U.S. patent number 3,818,604 [Application Number 05/400,700] was granted by the patent office on 1974-06-25 for termination logic and output suppression for integrated circuit dryer control.
This patent grant is currently assigned to Whirlpool Corporation. Invention is credited to Donald Edward Janke, Roque Denis Marcade, Carl R. Offutt.
United States Patent |
3,818,604 |
Offutt , et al. |
June 25, 1974 |
TERMINATION LOGIC AND OUTPUT SUPPRESSION FOR INTEGRATED CIRCUIT
DRYER CONTROL
Abstract
In an integrated circuit controlled clothes dryer a termination
logic and output suppression circuit is provided as a safety device
to control and lock the outputs of a memory counter which are
effective to control the motor, heater and master power circuits of
the dryer, so that dryer operation is positively terminated at the
end of a drying cycle and the dryer is thus prevented from
reentering an operational state at some point in a drying cycle in
response to instability of the memory counter when power is
removed. The dryer also includes a device for detecting improper
connection to the electrical supply, such as an ungrounded state,
and this device signals the termination logic in response to such a
condition to turn off the dryer. The output suppression circuit
prevents operation of the dryer motor and heater until power has
been applied for a predetermined interval upon starting and
restarting of the dryer.
Inventors: |
Offutt; Carl R. (St. Joseph,
MI), Janke; Donald Edward (Benton Harbor, MI), Marcade;
Roque Denis (Stevensville, MI) |
Assignee: |
Whirlpool Corporation (Benton
Harbor, MI)
|
Family
ID: |
23584653 |
Appl.
No.: |
05/400,700 |
Filed: |
September 25, 1973 |
Current U.S.
Class: |
34/531;
327/160 |
Current CPC
Class: |
F26B
25/009 (20130101); D06F 58/30 (20200201); D06F
34/08 (20200201); D06F 2103/38 (20200201); D06F
2105/28 (20200201); D06F 58/50 (20200201); D06F
2103/44 (20200201); D06F 2103/00 (20200201); D06F
2105/50 (20200201); D06F 2105/62 (20200201) |
Current International
Class: |
F26B
25/00 (20060101); D06F 58/28 (20060101); F26b
011/04 (); H03k 017/00 () |
Field of
Search: |
;34/45,48,53,55
;328/72,73,74,75 ;307/223R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Dea; William F.
Assistant Examiner: Devinsky; Paul
Attorney, Agent or Firm: Hill, Gross, Simpson, Van Santen,
Steadman, Chiara & Simpson
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A dryer including a control for connection to an electrical
supply, said control comprising an integrated circuit including a
memory storing a drying program, an internal pulse generating means
for generating a pulse to initialize the memory, and a termination
circuit for said control, said termination circuit comprising:
detecting means for detecting improper connection to the electrical
supply and operable to produce a corresponding signal;
a logic circuit connected between said detecting means and said
memory and responsive to said signal to set said memory to a
predetermined state wherein its outputs terminate dryer operation;
and
a feedback circuit connected between said memory and said logic
circuit for latching said memory in said predetermined state.
2. A dryer control as claimed in claim 1, wherein
said internal pulse generating means is connected to said logic
circuit and is operable to produce an initializing pulse a
predetermined time after application of power to said integrated
circuit, and
said logic circuit includes gating means connected to certain
outputs of said memory and to said internal pulse generating means
for suppressing those outputs until generation of an initializing
pulse.
3. A dryer control for connection to an electrical supply,
comprising an integrated circuit including a memory storing a
drying program, an internal pulse generating means for generating a
pulse to initialize the memory in response to application of power
to the control, and control logic reading said memory and having a
memory indexing circuit to advance the memory through the drying
program to a programmed termination indicated by a memory output,
and a termination circuit, said termination circuit comprising:
a logic circuit having a first input connected to the memory
output, a second input connected to said internal pulse generating
means, and an output connected to said memory, and responsive to
terminate operation of the dryer in response to programmed
termination and to clear said memory in response to loss of power
to the control.
4. A dryer control as claimed in claim 3, wherein
said memory has an index input connected to said indexing circuit,
a clear input, a set input, and a plurality of program signal
outputs,
said logic circuit first input is connected to one of said program
signal outputs, and
said logic circuit second input and said memory clear input are
connected to said internal pulse generating means.
5. A dryer control as claimed in claim 4, wherein said internal
pulse generating means is operable to generate an initializing
pulse a predetermined time after the application of power to the
control, and said logic circuit comprises
an output suppression circuit including gates connected to certain
of said program signal outputs and to said internal pulse
generating means for suppressing said certain outputs for the
predetermined time.
6. A dryer control as claimed in claim 5, including
detecting means associated with the dryer for sensing the status of
the dryer's connection to the electrical supply and providing a
signal indicative of when the connection is improper, and
wherein
said internal pulse generating means is operable to produce an
initializing pulse a predetermined time after the application of
power to the control,
said memory includes a set input, a clear input, an indexing input
connected to said indexing circuit, and a plurality of outputs
associated with respective dryer operational components,
said logic circuit connected between said detecting means and said
set input and responsive to an improper condition signal to
condition said memory to a predetermined state and effect
termination of dryer operation, and
a feedback circuit connected between one of said plurality of
outputs and said logic circuit for latching said memory in said
predetermined state.
7. A dryer control as claimed in claim 6, wherein said logic
circuit comprises
an AND gate having first and second inputs, and an output,
said feedback circuit connecting said first input of said AND gate
to said one output of said memory,
said second input of said AND gate connected to said internal pulse
generating means,
an OR gate having first and second inputs, and an output,
said first input of said OR gate connected to said output of said
AND gate,
said second input of said OR gate connected to said detecting
means, and
said output of said OR gate connected to said set input of said
memory.
8. A dryer control as claimed in claim 7, wherein said feedback
circuit includes an inverter.
9. A dryer control as claimed in claim 7, wherein said logic
circuit comprises a memory output suppression circuit
comprising
a resepctive AND gate for each other of said memory outputs and
having a first input connected to the respective memory output, and
a second input connected to said internal pulse generating means
whereby the respective outputs are suppressed until application of
an initializing pulse.
10. A dryer control for connection to an electrical supply
comprising:
a heater for connection to the electrical supply;
a motor for connection to the electrical supply;
a master power control circuit including contacts for controlling
the application of power from the electrical supply to the dryer
control;
a heater control cirrcuit including contacts for connecting said
heater to the electrical supply;
a motor control circuit including contacts for connecting said
motor to the electrical supply;
detecting means for providing a signal indicative of improper
connection of the control to the electrical supply; and
an integrated circuit comprising
a memory storing a drying program and advanced through a drying
program and having outputs connected to the respective heater,
motor and master power control circuits,
an internal pulse generator for generating signals in response to
the application and loss of power to the control, and
a termination logic circuit connected to said memory and to said
pulse generator and to said detection means and operable to set and
latch said memory in a predetermined state in response to receipt
of said improper connection and loss of power signals,
respectively.
11. A dryer control as claimed in claim 10, wherein said
termination logic circuit includes a feedback circuit from said
memory responsive to normal programmed drying cycle termination to
set said memory.
12. A dryer control according to claim 10, wherein said integrated
circuit comprises a memory output suppression circuit connected to
said heater and motor control circuits and to said internal pulse
generator and effective to interrupt the respective circuits
between said memory outputs and said heater and motor control
circuits until the generation of an application of power signal.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an integrated circuit dryer control, and
more particularly to a termination logic and output suppression
circuit for an ingetrated circuit controlled clothes dryer.
2. Description of the Prior Art
An integrated circuit controlled clothes dryer is disclosed in U.S.
Pat. No. 3,702,030, Ser. No. 129,008, issued Nov. 7, 1972 and
assigned to Whirlpool Corporation. The integrated circuit includes,
among other logic components, a memory which stores a program of
drying operations, and circuitry for generating a memory reset
pulse to initialize the memory at selected times, e.g. opening or
closing of the dryer door, termination and restarting of the dryer,
so that the memory is not conditioned to an arbitrary state, but is
initialized to a predetermined logic state, and subsequently
indexed as necessary.
A capacitor is utilized to provide a delay in pulse generation in
developing the reset pulse. When power is removed from the
integrated circuit, the capacitor must be completely discharged so
that the pulse generation circuits can produce the reset pulse. As
set forth by Carl R. Offutt, in his U.S. Pat. application "DC
Shutdown Circuitry for I.C. Controlled Dryer," Ser. No. 358,092,
filed May 7, 1973, and also assigned to Whirlpool Corporation, it
has been determined that, in practice, a transistor of the
integrated circuit ceases to conduct at a voltage which is
sufficient to slow the discharge of the capacitor to an extent
where reapplication of power to the integrated circuit does not, in
certain instances, permit a positive generation of a reset pulse. A
rapid succession of opening and closing of the dryer door, for
example, may not be followed by positive accurate corresponding
generation of reset pulses. This latter patent application
therefore teaches apparatus for providing positive regeneration of
reset pulses for the memory of an integrated circuit control dryer
under a variety of starting and stopping conditions. The positive
generation of the reset pulse, and the utilization of the reset
pulse provides quick removal of D.C. power supply voltage from the
integrated circuit as the memory is initialized to a state which
defines that function.
A similar integrated circuit control for a dryer is disclosed by
Carl R. Offutt in his U.S. letters Pat. No. 3,762,064 issued Oct.
2, 1973, entitled "Timer with Cycle and Time Dependent Runout for
Dryer" and assigned to Whirlpool Corporation.
A ground monitor for effecting an "off" operational condition for
an integrated circuit control of a clothes dryer is disclosed in
U.S. Pat. No. 3,708,721, issued Jan. 2, 1973 and assigned to
Whirlpool Corporation. The monitor comprises a detecting means
which includes a series circuit of resistors and a Zener diode
connected to the power leads of a clothes dryer and operates to
prevent dryer operation whenever the dryer circuit is improperly
connected to the electrical supply, e.g. whenever a reverse
polarity or ungrounded connection is made.
It has now been discovered that a memory of an integrated circuit
control is sometimes preset to an arbitrary state in response to
ripple when power is removed therefrom. Consequently, there is the
possibility of momentary energization of dryer control elements,
such as relays, resulting in unnecessary wear, and in some cases
the dryer may unexpectedly and spontaneously restart and run
through a partial drying program beginning from a point as defined
by the arbitrary memory state.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide
termination logic and output suppression for an integrated circuit
dryer control which effectively controls and latches the outputs
from the integrated circuit control when power to the dryer is
removed to prevent reenergization of operational components of the
dryer upon termination of a drying program.
Inasmuch as the integrated circuit dryer control includes a
programmer in the form of a memory, more specific objects of the
invention include forcing the memory to a particular state in
response to sensing of a condition of improper connection of the
dryer to the electrical supply; latching the memory counter in the
aforementioned particular state in response to sensing of said
improperly connected condition of the dryer or when the memory
counter has been indexed to define normal termination of a drying
program; preventing the application of energizing signals to the
drive motor and heater of the dryer for a predetermined interval
after the application of power to the integrated circuit; and
ensuring that the memory counter is cleared between dryer
cycles.
The present invention, is primarily concerned with latching the
memory counter in a particular state in order to prevent
undesirable energization of operational electrical components of a
clothes dryer.
According to the invention, an integrated circuit control for a
clothes dryer includes a termination logic and output suppression
circuit which reads the memory output, the status of power
application to the integrated circuit dryer control, and the ground
condition or line polarity of the dryer to cause a responsive
setting of the memory to a predetermined state and a latching of
the memory in that state.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, features and advantages of the invention,
its organization, construction and operation will be best
understood from the following detailed description of a preferred
embodiment thereof taken in conjunction with the accompanying
drawings, on which:
FIG. 1 is a pictorial illustration of a clothes dryer which may
utilize the present invention, the dryer being shown in a partial
fragmentary manner;
FIG. 2 is a schematic circuit diagram of an integrated circuit for
controlling a dryer;
FIG. 3 is a schematic logic diagram of a termination logic and
latch circuit constructed in accordance with the present
invention;
FIG. 4 is a binary logic table for the operational states of a
dryer as defined by a memory counter;
FIG. 5 is a truth table defining the set-clear logic for the binary
memory counter of an integrated circuit control; and
FIG. 6 is a truth table for the memory counter and the termination
logic and latch circuit according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the preferred embodiment of the invention, as illustrated in
FIG. 1, a clothes drying appliance 10 is shown as comprising an
enclosure cabinet 12 with a control console 14 thereon, housing a
control device 16 for regulating the drying operation. A control
knob 18 selectively sets the control device 16 for various drying
cycles of operation, as, for example, automatic or timed drying
cycles. The enclosure cabinet 12 comprises a horizontal top panel
20 and a horizontal bottom panel 22, a pair of vertical side panels
24, a vertical front panel 26 and a vertical rear panel 28. An
access opening 30 is provided in the front panel 26, as defined by
an axially in-turned flange 31, having a closure door 32
cooperating therewith for loading and unloading the dryer 10.
The dryer 10 further includes a drying container for tumbling
clothes, in the form of a rotatable drum 34 housed within the
cabinet 12 and extending axially from the front panel 26 to a
bulkhead 36 spaced forwardly of the rear panel 28. To encourage
tumbling action in the clothing being dried, a plurality of
circumferentially spaced baffles 78 (only one being illustrated)
are mounted on the inner surface of the drum 34. The drum 34
includes a radially inwardly extending front closure wall 41 having
an access opening 42 therein formed by means of an axially
out-turned flange 43. The flange 43 provides a forwardly-extending
bearing annulus which overlies and is suitably journaled on the
complemental flange 31 of the cabinet 12. It will be apparent from
the foregoing that the opening 42 into the drum 34 and the opening
31 in the front panel 26 are concentric and provide access into the
rotatable drum 34 from outside the cabinet 12. The drum 34 is
supported at the rear by a pair of support rollers 48 (only one
being illustrated) mounted on the bulkhead 36. A raceway or
circumferential groove 50 indented into the peripheral wall of the
rear portion of the drum 34 serves as a track for the rollers
48.
A motor 52, mounted to the bottom panel 22 in a rear corner of the
cabinet 12, rotatably drives the drum 34 by means of a drive belt
54 extending around the periphery of and in frictional engagement
with the drum 34 and around a motor pulley 56 which is mounted at
one end of a motor shaft 58. The other end of the motor shaft 58
drives a blower 60, arranged to circulate air through the drum 34.
The blower 60 is included in a warm air system 62 positioned
between the rear panel 28 and the bulkhead 36.
The bulkhead 36 serves to enclose the open-ended rear portion of
the drum 34 and provides a fixed rear wall in which to locate a
pair of spaced openings comprising an air inlet 64 and an air
outlet 66. The blower 60 draws moisture-laden air from the interior
of the drum 34 through the outlet 66, through a removable lint
screen 68 and an air duct 70 to the blower 60, and out of the
cabinet 12 through an exhaust duct 72. Air exhausted from the drum
34 is replaced by ambient air entering the warm air system 62 by
way of an intake opening in the rear panel 28 (not shown) and is
drawn through a fresh air duct 74 passing over a heater means 76
and into the drum 34 through the inlet 64. The warm air system 62
thus circulates a stream of warm air through the drum 34,
subjecting clothing placed therein to a drying environment to
remove moisture from the fabrics while the clothing is tumbled as
the drum rotates. As set forth in the aforementioned U.S. Pat. No.
3,702,030, which together with U.S. Pat. No. 3,762,064; U.S. Pat.
No. 3,708,721 and U.S. Pat. application Ser. No. 358,092 mentioned
above are fully incorporated herein by reference, the drum 34 also
includes a moisture sensor 80 which, as can be seen by referring to
FIG. 2, comprises a pair of electrodes 81 and 82 which are bridged
by the moist tumbling fabric as the clothing is being dried. The
sensor electrode 81 is connected to ground and the sensor electrode
82 is connected to a moisture sensing circuit 83. As set forth in
U.S. Pat. No. 3,702,030, the moisture sensing circuit 83 operates
to provide repetitive pulses to a counter circuit of an integrated
circuit. As the moisture content of the clothes decreases, the
frequency of output pulses of the sensing circuit increases. The
counter circuit comprises two separate counters which are toggled
by clock pulses (designated CP in FIG. 2 of the present
application) at 60 Hz derived from conventional line current. A
first of these counters is repetitively reset by the output pulses
of the sensing circuit 83 and is in turn employed to provide reset
pulses for the second counter before the second counter reaches a
predetermined count. Therefore, as the frequency of output pulses
from the sensing circuit 83 increases so that the first counter is
repetitively reset at a rate faster than it takes for it to reset
the second counter, the second counter is allowed to reach the
predetermined count, indicating that the fabric has reached a
predetermined moisture content. When the predetermined count is
reached by the second counter it operates to provide a control
signal to a memory 87 (FIG. 3) storing a drying program and which,
in conjunction with a control logic circuit, provides output
signals for the dryer as schematically represented in FIG. 2. These
control signals operate to control heater energization by way of
the output H, drive motor energization by way of the output M, and
application of power to the entire dryer control by way of the
output MPC. The control knob 18 in FIG. 1, or push buttons or the
like, operate switches which cooperate with the control logic and
the memory counter 87 to select or alter a drying program, and the
control device 16 in FIG. 1 may be considered as including all of
the integrated circuit controlling circuits, the clock derivation
circuit, etc., shown in FIG. 2.
More specifically, FIG. 2 is a schematic circuit diagram of a
control for the dryer of FIG. 1 which shows that the dryer is
connected to a power supply, for example a three-wire 230 volt
commercial supply, at terminals L1, L2 and N. With such a
commercial supply, a 230 volt potential is provided across the
terminals L1-L2, and a 115 volt potential is provided across the
terminals L1-N. The circuit is divided such that one portion of its
components is generally associated with 115 volt operation from the
terminals L1-N and another portion of its components is associated
with 230 volt operation by way of the terminals L1-L2.
The portion of the circuit associated with the terminals L1-L2
comprises the heater 76 which is serially connected with an
operating thermostat 140, a safety thermostat 141, a switch 142
centrifugally operated by the motor 52 at a predetermined speed,
and relay contacts 149 controlled by a coil 144 such that the
heater is energized by the voltage across the terminals L1-L2 when
the contacts 149 are closed and the motor reaches the predetermined
speed to close the switch 142.
The circuit associated with the terminals L1-N comprises a motor 52
serially connected with motor relay contacts 143, a normally closed
door switch 160, and master power control relay contacts 146 across
the terminals L1-N. Further, a power transformer 102 is connected
across the terminals L1-N as will hereinafter be more fully
explained. Associated with and receiving power from the power
transformer 102 and the sensor circuit 83, the sensor 80, and the
integrated circuit 126. A detailed explanation of the sensor
circuit may be held by reference to the aforementioned U.S. Pat.
No. 3,702,030. The integrated circuit 126, provides output control
signals M, MPC and H which control the conduction of respective
transistors 151, 148, 145 causing energization of respective relay
coils 150, 147, and 144. The relay coils 150, 147 and 144
respectively control closure of the contacts 143, 146, 149, whereby
the output signals M, MPC and H respectively control energization
of the motor 52, the master power control contacts 146 and the
heater 76.
In operation, manual closure of the contacts 146 through a
push-to-start button 17 on the console 14 energizes the integrated
circuit to provide the output signals M, MPC and H to cause
energization of the motor, the heater and the master power control
relay contacts 146 for operation of the dryer through a drying
program under the control of the integrated circuit 126 as
determined by a selector switch 155 in association with the control
knob 18.
The energization of the integrated circuit 126 is controlled by
circuitry associated with the power transformer 102 as is
hereinafter explained. The integrated circuit 126 is shown
connected through a D.C. power supply and a D.C. shutdown circuit
119 to the power transformer 102. In the integrated circuit 126, a
reset pulse, referenced by the output R, is generated to reset the
memory 87 (FIG. 3) to an initial state, for example to zero. If for
any reason power is removed from the integrated circuit 126 and the
reset pulse R is not produced, the memory 87 may assume a random
state. In developing the reset pulse R in the circuit 135, which
may be a gate circuit, a capacitor 130 and a transistor 136, acting
as a resistor with the gate, connected to the drain, are utilized
to provide a delay in the pulse generation. When power is removed
from the integrated circuit, the capacitor 130 must be completely
discharged in order that the circuit 135 can produce the reset
pulse R. A transistor 132 acting as a resistor is connected in
parallel with and utilized to bleed off charge from the capacitor
130 when power is removed from the integrated circuit. However, the
transistor 132 ceases to conduct at approximately 4.5 volts and,
therefore, a resistor 131 is connected in parallel with the
capacitor 130 to bleed the remaining charge from the capacitor. In
order for the pulse R to be generated after interruption of power
to the integrated circuit 126, as by the opening or closing of the
dryer door, or by the termination and then restarting of the dryer,
the voltage must be quickly removed from the integrated circuit in
order that the time required to bleed the capacitor to zero will be
available before the machine can be restarted. The circuit for
performing this function comprises the power transformer 102 which
has a primary winding 103 connectable to the 115 volt supply at the
terminals 100 and 101 and a secondary winding 104, a full-wave
bridge rectifier 105, a diode 110, a filter capacitor 115, an
emitter-follower voltage regulator including a transistor 124 and a
Zener diode 123, and D.C. shutdown circuit indicated at 119
including a resistor 121, a resistor 122 and a capacitor 120. A
resistor 111 is also included in the circuit as shown and serves
only to limit current to the counter element of the integrated
circuit.
The A.C. voltage applied to the primary winding 103 of the power
transformer 102 from the terminals L1-N is transformed to
approximately 30 volts, rectified by the full-wave bridge rectifier
105 and diode 110 and filtered by the capacitor 115.
Simultaneously, approximately 115 volts A.C. becomes available at
the upper terminal of the secondary winding 104. This voltage is
half-wave rectified by a diode 125 and is then fed to the capacitor
120 as a half-wave charging current. The charge on the capacitor
120 is then coupled to the base of the regulator transistor 124
through a voltage divider network including the resistor 121 and
the resistor 122. When at least 90 volts is applied to the primary
winding 103 of the power transformer 102, sufficient current is
delivered to the base of the transistor 124 to turn on the
transistor and maintain the Zener reference diode 123 in
conduction. This provides a regulated source of smooth D.C. from
the capacitor 115 to the integrated circuit 126. The values of the
resistors 121 and 122 and the capacitor 120 are selected so that
the R.C. time constant of the circuit supplying base current to the
transistor 124 is very short. As a result, when an interruption of
the A.C. supply voltage occurs, the charge on the capacitor 120 is
quickly exhausted and the current provided to the base of the
transistor 124 is insufficient to maintain the transistor in
conduction. The voltage on the base of the transistor falls to zero
quickly, the transistor turns off, and the D.C. current from the
capacitor 115 is isolated from the integrated circuit 126.
Removal of the D.C. voltage from the integrated circuit 126 permits
the internal pulse generating network to reset for the next time
the D.C. voltage is applied to the control. The value of capacitor
115 is very large, for example 150 microfarads, in comparison to
the capacitor 120 which may be, for example, 0.33 microfarads, and
there is no bleed resistor connected across the capacitor 115.
Consequently, when the regulating transistor 124 is turned off,
charge can be stored on the capacitor 115 for very long periods of
time. This guarantees the availability of a smooth D.C. voltage for
application to the integrated circuit 126 during periods when the
control might be subjected to a rapid succession of restarts.
Referring now to FIG. 3, the present invention performs a safety
function in that it effectively controls and latches the output
signals of the integrated circuit when power to the dryer is
removed. As set forth above, and with specific reference to U.S.
Pat. No. 3,702,030, the memory counter 87 is an element of the
integrated circuit 126 and receives, as inputs, signals Q, CD and
SD. For a detailed understanding of the derivation of the signal Q
by the circuits within the integrated circuit 126, reference may be
taken to the aforementioned Offutt U.S. Pat., No. 3,762,064. The
outputs M1, M2 and M3 of the memory counter 87 correspond
respectively to the outputs M, H, and MPC of the integrated circuit
126 and, as set forth above, these outputs respectively control the
operation of the motor, the heater, and the master power control
which includes the circuitry associated with power transformer
102.
The memory counter 87 has a standard binary logic as is illustrated
in the table of FIG. 4. In the initial state M1, M2 and M3 are all
"1's" which indicates the dry mode of machine operation wherein the
motor, heater, and master power control are all three on. Upon
receiving the input signal Q, the memory counter steps to its next
logical state wherein M1 is a "0" and M2 and M3 are both "1's".
This is an add-on mode of operation which is fully disclosed in the
just-mentioned Offutt patent. It should be noted that because of
the OR gate G9.sub.3, whenever the heater 76 is energized, the
motor 52 must also be energized according to the logic associated
with the outputs M1 and M2. The next index signal Q places the
memory counter in the state where M1 and M3 are both "1's" and M2
is a "0," signaling the cool down mode wherein the heater 76 is
deenergized and the motor 52 and the master power control are
energized. Additional index signals Q index the memory counter to
subsequent logical states as per the table of FIG. 4 and therefore
establishes the corresponding modes of operation of the dryer. When
the memory counter 87 reaches the state where M3 is a "0," the
entire machine is shut down in accordance with the circuitry of
FIG. 2.
According to the present invention, an output suppression circuit
for controlling the outputs M1, M2 and M3 of the memory counter 87
may be embodied in accordance with the termination logic
illustrated in FIG. 3. The termination logic comprises AND gates 1,
2 and G9.sub.17, OR gates G9.sub.15 and G9.sub.3, and an inverter
3. The termination logic accepts signals S, R and M3 to produce
output signals CD and SD. The derivation of the reset signal R was
fully set forth above and the derivation of the signal S can be
produced by a variety of apparatus such as detecting means 84 (FIG.
2), and is the electrical equivalent of the signal developed across
Zener diode 28 in the aforementioned U.S. Pat. No. 3,708,721. The
signal M3 is, of course, the signal M3 inverted.
The memory counter 87 is controlled by the signals CD and SD in
accordance with the table of FIG. 5. It will be noted that
according to the defined operation of the termination logic
elements as shown in table 5 the signal SD overrides the signal CD
so that whenever the signal SD is a "1" the memory counter is in
the "set" state and the program signal outputs M1, M2 and M3 of the
memory will all be "0's". When both of the signals SD and CD are
"0's", the memory counter is in the "cleared" state and the program
signal outputs M1, M2 and M3 are all "1's," and when the signal SD
is a "0" and the signal CD is a "1" the memory counter 87 is in the
"clocked" state and free to run normally and provide the program
signal outputs M1, M2 and M3 in accordance with the table of FIG.
4. It should also be recognized that the circuit elements used in
the memory counter might be chosen in such a manner as to respond
in a different manner to the logic set forth in the table of FIG.
5. If this were the case, different termination logic would be
required to provide unambiguous signals to the SD and CD inputs of
the memory counter. The signal S is a "1" for purposes of
illustrating the present invention whenever the dryer is in an
ungrounded state or polarity of the dryer power connection L1-N is
reversed, and at all other times it is a "0." The signal R becomes
a "0" upon the application of power to the integrated circuit and
remains a "0" for three pulse counts, then becoming a "1" and
remaining such until power is once again removed.
In operation, whenever the signal S is a "1" the outputs M1, M2 and
M3 are suppressed, that is the counter is in the "set" state and
each of the outputs M1, M2 and M3 is "0." This is because the
signal S at the input of the OR gate G9.sub.15 causes the signal SD
to be a "1" and the suppressed outputs M1, M2 and M3 follow in
accordance with the table of FIG. 5. Therefore, regardless of the
mode of machine operation, whenever the signal S becomes a "1," the
memory circuit 87 goes to the "set (safety)" status as seen in the
table of FIG. 6. Accordingly, the output M3 must become a "0"
making its inversion M3 a "1" by way of the inverter 3. Therefore,
when the AND gate G9.sub.17 receives an input "1" from the inverter
3, and assuming the signal R to be a "1" also because power has not
been removed, the output of the AND gate G9.sub.17 becomes a "1,"
as does the signal SD, and remains so even if the signal S later
becomes a "0." This condition is referred to as the "set and
latched (safety)" state as noted in the table of FIG. 6 and will
necessarily be held until the signal R once again becomes a "0" to
change the output of the AND gate G9.sub.17 to a "0" and the signal
SD to a "0," assuming that the signal S has become once again a
"0."
The "set and latched (normal termination)" condition will be
reached upon normal termination of the dryer cycle. As will be seen
from the table of FIG. 4, when the anti-wrinkle mode is complete,
an index signal Q indexes the memory counter to a condition where
the output M3 is a "0." This, of course, means that the inverted
signal M3 will be a "1," and since the reset signal R will also be
a "1," the AND gate G9.sub.17 produces a "1," the OR gate G9.sub.15
also produces a "1," and the signal SD becomes a "1" thereby
forcing the memory counter 87 to the "set and latched (normal
termination)" status as indicated in the last line of FIG. 6.
The "cleared" status of the memory counter 87 occurs when, as power
is applied to the integrated circuit 126, the reset signal R
becomes a "0" and remains such for three pulse counts. With this
condition of the reset signal R, the signals CD and SD will both be
"0" and the memory counter outputs M1, M2 and M3 will each be a
"1." The signal M3 goes directly to the integrated circuit output
(MPC) turning on the master power control by way of the transistor
148, the relay coil 147 and the corresponding relay contacts
146.
The signals M2 and M1, however, are suppressed by the AND gates 1
and 2 until after three pulse counts the signal R becomes a "1," at
which time the AND gates 1 and 2 are opened to provide the
respective outputs M and H from the integrated circuit 126 to turn
on the motor 52 and the heater 76. As previously explained, the
motor is energized by way of the transistor 151, the relay coil 150
and the corresponding relay contacts 143, while the heater is
energized by way of the transistor 145, the relay coil 144 and the
corresponding relay contacts 149.
At this time the memory counter 87 is conditioned to a "clocked"
status as indicated in the table of FIG. 6 because signal CD is a
"1" consistent with the signal R and the status of the signal SD is
"0" due to the fact that the "0" state of the inverted output M3
forces a "0" state for the output of the AND gate G9.sub.17.
In summary therefore, the present invention provides that the
memory counter is forced to a particular state when the grounding
and polarity safety signal S is a "1." The memory counter is "set"
or locked in this particular state whenever the signal S becomes a
"1" or whenever the output M3 becomes a "0" in normal termination
by, in each case, feeding the output signal M3 through a feedback
circuit (here including as shown in FIG. 3 an inverter 3) to a
termination logic circuit. Upon a reapplication of power to the
integrated circuit to restart the dryer the memory counter is reset
and the motor and heater outputs M1 and M2 of the memory counter 87
are interrupted and not utilized as outputs of the integrated
circuit 126 for a predetermined interval, here for three pulse
counts, while the reset signal R is a "0." The present invention
has therefore solved the problem of the tendency of the memory
counter to be unstable or to ripple when power is removed from the
integrated circuit. This feature eliminates the possibility of
random outputs of M1, M2 and M3 and the consequent possible
momentary closing of the relay contacts 143, 146 and 149.
Unnecessary wear of the relay contacts, and even unexpected
restarting of dryer operation, is thus avoided. The advantageous
utilization of the output M3 in accordance with this invention is
of particular importance where the logic of the memory counter is
as heretofore described because, as will be seen from the last line
of the table of FIG. 4, when the memory counter 87 is conditioned
in normal operation to the off mode, the M1 output and the M2
output are both "1's" and the machine shuts off only because
energization of the heater 76 and of the motor 52 are dependent
upon the master control circuit for receiving power. The circuitry
of the present invention immediately forces all three of the
signals M1, M2 and M3 to a "0" state and latches them there
whenever M3 becomes a "0."
Although we have described our invention by reference to a
particular illustrative embodiment thereof, many changes and
modifications may become apparent to those skilled in the art
without departing from the spirit and scope of our invention. We
therefore intend to include within the patent warranted hereon all
such changes and modifications as may reasonably and properly be
included within the scope of our contribution to the art.
* * * * *