U.S. patent application number 09/081637 was filed with the patent office on 2001-08-30 for paper towel dispenser.
Invention is credited to FORMON, JOHN S., MORRIS, ANDREW R., MURPHY, JAMES H..
Application Number | 20010017309 09/081637 |
Document ID | / |
Family ID | 22165399 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010017309 |
Kind Code |
A1 |
FORMON, JOHN S. ; et
al. |
August 30, 2001 |
PAPER TOWEL DISPENSER
Abstract
A powered dispenser for dispensing individual paper towel
segments from a continuous roll of paper provided with spaced lines
of tearing comprises a housing, a support for the roll of paper, a
feed mechanism, and a control device. The control device senses the
presence of a user to activate the feed mechanism, controls the
amount of material which is dispensed from the housing for any one
cycle, and prevents further dispensing of the paper until the
previous segment is separated from the roll. The control device
detects the leading edge of the paper to initiate monitoring of the
length of paper to be dispensed to prevent any cumulative error in
dispensing the segments.
Inventors: |
FORMON, JOHN S.; (ORANGE
PARK, FL) ; MORRIS, ANDREW R.; (GREEN COVE SPRINGS,
FL) ; MURPHY, JAMES H.; (ST. AUGUSTINE, FL) |
Correspondence
Address: |
BANNER & WITCOFF LTD
1001 G STREET NW
WASHINGTON
DC
200014597
|
Family ID: |
22165399 |
Appl. No.: |
09/081637 |
Filed: |
May 20, 1998 |
Current U.S.
Class: |
225/1 ;
225/10 |
Current CPC
Class: |
Y10T 225/205 20150401;
A47K 10/3625 20130101; Y10T 225/393 20150401; Y10T 225/12 20150401;
Y10T 225/21 20150401; Y10T 83/543 20150401; A47K 10/36 20130101;
A47K 10/3612 20130101; Y10T 225/246 20150401; Y10T 225/10 20150401;
A47K 2010/3668 20130101; Y10T 225/209 20150401 |
Class at
Publication: |
225/1 ;
225/10 |
International
Class: |
B65H 035/10 |
Claims
1. A dispenser for flexible sheet material comprising: a support
for rotatably supporting a roll of sheet material; a feed mechanism
for advancing the sheet material; a motor for driving the feed
mechanism; a control device for powering said motor to drive said
feed mechanism so as to dispense a predetermined length of the
sheet material; and a sensor for detecting a leading edge of said
sheet material and activating said control device.
2. The dispenser of claim 1, wherein said feed mechanism includes a
feed roller driven by said motor and an opposing pressure roller
between which the sheet material is passed.
3. The dispenser of claim 2, wherein said feed mechanism further
includes a drive gear and a rotatable axle to support said feed
roller and said drive gear, and said motor is provided a worm gear
engaged with said drive gear.
4. The dispenser of claim 2, wherein said control device includes
an encoder for determining the predetermined length of sheet
material.
5. The dispenser of claim 2 further comprising a housing with a
discharge opening, said support and said feed mechanism being
within said housing.
6. The dispenser of claim 5, wherein said sensor is positioned
between said feed roller and said discharge opening.
7. The dispenser of claim 1 further comprising a housing with a
discharge opening, said support and said feed mechanism being
within said housing.
8. The dispenser of claim 1, wherein said sensor is a
photo-detector device.
9. The dispenser of claim 1, wherein said control device includes a
counter device.
10. The dispenser of claim 1, wherein said control devices includes
a timer device.
11. The dispenser of claim 1, further comprising an activation
sensor for sensing the presence of a user and activating said
motor.
12. The dispenser of claim 11, further comprising means for
preventing activation of said motor when said sensor detects a
dispensed but unremoved segment of the sheet material.
13. The dispenser of claim 1, further comprising means for
preventing activation of said motor when said sensor detects a
dispensed but unremoved segment of the sheet material.
14. A dispenser for flexible sheet material comprising: a feed
mechanism for dispensing a first segment of the sheet material; a
sensor for sensing the presence of a user, said sensor activating
said feed mechanism for advancing the web of sheet material in
response to sensing the user; and a controller for preventing said
feed mechanism from dispensing a second segment of the sheet
material through said discharge opening until the first segment of
sheet material has been removed.
15. The dispenser of claim 14, wherein said controller includes a
sensor for sensing the presence of the first segment of the sheet
material when dispensed but not removed.
16. The dispenser of claim 14, wherein said activating sensor
includes a light sensitive sensor.
17. The dispenser of claim 14, wherein said feed mechanism includes
a motor.
18. The dispenser of claim 17, wherein said controller includes a
device for controlling the length of the first segment of the sheet
material, said control device terminating the actuation of said
motor when a predetermined length of sheet material has been
dispensed.
19. The dispenser of claim 12 further comprising a housing with a
discharge opening, said support and said feed mechanism being
within said housing.
20. The dispenser of claim 14, wherein said feed mechanism includes
at least one feed roller to dispense to the sheet material and a
motor to drive said feed roller.
21. A dispenser for dispensing sheets defined by perforations in a
roll of paper held thereby, said dispenser comprising: a motorized
feed mechanism with an output end from which a leading end of said
roll of paper is fed to make at least one of said sheets accessible
to allow said user to remove said at least one of said sheets from
a remainder of said roll; a controller connected to control said
feed mechanism and configured to feed said at least one of said
sheets responsively to an input generatable by said user; a sheet
detector connected to said controller and configured to indicate
whether a fed one of said at least one of said sheets is removed
from said remainder of said roll; said controller being further
configured to retract said at least one of said sheets after a
lapse of a predefined interval and responsively to said sheet
detector.
22. A dispenser as in claim 21, wherein said sheet detector is
positioned to detect a presence of said at least one of said sheets
adjacent said output end.
23. A dispenser as in claim 21, wherein: said dispenser has a
housing with an opening at said output end, said opening having a
blind end and an access, said access being sufficiently narrow to
prevent manual access by said user therethrough; said controller is
configured to feed one of said sheets for each of said inputs and
further configured to feed just enough of said roll, such that a
perforation line separating said one of said sheets is held, after
of feeding of said feed mechanism, between said access and said
blind end, whereby, when said one of said sheets is separated from
said remainder at said perforation line, a new leading end defined
as a result, is guarded against access by said user until a new
input by said user.
24. A dispenser for dispensing sheets defined by perforations in a
roll of paper held thereby, said dispenser comprising: a housing
with an opening, said opening having a blind end and an access,
said access being sufficiently narrow to prevent manual access by a
user therethrough; a motorized feed mechanism with an output end
from which a leading end of said roll of paper is fed to make at
least one of said sheets accessible to allow said user to tear said
at least one of said sheets from a remainder of said roll; a
controller connected to control said feed mechanism and configured
to feed said at least one of said sheets responsively to an input
generatable by said user; said controller being further configured
to stop said feed mechanism at a point at which said perforation
line is held between said access and said blind end, whereby, when
said one of said sheets is separated from said remainder at said
perforation line, a new leading end defined as a result, is guarded
against access by said user until a new input by said user.
25. A dispenser as in claim 24, wherein: said controller includes a
paper leading edge detector between said access and said blind end;
said controller including a displacement encoder connected to said
feed mechanism to detect successive increments of a feeding of said
paper by said feed mechanism; said leading edge detector being
positioned such that a detection of said leading edge after said
feed motor is started and a continued running of said feed motor
subsequent to said detection for a predefined number of said
increments is effective to position new leading edge at said
point.
26. A dispenser for dispensing sheets defined by perforations in a
roll of paper held thereby, said dispenser comprising: a motorized
feed mechanism with an output end from which a leading end of said
roll of paper is fed to make at least one of said sheets accessible
to allow said user to tear said at least one of said sheets from a
remainder of said roll; a controller connected to control said feed
mechanism and configured to feed said at least one of said sheets
responsively to an input generatable by said user; said controller
including a plurality of paper leading edge detectors; said
controller including a displacement encoder connected to said feed
mechanism to detect successive increments of a feeding of said
paper by said feed mechanism; said leading edge detectors being
positioned such that a detection of said leading edge by at least
one of said leading edge detectors after said feed motor is started
and a continued running of said feed motor subsequent to said
detection for a predefined number of said increments is effective
to position new leading edge at said point, whereby said leading
edge is detected even if said leading edge is not defined by a
contour of said perforation.
27. A method of dispensing a flexible sheet material having spaced
apart, transverse tearing lines from a dispenser, said method
comprising: activating a motor to advance a predetermined length of
the sheet material from a dispenser; sensing the leading edge of
the advancing sheet material to control the amount of sheet
material to be dispensed; and tearing a leading segment of the
sheet material along one of the tearing lines.
28. The method of claim 27, further comprising preventing the
advancing of additional sheet material until the advanced segment
of sheet material has been torn off.
29. The method of claim 27, wherein said motor is activated by
sensing the presence of a user.
30. A method of dispensing a flexible sheet material comprising
sensing the presence of a user, activating a motor to advance a
first segment of a sheet material from a dispenser when the
presence of a user is sensed, and preventing further advancement of
the sheet material until said first segment is removed from the
sheet material.
31. The method of claim 30, further comprising sensing of the first
segment when dispensed but not removed from the sheet material.
32. The method of claim 30, further comprising sensing a leading
edge of the advancing first segment and dispensing a predetermined
amount of sheet material from said sensing of the leading edge.
33. A method of controlling a powered towel dispenser that feeds
separate sheets defined by perforations in a roll of towel material
held by said dispenser, said method comprising the steps of:
detecting a request for a sheet of said towel; power-feeding said
towel material from said roll responsively to said step of
detecting; detecting a leading edge of said towel material and
triggering a counting of counting successive incremental feedings
of said towel material by an encoder responsively to second step of
detecting and terminating said power-feeding when said a count
resulting from said counting reaches a predefined value, said
predefined value being effective to dispense a single one of said
separate sheets.
34. A method as in claim 33, further comprising the steps of
pausing after said step of terminating and reversing said
power-feeding after a lapse of a predefined interval of time where
by said single one of said separate sheets is withdrawn into said
dispenser.
Description
TECHNICAL FIELD
[0001] The present invention generally relates to paper towel
dispensers and, more particularly, to a non-touch paper towel
dispenser for dispensing a web of material from a roll.
BACKGROUND OF THE INVENTION
[0002] Dispensers for toweling have primarily been designed to
dispense a continuous length of web material, folded paper towels,
or rolls of paper towels. Continuous towels are generally made of a
reusable material and form a towel loop outside of the dispenser
cabinet for the consumer to use. Folded towels are paper towels
which are pre-cut and folded into various configurations to be
individually dispensed for use. Roll towels are continuous rolls of
paper toweling which are wound around a central core and which are,
upon dispensing, separated into and delivered as individual lengths
of material.
[0003] Continuous web dispensers, such as those disclosed in U.S.
Pat. No. 2,930,663 to Weiss and U.S. Pat. No. 3,858,951 to
Rasmussen, require the user to pull on the loop of exposed toweling
in order to cause a length of clean toweling to be dispensed and
the exposed soiled toweling to be correspondingly taken up within
the dispenser. Although economical, the continuous exposure of the
soiled toweling is deemed unsightly and, therefore, unacceptable to
many consumers when compared to the many available alternatives.
Further, the exposure and possible reuse of soiled toweling may
present additional health hazards and sanitation concerns which
should be avoided.
[0004] The use of interfolded paper towels or C-fold paper towels
eliminates the potential health risks associated with continuous
web toweling. For instance, dispensers for folded paper towels,
such as disclosed in U.S. Pat. No. 3,269,592 to Slye et al., allow
a user to dispense the towels by pulling on the exposed end of each
new individual towel. These dispensers are also easy to refill with
folded towels. However, a number of the folded towels will
sometimes drop out of the lower opening of the dispenser when only
the exposed towel is pulled, especially when the stack of towels in
the dispenser is small. This can result in a significant waste of
paper towels. Accordingly, folded towels are not as economical as
other kinds of alternative dispensers.
[0005] Roll towels are cheaper to manufacture and produce less
waste than folded towels. Roll towels also eliminate the potential
health and sanitation problems associated with continuous web
toweling systems. Dispensers for roll towels may include a lever,
crank, or other user-activated mechanism for dispensing a length of
towel, and a blade for severing the length of towel from the
remaining roll. However, as can be appreciated, manual contact with
a dispensing lever or the like raises health concerns for the user.
To alleviate these health concerns, dispensers, such as U.S. Pat.
No. 4,712,461 to Rasmussen, eliminate contact with any part of the
dispenser, and instead rely upon the user directly pulling the
paper towel out of the dispenser. As a result, the paper towel must
be provided with sufficient strength to effect rotation of the feed
roller and actuation of the blade without premature tearing. Paper
possessing the requisite strength to operate the dispenser is
limited in the amount of softness and absorbency which can be
provided to the paper towels.
[0006] Dispensers for roll towels have also been electrically
powered. As shown in U.S. Pat. No. 5,452,832 to Niada, a light
sensitive device is used to detect the presence of a user's hand in
front of the dispenser and advance the toweling for a predetermined
length of time. The dispensed length of paper towel is then
separated from the continuous web by pulling the paper against a
serrated cutting member. While the feed roller is powered, the
cutting action still requires the paper to possess a certain
minimum strength and generally produces a rough, unsightly cut.
[0007] U.S. Pat. No. 4,738,176 to Cassia discloses an electrically
powered dispenser which also includes a reciprocating cutter to
produce an individual towel from the continuous web of paper. While
this arrangement enables the use of softer and more absorbent
paper, the dispenser requires a substantial amount of energy to
drive the feed mechanism and the reciprocating cutter. Accordingly,
the batteries must be replaced much more frequently. Moreover, the
system is more complex and costly with its use of one-way
clutches.
[0008] Also, in some electrically powered dispensers, such as U.S.
Pat. No. 4,796,825 to Hawkins, the paper will continually dispense
while a hand or other object is placed in front of the sensor.
Hence, the dispenser is subject to easy abuse and waste of paper.
Moreover, some dispensers are subject to dispensing paper by the
general proximity of a person irrespective of whether a paper towel
is needed. In an effort to avoid abuses, some dispensers, such as
U.S. Pat. No. 4,666,099 to Hoffman, have incorporated a waiting
period where the dispenser will not operate for a brief time after
each use. However, the need to wait can be frustrating to users
under some circumstances.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to an electrically powered
dispenser which overcomes the disadvantages of the prior art.
[0010] In one aspect of the present invention, the dispenser
facilitates the dispensing of a roll of paper with spaced apart
transverse lines of tearing (e.g. perforation lines) for easily
separating individual sheets from the continuous roll without
cutting. As a result, paper with a high degree of softness and
absorbency can be used without the high energy demands required by
a reciprocating cutter.
[0011] In another aspect of the invention, the dispenser senses the
leading edge of the continuous web of paper material to initiate a
control device which controls the length of each segment of paper.
In this way, the dispenser can always place the transverse tearing
line at the proper position in relation to the discharge opening
for each dispensed sheet, irrespective of variations of the spacing
for the tearing lines within a tolerance range.
[0012] In another aspect of the invention, the dispenser includes a
sensor for sensing the presence of a sheet which has been
dispensed, but not removed, in order to prevent the dispenser from
dispensing any more sheets until the previous sheet has been torn
off. In this way, abuse of the dispenser and waste of the paper
material can be minimized without requiring the use of a waiting
period wherein the dispenser will not operate. Accordingly, the
dispenser is always ready for use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a side diagrammatic view of the dispenser of the
present invention with the cover in a closed position and showing a
sheet segment of a web being dispensed.
[0014] FIGS. 2 and 3 are flow diagrams showing flow control for
operating a dispenser according to embodiments of the
invention;
[0015] FIG. 3a is a portion of a routine for dealing with alarm
conditions in the control flow shown in FIG. 3.
[0016] FIGS. 4 is a block diagram showing control elements for
controlling a towel feeder according to embodiments of the
invention.
[0017] FIGS. 5 and 6 are flow diagrams showing alternative jam
clearing methods consistent otherwise with the control flow of
FIGS. 3 and 3a.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0018] Referring to FIGS. 1 and 4, a non-touch paper towel
dispenser 10 according to the present invention comprises a chassis
12 which includes a back panel 14, side panels 16, and a pivotal
front cover 20 attached by a pin, hinge, or other conventional
attachment mechanism 20a (FIG. 1). Front cover 20 is opened to
permit loading of a roll of paper material 25 into dispenser 10.
The roll 25 consists of a continuous web of paper 27 wound upon a
hollow, cylindrical core (not shown). In the preferred embodiment,
the web 27 includes a series of spaced apart, transverse tear lines
to subdivide the web into sheet segments 42 of a predetermined
length. Roll 25 is rotatably supported a pair of arms 35 extending
forwardly from back panel 14. Each of the arms includes inwardly
directed hub 35' loosely received within the core 38' of the roll
25 to permit free rotation of the roll 25. Nevertheless, other
mounting arrangements could be used.
[0019] A feed mechanism 37 is mounted within the housing defined by
chassis 12 to dispense the web 27 in incremental sheet segments 42.
In the preferred construction, feed mechanism 37 includes a feed
roller 22 and a pressure roller 24. Feed roller 22 and pressure
roller 24 are mounted upon axles 45, 46, respectively, rotatably
supported by side panels 16, 18. The pressure roller 24 is
preferably biased against the feed roller by a spring (not shown)
to define a feed nip 47 for dispensing the web 27 through a
discharge opening 48. The discharge opening includes a towel sensor
38 as described below.
[0020] In use, feed roller 22 is driven by an electric motor 30
mounted within the dispenser. Specifically, a worm gear 52 is
secured to drive shaft 54 of motor 30 to engage a drive gear 56
secured to axle 45 and rotate feed roller 22. When the paper web 27
is fed into nip 47, rotation of the feed roller (counter clockwise
as viewed in FIG. 1) causes the web to be advanced around feed
roller 22, through discharge opening 48. A guide plate 87 is
provided to direct the web along the desired path. Low power
requirements insure that the batteries 58 need only infrequent
replacement. Other feed mechanisms having other roller and gear
arrangements, or other power supplies, such as a step down AC to
D.C. power supply, could be used.
[0021] When a roll 25 is loaded into dispenser 10, the leading edge
36 of web 27 is manually fed rearward between feed roller 22 and
pressure roller 24. When front cover 20 is closed, a loading switch
(not shown) may be engaged to activate motor 30 and automatically
drive feed roller 22 in a direction (i.e. counter-clockwise as
viewed in FIG. 1) to advance web 27 around feed roller 22 and to
discharge opening 48. Alternatively, as described in the control
embodiment of FIG. 2, a custodian can set up the roll 25 and web 27
such that the leading edge 36 is downstream of the sheet sensor 38.
When cover closure is detected, the motor 30 will run in reverse to
bring the leading edge 36 upstream of the sheet sensor 38 and then
stopped (See discussion of FIG. 2, below, for further explanation).
The custodian can use a forward and reverse jog switch 92 to
position the leading edge where desired. While the loading switch
is preferably actuated automatically upon closing of the cover, it
could be manually actuated if desired. The leading edge 36 of the
web material is advanced until detected by towel sensor 38
positioned in discharge opening 48. The towel sensor 38 is coupled
with a microprocessor 53 or the like so that once the leading edge
has been detected by sensor 38, motor 30 is reversed until the
leading edge 36 of web 27 is clear of the range of sensor 38. This
position places the leading edge 36 between the feed roller 22 and
sensor 38. The towel sensor 38 may be any suitable mechanism, for
example, a limit switch (not shown), an acoustical sensor (not
shown), or an optical sensor 38 that includes an emitter and a
photo diode that is occulted by the leading edge 36 of the web. In
the latter example, the emitter may be pulsed and the output of the
photodiode high-pass filtered. In this way the effect of ambient
light on the photodiode is compensated. This may be implemented
directly through microprocessor 53.
[0022] The present invention is preferably used for dispensing web
material with spaced apart tearing lines, such as prescored lines
of perforation, resulting in sheet segments 42 of, for example,
nine inches in length. Of course other lengths could be used
depending on designer preference. By using a preperforated web
material, the sheet segments can be easily separated from the web
without requiring cutting of the web. The perforation tensile
strength is light enough such that the web material can be easily
separated in a smooth edge or some other desired or appealing edge.
By avoiding the need for a cutter, energy may be conserved because
the motor needs only to rotate the feed roller. Because the web 27
is power fed, minimum strength is required of the web. The web does
not need to have sufficient strength to draw out additional
portions as a leading portion is removed as in dispensers that
require the web to be pulled out manually. Thus, the paper material
of which the web is made can be soft and highly absorbent.
[0023] Dispenser 10 further includes a proximity sensor 40 that
detects the presence of a user's hands or the like as the hand or
hands approach the front of the dispenser 10. Sensor 40 may be any
kind of suitable proximity sensor or switch. For hands free
operation, sensor 40 may be a proximity sensor. A Proximity sensor
40 is coupled with microprocessor 53 to activate motor 30 when a
hand is detected so as to drive feed roller 22 and thereby dispense
a predetermined length of the web material. The dispensed web exits
through discharge opening 48, in order to be easily accessible to
the user. The user then grasps the dispensed sheet segment 42 of
web material and tears off the desired length of material along a
prescored perforation line 72 (see FIG. 1). The leading edge 36 of
the next sheet segment 42a is positioned between towel sensor 38
and feed roller 22. If the user dispenses, but does not separate it
from the web, the towel sensor 38 detects the presence of the
segment 42a. As long as sheet segment 29a is detected by sensor 38,
the microprocessor will prevent further activation of motor 30.
This discourages abuse of the dispenser and waste of the paper.
Also, while the towel sensor 38 is described as a single, centrally
positioned sensor in discharge opening 48, a pair of spaced towel
sensors (not shown) could also be provided. In this case, even if
the leading towel segment is irregularly torn, apart from the
tearing line, only one towel sensor need be uncovered to enable
activation of the motor.
[0024] As explained further below, dispenser 10 feeds a single
sheet segment 42 of web 27 after detecting that a previously fed
sheet segment has been separated from the web 27. To control the
amount of web 27 fed so that one sheet segment only is fed,
dispenser 10 employs a length detector 48 which establishes the
amount of web fed during each dispensing cycle each time the motor
is activated. The length detector 48 may be, for example, an
encoder, either electromechanical or optical, that outputs a pulse
for each increment of web dispensed. The length detector 48 may be
coupled to microprocessor 53 and employed in controlling the
dispenser 10 as discussed below. Another alternative to encoding
successive incremental displacements of the web 27 is to detect the
difference in transmissivity of the web when a perforation line
crosses an optical interrupter. That is, an emitter-photodiode
combination may be used to provide a signal that indicates a first
level of light reception as web is fed and when the perforation
crosses the light path. A pulse may be generated by the presence of
the perforations through the web. The microprocessor 53 may count
the pulses generated by the length detector 48 where an encoder
embodiment is employed to dispense the proper amount of web
material. For instance, when the tearing lines are nine inches
apart, the microprocessor counts the corresponding number of pulses
to dispense nine inches of the web 27. While a dispenser is
preferably set to dispense a roll with sheet segments (or a
multiple of sheet segments) of a predetermined length, a switch,
dial, button or other means could be used to adjust the length of
the dispensing cycle to meet different kinds of rolls. Also, other
control devices could be used, including other counting
arrangements or a timer device. Note that in the encoder
embodiments of length detector 48, as discussed below, cumulative
error does not occur because cumulation of incremental lengths does
not begin until the leading edge 36 is detected. Thus error can
only accumulate over the span of a single sheet segment 42.
[0025] If a user pulls on the leading edge of the sheet segment
being dispensed before the cycle has been completed, the motor 30
may stall due to the increased load placed on the worm gear 52. The
web 27 may be prevented from slipping about feed roller 22 when
pulled because of the braking characteristic of the worm gear and
the pinching engagement of the feed nip 47. When the motor stalls,
the microprocessor 53 may store the cumulative displacement and
reactivate the motor to dispense the remaining portion of the sheet
segment after a short pause (See FIG. 6 and attending discussion,
below). Alternatively, the motor may be reversed so that the sheet
segment is pulled upstream of the towel sensor 38 and fed forward
again to register the portion of the leading edge again in
preparation for a new dispensing cycle.
[0026] Referring to FIG. 2, control flow for embodiments of towel
dispenser 10 may begin with the detection of an open cover or towel
request at step S100. If a sheet request is made, control proceeds
to step S105 where it is determined if a towel is present, that is,
if a previously fed towel has not been torn off. If a towel is
present, control returns to step S100 otherwise it proceeds to step
S120 where the feed motor 30 is started in the forward feed
direction. The feed motor 30 continues until in step S130, the
leading edge of the towel is detected at which point, the length
(displacement) detector 48 is initialized in step S140 so that the
total displacement of the web 27 can be detected. The web 27 is
advanced for the predefined displacement to expose one full towel
sheet segment 42 in step S150 as indicated by the length detector
48. Next, in step S160, an exposure timer is initialized. Next, at
step S170 optical sensor 38 is polled to determine if a towel has
been removed within the duration of the exposure timer. If not,
control loops until the exposure timer times out at step S180. If
the towel is removed before the exposure timer times out, control
returns to step S100. If the exposure timer times out in step S180,
control proceeds to step S190 where the feed motor 30 is reversed
to draw the towel back inside the dispenser 10. In step S190, the
reverse feed continues for a short first interval to draw the
leading edge back past the towel sensor 38. If the towel edge was
not detected due to some error in step S195, an alarm is set at
step S10 and control proceeds to step S10. If the towel edge 36 is
successfully detected (Step S190 may include a timer operation so
that the program may wait for a predetermined period of time before
proceeding to step S195), control returns to step S100. If a
cover-open condition is detected in step S100, control also
proceeds to step S10. The program pauses at step S30 until a cover
closure is detected at step S30, whereupon control proceeds to step
S90. In step S90, the feed motor 30 is reversed in an operation as
in step S190. Then control returns to step S100 where the dispenser
10 waits for another sheet request.
[0027] Referring to FIG. 3, an alternative control flow begins when
the dispenser is reset (either power on or pressing a reset button
91') whereupon control begins at step S205. In step S205, the
processor 53 waits for a sheet request. As discussed above, this
request may be made by a proximity sensor in one embodiment, or by
some other type of switch or indicator. When a sheet request is
made, control passes to step S210 where the sheet detector 38 is
polled to determine if a sheet segment is still present having been
ejected previously and not torn off. At step S220, if a sheet is
detected, control returns to step S205. If the sheet is not
detected, the feeder motor is started in step S225 and a watchdog
timer initiated. Then in step S235, the sheet detector is polled
and at step S240 if the sheet is detected, control proceeds to step
S245. If the sheet is not detected, control loops back through
steps S230 to S235 until the watchdog timer times out in step S230
whereupon control branches to step S250 in which an alarm is set
and the motor stopped to wait for reset.
[0028] Note that in step S235, the presence of the sheet is an
indication of the leading edge of the web. Therefore, in step S245,
the encoder pulse detector of the encoder embodiment (length
detector 48) is zeroed and control flows to step S280. In step
S280, another watchdog timer is started and the processor waits for
each encoder pulses by looping through steps S285 and S260. If the
watchdog timer times out between pulses, control branches out of
this loop to step S255. Each time a pulse is detected, control
flows to step S290 where the pulse counter is checked against the
cumulative count of pulses thus far. If the cumulative count is
short of the number corresponding to a full sheet, control returns
to step S280. If all the pulses are cumulated through the S280,
S285, S290 loop, control proceeds to step S295 where the motor is
stopped. Control then returns to step S205.
[0029] If the watchdog timer in step S260 times out, control
proceeds to step S255 where the feed motor 30 is reversed and
another watchdog timer is initiated. The sheet detector is polled
and control loops through steps S265 and S275 until either the
watchdog timer times out or the edge is detected. If the edge is
detected the feed motor continues in reverse for a short interval
to bring the sheet edge upstream of the optical sensor (sheet
detector) in step S270. Then control proceeds to step S225. If the
watchdog timer times out in step S275, control proceeds to step
S250.
[0030] Note that in either of the above control embodiments or any
others (FIGS. 2 or 3), a routine may be included to insure
prevention of more than a predefined number of sheets from being
dispensed within a specified time interval. If more than this
predefined number of requests is made, the controller may be
programmed to ignore the request until the lapse of a timer. So,
for example, if more than three requests are made in a 10 second
period, the processor can wait until the expiration of the ten
second interval or for the expiration of a new 10 second interval
after the third request. This is an abuse deterrent.
[0031] Note that discharge opening 48 defines an access that is
narrow enough to prevent a user's fingers from reaching the leading
edge 36 of the web 27 when the dispenser 10 is waiting for a
request for a new paper sheet segment. The towel sensor 38 is
located between the access defined by the discharge opening 48 and
the blind end defined by a feedthrough between feed roller 22 and
an arcuate guide plate 87. With this arrangement, the towel sensor
is hidden from interference by ambient light. Also, the perforation
line 72 is located downstream of the blind end so that a sheet
segment 42 can be torn away from the web 27. The perforation line
72 is above the towel sensor 38 when the dispenser 10 is waiting
for a request. In this way the towel sensor 38 registers the
position of the leading edge 36 shortly after the motor 30 starts
feeding forward.
[0032] The control flow starting with step S255 is for the purpose
clearing a jam. Referring to FIG. 5, an alternative way of dealing
with the timeout in step S260 of the watchdog timer begins at step
S355 where the feed motor 30 is reversed. Control loops through
step S365, until the encoder pulses are cumulated for a short
number of counts, perhaps only one or two. Thus, the feed motor is
reversed for only a short interval of reverse displacement. The
count of the forward feed operation is then adjusted in step S370
and the feed-forward operation resumed at step S280. Thus, if two
backward pulses are used for this correction, the cumulative count
employed in step S290 would be decremented by two to make up the
difference.
[0033] Another alternative way to deal with a jam is to simply
pause the forward feed operation. Referring to FIG. 6, in step
S455, the feed motor 30 is stopped and a delay timer initiated.
Control loops through step S465 until the delay timer times out and
the feed motor is restarted in step S470. After that control
returns to step S280.
[0034] Referring to FIG. 4, a block diagram showing the various
sensors and controls that may be connected to microprocessor 53,
according to the various embodiments discussed above, is shown.
[0035] It will be obvious to one of ordinary skill in the art that
numerous modifications may be made without departing from the true
spirit and scope of the present invention, which is to be limited
only by the appended claims.
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