Abstrict As each tube is fed into the feed chute of a fluorescent lamp tube
crusher, and regardless of the size of the tube, a sensor switch
in the chute immediately sends a count signal to an associated tube
counter, and also produces an inhibit signal which prevents a second
count signal from being applied to the counter for a predetermined
interval of time that is greater than the time it takes to grind
up a tube of a first size and that is less than the time it takes
to crush a tube of larger size. If at the end of the interval a
tube of larger size is still being crushed, a second count signal
is applied to the counter.
Claims I claim:
1. In a fluorescent lamp crusher of the type having a feed chute
for guiding fluorescent lamp tubes of different sizes intermittently
and one-by-one to a crusher mechanism to be crushed thereby, improved
control apparatus, comprising
first signal generating means operative to produce a first signal
of a first duration each time a tube of a first size is guided by
said chute to said crusher mechanism, and operative to produce a
second signal of a second duration longer than said first duration
each time a tube of a second size larger than said first size is
guided by said chute to said crusher mechanism, and
second signal generating means operative upon each production of
either of said first and second signals initially to produce a third
signal of a third duration shorter than said first duration,
said second signal generating means including inhibiting means
operative for the duration of one of said first signals, and for
a predetermined interval of time thereafter, to inhibit production
of a second one of said third signals, whereby each of said first
signals produces only one of said third signals.
2. A fluorescent lamp crusher as defined in claim 1 wherein said
second signal generating means further includes means operative,
prior to the expiration of one of said second signals, and after
said predetermined interval of time, to produce a second one of
said third signals.
3. A fluorescent lamp crusher as defined in claim 2 including
a counter having a signal input and a signal output, and adapted
to produce a signal on said output after having a predetermined
number of count signals applied to said input, and
means for applying each of said third signals as a count signal
to said counter input, whereby said counter input receives one count
signal for each tube of said first size that is guided to said crusher
mechanism, and two count signals for each tube of said larger size.
4. A fluorescent lamp crusher as defined in claim 1 wherein
said inhibiting means comprises a fourth signal produced concurrently
with said initially produced third signal, and having a duration
greater than said first duration and less than said second duration,
and
said fourth signal being operative upon termination thereof prior
to the termination of one of said second signals to produce a second
one of said third signals.
5. A fluorescent lamp crusher as defined in claim 1 wherein said
second signal generating means comprises
a pair of timers each having s signal input and a signal output,
means connecting the inputs of said timers to said first signal
generating means simultaneously to receive signals therefrom,
one of said timers being operative to produce one of said third
signals on its output each time one of said first signals is applied
to its input, and
means operative to produce two of said third signals on the output
of said one timer each time one of said second signals is applied
to its input.
6. A fluorescent lamp crusher as defined in claim 5 wherein
the other of said pair of timers is operative, each time one of
said first and second signals is applied to its input, to produce
on its output s fourth signal of a duration longer than said first
duration and shorter than said second duration, and
said inhibiting means includes means interposed between said first
signal generating means and the input to said one timer, and operative
for the duration of one of said fourth signals to prevent more than
one signal from being applied to the input of said one timer.
7. A fluorescent lamp crusher as defined in claim 6 including
means operative upon expiration of said fourth signal, during the
presence of one of said second signals, to apply a second input
signal to said first timer.
8. In a fluorescent lamp crusher having a chute for use in feeding
fluorescent lamp tubes of different sizes one-by-one to a crusher
mechanism, and a counter for interrupting the operation of the crusher
mechanism after a predetermined quantity of count signals have been
applied to an input of the counter, improved control apparatus for
operating said counter, comprising
switch means operative to produce a first signal upon each insertion
into said chute of a tube of a first predetermined size, and operative
to produce a second signal of longer duration than said first signal,
upon each insertion into said chute of a tube of a second size larger
than said first size, and
control means interposed between said switch means and said counter
and responsive to the initial production of each of said first and
second signals to apply one count signal to an input of said counter,
said control means including inhibit means operative after application
of said one count signal to said counter input to inhibit the application
of a second count signal to said counter input for a predetermined
interval of time greater than the duration of said first signal
and less than the duration of said second signal.
9. A fluorescent lamp crusher as defined in claim 8 including
means operative upon the initial production of one of said second
signals, and the subsequent expiration of said predetermined interval
of time, to apply a second count signal to the input of said counter.
10. A fluorescent lamp crusher as defined in claim 8 including
a second counter for actuating a warning device after a predetermined
quantity of said tubes have been crushed by said crusher mechanism,
and
means for applying said count signals simultaneously to the input
of the first-named counter, and to an input of said second counter.
11. A fluorescent lamp crusher as defined in claim 8 wherein said
control means comprises
a pair of timers, each having a trigger terminal connected to said
switch means, and an output terminal disposed to produce an output
signal thereon upon application of a trigger signal to its associated
trigger terminal,
said switch means being operative upon initial production of each
of said first and second signals momentarily to apply a trigger
signal to the trigger terminal of each of said timers whereby each
of said timers produces an output signal of predetermined duration
at its output terminal,
means connecting the output signal of one of said timers to the
input of said counter, thereby to apply a count signal to the input
of said counter each time a signal appears at the output terminal
of said one timer, and
said inhibit means includes means connecting the output signal
of the other of said timers to said trigger terminal of said one
timer, and operative to inhibit the application of another trigger
signal to the trigger terminal of said one timer for the duration
of the output signal from said other timer.
12. A fluorescent lamp crusher as defined in claim 11 wherein
the duration of the output signal of said other timer is greater
than the duration of the output signal of said one timer.
13. A fluorescent lamp crusher as defined in claim 11 wherein
the duration of the output signal of said other timer is equal to
said predetermined interval of time.
14. A fluorescent lamp crusher as defined in claim 11 wherein the
duration of the output signal of said one timer is less than the
duration of said first signal.
Description BACKGROUND OF THE INVENTION
This invention relates to fluorescent lamp crushers, and more particularly
to crushers of the type that are designed to crush fluorescent lamp
tubes of various lengths and shapes. Even more particularly this
invention relates to improved control apparatus for automatically
sensing the overall length of each tube inserted into the crusher,
and for simultaneously counting incremental lengths of the tubes
inserted into the crusher.
Fluorescent tubes or lamps of the type described frequently are
marketed in two different shapes--namely, straight or linear, and
curved or U-shaped in configuration. Moreover, such tubes normally
are marketed in three different lengths--namely, four feet long
or eight feet long for the linear or straight tubes, and two feet
overall for the U-shaped tubes. The straight tubes which are eight
feet in length contain twice as much glass and mercury vapor as
each of the straight four foot tubes and U-shaped tubes. Typically
tubes of the type described are crushed in fluorescent apparatus
of the type disclosed in the U.S. Pat. No. 4655404 wherein any
toxic mercury vapors, which are released upon the crushing of such
tubes, are drawn into and absorbed by a special filter that which
is associated with such apparatus.
However, it has been found necessary periodically to change the
filter element in crushers of the type noted above, because after
prolonged use the filter element becomes saturated and thereafter
fails to function properly. For that reason, as noted in the U.S.
Pat. No. 5205497 it has been customary to employ in connection
with such crushers a safety device which prevents further operation
of the crusher after a predetermined successive number of lamps
have been crushed. In that prior art control apparatus the feed
tube, which guides the fluorescent lamp tubes into the crusher,
contains a normally-open switch that is closed each time a new tube
is inserted into the crusher. The intermittently operated switch
operates a counter, which after a predetermined number of counts
have been made, interrupts the operation of the crusher until the
filter element is replaced. However, this mechanism result in to
inaccurate counting, because of the breaking of some fluorescent
tubes upon movement of the tubes into the machine feed chute. The
effect of such breaking is to create multiple operation of the normally-open
switch employed to count the number of tubes inserted into the machine,
and therefore frequently has led to an excessive count, and premature
replacement of the filter element.
To obviate the foregoing problem, crusher machines have been equipped
heretofore with a manually-operated tube size selector switch, which
the machine operator actuated at the time the tube was inserted
into the crusher machine to indicate whether the tube was a four
foot tube, an eight foot tube or a U-shaped tube. If the operator
properly operated the tube size selector switch, the mechanism produced
an accurate account representing the volume of the crushed tubes,
and consequently an accurate representation of the crushed glass
and mercury vapor released per tube. However, the accuracy depended
upon the conscientious operation of the tube size selector switch,
and if the machine operator failed properly to operate the selector,
then the count was inaccurate. Moreover, this created the possiblity
that the operator could deliberately fail to make the correct tube
size selection for the purpose of prolonging the useful life of
the associated filter element, in which case the element very often
could be operated after reaching its saturation point.
It is an object of this invention, therefore, to provide an improved
control apparatus for crushers of the type described, which will
provide a far more accurate measure of the crushed glass and vapor
created by the crusher subsequent to the insertion of the filter
element therein, and which will prevent any deliberate operation
of the crusher after its associated filter element has become saturated.
A more specific object of this invention is to provide improved
crusher apparatus of the type described which, in effect, automatically
and accurately senses the type of fluorescent tube which is inserted
into the machine, and which, regardless of the size and shape of
the tube inserted, provides an accurate count for each predetermined
quantity of crushed glass and mercury vapor released into the crusher.
Still another object of this invention is to provide for fluorescent
lamp crushers of the type described improved control apparatus which
includes means for automatically sensing the insertion of long and
short tubes into the crusher, including U-shaped tubes, and which
prevents any multiple or accidental triggering thereof.
Other objects of the invention will be apparent hereinafter from
the specification and from the recital of the appended claims, particularly
when read in conjunction with the accompanying drawing.
SUMMARY OF THE INVENTION
Study of the operation of the associated tube sensing switch during
repeated crushings of four foot, eight foot and U-shaped tubes in
apparatus of the type disclosed in the above-noted U.S. Pat. No.
5205497 (hereinafter the '497 patent) established empirically
that each of the three different types of tube produced a different
ON/OFF signature or pattern of the sensor switch. For example, for
each type of tube, it took an empirically predetermined interval
of time between the initial closing of the switch upon insertion
of a tube into the feed chute of the mechanism, and the final opening
of the switch after all portions of a given tube had been crushed.
Although the switch may have intermittently opened and closed during
such interval because of outside interference or noise, a signature
interval for each of the three different types of tubes was established.
To provide an accurate count (one count for each four foot length
of tube crushed) a timer controlled circuit was devised based upon
the three signatures noted above. Two of the signature intervals
(for four foot and U-shaped tubes) were similar, while the interval
for the eight foot tube was approximately double that of the four
foot and U-shaped tubes. Consequently the timer controlled circuit
utilizes one timer for producing one counter signal for each four
foot or U-shaped tube, and two successive counter signals for each
eight foot tube. A second timer functions to inhibit the production
of a second successive counter signal unless the sensor switch remains
closed continuously for an interval of time that falls between the
four foot and U-shaped tube interval, and the eight foot interval.
THE DRAWINGS
FIG. 1 is a perspective view illustrating in elevation a lamp crusher
mechanism having incorporated therein improved control apparatus
of the type made according to one embodiment of this invention,
a removable tube guide for the crusher mechanism being shown fragmentarily
and in phantom by broken lines;
FIG. 2 is a perspective view of a U-shaped flourescent lamp of
the type which is adapted to be crushed in a mechanism of the type
shown in FIG. 1;
FIG. 3 illustrates graphically the ON/OFF intervals or signatures
of the sensing switch of the herein described control apparatus
upon insertion into the crusher mechanism of, respectively, a four
foot tube, an eight foot tube and a U-shaped tube;
FIG. 4 is a graphic illustration of the two different signal outputs
which are generated by the dual timer which forms part of the control
apparatus described herein; and
FIG. 5 is a wiring diagram illustrating the overall control apparatus
employed for sensing and generating timer output or counter signals
for four foot tubes, eight foot tubes and U-shaped tubes as the
later are inserted into the crusher mechanism.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings by numerals of reference, and first
to FIGS. 1 and 2 10 denotes generally a crusher mechanism which,
for the most part, is generally similar to the crusher mechanism
disclosed in the above-noted '497 patent. In this connection, a
waste receptacle or drum 11 which is mounted on a wheeled carriage
12 has thereon a circular cover plate 14 secured by elastic cords
15 to the carriage 12. Numeral 16 denotes part of the plastic sleeve
which is interposed between the drum 11 and the crusher housing
(not illustrated), which is supported from the underside of cover
14. A control box 17 is mounted on the upper surface of cover 14
adjacent the filter housing 18 which is adapted to contain a removable
filter element of the type referred to in my '497 patent. At its
upper end the filter in housing 18 communicates with the outlet
end of an exhaust pipe 19 the opposite end of which is connected
to a fluorescent lamp feeder chute or guide 21.
Chute 21 which is different in configuration from the chute shown
in the '497 patent, has a generally rectangular, cross sectional
configuration. Its lower end communicates through an opening in
cover 14 with the crusher mechanism (not illustrated); and its upper
end normally is closed by a hinged brush element 25. Chute 21 is
adapted to have inserted into its upper end through the strands
of the brush element 25 U-shaped fluorescent tubes of the type denoted
by the letter L in FIG. 2. At the open end of tube L its two, spaced
leg sections are secured in spaced, parallel relation to each other
by a metallic stiffener S, which prevents any undesirable bending
of one leg section of the tube relative to the other. It is customary
to insert the tube L through element 25 in such manner that the
closed, curved lower end of the tube L is inserted first into the
chute 21 and the stiffener S is therefore the last portion of the
tube to enter the chute.
Shown in phantom and in broken lines in FIG. 1 is a cylindrically
shaped feed tube adapter 23 which, after element 25 has been swung
into its broken line position in FIG. 1 is removably insertable
into the upper end of the chute 21 whenever it is desired to insert
into the crusher mechanism linear or straight fluorescent tube sections,
such as for example conventional four foot tubes or eight foot tubes.
When the U-shaped tubes L are to be inserted into the chute 21 the
tubular adapter 23 of course, is removed from the upper end of
chute 21 and element 25 is swung back to its operative position
(full lines in FIG. 1). The guide 23 forms no part of this invention,
and therefore will not be described in greater detail herein. However,
it is to be understood that the apparatus as illustrated in FIG.
1 is adapted to accommodate and to crush any one of at least three
different types of tubes--namely, four foot, eight foot, or U-shaped
tubes. Moreover, each such tube upon being inserted into the guide
21 will encounter and be sensed by a sensor switch 24 which is
mounted on chute 21 intermediate the ends thereof. Sensor switch
24 as noted in greater detail hereinafter, is designed to be turned
ON when it senses the presence of a fluorescent tube in the chute
21 and is designed to be in an OFF mode, when no such tube is present
in chute 21.
As noted above, heretofore the sensing switch 24 whether mechanically
operated, optically operated or ultrasonically operated--suffered
from the same shortcoming, in that multiple or false operations
of the switch tended to take place during a tube crushing operation.
Consequently, therefore, it heretofore has been extremely difficult
to provide an accurate count of the tubes that have been crushed
over a given period of time. The importance of such count, as noted
in the '497 patent, is that each filter element should be replaced
after it has been exposed to a predetermined number of crushed fluorescent
lamps. Therefore, it has become necessary to compensate for, or
to avoid the introduction of false count signals, which are introduced
by switch noise (random opening and closing of the sensing switch)
during a crushing operation.
To effect this compensation, and over spaced intervals of time,
each of a plurality of four foot, eight foot and U-shaped tubes
were crushed in apparatus of the type shown in FIG. 1. The graphs
A, B and C of FIG. 3 represent, respectively, the ON/OFF (closed/open)
characteristics of the sensing switch 24 during the crushing of
four foot, eight foot and U-shaped tubes, respectively. Graph A
indicates that when four foot tubes are crushed, switch 24 is, generally
speaking, consistently ON for anywhere from 100 to 300 milliseconds
(ms). In the case of eight foot lamps (graph B), switch 24 is essentially
ON for anywhere from 600 to 1000 ms. On the other hand, in the
case of U-shaped lamps, the switch 24 is on, initially, for approximately
40 to 50 ms, during the time that the closed end of the U-shaped
lamp passes switch 24 after which switch 24 remains OFF for approximately
180 to 300 ms, except when the switch is momentarily ON (8 to 20
ms) as the stiffener S passes the switch 24. In addition to the
noise generated, as shown in graph A, at the beginning and at the
end of a crushing cycle for a four foot lamp, there might also be
intermittent, brief opening and closing of the switch during the
100 to 300 ms interval, but the true signature for a 4 foot lamp
is as illustrated in graph A. Likewise, although in addition to
the brief noise shown at the beginning of the graphs B and C, these
graphs reflect the true signatures of the switch 24 during the crushing
of eight foot and U-shaped lamps, respectively.
Given the tube signatures as shown in FIG. 3 it was then possible
to devise a circuit for counteracting or preventing undesirable
operation of swtich 24. For example, referring to FIG. 4 any sensing
of switch 24 in its ON mode, after a quiescent period, at T.sub.0
causes a first timer of the type noted hereinafter to issue or create
a 75 ms pulse to a counter, such as for example a counter noted
in the above-noted '497 patent. At the same time, a 500 ms inhibiting
pulse, which makes the first timer insensitive to any action of
switch 24 is generated by a second timer of the type noted hereinafter.
Then, if at the end of the 500 ms inhibition period, the sensing
switch 24 is still closed, or in its ON mode, then another 75 ms
output pulse is generated by the first timer in response to the
termination of the second timer, thereby once again to produce a
counter advancing signal.
More specifically, FIG. 5 illustrates a dual timer T1/T2 which
is adapted to be connected in circuit between the sensor 24 and
conventional counters 26 and 51 the former of which may function
in the manner of the counter disclosed in the above-noted '497 patent.
That is, counter 26 may be connected in circuit with the fuse (denoted
at F in FIG. 5) that forms part of the filter element contained
in housing 18. After counter 26 has received a predetermined number
of counts, it will function to shut down the crushing mechanism
of the apparatus shown in FIG. 1 until such time that the filter
element is replaced with a new element. In the embodiment illustrated
herein, the sensor 24 constitutes a proximity type tube sensing
switch which, by way of example, may be of the capacitive sensor
variety sold by Rechner Electronics Industries, Inc. under the article
designation number 770600. It is to be understood, however, that
other types of sensor switches, such as for example known mechanically
or optically operated switches may be employed without departing
from this invention.
The timers T1/T2 are energized from a DC 5 volt power supply through
line 31 a resistor R3 and line 32 to each of the input terminals
R/I for timers T1 and T2 respectively. Operation of the timers
is completed by connecting terminal CV of timer T1 through capacitor
C3 and line 33 to the common (negative) line 34 while the terminal
CV of timer T2 is connected through the capacitor C6 also to the
line 34. In addition to energizing the timers T1 and T2 the 5 v.
power supply is applied through line 31 to the collector terminal
of an NPN transistor TR1 and through a resistor R8 to the emitter
of TR1 and to the collector terminal of a second NPN transistor
TR2 the collector terminal of which is also connected to the emitter
of TR1. The emitter terminal of transistor TR2 is connected by a
line 35 and through a resistor R10 in line 33 to the common line
34. Also at this time the 5 v. power supply is applied by line 31
and the resistor R9 to the base of the transistor TR1 and by line
31 through a resistor R6 to the base of transistor TR2. As a consequence,
both of the transistors TR1 and TR2 are biased forwardly, so that
when the sensor switch 24 is open (OFF), current flows through the
series connected emitter/collector circuits of the two transistors,
and through line 35 resistor R10 and line 33 to ground line 34.
As a consequence, at this time line 35 and the trigger terminal
TRIG of timer T1 which is connected to line 35 are in a positive
going mode. Likewise at this time the 5 v. power supply is supplied
through line 31 resistor R6 and line 36 to the trigger terminal
TRIG of the timer T2 so that this trigger terminal also is in a
positive mode. Moreover, at this time current flow from the power
supply through line 31 resistor R4 diode D5 and resistor R5 to
line 34 causes node A of the control circuit to exhibit a positive
going mode.
In the embodiment illustrated, one side of the proximity sensor
switch 24 is connected by a line 37 through resistor R12 and the
diode D5 and resistor R5 to line 34. The other side of switch 34
is connected through line 38 and resistor R11 to line 34. A capacitor
C9 connected at one side to line 34 and at its opposite side between
resistor R12 and point A of the circuit, along with resistors R11
and R12 are utilized in this embodiment simply for the purpose
of suppressing radio frequency interference in the wires leading
to the sensing switch 24 thereby to reduce or minimize any switching
noise which might otherwise be created by such interference. Also,
resistor R1 and capacitor C1 control the duration of the output
signal produced as noted hereinafter by timer T1 (75 ms), while
R2 and C2 control the duration of the signal (500 ms) produced by
timer T2.
In any event, whenever the sensor switch 24 is closed (ON), it
effectively shunts point A through resistors R12 and R11 to line
34 whereby the voltage at point A changes suddenly from a positive
to a negative going voltage, such as for example from about 3.8
volts to approximately zero voltage. This sudden voltage change
is communicated via a capacitor C4 simultaneously to the base of
the transistor TR2 and to line 36. The negative going signal at
the base of transistor TR2 momentarily turns off the transistor
TR2 thereby creating a negative going signal via line 35 to the
trigger terminal (TRIG) of the timer T1 at the same time that line
36 applies a negative-going signal to the triggering terminal of
the timer T2. As a consequence, both the timers T1 and T2 are turned
on simultaneously, with the output terminal (OUT) of timer T1 applying
an output pulse of approximately 75 ms duration via the line 41
to the input of counter 26 at the same time that the output terminal
(OUT) of timer T2 applies an output signal of a duration of approximately
500 ms through line 42 to the anodes of diodes D3 and D4. The cathode
of diode D3 is connected to line 35 and the cathode of a diode
D4 is connected through a capacitor C5 to the base of transistor
TR1 and through resistor R5 to line 34. For the duration of the
output signal from timer T2 the diode D3 conducts, thus maintaining
line 35 in a positive going mode, thereby preventing transistor
TR2 from conducting, and in turn inhibits T1 from again being triggered
for the approximately 500 ms duration of the output signal of timer
T2. This duration is illustrated in FIG. 4 by graph E.
If the sensor 24 was closed (turned ON) by virtue of the insertion
of a short or four foot tube into the crusher, then approximately
100 to 300 ms after insertion of the tube into the crusher mechanism
the sensor switch 24 will open and the voltage of point A will return
to a positive going mode, with current now flowing through the diode
D5 and resistor R5 to line 34. As soon as the diode D5 once again
begins to conduct (at the end of the 100 to 300 ms duration) it
will cause a positive going voltage to appear at the cathode terminal
of the diode D4 thereby interrupting current flow through diode
D4 and consequently interrupting the transmission of the output
signal of timer T2 through diode D4. Therefore, by the time that
the 500 ms output signal from the timer T2 expires, only one trigger
signal will have been applied by timer T1 through line 41 to the
counter 26.
If instead of inserting a 4 foot tube into the machine, a U-shaped
tube has been fed into the machine, then within the 180 to 300 ms
that it takes for the U-shaped tube to pass through the chute 24
and beyond the sensor 24 it will be noted from the above description
that the approximate 500 ms output signal from the timer T2 inhibits
or otherwise prevents timer T1 from producing any more than a single
output signal on line 41. Thus, when the U-shaped tube is initially
inserted into chute 24 it will momentarily close or turn ON the
sensor switch 24 as shown for example by graph C in FIG. 3 and
therefore will momentarily (at least for approximately 40 to 50
ms) cause point A to drop to near zero voltage, and therefore will
trigger both the timers T1 and T2. One count signal will therefore
be applied by line 41 to the counter 26 within the initial period
of time that the sensor 24 is closed, but because of the inhibiting
effect of the 500 ms signal output from the timer T2 no additional
count signal will be applied to line 41 at any time during the overall
interval of time it takes (180 to 300 ms) for the U-shaped tube
to complete its passage beyond the sensor switch 24.
On the other hand, if instead of a short tube having been inserted
into the crusher mechanism, a long, eight foot tube had been inserted,
then the sensor switch 24 would have remained closed for essentially
anywhere from 600 to 1000 ms, so that at the time that the timer
T2 output signal expired, approximately 500 ms after the closing
of the sensor switch, point A in the circuit would still be in a
negative going mode. As a consequence, diode D5 would have no influence
upon the voltage existing at the cathode side of the diode D4 which
would now be governed by the output of timer T2. Therefore, at the
time that the output signal from timer T2 expires, voltage on line
42 and at the output of D4 will drop to nearly zero. That change
in voltage is communicated via capacitor C5 to the base of transistor
TR1 thereby momentarily interrupting the conduction through transistor
TR1. When TR1 ceases to conduct, TR2 is starved of supply voltage
at its collector terminal, thereby causing the emitter voltage of
TR2 to drop, thereby causing the voltage on line 35 to go negative,
and in turn causing the triggering terminal (TRIG) on timer T1 to
produce a second output pulse on line 41 to the counter 26. Thus,
for the eight foot tube, counter 26 received two counts. During
this interval resistor R6 maintains the base of transistor TR2 in
a positive mode, and as a consequence timer T2 is not again triggered.
After timer T1 finally runs out, and the sensing switch has opened,
the circuit returns to its initial conditions ready to repeat the
transmission of one or two count signals to the counter 26 depending
upon whether or not either a four foot or eight foot tube is crushed.
In practice it is desirable also to detect when the drum 11 (FIG.
1) has become filled, or nearly filled with crushed glass. For this
reason the count signal applied by line 41 (FIG. 5) to counter 26
may also be applied to the input of a second counter 51 which is
set to count out and energize a warning lamp 52 after a predetermined
number of four foot tubes, or equivalents thereof, have been crushed
by the mechanism of FIG. 1. Upon replacement of a filled drum 11
with an empty drum, counter 51 would be rest to zero to deenergize
lamp 52 until the new drum has been filled. |