US3818604A

US3818604A - Termination logic and output suppression for integrated circuit dryer control

Info

Publication number: US3818604A
Application number: US00400700A
Authority: US
Inventors: C Offutt; D Janke; R Marcade
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 1973-09-25
Filing date: 1973-09-25
Publication date: 1974-06-25
Anticipated expiration: 1991-06-25
Also published as: JPS5526724B2; JPS5059857A; AU7315074A; BR7407965D0; CA1027211A

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.

Description

Unite States Patent [191 Offutt et a1.

[ June 25, 1974 TERMINATION LOGIC AND OUTPUT SUPPRESSION FOR INTEGRATED CIRCUIT DRYER CONTROL [75] Inventors: Carl R. Otfutt, St. Joseph; Donald Edward Janke, Benton Harbor; Roque Denis Marcade, Stevensville, all of Mich.

[73] Assignee: Whirlpool Corporation, Benton Harbor, Mich.

[22] Filed: Sept. 25, 1973 [21] Appl. No.: 400,700

[52] U.S. Cl 34/45, 34/55, 328/72 [51] Int. Cl F26b 11/04, H03k 17/00 [58] Field of Search 34/45, 48, 53, 55; 328/72,

M6 M02 Y c o (/A/ 762 3,769,716 11/1973 .lanke et a1 34/53 Primary ExaminerWilliam F. ODea Assistant ExaminerPaul Devinsky Attorney, Agent, or Firml-lill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson [5 7] 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.

12 Claims, 6 Drawing Figures 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, tennination 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 US. 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 DC. 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 US. 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, l973 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 tennination 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. 2is 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 joumaled 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 I2 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. I, 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 LI, L2 and N. With such a commercial supply, a 230 volt potential is provided across the terminals Ll-LZ, and a I 15 volt potential is provided across the terminals LI-N. The circuit is divided such that one portion of its components is generally associated with volt operation from the terminals Ll-N and another portion of its components is associated with 230 volt operation by way of the terminals Isl-L2.

The portion of the circuit associated with the terminals Ll-L2 comprises the heater 76 which is serially connected with an operating thennostat 140, a safety thennostat 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 Ll-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 Ll-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 Ll-N. Further, a power transformer 102 is connected across the terminals Ll-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 US. 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 DC. power supply and a DC. shutdown circuit 119 to the power transformer 102. 1n 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 tothe 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 1 15 volt supply at the terminals and 101 and a secondary winding 104, a full-wave bridge rectifier 105, a diode l 10, a filter capacitor 115, an emitter-follower voltage regulator including a transistor 124 and a Zener diode 123, and DC. 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 AC. voltage applied to the primary winding 103 of the power transformer 102 from the terminals Ll-N is transformed to approximately 30 volts, rectified by the full-wave bridge rectifier 105 and diode 1 10 and filtered by the capacitor 115. Simultaneously, approximately volts A.C. becomes available at the upper terminal of the secondary winding 104. This voltage is half-wave rectified by a diode 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 DC. 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 RC. time constant of the circuit supplying base current to the transistor 124 is very short. As a result, when an interruption of the AC. 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 DC. current from the capacitor 115 is isolated from the integrated circuit 126.

Removal of the DC. voltage from the integrated circuit 126 permits the internal pulse generating network to reset for the next time the DC. voltage is applied to the control. The value of capacitor 115 is very large, for example 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 l 15 for very long periods of time. This guarantees the availability of a smooth DC. 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 US. 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 OffuttLLS. Pat., No. 3,762,064. The outputs W, W 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 m, M2 and W3 are all ls 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, then emory counter steps to its next logical state wherein M1 is a and M2 and M3 are both ls. 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 whenever the heater 76 is energized, the motor 52 must also be energized according to the logic associated with the outputs M l and M2. The next index signal Q p laces the memory coun ter in the state where W and M3 are both 1s 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 MT, 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 OR gates G9 and G9 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 US. Pat. IE 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 l the memory counter is in the set: state and the program signal outputs M1, M2 and M3 of the memory will all be 05. When both of the signals SD and CD are 0s", the memory counter is in E cleared state and the program signal outputs M1, M2 and M2 are all 1s, and when the signal SD is a 0 and the signal CD is a l the memory counter 87 is in the clocked state and free to run ormall and provide the program signal outputs M2, 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 terminationlogic would be required to provide unambiguous signals to the SD and CD inputs of the memory counter. The signal S is a l for purposes of illustrating the present invention whenever the dryer is in an ungrounded state or polarity of the dryer power connection Ll-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 l and remaining such until power is once again removed.

In operation, when e ygr 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 causes the signal SD to be a l and the suppressed outputs m, 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 l, the memory circuit 87 goes to the set (safety) status as seen in the table of FIG. 6. Accordingly, the output m must become a 0 making its inversion M3 a l by way of the inverter 3. Therefore, when the AND gate G9 receives an input 1 from the inverter 3, and assuming the signal Rto be a 1 also because power has not been removed, the output of the AND gate G9 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 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 index 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 l, and since the reset signal R will also be a l, the AND gate G9 produces a l, the OR gate G9 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 3 both be 0 and the memory counter outputs M1, M2 and M3 will each be a 1. The signal m 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 MT, however, are suppressed by the AND gates l and 2 until after three pulse counts the signal R becomes a l, 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 that the state of the inverted output M3 forces a 0 state for the output of the AND gate G9 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 It? becomes a 0 in normal termination by, in each case, feeding the output signal M 3 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 m and MW 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 m, MW and W3 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 V3 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 c2nditioned in normal operation to the off mode, the M1 output and the W2 output are both 1s" 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 W, W and m to a 0 state and latches them there whenever W 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.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. 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 dryercontrol as claimed in claim 4, wherein said internal pulse generating means is operable to gene-rate 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 dryers 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, I

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 applicationand 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.

Claims

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.

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.