Basic Principle. These trapped energy regions are set into motion with transducers and act as high quality resonators.

Transcription

1 Switches

2 Basic Principle Material capable of supporting shear and torsional mechanical waves at ultrasonic frequencies can have those waves trapped or localized by contouring its surface.

3 Basic Principle These trapped energy regions are set into motion with transducers and act as high quality resonators.

4 Basic Principle When a resonator is set into vibration in the MHz range by a properly positioned ultrasonic transducer, a wave motion is induced.

5 Basic Principle The motion is confined to the shape of the Resonant Cavity, and it extends through the thickness of the metal.

6 Basic Principle This creates a natural resident decay curve of the specific material used, This curve is mapped by the electronics for the inactivated state.

7 Basic Principle When a finger touches the surface, energy is absorbed The resonant properties of the material have changed.

8 Basic Principle The electronics see this change, so a touch is detected.

9 Going Further When the surface of a switch plate is contoured as depicted here, it creates raised regions or Resonant Cavities

10 Going Further Not just a single button solution but the possibility for Keypads, Keyboards and data interfaces.

11 How does it work? Active Touch excites and monitors sonic mechanical vibrations in solid material. Transducer excites localised wave in material Transducer monitors resonating wave decay Absorbing material, finger dampens the wave Switch circuitry detects wave interruption, signals switch actuation Note: any damping wave is detected basis for range of sensors

12 What makes an Active Touch switch? Resonant Cavity: Machined detail that traps energy to a defined space. Boundaries are set by changes in acoustic properties, e.g. thickness of material, surface finish, and applied materials. (appliqué) Surface: Machined, bare, anodized, painted, labelled, covered with bonded or un-bonded membrane. Material thickness: mm, Size: 3 40mm, diameter Spacing: >4mm,.160 c-c

13 What makes an Active Touch switch? Transducer: Small ceramic crystal, PZT One transducer per switch position Mechanically bonded to back of resonant cavity Electrically connected to control circuit

14 What makes an Active Touch switch? Switch Circuitry: Microcontroller Drives transducer MHz range oscillations Monitors transducer- counts resonant vibrations Compares count to natural decay Reports damping as switch actuation Multiplexing: 1 microcontroller with multiplexer can run 16 switches

15 Feature/Function/Benefits: Mechanical NO moving/flexing/wearing parts: extreme life Environmental limits set by materials/construction Temp: -40 to +80 C RH: 0% submerged Sealed: positive sealing from particulates, water, gases, sterilisation solutions Unaffected by mechanical vibration/impact: useful in high vibration applications Switch ruggedness limited by protection/isolation of circuitry and transducer Flexible geometry: wide range of configurations, unique switch functions

16 Feature/Function/Benefits: Mechanical Outputs data: No bounce, input fed to control system Switch control can be integrated with device controller Switch operation unsusceptible to RFI/EMI* Generates/radiates NO RFI/EMI* Software-adjustable actuation force, duration: very low force for repetitive motion uses, long duration for permissive switches Multiple/variable actuation forces may be detected Any absorber works: Unaffected by gloves/overlay Switch state/operation can be verified in real time Inherently explosion proof: no special construction required *With adequate control circuit protection

17 Competitive Analysis Piezoelectric switches: Requires PZT crystal deflection, switch structure must flex: limits life, actuation force ranges, structural integrity Held switch actuation undetectable Output voltage varies with push dynamics; may require signal conditioning Requires enclosure penetrations Tact/dome switch: Limited life: contacts/return mechanism Bounce/Voltage characteristics Actuation pressure/duration modifiable

18 Possible Configurations Single Pushbutton: Ganged as keypad, keyboard Resonant cavities and switch control may be integrated into other components Switches moulded into complex shapes, e.g. tool handle, joystick, other handheld device Bar or tube contact sensor

19 Customer Applications to date Kiosks Keyboards Aircraft primary flight instrument LCD bezel Machine control pushbuttons

20 Current Development Projects Spa controls i-pod style, modular switches Pushbar Passenger presence detection Switches/Keypads for security applications Self-diagnostics for avionics bezel switches Touch sensitive faucet controls Personal under water propulsion sled controls Sensing for food processing equipment

21 Potential Applications Medical: Clean rooms Operation Equipment ESD safe switching Fluid detection Appliance: Linear/rotary controls Level controls Handle sensors

22 Thank you from