Miniature isometric joystick

A joystick comprising:

• a generally flat, rigid reference plate;
• generally planar force sensing means, disposed in parallel contact on top of the reference plate and having a plurality of force sensing elements positioned in a predetermined pattern, for sensing force applied to the sensing elements;
• and
• actuator means disposed on top of the force sensing means and having a plurality of actuator surfaces protruding toward the force sensing means, each of the actuator surfaces contacting a respective one of the force sensing elements for supporting the actuator means and for transmitting to the corresponding force sensing element an external force applied to the actuator means by a user;
• the actuator means being supported solely by the force sensing elements so that substantially all forces applied by the user to the actuator means are transmitted to the force sensing means;
• means for pre-loading the force sensing elements so that each force sensing element provides a respective predetermined output signal when no external force is being applied to the actuator means by the user;
• and
• switch means coupled to the actuator means so as to detect presence of a user's fingertip contacting the actuator means.

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;
• 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.

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 force sensing elements in the absence of an external force on the shaft;
• providing an integrated switch having a tip for activating the switch and coupled to a top end of the shaft for detecting presence of the user's fingertip contacting the shaft;
• substantially covering the top end of the shaft with the tip;
• and
• sizing and arranging the shaft relative to the existing keyswitches so that the shaft is substantially inaccessible to the user except through the tip, thereby ensuring that the user activates the integrated switch whenever the user applies force to the actuator assembly;
• 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.

A miniature isometric joystick apparatus comprising:

• a generally flat, rigid base plate;
• generally planar force-sensing means disposed in substantially parallel contact with the base plate;
• an actuator assembly registered over the force-sensing means for transmitting forces applied to the actuator assembly by a user to the force-sensing means;
• preload means for urging the actuator assembly and the base plate together so as to maintain the actuator plate in constant contact with the force-sensing means so that the force-sensing means is responsive to an initial force applied to the actuator assembly, thereby eliminating a null zone of operation;
• and
• integrated switch means coupled to the actuator assembly for detecting presence of the user's fingertip contacting the actuator assembly;
• wherein a top region of the actuator assembly is sized so as to fit between adjacent keycaps of a standard keyboard so as to permit use of the joystick apparatus without contacting the adjacent keycaps;
• and
• measurement means coupled to the force sensors and coupled to the integrated switch means for acquiring pointing force information while the integrated switch means detects presence of the user's fingertip contacting the actuator assembly and for acquiring bias force information while the integrated switch means does not detect presence of the user's fingertip contacting the actuator assembly.

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;
• providing an integrated switch having a tip for activating the switch and coupled to a top end of the shaft for detecting presence of the user's fingertip contacting the shaft;
• substantially covering the top end of the shaft with the tip;
• and
• sizing and arranging the shaft relative to the existing keyswitches so that the shaft is substantially inaccessible to the user except through the tip, thereby ensuring that the user activates the integrated switch whenever the user applies force to the actuator assembly;
• while the user's fingertip is not detected, measuring the force sensing elements to acquire 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.