Piezo electric keypad assembly with tactile feedback

• US 20020084721A1
• Filed: 01/03/2001
• Published: 07/04/2002
• Est. Priority Date: 01/03/2001
• Status: Abandoned Application

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Walczak, Thomas J.
• Application Number:
  US09/753,811
• Publication Number:
  US 20020084721A1
• Time in Patent Office: Days
• US Class Current: 310/339
• CPC Class Codes: H03K 17/9643 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/96062 with tactile or haptic feedback
• CPC Class Codes: H04M 1/23 Construction or mounting of dials or of equivalent devices; Means for facilitating the use thereof by improving visibility H04M1/22
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00

Abstract

This invention is a keypad assembly (100) for a portable communication device having a plurality of piezoelectric keys (110) to receive user input and providing tactile feedback to the user in response to such user input. The keypad assembly (100) includes one or more keys in which each key (110) has a piezoelectric layer (210), a conductive layer (220) on one side of the piezoelectric layer and another conductive layer (230) on the other side of the piezoelectric layer. The keypad assembly (100) also includes an electronic circuit (120) coupled to the conductive layers (220, 230) of each key (110). When the electronic circuit (120) receives a selection signal from a particular key (110) of the keypad assembly (100), the electronic circuit provides a feedback signal to the particular key in response.

Claims

1. A keypad assembly for a portable communication device comprising:

at least one key having a piezoelectric layer, a first conductive layer on one side of said piezoelectric layer and a second conductive layer on another side of said piezoelectric layer; and

an electronic circuit coupled to said first and second conductive layers of said at least one key, said electronic circuit being effective to provide a stimulus signal to said at least one key in response to receiving a selection signal from said at least one key.

2. The keypad assembly of claim 1, wherein said first conductive layer includes a plurality of conductive pads individually connected to said electronic circuit.

3. The keypad assembly of claim 1, wherein said second conductive layer includes a plurality of conductive pads interconnected to each other and collectively connected to said electronic circuit.

4. The keypad assembly of claim 1, further comprising a membrane layer on a side of said first conductive layer opposite said piezoelectric layer.

5. The keypad assembly of claim 1, wherein said at least one key includes a plurality of keys and said electronic circuit provides a different stimulus signal to each of said plurality of keys.

6. The keypad assembly of claim 1, wherein said electronic circuit includes a comparator to produce a response signal after comparing said selection signal to a reference signal and determining that a particular key said at least one key has been activated.

7. The keypad assembly of claim 6, wherein said electronic circuit includes a driver to send said stimulus signal to said particular key after said comparator has determined that said particular key has been activated.

8. The keypad assembly of claim 7, wherein said electronic circuit includes a processor capable of sending a feedback signal and an activation signal to said driver, said driver being effective to forward said feedback signal to said particular key in response to receiving said activation signal.

9. The keypad assembly of claim 1, wherein said electronic circuit detects a current pulse from a mechanical deformation of said at least one key.

10. The keypad assembly of claim 1, wherein said electronic circuit provides a current pulse to said at least one key to cause a mechanical deformation of said at least one key.

11. The keypad assembly of claim 1, wherein said electronic circuit includes first and second transistors, said first transistor having a collector being effective to drive a base of said second transistor.

12. The keypad assembly of claim 11, wherein said electronic circuit includes a capacitor positioned between said at least one key and a collector of said second transistor, said capacitor being effective to control current flow to said at least one key.

13. The keypad assembly of claim 1, wherein said electronic circuit includes an operational amplifier and a diode connected in series with said operational amplifier.

14. The keypad assembly of claim 13, wherein said electronic circuit includes a capacitor positioned between said operational amplifier and said diode, said capacitor being effective to control current flow from said diode to said at least one key.