U.S. patent application number 10/523113 was filed with the patent office on 2006-05-04 for personal care device with thermal feedback and operating conditions display.
Invention is credited to Wing Kin Chan.
Application Number | 20060093337 10/523113 |
Document ID | / |
Family ID | 31198387 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060093337 |
Kind Code |
A1 |
Chan; Wing Kin |
May 4, 2006 |
Personal care device with thermal feedback and operating conditions
display
Abstract
A personal care device such as a hair dryer with thermal
feedback sensor near the air-outlet for automatic heating power
reduction when a pre-determined threshold temperature has reached.
The device further includes graphical and numerical displays
indicating its operating conditions.
Inventors: |
Chan; Wing Kin; (Hong Kong,
CN) |
Correspondence
Address: |
BUCHANAN INGERSOLL PC;(INCLUDING BURNS, DOANE, SWECKER & MATHIS)
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
31198387 |
Appl. No.: |
10/523113 |
Filed: |
August 1, 2003 |
PCT Filed: |
August 1, 2003 |
PCT NO: |
PCT/IB03/03080 |
371 Date: |
September 13, 2005 |
Current U.S.
Class: |
392/385 |
Current CPC
Class: |
A45D 20/30 20130101;
A45D 20/10 20130101 |
Class at
Publication: |
392/385 |
International
Class: |
A45D 20/10 20060101
A45D020/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2002 |
CN |
02105673.1 |
Claims
1. A personal care device such as a hair dryer or a fan-heater
including a main housing, a motor, a motor driven fan, a heating
element, controlling means, a thermal sensor, said main housing
defines an air-passageway having an air-inlet and an air-outlet,
said heating element is disposed intermediate between said
air-inlet and said air-outlet, said thermal sensor is disposed
adjacent to said air-outlet and provides temperature information to
said controller, said controlling means includes memory for storing
temperature information and said controlling means includes means
for comparing said temperature information received from said
thermal sensor with the pre-stored temperature information, said
controlling means causes said heating element to reduce heating
power output according to a pre-determined manner when the received
temperature information corresponds to a temperature which exceeds
a pre-determined threshold.
2. A device of claim 1, wherein said thermal sensor includes a
negative temperature coefficient ("NTC") device.
3. A device of claim 1, wherein said pre-determined manner includes
a plurality of pre-determined settings corresponding to a plurality
of pre-determined discrete heating power and fan speed
settings.
4. A device of claim 1, further including display means on said
main housing indicating the instantaneous operating conditions of
said device.
5. A device of claim 4, said display means includes graphical
representations showing operating conditions of said device
including fan speed level and triggering of ionizer for hair.
6. A device of claim 4, said display means includes numerical
display showing the instantaneous power of said heater.
7. A device of claim 6, wherein said display further includes
graphical representations showing operating conditions of said
device including fan speed level and triggering of ionizer for
hair.
8. A device according to claim 4, said display include a LCD
display screen.
9. A device according to claim 5, said display include a LCD
display screen.
10. A device according to claim 6, said display include a LCD
display screen.
11. A device according to claim 7, said display include a LCD
display screen.
Description
FIELD OF INVENTION
[0001] The present invention relates to personal care devices and,
more particularly, to personal care devices provided with heating
elements and a motor driven fan. This invention also relates to
hair care devices with a liquid crystal display (LCD) device. More
specifically, although of course not solely limiting thereto, this
invention relates to hair dryers and fan heaters with
over-temperature protection and operating conditions display.
BACKGROUND OF THE INVENTION
[0002] Personal care devices with heating elements and a motor
driven fan are generally used to enhance personal comfort or
personal grooming.
[0003] For example, a hair care device such as a hair dryer or a
hair curler with a heater and a motor driven fan provides a
convenient and localized heating source with forced air circulation
so that warm air can be delivered for hair care and styling within
a short time. In such applications, a wide range of heating power
level variation and fan-speeds is usually required in order to meet
with the specific personal comfort or grooming requirements. For
example, a high heating power level with a high fan-speed may be
required to blow dry and style wet hair while a low or moderate
heating level and a moderate fan-speed may be required for gentle
hair styling.
[0004] Similarly, in the case of fan-heaters, a high heating power
and a high fan-speed will be required to expeditiously warm up a
cold space while a moderate or a low heating level and fan-speed
may be required to maintain a room at a relatively comfortable
temperature and humidity.
[0005] To accommodate such a wide range of operating power
requirements, heating elements provided in such personal care
devices must be able to operate on a wide range of power output.
The typical operating power ratings of such heating elements are
usually in the region of a few hundred Watts to a maximum of
2,000-3,000 Watts.
[0006] Personal care devices of this type usually include a main
housing defining an air-passageway having an air-inlet and
air-outlet. The heating element is generally disposed intermediate
between the air-inlet and the air-outlet so that the downstream air
will be warmed or heated up before leaving the device for hair
styling or other appropriate applications. These personal care
devices are usually provided with user control interfacing means
such as a control knob or a rocker switch with a plurality of
heating level and fan-speed settings. The heating level setting is
usually graduated with discrete levels and calibrated on the
assumption that air will pass through the air-passageway
unobstructed. Under such an assumption the heated air exiting from
the nozzle or air-outlet at a pre-determined setting will be at a
reasonably constant, usable, and safe temperature. However, this is
not always the case and the temperature of the heating element can
be substantially elevated when the exit air passageway is blocked,
for example, when the air-outlet or nozzle is placed too close near
the head of the user or other blocking surfaces. This undesirable
obstruction of airflow through the passageway adversely increases
the temperature of the heating element because of insufficient
ventilation and may result in personal injuries as well as fire
hazards. Hence, it will be desirable if an improved safety
protection means can be provided to such personal care devices to
alleviate or avoid risks of personal injuries of fire hazards
associated with the use of such devices.
[0007] Furthermore, while such personal care devices are provided
with user selectable switches graduated with discrete levels for
setting the operating conditions, such controlling knobs are
usually in the form of rocker switches which do not provide the
user with any useful and indicative operating information. Hence,
it will be desirable if useful information can be conveyed to the
user by means of an improved scheme and by way of improved
means.
OBJECT OF THE INVENTION
[0008] Accordingly, it is an object of the present invention to
provide personal care devices such as hair dryers, hair blowers,
hair curlers and fan-heaters with safety and protective means are
provided to alleviate the risk of personal injuries or fire hazards
due to over-temperature resulting from adverse or inappropriate
operation conditions of the devices.
[0009] It is another object of the present invention to provide
improved personal care devices with schemes and means for visually
conveying the operating conditions of the device to the user to
facilitate enhanced interactive operation between the user and the
device. As a minimum, it is an object of the present invention to
provide improved personal care devices such as hair dryers, hair
blowers, air curlers and fan-heaters as an alternative choice to
the general public.
SUMMARY OF THE INVENTION
[0010] According to a first aspect of the present invention, there
is provided a personal care device such as a hair dryer or a
fan-heater including a main housing, a motor, a motor driven fan, a
heating element, controlling means, a thermal sensor, said main
housing defines an air-passageway having an air-inlet and an
air-outlet, said heating element is disposed intermediate between
said air-inlet and said air-outlet, said thermal sensor is disposed
adjacent to said air-outlet and provides temperature information to
said controller, said controlling means includes memory for storing
temperature information and said controlling means includes means
for comparing said temperature information received from said
thermal sensor with the pre-stored temperature information, said
controlling means causes said heating element to reduce heating
power output according to a pre-determined manner when the received
temperature information corresponds to a temperature which exceeds
a pre-determined threshold.
[0011] According to a second aspect of the present invention, there
is provided a personal care device such as a hair dryer, a hair
blower, a hair curler and a fan-heater having display means on said
main housing indicating the instantaneous operating conditions of
said device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] A preferred embodiment of the present invention will be
explained below by way of example and with reference to the
accompanying drawings, in which:
[0013] FIG. 1 is a hybrid circuit and block diagram showing the
general circuit arrangements of a preferred embodiment of a hair
dryer with a frontend sensing circuit connected to a
micro-controller for automatic feedback control of the heating
power output of the hair dryer,
[0014] FIG. 2 is a schematic circuit diagram showing an example of
a general and more detailed circuit arrangement of the hair dryer
of FIG. 1,
[0015] FIG. 3 is a schematic circuit diagram showing the general
circuit arrangement of a second preferred embodiment of a hair
dryer of the present invention including a first embodiment of
electronic display means indicating the operating conditions of the
hair dryer,
[0016] FIG. 4 shows a series of display variations as an example of
suitable screen displays for use with the arrangement of FIG.
3,
[0017] FIG. 5 is a general circuit diagram showing another
preferred embodiment of a control and display arrangement for the
hair dryer of FIG. 1,
[0018] FIG. 6 shows an example of a series of graphical display
layouts compatible with the display means shown in FIG. 5, and
[0019] FIG. 7 is a partially exploded view of a hair dryer
illustrating the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Referring firstly to the hybrid circuit and block diagram of
FIG. 1 and the partially exploded drawing of FIG. 7, there is shown
an application in which a thermal sensing means is utilized for
automatic thermal feedback to control the operation of the heating
elements of a hair dryer 10 as an example. The circuit arrangement
includes a thermal sensing frontend circuitry 100, a
synchronization circuitry 110 for synchronizing with the
alternating current supply to which the hair dryer is connected,
controlling means 120 which is a micro-controller unit ("MCU") in
the present example, a first heating element 130 and a second
heating element 140 which are connected in parallel and
individually switchable. It will become apparent from the
description below that the output heating power of the hair dryer
can be flexibly and sophistically varied by selective turning on
the individual heaters during different times of the cycles of the
alternating current power supply.
[0021] Broadly speaking, a thermal sensing means, which is a
negative temperature coefficient ("NTC") device 101 in this
embodiment, is disposed at a convenient position to detect the
instantaneous operational temperature of the hair dryer 10. The
output of the thermal sensing means is connected to an input port
of the micro-controller unit 120 to provide the MCU with the sensed
temperature information for appropriate action. The thermal sensing
element, i.e., the NTC element in the present embodiment, is
connected to a biasing circuit so that the change in the electrical
characteristics of the NTC member can be transformed into an
electrical signal usable by the MCU 120.
[0022] In this specific example, the NTC device is connected to a
supply voltage rail (VCC). The other end of the NTC is connected to
the ground via a resistor (R in FIG. 1). The output node of the NTC
device, which is the node interconnecting the NTC device and the
resistor R, is fed into an input port of the MCU. A capacitive
means (C in FIG. 1) is connected across the resistor R as a
delaying buffer to prevent over-sensitiveness to changes in the
ambient temperature or transient interference. As the NTC member
101 is essentially a resistor with decreasing resistance on
increasing temperature, an increase in temperature on the NTC
device will result in a decrease in the resistive value.
Consequently, an increase in the output voltage will be detected at
the output node of the NTC device. This phenomenon provides useful
control information to the MCU in determining the instantaneous
downstream air temperature.
[0023] With prior calibration or tabulation of the electrical
characteristics of the NTC member 101, for example, the resistance
and temperature correlation of the NTC member, the relationship
between the output voltage and the detected temperature can be
readily determined by the MCU and utilized to prevent over-heating
of the hair dryer. For example, information concerning the maximum
temperature threshold, and the corresponding voltage output from
the NTC output node, corresponding to a specific heating power and
fan-speed setting of the hair dryer can be stored in a memory means
accessible to the MCU. Once the NTC device output voltage indicates
a temperature exceeding the temperature threshold, the
micro-controller will send an instruction to the controlling
circuitry to reduce or even turn off the heating output.
[0024] In the present specific embodiment, non-dissipative heating
power output control scheme is utilized as a convenient preferred
example. In this scheme, reduction in heating output is achieved by
selectively activating a first heating element and/or a second
heating element which are individually switchable during certain
portion of the alternating current power supply. A parallel
combination of two individually switchable heating elements is used
in the present embodiment so that a more versatile, flexible and
sophisticated heating output variation scheme can be provided.
[0025] For example, when the two heating elements are continuously
turned on during the whole period of the alternating current
supply, the heating power output level will be at the maximum.
Reduction in heating output can be obtained by selectively turning
on or off one or both of the heaters during a certain period of the
alternating current supply. For example, heating power output can
be reduced by actuating the first heating element during the
positive half-cycles of the alternating current supply while the
second heating element can be turned off only during the negative
half-cycles of the power supply. Of course, the first and second
heating elements can be selectively turned on during many possible
combination of actuation timing with reference to the alternating
current supply cycles to achieve an overall reduced power
output.
[0026] In order to reduce adverse harmonics due to selective
actuation of the first and the second heating elements, it is
desirable that the level of power consumption during the whole
period of the alternating current supply is as even as possible
since it has been observed that stronger harmonics will be
generated if the technique of power chopping is utilized which will
result in large power consumption differences or discontinuity
during the alternating current supply cycles. Hence, it will be
desirable to actuate the heating elements evenly throughout the
cycles of the alternating current supplies. To fulfil this purpose,
a synchronization circuit 110 with an input connecting to the
alternating current supply and an output connected to the MCU 120
is provided. This synchronization circuit provides timing
information of the alternating current supply so that the MCU can
determine the appropriate actuation timing of the heating elements
at or near zero-crossing point of the alternating current supply or
other appropriate points to reduce harmonics and alleviate other
undesirable effects. In this preferred embodiment, triacs are used
and the synchronization circuit provides useful firing and time
information to actuate the triacs.
[0027] In the present specific embodiment, power reduction by
selectively power chopping or selectively turning on and off the
heating elements at appropriate times provides a non-dissipative
scheme of power reduction and the heating element actuation timing
control is important to reduce adverse harmonics. Of course,
dissipative schemes of heating power reduction can also be used. In
dissipative heating power reduction schemes, a dissipative element,
such as a load resistor, is generally connected in series with a
heating element or a combination of heating elements so that the
extra or redundant electrical energy is wasted through the
dissipative element. As the problem of adverse harmonics is not
usually critical in such dissipative schemes, less stringent
heating element actuation timing schemes are required and the
synchronization circuitry may not be required.
[0028] Referring to FIG. 2, a more detailed circuitry diagram
embodying the circuitry of FIG. 1 is shown. It will be noted that
the thermal sensing circuitry 100, the first 130 and the second 140
heating elements and the synchronization circuitry 110 are
connected to the MCU 120. In addition, user controlling interfacing
means, including a fan-speed setting knob 150 and a heating level
selecting knob 160, is also provided. Furthermore, display means
170 indicating the operating conditions of the hair dryer are
connected to the output ports of the MCU 120 so that the
appropriate operating conditions can be transmitted from the MCU
for showing on the display means. A direct current (DC) motor 180
is provided to provide forced air movement for delivering air from
the hair dryer and a rectifying bridge is provided to generate the
necessary direct current supply. An additional set of heating
element 190 is further provided between the alternating current
supply and the rectifying bridge to accommodate or absorb the
voltage supply differences between the rated input voltage of the
rectifier and the output of the alternating current supply.
[0029] Turning now to the operation of the hair dryer by referring
to the hair dryer of FIG. 7, it will be noted that the hair dryer
10 includes a main housing 11 having a barrel 12 and a handle 13. A
first heating element 130, a second heating element 140, a motor
and a motor driven fan 181 are generally disposed inside the barrel
12. For user convenience, the user controlling interfacing means
including the fan-speed control knob and the heating level setting
knob are preferably disposed on the outside of the handle portion.
The barrel defines an up-stream air-inlet 14 near the handle
portion and a downstream air-outlet 15 at the other end. The
heating elements are preferably disposed intermediate between the
air-inlet 14 and the air-outlet 15. The thermal sensing means, or
the NTC element 101 in the present embodiment, is disposed near the
air-outlet 15 since, under normal operation, the exiting air will
have an elevated temperature and the temperature at this position
will build up rapidly if adverse operating conditions are
encountered. When the heating power control knob is set a
pre-determined level with a pre-determined fan-speed, the warn air
exiting from the air-outlet would not normally exceed the
temperature threshold under normal operation. Such a temperature
threshold can usually be represented by an electrical parameter
characteristic of the thermal sensing circuit. In the present
embodiment, this temperature threshold is represented by the
maximum voltage output at the NTC output node 102.
[0030] When the warm- or hot-air generating hair dryer is pushed
towards a blocking surface, the temperature of the heating elements
will be elevated as a result of insufficient air ventilation or
insufficient radiation. Continued blocking may cause the heating
element to become red hot and cause personal injuries and fire
hazards. In the present embodiment, the micro-controller 120 will
appropriately reduce the heating output to alleviate such risks and
hazards upon detection of a signal indicating over-temperature. The
normal heating output may be resumed, if on a subsequent MCU check,
the thermal sensor output voltage is restored to a safe level. As
explained before, the heating power output can be reduced by
dissipative or non-dissipative schemes although non-dissipative
schemes are preferred for the preservation of energy and
environmental protection. Of course this thermal feedback control
topology can be utilized in both the dissipative and
non-dissipative schemes.
[0031] Referring to FIG. 3 in which a second control and display
circuitry of a preferred embodiment of the hair dryer is shown, the
hair dryer circuit includes a motor 280 with a parallelly connected
switchable shunt resistor controllable by the switch SW2 250 for
speed variation and a switchable ionising circuitry providing
ionised warm air to the hair for styling. In addition, a heater
level control switch 260 SW1 switchable to a plurality of discrete
heating power level settings are also shown. The operating
conditions of the switch SW2 280, the ionising circuit 261, and the
heating level SW1 switch are connected to the input ports of a MCU.
The output of the MCU is connected to a display means 270 for
displaying the operating conditions of the hair dryer.
[0032] For example, when the shunting switch SW2 250 is closed,
corresponding to a lower motor speed, the terminal of SW2 will be
pulled high and the input port PB3 of the MCU 220 will detect a low
signal because of the inverted circuit connected between the input
port PB3 and the switch SW2 250. Similarly, the MCU 220 can detect
whether the ionising circuitry is in operation by detecting whether
the serial switch "IONIC SW" 262 is closed or opened. When IONIC SW
262 is closed, this terminal is at a high potential and the input
port PB4 of the MCU 220 will detect a low signal. Similarly, when
the heating power level selector switch SW1 260 is set to the
"high" setting corresponding to a high power output, the input port
PB1 of the MCU 220 will detect a low signal while the other input
port PB0 will remain high. On the other hand, when the switch SW1
260 is set to the "low" setting, the input at PB0 of the MCU will
be pulled low and the input port PB1 will remain high. Thus, by
scanning the conditions of the input ports PB0 and PB1, the MCU can
decide the instantaneous heating power level setting and transmit
information concerning the operating condition to the display
means. The display means can be, for example, a LCD or other
appropriate displays, includes a plurality of input nodes for
connecting to the output nodes of the MCU.
[0033] By appropriate configuration or programming of the MCU, the
operating conditions or parameters of the hair dryer as detected
and monitored at the various input ports of the MCU will be
converted into the corresponding control signals at the output
ports for showing on the display means. The display samples shown
in FIG. 4 represent a series of possible information display which
can be shown on the display means for reflecting the operating
conditions of the hair dryer.
[0034] For example, this preferred hair dryer has two speed
settings and two heating power level settings with an additional
"cool shot" for blowing only cool air, making a total of five
different combination settings. The operating conditions of the
hair dryer can then be shown in the display means.
[0035] In the preferred example of the display means and referring
to the left-most column of the graphical displays, the first row of
display corresponds to the operating setting number with the range
of 1 to 5, the second row indicates the present heating power level
setting in numerical form showing the wattage and the third row
indicates whether the negative iron emission circuitry is in
operation. On the right side, an 8-bar indicator is provided to
indicate the temperature of the air exiting from the hair dryer.
Usually, more lit bars will mean a higher temperature and when all
the 8 bars are lit, it means the hair dryer is operating at its
highest operating temperature.
[0036] Referring to the second column of graphical representations
of FIG. 4, in this configuration, most of the display variations
have the same meaning as that above except that the 8-level bar
indicator is now used to indicate the fan-speed of the hair dryer.
As there are only two power settings, the 8-level bar indicator is
split into two display regions comprising 4 bars each. When the
hair dryer is operating at the high fan-speed, all the 8 bar levels
are lit. On the other hand, when the hair dryer is operating at a
low fan-speed, only the four lower bars are lit. Thus, it will be
appreciated that the display means can be flexibly arranged to
provide the desirable information for the benefit of the consumers.
In addition to the functional parameters to be displayed, other
information, for example, the trade mark, logo, or other
proprietary signs 500 of the manufacturer can also be displayed on
the same display means or on the main housing of the hair dryer
whether by LCD, LED or other appropriate display means.
[0037] Referring to FIGS. 5 and 6, there is shown a hair dryer with
a second preferred embodiment of control and display means 370. In
this hair dryer, the usual essential features of hair dryers are
similarly provided and will not be discussed in detail. This hair
dryer includes a plurality of progressive or gradual control
switches SW1-SW6 separating into three groups, namely, SW1 and SW2,
SW3 and SW4, SW5 and SW6. For example, the switches 360 SW1 and SW2
correspond to the heating element control, SW3 and SW4 350
correspond to the fan-speed control and SW5-SW6 361 correspond to
the ionizer control. When SW1 is pressed, the MCU will
progressively increase the heating power output until SW1 is
released. On the other hand, when SW2 is depressed, the MCU will
control the heating elements to reduce the heating power output
until SW2 is released. When neither SW1 nor SW2 is depressed, the
hair dryer will continue operating in its present state. Likewise,
when SW3 is depressed, the MCU will increase the fan-speed until
SW3 is released or when maximum speed has been reached. Similarly,
when SW4 is depressed, the MCU will cause the fan-speed to decrease
until the motor stops or until the switch is released. The ionising
control switches SW5 and SW6 work generally under the same
principles.
[0038] In this preferred example, the possible depression of the
control switches is by the formation of a matrix comprising the
input ports 20-24 of the MCU with port 20 corresponding to the
control of the heating element, port 21 corresponding to the
fan-speed control and port 22 corresponding specifically to the
ionizers control. Similarly, port 24 of the MCU corresponds to an
indication of upward adjustment and port 23 indicates downward
adjustments. Of course, other arrangements are as possible. By
using a matrix form of combination control, a user's request for
change of operating conditions can be constantly monitored and
entertained. In this preferred embodiment, a different form of
display is provided. The display in the present embodiment includes
a LCD display means with the speed and temperature presented in two
separate bar-indicators plus an ionizer triggering sign. By
connecting the LCD display means to the MCU, the speed and
temperature display bars can provide a multi-level indicator
corresponding to the signal provided by the MCU corresponding to
the detected operating conditions.
[0039] The three columns of display shown in FIG. 6 shows some
possible variations of the LCD information displays arrayed in
column order speed, temperature and ionising indication.
[0040] While the present invention has been explained by reference
to the preferred embodiments described above, it will be
appreciated that the embodiments are only examples provided to
illustrate the present invention and are not meant to be
restrictive on the scope and spirit of the present invention. This
invention should be determined from the general principles and
spirit of the invention as described above. In particular,
variations or modifications which are obvious or trivial to persons
skilled in the art, as well as improvements made on the basis of
the present invention, should be considered as falling within the
scope and boundary of the present invention. Furthermore, while the
present invention has been explained by reference to a hair dryer
with non-dissipative power reduction scheme, it should be
appreciated that the invention can apply, whether with or without
modification, to other hair dryers and fan heaters irrespective of
the mode of power reduction schemes.
* * * * *