arranged on the flexible insulative film at regular intervals. All contacts of the connecting port are arranged at regular intervals. A distance between adjacent two of the contacts is the same as that of the copper foil wires. Each of the copper foil wires is electrically conducted to one of the contacts with adding an ACF.
In the invention, the FFC is composed of two flexible films and copper foil wires therebetween.
The invention further includes a bridging port located in the shaded area. The bridging port is provided with bridging points. Each bridging point is electrically connected to one of the touch sensing units, the bridging port is covered by an insulative film adhered on the substrate, the insulative film is provided with through holes corresponding to the bridging points, the insulative film is provided with bridging wires between two adjacent through holes, thereby all of the bridging points on an axis line are electrically connected to each other and then connected to the contact of the connecting port.
In the invention, the touch sensor is a projected capacitive touch sensor, the touch sensor are disposed on an upper surface of the visible area of the substrate, the touch sensor is composed of sensing columns, each of the sensing columns includes a sensing electrode and a plurality of driving electrodes, the sensing electrode and driving electrodes are arranged in an interlaced manner, each driving electrode is electrically connected to one of the bridging points in the bridging port, and each sensing electrode is electrically connected to one of the contacts in the connecting port.
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The invention may also be applied to resistive touch panels or electromagnetic touch panels. Additionally, in the above embodiment, the signal wires 27 of the touch sensor 2 are aggregated into the connecting port 4. However, in actual applications, the connecting port 4 may be more than one in number and they can be individually connected with respective FFCs.
Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and the scope of the present invention. Accordingly, the foregoing description is by way of example only and is not intended to be limiting. The present invention is limited only as defined in the following claims and the equivalents thereto.