Dental device with load-responsive motor control

Abstract

A motor-driven dental device has a motor control that is responsive to a load placed upon the motor. More specifically, the invention relates to a dental device having motor that drives a tool, wherein the tool is activated or otherwise controlled in response to a load placed upon the motor through the tool, such as by touching the tool to a surface. The tool may also be controlled by the sustenance, over a predetermined time period, of an increase or decrease in motor current beyond a predetermined hysteresis current threshold. The motor may be an electric motor, a rotary electric motor, and air driven motor, an ultrasonic device or the like.

1 . A motor driven dental handpiece having a motor control for driving a motor comprising:
 an electric motor;   a tool engagably connected to said electric motor,   an outer sheath; and   an inner module wholly or partially covered by the outer sheath and detachably engaging with said tool;   wherein the handpiece is constructed such that a load applied to the electric motor corresponds to a controlled output goal of the tool,   wherein a controlled output of the motor increases or decreases to said controlled output goal in response to said load,   wherein said load is an increasing or a decreasing load, and   wherein the controlled output is increased for an increasing load and decreased for a decreasing load.   
     
     
         2 . The handpiece according to  claim 1 ,
 wherein the controlled output is a speed of the tool and the load is a torque applied to the electric motor.   
     
     
         3 . The handpiece according to  claim 1 ,
 wherein the handpiece is electrically or pneumatically powered.   
     
     
         4 . The handpiece according to  claim 1 ,
 wherein the handpiece is rotary, reciprocating or oscillating.   
     
     
         5 . The handpiece according to  claim 2 ,
 wherein the speed varies in steps or continuously or proportionally to the torque.   
     
     
         6 . The handpiece according to  claim 1 ,
 wherein the handpiece is waterproof.   
     
     
         7 . A method of controlling a motor driven dental handpiece having a motor control for driving a motor for dental treatment comprising:
 applying a tool of the handpiece to a tooth to generate a load,   applying said load to an electric motor of the handpiece,   increasing or decreasing a controlled output of the tool of the handpiece to a controlled output goal corresponding to said load,   wherein the increasing or decreasing is according to a motor-control profile of the handpiece, and   wherein the controlled output is increased for an increasing load and decreased for a decreasing load.   
     
     
         8 . The method according to  claim 7 ,
 wherein the controlled output is a speed of the tool and the load is a torque applied to the electric motor.   
     
     
         9 . The method according to  claim 8 , further comprising,
 reducing the speed of the motor to an idle speed when the torque is low or no longer applied.   
     
     
         10 . The method according to  claim 8 ,
 wherein the idle speed is 300 rpm and the torque is 0.5 ozf·in or below.   
     
     
         11 . A motor driven dental handpiece having a motor control for driving a motor comprising:
 an electric motor;   a tool engagably connected to said electric motor,   an outer sheath;   an inner module wholly or partially covered by the outer sheath and detachably engaging with said tool;   a microprocessor, and   a current sense circuitry,   wherein the handpiece is constructed such that a load applied to the electric motor corresponds to a controlled output goal of the tool,   wherein a controlled output of the motor increases or decreases to said controlled output goal in response to said load,   wherein said load is an increasing or a decreasing load,   wherein the motor control is constructed to allow the operator to operably control the motor operating speed based on a torsional load exerted on the motor, an observed time delay and a hysteresis current threshold.   
     
     
         12 . The motor driven dental handpiece of  claim 11 ,
 wherein the controlled output is a speed of the tool and the load is a torque applied to the motor.   
     
     
         13 . The motor driven dental handpiece of  claim 12 ,
 wherein the time delay is a predetermined time period and wherein the hysteresis current threshold is a predetermined hysteresis current threshold.   
     
     
         14 . A method of controlling a motor driven dental handpiece having a motor control for driving a motor for dental treatment comprising:
 applying a tool of the handpiece to a tooth to generate a load,   applying said load to an electric motor of the handpiece,   increasing or decreasing a controlled output of the tool of the handpiece to a controlled output goal corresponding to said load,   wherein the increasing or decreasing is also according to a sustenance, over a predetermined time period, of a change in a motor current above a predetermined hysteresis current threshold.   
     
     
         15 . The method according to  claim 14 ,
 wherein the controlled output is a speed of the tool and the load is a torque applied to the motor.   
     
     
         16 . The method according to  claim 15 ,
 wherein the speed is increased for an increasing torque and decreased for a decreasing torque.   
     
     
         17 . The method according to  claim 15 , further comprising
 selecting a new speed based on a new motor current operating point if said change in the motor current is greater than the predetermined hysteresis current threshold   
     
     
         18 . The method according to  claim 15 , further comprising,
 reducing the speed of the motor to an idle speed when the torque is low or no longer applied.   
     
     
         19 . The method according to  claim 15 , further comprising,
 observing a maximum preset speed of the motor beyond which said speed cannot increase.   
     
     
         20 . The method according to  claim 15 , further comprising,
 overriding the motor control through wireless radio communication such as through secured RF protocol with a cordless foot pedal.   
     
     
         21 . The method according to  claim 15 , further comprising,
 controlling the motor speed by a combination of a plurality or predetermined or variable time periods and hysteresis current thresholds.   
     
     
         22 . The method according to  claim 15 , further comprising,
 maintaining the speed within 300 amp and 3200 rpm as the torque varies between 0.5 ozf-in to 1.3 ozf-in.   
     
     
         23 . The method according to  claim 16 ,
 wherein the increase or decrease can be in as few as two steps, on/off, or in many steps, or in a constant or variable proportional to the torque.   
     
     
         24 . The method according to  claim 17 , further comprising,
 determining and updating an upper hysteresis limit current and a lower hysteresis limit current based on said predetermined hysteresis current threshold, wherein if the new motor current operating point is greater than the upper hysteresis limit current or lower than the lower hysteresis limit current, a new upper hysteresis limit current and lower hysteresis limit current are set.