Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C17/00—Devices for cleaning, polishing, rinsing or drying teeth, teeth cavities or prostheses; Saliva removers; Dental appliances for receiving spittle
  • A61C17/16—Power-driven cleaning or polishing devices
  • A61C17/22—Power-driven cleaning or polishing devices with brushes, cushions, cups, or the like
• • A—HUMAN NECESSITIES
  • A46—BRUSHWARE
  • A46B—BRUSHES
  • A46B15/00—Other brushes; Brushes with additional arrangements
  • A46B15/0002—Arrangements for enhancing monitoring or controlling the brushing process
  • A46B15/0004—Arrangements for enhancing monitoring or controlling the brushing process with a controlling means
  • A46B15/0012—Arrangements for enhancing monitoring or controlling the brushing process with a controlling means with a pressure controlling device
• • A—HUMAN NECESSITIES
  • A46—BRUSHWARE
  • A46B—BRUSHES
  • A46B15/00—Other brushes; Brushes with additional arrangements
  • A46B15/0002—Arrangements for enhancing monitoring or controlling the brushing process
  • A46B15/0038—Arrangements for enhancing monitoring or controlling the brushing process with signalling means
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C17/00—Devices for cleaning, polishing, rinsing or drying teeth, teeth cavities or prostheses; Saliva removers; Dental appliances for receiving spittle
  • A61C17/16—Power-driven cleaning or polishing devices
  • A61C17/22—Power-driven cleaning or polishing devices with brushes, cushions, cups, or the like
  • A61C17/221—Control arrangements therefor
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C17/00—Devices for cleaning, polishing, rinsing or drying teeth, teeth cavities or prostheses; Saliva removers; Dental appliances for receiving spittle
  • A61C17/16—Power-driven cleaning or polishing devices
  • A61C17/22—Power-driven cleaning or polishing devices with brushes, cushions, cups, or the like
  • A61C17/225—Handles or details thereof

Definitions

• This invention relates generally to power toothbrushes with bristle pressure sensors, and more specifically concerns such a toothbrush with improved pressure sensing accuracy.
• a pressure sensor is well known in power toothbrushes.
• Such sensors also referred to as load sensors, actually measure force, in grams, which the bristle field applies to the teeth.
• load sensors actually measure force, in grams, which the bristle field applies to the teeth.
• the results of such sensors typically include other types of loads, such as loads produced by the cheek, tongue and lips, in addition to direct bristle force against the teeth produced by user action.
• An accurate indication of bristle pressure against the teeth, apart from the other loads, would provide better information for the user as well as adapt the appliance for better effectiveness.
• a power toothbrush with a pressure sensor comprises: a system for determining pressure applied against a user's teeth by bristles of the toothbrush by a direct force measurement; a system for determining pressure applied against the user's teeth by the bristles of the toothbrush by a dynamic force measurement and a processing system responsive to the pressure determined by the direct force measurement and the dynamic force measurement to adjust the pre-established amount of pressure indicative of excessive bristle force.
• Figure 1 is a plan view of various portions of the mouth of a user and a toothbrush when the exterior (buccal) surfaces of the teeth are being brushed.
• Figure 2 is an elevational view of Figure 1.
• Figure 3 is a plan view of the mouth of a user and a toothbrush when the interior (lingual) surfaces of the teeth are being brushed.
• Figure 4 is a top view of the mouth of Figure 3.
• Figure 5 is a simplified diagram of a portion of a toothbrush producing pressure information.
• Figure 6 is an output of a half-cycle o a Hall effect sensor with an output signal calibrated to the drive signal for the appliance.
• Figure 7 is a diagram similar to that of Figure 6 showing a phase shift in the output signal due to load.
• Figure 8 is a processing diagram producing direct force information from the sensor of Figure 5.
• Figure 9 is a processing diagram for determining dynamic force information from the sensor of Figure 5.
• Figure 10 is a chart which shows how the information from Figure 6 and 7 is used to adjust trigger point/threshold values of excessive force applied by the user.
• FIGS 1 and 2 For the exterior (buccal) surfaces of the teeth, while Figures 3 and 4 show the load for the interior (lingual) surfaces.
• the teeth are illustrated at 12, the cheek is shown at 14, the tongue at 16 and the lips at 18.
• the toothbrush is shown generally at 20, with a neck portion of the toothbrush shown at 22, a bristle plate portion at 24, and the bristles at 28.
• Pressure sensor systems attempting to measure force/load of the bristles against the teeth in order to provide to the user information concerning the application of excessive force relative to possible pressure on it, as well as minimum force for cleansing effectiveness, such sensors, however, actually measure more than just bristle pressure against the teeth and therefore provide somewhat inaccurate information to the user relative to excessive pressure.
• the trigger point (threshold) for producing the excessive pressure indication to the user may be too high or too low. If too high, harm may be caused without warning, and if too low, effectiveness can be decreased.
• the present invention is designed to provide more accurate and informed trigger point information to the user, in particular more accurate/definitive information concerning the pressure or force applied to the surface of the teeth by the bristles.
• two different force determination systems are used and the information obtained from each system is used relative to a table to affect the information provided to the user relative to a possible overload or excessive pressure.
• the information provided by the two different pressure sensor systems, as well as information concerning peak-to-peak values, is used to adjust the pre-set value at which a warning is provided to the user.
• One pressure sensing system provides direct force or displacement information, while the other sensing system provides dynamic force information.
• sensing arrangements which provide a direct force or displacement information and arrangements which provide dynamic force information, as well as peak-to-peak information.
• the direct force or displacement information is provided by a Hall effect sensor arrangement
• the dynamic load information is provided also by a Hall effect sensor used to measure phase shift between the magnetic field response relative to the phase of the drive signal.
• Other arrangements can be used, however, to provide the displacement and dynamic load sensing information.
• Figure 1 shows a simplified view of a power toothbrush arranged to include a Hall effect sensing arrangement to produce both displacement and dynamic load information.
• the power toothbrush shown generally at 29 includes a handle 30, a brushhead assembly 32 and a set of bristles 34, with a bristle plate 36 positioned at the distal end of a neck portion 37 of the brushhead assembly.
• the brushhead assembly is typically removable from the handle portion.
• the power toothbrush includes a drive train assembly shown very generally at 40 powered by a rechargeable battery.
• the power toothbrush further includes a microprocessor 46 which produces the drive signal for the drive train and also processes the signal information from the Hall effect sensor/sensors to provide displacement and dynamic load information.
• a magnet 48 At the rear of drive train 40.
• the magnet has the following dimensions: 13.4 mm by 9.0 mm by 4.0 mm.
• a suitable magnet is neodymium.
• Other magnets can be used.
• Mounted within the power toothbrush is a Hall-effect sensor or sensors 52.
• the Hall-effect sensors 52 can be mounted in various positions within the power toothbrush.
• one Hall-effect sensor is mounted on a flex circuit which is attached to the printed circuit board containing the microprocessor, so that the Hall-effect sensor can respond to a changing magnetic field as the toothbrush moves in operation. This results in a dynamic force determination, as explained below.
• Another Hall-effect sensor 53 can be mounted on the drive train frame of the toothbrush located approximately 2.3 mm from the magnet, in approximately the same plane thereof.
• This Hall-effect sensor recognizes the lateral displacement of the drive train due to force on the bristle field against the teeth, mounted or arranged, such as in a V-spring embodiment, so that the rear end of the drive train moves laterally in response to user force.
• the voltage output of Hall-effect sensor 53 varies sinusoidally.
• the voltage output of the Hall- effect sensor will vary in accordance to a changing magnetic field.
• the changing magnet field provides a basis for determining the amount of force applied to the bristles relative to displacement.
• the rear end of the drive train pivots, including the magnet, producing a lateral displacement of the magnet in the direction of the Hall-effect sensor.
• the Hall-effect sensor is sensitive enough to detect a change in the magnetic field as the magnet comes closer to the sensor.
• the microprocessor in the toothbrush includes a table of information in the form of a response curve which relates to the voltage output of the Hall-effect sensor to the displacement of the magnet and hence the force applied to the brush element.
• the displacement of the magnet will result in a change of voltage output of the Hall-effect sensor relative to the voltage output under no-load conditions. Accordingly, the change in the sensor output is a reliable indication of the displacement force being applied to the bristle field.
• a sinusoidal output is also produced by the Hall-effect sensor under no-load conditions.
• the Hall-effect sensor detects a change in phase between the drive signal for the appliance and the mechanical response of the brushhead assembly produced by movement of the magnet 48 as pressure on the bristle field changes. As pressure increases the phase shift increases.
• the change in phase will be linear over a defined change of pressure (force), such as from 0 grams to at least 300 grams, at which point the pressure has typically exceeded a maximum value for comfort and effectiveness.
• Information is also stored in the microprocessor which specifically relates phase shift information and values to force applied, for the particular appliance being tested, so that a specific phase shift is accurately indicative of pressure/force applied to the bristle field of that toothbrush, specifically the dynamic force.
• the drive signal is typically a square wave, which in one cycle rises from a zero level to a positive value and after a time determined by the drive frequency declines to a value of opposing polarity, which drive signal cycle continues for the duration of operation of the toothbrush for each event.
• the drive frequency is 250 Hz
• the amplitude of motion is between 9-11°. This is, however, only one example of operation. The frequency and amplitude may be varied.
• the toothbrush is initially calibrated to determine a time offset which exists between the square wave motor drive signal and the mechanical response signal, as indicated by the signal output from the Hall sensor. This is done under no-load conditions, so that the static phase relationship between the motor drive signal and the response signal is known and can be in effect a zero set for signal processing during actual operation of the toothbrush.
• Figure 6 shows a single half-cycle of the response signal (Hall sensor output) with the left-hand edge of the signal synchronized to the rising edge of the motor drive signal.
• a phase shift 49) is illustrated in Figure 7.
• the value of the phase shift is determined continuously as load is applied to the bristle field.
• the zero threshold is determined by averaging the signal over a number of cycles. The time from the start of the motor drive cycle to the first transition of the sensor signal through this zero threshold is then measured. The zero crossing provides an indication of the phase shift.
• phase shift information is by a quadrature sampling process, in which four samples are used per cycle to extract the DC offset and phase of a sine wave. Four samples are taken 90° apart, in the calculation below by Si, S 2 , and S 4 .
• the average voltage, or the DC offset can be calculated:
• the signals will typically include noise, so that multiple samples are typically averaged to smooth results.
• two samples of in-phase and quadrature phase are defined as follows:
• phase angle being defined as:
• Averaging I and Q over multiple samples is effective to reduce noise.
• Figure 8 shows the processing of the direct force (displacement) signal information.
• the user action is represented at block 66, indicating the amount of force actually applied by the user.
• the total load action is represented at 67, which includes loads other than bristle pressure on the teeth.
• the displacement produced at the rear end of the drive train and the magnet is represented by block 68.
• the displacement produces a signal from the Hall-effect sensor as represented by block 70.
• the Hall-effect output signal is then processed at block 74, determining the change in the voltage and output due to the total load.
• the processing includes averaging the output over a number of cycles, referred to at 76, as well as filtering noise from the signal, including electronic noise and mechanical noise from the motor, which is represented at 78.
• the microprocessor includes a response curve or table of information 81 which relates Hall-effect sensor output to a particular displacement force value.
• the response curve is typically a straight line for an average of 0-300 grams of force.
• This calculation will include a correlation step represented at 84, which involves correlation of force and Hall sensor values over the force range. Information is provided continuously.
• the Hall-effect dynamic load (phase shift) sensing system ( Figure 9) also includes generally the pressure applied by the user. 90 as well a total load 92 which occurs during brushing.
• the total dynamic load creates phase shift between the motor drive signal and the Hall sensor output signal which represents the response of the system.
• the Hall sensor output is shown at 98.
• the sensor output signal is affected by signal noise 100 which can be from various sources including the Hall sensor itself as well as variations in mounting or a change in the resonant system over time. Hall sensor output is also sensitive to dynamic noise 100, which typically is produced by the vibration from a drive train.
• the Hall sensor output is then processed at 104, which can include filtering 106 and averaging 108 to produce a clean output signal. This signal represented as output 104 is subject to further processing.
• the actual phase shift is determined at 1 12. As indicated above, the phase shift can be determined by a standard zero crossing circuit or by other arrangements. The phase shift is determined for a calibrated appliance.
• the processor uses the phase shift to calculate the dynamic pressure by use of stored information 114 which relates phase shift along one axis to pressure along the other axis. The pressure resulting from the phase shift circuit is shown at 116.
• Peak-to-peak movement of the bristle motion can also be determined by one or the other pressure measurement systems.
• the response curve is a straight line for phase shift against dynamic pressure over at least a range of pressure force of 0-300 grams.
• the results from the displacement (direct force) arrangement will provide a different result than the dynamic force (phase shift) pressure information.
• These two results are then compared against a table which is shown in Figure 10, to determine the resulting effect relative to a pre-set trigger point, i.e. 300 grams, or other set value.
• the loads produced by the various portions of the mouth are shown in column 120.
• the direct or displacement load measurement When the direct or displacement load measurement is approximately zero, the phase shift is low, and the peak to peak is a low decrease, there will be no trigger.
• the direct load measurement When the direct load measurement is approximately zero, the phase shift is low and the peak to peak indicates a medium decrease, the trigger point is decreased.
• the direct load measurement is positive, the phase shift is medium and the peak to peak indicates a medium decrease, the trigger point pressure remains unchanged.
• the trigger point When the displacement load information is approximately zero, the phase shift is low, and the peak to peak decrease is high, the trigger point will be decreased.
• the particular amounts in each case will depend upon the characteristics of the individual appliance. The result is more accurate information for the user relative to the use of excessive force for the bristles against the teeth and gums.

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• Health & Medical Sciences (AREA)
• Dentistry (AREA)
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• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Brushes (AREA)
• Measuring Fluid Pressure (AREA)

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Cited By (6)

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• 2013
  • 2013-12-18 BR BR112015015225A patent/BR112015015225A2/pt not_active IP Right Cessation
  • 2013-12-18 TR TR2019/00933T patent/TR201900933T4/tr unknown
  • 2013-12-18 EP EP13828937.6A patent/EP2938288B1/en active Active
  • 2013-12-18 US US14/652,810 patent/US9259302B2/en active Active
  • 2013-12-18 JP JP2015550177A patent/JP6393276B2/ja active Active
  • 2013-12-18 RU RU2015131132A patent/RU2657956C2/ru active
  • 2013-12-18 WO PCT/IB2013/061060 patent/WO2014102667A1/en not_active Ceased
  • 2013-12-18 CN CN201380068305.XA patent/CN104883997B/zh active Active

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