Many devices use touch screens or panels as a convenient and intuitive way for users to both view and enter information. Common applications include mobile phones, PDAs, ATMs, GPS navigation systems, electronic games, and computer interfaces, to name just a few examples. Touch screens allow a user to interact with the device by using a finger or stylus to touch objects displayed on a screen, such as icons, text, buttons, etc. In some applications, a user may also “write” and/or “draw” directly on a touch screen, such as in a PDA or other device that implements character recognition.
There are numerous technologies used to implement touch screens, including technologies that use the electrical property of capacitance to detect user inputs. A capacitive touch screen sensor is one type of sensor that generally operates by capacitive coupling through a transparent dielectric layer to a user's finger (or a stylus). This type of sensor typically includes a passive sensing circuit with multiple transparent electrodes, each producing an electric field across the touch sensitive area of the sensor. The capacitive sensing circuit may be adjacent to a transparent sensor substrate (e.g., glass or polymer). Other applications for capacitive touch sensors include non-transparent touch panels (e.g., laptop mouse pads). In these applications, the capacitive sensing circuit may be positioned adjacent to a non-transparent sensor substrate (e.g., an opaque polymer).
A touch near one or more electrodes of the sensing circuit may affect the electric field and create a signal that can be detected. A set of electrical connections are made between the sensing circuit and the detection electronics (e.g., a controller) that resolves the signals to determine the location of the touch on the sensor. The coordinates to the location may then be communicated to another processor such as a host computer for further processing.
Touch sensors utilizing one or more patterned sensing layers are often used to determine the coordinates of a touch with high accuracy, provided that the sensing layers have suitable pattern geometry. One example of a touch sensor is a touch screen assembly 10 that includes two patterned conductive coatings or layers 12, 14, as shown in
As shown, the end of each row of the two patterned conductive layers 12, 14 is coupled to one of a set of lead lines 15 that are in turn coupled to a controller 20. The controller 20 may include circuitry for providing excitation currents to the capacitive sensors 12, 14 and for detecting signals generated by the sensors. Further, the controller 20 may include logic for processing the signals and conveying touch information to another part of an electronic device, such as a processor.
The lead lines 15 that connect the transparent conductive layers 12, 14 to the controller 20 may be conductive traces that are screen printed onto the transparent substrate such that they contact the transparent conductive oxide in order to establish an electrical connection between the transparent conductive layers 12,14 and the detection electronics on the controller 20. For example, the traces 15 may be screen printed with an organic paste loaded with silver particles. The traces 18 may have a minimum width of 200 μm with spacing between traces of 200 μm. In this regard, a pitch of the traces, comprising a trace and a space between the next trace, may be 400 μm in width. When considering that numerous pitches are usually provided, the conductive traces 15 occupy a relatively large space on the transparent substrate. This results in border areas 17, 18 surrounding the panel. While the borders 17,18 surrounding the transparent conductive layers function as areas sensitive to touch, the conductive traces 18 are not transparent, and thus in many touch sensor applications (e.g. touch screens) the borders 17, 18 cannot be placed over the display and do not function as part of an active area of the touch sensor. As a result, a non-touch border 23 surrounds the touch sensitive panel, limiting the available portion of the transparent substrate to be used as a touch sensor and requiring that the sensor include a border to accommodate the conductive traces.
The relatively large border 23 may be undesirable for a variety of reasons. As stated above, touch screens may be used in portable or mobile devices such as mobile phones or PDAs. In such applications, it may be desirable to reduce the overall size of the device while maximizing the size of the display and the area used for touch inputs. Accordingly, a large border 23 surrounding the transparent conductive layers 12, 14 detracts from the portion of the transparent substrate that can be used as a touch sensitive input area. Moreover, touch screens used in alternative applications other than mobile devices may also take advantage of a narrow border area in order to meet requirements for display designs, relating either to functionality or the aesthetic quality of the display.
Disclosed herein is a capacitive touch screen panel. The touch screen panel includes a first transparent substrate that includes a first conductive layer disposed adjacent to a surface thereof; a second transparent substrate that includes a second conductive layer disposed adjacent to a surface thereof; a first set of conductive traces disposed on the first transparent substrate and in conductive communication with the first conductive layer; and a second set of conductive traces disposed on the second transparent substrate and in conductive communication with the second conductive layer, wherein at least one of the first set of conductive traces and the second set of conductive traces are deposited by one of electro deposition and vacuum deposition.
A space may separate each of the conductive traces. In addition, each of the conductive traces may have a trace width that is less than 80 μm, and each of the spaces may have a space width that is less than 80 μm.
The capacitive touch screen panel may further comprise a third transparent substrate that includes a third conductive layer disposed adjacent to a surface thereof and a third set of conductive traces disposed on the third transparent substrate and in conductive communication with the third conductive layer, where the third set of conductive traces may be deposited by electro deposition, vacuum deposition, or screen printing. The first transparent substrate, the first conductive layer, and the first set of conductive traces may form a top layer, where a transparent cover layer may be associated with the top layer. The first set of conductive traces may electrically connect with a top surface of the first conductive layer, and the first set of conductive traces may electrically connect with a bottom surface of the first conductive layer.
One of the first and second conductive layers may comprise a pattern of electrodes, and the pattern of electrodes may comprise a pattern of diamond-shaped electrodes. The first and second transparent substrates may comprise a plastic film. The capacitive touch screen panel may be at least partially manufactured using a roll-to-roll process. Once of the first and second conductive layers comprises an indium tin oxide (ITO) layer. The first and second sets of conductive traces may be formed of one or more of aluminum, copper, gold, and silver.
Also disclosed is a method of manufacturing a capacitive touch screen panel. The method includes depositing at least one conductive layer on a first side of a transparent substrate; removing selected portions of the at least one conductive layer; depositing at least one transparent conductive layer on the first side of the transparent substrate; and removing selected portions of the at least one transparent conductive layer, wherein the steps of removing retain an electrical connection between the at least one conductive layer and the at least one transparent conductive layer.
The depositing at least one conductive layer may comprise depositing at least one conductive layer via vacuum deposition, and the depositing at least one transparent conductive layer may comprise depositing at least one transparent conductive layer via vacuum deposition. The removing selective portions of the at least one conductive layer produces a plurality of conductive traces separated by spaces. A trace width of each of the conductive traces may be less than 80 μm, and a space width of each of the spaces may be less than 80 μm.
The method may further comprise patterning the at least one transparent layer, and the transparent conductive layer may comprise an ITO layer. The conductive layer may be formed of one or more of aluminum, copper, gold, and silver.
Also disclosed is a capacitive touch sensor. The capacitive touch sensor includes a transparent substrate having a transparent conductive layer disposed adjacent to a surface thereof and a set of conductive traces disposed on the first transparent substrate, wherein the conductive traces are in conductive communication with the transparent conductive layer, and wherein the conductive traces are deposited using electro deposition or vacuum deposition.
The transparent conductive layer may be patterned, and the conductive traces may electrically connect with a bottom surface of the transparent conductive layer.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but rather, the invention is to cover all modifications, equivalents, and alternatives falling within the scope and spirit of the invention as defined by the claims.
Furthermore, the top substrate 42a may also have a transparent conductive layer of ITO 44a deposited onto it through vacuum deposition, chemical vapor deposition, sputtering, electro deposition, or any other suitable deposition technique. The top ITO layer 44a may also undergo a mask and etch process wherein the top ITO layer 44a is patterned into a desired shape. The shape, for example, may be a diamond-type pattern as shown in
The touch sensor assembly 40 also includes a bottom substrate 42b. The bottom substrate 42b may be any suitable transparent material, including glass or polymer, such as PET. A metal may be deposited onto the bottom substrate 42b, for example through vacuum deposition, sputtering, chemical vapor deposition, electro deposition, or another suitable deposition technique. The metal, once deposited, may further be patterned into a desired shape using a mask and etch process to from conductive traces 50b. The conductive traces 50b deposited onto the substrate may be, but are not limited to, aluminum, copper, gold, silver, or a combination thereof. In addition, a passivation layer may also be deposited (not shown).
Furthermore, the bottom substrate 42b may also have a transparent conductive layer of ITO 44b deposited onto it through vacuum deposition, chemical vapor deposition, sputtering, electro deposition, or another suitable deposition technique. The bottom ITO layer 44b may also undergo a mask and etch process wherein the bottom ITO layer 44b is patterned into a desired shape. The shape may be, for example, a diamond-type pattern as shown in
The top substrate 42a, top ITO layer 44a, and conductive traces 50a may form a top layer 52a. Similarly, the bottom substrate 42b, bottom ITO layer 44b, and conductive traces 50b may form a bottom layer 52b. The top layer 52a and bottom layer 52b may be adhered together by a layer of optically clear adhesive (OCA) 46b. The OCA layer 46b may be a pressure sensitive adhesive. By way of example, the OCA layer 46b may be a pressure sensitive OCA sold by 3M Electronics.
In addition, the top layer 52a may have a cover layer 48 adhered to it such that the top ITO layer 44a has an OCA layer 46a placed adjacent to it. A cover layer 48 may be applied to the OCA 46a such that the cover layer 48 is adhered to the top layer 52a. The cover layer 48 may include any suitable transparent medium. By way of example, the cover layer 48 may be glass or polymer, such as PET.
The top ITO layer 44a and the conductive traces 50a may be deposited onto the top substrate 42a in such a way that the conductive top ITO layer 44a is in conductive contact with the conductive traces 50a. In this regard, electric signals supplied to or received from the top ITO layer 44a may be transmitted via the conductive traces 50a to or from control logic 36 (as shown in
Also, the bottom ITO layer 44b and the conductive traces 50b may be deposited onto the bottom substrate 42b in such a way that the conductive bottom ITO layer 44b is in conductive contact with the conductive traces 50b. In this regard, electric signals supplied to or received from the bottom ITO layer 44b may be transmitted via the conductive traces 50b to or from control logic 36 (as shown in
In another embodiment, shown in
In so much as the conductive traces 50a and 50b may be deposited and patterned according to deposition, mask, etch, and strip techniques, the shape of the conductive traces 50a and 50b may be closely controlled. In this regard, each of the conductive traces may have a trace width that is less than 200 μm. Further still, each of the conductive traces may have a trace width that is less than 100 μm, and in one embodiment, less than 80 μm. As such, the conductive traces 50a and 50b may be arranged such that the traces may be formed in an area smaller than the area required to accommodate the same number of traces applied via a screen printing process. This allows for the conductive connection between the top and bottom ITO layers 44a and 44b to occupy a relatively small area. As the conductive connections have traditionally occupied significant space, the borders of touch sensitive panels have been relatively large. An embodiment of the present invention may have trace widths that are less than 80 μm so that the traces 50a, 50b of the present embodiment may be contained in a much smaller envelope. This may reduce the requisite border size of the touch sensitive panel.
In another embodiment shown in
In one embodiment, a transparent conductive layer 44c (e.g., an ITO layer) may also be deposited onto the third substrate 42c using any appropriate process. The transparent conductive layer may optionally undergo a mask and etch process to pattern the transparent conductive layer 44c into any desired shape such as the diamond-type pattern discussed above and shown in
Additionally, ITO may be deposited (603a, 603b) onto the substrate to form a layer of ITO. The layer of ITO may be patterned (604a, 604b) into a desired shape. This patterning (604a, 604b) may involve covering the ITO layer deposited (603a, 603b) in a photoresist material. The photoresist material may be in the form of a film applied to the deposited ITO layer. The photoresist material may then be developed according to a pattern. After developing the photo resist, an etch and strip process may be employed to remove ITO from areas of the substrate resulting in a patterned ITO layer deposited onto the substrate. The pattern may vary to produce different shapes of ITO on the substrate. For example, one pattern may be used for the top layer 52a and a different pattern be used for the bottom layer 52b to produce differently shaped ITO patterns on the bottom layer. The patterned ITO layers may be aligned and shaped such that the ITO layer is in conductive contact with the copper that has been patterned (602a, 602b).
It is to be understood that the process described herein may be used to produce both the top and bottom layers of the transparent assembly. The top and bottom layers may differ in that different patterns are used to pattern both the copper and the ITO. However, the top and bottom layer may be produced according to similar processes. This does not mean that the top and bottom layers are identical. In addition to different patterns, it is contemplated that the top and bottom layers may have different materials. For instance, the top layer substrate may be a polymer, while the bottom layer substrate may be glass. Additionally, similar materials may also be used.
An OCA may be laminated (605) to a top layer. The OCA may be an appropriate optically clear adhesive and in one embodiment is a pressure sensitive optically clear adhesive. A bottom layer may be laminated (606) to the top layer such that the OCA laminated to the top layer (605) is disposed between the top and bottom layer.
A cover layer may be laminated (610) with an OCA to prepare the cover layer for lamination. For instance, the cover layer may be laminated (607) to the top layer such that the OCA applied to the cover (610) is disposed between the top layer and the cover.
In the method 600, multiple assemblies may be produced such that the substrate may contain multiple individual assemblies on a single quantity of material. The panels produced, which may include a bottom layer laminated to a top layer that is in turn laminated to a cover, may be separated (608) from the remainder of the substrate such that the individual panels may be cut to an approximate final dimension. The separated assemblies may undergo a pressurization treatment (609). The pressurization treatment (609) may include, in one embodiment, placing the assemblies in an autoclave and subjecting the assemblies to a pressure greater than atmospheric pressure. The pressurization process may serve to activate the pressure sensitive adhesive. Moreover, this pressurization process may serve to remove any air bubbles that may develop during the lamination processes in previous steps. Such air bubbles are undesirable because they may cause visual blemishes in the resulting device.
Finally, the assemblies may be finished (611) and the assemblies may undergo inspection. The inspection may include ensuring that the assemblies are the appropriate size, that the assemblies are functional, that the proper conductivity is established, or that the assemblies are free of visual defects such as blemishes or air bubbles. In addition, the assemblies may be cut to final dimensions to ensure the finished assembly is within certain tolerances.
Additionally, while the method described and depicted in
The method 600 of producing touch screen panels may be accomplished using various manufacturing techniques. In one embodiment, the method 600 is accomplished using a roll-to-roll technique. In this manner, the substrate upon which the processes are performed may be initially disposed on a continuous or semi continuous roll of material. The substrate may then be fed through machinery to accomplish the various processes of the method 600 and then spooled onto another roll once the process or processes are accomplished. This technique of roll-to-roll processing may be used in any one or more of the processes of method 600 without limitation. It is understood that a flexible substrate may be employed to effectuate the roll-to-roll processing. In addition, the method 600 may be accomplished using sheet processing such that multiple assemblies are produced from sheets of material. Further still, a combination of sheet and roll-to-roll processing may be used to accomplish the steps in method 600.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character. For example, certain embodiments described hereinabove may be combinable with other described embodiments and/or arranged in other ways (e.g., process elements may be performed in other sequences). Accordingly, it should be understood that only exemplary embodiments and variants thereof have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.
This application claims priority under 35 U.S.C. 119 to U.S. Provisional Application No. 61/223,259, entitled: “NARROW BORDER FOR CAPACITIVE TOUCH PANELS,” filed on Jul. 6, 2009, the contents of which are incorporated herein as if set forth in full.
Number | Date | Country | |
---|---|---|---|
61223259 | Jul 2009 | US |