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Film-Glass Touch Panels

Most commonly used touch panel. Exceptionally thin (0.84 mm) Gunze film-glass assembly delivers 88% transparency.

Highly transparent

Film-glass touch panels combine highly transparent glass and a low-reflective coating, resulting in exceptional transparency.

The low-reflective coating incorporates Anti-Reflection (AR)properties that improve transparency by changing reflecting light to transparent light.

Pen input durability

Gunze engineering has reduced the damage that repetitive use of the pen can cause to the transparent electrode layers.

High durability results in part from a transparent, conductive, resitive layer based on Gunze Indium Tin Oxide technology.

Easy data input

Using a pen to enter data is as fast and easy as writing with a pencil, making film-glass touch panels perfect for PDAs. With a cushioned pen point, low pen friction, and little required pen pressure, the pen glides easily across the panel.

Durable and reliable

Film-glass touch panels are available in models that are extremely durable even in rugged conditions, making these panels a good choice for applications such as vehicle navigation systems.

Resistance friction dispersion over the film surface (linearity) is within 1.5% when the pen point moves across the surface reciprocally for 100,000 times with 250gf weight at the pen point.

Rugged reliability

Touch panels mounted on vehicles undergo severe environmental challenges. Gunze film-glass touch panels minimize damage that can result from a number of environmental causes:

Electrical resistance at the transparent electrodes

Fading color of plastics

Deterioration of electric wires

Variations of temperature and humidity

Fingerprint reduction

Fingerprints on the touch panel surface can be an annoyance, especially in car navigation systems. Gunze film coating technology makes fingerprints inconspicuous by reducing the appearance of grease left on the panelÕs surface.

The fingerprint reduction feature is available on all Gunze Anti-Glare (AG) touch panels and on other types of Gunze touch panels by request.

Figure 1. Film-glass (standard) type cross-section
Click on drawing for larger view.

Newton rings

Newton rings (NRs) are an optical interference pattern caused by the reflection of light between two surfaces — a spherical surface and an adjacent flat surface. These rings can appear on film-glass touch panels when there is a gap between the film and the glass. Gunze touch panel technology prevents NRs by means of a patented anti-Newton ring (ANR) treatment applied to the inner side of the film, under the electrode layers.

Figure 2. ANR treatment
Click on drawing for larger view.

Color bias

Gunze film-glass touch panels enable LCDs to display a true color range, avoiding the yellow or blue color bias that is present in other transparent touch panels.

The crucial wave length to achieve transparency is 550 nm. At the highest transparency, blue color has a peak wave length of around 510 nm, but it tends to weaken at 550 nm, at which point the conductive layer takes on a yellow hue. Gunze has developed a film that does not have a peak wave length, while retaining high transparency.

Figure 3. Correlation of color bias and transparency on touch panel

Film surface treatment

To prevent scratches, Gunze adds a protective hard, solid resin coating to the touch film.

In addition, the anti-glare (AG) surface coating contains a light dispersing agent that reduces reflection caused by light sources such as fluorescent lights, while retaining a clear image.

Thinness

Gunze film-glass touch panels are extremely thin, making them ideal for mobile and wearable applications.

Gunze glass panels are available in widths as thin as 0.55 mm, with a total film-glass thickness of only 0.84 mm.


Table 1. Touch panel transparency
Construction		Upper electrode film
		Clear				AG (HAZE 5%)
		With AR	Without AR	With AR	Without AR	With AR	Without AR
Lower electrode glass	Super transparent:	88%	86%	88%	—	87%	84%
	Highly transparent:	85%	83%	85%	—	84%	81%
	Standard glass:	82%	80%	82%	—	81%	78%
HAZE (for reference)		< 1%		typ. 3%		typ. 10%
Notes: Typical figures using a glass panel of 0.7 mm thickness by JIS K7361-1. HAZE rate is obtained when the transparency rate is measured by JIS K7361-1. ANR = Anti-Newton's Ring (Newton's ring-proof process). AR = Anti-reflection.


Table 2. Film-glass thickness
Glass thickness (mm)	Gross thickness of touch panel (mm)	Maximum outer shape of touch panel
0.55	0.84 + 0.2	type 8.4 or under
0.70	0.99 + 0.2	type 10.4 or under
1.10	1.39 + 0.2	type 12.1 or under
1.85	2.14 + 0.2	above type 12.1
Note: Use a glass that is of a thickness appropriate to your application. Thicker glass is better for rugged applications.

Flexible Connectors

Many types of connectors are available from Gunze, from low-cost, ink-printed connectors to precisionstamped metal connectors that are very durable and that can withstand many eject/insert cycles. Environmentally friendly Halogen and tin-free tails are available.


PET Ink connector	PET Metal connector	PI Metal connector


Table 3. Connector comparison
Capacity	Ink-printed type	Metal type
Base film	PET	PET	Polyimide
Circuit silver:	+ carbon ink cu	+ lead-plated cu	+ gold-plated
Circuit pitch:	up to 1.00 mm	up to 0.5 mm	up to 0.5 mm
Stamping:	+ 0.15 mm	+ 0.1 mm	+ 0.1 mm
Eject/Insert	fair to very good	very good	very good
Bending	more than R2	more than R2	more than R1

4-wire and 8-wire panels

Unlike early touch panels that used a simple matrix detection method in which two transparent electrodes crossed each other at right angles, Gunze touch panels use an analog detection method that can detect handwritten characters. These 4-wire analog touch panels have 4 wires that connect to 2 parallel electrodes on each X and Y axis.

Gunze 8-wire touch panels have a total of 8 wires that connect 2 parallel electrodes on each X and Y axis.


4-wire	8-wire

Figure 4. 4-wire and 8-wire detection method comparison
Click on drawing for larger view.

8-wire touch panels are a good choice for systems that include a 6-inch or larger display capable of displaying resolutions higher than SVGA, because precise detection is more important on larger displays than on smaller ones. Gunze's 8-wire panels include an autocalibration feature, in which the controller measures and adjusts the variance of electric resistance according to the conditions in use when the controller's switch is turned on and restarted from sleep mode.

Figure 5. Positioning data in changing voltage
Click on drawing for larger view.

Detection works as follows:

Positioning data on the X axis is detected by applying voltage to an X axis electrode and using the Y axis as a voltage detector. Similarly, positioning data on the Y axis is detected by applying voltage to a Y axis electrode and using the X axis as a voltage detector. Realtime detection is obtained as these processes are alternated, locating coordinates on the X and Y axes.

For example, if 0-5 V of direct current is applied to a 4wire panel, because of resistance on the wiring area the voltage at the effective area becomes 0.3 V-4.7 V. Therefore, when a 10-bit controller is used, only 70-960 data points out of 1024 segmentation data can be detected. On the other hand, an 8wire panel can use all 1024 segmentation data points. An 8wire panel reads the touch panel's reference voltage and adjusts the pressed position data to become 0-1024 data points. For example, if the pressed position is 2 V, reference voltage is:

xLref=20 and xRref=1000 points.

4-wire: 2 (V) / 5 (V) x 1023 (10 bit) = 409 points

8-wire: (409-20) / (1000-20) x 1023 (10 bit) = 406 points

Auto Calibration is a function whereby the controller measures and adjusts the variance of electrical resistance according to the present conditions. Software accounts for voltage and resistance variations and reports a position accordingly.

User Calibration accomplishes the same thing manually.

Film-Glass Touch Panels

Table 1. Touch panel transparency

Table 2. Film-glass thickness

Table 3. Connector comparison