One-key Keyboard: A Very Small QWERTY Keyboard Supporting Text ...
One-key Keyboard: A Very Small QWERTY Keyboard Supporting Text Entry for Wearable Computing Seoktae Kim
Minjung Sohn Jinhee Pak Woohun Lee Korea Advanced Institute of Science and Technology 373-1, Kuseong-dong, Yuseong-gu, Daejeon 305-701, Korea {seoktaekim, sohnminjung, jenny808, woohun.lee}@kaist.ac.kr +82-42-869-4559
ABSTRACT
sufficient wearability, input efficiency, and learnability.
Most of the commercialized wearable text input devices are wrist-worn keyboards that have adopted the minimization method of reducing keys. Generally, a drastic key reduction in order to achieve sufficient wearability increases KSPC (Keystrokes per Character), decreases text entry performance, and requires additional effort to learn a new typing method. We are faced with wearability-usability tradeoff problems in designing a good wearable keyboard. To address this problem, we adopted a new keyboard minimization method of reducing key pitch and have developed the One-key Keyboard. The traditional desktop keyboard has one key per character, but One-key Keyboard has only one key (70mmX35mm) on which a 10*5 QWERTY key array is printed. One-key Keyboard detects the position of the fingertip at the time of the keying event and figures out the character entered. We conducted a text entry performance test comprised of 5 sessions. The participants typed 18.9WPM with a 6.7% error rate over all sessions and achieved up to 24.5WPM. From the experiment’s results, the One-key Keyboard was evaluated as a potential text input device for wearable computing, balancing wearability, social acceptance, input speed, and learnability.
The most common user interfaces for a wearable computer that are suggested or commercialized in general are the wrist-worn keyboards such as Halfkeyboard, WristPC keyboard, Frogpad, Stick Keyboard and so on. These input devices attempt to minimize the size by decreasing the number of keys. In order to input texts with only a few keys, multitapping or key combination has to be adopted. It is possible to reduce the number of keys by using multitapping system as Stick Keyboard did. However, the input speed decreases significantly due to the increase of KSPC (keystrokes per character). In case of Halfkeyboard and WristPC keyboard, the input efficiency is rather exceptional, but it is unnatural to wear on the wrist in daily life because of the size. In this research, we focused on suggesting a way to minimize the QWERTY keyboard without increasing KSPC. If this is possible, it can have high qualities of sufficient wearability, input efficiency, and learnability. One way to minimize a keyboard without increasing KSPC is to reduce the key pitch of a desktop QWERTY keyboard instead of reducing the key numbers. If a smaller size of keyboard can be made with reduced the key pitches, wearability will be improved. However, the input error will increase while the input speed decreases because of the thickness of human fingers. Since wearability and text entry performance are in trade-off relationship, it is important to find the optimal balancing point.
Author Keywords
Wearable Computing, Text entry, Keyboard. ACM Classification Keywords
H5.2 [Information Interfaces and Presentation]: User Interfaces –Input devices and strategies
Examples of minimizing QWERTY keyboard by reducing key pitch are Graphic keyboard for PDA and mini-QWERTY keyboard of Targus and Dell. The former uses a stylus to input a key with about 4mm key pitch. The latter inputs the text by holding the keyboard with two hands and pressing the buttons (about 7mm key pitches) with two thumbs. According to the previous research of measuring input efficiency, the input speed of graphic keyboard for PDA was 13.64WPM (only one session) with 4.11% error rate. With mini-QWERTY keyboard, the input speed is 60.03WPM and the error rate is 8.32% after 20 times of 20-minute sessions. Concerning the input speed, mini-QWERTY keyboard shows far better performance than graphic keyboard.
INTRODUCTION
A keyboard in the wearable computing environment should have sufficient wearability, enough fast input speed, and low error rate when users input texts. It should also be easy for general users to learn without any special training, and use marketable technologies. Due to the difference between the wearable computing environment and the desktop computing environment, the requirements mentioned above easily contradict each other, and it is not easy to find a meaningful balancing point. Hence, it is difficult to find an input device which equally satisfies
In this study, we tried to develop a keyboard that can be worn easily on the wrist and can be used with one hand, considering the wearable computing environment where text input device should have sufficient wearability as well as the maximum degree of freedom of hands.
OZCHI 2006, November 20-24, 2006, Sydney, Australia. Copyright the author(s) and CHISIG Additional copies are available at the ACM Digital Library (http://portal.acm.org/dl.cfm) or ordered from the CHISIG secretary ([email protected]) OZCHI 2006 Proceedings ISBN: 1-59593-545-2
305
Moreover, we worked to establish an efficient text input method that does not need any additional instruments such as a stylus due to the active wearable computing environment. WEARABILITY OF MINIMIZED KEYBOARD EXPECTATION OF SOCIAL ACCEPTANCE
AND
Unlike the desktop computing environment, people have to wear a keyboard in wearable computing environment. A keyboard has to not only have good input efficiency but also be worn comfortably and used in daily life without any difficulty. The keyboard size will be a crucial factor in deciding wearability and social acceptance. We conducted an experiment to investigate what effect a keyboard size has on wearability and social acceptance. The sizes of the keyboard model for the test are set into six levels as seen in figure 2 based on the specification of WristPC (148*65*13mm) and Halfkeyboard (145*80*18mm). The width is respectively 50mm, 70mm, 90mm, 110mm, 130mm, 150mm and height is 1/2 of the width. The thickness of prototype is all controlled to 7mm. Each model is worn with the shape attached on wrist band.
Figure 1. Minimized keyboard models for evaluating wearability and social acceptance (From top-left to bottomright, a width of keyboard is 50mm, 70mm, 90mm, 110mm, 130mm, and 150mm.) 7.0
Mean ratings (1~7).
Twelve college students (6 males, 6 females) participated. The average age of participants was 23.8 years: 24.2 for male and 23.3 for female. The experiment conductor randomly selected one of the keyboard models and let the participant put it on and evaluate the “wearability: how comfortable to wear” using 7 point rating scale (1 point: very uncomfortable, 4 point: neutral, 7 point: very comfortable). With the same setting, a participant also evaluated the “social acceptance: is it acceptable to wear it in daily life?” using 7 point rating scale (1 point: very unacceptable, 4 point: neutral, 7 point: very acceptable). Furthermore, we prepared the commercialized WristPC keyboard and Halfkeyboard for a participant to evaluate wearability and social acceptance using the same setting as mentioned above. The results are given in Figure 2.
Wearability Social acceptance
6.0 5.0 4.0 3.0 2.0 1.0 50mm
70mm
90mm 110mm 130mm 150mm
H/K
W/K
Keyboards
!
Figure 2. Experiment results for wearability and social acceptance of minimized keyboard models, Halfkeyboard, and WristPC keyboard. (H/K: Halfkeyboard, W/K: WristPC keyboard)
experiment result, the size of a keyboard should be smaller than 90mm, approximately the size of a name card. We confirmed that 70mm and 50mm keyboards are satisfactory in wearability and social acceptance.
As shown in Figure 2, wearability and social acceptance of WristPC keyboard are rated 3.8/7.0(StDev: 1.2) and 2.6/7.0(StDev: 1.1). Those of Halfkeyboard are rated 3.2/7.0(StDev: 1.2) and 2.1/7.0(StDev: 0.7). WristPC keyboard which is designed as a wrist-worn type shows rather convincing result in wearability, yet considerably low result in social acceptance. In the case of Halfkeyboard, both wearability and social acceptance are rather low.
CONCEPT OF ONE-KEY KEYBOARD
One-key Keyboard literally means text input device which has only one key. In case of traditional keyboard, while one character is assigned to one key, One-key Keyboard displays whole QWERTY keyboard layout of characters in one keyboard. This allows the key space to be reduced dramatically. It is a mechanism to input pertinent characters by sensing the finger’s position on the letter plate and pressing the switch which is whole keyboard.
In the case of the keyboard models that we used in this research, wearability and social acceptance are in inverse proportion to the size. According to within-subject oneway ANOVA test, it is confirmed that the size of the keyboard has a significant effect on wearability (F(5,55)=26.307, p
Minjung Sohn Jinhee Pak Woohun Lee Korea Advanced Institute of Science and Technology 373-1, Kuseong-dong, Yuseong-gu, Daejeon 305-701, Korea {seoktaekim, sohnminjung, jenny808, woohun.lee}@kaist.ac.kr +82-42-869-4559
ABSTRACT
sufficient wearability, input efficiency, and learnability.
Most of the commercialized wearable text input devices are wrist-worn keyboards that have adopted the minimization method of reducing keys. Generally, a drastic key reduction in order to achieve sufficient wearability increases KSPC (Keystrokes per Character), decreases text entry performance, and requires additional effort to learn a new typing method. We are faced with wearability-usability tradeoff problems in designing a good wearable keyboard. To address this problem, we adopted a new keyboard minimization method of reducing key pitch and have developed the One-key Keyboard. The traditional desktop keyboard has one key per character, but One-key Keyboard has only one key (70mmX35mm) on which a 10*5 QWERTY key array is printed. One-key Keyboard detects the position of the fingertip at the time of the keying event and figures out the character entered. We conducted a text entry performance test comprised of 5 sessions. The participants typed 18.9WPM with a 6.7% error rate over all sessions and achieved up to 24.5WPM. From the experiment’s results, the One-key Keyboard was evaluated as a potential text input device for wearable computing, balancing wearability, social acceptance, input speed, and learnability.
The most common user interfaces for a wearable computer that are suggested or commercialized in general are the wrist-worn keyboards such as Halfkeyboard, WristPC keyboard, Frogpad, Stick Keyboard and so on. These input devices attempt to minimize the size by decreasing the number of keys. In order to input texts with only a few keys, multitapping or key combination has to be adopted. It is possible to reduce the number of keys by using multitapping system as Stick Keyboard did. However, the input speed decreases significantly due to the increase of KSPC (keystrokes per character). In case of Halfkeyboard and WristPC keyboard, the input efficiency is rather exceptional, but it is unnatural to wear on the wrist in daily life because of the size. In this research, we focused on suggesting a way to minimize the QWERTY keyboard without increasing KSPC. If this is possible, it can have high qualities of sufficient wearability, input efficiency, and learnability. One way to minimize a keyboard without increasing KSPC is to reduce the key pitch of a desktop QWERTY keyboard instead of reducing the key numbers. If a smaller size of keyboard can be made with reduced the key pitches, wearability will be improved. However, the input error will increase while the input speed decreases because of the thickness of human fingers. Since wearability and text entry performance are in trade-off relationship, it is important to find the optimal balancing point.
Author Keywords
Wearable Computing, Text entry, Keyboard. ACM Classification Keywords
H5.2 [Information Interfaces and Presentation]: User Interfaces –Input devices and strategies
Examples of minimizing QWERTY keyboard by reducing key pitch are Graphic keyboard for PDA and mini-QWERTY keyboard of Targus and Dell. The former uses a stylus to input a key with about 4mm key pitch. The latter inputs the text by holding the keyboard with two hands and pressing the buttons (about 7mm key pitches) with two thumbs. According to the previous research of measuring input efficiency, the input speed of graphic keyboard for PDA was 13.64WPM (only one session) with 4.11% error rate. With mini-QWERTY keyboard, the input speed is 60.03WPM and the error rate is 8.32% after 20 times of 20-minute sessions. Concerning the input speed, mini-QWERTY keyboard shows far better performance than graphic keyboard.
INTRODUCTION
A keyboard in the wearable computing environment should have sufficient wearability, enough fast input speed, and low error rate when users input texts. It should also be easy for general users to learn without any special training, and use marketable technologies. Due to the difference between the wearable computing environment and the desktop computing environment, the requirements mentioned above easily contradict each other, and it is not easy to find a meaningful balancing point. Hence, it is difficult to find an input device which equally satisfies
In this study, we tried to develop a keyboard that can be worn easily on the wrist and can be used with one hand, considering the wearable computing environment where text input device should have sufficient wearability as well as the maximum degree of freedom of hands.
OZCHI 2006, November 20-24, 2006, Sydney, Australia. Copyright the author(s) and CHISIG Additional copies are available at the ACM Digital Library (http://portal.acm.org/dl.cfm) or ordered from the CHISIG secretary ([email protected]) OZCHI 2006 Proceedings ISBN: 1-59593-545-2
305
Moreover, we worked to establish an efficient text input method that does not need any additional instruments such as a stylus due to the active wearable computing environment. WEARABILITY OF MINIMIZED KEYBOARD EXPECTATION OF SOCIAL ACCEPTANCE
AND
Unlike the desktop computing environment, people have to wear a keyboard in wearable computing environment. A keyboard has to not only have good input efficiency but also be worn comfortably and used in daily life without any difficulty. The keyboard size will be a crucial factor in deciding wearability and social acceptance. We conducted an experiment to investigate what effect a keyboard size has on wearability and social acceptance. The sizes of the keyboard model for the test are set into six levels as seen in figure 2 based on the specification of WristPC (148*65*13mm) and Halfkeyboard (145*80*18mm). The width is respectively 50mm, 70mm, 90mm, 110mm, 130mm, 150mm and height is 1/2 of the width. The thickness of prototype is all controlled to 7mm. Each model is worn with the shape attached on wrist band.
Figure 1. Minimized keyboard models for evaluating wearability and social acceptance (From top-left to bottomright, a width of keyboard is 50mm, 70mm, 90mm, 110mm, 130mm, and 150mm.) 7.0
Mean ratings (1~7).
Twelve college students (6 males, 6 females) participated. The average age of participants was 23.8 years: 24.2 for male and 23.3 for female. The experiment conductor randomly selected one of the keyboard models and let the participant put it on and evaluate the “wearability: how comfortable to wear” using 7 point rating scale (1 point: very uncomfortable, 4 point: neutral, 7 point: very comfortable). With the same setting, a participant also evaluated the “social acceptance: is it acceptable to wear it in daily life?” using 7 point rating scale (1 point: very unacceptable, 4 point: neutral, 7 point: very acceptable). Furthermore, we prepared the commercialized WristPC keyboard and Halfkeyboard for a participant to evaluate wearability and social acceptance using the same setting as mentioned above. The results are given in Figure 2.
Wearability Social acceptance
6.0 5.0 4.0 3.0 2.0 1.0 50mm
70mm
90mm 110mm 130mm 150mm
H/K
W/K
Keyboards
!
Figure 2. Experiment results for wearability and social acceptance of minimized keyboard models, Halfkeyboard, and WristPC keyboard. (H/K: Halfkeyboard, W/K: WristPC keyboard)
experiment result, the size of a keyboard should be smaller than 90mm, approximately the size of a name card. We confirmed that 70mm and 50mm keyboards are satisfactory in wearability and social acceptance.
As shown in Figure 2, wearability and social acceptance of WristPC keyboard are rated 3.8/7.0(StDev: 1.2) and 2.6/7.0(StDev: 1.1). Those of Halfkeyboard are rated 3.2/7.0(StDev: 1.2) and 2.1/7.0(StDev: 0.7). WristPC keyboard which is designed as a wrist-worn type shows rather convincing result in wearability, yet considerably low result in social acceptance. In the case of Halfkeyboard, both wearability and social acceptance are rather low.
CONCEPT OF ONE-KEY KEYBOARD
One-key Keyboard literally means text input device which has only one key. In case of traditional keyboard, while one character is assigned to one key, One-key Keyboard displays whole QWERTY keyboard layout of characters in one keyboard. This allows the key space to be reduced dramatically. It is a mechanism to input pertinent characters by sensing the finger’s position on the letter plate and pressing the switch which is whole keyboard.
In the case of the keyboard models that we used in this research, wearability and social acceptance are in inverse proportion to the size. According to within-subject oneway ANOVA test, it is confirmed that the size of the keyboard has a significant effect on wearability (F(5,55)=26.307, p
