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In this paper, we propose Predictive Zooming Keyboard (PZBoard) which predicts a target position from the finger movement above the touch-screen of a mobile device and that enlarges a part of the keyboard around the predicted position. We use a hover function of the mobile device to obtain the finger position above the touch-screen. While a finger is detected, a part of the keyboard around the finger position are enlarged. When the user moves his/her finger fast to enter a distant key, the target position is predicted and the center of enlargement moves to the predicted position. Using prediction, the system can start drawing the screen before the finger reaches the target position, which reduces the system's latency and quickens the user's response. The proposed interface does not force the user to perform additional operation for enlarging keys, and enables stable selection of both near and distant keys by fixing or changing the center of enlargement based on the velocity of the finger.

In this paper, we propose a system which uses two cameras in combination with a touch panel. The cameras detect a continuous finger depth, which realizes zooming in/out the screen together with the finger movement. The system realizes comfortable selection operation of small objects by directly touching enlarged objects. We conducted an experiment and confirmed the effectiveness of the proposed method with zooming. In the virtual keyboard application, the number of mistypes with the proposed method was less than half of the number without zooming.