On the other hand, the old resistive touch seems to drop behind the multi-touch war, until Stantum hit the web with its new resistive multi-touch screens. But Stantum is not alone. As far as I know, two more companies are also working on resistive multi-touch technologies - SiMa systems and Touchco. I introduced SiMa Systems before, so let me show Touchco in this post.
Touchco is a new multi-touch tech. company to commercialize IFSR (Interpolating Force-Sensitive Resistance) technology. The key technology was introduced at the Microsoft Research Summit (Unmouse Pad) and SIGCHI2009 (IMPAD). Although Touchco's multitouch is categorized into resistive touch, detailed technology is a little different. Exactly speaking, Touchco's system generates analogue pressure map while Stantum system gives binary (contact or not) one.
It's mainly because Touchco uses force sensing resistors as major sensing components. The FSR, as the name implies, changes its internal resistance according to the applied force (pressure). Therefore, Touchco multitouch pad can sense pressure by checking resistance.
Features and specifications of the company’s technology are:
- Multi-touch finger tracking: Current trend is toward multi-touch interfaces
- High-resolution pen tracking: Needed for high-end art/design/engineering applications
- Pressure sensing / force imaging: Allows novel applications and more natural human-computer interaction
- Low cost: Uses existing printing techniques and inexpensive electronics
- Low power usage: Necessary for mobile applications
- Scalability: Can be used on very small or very large devices
- Flexible: Works on flat or curved surfaces
- Can be transparent: For touch screens
- Thickness: 0.01" (0.25 mm)
- Speed: 60 Hz to 500 Hz
- Resolution: 100 dpi* (254)
- Power Source: USB
- Power Usage: 1mA
- Pressure Range: 5 g - 5 kg**
- Production Cost: $10/sq. ft. in high volume
- Form Factors:
- 21" x 12" large desktop sensor
- 11" x 8.5" medium desktop sensor
- 3" x 2.5" mobile device sensor
- 14" diameter large drum sensor
- 8" diameter small drum sensor
It's good to get very fine multitouch pressure information, but I roughly guess that the IFSR technique has following two issues:
First, getting pressure information might need some computing power. Since the sensor gives voltage measurements as raw outputs, a processor should calculate resistance values from the voltage measurements. Then, this resistance values are converted into pressure values. The final pressure information is what remaining data processing algorithm can use. On the contrary, Stantum' system simply scans a sensor matrix to determine if a user touches specific points. The only additional step before touch data processing is a very simple binarization process.
Second is the integration with displays. The company clams that it can be transparent, I am not sure if FSR can be made transparent.
Anway, welcome to multitouch, Touchco.
PS: I didn’t mention Motorola’s pressure sensitive multi-touch panel in this post due to lack of information
Updated November 16, 2009
Charley has left a helpful note. The IFSR sensors usually run at between 80 and 200 frames per second. The speed of the sensors is commercially acceptable. The required frame rate for pen computing is around 133 Hz (p.18 of Microsoft’s PowerPoint document). In addition, Touchco showed off a transparent version at SIGGRAPH2009.
On the other hand, Touchco adds two more demonstration video clips on YouTube. The first one is an integrated version of the IFSR sensor and an e-ink display. The second video shows the writing and drawing demonstration.