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Tip-on-Glass; Still the Primary Problem to Solve

We keep hearing that the feel of writing (or drawing) on glass is just “not right”. *Research has continually pointed to this problem. We intuitively know there is an issue, but even after ten years of talking about it, I did not understand how serious this issue is and how it is negatively impacting broad adoption of digital pens.   Reading the research, combined with recent testing with various nibs (tips) and first surface materials has led me to some strong conclusions;  The solution is not to be found in the nib material, but will require changes to the writing surface itself.   My goal is to shift product development priorities from serving viewers to serving doers who need a really good pen based product.

For those of us who want to see the pen fulfill the promise and to achieve its potential to drive device sales, this issue should take on an urgent even mono focused effort.  

The “tip-on-glass” problem even if subconscious, affects everyone who has a pen enabled system. We start out with grand visions for how this will change our lives but end up disappointed when we feel more comfortable grabbing a paper notebook and ink pen.   As of now customers are sadly not using the pen as we would like and this will negatively impact device sales and slow market adoption of writing first devices, 2 in 1 / detachables. 

The “tip-on-glass” problem summary:

With all the various nibs being offered, most of us pick one that is smooth but not too slippery. The most popular are the soft nibs that create an increased amount of friction on the screen.   Unfortunately the smooth glass offers no real feedback to the hand, which means we must keep “eyes-down” on the screen when writing to accurately internalize movement and tip position. One of the key benefits of writing with a pen on paper is the indentation that a stack of paper offers and the ability to just feel the tip movement. This feedback enables us to think while we write, look people in the eye while we take notes, and with a periodic glance confirm ink is going where we want it on the page. The “eyes-down” requirement of writing on glass is both distracting and steals cognitive bandwidth from the task at hand. 

Background:

“According to studies, tactile feedback allows for superior discrimination- when successive data needs to be rapidly resolved, the feel of touch is about five times faster than vision.”   Ambient Touch:  Designing Tactile Interfaces for Handheld Devices, Ivan Poupyrev, Shigeaki Maruyama, and Jun Rekimoto

Feedback through our fingers defines the writing experience and is critical to our ability to think while writing.  The hand is an ultra-sensitive, high speed, high resolution receiver that requires a rigid pen and tip to sense movement quickly and accurately.  The soft tips have the net effect of a shock absorber dampening feedback into a smooth, but meaningless representation of writing friction.  Even worse are the wobbly tips and pen pressure mechanisms which introduce distorted feedback that confuse the messages to our brains.  When we look up to think about a problem or make eye contact while taking notes our pen begins to drift. Any attempt at holding the pen tip in a stationary position takes a concentrated effort.

The meaningful events that provide feedback are uniquely “change” based.   We sense change in direction, starting, stopping, tip-up, tip-down, acceleration and deceleration.  Our fingers sense the change in the associated vibrations including the frequency, compression and tension associated with each change. In the period of one second we can sense dozens of changes covering about 30-50 mm.   If these tactile changes are distorted or not transferred correctly we become frustrated. We end up paying more attention to writing than we do to our focused task.

Solution:

Please understand, I love my Surface Pen and will not surrender the flexibility it gives me however, when focus is required, I still maintain a journal in pen and paper. To understand the issue I have tried more than 20 surface treatments and films in combination with a similar number of different tips.   When I speak of optimizing screens for “writing”, I have several close friends who politely remind me of the industry priorities for optimizations that improve “watching”.   Yet here we are, expensive pens, expensive glass… amazing for watching, but wrong for writing. If we are serious about building a writing first device, then we will adjust our priorities.

As an industry we have fallen short on the ability of our digital pens to deliver a true and natural writing experience. Demand is waiting in education, business, China, and many specialty markets like healthcare, insurance and design graphics.

Soft nib design strategies will continue to miss the goal.   The solution must incorporate a screen surface material that matches the indentation AND friction of a pad of paper.   The solution is actually simple if we can get past the idea of a first surface with new priorities.    

Rick Seger works for the advancement of digital pens and as a Technology Advisor at Tactus Technology,www.tactustechnology.com. Tactus is a materials sciences company innovating solutions for tactile interfaces. He is based in Austin, TX and can be reached at Rick@tactustechnology.com.

*Research:

(1) Annett, M., Anderson, F., Bischof, W. F., & Gupta, A. (2014, May). The pen is mightier: understanding stylus behavior while inking on tablets. In Proceedings of the 2014 Graphics Interface Conference (pp. 193-200). Canadian Information Processing Society.

“Many participants felt that “”there was not enough friction between the pen and screen to feel natural“”. The importance of surface texture to participants counters current thinking about tablet surfaces, i.e., that they should be made of glass because it is glossy, slick, and visually appealing. If stylus-based devices are to be taken seriously as pen and paper replacements, the texture of a device’s surface and materials the stylus nib is composed of should be optimized to evoke familiar feedback patterns for the user and encourage natural movement instead of hindering it.”

(2) Mohr, A., Xu, D. Y., & Read, J. (2010). Evaluation of Digital Drawing Devices with Primary School Children-A Pilot Study. In Proc. of ICL.

“We observed that children had some difficulties of handling the input devices. For example, the stylus was difficult to grasp as it was often slippery on the tablet surface…..In the questionnaire, this problem was mentioned by 10 children (out of 53). They reported that the stylus were hard to handle and draw with.”

(3) Sun, M., Ren, X., Zhai, S., & Mukai, T. (2012, August). An investigation of the relationship between texture and human performance in steering tasks. In Proceedings of the 10th asia pacific conference on Computer human interaction (pp. 1-6). ACM.

“Many users complain that a tablet or display is too slippery for writing characters or drawing pictures on…..Imagine that you walk from one place to another. Compare the movement times when you walk on ice to when you walk on an asphalt road. Obviously, the time taken to walk on ice is much longer than the time taken to walk the same distance on an asphalt road. People walk more comfortably with ground friction. However, when people walk on ice, they tend to slip since the coefficient of friction is very small, maybe even as low as zero.”

(4) Annett, M., & Bischof, W. F. (2015, June). Hands, hover, and nibs: understanding stylus accuracy on tablets. In Proceedings of the 41st Graphics Interface Conference (pp. 203-210). Canadian Information Processing Society.

“With most device manufacturers utilizing non-textured glass for the surface ofthe display, it becomes easy to lose control of the stylus. While these materials allow for vibrant, aesthetically-pleasing displayed content, they do not provide the tactile feedback or friction necessary for inking. Increased effort is thus needed to ensure that the stylus lands, and moves across the screen, as desired.”

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