United States Patent [19]
`Brooks et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,947,874
`Aug. 14, 1990
`
`[75]
`
`[54] SMOKING ARTICLES UTILIZING
`ELECTRICAL ENERGY
`Inventors: Johnny L Brooks; Donald L.
`Roberts, both of Winston-Salem;
`Jerry S. Simmons, Rural Hall, all of
`N.C.
`[73] Assignee: R. J. Reynolds Tobllcco Company,
`Winston-Salem, N.C.
`[21] Appl. No.: 242,086
`
`[51]
`
`[56]
`
`Sep. 8, 1988
`[22] Filed:
`Int. Cl.s .......................... A24D 1/00; A24F 1/00;
`A24F 47/00; A61M 16/00
`[52] U.S. CI. .................................... 131/329; 131/273;
`131/194; 128/202.21; 128/203.26; 128/203.27;
`128/204.21
`[58] Field of Search ....................... 131/329, 194, 273;
`128/202.21, 202.27, 203.12, 203.13, 203.15,
`204.21, 203.17, 203.26, 203.27, 204.13, 204.23
`References Cited
`U.S. PATENT DOCUMENTS
`1,771,366 7/1930 Wyss et al ..
`1,968,509 7/1934 Tiffany .
`2,057,353 10/1936 Whittemore, Jr ..
`2,104,266 1/1938 McCormick .
`2,974,669 3/1961 Ellis .
`3,200,819 8/1965 Gilbert .
`3,889,690 6/1975 Guarnieri .
`3,918,464 11/1975 Kolodziej .
`3,943,941 3/1976 Boyd et al ........................... 131/359
`4,133,318 1/1979 Gross et al ..
`4,141,369 2/1979 Burruss .
`4,164,230 8/1979 Pearlman .
`4,193,411 3/1980 Faris et .al ..
`4,246,913 1/1981 Ogden et al ..
`4,303,083 12/1981 Burruss, Jr ..
`4,523,589 6/1985 Krauser .
`4,564,748 1/1986 Gupton .
`4,580,583 4/1986 Green, Jr ..
`
`4,708,151 11/1987 Shelar .
`4,714,082 12/1987 Banerjee et al ..
`4,735,217 4/1988 Gerth et al ..
`4,756,318 7/1988 Clearman et al •.
`4,771,796 9/1988 Myer .
`
`FOREIGN PATENT DOCUMENTS
`174645 3/1986 European Pat. Off ..
`186280 7/1986 European Pat. Off ..
`212234 3/1987 European Pat. Off ..
`2653133 5/1978 Fed. Rep. of Germany .
`2704218 8/1978 Fed. Rep. of Germany .
`3300992 7/1984 Fed. Rep. of Germany .
`2128256 10/1972 France .
`48-8231 3/1973 Japan .
`W086/02528 5/1986 PCT Int'! Appl. .
`197946 4/1924 United Kingdom .
`
`OTHER PUBLICATIONS
`Tobacco and Tobacco Smoke, Wynder et al., pp. 482 and
`522 (1967).
`
`Primary Examiner-V. Millin
`ABSTRACT
`[57]
`Smoking articles employ an electrical resistance heating
`element and an electrical power source to provide a
`tobacco-flavored smoke or aerosol and other sensations
`of smoking. The smoking articles advantageously com(cid:173)
`prise a disposable portion and a reusable controller. The
`disposable portion, which may be a cigarette, normally
`includes (i) an air permeable resistance heating element
`having a surface area greater than 1 m2/g, which usu(cid:173)
`ally carries an aerosol forming material, and (ii) a
`charge or roll of tobacco. The reusable controller nor(cid:173)
`mally includes a puff-actuated current actuation means,
`a time-based current regulating means to control the
`temperature of the heating element, and a battery
`power supply.
`
`202 Claims, 8 Drawing Sheets
`
`58
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`NU MARK Ex.1006 p.1
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`U.S. Patent Aug.14, 1990
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`U.S. Patent Aug. 14, 1990
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`NU MARK Ex.1006 p.4
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`U.S. Patent Aug. 14, 1990
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`Sheet 4of8
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`NU MARK Ex.1006 p.5
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`Aug. 14, l99tJ
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`NU MARK Ex.1006 p.6
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`

`
`1
`
`4,947,874
`
`SMOKING ARTICLES UTILIZING ELECTRICAL
`ENERGY
`
`2
`coil. Heat produced by the resistance coil was transmit(cid:173)
`ted to the tobacco in the bowl or holder, resulting in the
`volatilization of various ingredients from the tobacco.
`A thermostatic switch was employed to maintain a
`BACKGROUND OF THE INVENTION
`5 predetermined temperature range to which the tobacco
`was heated.
`The present invention relates to cigarettes and other
`U.S. Pat. No. 3,200,819 to Gilbert proposed a smoke-
`smoking articles such as cigars, pipes, and the like,
`less, non-tobacco cigarette having a flavor cartridge,
`which employ an electrical resistance heating element
`and an electrical power source to produce a tobacco-
`such as a porous substrate impregnated with mentho-
`flavored smoke or aerosol.
`10 lated water. The article included a battery for powering
`a tube or bulb which was illuminated before assembly.
`Preferred smoking articles of the invention are capa-
`The bulb was placed in a tubular liner, which was in
`ble of providing the user with the sensations of smoking
`turn located within a tube of plastic having the size,
`(eg., smoking taste, feel, satisfaction, pleasure, and the
`color and form of a cigarette. In use, the illuminated
`like), by heating but not burning tobacco, without pro-
`ducing sidestream smoke or odor, and without produc- 15 bulb reportedly heated the flavored air drawn through
`ing carbon monoxide. As used herein, the term "smok-
`passages formed between the bulb and the tubular liner.
`ing article" includes cigarettes, cigars, pipes, and the
`As such, warm, moist, flavored air was delivered to the
`like, which use tobacco in various forms.
`user.
`Many smoking articles have been proposed through
`French Patent Publication No. 2, 128,256 to Ribot et
`the years as improvements upon, or alternatives to, 20 al proposed an article for delivering denicotinized
`smoking products which burn tobacco.
`smoke. The proposed article included a sealed ampule
`which contained pressurized denicotinized smoke. An
`Many tobacco substitute smoking materials have been
`proposed, and a substantial listing of such materials can
`electric resistor was immersed in the smoke. In use, the
`be found in U.S. Pat. No. 4,079,742 to Rainer et al.
`terminals of the resistor were pushed into contact with
`Tobacco substitute smoking materials having the trade- 25 a microbattery causing the resistor to generate heat and
`heat the smoke within the ampule. Draw by the user
`names Cytrel and NSM were introduced in Europe
`during the 1970's as partial tobacco replacements, but
`reportedly caused warm smoke to exit a valve near the
`did not realize any long-term commercial success.
`mouthend of the article.
`Numerous references have proposed smoking articles
`which generate flavored vapor and/or visible aerosol. 30
`Japanese Patent Publication 8231/73 to Takeda pro-
`posed a cigar-shaped inhaler which included a battery
`Most of such articles have employed a combustible fuel
`source to provide an aerosol and/or to heat an aerosol.
`powered Nichrome wire to heat air that, in tum, evapo-
`·ted · u s p t
`rated an essence from an essence container. The Ni-
`th b k 0 d art
`see "or exam 1
`,.,
`pe, e acgrun
`c1 m .. a.
`chrome wire was energized by either a manually-
`No. 4,714,082 to Banerjee et al.
`However, despite decades of interest and effort, no 35 actuated or a draw actuated "on-ofr' switch.
`West German Patent Application No. 2,653,133 to
`one had successfully developed a smoking article which
`provided the sensations associated with cigarette or
`Kovacs proposed a smoking simulator having an inter-
`nal battery which could accelerate or control the vapor-
`pipe smoking, without delivering considerable quanti-
`ties of incomplete combustion and pyrolysis products.
`ization or emission of aromatic substances for delivery
`Recently, however, in European Patent Publication 40 to the user. In supplemental West German Patent Ap-
`Nos. 174,645 and 212,234, and U.S. Pat. Nos. 4,708,151,
`plication No. 2,704,218, Kovacs described the use of a
`4,714,082, and 4,756,318, assigned to R. J. Reynolds
`vacuum or draw-actuated switch to switch "on" the
`Tobacco Co., there are described smoking articles
`battery operated heating coil.
`which are capable of providing the sensations associ-
`A draw actuated, pressure transducer switch was
`ated with cigarette and pipe smoking, by heating but not 45 described in U.S. Pat. No. 4,246,913 to Ogden et al, as
`part of a smoke aversion therapy article which deliv-
`burning tobacco, and without delivering considerable
`quantities of incomplete combustion-cproducts. Such
`ered a small electrical shock to a smoker whenever the
`articles rely on the combustion of a fuel element for heat
`smoker drew on a cigarette.
`generation, resulting in the production of some combus-
`U.S. Pat. No. 4,141,369 to Burruss proposed an article
`50 similar to the previously discussed McCormick articles.
`tion products.
`Over the years, there have been proposed numerous
`Burruss proposed a container which was electrically
`smoking products, flavor generators and medicinal in-
`heated to a temperature sufficient to volatilize desired
`balers which utilize electrical energy to vaporize or
`components from smoking material inserted therein.
`heat a volatile material, or attempt to provide the sensa-
`Heated air passing through the container during draw
`tions of cigarette or pipe smoking without burning to- 55 reportedly carried volatilized materials to the mouth of
`bacco.
`the user.
`U.S. Pat. No. 2,057,353 to Whittemore, Jr. proposed
`U.S. Pat. No. 4,303,083 to Burruss proposed a pipe
`a vaporizing unit. In particular, a wick reportedly car-
`having an electrical resistance heating element, a manu-
`ried liquid medicament by capillary action to a point
`ally operated "on-ofr' power switch, and an opening
`where the liquid was vaporized by an electrical resis- 60 above the resistance element for the addition of volatile
`tance heating element.
`compound. During use, the volatile compound was
`U.S. Pat. No. 2,104,266 to McCormick proposed an
`applied, using a squeeze tube or eye dropper, to a heated
`article having a pipe bowl or cigarette holder which
`surface within the pipe, apparently on a puff-by-puff
`included a resistance coil (i) wound on an insulating and
`basis. The volatile compounds reportedly were vapor-
`heat resisting material, and (ii) contained in an insulated 65 ized, mixed with air drawn into the pipe, and inhaled by
`chamber. Prior to use of the article, the pipe bowl was
`the user.
`filled with tobacco or the holder was fit with a ciga-
`PCT Publication No. WO 86/02528 to Nilsson et al
`rette. Current then was passed through the resistance
`proposed an article similar to that described by McCor-
`
`NU MARK Ex.1006 p.10
`
`

`
`4,947,874
`
`4
`3
`pyrolysis products including carbon monoxide or any
`mick. Nilsson et al proposed an article for releasing
`sidestream smoke or odor. Preferred articles can pro-
`volatiles from a tobacco material which had been
`duce aerosol almost immediately upon commencement
`treated with an aqueous solution of sodium carbonate.
`of a puff, as well as provide the controlled production
`The article resembled a cigarette holder and reportedly
`included a battery operated heating coil to heat an un- 5 of aerosol throughout the puff and over the 6 to 10 puff
`life of a typical cigarette.
`tipped cigarette inserted therein. A switch was acti-
`In one aspect of the invention, the smoking article
`vated to supply current to the heating coil. A tempera-
`ture sensor reportedly disconnected and reconnected
`includes a cigarette or a disposable portion (eg., a car-
`the battery in order to maintain the temperature gener-
`tridge) which utilizes an air permeable high surface area
`ated by the device in a narrow temperature range. Air 10 electrical resistance heating element that normally
`drawn through the device reportedly was subjected to
`carries aerosol forming and/or tobacco flavor sub-
`elevated temperatures below the combustion tempera-
`stances prior to use. This resistance heating element
`ture of tobacco and reportedly liberated tobacco flavors
`typically is a porous material having a surface area
`greater than l m2/g, as determined using the Brunaver,
`from the treated tobacco contained therein.
`U.S Patent No. 4,735,217 to Gerth et al proposed a 15 Emmett and Teller (BET) method described in J. Am.
`"cigarette-shaped" medicament dosing article having a
`Chem. Soc., Vol. 60, p. 309 (1968); and Adsorption Sur-
`pellet of vaporizable medicament and a Nichrome resis-
`face Area and Porosity, Gregg et al, Academic Press,
`tance heating element connected in series with a battery
`N.Y. (1967). Preferably, the heating element is a fibrous
`power source and a draw actuated switch. In their only
`carbon material, most preferably having a surface area
`working example, the Nichrome heating element alleg- 20 greater than about 1,000 m2g. (In contrast, the surface
`area of the Nichrome metal resistance element of Gerth
`edly achieved a temperature in the range of 190° F. to
`220° F. (90° C. to 105° C.) within a two second puff,
`et al is believed to be about 0.01 m2g.) Preferably, such
`which apparently was sufficient to volatilize menthol
`porous heating elements are impregnated with liquid
`from a menthol pellet. At Column 8, lines 43-63, Gerth
`aerosol forming substances, such as glycerin, and with
`et al. went on to speculate that their article could be 25 tobacco extracts. Such heating elements are particularly
`used to vaporize nicotine from a nicotine-containing
`advantageous in that they are capable of holding and
`efficiently releasing relatively large quantities of liquid
`pellet and that they believed it feasible to coat the heat-
`ing element with a nicotine-containing compound in
`aerosol forming substances and tobacco flavor materi-
`lieu of using a vaporizable pellet.
`als. For example, such heating elements can carry
`However, it is believed that it would not be possible 30 enough aerosol forming substances to provide aerosol
`for 6 to 10 puffs, or more.
`to coat a Nichrome heating element, of the type de-
`The cigarette or disposable portion includes tobacco,
`scribed by Gerth et al, with enough vaporizable liquid
`material to deliver sufficient volatile material to the
`such as a roll or charge of cut filler. Other forms of
`user, over the 6 to 10 puff life of a typical cigarette. It
`tobacco also can be used.
`also is believed that the article of Gerth et al would not 35 Another aspect of the invention relates to a reusable
`controller which can be used with the cigarettes or
`be able to provide enough electrical energy to (i) vapor-
`ize volatile material until near the end of a typical two
`disposable portions of the invention, as well as with
`second puff, or (ii) provide a high enough temperature
`other resistance heating aerosol producing articles. This
`(e.g., 150° C. to 350° C.) to vaporize many volatile
`reusable controller normally includes a current actua-
`materials within a two second puff, including many 40 tion means, a separate current regulating means to con-
`desirable aerosol forming substances and most volatile
`trol the temperature of the heating element, and a bat-
`tobacco flavor components. In addition, even with only
`tery power supply. Alternatively, the electrical power
`a single AA battery, the article described by Gerth et al.
`supply can be provided separately from the current
`is more than 3 times the diameter and many times
`actuation and current regulating means; e.g., as a sepa-
`heavier than a typical cigarette and is provided with a 45 rate battery pack or as normal household current
`relatively imprecise draw actuated control switch and
`stepped down by an appropriate transformer. The reus-
`with no means of regulating the current or heat during
`able controller can be in the form of a pipe, a reusable
`the puff.
`cigarette holder, or a hand-held unit or other portable
`Despite many years of interest and effort, none of the
`form into which the disposable portion can be inserted.
`foregoing articles employing electrical energy has ever SO The use of such a reusable article with the cigarette and
`realized any significant commercial success, and it is
`disposable portions of the invention is particularly ad-
`believed that none has ever been widely marketed.
`vantageous in that it permits the use of (i) relatively
`Moreover, it is believed that none of the foregoing
`large power sources, capable of generating 10 to 40
`electrical energy articles is capable of providing the
`watts of power or more, and (ii) accurate and sophisti-
`user with the sensations of cigarette or pipe smoking.
`55 cated current actuation and current regulating means
`Thus, it would be desirable to provide a smoking
`that normally would be too costly to incorporate into a
`article which can provide the sensations of cigarette or
`single use, disposable article.
`Preferably, the current actuation means is puff actu-
`pipe smoking, which does not burn tobacco or other
`material, and which does not produce combustion prod-
`ated, so that current flows through the resistance heat-
`ucts.
`60 ing element to produce aerosol only during draw by the
`user.
`The current regulating means normally functions
`only during periods of current actuation, and preferably
`is time based. That is, the current regulating means
`preferably is based on controlling the time period dur(cid:173)
`ing which current passes through the resistance element
`during draw. This, in turn, controls the temperature
`experienced by the resistance element and by the aero-
`
`SUMMARY OF THE INVENTION
`The present invention relates to cigarettes and other
`smoking articles which employ an electrical resistance
`heating element and an electrical power source to pro- 65
`vide a tobacco-flavored smoke or aerosol and other
`sensations of smoking, without burning tobacco or
`other substances, without producing any combustion or
`
`NU MARK Ex.1006 p.11
`
`

`
`4,947,874
`
`5
`sol forming substances. The current regulating means
`normally includes an electrical control circuit which
`maximizes initial heating of the heating element, until a
`desired temperature range for volatilization of the aero(cid:173)
`sol former and the tobacco flavor substances is reached, 5
`usually between about 150° C. and about 350° C. There(cid:173)
`after, the control circuit, by regulating, restricting or
`interrupting current flow through the resistance ele(cid:173)
`ment, normally maintains the heating element within
`the desired temperature range during the balance of the 10
`puff and/or ensures that the heating element does not
`overheat during puffmg.
`Preferably, the time-based current regulating means
`includes a means for permitting uninterrupted current
`flow through the heating element for an initial period 15
`after current actuation, thus permitting rapid heating of
`the resistance element. The current regulating means
`preferably includes a timer means for subsequently reg(cid:173)
`ulating or interrupting current flow through the heating
`element, such as by repeated off-on switching, to con- 20
`trol the average current flow through the heating ele(cid:173)
`ment during the balance of the puff. This, in turn, con(cid:173)
`trols the temperature range experienced by the heating
`element. More preferably, the current regulating means
`also includes a means to prevent the heating element 25
`from overheating during rapid puffmg.
`Depending upon factors such as the wattage gener(cid:173)
`ated by the power source and the resistivity of the heat(cid:173)
`ing element, preferred current regulating means of the
`invention are capable of producing almost immediate 30
`aerosol generation upon puffing, preferably within
`about 0.5 second, more preferably within about 0.1
`second. Such preferred regulating means also ensure
`that sufficient aerosol forming and tobacco flavor sub(cid:173)
`stances remain for later puffs, and that such substances 35
`are not degraded by exposure to excessive tempera(cid:173)
`tures.
`To use the smoking articles of the invention, the user
`simply inserts the cigarette or disposable portion into
`the controller, to electrically connect the heating ele- 40
`ment to a circuit including the current actuation and
`current regulating means and to the battery. When the
`user draws on the mouthend of the article, the preferred
`current actuation and current regulating means permit
`unrestricted or uninterrupted flow current through the 45
`resistance heating element to generate heat rapidly.
`This heating volatilizes the aerosol forming and/or
`tobacco flavor substances, which in turn form an aero-
`sol and pass through the article and into the mouth of
`the user. At the same time, the current regulating means 50
`(i) regulates current flow through the heating element
`to control heating of the resistance element and the
`temperature experienced thereby, and (ii) prevents
`overheating and degradation of the aerosol former.
`When the user stops drawing on the article, the current 55
`actuation means prevents further current flow through
`the heating element and disables the current regulating
`means. This process continues, puff after puff, until the
`user decides to stop drawing on the article. At that
`point, the cigarette or disposable portion can be re- 60
`moved and discarded, and a new one inserted in its
`place.
`Another important aspect of the invention relates to
`the various configurations of the cigarette or disposable
`portions described herein. For example, in certain pre- 65
`ferred embodiments, the disposable portion advanta(cid:173)
`geously is provided with an electrical connection means
`at one end thereof. This electrical connection means
`
`6
`includes means for connecting the resistance element to
`the battery or other external power source, and prefera(cid:173)
`bly includes an air passageway used in conjunction with
`the preferred puff actuated current actuation means. In
`other preferred embodiments, the disposable portion is
`adapted for connection to the external power source via
`connectors located on the reusable controller. In certain
`preferred embodiments, the resistance heating element
`is located centrally in the disposable portion and/or
`does not occupy a significant portion of the cross-sec(cid:173)
`tional area of the disposable portion. In other preferred
`embodiments, the resistance heating element is located
`adjacent an end of the disposable portion, and/or at
`least substantially fills the cross-sectional area of the
`disposable portion or the air passageway therethrough.
`In another aspect of the invention, the current actua(cid:173)
`tion means, the current regulating means, and/or the
`electrical power source may be incorporated into the
`portion of the smoking article containing the electrical
`resistance heating element, so that the reusable control(cid:173)
`ler may be reduced in size or even eliminated.
`Yet another aspect of the invention relates to a cur(cid:173)
`rent control circuit for resistance heating aerosol pro(cid:173)
`ducing articles which includes the current regulating
`means described herein.
`Preferred smoking articles of the invention are capa(cid:173)
`ble of delivering an average of at least 0.5 mg, more
`preferably at least 0.8 mg, of aerosol per puff, measured
`as wet total particulate matter (WTPM), under standard
`FTC smoking conditions of 2 second, 35 ml puffs, taken
`once every 60 seconds. Preferred smoking articles of
`the invention can deliver such aerosol, preferably in
`visible form, for a plurality of puffs, preferably at least
`about 6 puffs, more preferably at least about 10 puffs,
`under such conditions.
`Smoking articles of the invention also are capable of
`providing an aerosol which is chemically simple. A
`chemically simple aerosol consists essentially of air, the
`aerosol former, tobacco volatiles, and desired flavor(cid:173)
`ants. This aerosol preferably has no significant muta(cid:173)
`genic activity according to the Ames test; Ames et al,
`Mut. Res., 31:347-364 (1975); Nagao et al, Mut. Res.,
`42:335 (1977).
`As used herein, and only for the purposes of this
`application, "aerosol" is defined to include vapors,
`gases, particles, and the like, both visible and invisible,
`and especially those components perceived by the user
`to be "smoke-like," generated by action of heat from the
`resistance heating element upon aerosol forming sub(cid:173)
`stances and/or tobacco flavor substances located on the
`resistance element or elsewhere in the article.
`The articles of the present invention are described in
`greater detail in the accompanying drawings and in the
`detailed description of the invention which follows.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a longitudinal, partial sectional view of a
`smoking article of this invention;
`FIG. lA is a sectional view of a portion of the em(cid:173)
`bodiment shown in FIG. 1 taken along lines 1-1;
`FIG. 2 is a longitudinal, partial sectional view of a
`smoking article of this invention;
`FIG. 3 is a perspective of a smoking article of this
`invention including an exposed inner view of the reus(cid:173)
`able portion thereof;
`FIGS. 4, 5, and 6 are longitudinal, partial sectional
`views of preferred smoking articles of this invention
`
`NU MARK Ex.1006 p.12
`
`

`
`4,947,874
`
`7
`showing the disposable portions and cut-away views of
`the controllers;
`FIGS. 7 and 8 are longitudinal sectional views of
`additional smoking articles of the invention;
`FIGS. 9 and 10 are representative schematic dia- 5
`grams of time-based control circuits and related wiring
`for preferred controllers of the invention; and
`FIG. 11 depicts the temperature, average current and
`average voltage profiles experienced by a resistance
`heating element during heating controlled by the pre- IO
`ferred current regulating means of the invention.
`
`25
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`Referring to FIG. 1, smoking article 10 includes a 15
`cigarette 12 and a reusable, hand-held controller 14.
`The cigarette U includes electrical connection plug 16,
`resistance heating element 18 carrying an aerosol form(cid:173)
`ing substance, a roll of tobacco 20, mouth end filter 22,
`and a resilient overwrap 24. The preferred controller 14 20
`includes a case 26, a puff actuated current actuation
`mechanism 28 having the form of a pressure sensitive
`switch, a time-based current control circuit 30, and a
`chamber 32 into which battery power supply 34 (shown
`as batteries 34A and 34B) is inserted.
`The resistance heating element 18 employed in ciga(cid:173)
`rette 12 preferably is a fibrous material having a high
`surface area and an adsorbant, porous, wettable charac(cid:173)
`ter, in order to carry a suitable amount of aerosol form(cid:173)
`ing substance for effective aerosol formation. Suitable 30
`heating elements preferably have surface areas above
`about 50 m2g, more preferably above about 250 m2g,
`and most preferably above about 1,000 m2g.
`Preferred heating elements normally have low mass,
`low density, and moderate resistivity, and are thermally 35
`stable at the temperatures experienced during use. Such
`heating elements heat and cool rapidly, and thus pro(cid:173)
`vide for the efficient use of energy. Rapid heating of the
`element also provides almost immediate volatilization
`of the aerosol forming substance. Rapid cooling pre- 40
`vents substantial volatilization (and hence waste) of the
`aerosol forming substance during periods when aerosol
`formation is not desired. Such heating elements also
`permit relatively precise control of the temperature
`range experienced by the aerosol forming substance, 45
`especially when the preferred time based current con(cid:173)
`trol means of the invention is employed.
`Preferred resistance heating elements include carbon
`filament yams available from American Kynol, Inc.,
`New York, N.Y., as Catalog Nos. CFY-0204-1, CFY- 50
`0204-2, and CFY-02()4:.3. Such yams typically have
`surface areas of about 1,500 m2g and resistivities of
`about 10 to about 30 milliohm-cm. See, Kirk-Othmer:
`Encycl. Chem. Tech., Vol. 16, 3rd Ed., pp. 135-136
`(1981). Representative lengths of such yams range from 55
`about 15 mm to about 50 mm. Other preferred heating
`elements include carbon felts and activated carbon felts
`available from American Kynol, Inc., as Catalog Nos.
`CN-157(HC), CN-210(HC), ACN-211-10, ACN-210-10,
`and ACN-157-10. Such felts typically have surface 60
`areas of about 1,500 m2g and resistivities of about 5 to
`about 30 milliohm-cm. Such felts can be used in the
`form of circular discs having diameters of about 4 to 8
`mm, as described in greater detail hereinafter with ref(cid:173)
`erence to FIGS. 4-6. Other suitable heating elements 65
`include porous metal wires or films; carbon yams,
`cloths, fibers, discs or strips; graphite cylinders, fabrics
`or paints; microporous high temperature polymers hav-
`
`8
`ing moderate resistivities; porous substrates in intimate
`contact with resistance heating components; and the
`like.
`Preferably, the heating element 18 is impregnated
`with or otherwise carries the aerosol forming substance
`in order that the aerosol forming substance is in a heat
`exchange relationship with the electrical heating ele(cid:173)
`ment. The aerosol forming substance can be, for exam(cid:173)
`ple, a polyhydric alcohol, such as glycerin, propylene
`glycol, or a mixture thereof; water; a tobacco material
`such as a tobacco aroma oil, a tobacco essence, a spray
`dried tobacco extract, a freeze dried tobacco extract,
`tobacco dust, or the like, in order to provide tobacco
`flavor; or a combination thereof. Other suitable aerosol
`forming substances are well known in the art. See, for
`example, U.S. Pat. Nos. 4,714,092 and 4,756,318. While
`the loading of the aerosol forming substance can vary
`from substance to substance and from heating element
`to heating element, the amount of liquid aerosol form(cid:173)
`ing substance used typically will be greater than about
`15 mg and preferably ranges from about 25 mg to about
`50mg.
`A heat resistant, electrically insulative strip, tube or
`spacer 36, preferably is provided in order to maintain
`the heating element in place and to prevent the heating
`element from contacting itself. The insulative spacer 36
`can be a heat resistant plastic material (such as a poly(cid:173)
`imide), a cellulosic sheet treated with fire retardant, an
`aluminum foil having a surface coating of aluminum
`oxide, an insulative ceramic material, or the like.
`The electrical connection plug 16 preferably is manu(cid:173)
`factured from a resilient, electrically insulative material
`such as a thermoplastic material. The plug 16 includes
`two electrical connector pins or prongs 38, 39 con(cid:173)
`nected to the ends of heating element 18 via connectors
`40, 41. The pins 38, 39 engage with electrical terminals
`42, 43 located in electrical connection receptacle 44 of
`the controller 14. Plug 16 also includes a passageway 46
`through which tube 48 from pressure sensing switch 28
`extends. As shown in FIG. lA, pins 38, 39 and passage(cid:173)
`way 46 are offset with respect to the longitudinal axis of
`plug 16.
`A portion of the length of the electrical connection
`plug 16 preferably is circumscribed by a collar 49 hav(cid:173)
`ing the form of a thermoplastic tube, which preferably
`is friction fit around a portion of the length of the plug.
`The collar 49 in tum is secured to the remaining portion
`of the cigarette via overwrap 24 using tipping paper 52
`or other appropriate means such as adhesive, a friction
`fit, or the like. Preferably, the collar 49 includes one or
`more peripheral air inlet openings 54 which provide a
`flow of ambient air through the cigarette during draw.
`Alternatively, the air inlet can be positioned through
`the extreme inlet end of the cigarette or elsewhere
`through the periphery of the cigarette, such that drawn
`ambient air passing through the cigarette to the mouth
`of the user passes the resistance element.
`The cigare