Minako Hashimoto and Masatomo Togasi
This paper proposes a virtual oval keyboard whose shape is designed on the basis of the easily pointed area with a pen, and a vector input method where user can input both a vector and its origin with one wedge-shaped stroke. Since the shape of conventional virtual keyboards, a rectangle, is not suitable for rotational movement of a wrist, it forces much strain upon the wrist. And since non-alphabet keys frequently used in typing English texts, such as space, are assigned on the outside of alphabet key area on the conventional virtual keyboards, it is necessary to move the wrist excessively. The virtual oval keyboard fits a natural movement of a wrist, because a reclined oval is obtained as the easily pointed area by our experiment. In our preliminary experiment for evaluation, all subjects input faster with the virtual oval keyboard than with a conventional virtual keyboard. In the vector input method, four kinds of vectors enable users to input space, carriage return, back space and SHIFT at any position without moving a pen out of the alphabet key area.
Most of pen-based interfaces enable users to input characters
with handwriting. But the users do not always prefer to handwriting
because it is too constrained and demands much attention[1].
Therefore a virtual keyboard(VKB) is needed in place of handwriting.
There are three problems with a conventional VKB.
First, its rectangular shape is not suitable for a natural movement
of a wrist; it forces much strain upon the wrist.
Secondly, it is necessary to move a wrist excessively,
because the non-alphabet keys which are used frequently in typing
English texts, such as space, are assigned on the outside of
alphabet key area.
Finally, because it is impossible to point two keys with a pen at a time,
it needs an additional stroke to do SHIFT operation.
We design a virtual oval keyboard(VOKB) and propose a vector input
method for pen-based character input.
VOKB enables a natural movement of a wrist and solves
the first problem given above. Non rectangular shape of the VOKB
is obtained by our experiment mentioned in the following section.
The results of our preliminary experiment indicated that
all subjects input faster with our VOKB than with a conventional VKB.
The vector input method enables users to input both a vector and
its origin with one wedge-shaped stroke and solves the second and
third problems given above. In this method, four kinds of vectors
correspond to space (SP), carriage return(C/R),
back space(BS) and SHIFT which are assigned
on the outside of alphabet key area on conventional virtual keyboards.
VOKB is designed on the basis of an easily pointed area with a pen.
The area is obtained by the following experiment.
Subjects
Thirteen right-handed women in their twenties.
Equipment
A personal computer (Gateway 2000) with a tablet (WACOM PL-100VA)
and a stylus pen.
Design and procedure
The tablet was mounted at a 30 degree angle from horizontal.
The window for the experiment having 95mm width and 95mm height
appeared on a center of the tablet.
Each subject sat down in front of the tablet and fixed her little
finger in the right bottom corner of the window.
The subject kept to point freely with a pen for 4 minutes.
This operation was repeated twice.
Results
The results are shown in Figure 1.
The square represents the window used for the experiment, and the
density of black points represents the frequency of the pointing
on the position. As the figure indicates, the frequently pointed area
forms a reclined oval. We conclude that it is easier to point within
the reclined oval than within the rectangle.
We determined a reclined oval (Figure 2) as the shape of VOKB
on the basis of the results(Fig.1).
Then we assigned keys according to QWERTY keyboard arrangements.
Our VOKB is shown in Fig.3.
We reserve the upper region for later expansion such as function keys.
Fig.3:The virtual oval keyboard
We compared our VOKB with a conventional VKB about input speed
by the following preliminary experiment.
Seven right-handed women in their twenties participated as novices
in this experiment. Each subject was to tap the key with a pen
in direct response to whatever key was illuminated.
As soon as the key was pointed, a next key was illuminated
according to frequencies of English alphabet digraphs[3].
It was repeated continuously 1000 times.
All subjects input faster with our VOKB than with a conventional VKB.
Table.1 shows mean time(MT) and its standard deviation(SD) to input
one character.
Table.1: MT and its SD to input one character.
A vector input method enables users to input both a vector and
its origin with one wedge-shaped stroke. Since the vector is recognized
only from the relation between its origin and its end, a complicated
algorithm, as in case with handwriting and gesture recognition[2],
is not needed.
The vector input method solves two problems on the conventional
pointing input method mentioned in Introduction.
First, three kinds of vectors correspond to SP, C/R and BS
which are used frequently in typing English texts.
These vectors can be started at any position on the VOKB
and it comes to be possible to input without moving a pen out of
the alphabet key area.
Next, one vector is used for SHIFT.
In this case, a letter on the origin of a vector is shifted
with just one wedge-shaped stroke.
Four kinds of vectors are presented in Figure 4.
These are implemented on our VOKB.
Figure 4: Parameters of four kinds of vectors X
Each vector is characterized by combination of its length, long or short,
and its direction, right or left. Because a standard of length is
different in each user,Rs,RL can be set freely as one likes.
We presented a virtual oval keyboard(VOKB) which was designed within
an easily pointed area with a pen and enabled a natural movement of a wrist.
In our preliminary experiment for evaluation,
all subjects input faster with VOKB than with the conventional one.
And we proposed a vector input method which enabled users to input
both a vector and its origin with one wedge-shaped stroke for pen-based
character input.
We plan to evaluate VOKB and a vector input method with respect to
input speed and error rate.
We also plan to apply VOKB with a vector input method
to other languages such as Japanese.
Thanks are due to WACOM Co.Ltd. for lending us a tablet.
We also thank the subjects for participating our experiment,
and Masataka Goto for his helpful comments on earlier drafts of this paper.
Introduction
A VIRTUAL OVAL KEYBOARD
Experiment
Design
PRELIMINARY EXPERIMENT FOR EVALUATION
Experiment
Results
A VECTOR INPUT METHOD
CONCLUDING REMARKS
ACKNOWLEDGEMENT
