U.S. patent application number 16/749627 was filed with the patent office on 2020-05-21 for illuminating feedback during teeth cleaning.
The applicant listed for this patent is WATER PIK, INC.. Invention is credited to John Fiers, Harold A. Luettgen, Brian R. Williams.
Application Number | 20200155286 16/749627 |
Document ID | / |
Family ID | 60242758 |
Filed Date | 2020-05-21 |
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United States Patent
Application |
20200155286 |
Kind Code |
A1 |
Luettgen; Harold A. ; et
al. |
May 21, 2020 |
ILLUMINATING FEEDBACK DURING TEETH CLEANING
Abstract
A toothbrush is disclosed. The toothbrush includes a handle, a
brush tip coupled to the handle, the brush tip including a
plurality of bristles, a motor housed within the handle for
operating the brush tip, a power source coupled to the motor, one
or more lights coupled to the handle and viewable by a user when
holding the handle, and a control module housed within the handle
and in communication with the one or more lights, wherein the
control module is configured to monitor a pressure exerted by the
brush tip on a surface, determine when the exerted pressure exceeds
a pressure threshold, and, in response to the exerted pressure
exceeding the pressure threshold, activate the one or more lights
to alert the user that the exerted pressure exceeds the pressure
threshold.
Inventors: |
Luettgen; Harold A.;
(Windsor, CO) ; Fiers; John; (Fort Collins,
CO) ; Williams; Brian R.; (Fort Collins, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WATER PIK, INC. |
Fort Collins |
CO |
US |
|
|
Family ID: |
60242758 |
Appl. No.: |
16/749627 |
Filed: |
January 22, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15588842 |
May 8, 2017 |
10561480 |
|
|
16749627 |
|
|
|
|
62333679 |
May 9, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61C 17/3436 20130101;
A61C 17/24 20130101; A61C 17/221 20130101; A61C 17/3418 20130101;
A46B 15/0012 20130101; G01L 5/22 20130101 |
International
Class: |
A61C 17/22 20060101
A61C017/22; A61C 17/24 20060101 A61C017/24; A61C 17/34 20060101
A61C017/34; G01L 5/22 20060101 G01L005/22; A46B 15/00 20060101
A46B015/00 |
Claims
1. A toothbrush comprising: a handle; a brush tip coupled to the
handle, the brush tip including a plurality of bristles; a motor
housed within the handle for operating the brush tip; a power
source coupled to the motor; one or more lights coupled to the
handle and viewable by a user when holding the handle; and a
control module housed within the handle and in communication with
the one or more lights, wherein the control module is configured
to: monitor a pressure exerted by the brush tip on a surface;
determine when the exerted pressure exceeds a pressure threshold;
and in response to the exerted pressure exceeding the pressure
threshold, activate the one or more lights to alert the user that
the exerted pressure exceeds the pressure threshold.
2. The toothbrush of claim 1, wherein the one or more lights are
one or more light emitting diodes.
3. The toothbrush of claim 1, wherein the pressure threshold is an
absolute pressure magnitude value or a delta pressure value.
4. The toothbrush of claim 1, wherein the control module determines
the pressure exerted by the brush tip by directly measuring force
applied to the plurality of bristles.
5. The toothbrush of claim 1, wherein the control module determines
the pressure exerted by the brush tip by indirectly measuring force
applied to the plurality of bristles.
6. The toothbrush of claim 1, wherein the control module detects
electrical current drawn by the motor and determines the exerted
pressure based on the detected electrical current.
7. The toothbrush of claim 1, wherein the control module comprises
one or more memory components that store the pressure
threshold.
8. The toothbrush of claim 1, wherein the pressure threshold is
between about 280 to about 430 g/cm.sup.2.
9. The toothbrush of claim 1, wherein the pressure threshold is
about 140 g/cm.sup.2.
10. The toothbrush of claim 1, wherein the one or more lights
provide feedback to a user to reduce pressure exerted by the brush
tip.
11. A method of alerting a user of excessive pressure exerted by a
toothbrush during teeth cleaning, comprising: determining a
pressure exerted by bristles coupled to the toothbrush while the
user is brushing teeth; determining that the exerted pressure is
excessive; and activating a light on a handle of the toothbrush to
provide feedback to the user that the pressure is excessive.
12. The method of claim 11, wherein the light is a light emitting
diode.
13. The method of claim 11, wherein determining that the exerted
pressure is excessive comprises determining that the exerted
pressure exceeds a pressure threshold value.
14. The method of claim 11, wherein determining the pressure
exerted by the bristles comprises directly measuring force applied
to the bristles.
15. The method of claim 11, wherein determining the pressure
exerted by the bristles comprises indirectly measuring force
applied to the bristles.
16. The method of claim 11, wherein determining the pressure
exerted by the bristles comprises detecting current drawn by a
motor coupled to the bristles and correlating the detected current
to a pressure value.
17. The method of claim 13, further comprising retrieving, from
memory stored by the toothbrush, the pressure threshold value.
18. The method of claim 13, wherein the pressure threshold value is
between about 280 to about 430 g/cm.sup.2.
19. The method of claim 13, wherein the pressure threshold value is
about 140 g/cm.sup.2.
20. A toothbrush comprising: a handle; a brush tip including a
plurality of bristles releasably coupled thereto; a motor received
within the housing; a light coupled to the housing; and a control
module positioned within the housing and in electrical
communication with the light, wherein the control module is
configured to: determine a pressure applied by the bristles to a
tooth surface; and illuminate the light in response to the pressure
being above a desired level.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
Non-Provisional application Ser. No. 15/588,842, entitled "Load
Sensing for Oral Devices" filed May 8, 2017, which claims priority
to U.S. Provisional Application No. 62/333,679 entitled "Load
Sensing for Oral Devices" filed on May 9, 2016, both of which are
hereby incorporated by reference herein in their entireties.
TECHNICAL FIELD
[0002] The present disclosure relates to oral health products. More
specifically, the present disclosure relates to toothbrush
systems.
BACKGROUND
[0003] Many people use electronically driven toothbrushes as part
of a daily oral health routine. Electronically driven toothbrushes
typically rotate or oscillate a brush head include one or more
bristle groups. While electronic toothbrushes can provide superior
cleaning capabilities as compared to conventional non-powered
toothbrushes, many users will exert an additional force on the
brush head during cleaning. This user applied force, in addition to
the force exerted by the stiffness and electronic movement of the
bristles, can damage the gums of a user. Therefore, it is desirable
to ensure that the force of the bristles on a user's gums remains
below a particular level. However, many conventional electronically
driven toothbrushes do not have a way to monitor or change the
pressure exerted on a user's gums.
[0004] The information included in this Background section of the
specification, including any references cited herein and any
description or discussion thereof, is included for technical
reference purposes only and is not to be regarded subject matter by
which the scope of the invention as defined in the claims is to be
bound.
SUMMARY
[0005] In one embodiment, a toothbrush including a pressure sensing
function is disclosed. The toothbrush may include a handle and a
brush tip releasably connected to the handle, where the brush tip
includes multiple bristles connected thereto and rotatable
therewith. The toothbrush may also include a power source, a direct
current motor in selective communication with the power source, a
drive assembly connected between the brush tip and a drive shaft
that converts rotation of the direct current motor into oscillation
or rotation of the brush tip, and a control assembly in electrical
communication with the power source. During operation of the motor,
the control assembly monitors a current draw by the motor to assess
the pressure being exerted by the bristles on one or more surfaces
of a user's mouth and adjusts a current applied to the direct
current motor based on the current draw.
[0006] In another embodiment, a toothbrush including a pressure
sensing function is disclosed. The toothbrush includes a brush tip
comprising a plurality of bristles operably coupled thereto, a
motor that actuates the brush tip, the plurality of bristles, or a
combination thereof, a power source that provides current to the
motor, a sensing module that detects a current provided to the
motor, and a motor control coupled to the motor and the sensing
module, wherein the motor control dynamically adjusts a current
provided to the motor based on the detected current.
[0007] In another embodiment, a method of operating a toothbrush is
disclosed. The method includes detecting, by a sensing module, a
current provided to a motor driving a plurality of bristles on a
brush tip, wherein the detected current is proportional to a
pressure applied to the plurality of bristles, determining, by a
processor, whether the detected current exceeds a threshold
current, and providing an alert to a user responsive to determining
that the detected current exceeds the threshold.
[0008] In another embodiment, a toothbrush is disclosed. The
toothbrush includes a handle, a brush tip coupled to the handle,
the brush tip including a plurality of bristles, a motor housed
within the handle for operating the brush tip, a power source
coupled to the motor, one or more lights coupled to the handle and
viewable by a user when holding the handle, and a control module
housed within the handle and in communication with the one or more
lights. The control module is configured to monitor a pressure
exerted by the brush tip on a surface, determine when the exerted
pressure exceeds a pressure threshold, and, in response to the
exerted pressure exceeding the pressure threshold, activate the one
or more lights to alert the user that the exerted pressure exceeds
the pressure threshold.
[0009] In another embodiment, a method of alerting a user of
excessive pressure exerted by a toothbrush during teeth cleaning is
disclosed. The method includes determining a pressure exerted by
bristles coupled to the toothbrush while the user is brushing
teeth, determining that the exerted pressure is excessive, and
activating a light on the toothbrush handle to provide feedback to
the user that the pressure is excessive.
[0010] In another embodiment, a toothbrush is disclosed. The
toothbrush includes a handle, a brush tip including a plurality of
bristles releasably coupled thereto, a motor received within the
housing, a light coupled to the housing, and a control module
positioned within the housing and in electrical communication with
the light. The control module is configured to determine a pressure
applied by the bristles to a tooth surface, and illuminate the
light in response to the pressure being above a desired level.
[0011] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used to limit the scope of the claimed
subject matter. A more extensive presentation of features, details,
utilities, and advantages of the present invention as defined in
the claims is provided in the following written description of
various embodiments of the invention and illustrated in the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a front elevation view of a toothbrush including a
load sensing function.
[0013] FIG. 2 is a simplified block diagram of the electrically
connected components of the toothbrush of FIG. 1.
[0014] FIG. 3 is a wiring diagram of a feedback loop for sensing
the pressure applied to the bristles of the toothbrush.
[0015] FIG. 4 is a graph illustrating a relationship between motor
current and pressure that can be used to adjust operation of the
toothbrush.
[0016] FIG. 5 is a flow chart illustrating a method for using the
pressure-current relationship of FIG. 4 and the feedback loop of
FIG. 3 to adjust operation of the toothbrush of FIG. 1.
DETAILED DESCRIPTION
Overview
[0017] The present disclosure is generally related to a system and
method to sense an applied load on a brush tip or bristles. Using
this method, a toothbrush can provide an alert to a user to
indicate that he or she has exceeded a desired force level and/or
may automatically adjust one or more characteristics of the system
to reduce the applied force, e.g., reduce the power applied to a
motor driving the brush tip.
[0018] In one example, a toothbrush including a sensing module is
disclosed. The toothbrush includes a direct-current (DC) driven
motor, a drive assembly connected to and rotated by the motor, a
power assembly for providing power to the motor, and a brush head
or bristles connected to the drive assembly and configured to be
oscillated or rotated by the drive assembly. In this example, the
sensing module may monitor the voltage drop across the motor (e.g.,
by measuring the current that the motor is pulling from the power
source) and use the value to determine the force being applied to a
user's gums. In some embodiments, the sensing module may include
parameters such as, but not limited to, type of brush tip, bristle
stiffness, bristle height, no-load values, and the like. These
additional parameters may assist in providing a more accurate
reading for the toothbrush.
[0019] In a specific embodiment, the sensing module may monitor the
voltage across a wire connected to the motor. Additionally or
alternatively, the sensing module may monitor the voltage of an
activating transistor electrically connected to the motor. The
sensing modules may be connected to either or both the positive and
negative terminals of the motor.
[0020] In some embodiments, the sensing module may analyze the
detected values against a predetermined current/force relationship.
In one embodiment, a linear slope relationship may be used to
determine the force applied to the brush tip based on the current
applied to the motor. In this example, as soon as the user applies
the bristles of the brush tip to a surface in his or her mouth
(e.g., gums, teeth, tongue, etc.), the sensing module tracks the
current in real-time to adaptively track the motor load and thus
the brush tip load, as it varies. An output to the user or a
modification to the motor speed may occur when a detected load
change exceeds a predetermined threshold, e.g., magnitude or change
value. In some embodiments, the toothbrush may dynamically
calculate a threshold level of pressure for a particular brush,
using a current/force relationship, e.g., adaptive learning, and
use this threshold to detect when the force may damage a user's
gums. This helps to accommodate for changes based on wear on the
components, bristles, new brush heads, and the like. If the
threshold was based solely on a static level, rather than a dynamic
relationship, then the threshold may not compensate for
increases/decreases in friction and other changes in the
brushes.
DETAILED DESCRIPTION
[0021] Turning now to the figures, the method and system will be
discussed in more detail below. FIG. 1 illustrates a simplified
diagram of a toothbrush of the present disclosure. FIG. 2 is a
simplified electronic block diagram of the toothbrush of FIG. 1.
With reference to FIGS. 1 and 2, the toothbrush 100 may include a
handle 102 and a brush tip 104 including a brush head 106 having a
plurality of bristles 108 connected thereto. The brush tip 104 is
driven by an output shaft 110 connected to a drive assembly 116,
which is connected via a drive shaft 114 to a motor 112. The motor
112 is powered by a power source 118 and is controlled by a control
assembly 126 that may include user inputs through one or more
control buttons 120. Each of the components will be discussed, in
turn, below.
[0022] The handle 102 defines a main body of the toothbrush 100 and
acts to house the various internal components (e.g., motor 112,
drive assembly 116, etc.). In many embodiments the handle 102 may
be formed by two shells that are connected together to define an
internal cavity. However, in other embodiments the handle 102 may
be differently configured. In some embodiments the toothbrush 100
may also include a washing or irrigating function and in these
embodiments the handle 102 may include a fluid connection to a
reservoir or the like, as well as one or more fluid pathways
defined therein or connected thereto, that transfer fluid from the
reservoir to the brush tip 104.
[0023] The brush head 104 is movable relative to the handle 102 and
may be removably connected to a top end of the handle 102. The
brush tip 104 is connected to the output shaft 110 which drives the
brush head 104 in an oscillating motion (e.g., back and forth about
a pivot point) or to drive the brush head 106 in a rotational
movement relative to the handle 102. The brush tip 104 includes a
plurality of bristles 108 that are connected to the brush head 106.
The bristles 108 may be uniform or may have varying heights,
stiffness, and/or materials in order to provide a desired output
characteristic. As will be discussed in more detail below, in some
embodiments various characteristics of the bristles 108 may be
provided as an input or otherwise adjusted for by the toothbrush
100 when determining a desired motor 112 speed. For example, the
stiffer the bristles 108 the slower the motor 112 may need to
rotate to achieve a desired exertion force on a user's teeth and
gums. It should be noted that in some embodiments, the entire brush
head 104 may move in order to move the bristles 108
correspondingly. In other examples, the brush head 104 may connect
to a bristle head or carrier that supports the bristles. In these
examples, the bristle carrier only may move and the brush head may
remain stationary.
[0024] The motor 112 is used to drive the brush tip 104 and/or
brush head 106. In many embodiments the motor 112 is a high speed
DC motor that, when activated, rotates the drive shaft 114 in a
continuous manner. In some embodiments, the drive shaft 114 may be
an eccentric shaft having one portion aligned with a center axis of
the motor 112 and one portion offset from the center axis of the
motor 112. In other embodiments, the drive shaft 114 may be
straight and be aligned with the center axis of the motor 112. In
some embodiments, the motor will rotate between 5500 to 16000 rpms
depending on whether sonic or sub-sonic rotary motion is desired.
In one example, a DC motor having a maximum efficiency load of 6900
rpms, a no-load speed of 8300 rpm, and a loaded speed of 5500 rpms
may be used. However, in other embodiments, other speeds may be
used and may vary depending on the desired output characteristics
of the toothbrush 100. For example, using a direct drive assembly
116, the motor 112 may operate at higher speeds, such as 16000
rpms. In some embodiments, the motor 112 may operate with a voltage
range between 2.4 to 8.7 Volts. However, in other embodiments other
voltage ranges may be used.
[0025] The drive assembly 116 converts rotation of the drive shaft
114 into a desired output motion of the brush tip 104 and/or brush
head 106. For example, the drive assembly 116 may convert the
rotational movement of the drive shaft 114 into an oscillating
movement of the brush tip 104. In another embodiment, the drive
assembly 116 may transfer rotary motion of the drive shaft 114 into
rotational movement of the brush head 106 relative to the brush tip
104. The drive assembly 116 may be a direct drive configuration or
may be an indirect configuration (e.g., gear reduction or the
like). Additionally, the drive assembly 116 may reduce the speed of
the movement as compared to the rotational speed of the drive shaft
114. Examples of drive assemblies 116 that may be used with the
toothbrush 100 may be found in U.S. patent application Ser. No.
13/833,897 entitled "Electronic Toothbrush with Vibration
Dampening," filed on Mar. 15, 2013, U.S. Pat. No. 8,943,634
entitled "Mechanically-Driven, Sonic Toothbrush System," filed on
May 2, 2012, U.S. patent application Ser. No. 14/216,779 entitled
"Mechanically-Driven, Sonic Toothbrush and Water Flosser" filed on
Mar. 17, 2014, and U.S. Provisional Application No. 62/190,094
entitled "Irrigating Toothbrush" filed on Jul. 8, 2015, each of
which are hereby incorporated by reference in their entireties.
[0026] The output shaft 110 is connected to the drive assembly 116
and may include two or more shafts connected together. The output
shaft 110 may be inserted into a cavity in the brush tip 104 to
drive the motion of the brush tip 104 or may connect to an internal
shaft within the brush tip 104.
[0027] The power source 118 provides power to the motor 112, as
well as other components of the toothbrush 100 that may require
power (e.g., control assembly 126, output elements 128, lights, or
the like). In some embodiments the power source 118 may be a
battery (either rechargeable or replaceable), in other embodiments
the power source 118 may be a power cord or the like that connects
to an external power source (e.g., wall outlet).
[0028] The control buttons 120 allow a user to provide input to
control the operation of the motor 112. For example, the control
buttons 120 may include a power button to allow a user to activate
the motor 112. Additionally the control buttons 120 may include a
speed or setting button that allows a user to increase or decrease
the speed of the motor 112. In embodiments where the toothbrush 100
may have additional functions (e.g., irrigating function), the
control buttons 120 may also change the functionality of the
toothbrush 100, such as activating the fluid flow.
[0029] With reference to FIG. 2, the control assembly 126 will be
discussed in more detail. The control assembly 126 is
electronically connected to the motor 112, the power source 118,
the control buttons 120, and one or more output elements 128 (e.g.,
light emitting diodes, speaker, vibrating motor, or the like). The
control assembly 126 controls operation of the motor 112 and thus
the output characteristics of the brush tip 104 and bristles 108.
The control assembly 126 may include a motor control 124 that may
include one or more processing elements (e.g., microprocessors)
that vary the input signals to the motor 112 to provide a desired
output, such as by providing a higher or lower voltage or a pulse
width modulated signal. The control assembly 126 may also include
one or more sensing modules 122 that directly or indirectly measure
the force applied to the bristles 108 and one or more memory
components 125 that store pressure thresholds and/or brush tip 104
characteristics.
[0030] The sensing module 122 provides feedback to the motor
control 124 regarding the operation of the brush tip 104 and can be
used to automatically vary the output of the motor 112 or to
activate the output element 128. In one embodiment, the sensing
module 122 tracks the mechanical load experienced on the bristles
108 by tracking the current applied to the motor 112. In one
example, the sensing module 122 may be an in-series current sense
that monitors the voltage across the motor wire connections (e.g.,
in the connection wire before or after the motor 112, such as the
connection wires on the positive and negative side of the motor
112). For example, the current sense may include a current sensor
(such as an ammeter), a voltage meter, or any other type of device
capable of measuring, directly or indirectly, an electrical
current. As another example, the sensing module 122 may be a
motor-control sense that monitors the voltage of a control switch,
such as a transistor (e.g., field effect transistor (FET)), using
the inherent resistance during the on-state of the transistor
(e.g., drain-source on resistance (R.sub.DS(on)). As yet another
example, the sensing module 122 may include using a sensing
resistor positioned in series with the motor 112 or to add
additional lengths of wire traces to a circuit board including the
various components. However, with the sensing resistor option, a
drop in efficiency may occur due to the introduced loss through the
resistor and therefore may not be desired in some
configurations.
[0031] FIG. 3 illustrates an exemplary wiring diagram for the
toothbrush 100. With reference to FIG. 3, in this embodiment, the
sensing module 122 includes a positive sensing module 130 and a
negative sensing module 132 which together form a feedback loop for
the motor 112 operation. The positive sensing module 130 is
positioned on the positive or high side of the motor 112, e.g.,
electrically connected to the positive terminal of the power source
118. The negative sensing module 132 is connected to the negative
or low side of the motor 112, e.g., electrically connected to the
negative terminal of the power source 118 and motor 112. Either or
both sensing modules 130, 132 may be used to sense the current to
the motor 112 and thus allow the motor control 124 to determine the
load on the motor 112 and adjust accordingly and/or provide an
alert or other output to the user.
[0032] In one embodiment, the positive sensing module 130 is an
in-series current sense that monitors the voltage across the wire
or trace connection 146 from the power source 118 to the positive
terminal of the motor 112. In this example, the positive sensing
module 130 may include a signal amplifier 134 that amplifies the
detected signal before generating a first voltage output 136. As
noted above, in other embodiments, the positive sensing module 130
may be differently configured and may be a current sense, rather
than a voltage reference as shown point in FIG. 3.
[0033] With continued reference to FIG. 3, in this embodiment, the
negative sensing module 132 may be a transistor or control sense.
In this example, the negative sensing module 132 may monitor the
voltage across a transistor 142, which may be a FET, using the
drain-source resistance R.sub.DS(on) when the transistor 142 is in
the on-state (e.g., allowing current to flow through the channel)
and the motor 112 is operating. As with the positive sensing module
130, the negative sensing module 132 may include a signal amplifier
138 that amplifies the detected signal before generating a second
voltage output 140. That is, the sensing module senses amplified
voltages to monitor levels allowing operational closed loop
feedback control.
[0034] As shown in FIG. 3, the voltage outputs 136, 140 may be
supplied as inputs to the motor control 124. As will be discussed
in more detail below, these inputs allow the toothbrush 100, and in
particular, the motor control 124 to alert a user through the
output elements 128 when the applied force exceeds a particular
threshold and/or adjust the operation of the motor 112
accordingly.
[0035] Operation of the toothbrush 100 will now be discussed. With
reference to FIGS. 1 and 2, when a user provides an input to the
control buttons 120, a switch is closed to electrically connect the
motor 112 to the power source 118. In some embodiments, the voltage
level provided to the motor 112 is selected by the motor control
124. When powered, the motor 112 begins to operate, rotating the
drive shaft 114. Rotation of the drive shaft 114 generates motion
in the drive assembly 116 which converts the motion profile into a
desired output movement. The output shaft 110, which is connected
to the brush tip 104 moves the brush tip 104 in an oscillating or
rotational manner, to move the bristles 108. In some embodiments
the brush tip 104 may be rotated at a sonic speed to enhance
cleaning.
[0036] As the user presses the bristles 108 against surfaces in his
or her mouth, the added pressure provides a counteracting force on
the motor causing the load on the motor 112 to increase. In
particular, the harder the user presses the bristles 108 against a
surface, the more torque the motor 112 may require in order to
continue to rotate the bristles 108 at the desired or selected
speed. In this manner, the current drawn by the motor 112 is
proportional to the load (e.g., the force required to move the
bristles 108), and as the load increases the current drawn by the
motor 112 also increases.
[0037] By analyzing the motor current, along with other factors,
such as characteristics of the brush tip 104, bristles 108 (e.g.,
strand thickness, tuft height (or heights when the brush head has
groups of bristles with different heights), tuft counts, and the
like), drive assembly 116, a relationship between the pressure
exerted onto the applied surface as compared to the current drawn
by the motor can be determined. FIG. 4 illustrates an exemplary
graph illustrating a pressure-current relationship for the motor
112, where the pressure is measured in centimeter/gram/second units
of g/cm.sup.2. As shown in FIG. 4, the pressure exerted on the
interior surface (e.g., gums) of a user is related to the current
drawn (in amps) by the motor 112 in a linear relationship 202.
Using this relationship 202, the toothbrush 100, in particular, a
processing element in the motor control 124, can determine or
estimate the pressure being applied by the bristles 108 by
monitoring the current of the motor 112. Specifically, the
processing element may extrapolate an estimated pressure based on
the detected current. The detected current may be from one or both
sensing modules 130, 132.
[0038] A method for using the pressure-current relationship 202 of
FIG. 4 to adjust operation of the toothbrush 100 will now be
discussed. FIG. 5 is a flow chart illustrating a method 250 for
adjusting the operation of the toothbrush 100. With reference to
FIG. 5, the method 250 may begin with operation 252 and the motor
112 is activated. For example, the use may activate one of the
control buttons 120 which closes a connection between the power
source 118 and the motor 112, providing voltage to the motor 112.
As the motor 112 is activated, the method 250 proceeds to operation
254 and the control assembly 126 determines the current draw by the
motor 112 shortly after start up. In particular, using the sensing
module 122 (e.g., positive sensing module 130 and/or negative
sensing module 132) the control assembly 126 (e.g., a processing
element in the motor control 124) determines the current being
drawn to the motor 112 by assessing the voltage drop across the
motor and various sensing points in the control system 112, 146,
130, 132, 142. Operation 254 may be done just after start-up, since
the initial current to start the motor may be higher than the
no-load current. For example, the initial calibration may be
performed within 50 ms of motor activation.
[0039] Operation 254 uses the motor current as the motor 112 is
first activated to determine the no-load condition of the motor
112. In particular, as soon as the user activates the toothbrush
100, the system assumes that he or she has not yet positioned the
bristles 108 against surfaces in his or her mouth, or if the user
has positioned the bristles 108 against a surface, the pressure
exerted manually by a user is very light. By creating an initial
reading during operation 254, the method 250 can create a baseline
value and account for variations in the toothbrush 100 over time.
For example, normal operation may cause the drive assembly 116 and
output shaft 110 to wear-in, reducing the friction on the motor 112
and thus reducing the no-load conditions on the motor 112. As
another example, as a user's bristles 108 wear due to use or if the
user replaces the brush tip 104 with a different type of brush tip
or with stiffer bristles 108, the method 250 can accommodate for
those changes. As yet another example, factory calibration
conditions may not account for manufacturing tolerances and the
specific characteristics of each toothbrush 100.
[0040] In some embodiments, the method 250 may include determining
a baseline or expected pressure range during operation 254. For
example, some users may place the bristles 108 against their teeth
with some force before turning on the toothbrush 100. In this
example, the initial detected condition may not be a true no-load
and the system may not accurately detect when the actual exerted
pressure exceeds the predetermined pressure thresholds since the
initial baseline reading is incorrect. Accordingly, in these
embodiments, if the initial load is greater than an acceptable
no-load condition (which may be a range of values or threshold), a
default or historical no-load condition is applied to initialize
the readings. The default or historical no-load conditions may be
stored, for example, in the memory 125 and accessed by the motor
control 124 when needed.
[0041] With reference again to FIG. 5, after operation 254, the
method 250 may proceed to operation 256. In operation 256, the
sensing module 122 continues to monitor the load applied to the
motor 112 as the user is using the toothbrush 100. For example,
with reference to FIG. 3, the motor control 124 may use the first
and second voltage outputs 136, 140 to track the pressure exerted
by the user. As the motor control 124 continues to track the
pressure, the method 250 may proceed to operation 258. In operation
258, the motor control 124, e.g., a processing element, determines
whether the pressure exerted by the bristles 108 on a surface
exceeds a predetermined threshold.
[0042] In particular, the motor control 124 may determine the
current being drawn by the motor 112 by evaluating the first
voltage output 136 and/or the second voltage output 140. In some
embodiments only the change in current between the initial value as
determined in operation 254 and the value determined in operation
256 may be evaluated, rather than the full current value. In some
embodiments, signal processing is applied in the control assembly
126 based on singular or sampling average techniques allowing
accurate/stable current readings.
[0043] Using the voltage drop across the motor to determine the
current used by the motor 112, the motor control 124 or other
processor refers a pressure-current relationship, such as the
linear pressure-current relationship shown in FIG. 4 to assess the
output pressure by the bristles 108. In particular, the slope of
the line 202 in FIG. 4 is used to predict the output pressure by
providing an input of the current. In some embodiments, the
threshold may be a pressure value. In other embodiments, the
threshold may be a current change (e.g., current delta) from a
no-load or normal-load current value. The type of threshold may
vary as desired. In some embodiments, the current value
corresponding to a particular pressure value may vary, but the
delta between a baseline or no-load condition and a pressure
threshold may remain constant across various motors. Thus, in some
embodiments, using a delta value, rather than an absolute magnitude
may allow multiple types of motors to be analyzed.
[0044] The threshold value may be stored in a memory component 125
in the motor control 124 or in the control assembly 126 and may be
selected based on characteristics of the brush tip 104, bristles
108, drive assembly 116, or the like. In some embodiments, the
pressure threshold may be between around 280 to 430 g/cm.sup.2.
This pressure range has been found to be sufficient to prevent
damage to a user's gums, while still allowing effective cleaning
and plaque removal. However, in other embodiments, different
pressure thresholds may be selected. For example, depending on the
stiffness of the bristles 108 the threshold may increase or
decrease. In particular, for very stiff bristles 108, the threshold
may reduce to about 140 g/cm.sup.2. In some embodiments, the
toothbrush may include inputs that allow a user to provide
information regarding the characteristics of the brush tip 104 or
user preferences which can be used to set or adjust the pressure
threshold.
[0045] If in operation 258, the pressure exceeds the threshold, the
method 252 may proceed to operation 260. In operation 260, the
control assembly 126 may provide an output to the user. For
example, the output element 128 may be activated to vibrate the
brush handle 102, turn on one or more lights, turn the motor 112
off, produce a buzz or other audible sound, create a stutter motion
by the brush tip 104, or the like.
[0046] The method 252 may also include operation 262. In operation
262, if the pressure exceeds the predetermined threshold, the motor
control 124 may reduce the speed of the motor 112. For example, the
motor control 124 may reduce the current or voltage applied to the
motor 124, which in turn will reduce the rotational speed of the
drive shaft 114. The motor control 124 may adjust the voltage in
various manners, but in one embodiment, the motor control 124 may
include the transistor 142 which can be modulated (e.g., by
modulating a gate condition or a channel condition of the
transistor 142) to vary the motor speed. In other examples, a
rheostat, signal generator, or other components can be used to
provide varying voltage magnitudes to the motor 112. As yet another
example, in one embodiment, a FET is driven in ohmic mode in
combination with a digital potentiometer assembled as an extension
of the motor control transistor 142.
[0047] After operation 262 or if in operation 258 the pressure did
not exceed the threshold, the method 250 may proceed to operation
264. In operation 264, the motor control 124 determines whether the
motor 112 should be deactivated. For example, the motor control 124
may determine whether the control button 120 for powering off the
toothbrush 100 has been activated by a user. As another example,
the toothbrush 100 may operate the motor 112 for a predetermined
amount of time and automatically deactivated the motor 112 when the
time expires. If the motor 112 is to be deactivated, the method 252
proceeds to operation 266 and the power source 118 is disconnected
from the motor 112 to deactivate the motor 112. However, if the
motor 112 is not to be deactivated, the method 252 may return to
operation 256 and continue to monitor the pressure.
[0048] Using the method 250, the toothbrush 100 can provide
adaptive pressure sensing for the DC motor 112, and help to prevent
users from exerting too much pressure on interior surfaces in their
mouths. The adaptive pressure sensing adjusts to accommodate
mechanical and functional changes to the toothbrush, which is not
possible with conventional toothbrushes. In some embodiments, the
method 250 may track, using the sensing module 122, deltas or
changes in current of a motor and uses these data points to adjust
operation of the motor 112 or toothbrush 100. For example, the
processing element may track a delta change from an operating or
no-load current draw by the motor 112. In particular, in some
instances a user's force may generate a consistent change in
current (as compared to a current magnitude) by the motor 112
(e.g., an ampere change between 400 to 650 milliamps).
[0049] All directional references (e.g., proximal, distal, upper,
lower, upward, downward, left, right, lateral, longitudinal, front,
back, top, bottom, above, below, vertical, horizontal, radial,
axial, clockwise, and counterclockwise) are only used for
identification purposes to aid the reader's understanding of the
present invention, and do not create limitations, particularly as
to the position, orientation, or use of the invention. Connection
references (e.g., attached, coupled, connected, and joined) are to
be construed broadly and may include intermediate members between a
collection of elements and relative movement between elements
unless otherwise indicated. As such, connection references do not
necessarily infer that two elements are directly connected and in
fixed relation to each other. The exemplary drawings are for
purposes of illustration only and the dimensions, positions, order
and relative sizes reflected in the drawings attached hereto may
vary.
[0050] The above specification, examples and data provide a
complete description of the structure and use of exemplary
embodiments of the invention as defined in the claims. Although
various embodiments of the claimed invention have been described
above with a certain degree of particularity, or with reference to
one or more individual embodiments, those skilled in the art could
make numerous alterations to the disclosed embodiments without
departing from the spirit or scope of the claimed invention. Other
embodiments are therefore contemplated. It is intended that all
matter contained in the above description and shown in the
accompanying drawings shall be interpreted as illustrative only of
particular embodiments and not limiting. Changes in detail or
structure may be made without departing from the basic elements of
the invention as defined in the following claims.
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