Patent Application
20170160854
1. Technical Field
The invention relates to input devices for portable computers, particularly to touchscreens.
2. Related Art
For inputting texts, touchscreen modules have been extensively applied in smartphones, tablets and laptop computers. Conventional touchscreens can detect a coordinate of the position which is being touched, so they can cooperate with the screen picture to input texts or make an operation. In some cases, such an operating mode may meet a difficulty, for example, a virtual key shown on a touchscreen may be unexpectedly activated because it merely needs a very light force or even does not need a force to apply thereon. In order to avoid such a problem, how to correctly detect a touching operation to a virtual key is the core. A currently known solution is to add a pressure sensor under the touchscreen, by which a force exerted on the touchscreen can be detected. As a result, a touching operation can be correctly determined.
U.S. Pat. No. 8,988,384 discloses a force sensor interface in a touch controller of a touch sensitive device, which includes one or more touch sensors and one or more force sensors. The touch controller can correctly determine a touch operation by associating a touch signal with a force signal. The touch sensitive device includes a rigid cover, under which the touch sensors and force sensors are arranged. The rigid cover will not be bent or deformed to trigger the force sensor. Such a force sensor is a strain gauge based upon a resistor bridge a shown in
An object of the invention is to provide a touch and pressure sensitive panel, which is easy to be manufactured. Thus its manufacturing cost can be effectively reduced.
Another object of the invention is to provide a touch and pressure sensitive panel, which is a flexible thin plate without any movable mechanism. Thus it will not reduce or damage a sealing effect of a product using it.
To accomplish the above objects, the touch and pressure sensitive panel of the invention includes:
a surface layer, being a flexible transparent sheet;
an insulative layer, being a flexible transparent sheet;
a first electrode layer, being a flexible transparent conductive film, sandwiched between the surface layer and the insulative layer, and having sensing electrodes covered by the surface layer;
a second electrode layer, being a flexible transparent conductive film, disposed under the insulative layer, and having driving electrodes, wherein the insulative layer is sandwiched between the first electrode layer and the second electrode layer to form a touch sensing structure;
a strain isolation layer, disposed under the second electrode layer, and having a property of elastic deformation
a third electrode layer, disposed under the strain isolation layer, and having sensing electrodes; and
a base layer, being a rigid transparent sheet, disposed under the third electrode layer;
wherein the sensing electrodes on the third electrode layer and the driving electrodes on the second electrode layer face each other and keep a gap therebetween, the strain isolation layer completely fill the gap, and the second and third electrode layers and the strain isolation layer constitute a touch pressure sensing structure.
Please refer to
The surface layer 10 is made of a transparent sheet material, such as an optical glass sheet. To make the surface layer 10 flexible, its thickness is about 0.4 mm. Also, the surface layer 10 may be further reinforced by a chemical or tempering process. Additionally, each of four corners of the surface layer 10 is formed with a chamfering 11 to prevent the surface layer 10 from peeling off.
The first electrode layer 20 is a flexible transparent conductive film, such as an ITO (indium tin oxide) conductive film, and is sandwiched between the surface layer 10 and the insulative layer 30. There are sensing electrodes 21 at regular intervals on the first electrode layer 20.
The insulative layer 30 is a flexible transparent sheet, for example, an optical glass plate or PMMA (polymethylmethacrylate) or COP (cyclo olefin polymers) thin plate with a thickness of about 0.1 mm. Alternately, the insulative layer 30 may select a dielectric material to improve a gain of touch signal.
The second electrode layer 40 is a flexible transparent conductive film, such as an ITO conductive film, and is disposed under the insulative layer 30. There are driving electrodes 41 at regular intervals on the second electrode layer 40. Preferably, an ITO conductive layer may be directly formed on each side of the insulative layer 30 in advance, and then an etching process is applied to form an electrode pattern.
The base layer 70 is a rigid transparent plate, such as an optical glass sheet with a thickness of about 0.2 mm. The rigid base layer 70 can provide support to the third electrode layer 60 to prevent from being bent by pressure. Usually, the invention is used for being disposed over a display (not shown), so the base layer 70 can be supported by the display on which the invention is placed. As a result, the base layer 70 will not be bent by normal pressure.
The third electrode layer 60 is a transparent conductive film, such as an ITO conductive film. There are sensing electrodes 61 at regular intervals on the third electrode layer 60. The third electrode layer 60 is disposed on the base layer 70 and under the second electrode layer 40 with a parallel gap D, which is about 150 μm.
The strain isolation layer 50 is formed by filling the space formed by the gap D with a transparent insulative material with a property of elastic deformation. The strain isolation layer 50 isolates the second and third electrode layers 40, 60. The strain isolation layer 50 will be deformed by pressure applied on the surface layer 10, its property of elastic deformation allows the electrodes 41, 61 to change their relative positions, for example, shortening a vertical distance between two opposite electrodes or changing a horizontal interval between two adjacent electrodes. When the pressure removes, the strain isolation layer 50 resumes to its original shape and restores relative positions between two opposite layers of electrodes 41, 61. The strain isolation layer 50 may select a material with a low index of refraction or an index of refraction near that of glass, such as an OCA (optical clear adhesive) or a dielectric material. When an OCA is adopted, it can further provide adhesion between the second and third electrode layers 40, 60. When a dielectric material is used, it can gain a touch signal of a touching operation.
The first electrode layer 20, the second electrode layer 40 and the insulative layer 30 constitute a touch sensing structure 100. Of course, the sensing electrodes 21 on the first electrode layer 20 and the driving electrodes 41 on the second electrode layer 40 can be separately electrically connected to a touch controller (not shown).
As shown in
The second electrode layer 40, the third electrode layer 60 and the strain isolation layer 50 constitute a touch pressure sensing structure 200. Of course, the driving electrodes 41 on the second electrode layer 40 and the sensing electrodes 61 on the third electrode layer 60 can be separately electrically connected to a touch controller (not shown).
Please refer to
In order to increase sensible capacitance between the second and third electrode layers 40, 60, the driving electrodes 41 and the sensing electrodes 61 can be formed into a grid shape with an interlacing arrangement as shown in
In the above embodiment, the touch sensing structure 100 is the same as the touch pressure sensing structure 200 in fundamental framework. Accordingly, the invention can be applied without changing currently existing capacitive touchscreens, even can be compatible to currently existing controllers for capacitive touchscreens. This can effectively save costs of development of a new component. Furthermore, the touch sensing structure 100 and the touch pressure sensing structure 200 commonly share the driving electrodes 41 on the second electrode layer 40. However, in another embodiment, a fourth electrode layer 90 can be further added between the second electrode layer 40 and the strain isolation layer 50 as shown in
It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.
