United States Patent (19
`Deevi et al.
`
`54 ELECTRICALLY POWERED CERAMIC
`COMPOSITE HEATER
`
`75 Inventors: Seetharama C. Deevi, Midlothian; A.
`Clifton Lilly, Jr., Chesterfield, both of
`Va.
`
`73 Assignee: Philip Morris Incorporated, New
`York, N.Y.
`
`(21) Appl. No.: 291,690
`22 Filed:
`Aug. 16, 1994
`
`Related U.S. Application Data
`63 Continuation-in-part of Ser. No. 224,848, Apr. 8, 1994,
`which is a continuation-in-part of Ser. No. 118,665, Sep. 10,
`1993, Pat. No. 5,388,594, which is a continuation-in-part of
`Ser. No. 943,504, Sep. 11, 1992.
`(51) Int. Cl. .............................. H05B 3/10; A24F 1/22
`(52)
`219,1553; 219/543; 131/194
`58 Field of Search ..................................... 219/553, 541,
`219/543, 544, 390; 338/283, 284, 285,
`294; 373/111, 117; 252/516, 518; 264/60;
`131/194, 195
`
`56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`8/1946 Wejnarth.
`2,406,275
`2.971,039
`2/1961 Western .................................. 219,553
`3,875,476
`4/1975 Crandall et al. .
`7/1975 Richerson et al.
`3,895,219
`4,098,725
`7/1978 Yamamoto et al..
`4,110,260 8/1978 Yamamoto et al. .
`4,327,186 4/1982 Murata et al..
`4,407,971 10/1983 Komatsu et al. ......................... 501/97
`4,416,840 11/1983 Lee et al. .................................. 264/60
`4,449,039 3/1984 Fukazawa et al. ...................... 219,553
`(List continued on next page.)
`FOREIGN PATENT DOCUMENTS
`1298808 12/1972 United Kingdom.
`
`
`
`IIII
`USOO5498855A
`11, Patent Number:
`(45) Date of Patent:
`
`5,498,855
`Mar 12, 1996
`
`OTHER PUBLICATIONS
`"Joining of Ceramics' by R. E. Loehman et al., published in
`Ceramic Bulletin, 67(2):375-380 (1988).
`"Oxidation Behavior of Silver- and Copper-Based Brazing
`Filler Metals for Silicon Nitride/Metal Joints' by R. R.
`Kapoor et al., published in J. Am. Ceram. Soc.,
`72(3):448-454 (1989).
`"Brazing Ceramic Oxides to Metals at Low Temperatures”
`by J. P. Hammond et al., published in Welding Research
`Supplement, 227-232–s, (1988).
`"Brazing of Titanium-Vapor-Coated Silicon Nitride” by M.
`L. Santella published in Advanced Ceramic Materials,
`3(5):457-465 (1988).
`a
`with
`Brazed
`Alumina
`"Microstructure
`of
`Silver-Copper-Titanium Alloy' by M. L. Santella et al.,
`published in J. Am. Ceram. Soc., 73(6):1785-1787 (1990).
`“High Temperature Structural Silicides' by A. K. Vasudevan
`et al., Elsevier Science Publishers B.W. (1992).
`John A. Dean, Lange's Handbook of Chemistry, 12th Edi
`tion, 1978 pp. 4-16, 4-123.
`Primary Examiner Teresa J. Walberg
`Assistant Examiner Sam Paik
`Attorney, Agent, or Firm-Burns, Doane, Swecker & Mathis
`57
`ABSTRACT
`An electrically powered ceramic composite heater useful for
`devices such as a cigarette lighter. The electrical resistance
`heater includes a discrete heating segment configuration
`wherein each individual segment of the heater can be
`activated using an electric control module, and is capable of
`heating to a temperature in the range of 600° C. to 900° C.
`using portable energy devices. The ceramic heater can be
`made by extrusion of a ceramic precursor material followed
`by secondary processing steps to obtain discrete heating
`segments. The heater design is such that a hub on one end
`of the heater provides structural integrity, and functions as a
`common for the electrical terminals. The ceramic heater can
`include one or more insulating or semiconductive metal
`compounds and one or more electrically conductive metal
`compounds, the compounds being present in amounts which
`provide a resistance which does not change by more than
`20% throughout a heating cycle between ambient tempera
`tures and 900 C.
`
`49 Claims, 8 Drawing Sheets
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 001
`
`

`

`5,498,855
`Page 2
`
`U.S. PATENT DOCUMENTS
`4,475,029 10/1984 Yoshida et al. ......................... 219/553
`4,503,319 3/1985 Moritoki et al......
`... 219/553
`4,528,121 7/1985 Matsushita et al. .
`... 252/516
`4,549,905 10/1985 Yamaguchi et al. .................... 219/553
`4,555,358 11/1985 Matsushita et al. .
`4,634,837
`1/1987 Ito et al. ................................. 219/553
`5,045,237 9/1991 Washburn.
`
`
`
`5,060,671 10/1991 Counts et al. .
`04
`W
`5,085,804 2/1992 Washburn
`5,093,894 3/1992 Deevi et al..
`264/60
`5,139,594
`8/1992 Rabi
`y
`ablin r
`5,157,242 10/1992 Hetherington et al... 219,553
`5,224,498 7/1993 Deevi et al..
`5,353,813 10/1994 Deevi et al. ............................ 219,543
`5,369,723 11/1994 Counts et al. .......................... 392/386
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 002
`
`

`

`U.S. Patent
`
`Mar 12, 1996
`
`Sheet 1 of 8
`
`5,498,855
`
`
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 003
`
`

`

`U.S. Patent
`
`Mar 12, 1996
`
`Sheet 2 of 8
`
`5,498,855
`
`
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 004
`
`

`

`U.S. Patent
`
`Mar 12, 1996
`
`Sheet 3 of 8
`
`5,498,855
`
`
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 005
`
`

`

`Philip Morris Products, S.A.
`Exhibit 1026
`Page 006
`
`

`

`U.S. Patent
`
`Mar 12, 1996
`
`Sheet 5 of 8
`
`5,498,855
`
`
`
`1014
`106
`104
`103
`102
`101
`100
`10-1
`10-2
`10-5
`10-4
`10-5
`10-6
`
`O
`
`10 20 30 40 50 60 70 80 90 100
`Wol. 6 of Conducting Material
`FIG. IO
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 007
`
`

`

`U.S. Patent
`
`Mar. 12, 1996
`
`Sheet 6 of 8
`
`5,498,855
`
`Fix Composition
`Electrical Resistivity
`Physical Properties
`
`
`
`
`
`
`
`intedrol Heoters
`
`
`
`
`
`
`
`
`
`Powder Processing
`Fix Composition, Binders,
`Sintering Aids, Surfactants,
`Rheological Fluids
`
`Milling
`Slip Preparation
`
`Forming Operation
`Hot Pressing, 1750°C,
`Cold isostolic Pressing/Pre-Sinter, 1100°C
`Slip Casting/Pre-Sinter, 1100°C
`
`
`
`
`
`
`
`Machining/Grinding
`Obtain Desired Shape
`Reduce O.D/.D
`
`Sintering
`Densification to 99% +
`Heot To 1800°C, 2 Hrs
`
`
`
`Finishing
`Diamond Grinding/Cutting
`Ultrasonic Machining
`Loser Machining
`
`integral Heaters
`
`F1 G 11
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 008
`
`

`

`U.S. Patent
`
`Mar 12, 1996
`
`Sheet 7 of 8
`
`5,498,855
`
`
`
`(O) SINIQIWAIGIAMAJ,
`
`
`
`
`
`
`
`
`
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`
`(r) Roxa Na
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 009
`
`

`

`U.S. Patent
`
`Mar 12, 1996
`
`Sheet 8 of 8
`
`5,498,855
`
`
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 010
`
`

`

`5,498,855
`
`1.
`ELECTRICALLY POWERED CERAMC
`COMPOSITE HEATER
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`This is a continuation-in-part of commonly assigned
`patent application Ser. No. 08/224,848, filed Apr. 8, 1994,
`which is a continuation-in-part of commonly assigned Ser.
`No. 08/118,665, filed Sep. 10, 1993, U.S. Pat. No. 5,388,
`594, which in turn is a continuation-in-part of commonly
`assigned patent application Ser. No. 071943,504, filed Sep.
`11, 1992. This also relates to commonly assigned Copending
`patent application Ser. No. 071943,747, filed Sep. 11, 1992
`and to commonly assigned U.S. Pat. No. 5,060,671, issued
`Oct. 29, 1991; U.S. Pat. No. 5,095,921, issued Mar. 17,
`1992; and U.S. Pat. No. 5,224,498, issued Jul. 6, 1992; all
`of which are hereby incorporated by reference.
`
`10
`
`15
`
`2
`weaker and may tear or break as they are removed from the
`lighter.
`U.S. patent application Ser. No. 08/118,665, filed Sep.10,
`1993, describes an electrical smoking system including a
`novel electrically powered lighter and novel cigarette that is
`adapted to cooperate with the lighter. The preferred embodi
`ment of the lighter includes a plurality of metallic sinusoidal
`heaters disposed in a configuration that slidingly receives a
`tobacco rod portion of the cigarette.
`The preferred embodiment of the cigarette of Ser. No.
`08/118,665 preferably comprises a tobacco-laden tubular
`carrier, cigarette paper overwrapped about the tubular car
`rier, an arrangement of flow-through filter plugs at a mouth
`piece end of the carrier and a filter plug at the opposite
`(distal) end of the carrier, which preferably limits air flow
`axially through the cigarette. The cigarette and the lighter
`are configured such that when the cigarette is inserted into
`the lighter and as individual heaters are activated for each
`puff, localized charting occurs at spots about the cigarette.
`Once all the heaters have been activated, these charred spots
`are closely spaced from one another and encircle a central
`portion of the carrier portion of the cigarette. Depending on
`the maximum temperatures and total energies delivered at
`the heaters, the charred spots manifest more than mere
`discolorations of the cigarette paper. In most applications,
`the charring will create at least minute breaks in the cigarette
`paper and the underlying carrier material, which breaks tend
`to mechanically weaken the cigarette. For the cigarette to be
`withdrawn from the lighter, the charred spots must be at least
`partially slid past the heaters. In aggravated circumstances,
`such as when the cigarette is wet or twisted, the cigarette
`may be prone to break or leave pieces upon its withdrawal
`from the lighter. Pieces left in the lighter fixture can interfere
`with the proper operation of the lighter and/or deliver an
`off-taste to the smoke of the next cigarette. If the cigarette
`breaks in two while being withdrawn, the smoker may be
`faced not only with the frustration of failed cigarette prod
`uct, but also with the prospect of clearing debris from a
`clogged lighter before he or she can enjoy another cigarette.
`The preferred embodiment of the cigarette of Ser. No.
`08/118,665 is essentially a hollow tube between the filter
`plugs at the mouthpiece end of the cigarette and the plug at
`the distal end. This construction is believed to elevate
`delivery to the smoker by providing sufficient space into
`which aerosol can evolve off the carrier with minimal
`impingement and condensation of the aerosol on any nearby
`surfaces. Ser. No. 08/118,665 also discloses an electrical
`smoking article having heaters which are actuated upon
`sensing of a draw by control and logic circuitry.
`Although these devices and heaters overcome the
`observed problems and achieve the stated objectives, many
`embodiments are plagued by the formation of a significant
`amount of condensation formed as the tobacco flavor
`medium is heated to form vapors. These vapors can cause
`problems as they condense on relatively cooler various
`electrical contacts and the associated control and logic
`circuitry. The condensation can cause shorting and other
`undesired malfunctions. In addition, condensation can influ
`ence the subjective flavor of the tobacco medium of the
`cigarette. Though not desiring to be bound by theory, it is
`believed that the condensation is the result of the flow
`pattern and pressure gradient of ambient air drawn through
`the article and the current designs of the heater assemblies.
`The proposed heaters are also subject to mechanical weak
`ening and possible failure due to stresses induced by insert
`ing and removing the cylindrical tobacco medium. In addi
`tion, the electrical smoking articles employ electrically
`resistive heaters which have necessitated relatively complex
`electrical connections which could be disturbed by insertion
`and removal of the cigarette.
`
`20
`
`25
`
`35
`
`40
`
`BACKGROUND OF THE INVENTION
`1. Technical Field of the Invention
`The present invention relates generally to electrically
`powered ceramic composite heaters for devices such as an
`electrical smoking article and more particularly to a tubular
`ceramic heater for use in an electrical smoking article.
`2. Discussion of the Related Art
`Previously known conventional smoking devices deliver
`flavor and aroma to the user as a result of combustion of
`tobacco. A mass of combustible material, primarily tobacco,
`30
`is oxidized as the result of applied heat with typical com
`bustion temperatures in a conventional cigarette being in
`excess of 800° C. during puffing. Heat is drawn through an
`adjacent mass of tobacco by drawing on the mouth end.
`During this heating, inefficient oxidation of the combustible
`material takes place and yields various distillation and
`pyrolysis products. As these products are drawn through the
`body of the smoking device toward the mouth of the user,
`they cool and condense to form an aerosol or vapor which
`gives the consumer the flavor and aroma associated with
`smoking.
`Conventional cigarettes must be fully consumed or be
`discarded once lit. A prior alternative to the more conven
`tional cigarettes include those in which the combustible
`material itself does not directly provide the flavorants to the
`aerosol inhaled by the smoker. In these smoking articles, a
`45
`combustible heating element, typically carbonaceous in
`nature, is combusted to heat air as it is drawn over the
`heating element and through a Zone which contains heat
`activated elements that release a flavored aerosol. While this
`type of smoking device produces little or no sidestream
`smoke, it still generates products of combustion, and once lit
`it is not adapted to be snuffed for future use in the conven
`tional sense.
`In both the more conventional and carbon element heated
`smoking devices described above combustion takes place
`during their use. This process naturally gives rise to many
`by-products as the combusted material breaks down and
`interacts with the surrounding atmosphere.
`Commonly assigned U.S. Pat. Nos. 5,093,894; 5,224,498;
`5,060,671 and 5,095,921 disclose various electrical resistive
`heating elements and flavor generating articles which sig
`nificantly reduce sidestream smoke while permitting the
`smoker to selectively suspend and reinitiate smoking. How
`ever, the cigarette articles disclosed in these patents are not
`very durable and may collapse, tear or break from extended
`or heavy handling. In certain circumstances, these prior
`cigarette articles may crush as they are inserted into the
`electric lighters. Once they are smoked, they are even
`
`50
`
`55
`
`60
`
`65
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 011
`
`

`

`10
`
`5
`
`20
`
`30
`
`25
`
`-3
`U.S. Pat. Nos. 5,060,671 and 5,093,894 disclose a number
`of possible heater configurations, many of which are made
`from a carbon or carbon composite material formed into a
`desired shape. In several of the disclosed configurations, the
`heater includes a plurality of discrete electrically resistive
`heating segments that can be individually activated to pro
`vide a single puff of flavor to the user. For example, one
`configuration involves a radial array of blades connected in
`common at the center and separately connectable at their
`outer edges to a source of electrical power. By depositing
`flavor-generating material on each blade and heating the
`blades individually, one can provide a predetermined num
`ber of discrete puffs to the user. Other configurations include
`various other arrays of discrete fingers or blades of heater
`material, or various linear and tubular shapes subdivided to
`provide a number of discrete heating areas. Such configu
`rations of discrete heating segments may allow for more
`efficient consumption of power and more efficient use of
`heater and flavor-generating material.
`It has proven difficult, however, to arrange suitable heater
`materials in the above-described configurations. A suitable
`heater material must exhibit, among other things, a resistiv
`ity sufficient to allow for rapid heating to operating tem
`peratures. It is also desirable that the heater resistance
`correspond to the energy density of the power source in
`order to minimize power consumption. Suitable heater mate
`rials of low mass, such as those described in the above
`incorporated patents, must generally also be of very low
`density, however, and thus are difficult to arrange in such
`discrete heater segment configurations. Such low density
`characteristics complicate, or make impossible, assembly of
`the configurations by simple, well-known manufacturing
`techniques. Even after successful manufacture, such con
`figurations are often unacceptably fragile for use within a
`flavor-generating article. These problems can be overcome
`to some extent with the aid of highly sophisticated manu
`35
`facturing techniques. However, in manufacturing the heaters
`which are disposable and replaceable, these techniques .
`become prohibitively expensive.
`It would thus be desirable to provide a discrete heater
`configuration of suitable heater material that is sufficiently
`strong for use within a flavor-generating article without
`threat of breakage during manufacture. It would also be
`desirable to be able to manufacture such a heater with a
`discrete heater segment configuration using well-known,
`inexpensive manufacturing techniques.
`Various ceramic heating compositions are described in
`U.S. Pat. Nos. 5,045,237 and 5,085,804. Also, British Patent
`No. 1,298,808 and U.S. Pat. Nos. 2,406.275; 3,875,476;
`3,895.219; 4,098,725; 4,110,260; 4,327,186; and 4,555,358
`relate to electrically conductive ceramic heater materials.
`SUMMARY OF THE INVENTION
`The invention provides an electrically powered ceramic
`composite heater useful for devices such as an electric
`flavor-generating article. The heater includes an annular
`hub, with a central axis, a plurality of electrically conductive
`blades, attached to the hub and extending from its perimeter
`in one direction parallel to the hub's central axis. Each of the
`blades has a free end remote from the hub. The hub and the
`blades form a hollow cylinder and the hub and blades
`comprise a monolithic electrically resistance heating
`ceramic material.
`According to one aspect of the invention, the hub and the
`blades comprise a sintered mixture comprising an insulator
`or semiconductive metal compound A and an electrically
`conductive metal compound B, compounds A and B being
`present in amounts effective to provide a resistance of the
`ceramic material which does not change by more than 20%
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`5,498,855
`
`4.
`throughout a heating cycle between ambient temperatures
`and 900° C. Compound Acan have a negative temperature
`coefficient of resistivity and compound B can have a positive
`temperature coefficient of resistivity. Compound A can con
`prise one or more compounds selected from the group
`consisting of SiN. Al2O, ZrO2, SiC and B4C. Compound
`B can comprise one or more compounds selected from the
`group consisting of TiC, MoSi, TiSi, ZrSi, ZrB, and
`TiB. Compound A can be present in an amount of 45-80
`vol.% and compound B is present in an amount of 20-55
`vol. 96. The ceramic material can further comprise a rein
`forcing agent such as fibers or whiskers of SiC, SiN, SiCN,
`SiAION. The ceramic material can be SiN based and
`include MoSi, SiC and/or TiC additions. For instance, the
`ceramic material can include in volume 9% of 55 to 80%
`SiN, up to 35% MoSi, up to 20%. SiC and up to 45%. TiC
`or in volume % of 55 to 65%. SiN, 15 to 25% MoSi and
`5 to 15%. SiC.
`The heater can have a number of desirable features. For
`instance, the ceramic material preferably heats to 900° C. in
`less than 1 second when a voltage of up to 10 volts and up
`to 6 amps is passed through the ceramic material. The
`ceramic material also preferably exhibits a weight gain of
`less than 4% when heated in air to 1000 C. for three hours.
`Each of the blades can have a resistance (R) of 0.05 to 7
`ohms, a length (L), a width (W), and a thickness (T), and the
`ceramic material has a resistivity (p), the blade dimensions
`being in accordance with the formula R=p(L/(WXT)). Each
`of the blades can have an electrical resistance of about 0.6
`to 4 ohms throughout a heating cycle between ambient and
`900° C.
`When the heater is used in a flavor-generating device, the
`device can include a portable energy device electrically
`connected to the blades. The portable energy device can
`have a voltage of about 3 to 6 volts. In this case, each of the
`blades preferably has an electrical resistance of about 1 ohm
`throughout a heating cycle between ambient and 900 C.
`The heater hub can act as the common and/or negative
`electrical contact for all of the blades. Part or all of the
`blades and/or hub preferably include a coating of a brazing
`material suitable for joining ceramic material and electrical
`leads are preferably connected to the blades by the brazing
`material. A metal cage comprising a hub and blades can be
`fitted against the heater hub such that the cage blades extend
`between the heater blades with air gaps having a width of
`about 0.1 to 0.25 mm being located between opposed edges
`of the cage blades and the heater blades.
`According to one aspect of the invention, the heater is
`electrically connected to a lead pin module having leads
`electrically connected to the heater blades. The heater hub
`includes at least one air passage therethrough. The free ends
`of the heater blades are supported by a lead pin module
`having leadpins electrically connected to the free ends of the
`heater blades, the heater hub being open and defining a
`cavity which extends along the heater blades and the cavity
`being sized to receive a cigarette containing flavor generat
`ing material. The device can further include puff sensing
`means and electrical circuit means for supplying electrical
`current to one of the heater blades in response to a change
`in pressure when a smoker draws on a cigarette surrounded
`by the heater blades. For instance, each of the blades can
`have a free end remote from the hub functioning to electri
`cally connect the blade to a power and control module of the
`flavor-generating article with the hub and blades comprising
`a monolithic electrically resistance heating ceramic material.
`The flavor-generating material is disposed in proximity to
`the blades so as to be heated by the blades.
`The invention also provides a method of making an
`electrically powered ceramic composite heater useful for
`devices such as an electric flavor-generating article. The
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 012
`
`

`

`5,498,855
`
`S
`method includes forming a ceramic material into a mono
`lithic shape such as a plurality of longitudinally extending
`and circumferentially spaced-apart blades extending from
`one end of a cylindrical hub portion and sintering the
`ceramic material. The forming step can include extruding
`the ceramic material to form a tube having a plurality of
`channels extending longitudinally along the inside surface of
`the tube, removing (by a process such as grinding) an outer
`periphery of the tube at longitudinally spaced apart locations
`until the channels are exposed and a plurality of the longi
`tudinally extending blades are formed, the blades extending
`between hub portions of the tube, and separating each hub
`portion from an adjacent set of blades such that each hub
`portion includes blades extending from only one axial end of
`the hub portion. The separating step can be carried out by
`laser cutting the tube such that one end of a group of blades
`is separated from an adjacent hub portion.
`The ceramic material can be prepared in various ways.
`For instance, the raw ingredients can be mixed with a
`sintering additive prior to the extrusion step. The ceramic
`material can be prepared by mixing elements which react
`during the sintering step to form the insulator metal com
`20
`pound A or the electrically conductive metal compound B.
`For instance, the ceramic material can be prepared by
`mixing Mo, C and Si, the Mo, C and Si forming MoSi and
`SiC during the sintering step. The ceramic material can be
`prepared by mechanical alloying or by mixing prealloyed
`powder comprising at least one material selected from the
`group consisting of SiN, Al2O3, ZrO2, SiC., BC, TiC,
`MoSi2, TiSi, ZrSi, ZrB, TiB, TiN and SiN.
`The ceramic material can be sintered and/or presintered in
`various ways. For instance, the ceramic material can be
`presintered prior to the removing step, sintered by hot
`isostatic pressing or subjected to a temperature of 1100° C.
`or higher during the extrusion step whereby the ceramic
`material can be sintered during the extrusion step.
`The invention also provides an electrically resistance
`heating ceramic material comprising an insulator or semi
`conductive metal compound A and an electrically conduc
`tive metal compound B, compounds A and B being present
`in amounts effective to provide a resistivity of about 0.0008
`to 0.01 Q-cm-20% throughout a heating cycle between
`ambient and 900° C. For instance, compound A can com
`prise one or more compounds selected from the group
`consisting of SiN. Al-O, ZrO2, SiC and BC and com
`pound B can comprise one or more compounds selected
`from the group consisting of TiC, MoSi, TiSi, ZrSi, ZrB
`and TiB2. Compound A can be present in an amount of
`45-80 vol.% and compound B can be present in an amount
`of 20-55 vol. 9%.
`The electrically resistance heating ceramic material pref
`erably heats to 900° C. in less than 1 second when a current
`of up to 10 volts and up to 6 amps or less than 30 joules is
`passed through the electrically resistance heating ceramic
`material. The electrically resistance heating ceramic mate
`rial preferably exhibits a weight gain of less than 4% when
`heated in air to 1000 C. for three hours. The electrically
`resistance heating ceramic material can further comprise a
`55
`reinforcing agent, such as fibers or whiskers of SiC, SiN,
`SiCN or SiAlON. Compound A can have a negative tem
`perature coefficient of resistivity and compound B can have
`a positive temperature coefficient of resistivity. According to
`preferred embodiments of the ceramic composition, the
`ceramic material can include in volume 96 of 55 to 80%
`SiN, up to 35% MoSi, up to 20% SiC and up to 45% TiC
`or in volume % of 55 to 65% SiN, 15 to 25% MoSi and
`5 to 15% SiC.
`BRIEF DESCRIPTION OF THE DRAWINGS
`The invention is described in conjunction with the accom
`panying drawings, in which like reference numerals refer to
`
`30
`
`6
`like parts throughout, and in which:
`FIG. 1 is a perspective view of an electrical smoking
`article which utilizes an electrically powered ceramic com
`posite heater in accordance with the present invention;
`FIG. 2 is an exploded view of the device shown in FIG.1;
`FIG.3 is a perspective view of a ceramic heater assembly
`in accordance with the present invention;
`FIG. 4 is a perspective view of a monolithic ceramic
`heater in accordance with the present invention;
`FIG. 5 is a perspective view of an electrically conducting
`metal cage in accordance with the present invention;
`FIG. 6 is a perspective view of a fixture in accordance
`with the present invention;
`FIG. 7 is a perspective view of a retainer ring in accor
`dance with the present invention;
`FIG. 8 is a perspective view of a pin module in accordance
`with the present invention;
`FIG. 9 is a perspective view of a segment of a precursor
`of the heater of FIG. 4;
`FIG. 10 shows a graph of electrical resistivity vs. vol.%
`conducting material of a ceramic composite material in
`accordance with the invention;
`FIG. 11 shows a flow chart of processing steps which can
`be used to make a ceramic heater in accordance with the
`invention;
`FIG. 12 shows a typical plot of temperature vs. energy for
`composition No. 8 in Table 5;
`FIGS. 13a-c show perspective views of components of a
`heater assembly according to another embodiment of the
`invention; and .
`FIG, 14 shows an assembly of the components shown in
`FIGS. 13-c.
`
`DETALED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`A smoking system 1 according to the present invention is
`generally seen with reference to FIGS. 1 and 2. The smoking
`system 1 includes a cylindrical aerosol generating tube or
`cigarette 2 and areusable lighter 3. The cigarette 2 is adapted
`to be inserted in and removed from an orifice 4 at a frontend
`5 of the lighter 3. The smoking system 1 is used in much the
`same fashion as a conventional cigarette. The cigarette 2 is
`disposed of after one or more puff cycles and a preferred
`cigarette construction described in commonly assigned and
`copending Ser. No. 08/118,665 is hereby incorporated by
`reference. The lighter 3 is preferably disposed of after a
`greater number of puff cycles than the cigarette 2.
`The lighter 3 includes a housing 6 and has front and rear
`portions 7 and 8. A power source 9 for supplying energy to
`heating elements for heating the cigarette 2 is preferably
`disposed in the rear portion 8 of the lighter 3. The rear
`portion 8 is preferably adapted to be easily opened and
`closed, such as with screws or with snap-fit components, to
`facilitate replacement of the power source 9. The front
`portion 7 preferably houses heating elements and circuitry in
`electrical communication with the power source 9 in the rear
`portion 8. The front portion 7 is preferably easily joined to
`the rear portion 8, such as with a dovetail joint or by a socket
`fit. The housing 6 is preferably made from a hard, heat
`resistant material. Preferred materials include metal-based
`or more preferably, polymer-based materials. The housing 6
`is preferably adapted to fit comfortably in the hand of a
`Smoker and, in a presently preferred embodiment, has over
`all dimensions of 10.7 cm by 3.8 cm by 1.5 cm.
`The power source 9 is sized to provide sufficient power
`for heating elements that heat the cigarette 2. The power
`
`10
`
`15
`
`25
`
`35
`
`45
`
`50
`
`60
`
`65
`
`Philip Morris Products, S.A.
`Exhibit 1026
`Page 013
`
`

`

`5,498,855
`
`O
`
`15
`
`7
`source 9 is preferably replaceable and rechargeable and may
`include devices such as a capacitor, or more preferably, a
`battery. In a presently preferred embodiment, the power
`source is a replaceable, rechargeable battery such as four
`nickel cadmium battery cells connected in series with a total,
`non-loaded voltage of approximately 4.8 to 5.6 volts. The
`characteristics required of the power source 9 are, however,
`selected in view of the characteristics of other components
`in the smoking system 1, particularly the characteristics of
`the heating elements. U.S. Pat. No. 5,144,962 describes
`several forms of power sources useful in connection with the
`smoking system of the present invention, such as recharge
`able battery sources and quick-discharging capacitor power
`sources that are charged by batteries, and is hereby, incor
`porated by reference.
`A substantially cylindrical heater assembly 10 (see FIG.
`3) for heating the cigarette 2, and, preferably, for holding the
`cigarette in place relative to the lighter 3, and electrical
`control circuitry 11 for delivering a predetermined amount
`of energy from the power source 9 to heating elements (not
`seen in FIGS. 1 and 2) of the heater assembly are preferably
`disposed in the front 7 of the lighter. As described in greater
`detail below, a generally circular, monolithic ceramic heat
`ing element 20, as shown in FIG.4, is fixed, e.g., brazed or
`welded, to be disposed within the interior of heater assembly
`10. The heater element 20 includes a hub 21 and a plurality
`of longitudinally extending and circumferentially spaced
`apart blades 22. The heater preferably has only one end hub
`but other designs can be used. For instance, the heater could
`include two end hubs with the blades extending therebe
`tween. Further, the blades can have a non-linear configura
`tion.
`In the presently preferred embodiment, the heater element
`20 includes a plurality of spaced apart rectilinear heating
`blades 22 extending from the hub 21, seen in FIG. 4 and
`described in greater detail below, that are individually ener
`gized by the power source 9 under the control of the circuitry
`11 to heat a number of, e.g., eight, areas around the periphery
`of the inserted cigarette 2. Eight heating blades. 22 are
`preferred to develop eight puffs as in a conventional ciga
`rette and eight heater blades also lend themselves to elec
`trical control with binary devices. However, any desired
`number of puffs can be generated, e.g., any number between
`5-16, and preferably 6-10 or 8 per inserted cigarette and the
`number of heating blades can exceed the desired number of
`puffs/cigarette.
`The circuitry 11 is preferably activated by a puff-actuated
`sensor 12, seen in FIG. 1, that is sensitive to pressure drops
`that occur when a smoker draws on the cigarette 2. The
`puff-actuated sensor 12 is preferably disposed in the front 7
`of the lighter 3 and communicates with a space inside the
`heater fixture 10 and near the cigarette 2. A puff-actuated
`sensor 12 suitable for use in the smoking system 1 is
`described in U.S. Pat. No. 5,060,671, the disclosure of which
`is incorpora