Miniature isometric joystick

• US 5,889,507 A
• Filed: 07/24/1996
• Issued: 03/30/1999
• Est. Priority Date: 07/24/1990
• Status: Expired due to Fees

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Incontrol Solutions, Inc.
• Inventors: Engle, T. Scott, Franz, Patrick J.
• Primary Examiner(s): NGUYEN, CHANH DUY
• Application Number:
  US08/685,486
• Time in Patent Office: 979 Days
• Field of Search: 345/156, 345/157, 345/160, 345/161, 345/168, 345/184, 200/5 A, 200/6 A, 200/511, 200/513, 200/333, 200/302.2, 200/341-345, 200/517, 200/521, 200/522, 338/99, 338/114, 338/128, 74/471 XY, 74/553, 341/20, 341/22, 341/27, 341/34, 318/640, 400/490, 400/491, 400/491.3, 400/495
• US Class Current: 345/161
• CPC Class Codes: G05G 2009/04762 Force transducer, e.g. strain gauge
• CPC Class Codes: G05G 9/047 the controlling member being movable by hand about orthogonal axes, e.g. joysticks for switches H01H25/04
• CPC Class Codes: G06F 3/0213 Arrangements providing an integrated pointing device in a keyboard, e.g. trackball, mini-joystick for pointing devices integrated in a laptop computer G06F1/169; joysticks G05G9/047; constructional details of pointing devices G06F3/033
• CPC Class Codes: G06F 3/023 Arrangements for converting discrete items of information into a coded form, e.g. arrangements for interpreting keyboard generated codes as alphanumeric codes, operand codes or instruction codes
• 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: H01H 13/70 having a plurality of operating members associated with different sets of contacts, e.g. keyboard mounting together a plurality of independent switches H02B
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 13/807 characterised by the spatial arrangement of the contact sites, e.g. superimposed sites
• CPC Class Codes: H01H 2003/0293 with an integrated touch switch
• CPC Class Codes: H01H 2201/02 Piezo element
• CPC Class Codes: H01H 2201/036 Variable resistance
• CPC Class Codes: H01H 2221/012 Joy stick type
• CPC Class Codes: H01H 2225/018 Consecutive operations
• CPC Class Codes: H01H 2225/03 Different type of switches
• CPC Class Codes: H01H 2239/006 Containing a capacitive switch or usable as such
• CPC Class Codes: H01H 2239/052 Strain gauge
• CPC Class Codes: Y10T 74/20201 Control moves in two planes

Abstract

A miniature isometric joystick is disclosed for receiving manual user input to effect directional control such as controlling cursor movement on a computer display screen or controlling movement of an apparatus such as a machine or robot. The joystick is arranged to fit between the existing keys in a computer keyboard. The joystick includes a preloading spring for compressing the assembly together, thereby biasing the force sensors so as to neutralize manufacturing variations and control electrical and mechanical null zones. An integrated switch is provided in the joystick for detecting an external force applied by the user'"'"'s fingertip. The switch unobtrusively detects when a user is pointing, thereby allowing a control system to measure pointing system bias signals while the user is not pointing. This permits the control system to automatically correct for drift, without requiring additional keyboard space for a separate switch to enable the pointing device.

Claims

1. A low-travel switching joystick apparatus comprising:

a rigid shaft;

a pliable, hollow cap covering a top end of the shaft, the cap having an electrically conductive interior surface, and being coupled to the shaft along a peripheral edge of the cap;

an electrically conductive interior electrode overlying a central portion of the top end of the shaft and spaced apart from the said interior surface of the cap so as to permit generally downward deformation of the cap for establishing contact between the said interior surface and the interior electrode in response to pressure applied to the cap by the user'"'"'s finger; and

integrated switch means coupled to the interior electrode for detecting presence of the user'"'"'s fingertip contacting the cap, the interior electrode having a depending portion extending through the shaft for electrical connection of the switch means.

2. The joystick apparatus according to claim 1 further including a ledge formed along a periphery of the shaft upon which the peripheral edge of the cap is seated.

3. In a computer keyboard having a baseplate and an array of existing keyswitches mounted on the baseplate, a method of acquiring electrical signals responsive to forces applied by a user for controlling cursor movement on a visual display screen, the method comprising:

selecting a location on the baseplate intermediate the existing keyswitches;

providing a plurality of force sensing elements, each such element having an electrical characteristic that varies in response to force applied to said element;

symmetrically arranging the force sensing elements around the selected location, so that the force sensing elements do not interfere with operation of the existing keyswitches;

providing an actuator assembly positioned on top of the force sensing elements and supported solely by the force sensing elements, the actuator assembly having a shaft extending upward from the selected location in between the existing keyswitches for operation by the user'"'"'s fingertip;

maintaining a pre-loading force on the actuator assembly generally along a vertical axis normal to the baseplate so as to force the actuator assembly against all of the force sensing elements in the absence of an external force on the shaft, whereby any force applied to the shaft by the user'"'"'s fingertip produces a responsive change in the electrical characteristic of at least one of the force sensing elements without overcoming a null zone of operation;

providing an integrated switch coupled to the shaft for detecting a force applied by the user'"'"'s fingertip contacting the shaft; and

selecting the pre-loading force so as to bias the force sensing elements to a desired intermediate operating point, so that an external deflecting force applied to the shaft angularly offset from the Z axis increases the force on at least one of the force sensing elements and decreases the force on an opposing element, thereby providing differential electrical signals for cursor control in response to said deflection force.

4. A method according to claim 3 further comprising the steps of:

coupling the integrated switch coupled to a top end of the shaft for detecting presence of the user'"'"'s fingertip contacting the top end;

while the user'"'"'s fingertip is not detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring bias force information;

while presence of the user'"'"'s fingertip is detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring pointing force information; and

combining the bias force information and the pointing force information to form directional data for controlling cursor movement on the visual display screen.

5. In a computer keyboard having a baseplate and an array of existing keyswitches mounted on the baseplate, a method of acquiring electrical signals responsive to forces applied by a user for controlling cursor movement on a visual display screen, the method comprising:

selecting a location on the baseplate intermediate the existing keyswitches;

providing a plurality of force sensing elements, each such element having an electrical characteristic that varies in response to force applied to said element;

symmetrically arranging the force sensing elements around the selected location, so that the force sensing elements do not interfere with operation of the existing keyswitches;

providing an actuator assembly positioned on top of the force sensing elements and supported solely by the force sensing elements, the actuator assembly having a shaft extending upward from the selected location in between the existing keyswitches for operation by the user'"'"'s fingertip;

maintaining a pre-loading force on the actuator assembly generally along a vertical axis normal to the baseplate so as to force the actuator assembly against all of the force sensing elements in the absence of an external force on the shaft, whereby any force applied to the shaft by the user'"'"'s fingertip produces a responsive change in the electrical characteristic of at least one of the force sensing elements without overcoming a null zone of operation;

providing an integrated switch coupled to the shaft for detecting a force applied by the user'"'"'s fingertip contacting the shaft;

coupling the integrated switch coupled to a top end of the shaft for detecting presence of the user'"'"'s fingertip contacting the top end;

while the user'"'"'s fingertip is not detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring bias force information;

while presence of the user'"'"'s fingertip is detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring pointing force information; and

combining the bias force information and the pointing force information to form directional data for controlling cursor movement on the visual display screen.

6. A method of acquiring electrical signals responsive to forces applied by a user for controlling cursor movement on a visual display screen, the method comprising:

providing a plurality of force sensing elements, each such element having an electrical characteristic that varies in response to force applied to said element;

symmetrically arranging the force sensing elements around a selected location;

providing an actuator assembly positioned on top of the force sensing elements and supported solely by the force sensing elements, the actuator assembly having a shaft extending orthogonally from the selected location for operation by the user'"'"'s fingertip;

maintaining a pre-loading force on the actuator assembly generally along a vertical axis normal to the force sensing elements so as to force the actuator assembly against all of the force sensing elements in the absence of an external force on the shaft;

providing an integrated switch coupled to a top end of the shaft for detecting a force applied by the user'"'"'s fingertip contacting the shaft; and

sizing and arranging the shaft relative to the existing keyswitches so that the shaft is substantially inaccessible to the user except through the top end, thereby substantially preventing the user from applying force to the actuator assembly without actuating the integrated switch.

7. A method according to claim 6 further comprising the step of selecting the preloading force so as to bias the force sensing elements to a desired intermediate operating point, so that an external deflecting force applied to the shaft angularly offset from the Z axis increases the force on at least one of the force sensing elements and decreases the force on an opposing element, thereby providing differential electrical signals for cursor control in response to said deflection force.

8. A method according to claim 7 further comprising the steps of:

while the user'"'"'s fingertip is not detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring bias force information;

while presence of the user'"'"'s fingertip is detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring pointing force information; and

combining the bias force information and the pointing force information to form directional data for controlling cursor movement on the visual display screen.