PATENT DOCUMENT

Publication Number: US-9292141-B2
Application Number: US-201314067810-A
Country: US
Kind Code: B2

Title: Double sided touch sensor on transparent substrate

Abstract:
Compact touch sensors for touch sensitive devices and processes for forming the touch sensors are disclosed. The touch sensor structure can include a substrate, one or more underlying layers disposed on the substrate, one or more blocking layers disposed on the substrate or on one or more underlying layers, and one or more patterned layers disposed on the underlying layers or blocking layers. The one or more blocking layers can be configured to block underlying layers from exposure to certain wavelengths of light or from penetration of a laser beam that can cause damage. Additionally, the one or more underlying layers can be multi-functional, including the ability to block one or more light sources.

Claims:
What is claimed is: 
     
       1. A touch sensor panel comprising:
 a first substrate; 
 a visible area that is transparent to allow light to transmit from a display through the visible area; 
 a plurality of first lines of a first conductive material located in the visible area of the touch sensor and disposed on the first substrate; 
 a border area located on at least one side of the visible area; 
 a plurality of routing traces of a second conductive material located in the border area of the touch sensor panel and disposed on the first substrate and coupled to the plurality of first lines; and 
 one or more blocking layers disposed between the first substrate and the plurality of first lines and located in the visible area and the border area of the touch sensor panel, wherein the one or more blocking layers are configured to block a light source. 
 
     
     
       2. The touch sensor panel of  claim 1 , further comprising:
 a plurality of second lines of the first conductive material; and 
 one or more second blocking layers disposed between the first substrate or a second substrate and the plurality of second lines, wherein the one or more second blocking layers are configured to block another light source. 
 
     
     
       3. The touch sensor panel of  claim 2 , wherein the plurality of second lines is formed on the second substrate, the touch sensor panel further comprising:
 an adhesive layer configured for adhering the second substrate to the first substrate. 
 
     
     
       4. The touch sensor panel of  claim 1 , wherein the one or more blocking layers are configured to block ultraviolet light. 
     
     
       5. The touch sensor panel of  claim 1 , wherein the one or more blocking layers are transparent to visible light. 
     
     
       6. The touch sensor panel of  claim 1 , wherein the one or more blocking layers are configured to have an ablation fluence value greater than the fluence value of the light source. 
     
     
       7. The touch sensor panel of  claim 1 , further comprising:
 one or more underlying layers disposed between the first substrate and the plurality of first lines, wherein the one or more underlying layers are multi-functional and configured to block the light source. 
 
     
     
       8. The touch sensor panel of  claim 1 , wherein the first substrate is configured to block the light source. 
     
     
       9. The touch sensor panel of  claim 1 , wherein at least one of the one or more blocking layers comprises a first section and a second section, the first section located in the visible area of the touch sensor panel and the second section located in the border area of the touch sensor panel, wherein the second section is different from the first section. 
     
     
       10. The touch sensor panel of  claim 1 , wherein at least one of the one or more blocking layers comprises multiple sublayers. 
     
     
       11. The touch sensor panel of  claim 1 , wherein at least one of the one or more blocking layers includes one of a grating, nanoparticle material composite, and dye. 
     
     
       12. The touch sensor panel of  claim 1 , wherein at least one of the one or more blocking layers blocks ultraviolet light and at least one of the one or more blocking layers blocks infrared light. 
     
     
       13. A method for forming a touch sensor panel, the method comprising:
 providing a first substrate; 
 forming a plurality of first lines of a first conductive material on the first substrate and locating the plurality of first lines in a visible area of the touch sensor panel, wherein the visible area is transparent to allow light to transmit from a display through the visible area; 
 forming a plurality of routing traces of a second conductive material on the first substrate and locating the plurality of routing traces in a border area of the touch sensor panel; and 
 forming one or more blocking layers disposed between the first substrate and the plurality of first lines and locating the one or more blocking layers in the visible area and the border area of the touch sensor panel, wherein the one or more blocking layers are configured to block a light source. 
 
     
     
       14. The method of  claim 13 , further comprising:
 providing a second substrate; 
 forming a plurality of second lines of the first conductive material on the second substrate; 
 forming one or more second blocking layers disposed between the second substrate and the plurality of second lines, wherein the one or more second blocking layers are configured to block another light source; and 
 adhering the second substrate to the first substrate. 
 
     
     
       15. The method of  claim 13 , further comprising:
 forming one or more underlying layers disposed between the first substrate and the plurality of first lines, wherein the one or more underlying layers are multi-functional and configured to block the light source. 
 
     
     
       16. The method of  claim 13 , wherein the one or more blocking layers are configured to block at least one of an ultraviolet light source or an infrared light source. 
     
     
       17. The method of  claim 13 , further comprising:
 depositing a third material on the first substrate; 
 patterning the third material with a pattern; and 
 exposing the touch sensor panel with the light source to transfer the pattern from the third material to the first conductive material. 
 
     
     
       18. The touch sensor panel of  claim 6 , wherein the one or more blocking layers have a fluence value between 60-100 mJ/cm 2 . 
     
     
       19. The touch sensor panel of  claim 10 , wherein the multiple sublayers includes TiO 2  and MgF 2 . 
     
     
       20. The touch sensor panel of  claim 1 , wherein at least one of the one or more blocks layers contacts the first conductive material.

Description:
FIELD 
     This relates generally to touch sensor devices, and in particular, to a process for fabricating touch sensor panels for touch sensitive devices. 
     BACKGROUND 
     Touch sensitive devices have become popular as input devices to computing systems due to their ease and versatility of operation as well as their declining price. A touch sensitive device can include a touch sensor panel, which can be a clear panel with a touch sensitive surface, and a display device, such as a liquid crystal display (LCD), that can be positioned partially or fully behind the panel or integrated with the panel so that the touch sensitive surface can cover at least a portion of the viewable area of the display device. The touch sensitive device can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, the touch sensitive device can recognize a touch event and the position of the touch event on the touch sensor panel, and a computing system can interpret the touch event in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch event. 
     One type of touch sensor panel that can be used is a capacitive touch sensor panel. Typical capacitive touch sensor panels can include a grid formed by rows of drive lines intersecting columns of sense lines. The drive lines can be driven by stimulation signals that cause the capacitively coupled sense lines to generate output touch signals representative of touch events detected on the surface of the panel. The drive lines and sense lines can be fabricated on the touch sensor panel using various processes, such as lithography, printing, or laser ablation. Fabricating the touch sensor panel using lithography can be useful for patterning multiple features at once, reducing fabrication time. However, exposure from a light source during the lithography process can penetrate to underlying layers, either on the same side or on the opposite side of the substrate, and alter the properties of those underlying layers. Fabricating the touch sensor panel using laser ablation can be useful for achieving finer patterns for the drive and sense lines. However, the laser ablation process can damage the underlying layers or substrate when the material to be patterned, such as indium tin oxide (ITO) for the drive and sense lines, has a high ablation fluence value. 
     SUMMARY 
     Processes for fabricating compact touch sensors for touch sensitive devices are disclosed. A process can include providing a touch sensor structure having a substrate, one or more underlying layers optionally disposed on the substrate, one or more blocking layers disposed on the substrate or on one or more underlying layers, and one or more patterned layers disposed on the underlying layers or blocking layers. The one or more blocking layers can be formed to block underlying layers from exposure to certain wavelengths of light or from penetration of a laser beam that can cause damage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary touch sensor that can be used to detect touch events on a touch sensitive device 
         FIG. 2  illustrates a cross-sectional view of an exemplary DITO touch sensor structure stackup. 
         FIG. 3  illustrates an exemplary process for manufacturing a touch sensor similar or identical to touch sensor of  FIG. 2 . 
         FIG. 4  illustrates an exemplary cross-sectional view of an exemplary DITO touch sensor structure stackup with blocking layers. 
         FIG. 5A  illustrates a plot of transmittance in the UV spectrum for exemplary ultra-high, high, good, and standard UV blocking layers. 
         FIG. 5B  illustrates an exemplary stackup for a blocking layer designed to block UV light. 
         FIG. 6  illustrates a cross-sectional view of an exemplary SITO touch sensor structure stackup. 
         FIG. 7  illustrates a cross-sectional view of an exemplary SITO touch sensor structure stackup with a blocking layer. 
         FIG. 8A  illustrates a plot of transmittance in the visible and NIR spectrum for exemplary ultra-high, high, good, and standard infrared (IR) blocking layers. 
         FIG. 8B  illustrates an exemplary stackup for an IR blocking layer designed to block IR light, while allowing visible light to pass through. 
         FIG. 9  illustrates an exemplary process for manufacturing a touch sensor using a two substrate lamination process. 
         FIGS. 10A-10D  illustrate cross-sectional views of an exemplary touch sensor structure stackup formed using a two substrate lamination process with blocking layers. 
         FIG. 11  illustrates an exemplary computing system that can include one or more examples of the disclosure. 
         FIGS. 12A-12C  illustrate an exemplary mobile telephone, media player, and personal computer that can include a touch sensor panel and display device according to various examples of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the various examples. 
     This disclosure relates to processes for fabricating compact touch sensors for touch sensitive devices. A process can include providing a touch sensor structure having a substrate, one or more underlying layers optionally disposed on the substrate, one or more blocking layers disposed on the substrate or on one or more underlying layers, and one or more patterned layers disposed on the underlying layers or blocking layers. In some examples, one or more passivation layers can be disposed on the patterned layers. The one or more underlying layers, blocking layers, and patterned layers can be deposited on the same side of the substrate or on different sides of the substrate. The processes can be used in sheet-to-sheet processes for rigid or flexible substrates, roll-to-roll processes for flexible substrates, or processes for curved substrates. 
       FIG. 1  illustrates an exemplary touch sensor  100  that can be used to detect touch events on a touch sensitive device, such as a mobile phone, tablet, touchpad, portable computer, portable media player, or the like. Touch sensor  100  can include an array of touch regions  105  that can be formed at the crossing points between rows of drive lines  101  (D0-D3) and columns of sense lines  103  (S0-S4). Each touch region  105  can have an associated mutual capacitance Csig  111  formed between the crossing drive lines  101  and sense lines  103  when the drive lines are stimulated. The drive lines  101  can be stimulated by stimulation signals  107  provided by drive circuitry (not shown) and can include an alternating current (AC) waveform. The sense lines  103  can transmit touch signals  109  indicative of a touch at the touch sensor  100  to sense circuitry (not shown), which can include a sense amplifier for each sense line, or a fewer number of sense amplifiers that can be multiplexed to connect to a larger number of sense lines. 
     To sense a touch at the touch sensor  100 , drive lines  101  can be stimulated by the stimulation signals  107  to capacitively couple with the crossing sense lines  103 , thereby forming a capacitive path for coupling charge from the drive lines  101  to the sense lines  103 . The crossing sense lines  103  can output touch signals  109 , representing the coupled charge or current. When a user&#39;s finger (or other object) touches or hovers over the touch sensor  100 , the finger can cause the capacitance Csig  111  to reduce by an amount ΔCsig at the touch location. This capacitance change ΔCsig can be caused by charge or current from the stimulated drive line  101  being shunted through the touching finger to ground rather than being coupled to the crossing sense line  103  at the touch location. The touch signals  109  representative of the capacitance change ΔCsig can be transmitted by the sense lines  103  to the sense circuitry for processing. The touch signals  109  can indicate the touch region where the touch occurred and the amount of touch that occurred at that region location. 
     While the example shown in  FIG. 1  includes four drive lines  101  and five sense lines  103 , it should be appreciated that touch sensor  100  can include any number of drive lines  101  and any number of sense lines  103  to form the desired number and pattern of touch regions  105 . Additionally, while the drive lines  101  and sense lines  103  are shown in  FIG. 1  in a crossing configuration, it should be appreciated that other configurations are also possible to form the desired touch region pattern. While  FIG. 1  illustrates mutual capacitance touch sensing, other touch sensing technologies may also be used in conjunction with examples of the disclosure, such as self-capacitance touch sensing, resistive touch sensing, projection scan touch sensing, and the like. Furthermore, while various examples describe a sensed touch, it should be appreciated that the touch sensor  100  can also sense a hovering object and generate hover signals therefrom. 
     Touch sensor panels can be implemented as an array of pixels formed by multiple drive lines (e.g. rows) crossing over multiple sense lines (e.g. columns), where the drive lines and sense lines can be separated by a dielectric material. In some touch sensor panels, the drive and sense lines can be formed on the top and bottom sides of the same transparent substrate. In other touch sensor panels, the drive and sense lines may formed on one side of the transparent substrate. The drive lines and sense lines can be formed from a substantially transparent material, such as Indium Tin Oxide (ITO), although other materials can also be used. The ITO layer(s) can be deposited on one or both sides of the transparent substrate. Touch sensor panels with double or single sided ITO layers are referred to as double-sided ITO (DITO) touch sensor panels and single-sided ITO (SITO) touch sensor panels, respectively, in the disclosure. 
       FIG. 2  illustrates a cross-sectional view of an exemplary DITO touch sensor structure  200  stackup. Touch sensor structure  200  can include a substrate  202  made of any transparent substrate material, such as plastic, glass, quartz, a rigid or flexible glass, or a rigid or flexible composite. Touch sensor structure  200  can further include one or more layers  204  and  214 , such as a hard coating layer or an index matching layer, disposed on the top surface  230  and bottom surface  232  of substrate  202 . Drive lines can be formed by disposing a layer of transparent conductive film  206  on layers  204 , and sense lines can be formed by disposing a layer of transparent conductive film  216  on layers  214 . Transparent conductive films  206  and  216  can be any electrically conductive material, such as ITO, IZO, ITZO, AgNW, AgCl, CNT, Graphene, other metals, other oxides, or the like. Metal layers  208  and  218  can be deposited on the transparent conductive film  206  and  216  for forming routing traces for the drive and sense lines of the touch sensor structure  200 . The metal layers  208  and  218  can be made of copper or any other metal suitable for routing signals on the touch sensor structure  200 . The transparent conductive film  206  and metal layer  208  can be patterned to form the drive lines and routing traces for the drive lines by depositing a mask  210 . Similarly, transparent conductive film  216  and metal layer  218  can be patterned to form the sense lines and routing traces for the sense lines by depositing a mask  220 . Masks  210  and  220  can include any light sensitive material, such as photoresist. Exposure of portions of the masks  210  and  220  to light, such as ultraviolet (UV) light, can alter the chemistry of the mask and change one or more properties, such as solubility, relative to the unexposed portions. Layers  204  and  214 , transparent conductive films  206  and  216 , metal layers  208  and  218 , and masks  210  and  220  can be formed at the same time. Both sides of the touch sensor structure can be exposed to light sources, such as light sources  240  and  242 , for forming patterns for the drive and sense lines and routing traces. Light from the light sources can penetrate from both sides of the substrate and reach the other sides of the substrate, causing backside interference and inadvertently altering the properties of one of the masks  210  or  220  or both. Altering the properties of one or more masks can lead to unwanted changes in the feature sizes of the drive and/or sense lines. In some examples, a laser source, such as one used in laser ablation, can penetrate from both sides of the substrate and reach the other sides of the substrate, causing backside interference or damage to one or more underlying layers, altering the properties of the masks, underlying layers, transparent conductive films, or metal layers. 
     Once the drive and sense lines and routing traces for the drive and sense lines are patterned, masks  210  and  220  can be removed. Metal layers  208  and  218  in the visible area of the touch sensor structure can be removed, and an optional passivation layer can be deposited on top. Passivation layer can be made of any material that can protect and/or planarize the touch sensor structure  200  including any organic material, such as a polymer or an optically clear adhesive. In some examples, masks  210  and  220  can serve as a multi-purpose material and may act not only as a mask during patterning but also as a passivation layer. 
     The touch sensor structure can include one or more blocking layers to one or more sides of the substrate.  FIG. 3  illustrates an exemplary process  300  for manufacturing a touch sensor similar or identical to touch sensor  100 . Process  300  can be described below with reference to  FIG. 4 .  FIG. 4  illustrates an exemplary cross-sectional view of an exemplary DITO touch sensor structure  400  stackup with blocking layers. The exemplary touch sensor structure  400  of  FIG. 4  can be used in process  300 . At block  301 , a substrate can be provided. Substrate  402  can be made of any substrate material, such as plastic, glass, or quartz. At block  303 , one or more blocking layers  450  and  452  can be disposed on the top surface  430  and bottom surface  432 . At block  305 , one or more layers  404  and  414  can be disposed on the blocking layers  450  and  452 . Layers  404  and  414  can include, for example, hard coating layers and index matching layers. At block  307 , transparent conductive films  406  and  416  can be deposited, and at block  309 , metal layers  408  and  418  can be deposited. At block  311 , masks  410  and  420  can be deposited. Light sources  440  and  442  can be directed at the touch sensor structure  400  for exposing portions of the masks  410  and  420  to form a pattern to be transferred to the metal layers  408  and  418  and transparent conductive films  406  and  416 . During exposure of the touch sensor structure to the light sources  440  and  442 , blocking layers  450  and  452  can prevent unwanted backside light interference. At block  313 , the transparent conductive films  406  and  416  can be etched to form the drive and sense lines. At block  315 , masks  410  and  420  can be removed. At block  317 , metal in the visible area can be removed, and at block  319 , an optional passivation or planarization layer can be deposited. While  FIGS. 3-4  illustrate blocking layers  450  and  452  disposed between the substrate  402  and the layers  404  and  414 , blocking layers  450  and  452  can be disposed anywhere between the transparent conductive films  406  and  416  and the substrate  402  such that they block underlying layers. In some examples, the blocking layer  450  can be disposed between layers  404  and transparent conductive film  406 . In some examples, the blocking layer  452  can be disposed between layers  414  and transparent conductive film  416 . In some examples, the blocking layers  450  and/or  452  can be disposed between any of the layers  404  or  414 , such as between a hard coating layer and an index matching layer. While  FIG. 4  illustrates two blocking layers  450  and  452 , examples of the disclosure include, but are not limited to, one or more than two blocking layers. Additionally, examples of the disclosure are not limited to the location of the blocking layers and the number of blocking layers being the same on both sides of the substrates. In some examples, the blocking layers can be utilized in touch sensor panels employing a SITO arrangement. 
     In some examples, one or more layers of  FIG. 4  can be chosen to be multi-functional layers such that at least one of the functions includes blocking backside interference. For example, the index matching layer can be multi-functional including index matching for improved optical uniformity and blocking for preventing certain types of light from penetrating through. In some examples, the substrate can be chosen to have an inherent property of blocking certain wavelengths of light. The substrate can pass through certain wavelengths, such as light in the visible spectrum, while also blocking other wavelengths, such as light in the UV spectrum. By choosing a substrate with an inherent property of blocking certain wavelengths of light, a thinner touch sensor panel can be achieved. In some examples, the one or more blocking layers can cover certain portions of the touch screen. In some examples, the one or more blocking layers can comprise two or more different sections. For example, the border region, where the routing traces are located, can have one type of blocking layer, and the visible area, where the touch sensors are located, can have another type of blocking layer. 
     The blocking layer can comprise a single layer or multiple sublayers that block specific wavelengths or one or more wavelength ranges. Additionally, a blocking layer can be chosen based on the amount of transmittance allowed to pass through. The blocking layer can be categorized based on this transmittance. For example, an ultra-high blocking layer can have a transmittance less than 1%. A high blocking layer can have a transmittance between 1% and 20%. A good blocking layer can have a transmittance between 20% and 40%, and a standard blocking layer can have a transmittance between 40% and 60%. The blocking layer can be deposited using different deposition techniques such as sputtering, evaporation, molecular-beam epitaxy, chemical vapor deposition, and printing. 
       FIG. 5A  illustrates a plot of transmittance in the UV spectrum for exemplary ultra-high, high, good, and standard UV blocking layers. The blocking layer can be chosen to shield or block certain wavelengths of light, such as UV light, while allowing other wavelengths of light, such as visible light, to pass through.  FIG. 5B  illustrates an exemplary stackup for a blocking layer designed to block UV light. The example blocking layer includes 12 sublayers alternating between a high refractive index material, material 1  550 A, and a low refractive index material, material 2  550 B. For example, material 1  550 A can be TiO 2  and material 2  550 B can be MgF 2 . The thickness of each sublayer can be determined based on the type of desired blocking layer (e.g. ultra-high, high, good, or standard). Example thickness values for each sublayer are shown in Table 1 below: 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Refractive 
                 Extinction 
                 Thickness 
               
               
                 Sublayer 
                 Material 
                 index 
                 coefficient 
                 (nm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1 
                 TiO 2   
                 2.54627 
                 0.00253 
                 12.67 
               
               
                 2 
                 MgF 2   
                 1.3899 
                 0 
                 89.96 
               
               
                 3 
                 TiO 2   
                 2.54627 
                 0.00253 
                 46.52 
               
               
                 4 
                 MgF 2   
                 1.3899 
                 0 
                 58.62 
               
               
                 5 
                 TiO 2   
                 2.54627 
                 0.00253 
                 38.35 
               
               
                 6 
                 MgF 2   
                 1.3899 
                 0 
                 79 
               
               
                 7 
                 TiO 2   
                 2.54627 
                 0.00253 
                 41.07 
               
               
                 8 
                 MgF 2   
                 1.3899 
                 0 
                 60.2 
               
               
                 9 
                 TiO 2   
                 2.54627 
                 0.00253 
                 43.16 
               
               
                 10 
                 MgF 2   
                 1.3899 
                 0 
                 73.16 
               
               
                 11 
                 TiO 2   
                 2.54627 
                 0.00253 
                 22.05 
               
               
                 12 
                 MgF 2   
                 1.3899 
                 0 
                 70.26 
               
               
                   
               
            
           
         
       
     
     The exemplary blocking layer in  FIG. 5B  and Table 1 was designed as an ultra-high UV blocking layer for an g, h, i-line standard lithography process. The refractive index and extinction coefficient values are given at 380 nm. While  FIG. 5B  is one example blocking layer, any number of different configurations or materials can be employed. In some examples, the blocking layer can have a gradient refractive index. In some examples, the blocking layer can be a filter, such as a high pass, low pass, broadband, or narrow band filter. In some examples, the blocking layer can be designed to prevent penetration of light at specific wavelengths typical of exposure systems for lithography, such as 365 nm, 405 nm, and 436 nm. In some examples, one or more sublayers can include a diffraction grating or can be made from a material composite comprised of nanoparticles or dye. 
     Some touch sensor panels can be processed using laser ablation instead of or in addition to lithography. The precise control with laser ablation can be used to achieve finer patterning and smaller distances between lines and traces. However, the laser ablation process can damage the underlying layers or substrate when the underlying layers and/or substrate absorb the energy from the laser. Laser ablation removes a material by irradiating the material with high power laser pulses. The material can absorb the energy from the laser, heat up, and then be removed by vaporization. If the energy of the absorbed laser pulse is sufficient to break the chemical bonds of the material, the material can be ablated. The depth that the laser can penetrate and remove material can depend on several factors, such as the laser beam energy density, or laser fluence value, and absorption coefficient of the material at wavelengths of the laser beam. A material can have what is known as an ablation fluence value, which is an energy value (energy per unit area) or a threshold level needed by the laser beam in order for ablation of the material can occur. As the material is being ablated, the laser can penetrate to underlying layers. The underlying layers can be etched or damaged if the underlying layers are capable of absorbing energy at the same wavelength as the laser emission wavelength, and also if the laser beam has a fluence value that is greater than or equal to the ablation fluence value of the underlying layers. 
       FIG. 6  illustrates a cross-sectional view of an exemplary SITO touch sensor structure  600  stackup. Touch sensor structure  600  can include a substrate  602 . Touch sensor structure  600  can further include one or more layers, such as a hard coating layer  604  and an index matching layer  605 , disposed on the substrate  602 . Drive lines or sense lines can be formed by disposing a layer of transparent conductive film  606  on the hard coating and index matching layers  604  and  605 . A mask  610  can be deposited on the transparent conductive film  606  for patterning. A laser or light source  640  can be directed at the touch sensor structure  600 . Once the pattern of the mask  610  is transferred to the transparent conductive film  606  and transparent conductive film is etched, the laser can be incident on one or more of the hard coating layer  604 , index matching layer  605 , substrate  602 , or any underlying layers in the touch sensor structure  600 . If one or more underlying layers can absorb energy at the laser emission wavelength and the laser fluence value is greater than or equal to the ablation fluence value of the underlying layers, the underlying layers can be removed and/or damaged. Degradation in their material properties can result from film distortion, wrinkling, or change in electrical or optical properties, and as a result, can lead to degradation in the performance of the touch sensor panel. The damage from the laser beam can occur during the patterning of any of the layers, such as the drives line, the sense lines, or routing traces. 
     One or more blocking layers can be added to one or more sides of the touch sensor structure.  FIG. 7  illustrates a cross-sectional view of an exemplary SITO touch sensor structure  700  stackup with a blocking layer. Touch sensor structure  700  can include substrate  702 , hard coating layer  704 , index matching layer  705 , blocking layer  750 , transparent conductive film  706 , and mask  710 . When a light source, such as a laser beam  740 , is directed at the touch sensor structure  700  for etching portions of a layer, such as the transparent conductive film  706 , a blocking layer  750  can prevent penetration of the laser beam  740  to layers underneath the blocking layer  750 , such as the hard coating layer  704 , index matching layer  705 , and substrate  702 . While  FIG. 7  illustrates blocking layer  750  disposed between index matching layer  705  and transparent conductive film  706 , the blocking layer  750  can be disposed anywhere beneath the layer being patterned by the laser ablation process. In some examples, the blocking layer  750  can be disposed between the substrate  702  and the hard coating layer  704 . In some examples, the blocking layer  750  can be disposed between the hard coating layer  704  and the index matching layer  705 . In some examples, the touch sensor structure  700  can comprise additional layers and the blocking layer may be disposed anywhere within the structure, but below the layer to be patterned, such as the transparent conductive film  706 . In some examples, the touch sensor structure can be a DITO stackup, and one or more blocking layers can be disposed on either side of the substrate or both sides. 
     The blocking layer  750  can comprise one or more sublayers that have strong absorbing or reflecting properties at the laser emission wavelengths. For example, the laser source can have an emission wavelength in the UV spectrum from 150 nm to 400 nm. The blocking layer  750  can include one or more sublayers with strong absorbing or reflecting properties in the wavelength range of 150 nm to 400 nm. Alternatively, a near-infrared (NIR) laser source can be used with an emission wavelength from 800 nm to 1100 nm, and a blocking layer can absorb and/or reflect the laser energy in that wavelength range. 
       FIG. 8A  illustrates a plot of transmittance in the visible and NIR spectrum for exemplary ultra-high, high, good, and standard infrared (IR) blocking layers. Any one of the blocking layers can prevent at least a partial amount of energy from penetrating to one or more layers underneath the blocking layers from, for example, an incident NIR laser source. Additionally, the blocking layer can be transparent to other wavelengths of light, such as visible light. The IR blocking layer can then prevent damage or degradation of touch sensor panel due to manufacturing without affecting the visibility of a display located under the touch sensor panel.  FIG. 8B  illustrates an exemplary stackup for an IR blocking layer designed to block IR light, while allowing visible light to pass through. The IR blocking layer stackup shown in the figure can include 12 sublayers alternating between a low refractive index material, material 1  850 A, and a high refractive index material, material 2  805 B. For example, material 1  850 A can be MgF 2  and material 2  550 B can be TiO 2 . The thickness of each sublayer can be determined based on the type of desired blocking layer (e.g. ultra-high, high, good, or standard). Example thickness values for each sublayer are shown in Table 2 below: 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 Refractive 
                 Extinction 
                 Thickness 
               
               
                 Sublayer 
                 Material 
                 index 
                 coefficient 
                 (nm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1 
                 MgF 2   
                 1.3803 
                 0 
                 91.58 
               
               
                 2 
                 TiO 2   
                 2.25 
                 0 
                 105.65 
               
               
                 3 
                 MgF 2   
                 1.3803 
                 0 
                 192.19 
               
               
                 4 
                 TiO 2   
                 2.25 
                 0 
                 115.87 
               
               
                 5 
                 MgF 2   
                 1.3803 
                 0 
                 194.09 
               
               
                 6 
                 TiO 2   
                 2.25 
                 0 
                 113.01 
               
               
                 7 
                 MgF 2   
                 1.3803 
                 0 
                 187.96 
               
               
                 8 
                 TiO 2   
                 2.25 
                 0 
                 110.31 
               
               
                 9 
                 MgF 2   
                 1.3803 
                 0 
                 188.66 
               
               
                 10 
                 TiO 2   
                 2.25 
                 0 
                 111.51 
               
               
                 11 
                 MgF 2   
                 1.3803 
                 0 
                 191.1 
               
               
                 12 
                 TiO 2   
                 2.25 
                 0 
                 115.15 
               
               
                   
               
            
           
         
       
     
     The exemplary blocking layer in  FIG. 8B  and Table 2 was designed as an ultra-high IR blocking layer for a standard YAG laser to be used for a laser ablation process. The refractive index and extinction coefficient values are given at 1064 nm. Additionally, the blocking layer can include one or more of a high pass filter, low pass filter, narrowband filter, broadband filter, diffraction grating, material with gradient refractive index, or a material composite comprising nanoparticles. 
     In addition or alternatively to one or more blocking layers chosen based on absorbing or reflecting wavelengths of the blocking layer, the blocking layer can be based on the ablation fluence value. The blocking layer can have an ablation fluence value that is greater than the laser fluence value, while the layer to be patterned can have an ablation fluence value that is equal or less than the laser fluence value. Thus, when a laser has a laser fluence value that is greater than or equal to the ablation fluence value of the layer to be patterned, such as the transparent conductive film  706 , and less than the ablation fluence value of the blocking layer  750 , portions of the transparent conductive film  706  can be removed without removing the blocking layer and without damaging underlying layers, such as the index matching layer, hard coating layer, and substrate. For example, transparent conductive film  706  can have a fluence value that is greater than 2 mJ/cm 2  and the blocking layer can have an ablation fluence value of approximately 60-100 mJ/cm 2 . Thus, a laser with a laser fluence value between 2-60 mJ/cm 2  can be applied to the touch sensor structure  700  to selectively pattern the drive or sense lines from the transparent conductive film  706  without damage or degradation to the properties of the touch sensor structure. 
     In some examples, one or more layers of  FIG. 7  can be chosen to be multi-functional layers such that at least one of the functions includes blocking penetration of the laser beam. For example, the index matching layer can be multi-functional including index matching for improved optical uniformity and blocking of the laser beam. In some examples, the substrate can be chosen to have an inherent property of absorbing or reflecting at wavelengths outside of the visible spectrum and/or can have an ablation fluence value greater than the laser fluence value. By choosing a substrate or one or more layers with an inherent property of blocking the laser beam from penetrating, a separate layer for blocking can be avoided and a thinner touch sensor panel can be achieved. In some examples, the one or more blocking layers can cover certain portions of the touch screen. In some examples, the one or more blocking layers can comprise two or more different materials. For example, the border region where the routing traces are located can have one type of blocking layer, and the visible area where the touch sensors are located can have another type of blocking layer. In some examples, the touch sensor structure can include one or more different types of blocking layers, such as both a UV blocking layer and an IR blocking layer. 
     In addition to the SITO and DITO structures, one or more blocking layers can be included when the touch sensor structure is formed using other techniques, such as a two substrate lamination process.  FIG. 9  illustrates an exemplary process  900  for manufacturing a touch sensor using a two substrate lamination process. Process  900  can be described below with reference to  FIGS. 10A-10C .  FIGS. 10A-10C  illustrate cross-sectional views of an exemplary touch sensor structure  1000  stackup formed using a two substrate lamination process with blocking layers. The top portion  1030  and bottom portion  1032  can be formed on separate substrates  1001  and  1002 , where the bottom portion  1032  can be formed following the top portion  1030 . At step  901 , two substrates can be provided. At step  903 , the substrates can be bonded together using an adhesive  1070 . At step  905 , one or more underlying layers can be deposited, such as hard coating layer  1004  and index matching layer  1005 . At step  907 , blocking layer  1050  can be deposited, and at step  909 , transparent conductive film  1006  can be disposed on the blocking layer  1050 . At step  911 , metal layer  1008  can be deposited. At step  913 , mask  1010  can be deposited and top portion  1030  can be exposed to light source  1004 . At step  915 , metal layer  1008  and transparent conductive film  1006  can be ablated or etched using a source, such as a laser, to form drive lines  1060  and routing. At step  917 , mask  1010  can be removed, and metal layer  1008  can be removed in the visible area of the touch sensor structure  1000 , at step  919 . At step  921 , an optional passivation layer  1012  can be deposited. At step  932 , the structure can be flipped, and the process can continue from steps  925 - 939  to form the underlying layers  1014 - 1015 , blocking layer  1052 , transparent conductive film  1016 , metal layer  1018 , and mask  1020  can be formed on the bottom portion  1032 , as shown in  FIG. 10B . At step  941 , an optional passivation layer  1022  can be deposited, as shown in  FIG. 10C . 
     In some examples, top portion  1030  and bottom portion  1032  can be formed simultaneously or side-by-side, as exemplified in  FIG. 10D . Blocking layers  1050  and  1052  can be used to block exposure or penetration of a light source, similar to the various examples of the disclosure discussed above. In some examples, the touch sensor structure  1000  can include both UV and IR blocking layers for processes that use both lithography and laser ablation, for example. Bonding of the top and bottom portions  1030  and  1032  together can be performed at any step of the process, such as the last step after the drive and sense lines have been formed, and is not limited to occurring before the portions are formed. Additionally, examples of the disclosure are not limited to the steps or the order of the steps shown in  FIG. 9 . In some examples, a blocking layer can be disposed between the substrates  1001  and  1002 . In some examples, the adhesive  1070  can be multi-functional to include the capability of bonding the substrate while also serving as a blocking layer. 
       FIG. 11  illustrates exemplary computing system  1100  that can utilize touch controller  1106  according to various examples of the disclosure. Touch controller  1106  can be a single application specific integrated circuit (ASIC) that can include one or more processor subsystems  1102 , which can include, for example, one or more main processors, such as ARM968 processors or other processors with similar functionality and capabilities. However, in other examples, some of the processor functionality can be implemented instead by dedicated logic, such as a state machine. Processor subsystems  1102  can also include, for example, peripherals such as random access memory (RAM)  1112  or other types of memory or storage, watchdog timers (not shown), and the like. Touch controller  1106  can also include, for example, receive section  1107  for receiving signals, such as touch sense signals  1103 , from the sense lines of touch sensor panel  1124 , and other signals from other sensors such as sensor  1111 , etc. Touch controller  1106  can also include, for example, a demodulation section such as multistage vector demod engine  1109 , panel scan logic  1110 , and a drive system including, for example, transmit section  1114 . Panel scan logic  1110  can access RAM  1112 , autonomously read data from the sense channels, and provide control for the sense channels. In addition, panel scan logic  1110  can control transmit section  1114  to generate stimulation signals  1116  at various frequencies and phases that can be selectively applied to the drive lines of the touch sensor panel  1124 . 
     Charge pump  1115  can be used to generate the supply voltage for the transmit section. Stimulation signals  1116  (Vstim) can have amplitudes higher than the maximum voltage the ASIC process can tolerate by cascading transistors. Therefore, using charge pump  1115 , the stimulus voltage can be higher (e.g. 6V) than the voltage level a single transistor can handle (e.g. 3.6 V). Although  FIG. 11  shows charge pump  1115  separate from transmit section  1114 , the charge pump can be part of the transmit section. 
     Touch sensor panel  1124  can include a capacitive sensing medium having a plurality of drive lines and a plurality of sense lines. The drive and sense lines can be formed from a transparent conductive medium such as Indium Tin Oxide (ITO) or Antimony Tin Oxide (ATO), although other transparent and non-transparent materials such as copper can also be used. In some examples, the drive and sense lines can be perpendicular to each other, although in other examples other non-Cartesian orientations are possible. For example, in a polar coordinate system, the sensing lines can be concentric circles and the driving lines can be radially extending lines (or vice versa). It should be understood, therefore, that the terms “drive lines” and “sense lines” as used herein are intended to encompass not only orthogonal grids, but the intersecting traces or other geometric configurations having first and second dimensions (e.g. the concentric and radial lines of a polar-coordinate arrangement). The drive and sense lines can be formed on, for example, a single side of a substantially transparent substrate. 
     At the “intersections” of the traces, where the drive and sense lines can pass adjacent to and above and below (cross) each other (but without making direct electrical contact with each other), the drive and sense lines can essentially form two electrodes (although more than two traces could intersect as well). Each intersection of drive and sense lines can represent a capacitive sensing node and can be viewed as pixel or node  1126 , which can be particularly useful when touch sensor panel  1124  is viewed as capturing an “image” of touch. (In other words, after touch controller  106  has determined whether a touch event has been detected at each touch sensor in the touch sensor panel, the pattern of touch sensors in the multi-touch panel at which a touch event occurred can be viewed as an “image” of touch (e.g. a pattern of fingers touching the panel.) The capacitance between drive and sense electrodes can appear as a stray capacitance when the given row is held at direct current (DC) voltage levels and as a mutual signal capacitance Csig when the given row is stimulated with an alternating current (AC) signal. The presence of a finger or other object near or on the touch sensor panel can be detected by measuring changes to a signal charge Qsig present at the pixels being touched, which is a function of Csig. 
     Computing system  1100  can also include host processor  1128  for receiving outputs from processor subsystems  1102  and performing actions based on the outputs that can include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device, answering a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like. Host processor  1128  can perform additional functions that may not be related to panel processing, and can be coupled to program storage  1132  and display device  1130  such as an LCD display for providing a UI to a user of the device. In some examples, host processor  1128  can be a separate component for touch controller  1106 , as shown. In other examples, host processor  1128  can be included as part of touch controller  1106 . In other examples, the functions of host processor  1128  can be performed by processor subsystem  1102  and/or distributed among other components of touch controller  1106 . Display device  1130  together with touch sensor panel  1124 , when located partially or entirely under the touch sensor panel, can form touch screen  1118 . 
     Note that one or more of the functions described above can be performed, for example, by firmware stored in memory (e.g. one of the peripherals) and executed by processor subsystem  1102 , or stored in program storage  1132  and executed by host processor  1128 . The firmware can also be stored and/or transported within any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “non-transitory computer-readable storage medium” can be any medium (excluding a signal) that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The non-transitory computer readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such as a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, or infrared wired or wireless propagation medium. 
       FIG. 12A  illustrates exemplary mobile telephone  1236  that can include touch sensor panel  1224  and display device  1230 .  FIG. 12B  illustrates exemplary media player  1240  that can include touch sensor panel  1224  and display device  1230 .  FIG. 12C  illustrates an exemplary personal computer  1244  that can include touch sensor panel (trackpad)  1224  and display  1230 . The touch sensor panels  1224  can include one or more blocking layers according to examples of the disclosure. In some examples, the display  1230  can be part of a touch screen. 
     In some examples, a touch sensor panel is disclosed. The touch sensor panel may comprise: a substrate; a plurality of first lines of a first conductive material; and one or more blocking layers disposed between the substrate and the plurality of first lines, wherein the one or more blocking layers are configured to block a light source. Additionally or alternatively to one or more examples disclosed above, in other examples the touch sensor panel, further comprises: a plurality of second lines of the first conductive material; and one or more second blocking layers disposed between the substrate and the plurality of second lines, wherein the one or more second blocking layers are configured to block a light source. Additionally or alternatively to one or more examples disclosed above, in other examples the touch sensor panel, further comprises: a second substrate, wherein the plurality of second lines is formed on the second substrate; and an adhesive layer configured for adhering the second substrate to the first substrate. Additionally or alternatively to one or more examples disclosed above, in other examples, the blocking layer is configured to block ultraviolet light. Additionally or alternatively to one or more examples disclosed above, in other examples the blocking layer is transparent to visible light. Additionally or alternatively to one or more examples disclosed above, in other examples the blocking layer is configured to block infrared light. Additionally or alternatively to one or more examples disclosed above, in other examples the blocking layer is configured to have an ablation fluence value greater than the fluence value of the light source. Additionally or alternatively to one or more examples disclosed above, in other examples the touch sensor panel further comprises: a second substrate, wherein the plurality of first lines are disposed on the substrate and the plurality of second lines are disposed on the second substrate. Additionally or alternatively to one or more examples disclosed above, in other examples the touch sensor panel further comprises: an adhesive configured for bonding the substrate to the second substrate. Additionally or alternatively to one or more examples disclosed above, in other examples the touch sensor panel further comprises: one or more underlying layers disposed between the substrate and at least one of the plurality of first lines and plurality of second lines, wherein the one or more underlying layers are multi-functional and configured to block a light source. Additionally or alternatively to one or more examples disclosed above, in other examples, the substrate is configured to block a light source. Additionally or alternatively to one or more examples disclosed above, in other examples a blocking layer in the visible area of the touch sensor panel is different from a blocking layer in the border area. Additionally or alternatively to one or more examples disclosed above, in other examples at least one of the blocking layers comprises multiple sublayers. Additionally or alternatively to one or more examples disclosed above, in other examples at least one of the blocking layers is a grating, a nanoparticle material composite, or a dye. Additionally or alternatively to one or more examples disclosed above, in other examples at least one of the blocking layers blocks ultraviolet light and at least one of the blocking layers blocks infrared light. 
     In some examples, a method for forming a touch sensor panel is disclosed. The method may comprise: providing a substrate; forming a plurality of first lines of a first conductive material; and forming one or more blocking layers disposed between the substrate and the plurality of first lines, wherein the one or more blocking layers are configured to block a light source. Additionally or alternatively to one or more examples disclosed above, in other examples the method further comprises: forming a plurality of second lines of the first conductive material; and forming one or more second blocking layers disposed between the substrate and the plurality of second lines, wherein the one or more second blocking layers are configured to block a light source. Additionally or alternatively to one or more examples disclosed above, in other examples the method further comprises: providing a second substrate; forming a plurality of second lines of the first conductive material on the second substrate; forming one or more second blocking layers disposed between the second substrate and the plurality of second lines, wherein the one or more second blocking layers are configured to block a light source; and adhering the second substrate to the first substrate. Additionally or alternatively to one or more examples disclosed above, in other examples the method further comprises: forming one or more underlying layers disposed between the substrate and at least one of the plurality of first lines and plurality of second lines, wherein the one or more underlying layers are multi-functional and configured to block a light source. Additionally or alternatively to one or more examples disclosed above, in other examples the one or more blocking layers are configured to block at least one of an ultraviolet light source or an infrared light source. 
     While various examples have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Although examples have been fully described with reference to the accompanying drawings, the various diagrams may depict an example architecture or other configuration for this disclosure, which is done to aid in the understanding of the features and functionality that can be included in the disclosure. The disclosure is not restricted to the illustrated exemplary architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, although the disclosure is described above in terms of various examples and implementations, it should be understood that the various features and functionality described in one or more of the examples are not limited in their applicability to the particular example with which they are described. They instead can be applied alone or in some combination, to one or more of the other examples of the disclosure, whether or not such examples are described, and whether or not such features are presented as being part of a described example. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described examples.

Metadata:
Filing Date: 20131030
Publication Date: 20160322
Grant Date: 20160322
Priority Date: 20131030
Inventors: ZHONG JOHN Z.
KANG SUNGGU
PEDDER JAMES EDWARD ALEXANDER
TUNG CHUN-HAO
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/044", "inventive": true, "first": true, "tree": "[]"}, {"code": "B32B2457/208", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B2457/208", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2457/208", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 52994830