Touch Sensitive Device

Abstract

An apparatus including a touch sensitive screen having a face adapted to receive a user's hand-writing via a hand-held stylus. The screen includes means exciting the screen to vibrate so as to transmit the vibration to the stylus to simulate the sensation of a writing implement writing on paper as the stylus is moved over the face of the screen. The apparatus may include means for period modulating the electrical signal applied to the exciting means and means for amplitude modulating the electrical signal. The apparatus may include means for sensing the velocity of movement of the stylus over the screen face and means for modulating the vibration according to the sensed velocity.

Description

TECHNICAL FIELD[0001]The invention relates to touch sensitive devices including touch sensitive screens or panels, in particular panels for use with a stylus or other writing instrument.BACKGROUND ART[0002]U.S. Pat. No. 4,885,565, U.S. Pat. No. 5,638,060, U.S. Pat. No. 5,977,867, US2002 / 0075135 describe touch-operated apparatus having tactile feedback for a user when touched. In U.S. Pat. No. 4,885,565 an actuator is provided for imparting motion to the CRT when the actuator is energised to provide tactile feedback. In U.S. Pat. No. 5,638,060, a voltage is applied to a piezo-electric element which form a switch to vibrate the element to apply a reaction force to a user's finger. In U.S. Pat. No. 5,977,867, a tactile feedback unit generates a mechanical vibration sensed by the user when the touch screen is touched with a finger or a pointer. The amplitude, vibration frequency and pulse length of the mechanical vibration are controlled, with the pulse width being long enough to be fel...

AI Technical Summary

Benefits of technology

[0005]Paper comprises a fibre mat in a binder with individual fibres having a random orientation resulting in a rough surface having local variations in the coefficient of friction (sliding or static) on the level traced by the small contact patch between the tip of a pencil and the paper surface. The motion of a pencil over the surface may be described as stick-slip style motion. A similar effect is felt when writing with other writing instruments, such fibre tip pen. For other types of writing instruments, variations on the effect may be felt. For example for a fountain pen this may be scratchy if a bad nib but have a smoothish, water lubricated glide if good. The type of paper also has an effect and often fountain pen users are selective about finding paper with the right nib feel and which takes ink at the right rate without bleeding. For biros, there is a viscous smooth friction sliding but the paper does have some underlying fibrous texture.

[0006]In contrast, when writing with a stylus or pointer on a polymer or glass cover of a touch sensitive panel or surface, this slip-stick motion is lost. The slip stick behaviour of pencil on paper is a key element of the writing sensation. Writing to touch sensitive screens with a stylus has improved sensation, appeal and user satisfaction when there is a simulation of the pencil on paper writing characteristic.

[0020]The signal generating means may further comprise a filter to reduce high-frequency content. In this way, a realistic feel may be provided with as little noise as possible.

Problems solved by technology

In contrast, when writing with a stylus or pointer on a polymer or glass cover of a touch sensitive panel or surface, this slip-stick motion is lost.

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