U.S. patent number 3,564,960 [Application Number 04/817,452] was granted by the patent office on 1971-02-23 for automatic copy machine copy paper length error compensating system.
This patent grant is currently assigned to GAF Corporation, New York, NY. Invention is credited to Edwin D. Foulks.
United States Patent |
3,564,960 |
|
February 23, 1971 |
AUTOMATIC COPY MACHINE COPY PAPER LENGTH ERROR COMPENSATING
SYSTEM
Abstract
As an original moves forward, a trailing edge sensor sends an
initial cutting signal to a super-precise electronic timer having a
capacitor that has already received a voltage generated by the
actual speed of advance of the end portion of a strip of copy
paper, so that when a regulated voltage is applied to the
capacitor, the charging interval of the capacitor is controlled, so
that any tendency for lengths to be cut too short or too long is
corrected automatically when the capacitor discharges and thereby
produces an actual cutting signal for operating a cutter to sever
the strip. In the case of "flying" cuts, the strip speed voltage
assists, and in the case of strip "standstill" cuts, such voltage
"bucks" the charging current of the regulated voltage.
Inventors: |
Edwin D. Foulks (Lisle,
NY) |
Assignee: |
GAF Corporation, New York, NY
(N/A)
|
Family
ID: |
25223115 |
Appl.
No.: |
04/817,452 |
Filed: |
April 18, 1969 |
Current U.S.
Class: |
83/203; 83/208;
83/365; 399/385; 83/289 |
Current CPC
Class: |
B23D
36/005 (20130101); G03B 27/14 (20130101); Y10T
83/533 (20150401); Y10T 83/4455 (20150401); Y10T
83/4443 (20150401); Y10T 83/4664 (20150401) |
Current International
Class: |
B23D
36/00 (20060101); G03B 27/14 (20060101); G03B
27/02 (20060101); B26d 005/34 () |
Field of
Search: |
;83/203,205,285,286,289--292,208,360--365,369 ;355/13 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: James M. Meister
Attorney, Agent or Firm: Samson B. Leavitt Walter C. Kehm
Martin Smolowitz
Claims
I claim:
1. An automatic copy machine paper length error compensating system
for precision-timing the operation of a cutter for severing a
length from the end portion of a strip of copy paper when the
latter is advanced sufficiently for such length to be cut therefrom
to correspond to that of an original when the trailing edge of the
latter causes a sensor to produce an initial cutting signal,
comprising: a super-precise timer circuit containing a capacitor,
the charging time of which controls an interval between receipt of
such initial cutting signal and the output of an actual cutting
signal for controlling the cutting operation of such cutter; means
acting to apply to said capacitor a DC voltage the value of which
is proportional to the actual speed of advance of the end portion
of the strip immediately prior to being cut; and means acting in
response to such initial cutting signal to connect said circuit to
a regulated source of DC voltage for charging said capacitor to the
extent permitted by such strip transit speed voltage to control the
actual charging time to the capacitor, which upon discharge
produces such actual cutting signal for operating the cutter at the
precise time required for severing the strip, thereby compensating
for any error in copy paper lengths over a substantial range of
speed in strip advances.
2. The invention as defined by claim 1, in which the copy paper
strip comes to a standstill for cutting by the cutter immediately
after the advance of the end portion thereof, and the strip speed
voltage is applied to said capacitor in "bucking" relation to that
of the regulated voltage, whereby decreases in cut lengths due to
increases in paper strip transit speeds are automatically
compensated for by corresponding delay in the actual charging time
of the capacitor.
3. The invention as defined by claim 1, in which the paper strip is
cut on the "fly" while advancing, and the strip speed voltage is
applied to said capacitor in the same relation as that of the
regulating voltage, whereby increases in cut lengths due to
increases in paper strip transit speeds are compensated for by
corresponding decreases in the actual charging time of the
capacitor.
4. The invention as defined by claim 1, in which switching means
are provided for selectively applying the strip speed voltage to
the capacitor in either "bucking," or assisting relation, to that
of such regulated voltage.
5. The invention as defined by claim 1, in which means including
adjustable resistors are provided for adjusting the strip speed
voltage and the regulated voltage applied to said capacitor.
Description
This invention relates to automatic photocopy machines, and more
particularly, to copy paper handling subsystems therein.
THE PRIOR ART
Automatic photocopy machines are known which employ Diazo,
Electrostatic and other processes. For example, in one machine and
paper handling combination, a common drive motor provides
mechanical power to all elements of the machine via a common drive
linkage, such as a drive chain and associated gearing. An electric
clutch couples the drive motor to the drive chain.
After the machine is switched "ON" electrically, conveyor belts are
set into motion, and an activation subsystem is also turned "ON."
With all mechanical, optical, electrical, and chemical elements of
the machine now in operation, the machine is ready to produce copy.
An original inserted in an input tray is picked up by a conveyor
belt receiver and fed into an enclosure of the machine. A leading
edge sensor detects the leading edge of the original as it is in
transit toward the activation (or exposure) subsystem. The sensor
produces a signal which results in releasing a brake, thereby
freeing a paper reel-off roll feed device.
A few milliseconds after the release of the brake, another signal
produced by the edge sensor, results in the closure of a clutch,
transfering mechanical power to paper feed rollers. Another brake
of the damping type remains in effect to minimize any recrinkling
effect in the paper. The feed rollers reel off copy paper in the
form of a strip from the supply roll. The copy paper strip travels
into a cutting station containing a knife blade for example. The
original merges on top of the copy paper and the two are fed in the
activation device with the original between the copy paper and the
activation mechanism, such as intense light rays. As soon as the
trailing edge of the original is sensed, a cutting signal is
produced which results in the operating of the strip cutting knife
to sever a length from the strip. Such length is intended to
correspond to that of the original.
However, copy paper length undesirably varies with paper transit
speed, even though gearing within a machine is such as to maintain
a fixed ratio of copy paper roll off speed vs. original transit
speed (usually approximately 1:1). The control problem becomes more
involved as this ratio varies from 1:1. In the case of "standstill"
paper, for example, at a paper transit precutting speed of about 5
ft./min., copy paper lengths are very close to (.+-. one
sixty-fourth in.) to the original length; while at 60 ft./min.,
copy lengths may be as much as three-fourth inches (.+-. one
thirty-second in.) shorter than the original. Such trouble seems to
be due to overall slippage when the copy paper is brought to a
"standstill" and then cut.
The problem is complicated by the fact that copy lengths can also
be undesirably longer than the original as the transit speed
increases. This is particularly true when the paper is but on the
"fly," i.e., while in transit. On the other hand, when the paper is
cut after having stopped to a standstill, as pointed out above, the
copy tends to decrease in length with increases in transit speed
for the same original.
A copy paper length error compensating system is provided by the
present invention to overcome such difficulties and problems of the
prior art. The invention not only solves the problem when the paper
is cut upon being brought to a standstill, but also when the paper
is cut on the "fly." This feature if especially an advantage when
it is appreciated that in the first instance the compensation is
positive, and in the second, negative.
According to the invention, a super-precise timer circuit is
employed in the sensor signaling circuit which causes operation of
the paper cutting action at the proper instant for precise length
cutting in response to activation by the trailing edge of the
original. The time of such actual cutting relative to the signal is
set automatically by supplying to the timer circuit a direct
current, the voltage of which is proportional to the speed of
advance of the copy paper immediately prior to the cutting of each
length therefrom. In general, in the case of "flying" cuts, the
time delay is negative; and in the case of "standstill" cut,
positive. In any case, the invention provides copy paper length
error compensation automatically over a substantially wide range of
paper feed speeds, and comprises means for adjustment to suit the
peculiarities of each particular machine with which it is
incorporated, which vary with different machines.
In recapitulation, for example, a signal indicative of paper speed
is derived either from the armature of the drive motor (voltage) or
from a tachometer which follows a paper driven roller. This voltage
analogue of paper speed is divided and smoothed (as may be
necessary) and fed into the charging network of a millisecond to
one second range timer. The signal is coupled to the charging
network of the timer in such a way as to buck, or assist, the
normal charging current. This is to produce an increase, or
decrease, in time delay as speed increases. The externally biased
timer will cause solenoid drive circuitry to fire thereby passing
current to a knife solenoid which drives the knife that cuts the
paper. The time of cutting, is, thus, controlled by the paper
transit speed in addition to that of the initial cutting signal of
the sensor which is activated by the trailing edge of the original.
The actual speed of advance of the end portion of the strip of copy
paper immediately prior to cutting is under the control of means,
other than that of the present super-precise timer circuit. It is
of interest to point out that this same type of speed sensitive
timer device can also be used to vary the delay (of start) time of
the clutch which drives the copy paper roll-off. The longer the
time delay (fixed or proportional to speed), the shorter the copy
will be everything else remaining the same. In fact should a
push-pull control be desired, two such externally biased timers
could be put to good use; one for cutting control (trailing edge
action), the other for copy roll-off start control (leading edge
action).
THE DRAWINGS
FIG. 1 is a simplified block diagram illustrative of the
invention.
FIG. 2 is a similar view of a modification.
FIG. 3 is a circuit diagram of the timer circuit.
FIG. 4 is a circuit diagram of a filter circuit.
FIG. 5 a is a first part of a circuit diagram of the modification
shown in FIG. 2.
FIG. 5 b is a second part of a circuit diagram of the modification
shown in FIG. 2.
FIG. 5 c is a third part of a circuit diagram of the modification
shown in FIG. 2.
FIG. 1
As shown in FIG. 1, the leading edge of a strip 10 of copy paper is
automatically advanced at a speed selected automatically from a
substantial range of speeds in a cutting station 12 in response to
parallel movement therewith of an original 13 toward subsequent
merger in merging station 14 with a corresponding length 16 of
strip 10 cut therefrom. Such length 16 is severed from strip 10 in
response the the passage of the trailing edge of the original 13
past a sensor 18 at an edge sensing station 20. The sensor 18 also
controls the operation of a motor 22 which advances the strip 10
from a supply roll 24.
Advancing movement of the strip 10 by motor 10 drives a
tachometer-generator 26, the voltage output of which passes through
a filter circuit 28 into a super-precise timer circuit 30. The
timer circuit 30 preferably is an externally biased cutting signal
timing circuit which includes a current storage network. The timer
circuit 30 is connected to a voltage regulated direct current power
source 34 for supplying normal charging current to the current
storage network therein. The sensor 18 comprises means including a
drive circuit (which could involve an SCR, power transistor, or a
relay) 38 for applying an initial cutting signal to the timing
circuit 30 when the trailing edge of each original 13 passes the
sensor 18 in the edge sensing station 20.
The strip cutting station 12 is provided with a cutter which acts
when operated to sever a length 16 from the strip 10 corresponding
to that of the original 13 to be merged therewith for subsequent
copying. The cutter is operated when drive circuit 38 is energized
by the output of an actual cutting signal from the timer circuit
30. Operation of drive circuit 38 causes cutter energizing current
to flow to the cutter drive circuit. Thus, the cutting of lengths
16 from the strip 10 of the copy paper is automatically exactly
timed so that regardless of the speed of advance of the strip, the
lengths match those of the corresponding originals.
FIG. 2
The paper sheet 10 is advance at a preselected speed by a motor,
the armature 42 of which is connected by a voltage pickoff
connection 44 to a voltage divider (potentiometer) 46. The output
of the latter is fed to the externally biased timer 30, while a
regulated DC power supply 34 is also connected thereto. The power
supply 48 for a solenoid is connected to the input of the timer 30,
while the output thereof is fed to a solenoid drive circuit 50. The
latter is connected to a cutting knife solenoid 52 which drives the
knife 54 to sever the paper sheet 10.
In prior machines when the paper is cut after being stopped to a
standstill, the copy tends to decrease in length with increases in
transit speed for the same original. On the basis therefore, of a
copy paper being brought to a standstill then cut (or where machine
gearing is such as to tend to make copy lengths short), desirable
compensation should be positive, i.e., to increase the time delay
of the cutting action as the speed of transit increases. Following
this premise and considering FIG. 2, the copy paper error
compensation system functions as follows: The copy paper 10 is
reeled off a storage roll by means of a roll feed (or similar
feed-off device) which in turn, is driven by a DC electric drive
motor. Signal to start reeling off copy paper is dependent upon an
edge sensor which detects the leading edge of an original (to be
copied). Following this condition, copy paper is reeled off at some
speed (dependent upon a motor speed signal derived from an
automatic exposure control device).
During this interval of time from beginning of reel-off to signal
to prepare the cut copy paper (from trailing edge sensor looking at
the original), the externally biased timer 30 which is the "brain"
of the compensation system, monitors the copy paper speed via a
smoothing filter network driven by voltage picked off from the
drive motor armature 42. Armature voltage is proportioned to copy
paper speed. Depending upon the average speed of the paper, the
voltage from the armature bucks the normal charging voltage on a
timing capacitor in the timer circuit. Time delay is proportioned
to charging current which in turn, is proportioned to the net
charging voltage per unit time. Higher paper transit speeds produce
proportional or mature voltages which result in longer time delays.
After the capacitor is fully charged, the timing circuit will fire,
thereby generating a gate pulse which will fire SCRs in the
solenoid drive circuit 50. This passes the driving voltage from the
solenoid power supply 48 to the knife solenoid 52 which in turn,
drives the knife 54 thereby cutting the paper 10. Immediately
following the paper cutting, the timer 30 is reset, either from a
limit switch actuated by the knife 54 or by means of a second time
delay device.
THE TIMER CIRCUIT--FIG. 3
The details of the timing circuit 30 as follows: Basically, this is
a modification of a known circuit of the G.E. Co. SCR Manual 1967
edition, pages 165 and 166. Predictable time delays from as low as
0.3 milliseconds to over 3 minutes are obtainable from such circuit
without resorting to a large value electrolytic type timing
capacitor. Instead, a stable low leakage paper or mylar capacitor
C.sub.1 is used and the peak point current of the timing
unijunction transistor is effectively reduced, so that a large
value emitter resistor may be substituted. The peak point
requirement of transistor Q.sub.2 is lowered up to 1000 times, by
pulsing its upper base with a 3/4-volt negative pulse derived from
free running oscillator Q.sub.2. This pulse momentarily drops the
peak point voltage of transistor Q.sub.1, allowing peak point
current to be supplied from capacitor C, rather than via a
resistor. Pulse rate of Q.sub.2 is not critical, but it should have
a period that is less than .02 (R.sub.1 .times.C.sub.1). With
resistor R.sub.1 = 2000 megohms and capacitor C.sub.1 = 2 mfd.
(mylar). This circuit has given stable time delays of over 1 hour.
In the present application, stability over a timing range from 1
millisecond to 100 milliseconds is sufficient.
This simplifies the selection of R.sub.1 and C.sub.1, but increases
the pulse rate requirement of capacitor Q.sub.2 proportionally, a
C.sub.1 = 2 mfd. in mylar presents no problem, but an R.sub.1 of
considerably less than 2000 megohms is most desirable. Resistor
r.sub.2 is selected for best stabilization of the firing point over
the required temperature range. Because the input impedance of the
2N494C UJ transistor (i.e., capacitor Q.sub.1) is greater than 1500
megohms before it is fired, the maximum time delay that can be
achieved is limited mainly by the leakage characteristics of
capacitor C.sub.1. Particularly unique is the breaking of the
otherwise normal connection 50 from resistors R.sub.2 + R.sub.1 to
capacitor C.sub.1 at between points 1 and 2 and the insertion of an
external voltage across a potentiometer R.sub.3 into the time delay
circuit 30 at such points 1 and 2.
The external voltage DC is generated by the armature of motor
driving the paper feed mechanism or by a tachometer DC generator,
which monitors the paper feed shaft. This voltage which is
analogous to paper speed is applied to terminals 52-52, FIG. 4, and
smoothed by filter circuit 28, and then fed into the timing circuit
30 via terminals A, A; which terminal is positive depends upon the
action desired. If the compensation required is positive, the
polarity will be such as to buck the normal charging potential (and
associated current in the R.sub.1, R.sub.2, C.sub.1 sequence).
Should the reverse be desired, the polarity of the input leads is
reversed. Adjustability of resistor R.sub.3 permits presetting a
proportional effect.
The output pulse from the timer 30, terminals 54-54 is picked off
across resistor R.sub.8 for purposes of firing an SCR gate, or
whatever other device is associated with the input of the solenoid
drive circuit 50, FIG. 2. The absolute resistance value of resistor
R.sub.3 depends upon the input requirements of the solenoid drive
circuitry. That of resistor R.sub.8 depends upon the output
characteristics of the voltage generator and the smoothing filter
28. For the needs in this application, resistor R.sub.1 is about 10
megohms; R.sub.2 about 2.5 K; R.sub.4 and R.sub.6 about 150 ohms;
R.sub.5 about 400 K; R.sub.7 about 550 ohms; C.sub.2 about .001
mfd.; and C.sub.3 about .05 mfd. Transistor P.sub.1 is a zener
diode; Q.sub.1 is a GE 2N494C UJ transistor; and Q.sub.2, a 2 n2646
transistor.
FIG. 4
A satisfactory smoothing network comprising filter 28 is shown in
FIG. 11. Such filter includes a 10K resistor 56 in series with a
4.7K resistor 58 in line 60 between terminals 52 and A; and a 2
capacitor 62, a 4.7K resistor 64, and a 50 mfd. capacitor 66 in
parallel with each other across lines 60 and 68. Output of the
filter 28 is 20 volts (maximum) DC, with 0.04V p-pAC. Voltage is
applied to terminals 52-52, and after filtering appears across
terminals A-A.
FIGS. 5a, 5b, AND 6c
The main circuits of the blocks shown in FIG. 2 are shown in more
detail along with the connections therebetween in FIGS. 5a--5c.
Circuit 36 is typical of an edge sensing photo electric device
which has proven to be satisfactory with the timer circuit 30.
Solenoid drive circuit 50 is associated with a circuit 70 which
includes the brake and clutch circuitry. A suitable power supply
and storage device for the various drives is indicated by circuit
72.
Photo cell 71, FIG. 6a, is connected to the positive terminal of a
26 volt DC power supply by lead 73, and to the other side thereof
through a ground lead 76. The lead 73 contains series resistors 78
and 80, the latter being adjustable. Firing of the cell 71, fires
transistor 82 and energizes relay coil 74 of relay RY1, through
lead 84 from power supply 34 to ground lead 76. The transistor
firing circuit 86 includes a diode 88 and resistor 90 in rectifier
circuit 92 across the transistor control leads which contain
resistors 92 and 93.
When transistor 82 fires, relay coil 74 becomes energized and turns
switch contact 94 of the relay RYl so that it leaves contact 96 and
touches contact 98. The latter applies voltage to the clutch drive
circuitry 70, energizing the clutch coil 99 and coil 100 relays
RY2. The latter operates contacts 101 and 102, connecting leads
104, 104 from a 120 volt AC source to bridge 106 having positive
and negative DC output leads 108 and 110. The positive lead 108 is
connected to a capacitor 112 through a resistor 114 and a diode
116. The negative lead 110 is connected to the capacitor 112 and to
ground at point 114. Point 116 on the positive side is connected to
coil 118 of the knife solenoid 50, FIG. 2, at point 120. The other
terminal of the coil 118 is connected to point 122 and the latter
is connected by diode 124 and resistor 126 to the point 120. Thus,
the solenoid coil 118 is energized when transistors SCR's 123 and
125 of the solenoid drive circuit 50 are fired by a pulse from the
timer circuit 30 via lead 126. The energization of the coil 100 of
relay RY2 also opens contacts 128 to deenergize brake coil 130
having a diode 132 and resistor 134 connected in parallel
therewith. Power to the brake coil is also under the control of a
microswitch 136 on the knife 54, FIG. 2; or contacts on a time
delay contact device following a set of contacts of relay RY2.
THE SYSTEM
This system has been observed (on hundreds of samples basis) to cut
copy automatically over speed range (variable at random) to
accuracies of original length .+-..040 in. At any fixed speed of
paper transit, copy cut accuracies have been observed to be within
limits of original length .+-..015 in. A common drive motor
provides mechanical power to all elements of the machine via a
common drive linkage such as a drive chain and gear combination. An
electric clutch coupling the drive motor to drive chain is
used.
After the machine has been switched "ON" electrically, the drive
motor sets the conveyor belts, or other feed-in device (rollers,
etc.), into motion. The activation subsystem which may consist of
high intensity lamps associated with a drum, or electrostatic field
generator associated with grids, wires and/or plates is also turned
"ON." The developer subsystem is activated. This may involve the
metering of an ammonia vapor into a tank at some desired rate, or
evaporation of a developer solution, or the agitation of a
developer bath, or the application of an electric field.
Since the specifics of the particular activation (or exposure) and
developer subsystems are not in context in this disclosure,
treatment of these devices will not be in detail. With all
mechanical, optical, electrical, and chemical elements of the
machine system now in operation, the machine is ready to produce
copy. An original can be inserted into the input tray. The original
will be picked up by the conveyor belt (or roller) receiver and fed
into the enclosure of the machine. A leading edge sensor detects
the leading edge of the original as it is in transit toward the
activation (or exposure) subsystem.
This sensor can be a lever actuated microswitch, a photoelectric
device, a sonic beam device, a fluidic switch device, or a beta ray
switch. Photoswitches appear to be optimum in view of performance
versus cost considerations, although a sonic switch worked quite
well, in view of transparent originals. The signal is amplified in
and by edge sensing circuitry. This deactivates the switch function
device associated with the brake drive circuitry which releases the
electric brake thereby freeing the paper reel-off roll feed (or
similar function) device. A few milliseconds after the release of
the brake (or simultaneously with the brake release signal),
another signal is generated associated with the edge sensor which
activates the switch function device associated with the clutch
drive circuitry. This closes the clutch circuit thereby
transferring mechanical poser to the paper feed rollers.
A mechanical (strap, magnetic, spring, etc.) type damping brake
remaining in effect all the time has shown itself to be valuable in
minimizing wrinkling effect in the paper. Although not necessary
for accuracy in all machine situations, it has helped in some
specific instances. With clutch in and brake out, the paper feed
rollers reel off copy paper from the paper roll storage. This is
guided by the paper guides in the direction of the paper knife. The
copy paper travels under the knife blade in the direction of the
activation subsystem. The original merges on top of the copy paper
and the two are fed into the activation device with the original
between the copy paper and the activation mechanism (usually an
intense light source high in UV spectra).
As soon as the trailing edge of the original is sensed, the signal
to fire the knife solenoid is generated but delayed for a brief
(order of milliseconds) period depending upon the speed information
stored in the externally biased timer. Electric power from power
supply is delivered to the solenoid after the speed dependent
delay.
Speed information exists in terms of the voltage across the
armature of the main drive motor. This is fed into the timing
network of the externally biased timer. The proportional delay in
knife action compensates for copy length error due to speed
changes. The knife cuts the copy after the clutch circuitry
releases the clutch, the break circuitry powers the brake and the
speed compensation delay. When the knife blade crosses the paper
sheet with some overshoot, the system is reset by any suitable
reset circuitry.
A "READY" light comes on (for the next copy action) and the edge
sensor awaits a new leading edge. The copy having been cut proceeds
through the activation subsystem along with the original. After
activation, the original and copy are separated and conveyor belts
transport the original into an output bin for originals. The copy
is transported into the developer subsystem. After development, the
copy is conveyed into an output bin for copies.
The present invention, in effect, employs the speed of the strip to
be cut to critically present in accordance with such speed the
short time interval required between the initial signal to cut and
the actual cutting signal for obviating length errors. The paper
speed itself is regulated by means separate from the timer circuit
which controls the exact time of cutting in response to activation
of the trailing edge sensor by movement of the original as the
latter moves forwardly for subsequent merger with the corresponding
length of copy that is cut from the strip.
* * * * *