Touch-typing with a stylus (abstract)

Abstract

Keyboards are a vital part of today’s computers. Although keyboards are somewhat butky, they are well suited to PCs (even portable laptops) and workstations. In the future of Ubiquitous Computing [3], pocket-sized and wall-sized compu’krs will be common. A keyboard is not very suitable for these sizes of computers. Thus many manufacturers are providing electronic pens or styli (we use the two terms interchangeably) as the primary input device for computers. A stylus is attractive because it works very well over the entire range of sizes. However, it is not very convenient for text entry. The state of the art is to print characters, with hxed entry recommended to improve aecumcy [1]. This is slow and error prone [2]. This suggests that a major impe&ment to the widespread use of styli is the problem of finding a convenient way to enter text. There is an analogy betwtwn keyboards and styli. Keyboarda can be used with no training: the letters can be tapped out one-by-one using hunt-and-peck. This is similar to what is currently done with styli. No new training is required, and letters are printed one-by-one. However, unlike styli, keyboards have a “growth path.” Whh practice, hunt-and-pek with two fingers can become faster than handwriting. If even higher speeds are desired, then keyboard users can learn touch-typing. Touch-typing not only achieves high speeds, it also enables “eyes-free” operation, that is, the ability to type without having to look at your hands. his suggests that the solution to the problem of stylus text entry requires developing an analogue of touch-typing. Our approach to developing touch-typing for a stylus is based on introducing a special alphabet of unistrokes. Like touch-typing for keyboards, unistrokes have to be learned. Unistrokes have the following advantages over ordinary pMting: Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is givan that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or epecific permission. ; 1993 ACM 0.8979 j-~75-~/93/0004/0520 . ..$j .50 ● They are designed somewhat like error correcting codes. When written sloppily, they can still be distinguished from one another. ● Each unistroke is a single pen-down/pen-up motion, hence the name unistroke. Not only does this mean that recognition cannot have segmentation errors (that is, errors in determining which sets of strokes belong to a single multi-stroke letter), but it means that letters can unambiguously be written one on top of another. Thus unistrokes can he entered in a small box just big enough to hold one letter. ● The unistrokes associated with the most common letters (’e’, ‘a’, ‘t’, ‘i’, ‘r’) are all straight lines, and hence are fast to write. The unistroke design is being evaluated by having users send several e-mail messages per day using a stylus frontend to the Unix mail program. Based on measurements from this program, it appears that unistrokes may be able to support an entry rate as high as 3.5 letters/see (touch typing is typically 6-7 letters/see). The video gives the motivation for unistrokes, briefly shows text entry using a conventional pen-based interfaee [11, discusses the unistroke alphabet and how it was designed to be easy to learn, and then shows a skilled writer using unistrokes.