Keypad signal input apparatus

• US 20060284741A1
• Filed: 06/30/2004
• Published: 12/21/2006
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Khlat, Nadim
• Granted Patent: US 7,339,499 B2
• Time in Patent Office: Days
• US Class Current: 341/22
• CPC Class Codes: G06F 3/0338 with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: H01H 2221/012 Joy stick type
• CPC Class Codes: H01H 2225/018 Consecutive operations
• CPC Class Codes: H01H 2239/012 Decoding impedances
• CPC Class Codes: H03M 11/22 Static coding H03M11/26 takes precedence
• CPC Class Codes: H03M 11/24 using analogue means , e.g. by coding the states of multiple switches into a single multi-level analogue signal or by indicating the type of a device using the voltage level at a specific tap of a resistive divider

Abstract

Keypad apparatus for registering signals corresponding to data that a user enters by pressure on keys of an array in a surface extending in two dimensions. The elements of first and second sets of impedance elements (R) are connected in series through respective interconnections and a signal processor applies first and second reference signals across the first and second sets of impedance elements respectively. User pressure on the keys makes or breaks connections through corresponding contact elements between a respective pair of the interconnections, one from the first set of impedance elements and one from the second set of impedance elements, so as to generate first and second output signals (PX1, PY1) that together are a corresponding combination of the first and second reference signals that is unique to the actuated key elements.

Claims

1. Keypad apparatus for registering signals corresponding to data that a user enters by pressure, comprising:

a surface extending in two dimensions;

first and second sets of impedance elements, the elements of each set being connected in series through respective interconnections;

reference signal means for applying first and second reference signals across said first and second sets of impedance elements respectively; and

an array of discrete key elements juxtaposed with said surface and selectively actuable by user pressure on said features to make or break connections through corresponding contact elements between a respective pair of said interconnections, one from said first set of impedance elements and one from said second set of impedance elements, characterised by said reference signal means is arranged to apply said reference signals alternately across said first set and across said second set of impedance elements, so as to generate first and second output signals that together are a corresponding combination of said first and second reference signals that is unique to the actuated key elements, and output means responsive to said output signals, said output means comprising digital-to-analogue converter means common to said first and second output signals.

2. Keypad apparatus as claimed in claim 1, wherein said reference signals are respective direct voltages and said impedance elements present electrical resistances.

3. Keypad apparatus as claimed in claim 1 or 3, wherein said array of discrete key elements comprises a two-dimensional array of switches disposed at said surface for actuation by the user and connected with respective pairs of said interconnections.

4. Keypad apparatus as claimed in claim 3, wherein said array of discrete key elements is an orthogonal array.

5. Keypad apparatus as claimed in claim 3, and comprising;

a third set of said impedance elements connected in series through respective interconnections, said reference signal means being arranged to apply third reference signals across said third set of impedance elements, at least some of said key elements comprising a three-dimensional disposition of said electrical contact elements said features being progressively movable transversely to said surface by user pressure to make or break connections through corresponding contact elements between an interconnection from said first set of impedance elements, an interconnection from said second set of impedance elements and also a respective interconnection from said third set of impedance elements selected by the degree of user actuated movement of the key, so as to generate first, second and third output signals that together are a corresponding combination of said first, second and third reference signals that is unique to the actuated contact elements.

6. Keypad apparatus as claimed in any preceding claim 5 wherein simultaneous actuation of adjacent ones of said discrete key elements is arranged to generate first and second output signals that are a corresponding combination of said first and second reference signals unique to the simultaneously actuated key elements.

7. Keypad apparatus as claimed in claim 5, wherein said output means includes analogue to digital converter means responsive to analogue values of said output signals to generate digital output signals.

8. Keypad apparatus as claimed in claim 5, wherein said reference signal means is arranged to apply said reference signals alternately across said first set and across said second set of impedance elements, so as to generate said first and second output signals alternately.

9. Keypad apparatus as claimed in claim 8, wherein said reference signal means is responsive to actuation of a discrete key element to trigger application of said reference signals alternately across said first and second sets of impedance elements.

10. Keypad apparatus as claimed in claim 9, wherein said reference signal means is responsive to actuation of a discrete key element to generate a trigger signal, said reference signal means including signal processing means responsive to said trigger signal for processing said output signals.

11. Keypad apparatus as claimed in claim 9, wherein said first and second sets of impedance elements are connected between first and second pairs of terminals respectively, said reference signal means is arranged to apply said reference signals alternately across said first and second pairs of terminals, and said output means is responsive to said output signals appearing at least one of said terminals to which said reference signals are not being applied.

12. Data entry apparatus comprising keypad apparatus as claimed in claim 5 and further comprising a touch panel apparatus comprising first and second juxtaposed impedance layers presenting distributed impedances, first and second pairs of electrodes coupled with respective pairs of opposed edges of said impedance layers, and connection means for selectively operably connecting said reference signal means and said output means with said sets of impedance elements of said keypad apparatus or with said pairs of electrodes of said touch panel apparatus.