Control device for flavor-generating article

A control device for electrically heated flavor generators. Sensors detect user lip activity associated with taking a draw and trigger heating of flavor-generating materials.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a control device for an article wherein 
flavor-generating materials are heated to release tobacco flavors. More 
particularly, it relates to a device adapted to initiate heating of the 
flavor-generating material. 
2. Description of Related Art 
Flavor-generating articles generally are known in the art. In such 
articles, flavor beds of tobacco or tobacco-derived material are heated to 
release tobacco flavors without producing all the normal products of 
tobacco combustion. In some such devices, a combustible heat source is 
used to heat air which is then drawn past a bed of flavor-generating 
material to heat the material and thereby release the tobacco flavor. In 
other such devices, the flavor-generating material is heated electrically. 
In the above-described devices, the user initiates heating of the 
flavor-generating material by drawing air into his mouth. In the case of 
the combustible heat source device, the air is drawn through or around the 
heat source and then past a bed of flavor-generating material to heat the 
material. For the electrical heat source device, the user's draw is 
detected by a pressure or air flow sensor, which in turn initiates heating 
of the flavor-generating material. 
In the flavor generators described above, there occurs between the start of 
the draw and the release of flavor from the flavor-generating material a 
substantial lapse of time, as compared to that which occurs in 
conventional cigarettes. Users find this lag time to be a negative 
attribute of such flavor generators. Another problem with current flavor 
generators is that some users do not draw air for a long enough period of 
time to permit full release of the flavor materials before the draw is 
complete. Again, this deficiency in current flavor generators can result 
in user dissatisfaction. 
In electrical flavor generators in particular, various non-draw activities 
can create an air flow or pressure change within the device to falsely or 
prematurely initiate the heating sequence. For example, if the user waves 
the article in his hands or otherwise agitates the device, the heating 
mechanism may be falsely triggered. Also, if the user talks while holding 
the article between his lips, the heating mechanism may be falsely or 
prematurely triggered. 
These problems can be avoided by using an entirely different mechanism to 
control the heating sequence. One proposed mechanism involves the use of a 
push button device which the user must activate for each draw. This 
mechanism is itself unattractive, however, because it requires user action 
substantially different than that practiced by smokers of conventional 
cigarettes. 
Accordingly, it is an object of the present invention to provide a control 
device for a flavor-generating article that initiates heating of 
flavor-generating material such that there is only a small lapse of time 
between the start of the user's draw and the delivery of flavor to the 
user. 
It is also an object of this invention to provide a control device that is 
resistant to false non-draw air flow or pressure changes. 
It is a further object of this invention to provide a control device that 
responds to the user's normal smoking behavior to initiate heating of the 
flavor-generating material. 
SUMMARY OF THE INVENTION 
The present invention has been found to overcome the disadvantages of the 
prior art and provides an improved device to initiate heating of 
flavor-generating material. In accordance with the invention, one or more 
sensors are placed at the tip of the mouthpiece of the flavor generator. 
These sensors detect physical, chemical, or electrical changes associated 
with user lip activity, and produce corresponding electric signals. The 
control device monitors these electric signals, and when the signals reach 
certain threshold levels, the control device initiates heating of the 
flavor-generating material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
It has recently been found that the actions of a user's lips when drawing 
on a cigarette are unlike any other activity which occurs when the user is 
smoking a cigarette. The user applies significantly more pressure on the 
filter or mouthpiece end of the cigarette when drawing smoke than at any 
other time. By monitoring with sensors the motor activity of the user's 
lips when placing pressure to the tip of a flavor generator, it is 
possible to initiate heating of the flavor-generating material before the 
user actually starts to draw air through the flavor generator. This 
reduces the lag time between the start of the draw and the delivery of 
flavor to the user. 
The sensors used at the tip of the flavor generator can take many forms, 
depending upon how the motor activity of the lips is to be monitored. For 
example, a pressure sensor, such as a strip of piezoelectric film, can be 
used to monitor the amount of pressure the user applies to the tip of the 
flavor generator. The piezoelectric sensor can also be used to detect the 
change in temperature that occurs when a flavor generator is placed 
between a user's lips. One film which has been found to be acceptable for 
such an application is Kynar.RTM. piezo film manufactured by the Pennwalt 
Corporation. 
In addition to monitoring the change in pressure at the surface of the tip 
of the mouthpiece, it is also possible to detect the start of a draw by 
measuring the electrochemical activity in the user's lips to detect a 
change in that activity that corresponds to the start of a puff. To 
measure this change in electrochemical activity, one can use standard pH 
electrodes, or electrodes which are sensitive to sodium, calcium, or other 
ion levels. For these sensors, microchip-mounted membrane electrodes can 
be used. 
Finally, it also is possible to measure the changes in electrical signals 
associated with the muscular contraction of the lips which accompanies a 
user's draw. To measure the electrical activity associated with a draw, 
current-sensing or preferably voltage-sensing chip-mounted electrodes can 
be used. 
As used in this disclosure, the term "flavor generator" refers to a device 
wherein flavor-generating material is electrically heated to release 
flavor to a user. Such devices are disclosed in co-pending commonly 
assigned U.S. patent applications Ser. Nos. 07/444,746 and 07/444,818, 
both filed on Dec. 1, 1989, and both hereby incorporated by reference in 
their entirety. 
Flavor-generating material can be any material that, when heated, releases 
a flavor-containing substance. Such materials may include tobacco 
condensates or fractions thereof, or tobacco extracts or fractions 
thereof, deposited on an inert substrate. These materials, when heated, 
generate or release a flavor-containing substance (which may include 
nicotine) that can be drawn in by the user. The flavor-generating material 
can also be unburned tobacco or a composition containing unburned tobacco 
that, when heated to a temperature below its burning temperature, 
generates or releases a flavor-containing substance. Any of these 
flavor-generating materials may also include an aerosol-forming material, 
such as glycerine or water, so that the user has the perception of 
inhaling and exhaling "smoke" as in a conventional cigarette. 
As discussed above, the activity exhibited by a smoker's lips when taking a 
draw is significantly different than other activities which occur during 
smoking. One parameter that can be measured is the pressure exerted 
against the filter. The differences in pressure can be used to generate an 
electric signal to trigger the heating of a flavor-generating material. 
FIG. 1 depicts a flavor-generating article 10 with a piezoelectric sensor 2 
attached to the mouthpiece or filter section 3 of the article. A band of 
piezo film is wrapped around the filter, and electric wires are routed 
through the filter paper. The piezo sensor signals are routed through the 
connectors 4 to the control circuits 5. The circuits are powered by a 
block of batteries 6 at the front-end of the article. The control block 5 
houses, among other things, the heater activation control circuit and the 
piezo sensor signal discriminating control circuit, all described later in 
the specification. The control block may also house visible heater 
selection indicators 7, by which the user can visualize how much 
flavor-generating capacity is remaining in the article. Finally, heater 
block 8 houses graphitic sequential heaters, which are wrapped in 
flavor-generating material, and which, when activated, heat the material 
to release flavors to the user. 
The embodiment depicted in the figure is made with a DTI Kynar.RTM. piezo 
film sensor manufactured by Pennwalt. This piezo film sensor was used to 
graphically illustrate the signals which were generated by typical lip 
pressure against the filter of a cigarette. The output of the sensor was 
applied to the data translation interface of a standard personal computer, 
and Lab Tech.RTM. notebook software created by Laboratory Technology 
Corporation of Wilmington, Mass. was used to process and display the data. 
The data was sampled as analog volts at 5 or 20 Hz versus the internal 
clock. The system exhibited significant dampening as the normally seen 
high frequency noise was not present. 
FIGS. 2 and 3 are graphic representations of the signals generated by the 
above-described piezo film sensor. In FIG. 2, the data was recorded at 
five samples per second. FIG. 2 shows the voltages generated by the sensor 
as the article with the sensor was handled, placed between the lips, drawn 
upon, and removed. This pattern of activity was repeated two additional 
times to create the three spikes seen in FIG. 2 at approximately 7 
seconds, 12 seconds, and 18 seconds. The initial handling of the cigarette 
created the small peak at approximately 4 seconds. Following the 
above-described sequence of activity, the cigarette was again handled with 
the fingers to create the smaller peaks shown at 22 and 24 seconds. FIG. 2 
thus clearly demonstrates that simple handling of the article and sensor 
does not produce the high amplitude signal that is produced during the 
user's draw. 
In this example, the effect measured by the sensor was in fact a 
pyroelectric effect. Piezoelectric sensors are also good pyroelectric 
sensors. Here, the sensor was reacting to the change from room temperature 
(approx. 75.degree. F.) to lip/mouth temperature (approx 98.degree. F.). 
In FIG. 3, the smoking article described above was first moved to the 
mouth, drawn upon, and then removed. This sequence was repeated two 
additional times. The signals generated can be seen in FIG. 3 at 3 through 
9 seconds. The smoking article was afterward simply held between the lips 
(at 9 through 12 seconds), and then drawn upon four times (at 12 through 
17 seconds), without removal of the article from the user's mouth. As 
exhibited in this range of the graph, the signals generated by the drawing 
action are significantly different than those generated by merely holding 
the smoking article between the lips. 
Next, the smoking article was held between the lips while talking (at 18 
through 25 seconds), and finally another series of draws were taken (at 26 
through 30 seconds), with the smoking article removed from the mouth after 
each draw. Again, the signals generated by drawing were significantly 
stronger and sharper than those generated by talking. 
A control system embodied within the overall sensor system may be used to 
differentiate between the above-exhibited draw and non-draw, or true and 
false, signals. The control system can thus reduce or eliminate the chance 
that the heating sequence be falsely or prematurely activated. The signal 
generated by the lip sensor is first passed through the control system. 
The system is circuited such that it will only produce an active output 
signal in response to a true draw signal. Only such an active output 
signal will trigger the heater activation control system. 
FIG. 4 depicts a functional block diagram and corresponding circuit-level 
schematics. The circuit-level diagrams of the figure are presented such 
that each subsystem of the circuit is directly under that portion of the 
functional block diagram with which it corresponds. Each of the 
below-described subsystems are, as individual and isolated systems, known 
in the art. A person skilled in the art could design a circuit to 
accomplish each of the subsystem functions. The circuit-level diagrams and 
the values assigned to the components therein thus represent only 
preferred embodiments of the invention, and are meant to be illustrative, 
but not limiting. 
Referring now to the figure, there is depicted a control system that 
includes several subsystems connected in series. The first subsystem is 
the lip sensor 11, as described above. The lip sensor generates an 
electric signal in response to user lip activity. 
The second subsystem is a signal limiter circuit 12 used to block out 
signals above a certain level to protect the circuit components. Although 
not shown on the graphs in FIGS. 2 and 3, the piezo sensor can generate 
high voltage/high frequency signals that could damage the circuit 
components, if not blocked out. This signal limiter function can be 
accomplished by either of the circuits 12 in FIG. 4A, a signal divider and 
diode, or FIG. 4B, a signal follower. 
The third subsystem is a lowpass filter circuit 13 used to eliminate 
signals above a chosen cutoff frequency. The piezo films in some cases 
generate many spurious signals, and these can be eliminated by allowing 
only lower frequency signals to pass through to the rest of the circuit. 
For purposes of this invention, the signals of interest would not usually 
have frequencies above 100 cycles per second. The lowpass filter function 
can be accomplished with the circuits as depicted in the figure. 
The fourth subsystem is a threshold circuit 14 used to produce a signal 
only in response to an incoming signal of at least a preselected threshold 
value. This subsystem reduces or eliminates the low frequency and low 
amplitude signals that might be associated with non-draw activity, e.g., 
finger handling of the piezo sensor. This threshold function can be 
accomplished with a conventional Schmitt Trigger 14(A). The Schmitt 
Trigger is "triggered," and produces an output signal, only in response to 
an incoming signal of a preselected threshold value. 
This threshold function may also be accomplished with the comparator 
circuit (FIG. 4B), wherein the incoming signal is compared with a 
reference signal, and an output signal is produced only if the incoming 
signal exceeds a preselected threshold value. For example, FIG. 2 shows 
signals produced from a user's draw that exceed +6 volts. If the reference 
signal were set at +6 volts, the lower amplitude signals due to finger 
handling would be eliminated. A pulse generator may be incorporated into 
either the comparator or Schmitt Trigger circuits in order to provide the 
output signal power to drive relays or other circuits as needed to trigger 
the heater activation control system. 
If the signal is tested and determined to be a true draw signal, it is 
passed on to the heater activation control system. One embodiment of such 
a heater activation control system is depicted by the schematic diagram in 
FIG. 5. In that figure, a piezoelectric sensor 301 is placed at the tip of 
the mouthpiece of the flavor generator (not shown). The sensor is 
connected to a timer 302 which controls the heating of the 
flavor-generating material. The sensor 301 has two power inputs (V.sub.+ 
and ground) and one output. The output drives the gate of MOSFET switch 
303. The source of MOSFET switch 303 is connected to counter 304 (at pin 
6). The drain of MOSFET switch 303 is connected through an RC circuit 
(resistor 313 and capacitor 317) to timer 302 (at pin 6). 
A standard 4047-type timer 302 in a monostable configuration is connected 
to V.sub.+ (via pins 4, 8, and 14) and to ground (via pins 5, 7, 12, and 
[9]) for negative triggering (through pin 6). Negative triggering is 
accomplished by first maintaining pin 6 positive, and then briefly pulling 
it to ground. This initiates the flavor-generating sequence. When 
triggered, the complementary timer outputs (via pins 10 and 11) change for 
a period of time dependent upon the resistance value R of variable 
resistor 305 (preferably 2M.OMEGA., connected between pins 2 and 3) and 
the capacitance value C of capacitor 306 preferably 1 .mu.F, connected 
between pins 1 and 3). 
A standard 4024-type CMOS counter 304 is connected to V.sub.+ (via pin 14) 
and to ground (via pins 8 and 7), and receives a positive clock pulse from 
timer 302 (via pin 1). Counter 304 is reset to 0 via a positive pulse 
through pin 2. BCD output is provided at pins 12, 11, 9 and 6. Each time 
the timer clock pulse (received at pin 1) changes from positive to ground, 
counter 304 advances one count. Counter 304 counts positive clock pulses 
and converts the count to BCD. Output pin 6 of the counter is connected to 
pin 6 of the timer 302. 
Heater-active indicators 307 (light emitting diodes (LEDS) or other 
indicator devices) are connected to V.sub.+ through an ADG508-type 
multiplexer 308 (via pins 4, 5, 6, 7, 12, 11, 10 and 9) made by Analog 
devices of Norwood, Mass. LEDs 307 are connected to ground via a 2 
k.OMEGA. current-limiting resistor 309. Multiplexer 308 is connected to 
V.sub.+ (via pins 1, 16 and 15). Multiplexer 308 receives BCD input from 
counter 304 and decodes it such that an individual output is selected 
through which V.sub.+ is supplied to the LEDS. 
Each of heaters 311 is connected to ground through a field-effect 
transistor (FET) 312. A particular FET will turn on under control of a 
standard 4028-type CMOS BCD to decimal decoder (via pins 3, 14, 2, 15, 1, 
6, 7 and 4). Decoder 310 is also connected (via pin 11) to the 
complementary output of a timer 302 (also via pin 11). Pin 11 of decoder 
310 is high when the output of timer 302 (pin 10) is low. All outputs of 
decoder 310 remain low if a BCD code greater than or equal to 1001 is 
applied through its inputs. Therefore, an output of decoder 310 can only 
be on during a positive clock pulse to counter 304. Decoder 310 will 
decode a standard BCD 4-bit code input from counter 304 into 1-of-10 
outputs. Decoder 310 is connected to supply voltage V.sub.+ (at pin 16) 
and to ground (at pin 8). Decoder 310 receives BCD input from counter 304 
(at pins 10, 13 and 12). 
Resistor 313 preferably has a value of 1M.OMEGA., while resistors 314, 315 
and 316 preferably each have values of 100M.OMEGA.. Capacitors 317 and 318 
preferably each have values of 0.1 .mu.F. 
Prior to the user's initial draw, the control circuitry is turned on via 
on/off switch 320, or a similar device. The heater-active indicator LED is 
illuminated for the first heater 311. Correspondingly, heater number 1 is 
selected by decoder 310 and awaits firing. Counter 304 is reset to begin 
counting. Timer 302 complementary output at pin 10 (which is the clock to 
counter 304, pin 1) is low and at pin 11 is high. This keeps the heater 
from firing via pin 11 of decoder 310. When there occurs user draw lip 
activity, the lip sensor 301 causes triggering of timer 302. The RC time 
constant is determined by resistor 313 and capacitor 317 such that a pulse 
of desired duration is output from complementary outputs of timer 302. 
Those outputs, connected to pin 11 of decoder 310, go low, causing the 
first heater to be heated. The output at pin 11 returns to high, 
discontinuing heater activation. Since the count of counter 304 has 
advanced by one, the heater active LED selected by multiplexer 308 has 
correspondingly advanced, and the next heater to be fired in sequence has 
been selected via decoder 310. This cycle can be repeated until the final 
heater has been activated. At such time, pin 6 of the counter will go high 
causing timer 302, to become non-triggerable. In such case, the heater 
firing sequence is halted until the circuit is reset. 
To further reduce the chance that the smoking article might be falsely or 
prematurely activated, it is possible to design the control device such 
that two or more separate signals are required to trigger the heating of 
the flavor-generating material. For example, two separate sensors, one 
which measures lip pressure and a second which measures air flow, could be 
used. In this case both the pressing of the user's lips against the 
mouthpiece and the drawing in of air would be required to trigger heating 
of the flavor-generating material. This type of control strategy would 
prevent a misfire in the case where pressure is accidentally applied to 
the mouthpiece by a source other than the user's lips, or in the case 
where the user is interrupted in the process of taking a draw, at a point 
after having applied pressure with his or her lips, but before drawing air 
through the flavor generator. It would also prevent the firing of the 
device by a change in air flow alone. 
Referring now to FIG. 6, there is depicted a functional block diagram and 
circuit-level schematic of one such control system. The control system 
itself includes three subsystems. The first subsystem 21 includes a sensor 
and signal conditioning/ discriminating circuitry. In that first 
subsystem, a lip sensor is used to detect draw activity and to produce a 
corresponding signal. That signal is passed through 
conditioning/discriminating circuitry, like that shown in FIG. 4, to 
discriminate between true and false draw signals, and to produce a 
corresponding logic signal of 0 V, false, or 5 V, true. The second 
subsystem 22 also includes a sensor and signal conditioning/discriminating 
circuitry, and produces a logic signal 0 V, corresponding to a false 
signal, or 5 V, corresponding to a true signal. The second subsystem 
preferably includes a sensor of a different type than that used in 
subsystem 21, since the use of dissimilar sensors should reduce the 
possibility of false signals derived from a single cause. 
The third subsystem is a logical "AND" circuit 23 having as its inputs the 
logic signals from each of the two subsystems described above. The "AND" 
circuit produces a definite output pulse when and only when there is a 
HIGH pulse at the inputs from each of two sensors. This system only 
activates heating of the parent device when true draw signals are produced 
by both sensors, and thus reduces the likelihood of a false triggering of 
the device. 
The use of three or more sensor subsystems should further reduce the 
likelihood of system misfire. The grouping of more than two sensors could 
be accomplished by constructing additional "AND" gates with the addition 
of new sensors. 
The logical "AND" function can be accomplished with the corresponding 
circuit 23(a) as shown in the figure. In this circuit, an operational 
amplifier in summing mode combines the two signals, and thereafter feeds a 
comparator. The comparator is set with a reference above the value for one 
signal, and thus only produces an active output signal if it is fed with 
the sum of two sensor signals. The logical "AND" function can also be 
accomplished with several other well-known circuit arrangements. A pulse 
generator may be incorporated into this system in order to produce an 
output pulse with enough power to drive relays or other circuits as needed 
to trigger the parent device. 
Other combinations of sensors are possible. The pressure sensor can be 
combined with an electrochemical sensor such that the sensor will only 
fire when the mouthpiece is in contact with the user's lips and pressure 
is applied by the lips. It is even possible to design a device which 
monitors multiple parameters, such as lip pressure, electrochemical 
potential at the lips, changes in electrical potential at the lips caused 
by contraction of the muscles, and air flow through the-flavor generator. 
In this last embodiment, only when all the parameters indicate that the 
user is starting to draw will the heating of the flavor-generating 
material be triggered. 
To reduce the lag time in a device using the dual sensor control system 
described above, the lip sensor may be used to activate all elements 
necessary for the heating of the flavor-generating material short of 
actually heating the material. This strategy reduces the processing time 
once the user starts to draw air into the mouth. In other words, one of 
the sensors could be monitored to "wake up" the system, and thus reduce 
power drain when the system is not being used. Alternatively, the lip 
sensor may begin to heat the flavor-generating material at a low energy 
level so that only a portion of the flavor is released. Then, when the 
user draws air through the flavor generator, additional power is supplied 
to the heater causing the release of the remaining flavor materials. In 
this latter embodiment, the user will receive a low level of flavor when 
he first starts to draw air, and that flavor will grow stronger as the 
draw continues. This system more closely approximates the sensation a user 
experiences when he smokes a conventional cigarette. 
It may also be possible to design a control device which can be programmed 
by the user to respond to his particular draw behavior. 
Thus, the above-described control device for electrically heated 
flavor-generating articles reduces or eliminates the lag time between the 
start of a draw and the delivery of flavor to the user, and also reduces 
the possibility of a misfiring of the flavor-generating sequence. One 
skilled in the art will appreciate that the present invention can be 
practiced by other than the described embodiments. The described 
embodiments are thus presented for purposes of illustration, and not of 
limitation.