The force sensing ability of QTC can be used in many applications, but it has created a large amount of interest amongst mobile device developers, who are excited by the potential of adding another dimension to Human Machine Interaction – pressure. Because the harder QTC is pressed, the more current flows through it, the result is a smooth, analogue third dimension of input into the digital world of the mobile phone.
Thus, for example, pressing harder could make a menu scroll faster, a line wider or an avatar jump higher in computer games. Unfortunately, as QTC is made from metal particles in a polymer, it is opaque and this has presented a problem in making pressure sensitive screens for mobile phones. Peratech's initial solution to this problem was screen printing a series of QTC dots around the perimeter of the screen.
These dots detect the applied force as they are compressed against the screen's mounting – rather like a gasket. Having determined there was a market amongst mobile device developers for force sensing devices, Peratech continued to research into ways to create what was required – a clear version of QTC. And this has been achieved in the form of QTC Clear. This can be screen printed to form a thin layer that has minimal impact on transparency, being similar to that of a layer of indium tin oxide (ITO).
Not only does QTC Clear provide pressure sensitive 3d input with a proportional response, but it also breaks through the barrier that has until now kept touch screens restricted to small screen applications. Resistive touch screens designs use a sandwich design, with a soft top layer and a hard bottom layer separated by small spacer bumps. When the soft top layer is pressed, it deforms and contact is made between two thin films of conductive material (ITO) on the inside of the two structural layers.
The drawbacks are that the top layer has to be soft enough to deform easily when pressed, which makes it vulnerable to damage by scratching, and it cannot be used to provide the increasing important multitouch functionality. No current flows unless pressure is applied, there are no emi issues and resistive touch screens can be used with gloves and in any humidity conditions.
Crucially, however, as screen size increases, it becomes harder to maintain the tension of the top surface at the required level in order for the touch screen to work correctly. This has constrained its use to small screens. Capacitive touch screens have overcome many drawbacks of the resistive approach and have therefore become more popular. They have a robust, hard top surface and provide multitouch abilities.
However, the active matrix that provides the touch detection has a relatively high power consumption and this also constrains screen size, while creating potential interference issues whose solution requires careful design. This makes large capacitive screen solutions expensive. And the technology cannot be used with gloves or in high humidity environments.
Force sensitive touch screens QTC based touch screens use the same sandwich structure as resistive touch screens, with the exception that the air gap and spacer bumps are replaced by a screen printed, 6µm thick layer of QTC. By removing the air gap and replacing it with QTC, a material with a similar refractive index, the overall transparency is improved.
The top layer can be relatively hard, because QTC Clear can detect deflections of as little as a couple of microns from a force of as little as 5g. QTC based screens can also detect multi touches. QTC's properties mean that virtually no current flows unless a force is applied, which overcomes the drawbacks of capacitive designs that constantly draw current and require emi issues to be solved.
Importantly, there is no constraint on the size of a QTC based touch screen, so Force Sensitive touch screens can be made to any dimensions, opening up the market for a wide range of uses from desktop computers to automotive and from in store displays to interactive control interfaces. Manufacturers of resistive touch screens can easily upgrade to QTC Clear using their existing manufacturing procedures and equipment.
Capacitive touch screens can also benefit from the addition of a QTC Clear layer, with a key benefit being power saving. Because the matrix needs to be active in order to detect a touch, capacitive touch screens use power continually, which drains the battery in portable devices. A QTC Clear layer can act as a switch, activating the capacitive matrix only when a touch is detected. This provides a significant improvement in battery life.
Additional features that QTC provides are pressure sensitive input, variable line widths and more intuitive gaming interaction. Peratech has already licensed QTC Clear to a leading touch screen manufacturer and it anticipates that Force Sensing touch screens will be included in products being developed for the Christmas 2011 market. Author profile: Chris Lussey is Peratech's joint chief executive officer.
Clear force sensing material set to see touch screen functionality included in larger displays
4 mins read
Touch screens have proved to be a phenomenal success with smartphones and tablets, such as the iPad, changing the way that users interact with devices.
However, mass market use of touch screens has tended to be confined to smaller devices; there have only been a couple of attempts to deploy touch screens into larger devices, such as desktop computers, because the costs become prohibitive. However, touch technology specialist Peratech has developed a way of making touch screens that retains all the benefits of existing touch screen technologies, while overcoming their drawbacks.
In particular, the approach overcomes the constraints on larger screen sizes. Peratech has developed and patented a material called Quantum Tunnelling Composite (QTC). When a force is applied to this material, its resistance decreases in direct proportion to the force applied. This relationship makes the material suitable for use in a wide range of applications: from the replacement of switches to the detection of the lightest of touches.
The composite consists of a polymer which includes spiky nanoscale particles of metal – rather like a mediaeval mace. When a force is applied to the composite, the tips of the spikes move closer together and a quantum tunnelling effect occurs that enables a current to flow (see fig 1). When the force is removed, the particles move back to their original position, no current flows and the material's resistance returns to its previous value of almost infinity.
The force sensing ability of QTC can be used in many applications, but it has created a large amount of interest amongst mobile device developers, who are excited by the potential of adding another dimension to Human Machine Interaction – pressure. Because the harder QTC is pressed, the more current flows through it, the result is a smooth, analogue third dimension of input into the digital world of the mobile phone.
Thus, for example, pressing harder could make a menu scroll faster, a line wider or an avatar jump higher in computer games. Unfortunately, as QTC is made from metal particles in a polymer, it is opaque and this has presented a problem in making pressure sensitive screens for mobile phones. Peratech's initial solution to this problem was screen printing a series of QTC dots around the perimeter of the screen.
These dots detect the applied force as they are compressed against the screen's mounting – rather like a gasket. Having determined there was a market amongst mobile device developers for force sensing devices, Peratech continued to research into ways to create what was required – a clear version of QTC. And this has been achieved in the form of QTC Clear. This can be screen printed to form a thin layer that has minimal impact on transparency, being similar to that of a layer of indium tin oxide (ITO).
Not only does QTC Clear provide pressure sensitive 3d input with a proportional response, but it also breaks through the barrier that has until now kept touch screens restricted to small screen applications. Resistive touch screens designs use a sandwich design, with a soft top layer and a hard bottom layer separated by small spacer bumps. When the soft top layer is pressed, it deforms and contact is made between two thin films of conductive material (ITO) on the inside of the two structural layers.
The drawbacks are that the top layer has to be soft enough to deform easily when pressed, which makes it vulnerable to damage by scratching, and it cannot be used to provide the increasing important multitouch functionality. No current flows unless pressure is applied, there are no emi issues and resistive touch screens can be used with gloves and in any humidity conditions.
Crucially, however, as screen size increases, it becomes harder to maintain the tension of the top surface at the required level in order for the touch screen to work correctly. This has constrained its use to small screens. Capacitive touch screens have overcome many drawbacks of the resistive approach and have therefore become more popular. They have a robust, hard top surface and provide multitouch abilities.
However, the active matrix that provides the touch detection has a relatively high power consumption and this also constrains screen size, while creating potential interference issues whose solution requires careful design. This makes large capacitive screen solutions expensive. And the technology cannot be used with gloves or in high humidity environments.
Force sensitive touch screens QTC based touch screens use the same sandwich structure as resistive touch screens, with the exception that the air gap and spacer bumps are replaced by a screen printed, 6µm thick layer of QTC. By removing the air gap and replacing it with QTC, a material with a similar refractive index, the overall transparency is improved.
The top layer can be relatively hard, because QTC Clear can detect deflections of as little as a couple of microns from a force of as little as 5g. QTC based screens can also detect multi touches. QTC's properties mean that virtually no current flows unless a force is applied, which overcomes the drawbacks of capacitive designs that constantly draw current and require emi issues to be solved.
Importantly, there is no constraint on the size of a QTC based touch screen, so Force Sensitive touch screens can be made to any dimensions, opening up the market for a wide range of uses from desktop computers to automotive and from in store displays to interactive control interfaces. Manufacturers of resistive touch screens can easily upgrade to QTC Clear using their existing manufacturing procedures and equipment.
Capacitive touch screens can also benefit from the addition of a QTC Clear layer, with a key benefit being power saving. Because the matrix needs to be active in order to detect a touch, capacitive touch screens use power continually, which drains the battery in portable devices. A QTC Clear layer can act as a switch, activating the capacitive matrix only when a touch is detected. This provides a significant improvement in battery life.
Additional features that QTC provides are pressure sensitive input, variable line widths and more intuitive gaming interaction. Peratech has already licensed QTC Clear to a leading touch screen manufacturer and it anticipates that Force Sensing touch screens will be included in products being developed for the Christmas 2011 market. Author profile: Chris Lussey is Peratech's joint chief executive officer.
The force sensing ability of QTC can be used in many applications, but it has created a large amount of interest amongst mobile device developers, who are excited by the potential of adding another dimension to Human Machine Interaction – pressure. Because the harder QTC is pressed, the more current flows through it, the result is a smooth, analogue third dimension of input into the digital world of the mobile phone.
Thus, for example, pressing harder could make a menu scroll faster, a line wider or an avatar jump higher in computer games. Unfortunately, as QTC is made from metal particles in a polymer, it is opaque and this has presented a problem in making pressure sensitive screens for mobile phones. Peratech's initial solution to this problem was screen printing a series of QTC dots around the perimeter of the screen.
These dots detect the applied force as they are compressed against the screen's mounting – rather like a gasket. Having determined there was a market amongst mobile device developers for force sensing devices, Peratech continued to research into ways to create what was required – a clear version of QTC. And this has been achieved in the form of QTC Clear. This can be screen printed to form a thin layer that has minimal impact on transparency, being similar to that of a layer of indium tin oxide (ITO).
Not only does QTC Clear provide pressure sensitive 3d input with a proportional response, but it also breaks through the barrier that has until now kept touch screens restricted to small screen applications. Resistive touch screens designs use a sandwich design, with a soft top layer and a hard bottom layer separated by small spacer bumps. When the soft top layer is pressed, it deforms and contact is made between two thin films of conductive material (ITO) on the inside of the two structural layers.
The drawbacks are that the top layer has to be soft enough to deform easily when pressed, which makes it vulnerable to damage by scratching, and it cannot be used to provide the increasing important multitouch functionality. No current flows unless pressure is applied, there are no emi issues and resistive touch screens can be used with gloves and in any humidity conditions.
Crucially, however, as screen size increases, it becomes harder to maintain the tension of the top surface at the required level in order for the touch screen to work correctly. This has constrained its use to small screens. Capacitive touch screens have overcome many drawbacks of the resistive approach and have therefore become more popular. They have a robust, hard top surface and provide multitouch abilities.
However, the active matrix that provides the touch detection has a relatively high power consumption and this also constrains screen size, while creating potential interference issues whose solution requires careful design. This makes large capacitive screen solutions expensive. And the technology cannot be used with gloves or in high humidity environments.
Force sensitive touch screens QTC based touch screens use the same sandwich structure as resistive touch screens, with the exception that the air gap and spacer bumps are replaced by a screen printed, 6µm thick layer of QTC. By removing the air gap and replacing it with QTC, a material with a similar refractive index, the overall transparency is improved.
The top layer can be relatively hard, because QTC Clear can detect deflections of as little as a couple of microns from a force of as little as 5g. QTC based screens can also detect multi touches. QTC's properties mean that virtually no current flows unless a force is applied, which overcomes the drawbacks of capacitive designs that constantly draw current and require emi issues to be solved.
Importantly, there is no constraint on the size of a QTC based touch screen, so Force Sensitive touch screens can be made to any dimensions, opening up the market for a wide range of uses from desktop computers to automotive and from in store displays to interactive control interfaces. Manufacturers of resistive touch screens can easily upgrade to QTC Clear using their existing manufacturing procedures and equipment.
Capacitive touch screens can also benefit from the addition of a QTC Clear layer, with a key benefit being power saving. Because the matrix needs to be active in order to detect a touch, capacitive touch screens use power continually, which drains the battery in portable devices. A QTC Clear layer can act as a switch, activating the capacitive matrix only when a touch is detected. This provides a significant improvement in battery life.
Additional features that QTC provides are pressure sensitive input, variable line widths and more intuitive gaming interaction. Peratech has already licensed QTC Clear to a leading touch screen manufacturer and it anticipates that Force Sensing touch screens will be included in products being developed for the Christmas 2011 market. Author profile: Chris Lussey is Peratech's joint chief executive officer.
