Volatile carrier for use with a heating device

A volatile carrier for supplying a volatile ingredient to a heating device to be dispensed thereby, the heating device having a heat transfer site and a pass-through path to receive an inserted volatile carrier at one end of the pass-through path to position the volatile carrier adjacent to the heat transfer site. The volatile carrier has a substantially unitary reservoir block containing a supply of the volatile ingredient. The reservoir block is greater in size than the heat transfer site. An advancement device is supplied by which a user can manually advance the reservoir block past the heat transfer site to expose different portions of the reservoir block to heat. A method of supplying a volatile ingredient to such a heating device by use of such a volatile carrier is also described.

BACKGROUND OF THE INVENTION 
This invention relates to vapor releasing devices. More particularly, it 
relates to devices and methods for supplying vaporizable materials to a 
heater to allow the materials to be dispensed into the air. 
It is well known to provide vapor releasing materials from mats and other 
carriers that are positionable in a heating device so as to cause the 
materials to vaporize. See e.g. Martens, III. et al., U.S. Pat. No. 
4,849,606 (The disclosures of U.S. Pat. No. 4,849,606 and all other 
patents and patent applications referred to herein are incorporated by 
reference). These devices are effective for dispensing various volatile 
materials, including such materials as insect control active ingredients 
and scents for room freshening. Typically, the carriers must replaced from 
time to time to renew the source of volatile material. In many 
applications, it is desirable to extend the useful life of carriers so as 
to extend the time before replacement is necessary. 
In addition, there are many insect control heating devices that have been 
and are being marketed that are designed to accept conventional mats 
loaded with mosquito or other insect control materials. Many of these 
devices have a containing well, trough, or chamber that the mat slides 
into to be held over a hot surface or other source of heat. The exact size 
and shape of these containing structures differ somewhat from device to 
device. Thus, it would be desirable not only to have a volatile ingredient 
carrier having an extended useful life but also one that can fit securely 
into chambers of differing sizes. 
Addressing the need for extended life, Petrillo, French Pat. No. 2,547,735 
discloses a dispensing system that utilizes a series of connected tablets. 
The tablets are sequentially moved over a heater, with the next tablet 
moved over the heater when the previous tablet has been used up. 
Unfortunately, this dispensing system has an indexing system that is 
costly to manufacture and that is restricted to use with specifically 
designed heater openings. Other systems rely on reel-to-reel tape systems 
that also can be costly and are limited to specifically designed heating 
devices. There are many examples of such tape systems, but see, as one 
example, Japanese Pat. Appl. No. JP 1-210488, which also allows a user to 
select between different volatile materials. Zobele and Pedrotti, WO 
96/28970 provides a polymer block that is treated with insecticide and 
held within a frame. The block can carry sufficient insecticide to last 
for a considerable period of time. 
To obtain a long-lasting source of vaporizable active ingredient, other 
products provide for a wick that delivers a liquid vaporizable material 
from a reservoir to a heater. See, for example, Zobele et al., U.S. Pat. 
No. 5,095,647, and Schimanski et al., U.S. Pat. No. 5,222,186. A 
commercially available heater device manufactured by Zobele Industrie 
Chimiche S.P.A., Italy, as Zobele heater model SCJ-009 has a vertical 
passage extending through a heated ceramic block. S. C. Johnson & Son, 
Inc. of Racine, Wisconsin, sells a volatile supplier for this heater 
device that has a bottle containing a liquid insect control preparation, 
the bottle having an upwardly extending wick that fits through the 
heater's vertical passage when the bottle is attached to the underside of 
the heater device. This arrangement is effective but does require the use 
of liquid, which is subject to spilling and the like. In contrast, the 
volatilizing device shown in Martens, III. et al., U.S. Pat. No. 4,849,606 
heats a volatilizable gel contained within a plastic tray that is closed 
with a volatiletransmitting membrane. 
A need exists for improved devices and methods for supplying providing 
vaporizable materials to heaters. 
BRIEF SUMMARY OF THE INVENTION 
In one aspect, the invention provides a volatile carrier for supplying a 
volatile ingredient to a heating device to be dispensed thereby. The 
heating devices with which use of the volatile carrier is intended are of 
the kind that have a heat transfer site and a pass-through path to receive 
a volatile carrier inserted at one end of the pass-through path to 
position the volatile carrier adjacent to the heat transfer site. Heat in 
these devices may be generated electrically, by flaming or catalytically 
combusted fuel, or by any other of the ways known to those skilled in the 
art to provide heat in such devices. Such heating devices commonly are 
used for dispensing air quality modifying materials such as perfumes, 
insect control ingredients, and any other volatile material to be 
dispensed, if the material is capable of withstanding the temperatures of 
such a device. "Volatile ingredient" is defined to include all such 
materials. "Insect control ingredient" includes materials that kill 
insects as well as those that otherwise affect their biological functions 
or behavior, including bpt not limited to insecticides, insect repellents, 
and insect growth inhibitors. 
The volatile carrier of the invention includes a substantially unitary 
reservoir block containing a supply of the volatile ingredient to be 
dispensed. The term "block" is not intended to connote any particular 
shape. Instead, "block" includes any substantially unitary mass of 
non-flowable material, including fibrous mats, non-flowing gels, plastic 
or other solid materials, and the like. A reservoir block is defined to be 
"substantially unitary" if it is a mass of material functionally 
uninterrupted with respect to the release of volatile ingredients, even if 
the block is made up of sections that, while they are closely grouped and 
preferably at least abut each other, are not joined into an unbroken 
monolith of material. But preferably, the reservoir block is a single, 
undivided block of material and most preferably is made of a polymer 
capable of receiving the volatile ingredient and releasing it when 
subjected to the heat of the heating device. However, other convenient 
materials formable into blocks and suitable as substrates for the heated 
release of volatile ingredients may be used instead. Preferably, the 
reservoir block does not deform as a consequence of its being handled 
during use. The reservoir block also may be made of materials that consume 
as the volatile ingredient is released. 
The reservoir block of the invention is greater in size than the heat 
transfer site of the heating device with which it is to be used. The 
invention includes an advancement device by which a user can manually 
advance the reservoir block past the heat transfer site to expose 
different portions of the reservoir block to heat. 
Different selected regions of the reservoir block can carry different 
volatile ingredients, different concentrations of the same volatile 
ingredient, or combinations of such variations. This allows a user to use 
a single volatile carrier and, by using the advancement device, to 
position a selected portion of the reservoir block by the heat transfer 
site to select among differing volatile ingredients or delivery amounts or 
rates. For example, a high concentration insect control ingredient can be 
useful at night, when mosquito activity is high, and a lower 
concentration, a different insect control ingredient, or only a scent may 
be appropriate during the day. 
Preferably, the advancement device of the volatile carrier provides a 
signal to a user that correlates with movement of the reservoir block as 
the reservoir block is moved past the heat transfer site. The signal can 
be a click or other noise, a tactile signal such as that a user can feel 
when the resistance of a detent is overcome by manually manipulating a 
moving part, or a visual signal such as the appearance of different 
colored materials as they are moved behind a window or the appearance of a 
line or other visual indicia or indicator that is moved or distinctively 
aligned. Other signals will be apparent to those skilled in the art and 
fall within the breadth and scope of the invention. Preferably, movement 
of the reservoir block is by discrete increments, most preferably with 
each incremental movement accompanied by such a signal. 
In one aspect of the invention, the advancement device includes a frame 
that holds the reservoir block. Preferably, the frame has a handle by 
which a user can manipulate the volatile carrier and is sufficiently 
flexible to follow slight bends in a pass-through path. 
Many heating devices for dispensing volatile ingredients are so designed as 
to allow a volatile carrier to be inserted in one end of a pass-through 
path and to exit the heating device at the other end of the pass-through 
path. Also, independent of the exiting feature just mentioned, heating 
devices exist that employ enclosed passages, tunnels, or chambers; open 
troughs; or other arrangements as the pass-through path, the lateral 
dimensions of such pass-through paths typically being defined by path 
sides. In another aspect of the invention, the volatile carrier of the 
invention especially suited to such heating devices includes a 
longitudinally extended frame having a plurality of resilient fingers that 
extend distally from the frame to engage a path side to position the frame 
with respect to the path side and the heat transfer site. Preferably, 
resilient fingers extend from the frame to engage opposed path sides. 
Preferably, the fingers slant at an angle away from the intended direction 
of travel of the volatile carrier through the pass-through path to favor 
movement of the volatile carrier in only the intended direction. In a 
further aspect of the invention, the frame includes a stop tab that 
extends distally from the frame sufficiently far to restrict and 
preferably even prevent the volatile carrier from entering the 
pass-through path of the heater device beyond the location of the stop 
tab. This arrangement, when combined with the slanted fingers just 
described, favors movement of the volatile carrier one way through the 
pass-through path until the volatile carrier is stopped and held by the 
stop tab, whereupon accidental or unintentional release of the volatile 
carrier from the heater device is discouraged. However, the stop tab 
preferably is manually bendable in a proximal direction sufficiently far 
to allow a user to intentionally move the volatile carrier on through the 
pass-through path. The stop tabs may be either resilient or not, as 
desired, and may be lockable in place when bent to a proximal location. 
Resilient but lockable stop tabs are preferred. 
In another aspect of the invention, the volatile carrier described is 
particularly suited for use with a heater device whose pass-through path 
has a pinch point of a given width and thereafter either opens to a wider 
dimension or ends in an open exit. It is preferred that the fingers of the 
volatile carrier extend sufficiently distally that the fingers engage a 
path side at the pinch point to require the fingers to bend proximally, 
bending away from the direction of movement of the volatile carrier 
through the pass-through path. The fingers then resiliently spring 
distally after passing the pinch point. 
If, as is preferred, the fingers are longitudinally spaced along the frame 
and are sufficiently resilient and stiff that a user can hear audible 
clicks as successive fingers resiliently spring back distally after 
passing the pinch point, this effect provides a signal to the user that 
corresponds to incremental movement of the reservoir block past the heat 
transfer site. 
As has been previously mentioned, some existing heating devices have a 
pass-through path that is a passage extending upwardly through a heated 
block of ceramic or other material. An embodiment of the invention 
especially useful with such heating devices, but also with other 
arrangements where a heating device is so designed as to allow the 
reservoir block to exit the heating device at the other end of the 
pass-through path, includes a longitudinally extended reservoir block, 
preferably made of a material that can resist deformation, at least to the 
extent necessary to avoid the reservoir block's deforming and jamming as 
it passes through the pass-through path. A block container is secured to a 
first end of the reservoir block, the block container being attachable to 
the heater device, with a second end of the reservoir block aligned with 
and insertable into the pass-through path. The reservoir block is designed 
to be movable with respect to the block container to advance the reservoir 
block past the heat transfer site. 
Preferably the block container includes a shell that attaches to the heater 
device and a manually operable block advancer that a user can operate to 
advance the reservoir block into the pass-through path. To achieve this, 
the block advancer can include a block holder that operates on the first 
end of the reservoir block and is slidably engaged with the shell so that, 
when a user slides the block holder relative to the shell, the reservoir 
block moves past the heat transfer site. In another and preferred 
arrangement, the block advancer is operated by a user by rotating a knob 
or other rotatable part that is rotatably engaged with the shell such 
that, when a user turns the rotatable part, the reservoir block is moved 
relative to the heat transfer site. 
In any event, preferably the block advancer provides a signal to a user 
that corresponds to movement of the reservoir block as the reservoir block 
is advanced past the heat transfer site. For example, when the block 
advancer has a knob or other rotatable part that is turned to move the 
reservoir block, it is preferred to provide a detent mechanism that 
overcomeably resists movement of the rotatable part as it is turned in 
successive, incremental amounts to provide a click or a tactile signal of 
an incremental movement of the reservoir block. 
When a rotatable part arrangement is used, the block advancer preferably 
includes a threaded shaft rotatably engaged but longitudinally fixed with 
respect to the shell, and a nut longitudinally fixed with respect to the 
reservoir block and threadably engaged with the threaded shaft. When the 
threaded shaft is rotated with respect to the nut, the reservoir block is 
moved longitudinally relative to the shell to move past the heat transfer 
site. Alternatively, the reverse arrangement can be used, wherein the 
block advancer includes a nut rotatably engaged but longitudinally fixed 
with respect to the shell, and a threaded shaft longitudinally fixed with 
respect to the reservoir block and threadably engaged with the nut. When 
the nut is rotated with respect to the threaded shaft, the reservoir block 
will move longitudinally relative to the shell. 
The method of the invention of supplying a volatile ingredient to be 
dispensed by heating devices of the sort referred to above includes the 
steps of supplying a volatile carrier as described above and moving the 
reservoir block past the heating device's heat transfer site. When a 
reservoir block is provided having regions carrying different volatile 
ingredients, the step of moving the reservoir block past the heating 
device's heat transfer site can include the steps of selecting a region of 
the reservoir block carrying a desired volatile ingredient and moving that 
region to the heat transfer site. The method may further include the step 
of successively moving different selected regions of the reservoir block 
to the heat transfer site to cause the heating device successively to emit 
different volatile ingredients. 
When a reservoir block is provided having regions carrying different 
concentrations of the same volatile ingredient, the step of moving the 
reservoir block past the heating device's heat transfer site can include 
the steps of selecting a region of the reservoir block carrying a desired 
concentration of the volatile ingredient and moving that region to the 
heat transfer site to cause the heating device to emit a selected amount 
of the volatile ingredient. The method may further include the step of 
successively moving different selected regions of the reservoir block to 
the heat transfer site to cause the heating device successively to emit 
differing amounts of the volatile ingredient.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning now to the drawings, wherein like reference numbers refer to like 
and corresponding parts throughout the several views, a first embodiment 
of the volatile carrier of the invention is shown generally at 10 in FIG. 
1. The volatile carrier 10 is shown positioned beside a conventional 
heating device, shown generally at 12. 
Heating devices for vaporizing volatile ingredients are well known as are, 
specifically, heating devices that volatilize insect control ingredients 
from fiber mats or liquid-bearing wicks. The conventional heating device 
12 corresponds generally to the commercially available heater model 
SCJ-009 made by Zobele Industrie Chimiche S.P.A., Italy, and sold by S. C. 
Johnson & Son, Inc., of Racine, Wisconsin. The SCJ-009 device is preferred 
for use with the specific embodiments of the invention described below, 
but the invention is in no way limited to use with the SCJ-009 device. To 
the contrary, the volatile carrier 10 is designed to be flexibly usable 
with a variety of mat or wick-type heating devices, serving as an 
alternative to conventional mat or liquid-bearing wick arrangements. 
The heating device 12 is designed to be plugged into an electrical 
receptacle. Heat is generated by a resistance or other electrical heater 
(not shown) that is located within a ceramic block (best seen at 13 in 
FIG. 6 in conjunction with a second embodiment of the volatile carrier, 
yet to be discussed). The ceramic block 13 becomes hot when the heating 
device is energized. The top surface 14 (seen in FIG. 3) of the ceramic 
block 13 is exposed and is adapted to receive a mat or other carrier of 
volatile ingredients to be dispensed. The top surface 14 serves as a heat 
transfer site, the site at which heat is transferred to a mat or other 
volatile-holding carrier. In general, all conventional heating devices of 
this sort make provision for the transfer of heat from some heat source to 
the mat or other volatile-holding carrier used with the heating device. 
The location of that heat transfer typically is limited in size by use of 
a heated plate or passageway, a grid of a selected dimension placed over a 
catalytic heater, or the like. The term "heat transfer site" as used 
herein refers to the location of heat transfer and is referred to as 
having an essentially fixed area. 
The heating device 12 is also typical of many conventional heating devices 
in that it has a body 16 having a pass-through path 18 having path sides 
20. Commonly, a mat or other conventional volatile-holding carrier is 
inserted in or on the heating device, to slide into the device until the 
carrier reaches the heat transfer site. A common arrangement is to replace 
a spent mat, for example, by moving it on out of the heating device, 
pushing it with a new, fresh mat. The pass-through path defines the route 
followed through the heating device 12 by such a mat or other 
volatile-holding carrier, and the path sides 20 serve as guides, ensuring 
that the carrier is properly located at the heat transfer site. 
The pass-through path 18 of the heating device 12 allows insertion of a mat 
from the side of the heating device under a protective grid 22, with spent 
mats being pushed out of the opposite side of the heating device when a 
fresh mat is inserted in the pass-through path. The heating device 12 may 
also be equipped with alternative pass-through paths, such as the vertical 
passage shown at 42 in FIG. 6 and discussed below. 
The volatile carrier 10 has a substantially unitary reservoir block 24 (as 
"substantially unitary" and "block" are defined, above) containing a 
supply of a volatile ingredient. The reservoir block 24 is longitudinally 
extended and is greater in size than the heating device's that transfer 
site. The reservoir block 24 preferably is composed of a 
polyether-polyamide copolymer obtained through the linear regular 
polymerization of polyether segments alternated with polyamide segments. 
Such compounds have excellent chemical and mechanical properties for this 
application and are available on the market under various commercial 
names. This material is preferred in part because its mechanical 
characteristics allow it to be formed into a variety of useful shapes by 
casting, extrusion, injection molding, sheet casting, or other 
conventional forming methods. 
Polyether-polyamide copolymer materials can be impregnated with insect 
control or other volatile ingredients by placing them in an appropriate 
solution of the volatile ingredients. See Pedrotti, EP 671,123 regarding 
techniques for forming such volatile releasing substrates for use with 
heaters. By selecting various relative percentages of the polyether and 
polyamide fractions of the copolymer, one can select for different 
volatile ingredient loading and retention characteristics. 
Insect control ingredients are the preferred volatile ingredients. 
Different regions of the reservoir block 24 can be treated with differing 
concentrations of ingredient or with different ingredients. Useful insect 
control ingredients include but are not limited to organo phosphorous 
insecticides, lipidamide insecticides, natural repellents such as 
citronella oil, natural pyrethrums and pyrethrum extract, and synthetic 
pyrethroids. The synthetic pyrethroid esbiothrin is particularly 
preferred, used with a polymeric reservoir block made of the 
polyether-polyamide copolymers known commercially as Pebax 4033 and Pebax 
3533 (available from Zobele Industrie Chimiche S.P.A.). 
The volatile carrier 10 includes a handle 26 that serves as an advancement 
device by which a user can manually advance the reservoir block 24 past 
the heat transfer site of the heating device 12. By using the handle 26, a 
user can move selected parts of the reservoir block 24 to the heat 
transfer site to expose different portions of the reservoir block to heat. 
The volatile carrier 10 has a frame 28 that holds the reservoir block, the 
handle 26 preferably being a part of the frame. Preferably, as in the 
embodiment shown at 10, the frame 28 is longitudinally extended and has a 
plurality of resilient fingers 30. The resilient fingers 30 extend 
distally from the frame, preferably extending sidewardly from at least one 
and preferably from two opposite sides of the frame. 
Whether located on only one side or on opposite sides of the frame 28, the 
resilient fingers 30 are sufficiently long to engage at least one and 
preferably opposing path sides 20 of the pass-through path 18 of a heating 
device 12. The resilient fingers 30 thus position the frame 28 within the 
pass-through path 18. Because the fingers 30 are resilient, they can 
operate within pass-through paths of different heating devices, flexing to 
fit various path widths and to move past indentations and projections that 
may exist within such pass-through paths. 
Preferably, as in the volatile carrier shown at 10, the resilient fingers 
30 slant at an angle away from the intended direction of travel of the 
volatile carrier through a pass-through path. This arrangement favors 
movement of the volatile carrier in only the intended direction. 
The pass-through path 18 of heater device 12 has a pinch point 32 of a 
given, constrained width and thereafter opens to a wider dimension. In 
other conventional heater devices, the pass-through path may be all of one 
width, making the entire length of the path the "pinch point" that opens 
to a wider dimension simply by ending with an exit. The resilient fingers 
30 extend sufficiently distally that the fingers engage a path side 20 at 
the pinch point 32, requiring the fingers to bend proximally, toward the 
frame 28, in a direction slanting away from the direction of movement of 
the volatile carrier 10 through the pass-through path. Once past the pinch 
point 32, the fingers 30 resiliently spring back distally. 
The fingers 30 of the preferred embodiment shown are longitudinally spaced 
along the frame 28 and are sufficiently resilient and stiff that a user 
can hear audible clicks or feel tactile impulses as successive fingers 
spring distally as they pass the pinch point. As a result, the user 
receives a signal that corresponds to incremental movement of the 
reservoir block 24 past the heat transfer site. 
Preferably, as in the embodiment shown, at least one and preferably two 
stop tabs 34 extend distally from the frame 28, preferably generally at 
the location of the handle 26 and preferably slanting in the intended 
direction of travel of the volatile carrier 10. The stop tabs 34 extend 
distally from the frame 28 sufficiently far to prevent the volatile 
carrier 10 from entering the pass-through path 18 beyond the location of 
the stop tabs. A user can pinch the stop tabs 34 inwardly, bending them 
proximally sufficiently to allow a user to intentionally move the volatile 
carrier 10 on through the pass-through path 18. Preferably the stop tabs 
34 either non-resiliently bend or lock in the bent position with a width 
narrower than the narrowest pinch point of the pass-through path 18 to 
allow the volatile carrier 10 to freely pass from the heating device 12. 
In the preferred embodiment shown, the distal ends of the stop tabs 34 
contact an engaging surface 36 and lock in their bent position. 
A second embodiment of the volatile carrier of the invention is shown 
generally at 38 in FIG. 5. The second embodiment 38 is shown in FIG. 4 in 
use with heating device 40, which is generally comparable to the heating 
device 12, described above. Corresponding parts of heating devices 12 and 
40 will be given the identical reference numbers and will not be discussed 
separately. Heating device 40 differs from heating device 12 in that the 
ceramic block 13 has a generally vertical passage 42 extending 
therethrough, the body 16 having an entrance port 44 (visible in FIG. 6) 
directly beneath the passage and the grid 22 having a corresponding exit 
port 46 (shown in FIG. 4) directly above the passage. The passage 42 can 
be used as a pass-through path, with the walls of the passage within the 
ceramic block 13 being the heat transfer site. The passage 42 as described 
is a pass-through path that can receive a reservoir block inserted at one 
end, with the heating device 40 being so designed as to allow the 
reservoir block to exit the heating device at the other end of the 
pass-through path. 
The second embodiment 38 of the volatile carrier of the invention has a 
columnar reservoir block 48 that is longitudinally extended. The second 
embodiment 38 includes a block container 50 secured to a first end 52 of 
the reservoir block 48, the block container capable of substantially 
containing the reservoir block. The block container 50 is attachable to 
the heater device 40, with a second end 54 of the columnar reservoir block 
48 aligned with and insertable into the passage 42. The reservoir block 48 
is longitudinally movable with respect to the block container 50 by a 
manually operable block advancer, so that the reservoir block can be 
manually advanced into the passage 42 and past the heat transfer site. 
Preferably the block container 50 includes a shell 56 that attaches at the 
entrance port 44. Preferably a block holder comparable to that shown at 58 
in FIG. 6 is attached to or at least is operably related to the first end 
52 of the reservoir block 48. Preferably the shell 56 and the entrance 
port 44 have threads and attach in threaded relation, although bayonet, 
snap, friction, or other attachment mechanisms well known to those skilled 
in the art may be used instead. The block advancer preferably forms a part 
of the block container 50. The block holder 58 can be designed to be 
slidably engaged with the shell 56 (by simply sliding within the shell or 
by some other conventional arrangement, not shown), with provision made 
(not shown) for a user to slide the block holder relative to the shell to 
move the reservoir block past the heat transfer site. 
However, preferably the block advancer includes a knob 60 that is 
longitudinally fixed but rotatably engaged to the shell 56 and that, when 
turned relative to the shell, moves the reservoir block 48 past the heat 
transfer site. A threaded shaft 62 extends parallel to the longitudinal 
axis of the reservoir block 48 and preferably is fixedly attached to the 
knob 60, thereby being attached to the shell 56 in longitudinally fixed, 
rotating relation. The threaded shaft 62 is threadedly engaged with the 
reservoir block 48, either directly or by way of threaded engagement with 
the block holder 58. The threaded portion of the reservoir block 48 or 
block holder 58 constitutes a nut attached to the reservoir block in both 
longitudinally and rotationally fixed relation. 
The reservoir block 48 (either directly or via the block holder 58) can be 
secured from rotating within the shell 56 by a longitudinally extending 
slot 64 in the reservoir block and/or the block holder engaging a 
longitudinally extending rib 66 on the shell, as is shown in FIGS. 6 and 
7. That and alternative arrangements to secure a structure such as the 
reservoir block 48 from turning within a structure such as the shell 56 
are well known to the art. Then, when the knob 60 and attached threaded 
shaft 62 are rotated, the reservoir block 48 will move longitudinally. 
Similarly, the reservoir block 48 can be moved by the knob 60 if the 
threaded shaft 62 is fixedly attached to the reservoir block (either 
directly or via the block holder 58) and is threadedly engaged in the 
knob. In this arrangement, the knob functions as a nut, turning in 
threaded relation on the threaded shaft. 
It is desirable that the block advancer provide a signal to a user that 
corresponds to movement of the reservoir block as it is advanced past the 
heat transfer site. Preferably the block advancer includes a detent 
mechanism that overcomeably resists turning movement of the knob 60 
relative to the shell 56 as the knob is turned in successive, incremental 
amounts. For example, interior surfaces of the knob 60 may have scallops 
68 that present toward the shell 56, and the shell may have a spring 70 
biased toward and slideably engaged in the scallops, as is best shown in 
FIG. 8. As the knob 60 is turned, the spring 70 snaps from scallop 68 to 
succeeding scallop to provide a tactile signal to a user of an incremental 
movement of the knob 60 and therefore of the reservoir block 48. 
A third embodiment of the volatile carrier of the invention is shown 
generally at 72 in FIG. 9. Parts and features of the third embodiment 72 
that directly correspond to those of the first and second embodiments 
10,38 will be given like reference numbers and will not be separately 
discussed. The third embodiment 72 is used generally in the same way as 
the second embodiment 38, just described, except that a knob 74 
(functionally corresponding to the knob 60 of the second embodiment 38) is 
internally mounted within a shell 76 (that functionally corresponds to the 
shell 56 of the second embodiment). A lug 78 projects from the knob 74 to 
releasably engage notches 80 formed in the shell 76 and thus provide a 
tactile and visual signal of incremental advance of a reservoir block 82 
(which corresponds to the reservoir block 48 of the second embodiment). 
The notches 80 may be marked with written indicia, such as the numbers 
shown in FIG. 9, to signal a user to advance the reservoir block 82, 
purely as a non-limiting example, perhaps once every evening to introduce 
a fresh portion of the reservoir block to the heat transfer site, 
releasing a nightly amount of an insect control ingredient. Various 
mechanisms for advancing the reservoir block 82 by turning the knob 74 43 
will be apparent to one skilled in the art and can generally correspond to 
the structures disclosed with respect to the second embodiment 38. 
Both the second and third embodiments 38,72 are provided with removable 
caps 71,84 that cover their respective reservoir blocks prior to use to 
avoid the premature loss of volatile active ingredient. 
The preceding description is merely of preferred embodiments of the 
invention. One skilled in the art will readily apprehend alternative 
embodiments that nevertheless fall within the scope and breadth of the 
invention. Thus, the claims should be looked to in order to understand the 
full scope of the invention. 
INDUSTRIAL APPLICABILITY 
The volatile carrier of the invention is useful for supplying volatile 
ingredients to appropriate dispensers, which ingredients are useful for 
controlling insects, scenting or deodorizing the air, and for other 
purposes.