Note: Descriptions are shown in the official language in which they were submitted.
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PORTABLE PROGRAMMABLE HUMIDIFIER
Field of Invention
This invention relates to humidifiers, specifically to
humidifiers that can be used to control the relative humidity
inside a case used to store musical instruments or works of art.
Description of the Related Prior Art
Musical instruments and works of art are fragile objects that
require the proper levels of humidity. An improper relative
humidity level can cause warping, cracking, or shrinking of
wooden parts, varnishes, and paints. It is therefore desirable
to have a means to keep the relative humidity within a specific
range in storage containers when such objects are kept for
transport or storage.
Devices to accomplish the above object are numerous yet all
suffer from a number of drawbacks. Known devices, such as those
outlined in US Patent 4572051 and US Patent 5653920 suffer from
the drawback that the user cannot set a desired humidity level.
These two devices operate on the principle that the evaporation
of water and, hence, the provision of moisture into the air only
halts once the maximum moisture level within the container is
reached. Unfortunately, an excess of moisture can be as damaging
as the lack of the same.
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Another device, outlined in US Patent 4428892, discloses using a
control ring to control the evaporation rate of water. The
control ring adjusts the number and size of apertures through
which moisture is released. However, this device does not allow
for a self-regulating feedback mechanism in that the user must
constantly adjust and readjust the device to obtain the proper
desired relative humidity. Also, the device does not provide for
a means to display the desired relative humidity.
A further device, outlined in Canadian Patent 2053371,
accomplishes most of the above objectives. However, while
useful, it still suffers from a number of drawbacks. The device
uses a conventional DC electric motor to force moist air into the
instrument container. Unfortunately, conventional DC electric
motors use brushes that are in contact with the commutator of the
motor. This contact, and the very nature of conventional DC
motors, causes sparks that cause NOX to form. This material can,
with sufficient buildup, cause an acidic reaction in unvarnished
wood, alkyd based varnishes, and other materials and substances
that are part of musical instruments and other delicate objects.
This buildup of a harmful substance can easily occur in a sealed
environment, such as a closed instrument case or a closed storage
case for artwork. A further shortcoming of this device is its
reliance on batteries. While the device can run for up to 20
hours on a set of batteries, this time frame is, at best,
inconvenient, necessitating a user to keep replacing batteries.
Another shortcoming of this unit is the lack of a means to
visually determine the setting for the desired relative humidity.
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Summary of the Invention
The present invention serves to overcome the deficiencies
identified in the prior art. It is therefore the primary object
of the present invention to provide a portable humidifier that:
a) allows for controlling the desired relative humidity
setting
b) allows visual determination of the setting for the
desired relative humidity
c) allows for automatically regulating the relative
humidity of the instrument container
d) does not cause a buildup of harmful NOX gases within
the instrument container
e) does not necessitate frequent replacement of batteries
The above objects are achieved by providing a portable humidifier
for use in a container which houses objects requiring controlled
humidity, the humidifier comprising:
- a housing;
- a liquid reservoir contained within the housing;
- an evaporation surface in communication with the interior
of the reservoir;
- a humidification chamber containing the evaporation
surface and open to the container;
- a humidity sensing chamber open to the container;
- humidity sensing and control means in the sensing chamber;
- a moisture impenetrable wall between the humidity sensing
chamber and the humidification chamber;
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- air circulating means in fluid communication with the
evaporation surface, the circulating means comprising
- a brushless motor;
- a power supply in electrical connection with the
motor;
- a fan attached to the motor;
wherein the motor is controlled by the humidity sensing and
control means.
Preferably, the reservoir comprises a refillable tank means.
More preferably, the evaporation surface comprises a liquid
absorbent pad.
Most preferably, the power supply comprises a rechargeable
battery.
Conveniently, the power supply further comprises means to
recharge the rechargeable battery.
More conveniently, the power supply includes means to connect to
an AC power source.
Most conveniently, the humidity sensing and control means
comprises means to adjust a desired relative humidity setting,
means to display the desired relative humidity setting, means to
activate the motor if the desired relative humidity setting has
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not been reached, and means to shut off the motor if the desired
relative humidity setting is reached.
The advantages of the present invention are numerous. The
brushless motor does not produce sparks that cause NOX buildup.
The rechargeable battery removes the need to constantly replace
batteries. The means to connect to an AC power source removes
the need for batteries altogether, and the means to adjust the
desired relative humidity setting gives the user control over the
moisture level within the container. Furthermore, the device is
self-regulating in that the humidity sensing and control means
will automatically shut off power to the motor when the relative
humidity in the container is equal to the desired relative
humidity setting.
Brief Description of the Drawings
A better understanding of the invention will be obtained by
considering the detailed description below, with reference to the
following drawings in which:
Figure 1 is a perspective cut-away view of a portable humidifier
in accordance with the present invention.
Figure 2 is a side cut-away view of a portable humidifier in
accordance with the present invention.
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Figure 3 is a circuit diagram of the battery recharging circuit
in accordance with the present invention.
Figure 4 is a circuit diagram of the motor control circuit in
accordance with the present invention.
Figure 5 is a circuit diagram of part of the power supply circuit
in accordance with the present invention.
Figure 6 is a circuit diagram of the logic control circuit in
accordance with the present invention.
Detailed Description of the Invention
Referring to Figures 1 and 2, a portable humidifier 10 in
accordance with the present invention is disclosed.
Humidification chamber 40 is separated from the humidification
sensing chamber 50 by the air intake chamber 45.
The humidification chamber 40 contains the liquid reservoir 20.
On top of the liquid reservoir 20 is the evaporation surface 30.
The evaporation surface 30 is in communication with the liquid
reservoir 20 by means of a wick 25 which is partly disposed
within the liquid reservoir 20. The liquid reservoir 20 can be
refilled through refill hole 29. To prevent leakage or spillage,
stopper 27, utilizing an elastomer seal preferably in combination
with a screw mechanism, seals the refill hole 29. Adjacent to
the evaporation surface 30 are humidity exit ports 32. Through
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these ports 32, humidified air is circulated into the
surrounding air.
The evaporation surface 30 can be constructed out of a liquid
absorbent pad. A pad composed of a flax material has been shown
to effectively retain liquid while dispensing the desired amount
of moisture. A further refinement can be made by attaching a
piece of chamois cloth to the pad, thereby increasing the liquid
retention capabilities of the pad and not decreasing its moisture
dispensing qualities.
Mounted between the humidification chamber 40 and the air intake
chamber 45 is the fan 90 having a brushless motor 92.
Preferably, well-known CPU fans, normally utilized to cool
computer processors, can be used. This type of fan has a
number of distinct advantages. Specifically, these fans use a
brushless motor that do not have brushes in contact with a
commutator. Such a design eliminates sparks produced by the
brushes short circuiting different sections of the commutator.
The elimination of these sparks reduces the risk of NOX build up
in the air. Another advantage of this type of motor is its
compactness. This type of design is about 66% longitudinally
shorter than comparable conventional electric motors.
The air intake chamber 45 has a number of air intake ports 47
through which the fan 90 can draw in air from the outside. The
only communication that the air intake chamber 45 has with the
humidification chamber 40 is through the fan 90. On the other
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side of the air intake chamber 45, opposite the fan 90 and the
humidification chamber 40, is a moisture impenetrable wall 49
separating the humidity sensing chamber 50 from the
humidification chamber 40 and the air intake chamber 45.
The humidity sensing chamber 50 contains the electronics and the
power supply of the humidifier 10. The humidity sensor 70 is
adjacent a number of humidity intake ports 55. The circuit board
60 contains the circuitry to control both the fan 90 and the
power supply.
Programmability of the humidity sensor 70 is built into the
circuit board 60. The board 60 is connected to a humidity
setting switch 80. Through this switch 80, the user can adjust
the desired relative humidity. Also connected to the circuit
board 60 is an LCD (liquid crystal display) 65 that displays the
desired relative humidity setting. When the user adjusts the
desired relative humidity setting through the switch 80, the LCD
display 65 displays the desired relative humidity. It must be
noted that, preferably, the humidity setting switch 80 is of a
rocker type switch such that depressing one side of the switch
increases the desired relative humidity and depressing the other
side of the switch decreases the desired relative humidity. It
would also be preferable that the humidity setting switch be used
as an on-off switch for the humidifier 10.
The power supply for the humidifier 10 can be from two sources:
batteries or direct wall current. The battery receptacle 100
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holds the batteries for the device. There is provided an AC
adapter jack 102 through which, in conjunction with an AC
adapter, the device can be powered by direct wall current. It
would also be preferable that the batteries 104, located in the
battery receptacle 100, be of the rechargeable type. Such
batteries, commonly used in cordless telephones, can be easily
recharged while the humidifier 10 is connected to a wall current.
The workings of the humidifier 10 can now be described. The
humidifier 10 is turned on through the humidity setting switch 80
that doubles as a power switch. The power can be harnessed from
either the batteries 104 or through the AC adaptor jack 102 in
conjunction with an AC adaptor connected to a wall current. The
user sets the desired relative humidity setting through the
humidity setting switch 80, noting that the LCD display 65 shows
the desired setting. Once the humidifier 10 has been turned on,
the humidity sensor 70 senses the relative humidity of the air
that enter through the humidity intake ports 55. If the logic
control circuitry determines that the set relative humidity does
not correspond with the relative humidity read by the humidity
sensor 70, a signal is sent to the fan 90 activating it. If, on
the other hand, the logic control circuitry determines that the
sensed relative humidity corresponds to the desired relative
humidity setting, the signal sent to the fan 90 turns it off .
The workings of the logic control circuit will be examined below.
The humidity of the surrounding air is adjusted thus: air from
the surroundings enters the air intake chamber 45 through the air
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intake ports 47 and, if the fan 90 is on, is blown to the
evaporation surface 30. The evaporation surface 30, being moist
due to communication with the liquid reservoir 20 through the
wick 25, releases moisture to the air blown on to it by the fan
90. The air, now moist due to being in contact with the
evaporation surface 30, exits the humidification chamber 40
through the humidity exit ports 32. The relative humidity is
then sensed through the now humid air entering the humidity
sensing chamber 50 through the humidity intake ports 55. The
humidity readings are prevented from being corrupted by the
presence of the moisture impenetrable wall 49 disposed between
the humidity sensing chamber and the other two chambers. Thus,
humidity only enters the humidity sensing chamber 50 through the
humidity intake ports 55.
Referring to Figures 3, 4, and 5, the workings of the power
supply and the logic control circuitry will now be examined. The
reference numerals on Figures 3-6 refer, preferably, to the
following components with the following values:
Resistors Value (S2)
Rl 240
R2 1K
R3 100
R4a 6R8
R4b 6R8
R5 lOK
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R6 lOK
R7 lOK
R8 lOK
R9 1K
R10 5600
R11 100
R12 470
R13 lOK
R14 lOK
R15 560
R16 lOK
R17 4K7
R18 16K
R19 13K
R20 100K
R21 lOK
Capacitors Value (F)
C1 0.01 uF
C2 10 uF
C3 0.1 uF
C4 0.01 uF
C5 0.1 uF
C6 4.7 uF
C7 4.7 uF
C8 4.7 uF
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C9 39 pF
C10 39 pF
C11 0.1 uF
Semiconductors Type/Maaufacturer/Part number
U1 Positive Output Voltage
Regulator/ National/ LM317T
U2 Low Dropout Linear Regulator
/
Toko Inc. / TK 112-40 CT
U3 Quad Low Voltage CMOS
Operational Amplifier/
National Semiconductor / LMC
6584 BIM
U4 Programmable Microcontroller
/
Microchip Semiconductor /
PIC16LC72 (having 2K x 14
words of program memory)
U5 Microperipheral / Microchip
Semiconductor / MCP130
HS1 Humidity Sensor / Honeywell /
HIH-3605-B
D1 Diode / DL 4003 MSCT
D2 Diode / DL 4003 MSCT
D3 Diode / DL 4148 MSCT
D4 Diode / DL 4148 MSCT
DB1 DF O1S [lA/100 v PIV]
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Q1 Transistor / 2N2222A
Q2 Transistor / 2N3904
F1 Polyswitch self-resetting fuse
/ Raychem / RXE 020
M1 Miniature LV fan nominal 5 VDC
75 mA / Panasonic / UDQFB3E5-1
LED1 high efficiency LED (red)
LCD1 2 digit x 7 segment LCD /
Varitronix / VI-201-2
X1 32.768 kHz cyl. crystal C-OO1R
/ Epson / SE 3201
PB1 (U) 9.5 mm push-button, normally
PB2(D) open switch / Panasonic / EVQ-
PB3(A) 11 L 09 K
Referring to Figure 3, the battery recharge circuit is shown.
The AC power source is connected through C1. This AC current is
passed through DB1 and converted to DC and then fed into U1, a
voltage regulator that outputs about 5VDC. Power thus comes from
either the batteries or U1 and into the V++ symbol. From here,
power is fed into U2, a linear regulator that outputs a clean
4.OVDC signal, at V+, that powers the other components. (See
Figure 5)
Referring to Figures 4 and 6, the logic control circuitry will
now be examined. The microcontroller U4 controls the LCD
display LCD1 along with the motor M1. The microcontroller U4 is
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preprogrammed to receive input from the switches U and D.
Depressing switch U increases the desired relative humidity
setting while depressing D does the opposite. The
microcontroller U4 determines whether the analog input from HS1,
the humidity sensor, is within the set desired relative humidity
range. This is easily accomplished as the microcontroller U4 has
a number of integrated A/D converters. If the relative humidity
is within the set desired range, then the motor M1 is not
activated. If not, a signal is sent through RC2 and M1 is
thereby activated.
It must be noted that the complete workings of the
microcontroller U4 and the other components are well known in the
art. The supporting circuitry, such as the operational
amplifiers contained in U3, the crystal X1, and the
microperipheral U5, serve to support the functioning of the
microcontroller U4. The exact logic that is followed by the
microcontroller will be determined by the program entered into
the microcontroller.
Also of interest is the fact that the circuit has a number of
fail-safe mechanisms to protect against short circuits or over
current situations. The fuse F1 prevents any anomalous
conditions from damaging the internal circuitry. Also, the use
of the linear regulator U2 provides further protecting as the
component selected will automatically shutdown if it senses a
short circuit or an over current condition at V+.
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A further possible refinement would be the inclusion of a D/A
converter between the microcontroller U4 and the motor M1. Such
a refinement would provide even more control of the motor M1 by
controlling the voltage being fed into motor M1. This would
control the speed of the motor M1 and thereby the rate that the
relative humidity is adjusted.
A person understanding this invention may now conceive of
alternative structures and embodiments or variations of the above
all of which are intended to fall within the scope of the
invention as defined in the claims that follow.
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