3m Innovative Properties Company

New Transducers Limited

Nicholas P R Hill

Darius M Sullivan

A touch sensing device includes a plurality of sensors and an emitting transducer coupled to a touch panel. The transducer induces bending waves in the touch panel. The sensors sense bending waves in the touch panel and generate a bending wave signal responsive to the sensed bending waves. A controller identifies an untouched condition signal responsive to the induced bending waves. The controller compares the untouched condition signal to the bending wave signal, and detects a touch on the touch panel based on the comparison.

Touch sensing with touch down and lift off sensitivity

The present invention provides a touch sensitive input device that uses vibrations due to touch impacts and/or frictional movement of a touch implement across a surface to determine information related to the touch, such as touch position. The present invention also provides for detecting lift-off events in such vibration sensing input devices. Lift-off detection can be accomplished by monitoring for a signal that indicates a sustained touch on the touch plate, and correlating a change in such a signal with a lift-off event. Signals indicating a sustained touch can include low frequency rumbles coupled into the touch plate via the touch implement, touch plate bending under the force of a sustained touch, and touch plate displacement under the force of a sustained touch.

Vibration sensing touch input device

A touch sensitive apparatus includes a touch plate to which several pickup sensors and at least one excitation transducer are coupled. Each of the sensors is configured to sense bending waves in the touch plate, and the excitation transducer is configured to induce bending waves in the touch plate. The apparatus may further include active buffer circuits, wherein each of the active buffer circuits is coupled to one of the sensors. A controller is coupled to the sensors via the active buffer circuits and to the excitation transducer via a non-actively buffered connection. The controller is configured to compute a location of a contact on the touch plate responsive to sense signals received from the sensors. The apparatus may be used to perform a variety of calibrations, including touch plate and sensor calibrations. Changes in touch sensing apparatus calibration and performance may be detected and tracked over time.

Touch sensitive device employing bending wave vibration sensing and excitation transducers

The present invention provides a piezoelectric transducer that includes at least two poled piezoelectric regions disposed in a side-by-side arrangement and connected in series with the poling directions reversed through the series connection, meaning that the 'north pole' of one region is connected to the 'south pole' of an adjacent region. The at least two regions can be within the same piece of piezoelectric material, or can be separate pieces of piezoelectric material. Transducers of the present invention may be particularly suited to detecting vibrations such as bending waves in a plate. For example, transducers of the present invention may be affixed to a surface of a plate and used to detect vibrations caused by or affected by touches to the plate to determine information related to the touches, such a touch position.

Piezoelectric transducer

A touch sensitive apparatus includes a touch plate and a number of sensors coupled to the touch plate. Each of the sensors is configured to sense bending waves in the touch plate and, in response to a touch to the touch plate, generate sensor signals. A controller is coupled to the sensors. The controller corrects for dispersion in the sensor signals and determines a location of the touch using the dispersion corrected signals. The controller performs impulse reconstruction, by which impulses representative of impulses generated by the touch to the touch sensitive device are produced. Using the reconstructed impulses, the controller confirms the location of the touch.

Touch sensitive device employing impulse reconstruction

Method and apparatus using bending wave vibration to calculate information relating to a contact on a contact sensitive device. The contact sensitive device has a member capable of supporting bending waves, and a device attached to the member measures bending wave propagation in the member to determine a measured bending wave signal. The measured bending wave signal is processed to calculate information relating to the contact. The contact sensitive device may comprise a transparent touch sensitive plate mounted in front of a display device. A stylus (e.g., pen) may be used for writing text or other matter on the touch-sensitive plate. The plate may also be an acoustic device. Three transducers are mounted on the plate. At least two of the transducers are sensing transducers and are thus sensitive to and monitor bending wave vibration in the plate.

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Cambridge, United Kingdom

Nicholas P R Hill