U.S. patent application number 09/827039 was filed with the patent office on 2001-11-01 for charge transfer capacitance sensing and control system for an integrated venting system.
Invention is credited to Cardwell, Casey, Cardwell, Cory, Cardwell, Troy.
Application Number | 20010034899 09/827039 |
Document ID | / |
Family ID | 26890958 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010034899 |
Kind Code |
A1 |
Cardwell, Troy ; et
al. |
November 1, 2001 |
Charge transfer capacitance sensing and control system for an
integrated venting system
Abstract
A capacitance charge transfer sensing and control system for a
venting system. Preferably the sensing and control system is used
with a toilet having an integrated venting system which includes
ducting communicating with an exhaust air passageway located in the
toilet bowl and an exhaust fan to draw air from the bowl and
exhaust it outside. A sensing electrode, such as a wire antenna, is
located in a covered location adjacent the toilet bowl, preferably
in the exhaust air passageway located in the bowl of an integrated
toilet venting system. The wire antenna is connected to a detection
and motor control circuit which can detect a change in capacitance
of the wire antenna upon a person entering into close proximity
thereto. A micro-controller in the detection and motor control
circuit is programmed to generate a circuit closing signal to an
electric switch located in the circuit between a power source and
the exhaust fan in response to a minimum pre-selected increase in
the capacitance of the wire antenna. The micro-controller is
programmed to open the circuit between the power source and the
exhaust fan when there is a pre-selected decrease in the
capacitance of the wire antenna and a pre-selected period of time
has elapsed after such decrease.
Inventors: |
Cardwell, Troy; (Eugene,
OR) ; Cardwell, Casey; (Eugene, OR) ;
Cardwell, Cory; (Eugene, OR) |
Correspondence
Address: |
Robert E. Howard
P.O. Box 10345
Eugene
OR
97440
US
|
Family ID: |
26890958 |
Appl. No.: |
09/827039 |
Filed: |
April 4, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60195398 |
Apr 7, 2000 |
|
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|
Current U.S.
Class: |
4/216 |
Current CPC
Class: |
E03D 9/05 20130101 |
Class at
Publication: |
4/216 |
International
Class: |
E03D 009/04 |
Claims
The invention claimed is:
1. A toilet having a base, a bowl, and an air exhaust system for
removing air from the vicinity of said bowl and exhausting it in a
region remote from said bowl, said air exhaust system including
ductwork communicating said bowl and said region remote from said
bowl and an electric exhaust fan motor connected to a power source
through a switch means, said exhaust fan motor adapted to drive an
exhaust fan in communication with said ductwork; a sensing
electrode located in close proximity to said bowl; and a detection
and motor control circuit in electrical communication with said
switch means and with said sensing electrode, said detection and
motor control circuit adapted to charge said sensing electrode and
to detect changes in the capacitance of said sensing electrode;
said detection and motor control circuit adapted to generate an
actuating signal to said switch means upon detection that the
capacitance of said sensing electrode has increased to a minimum
triggering level, thereby opening electrical communication between
said power source and said electric exhaust fan motor; said
detection and motor control circuit adapted to close electrical
communication between said power source and said electric exhaust
fan motor when said minimum triggering level of capacitance of said
sensing electrode is not present.
2. The device of claim 1 wherein said air exhaust system includes
an exhaust air duct integral with said bowl, said sensing electrode
being located within said exhaust air duct.
3. The device of claim 2 wherein said sensing electrode is a
conductive, non-magnetic wire antenna.
4. The device of claim 3 wherein said sensing electrode is copper
wire.
5. The device of claim 2 wherein said sensing electrode extends
partially around said exhaust air duct.
6. The device of claim 1 wherein said power source is a DC power
source.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Serial No. 60/195,398, filed Apr. 7, 2000.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a sensor and control system for
actuating the exhaust fan of a ventilation system. In particular,
the invention relates to a sensor and control system for actuating
the exhaust fan of an integrated toilet exhaust system.
[0003] Many toilet exhaust systems have been proposed. Some are
retrofit systems and some are "integrated" systems, i.e.,
substantially formed as part of the toilet during manufacture. An
example of the integrated type of toilet exhaust system is
described in U.S. Pat. No. 6,019,862.
[0004] Some of these systems use manual exhaust fan actuation
means, such as a wall switch.
[0005] Some systems use pressure plate type switches located
between the upper rim of the toilet and the toilet seat which
complete the circuit to the exhaust fan upon someone sitting on the
toilet seat and open the circuit when the person gets off the seat.
This is the type of activation means disclosed in U.S. Pat. No.
6,019,862, which refers to U.S. Pat. No. 5,253,371 for a more
complete description.
[0006] The manual actuation means suffers from the problem of
people forgetting to turn the switch on at the time they sit down
on the toilet or forgetting to turn it off after completing their
use of the toilet.
[0007] The pressure plate type actuation means is at least
automatic, but suffers from soiling and frequent breakdown.
SUMMARY OF THE PRESENT INVENTION
[0008] It is an object of the present invention to provide
automatic means for actuating a toilet exhaust system.
[0009] It is a further object of the present invention to provide a
toilet exhaust actuation means that has no moving parts, which
eliminates or reduces maintenance problems.
[0010] It is a still further object of the present invention to
provide a toilet exhaust actuation means that senses the presence
of a person before that person commences use of the toilet to
actuate the toilet exhaust system and senses the absence of that
person after toilet use is finished to deactivate the toilet
exhaust system after an appropriate period of time has passed.
[0011] These and other objects are achieved by the device of the
present invention. The device includes a sensing electrode located
adjacent the toilet bowl which is charged to a fixed potential and
exhibits an increase in capacitance in response to the presence of
a person in close proximity to the toilet. A charge transfer
circuit detects and measures the change in capacitance. When the
required detection criteria are met a micro-controller in the
charge transfer circuit generates a signal to a switch to close the
circuit between a power source and the exhaust fan motor of the
toilet exhaust system. During the time no signal is being sent to
the switch by the micro-controller, the switch opens the circuit
between the power source and the exhaust fan motor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a toilet with an integrated
exhaust system, partially cut away to show internal details
thereof, with associated detection and motor control circuitry,
motor switch, fan motor and power source shown in block diagram
form;
[0013] FIG. 2 is a block diagram of the detection and motor control
circuitry;
[0014] FIG. 3A and 3B is a process flow diagram of the system of
the present invention, FIG. 3B being a continuation of FIG. 3A;
[0015] FIG. 4 is a graphical depiction of the initial system
settings (null);
[0016] FIG. 5 is a graphical depiction of the system triggered
settings; and
[0017] FIG. 6 is a graphical depiction of the system hold off
settings.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0018] An integrated toilet 10 of the type described in U.S. Pat.
No. 6,019,862 will be used for the purpose of illustrating the
present invention. However, it is to be understood that the present
invention can be used with other types of integrated toilets and
retrofit toilets.
[0019] Integrated toilet 10 has a base 12, a bowl 14, a water
passageway 16 with water outlet openings 17, and an exhaust air
passageway 18 with air intake openings 19.
[0020] A generally U-shaped sensing electrode 20, which preferably
is a conductive, non-magnetic wire antenna, has one leg located
inside one side of exhaust air passageway 18 and the other leg
located inside the other side of exhaust air passageway 18, as
shown. Wire antenna 20 is preferably made of copper. The base 22 of
wire antenna 20 extends out of the rear opening of exhaust air
passageway 18, at the location to which coupling means communicate
exhaust air passageway 18 with the ductwork of an air exhaust
system. Wire antenna 20 does not go all the way around the toilet
bowl as does exhaust air passageway 18, but each leg thereof
terminates at a mid-portion of the toilet bowl opening, as
shown.
[0021] The capacitance of charged wire antenna 20 increases upon a
person coming into close proximity thereto. The physics of such
changes in capacitance is well known. By charging sensing electrode
20 (which can be made of anything conductive) to a fixed potential,
then transferring that charge to a charge detector comprising
another known capacitor, the capacitance of the sensing electrode
20 can be readily ascertained. Any mass moving into proximity to
the sensitized electrode 20 will produce a change (increase) in its
inherent capacitance.
[0022] A detection and motor control circuit 30 includes a charge
transfer sensing integrated circuit 32 (hereinafter referred to as
the "charge sensing IC 32") and a micro-controller integrated
circuit 34 (hereinafter referred to as the "micro-controller
34").
[0023] Charge sensing IC 32 is connected to wire antenna 20 by
signal and power transmitting wire 24.
[0024] Micro-controller 34 is connected to high current motor
switch 40 by wiring 36, and high current motor switch 40 is
connected to exhaust fan motor 50 by wiring 42.
[0025] The detection and motor control circuit 30 and high current
motor switch 40 are both connected to DC power source 60 by wiring
62.
[0026] Reference is now made to the system process flow diagram
shown in FIGS. 3A and 3B which outline the various system process
steps.
[0027] When power is first supplied to the detection and motor
control circuit 30, the System Initialization Process starts. In
the System Initialization Process, micro-controller 34 configures
the charge sensing IC 32 to a predetermined state. The charge
sensing IC 32 generates a digital output that ranges from a value
of 0 to a value of 255. This value corresponds to the relative
value of capacitance seen at the wire electrode 20. The
micro-controller 34 sends a calibrate command to the charge sensing
IC that causes it to null or zero its digital output value. This
action taken by the charge sensing IC 32 sets the current charge
detection level to zero, in effect nulling out the current or
background charge levels. Any change in the charge detected will be
relative to the current background charge level.
[0028] Micro-controller 34 then sends a command to the charge
sensing IC 32 that sets the detection sensitivity to a
predetermined value. The sensitivity setting used ensures that
contact with the toilet by an individual is necessary for any
significant change in the detected charge to occur. This minimizes
any false detection that may occur if an individual is merely in
close proximity to the toilet 10.
[0029] Once the System Initialization Process is completed the
detection and motor control circuit 30 proceeds to the System Armed
State. In the System Armed State micro-controller 34 periodically
interrogates the charge sensing IC 32 to determine the current
charge detection value. If human contact is made with toilet 10 the
charge value will increase. The sensitivity settings of the charge
sensing IC 32 are configured in such a manner that significant
contact with toilet 10 must be made for the charge value to
increase greatly. This would correspond to an individual sitting on
the toilet 10. If the charge returned value is greater than a
predetermined value, then a possible system trigger exists. The
possible system trigger must be further qualified before an actual
system trigger can occur. This is done to filter out any
inadvertent contact with toilet 10. The filter ensures that the
system trigger is valid by requiring the charge value to be greater
than the system trigger threshold for a fixed period of time. If at
any point during this validation process the charge value should
fall below the system trigger threshold the filter timer is reset
and the system goes back into an interrogation mode. FIG. 4
graphically illustrates the relationship between the actual charge
value signal and the system settings.
[0030] When all the conditions are met, and the system has
qualified that a valid trigger does exist, the system will enter a
System Triggered State. In the System Triggered State
micro-controller 34 generates the necessary signal to activate fan
motor switch 40 which allows power to flow to exhaust fan motor 50.
Micro-controller 34 will then send the charge sensing IC 32 a set
of commands to first null the charge value output to compensate for
the particular individual sitting on toilet 10. When that operation
is completed a command will be sent to the charge sensing IC 32 to
insert an offset in the charge value so that the charge signals
datum will be set to a value of 128. In this configuration it will
be possible to detect both an increase and decrease in the
capacitance of wire antenna 20. Micro-controller 34 will now
commence polling the charge sensing IC 32 for a decrease in the
charge value. A decrease in the charge value below a predetermined
threshold will indicate that the individual is no longer in contact
with toilet 10. The system then exits the System Triggered State.
FIG. 5 graphically illustrates the relationship between the actual
charge value signal and the system settings in the System Triggered
State.
[0031] The application requires that exhaust fat motor 50 continue
to operate for a fixed period of time after the individual is no
longer in contact with toilet 10. This requirement is met by the
System Hold Off State. When the System Hold Off State is entered
fan motor 50 is still operating. Micro-controller 34 first sets up
an internal timer for a predetermined period of time. Upon
expiration of the predetermined period of time micro-controller 34
will remove the fan actuation signal. In this mode another trigger
event could occur. During the period that the timer is active
micro-controller 34 again polls charge sensing IC 32 for the
current charge value. If the returned charge value becomes greater
than the current trigger threshold a system re-trigger is detected.
As with the initial trigger event that occurs in the System Armed
State, the System Hold Off State employs a trigger filter
algorithm. Again, this filter algorithm provides an amount of noise
immunity for the detection of false re-trigger events. This filter
operates in the same manner as the trigger valid filter that
resides in the System Armed State. If a valid re-trigger event is
detected the system transitions back to the System Triggered State.
The fan motor 50 ON signal is reasserted and the fan motor 50 ON
timer is disabled. The System Hold Off State is reentered only when
the necessary conditions exist to exit the System Triggered State.
If a re-trigger condition is not detected in the System Hold Off
State, the fan motor 50 ON timer will expire. At this time the
micro-controller 34 will de-assert the fan motor ON signal. The
system then transitions back to the System Initialization State
where the entire process begins again. FIG. 6 graphically
illustrates the relationship between the actual charge value signal
and the system settings in the System Hold Off State.
[0032] Micro-controller 30 may be any such device programmed to
carry out the functions described above. One suitable such
programmable device is that manufactured by Quantum Research
Company under the trademark "Q-Prox".
[0033] High current motor switch 40 may be any switch capable of
carrying out the functions described above.
[0034] Although wire antenna 20 has been described as being
preferably located within the exhaust air duct located in the
toilet bowl of an integrated toilet venting system, it may be
placed at other substantially covered places adjacent the bowl of a
toilet in a location capable of detecting the presence of a person
using the toilet, such as being embedded in the toilet seat.
[0035] It will be obvious to those having skill in the art that
many changes may be made to the details of the above-described
embodiments of this invention without departing from the underlying
principles thereof. The scope of the present invention should,
therefore, be determined only by the following claims.
* * * * *