The Relationship between Activation Force and Sensitivity for A Resistive Touch Screen

Thanks to your kindness and constant support, PenMount has accumulated so many market experiences that make PenMount grow. PenMount brings the most stable and reliable solutions to customers, and provides the customers with efficient before- and after-services. It has always been PenMount's goal to rapidly and accurately fix the problems that occur to customers.

A resistive touch screen operates by the "force" applied on it. PenMount occasionally receives requests from customers asking if it is possible to adjust the sensitivity of a resistive touch screen through the controller. To this question, we'd like to raise another question in reply: what has decided the sensitivity of a resistive touch screen? Is it the controller or the touch screen? In this issue of PenMount Bulletin, we will make it clarified that the operation of a resistive touch screen actually depends on its constituent materials and its design.

 

A touch screen operates by the force applied on it. The force that makes the touch screen work is the so called "sensitivity" of a touch screen. In the following, we will detail "sensitivity" in three phases :

1. See the figure below. It shows the state before force is applied to the touch screen. The finger is simply placed on the touch screen. The finger contacts the touch screen surface, but ITO film and ITO glass haven't contacted each other. No action is triggered since the two electrical conductive layers aren't pressed together and no voltage gradient is caused.

 

 

2. When force is gradually applied to the touch screen, the upper ITO film layer is pressed but isn't fully pressed to the bottom ITO glass, and therefore the ITO film and ITO glass are only slightly contacting each other (due to uneven force application). The rise and fall of resistance are great at this moment. This is the moment when signals haven't reached stability, and also the moment some users might mistakenly think as a time to adjust the sensitivity. We'd like to clarify that if the controller receives and sends out these unstable signals, the touched position detected will be wrong. However, PenMount has overcome such problem by filtering the unstable signals when signals haven't got stable yet.

 

 

3. When the force applied increases to certain extent, say 10 g or more, the ITO film and ITO glass are steadily contacted and signals are stable. The controller receives normalized signals.

 

A regular touch on the touch screen is usually a combination of the 3 phases mentioned above. For example, the line drawn on the touch screen with your finger pulp breaks easily. This is mainly due to 2 reasons. On one hand, your finger pulp, the contact area, is big. The bigger the contact area is, the smaller the pressure is. On the other hand, the angle of your operating finger isn't always consistent. Whether due to the incomplete contact between ITO glass and ITO film as mentioned in (B) or due to lack of contact between ITO glass and ITO film as mentioned in (A), PenMount drivers ensure you the best touch experiences by the optimized sensitivity of the touch screen.

PenMount series of touch software and hardware are designed to meet market demands. If customized specifications are needed, we are always ready and available to help customer to complete their project. For more PenMount controllers and drivers information,  contact Omni Display

Resistive Multi-Touch Technology

Conventional resistive touch screens are unable to detect more than one contact at one time whether it concerns a 4-, 5-, or 8-wire. In 2008, AMT broke through this limit by presenting Multi-Finger to the market. MF makes it possible to detect and track up to 12 contacts on a touch screen at one time. However, starting from last year, you might have heard about other resistive technology that supports multi touch input, they are the AMR (Analog Matrix Resistive) and DMR (Digital Matrix Resistive) touch screens. They are both developed based on 4-wire resistive technology. In this issue of AMT news express, we will share with you the advantages and disadvantages and also the applications of these resistive touch screens (whether dual-touch or multi-touch).

Let's start with the touch theory of AMR and DMR. AMR and DMR are both constructed based on the standard 4-wire resistive structure. The coordinate axes X and Y are laid out onto each upper and bottom transparent electrically conductive film (ITO Film) and conductive glass (ITO Glass). The upper and bottom electrodes are separated by many dot spacers between them. When we apply force to the upper electrode with a finger, stylus, or other medium, the two electrical conductive layers are pressed together and voltage gradient is caused, and signals indicating voltage change are sent to controller through buses, so that controller can calculate the coordinates of the position that is touched.

For AMR touch screens, X and Y coordinates are laid out to the electrically conductive layers by the interval of about 1 cm. These coordinates form a lot of zones when the upper and lower layers are stacked together. Each zone is a 4-wire resistive touch area, after we apply force to these zones with our fingers, styli or other media, signals are sent to the controller, then the controller can calculate the coordinates of the touched position according to the proportion of the voltage dropped. As to the question how many touches can be operated simultaneously, it depends on the speed of the controller.

DMR divides the touch screen to even smaller zones, it is divided by 1mm~3mm intervals. When a zone is touched, it will be activated to work similarly to an ON/OFF switch. Then the digital signal indicating ON or OFF is sent to the controller. The controller will calculate the coordinates of the position touched.

Unlike DMR and AMR, AMT's Multi-Finger is developed based on 5-wire resistive touch technology. Its upper conductive film (ITO Film) is divided to multiple zones. As each touch zone functions like an individual analog touch screen of single touch input, the entire touch screen accepts simultaneous multiple touches. A Multi-Finger touch screen can be divided to 2 zones or up to 12 zones with each zone size and zone position definable by customer's application.

AMR and DMR share the advantage that touch zones can be made very small so that software applications have more flexibility. However, the applications are more practical for small-sized products due to material readiness and production complexity. MF, on the contrary, although has less touch zones than AMR or DMR, it requires much less circuit lines than AMR or DMR and is therefore a good choice for products of bigger sizes or for the products with defined software application, such as the industrial use to reconfirm safety.

MF is currently in mass production, sizes available from 3" to 22". Each touch zone size and zone position is definable for you. We'd be happy to discuss with you about developing the appropriate MF touch screens for your products. Should you have any question and requirement for MF products, please contact Omni Displays LLC.

Advance to the future with Omni Displays touch solutions.

5-Wire Analog Resistive Touch Sensor TR-5000 ( 2 in one )

Whereas people have long been looking for both resistive and capacitive touch panels in precisely the identical dimension, it is omnidisplays firm commitment to bring to market a unique 2-in-1 product portfolio. Our 2-in-1 touch panel devices offer the greatest advantages of not only providing the high compatibility and stability of the resistive sensor, but also the capacitive sensor’s unique characteristics such as being workable in very handing environments, high anti-scratch properties and burn resistance.
Our 2-in-1 product portfolio features touch related product makers with one mechanical design available for both resistive and capacitive sensors, benefiting customers with twice the application field. By merely replacing the resistive sensor with the same size capacitive senor and controller, while maintaining identical utility and device drivers, customers can use their 2-in-1 sensors to work on multiple operating platforms simultaneously.

Size	PartNumber	Out Area		View Area		Active Area		Glass	connector	Tail		Drawing
		X	Y	X	Y	X	Y	thickness		Length	Pitch
		(mm)	(mm)	(mm)	(mm)	(mm)	(mm)	(mm)		(mm)
12	S5-121E18P5L3AS1	271.3	205.7	250.9	189.4	248.9	187.4	1.8	Latch	100		1/11/2006
15	S5-151E28P5L3AS1	332.9	248.9	311	233	310	232	2.8	Latch	100		1/11/2006
17	S5-171E28P5L3AS1	365.4	290.2	341	273.4	340	272.4	2.8	Latch	100		1/11/2006
19	S5-190E28P5L3AS1	406.3	323.4	381.9	306.6	380.9	305.6	2.8	Latch	100		2006/1/11

Capacitive Touch Sensor TC-7100 Anti-Glare ( 2 in one )

Our 2-in-1 touch panel devices offer the greatest advantages of not only providing the high compatibility and stability of the resistive sensor, but also the capacitive sensor’s unique characteristics such as being workable in very handing environments, high anti-scratch properties and burn resistance.
Our 2-in-1 product portfolio features touch related product makers with one mechanical design available for both resistive and capacitive sensors, benefiting customers with twice the application field. By merely replacing the resistive sensor with the same size capacitive senor and controller, while maintaining identical utility and device drivers, customers can use their 2-in-1 sensors to work on multiple operating platforms simultaneously.

Size	PartNumber	Out Area		View Area		Active Area		Glass	connector	Tail		Drawing
		X	Y	X	Y	X	Y	thickness		Length	Pitch
		(mm)	(mm)	(mm)	(mm)	(mm)	(mm)	(mm)		(mm)
12	SC-121E30P5L4AE1	271.3	205.7	250.9	189.4	248.9	187.4	3	Latch	100		2006/1/12
15	SC-151E30P5L4AE1	332.9	248.9	311	233	310	232	3	Latch	100		1/12/2006
17	SC-171E30P5L4AE1	365.4	290.2	341	273.4	340	272.4	3	Latch	100		1/12/2006
19	SC-190E30P5L4AE1	406.3	323.4	381.9	306.6	380.9	305.6	3	Latch	100		1/12/2006

Capacitive Touch Sensor TC-7100 Polish ( 2 in one )

Whereas people have long been looking for both resistive and capacitive touch panels in precisely the identical dimension. Our 2-in-1 touch panel devices offer the greatest advantages of not only providing the high compatibility and stability of the resistive sensor, but also the capacitive sensor’s unique characteristics such as being workable in very handing environments, high anti-scratch properties and burn resistance.
Our 2-in-1 product portfolio features touch related product makers with one mechanical design available for both resistive and capacitive sensors, benefiting customers with twice the application field. By merely replacing the resistive sensor with the same size capacitive senor and controller, while maintaining identical utility and device drivers, customers can use their 2-in-1 sensors to work on multiple operating platforms simultaneously

Size	PartNumber	Out Area		View Area		Active Area		Glass	connector	Tail		Drawing
		X	Y	X	Y	X	Y	thickness		Length	Pitch
		(mm)	(mm)	(mm)	(mm)	(mm)	(mm)	(mm)		(mm)
12	SC-121E28P5L5PE1	271.3	205.7	250.9	189.4	248.9	187.4	2.8	Latch	100		2006/1/12
15	SC-151E28P5L5PE1	332.9	248.9	311	233	310	232	2.8	Latch	100		1/12/2006
17	SC-171E28P5L5PE1	365.4	290.2	341	273.4	340	272.4	2.8	Latch	100		1/12/2006
19	SC-190E28P5L5PE1	406.3	323.4	381.9	306.6	380.9	305.6	2.8	Latch	100		1/12/2006