US3297923A

US3297923A - Combination switch control for servo-circuit systems

Info

Publication number: US3297923A
Application number: US308836A
Authority: US
Inventors: Emmor V Schneider; Andrew F Deming
Original assignee: Consolidated Electronics Industries Corp
Current assignee: Consolidated Electronics Industries Corp
Priority date: 1963-09-13
Filing date: 1963-09-13
Publication date: 1967-01-10
Anticipated expiration: 1984-01-10

Description

Jan. 10, 1967 E. v. SCHNEIDER ETAL 3,297,923

COMBINATION SWITCH CONTROL FOR SERVO-CIRCUIT SYSTEMS Filed Sept, 13, 1965 2 Sheets-Sheet 1 I i INVENTORS FIG.3C EMMOR v. SCHNEIDER 94 9s yANDREW EDEMING aM/fi WM Jan. 10, 1967 51 v. SCHNEIDER ETAL COMBINATION SWITCH CONTROL FOR SERVO-CIRCUIT SYSTEMS Filed Sept. 13, 1965 2 Sheets-Sheet 2 IIIIL TIL I II I I I I I I I I I I I I I I I I INVENTOR5 EMMOR V. SCHNEIDER BY ANDREW E DEMING M W M ATTORNEYS United States Patent 3,297,923 COMBINATION SWITCH CONTROL FOR SERVO-CIRCUIT SYSTEMS Emmor V. Schneider and Andrew F. Deming, Alliance, Ohio, assignors to Consolidated Electronics Industries Corporation, a corporation of Delaware Filed Sept. 13, 1963, Ser. No. 308,836 Claims. (Cl. 318-18) This application is a continuation-in-part of our application Serial No. 300,838, filed August 8, 1963 and entitled Phase Sensitive Circuit and now abandoned.

The invention relates in general to antenna rotator devices or other servo-circuit systems having a motor for turning an antenna or other element which may be operated to any one of a plurality of places in a range between first and second rotational limits, and more particularly to a switching control system for controlling the operation of the motor.

An object of the invention is the provision of a switching control system which avoids the necessity of employing expensive and involved relays.

Another object is the provision of a switching control system whereby the power for energizing the system may be controlled by a single pole single throw relay and whereby the circuits which establish the direction of rotation, clockwise or counter-clockwise, in which the motor is to be operated may be controlled by a single pole double throw relay.

Another object is to provide for establishing circuits to control the direction of rotation in which the motor is to be operated and for withholding the energization of the motor until such circuits are established.

Another object is the provision of a switching control system which provides for making full voltage and power available for pulling in the relays to their correct selective position and which prevents the motor from starting until after the selection has been completed.

Another object is the provision of a hold-in relay which when energized provides for maintaining energization of the complete system including the hold-in relay itself.

Another object is the provision of a switching control system which prevents needless false starts of the motor in the Wrong direction.

Another object is the provision of a switching control system Where no combination of relay operation can short the relay contacts across the motor capacitor.

Another object is the provision of a switching control system which is completely shut down or de-energized when the motor has completed its travel as called for by the setting of the control knob.

Another object is the provision of a switching control system in which the direction of rotation of the motor, clockwise or counterclockwise, is controlled by a single pole double throw relay, normally biased to make engagement with one of the two switching contact positions thereby normally causing the motor to operate in one direction, for example, clockwise, whereby, in the event the control knob is set to a new position calling for the motor to run in said clockwise direction, the system prevents or precludes the relay from being operated since the relay is already in the correct position for such clockwise rotation, and whereby, in the event the control knob is set to another new position calling for the motor to run in an opposite direction, counterclockwise, the system then provides for operating the relay so that engagement is made with the other of said two switching contact positions to cause the motor to operate in the counterclockwise direction, taken in combination with lost-motion switching means controlled by the control knob to pre clude the starting of the motor until such relay switching is completed.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a switching control system embodying the features of the invention, portions of the servo-circuit system being shown in block diagrams;

FIGURE 2 is a diagrammatic view of a switching control system showing all of the electrical circuits of the servo-circuit system;

FIGURE 3 (including 3A, 3B, 3C and 3D) is a graph of voltage and current conditions explaining the operation of the circuit of FIGURE 2; and

FIGURE 4 is a modified diagrammatic view of the switching control system.

The invention will be described with reference to an antenna rotator device but it is understood that the invention may be embodied in any other servo-circuit system.

With respect to FIGURE 1, the switching control system is arranged to operate a motor 12 which turns an antenna 36 as called for by the setting of a control knob 88 having a scale or indicia 89, N., E., S., W., indicating the direction in which the antenna is to be turned. The control knob 88 upon being actuated is arranged to start and stop the motor at any one of a plurality of places in a range between first and second rotational limits. The system generally comprises a servo-circuit means or phase sensitive circuit indicated generally by the block diagram 11, a motor circuit means indicated generally by the

conductors

26 and 27, a hold-in relay 55, a motor switching relay 3.0, and a transformer 13 for energizing the system, the transformer being energized from a supply source 19 through

feed line conductors

37 and 38,, The transformer 13 has a primary winding 18 and a secondary winding 22 having

end terminals

41 and 42 and a center tap terminal 43 for energizing the servo-circuit means, and a secondary winding 21 for energizing the motor circuit means. A lamp 23 may be provided to indicate that the secondary winding 21 is energized.

The servo-circuit means 11 comprises generally, an amplifier circuit means indicated by the block 15, first and second directional current flow devices indicated respectively by

blocks

62 and 63, and a bridge circuit including at least first and second bridge means indicated respectively by the

blocks

46 and 47. The amplifier circuit means, the directional current flow devices, and the bridge circuit of the servo-circuit means are all electrically connected together to perform the required servo-circuit operation, and are shown in block diagrams in order that attention may be focused on the switch control system. The hold-in relay 55 is energized through a first circuit, referred to hereinafter as first circuit connection means, which extends from the amplifier circuit means 15 through a conductor 59, the winding of the relay 55 and conductor 60 to the first directional current flow device 62. The hold-in relay 55 has a hold-in line contact in the feed line conductor 37 and upon energization of the relay 55 the holdin line contact 85 is closed to energize the transformer and the entire system, including the relay 55 itself. The contact 85 when once closed maintains the system energized including the relay 55 itself.

The motor switching relay 30 has a movable contact 29 which operates between first and second

opposed contacts

31 and 32. The relay 30 is normally de-energized and under a de-energized condition the movable contact 29 is making engagement with the first contact 31 that establishes a first motor circuit which extends from the secondary winding 21 through conductor 27, a disabling motor switch 28, contacts '29 and 31, conductor 33, motor winding 24, and conductor 26 back to the opposite terminal of the secondary winding 21. The first motor circuit is adapted to'cause the motor 12 to run in a first direction,

clockwise, for example, towards the first rotational limit. When the relay 30 is energized, themovable contact 29 makes contact with the second opposing contact" 32 that establishes a-second motor circuit which extends from the secondary winding 21 through the conductor 27, the

disabling motor switch 28, contacts'29 and 32, conductor 34, motor winding 25, and the conductor 26 'back to the opposite terminal. of the secondary winding 21. The second motor circuit is adapted to cause the motor 12 to run in a second direction, counter-clockwise, towards the second rotational limit. A motor capacitor 35 is connected between the first contact 31 and the second contact 32. A relay capacitor 66 is connected across the winding of the relay 55 and a relay capacitor 67 is connected across the relay winding 30. The winding of the relay 30 is in series with the winding of the relay 55 and these two relays jointly are energized through a second circuit, referred to hereinafter as second circuit connection means, which extends from the amplifier circuit means 15 through conductor 59, the winding of the relay 55, conductor 64, the winding of relay 30 and through conductor 65 to the second directional current flow device 63.

The control knob 88 may be set at any one of a plurality of positions in a range between first and second limit positions and is adapted to have lost-motion means 86 and 87, illustrated as a yoke-86 and a pin 87, therebe tween. The control knob 88 moves the'first bridge means 46 through this lost-motion means '86-87. The bridge means 47 is driven by the motor 12. When the two bridge means are balanced, there is produced a null electrical condition which de-energizes the. relay 55 and, in turn, the entire system. The lost-motion means 86-87'is initiated during the first few degrees of rotation and is adapted to temporarily open a disabling motor-contact 28 in the motor circuit and to close a line contact in the feed line conductor 37. Continued rotationv of the knob 88 operates the first bridge means 46 to cause an unbalanced electrical condition with the bridge means 47 which is driven by the motor 12. Release of the knob 88, after it has been rotated to its desired newsetting, causes the lost-motion means 86-87 toreclose the disabling motor contact 28 and reopen the line contact 20.

Thus, in actuating the knob 88 to a particular setting, the disabling motor contact 28 is temporarily opened and the line contact 20 is temporarily closed, which in actual practice may be one or two seconds, which is much larger than the fractional part of a second required to energize the relays.

In explaining the operation of the system, let it be assumed that the knob 88 is turned in a first direction (clockwise) calling for the motor 12 to turn clockwise. The initial turning of the knob 88 causes the lost-motion means 86-87 to open the disabling motor contact 28 and close the line contact 20. The tempo ary closure of the line contact 20 energizesthe primary winding 18 of the transformer 13 and the

twosecondary windings

22 and 21, which energize respectively the servo-circuit means and the motor circuit means. The energization of the for preventing the motor from starting until after the selection has been completed, thus preventing needless false starts of the motor in the wrong direction. In antenna rotator devices, meeting Underwriters Laboratories requirements, the motor itself is designed to run on 30 volts AC. or less'and this islprovided by the transformer which is of a step-down type. The motor load may. be approximately 80 watts and this reduces the transformer voltage by about 15 percent, which in turn reduces the power developed by the amplifier circuit means 15 by about 28 percent as compared to the power which would be developed from the same circuit without the motor load. Thus, the temporary opening of the disabling motor contact 28in the motor circuit makes full voltage and power available-for pulling in the relays.

As previously pointed out, when the knob 88 has been set to its'new clockwise position, the bridge means 46 is caused to be in an electrical unbalanced condition with respect to the motor-driven bridge means 47. Release of the knob 88, after it has once been set at its new clockwise position, causes the lost-motion means 86-87 to reclose the disabling contact 28 and reopen the line contact 20. The opening of the line contact 20 does not affect the operation of the system, because by now the hold-in parallel contact 85 has been closed. The closure of the disabling motor contact 28 energizes the motor I circuit. The unbalanced electrical condition caused by turning the bridge means 46 creates a first phase condition whereby the relay 55 is energized through the first circuit connection means extending from the amplifier means 15, the conductor 60, to the directional current 30 is precluded from being operated under this first phase servo-circuit means energizes the relay 55 which closes the hold-in contact 85 for maintaining the system energized. The opening of the disabling motor contact 28 condition, it remains de-energized, leaving the movable arm 29 where it was, that is, normally biased against the contact 31, which aligns the motor to run in a clockwise direction. In other words, the relay 30 was already in its correct position for causing the motor to run in a clock-' at a place called for by the new-clockwise setting of the control knob 88 upon the de-energization of the complete system. I

Now let it be assumed that the knob 88 is turned in a second direction, counter-clockwise, to another new selection position calling for the motor to run counter-.

clockwise. In turning the knob 88 counter-clockwise, the lost-motion means 86-87 opens the disabling motor contact 28 and closes the linecontact 20, the knob performing the same operation as it did when it was turned clockwise. The closing of the line contact 20 energizes the complete system and the opening of the disabling motor contact 28 de-energizes the motor, the same as previously explainedwhen the knob was turned clockwise. However, the turning of the knob in a counter-clockwise direction actuates the bridge means 46 in a reverse direction and this establishes a reverse unbalanced electrical condition with the motor-driven bridge means 47, creating a second phase condition just the reverse from the first phase condition which was created when the knob was turned in a clockwise direction. Under this second reversed phase condition, both the relays 55 and were energized through the second circuit connection means extending from the amplifier means 15, the conductor 59, the winding of relay 55, conductor 64, the winding of relay 30 and through conductor 65 to the second directional current flow device 63. Under the second reversed phase condition, the directional current flow device 62 is open circuited and thus the relay 55 is precluded from being energized through this directional current flow device 62 as it was before when the knob was turned in a clockwise direction. Energization of the hold-in relay 55 closes the hold-in line contact 85 which energizes the entire system as explained before. However, ener-gization of the motor switching relay 30 causes the movable contact 29 to swing to its opposite position and make engagement with contact 32, aligning the motor to run in a counter-clockwise direction, as called for by the setting of the knob in a counter-clockwise position. Counterclockwise operation of the motor causes the bridge means 47 to be moved to a balanced condition with the bridge 46. The rebal-ancing of the two bridge means 46 and 47 establishes a null electrical condition which causes the amplifier 15 to decrease its conduction, thus de-energizing the relay 55, whereupon the entire system is de-energized upon the opening of the hold-in line contact 85. The motor 12 is thus stopped at a place called for by the new counter-clockwise setting of the control knob 88 upon the de-energization of the complete system.

The capacitor 67 across the relay 3% is of a larger capacity than that of capacitor 66 across the relay '55. The capacitor 67 having a longer time constant, assures that the relay 55 will be the first to pull in and the first to drop out. Thus, it is the opening of the line contact 85 that de-energizes the motor circuit along with the entire system and not the contacts of the relay 30. This assures that the entire circuit will be de-energized before the movable contact 29 of the relay 30 is changed back to make its normal engagement with the contact 31 upon de-energization thereof. Thus, there will not be any last minute reversal of the motor just as the complete system is de-energized.

In this invention, single pole relays are used with a cost saving, and no combination of relay operation can short the contacts arross the motor capacitor. The system is completely shut down when the end of motor travel is reached as called for by the setting of the knob. A great saving in the life of the relay 30 is effected because it is only operated on half the starts, namely, in counter-clockwise direction, but because of the disabling motor switch 28, no false direction is initiated. Regardless of direction of unbalance of bridge means, the relay 55 is closed.

The servo-circuit means 11 may be of any suitable design. The amplifier means may employ tubes, transistors, or any other amplifier devices. The directional

current flow devices

62 and 63 may comprise diodes, or any other such devices. The bridge means 46 and 47 may comprise suitable potentiometers, or like devices.

The circuit of FIGURE 2 shows a preferred embodiment of a switching control system showing all the electrical circuits for the servo-circuit means, applied for purpose of explanation only, to an antenna rotator. The electrical parts or elements of FIGURE 2 which correspond to like parts in FIGURE 1 are identified by the same reference characters. FIGURE 2 shows a servocircuit or phase sensitive circuit 11 used to control the motor 12. The circuit of FIGURE 2 includes, generally, the transformer 13 energizing the motor 12 and additionally a bridge circuit 14 and an amplifier circuit 15. As in FIGURE 1, the transformer 13 has a primary 18 energized from an alternating voltage source 19 through feed or

line conductors

37 and 38 controlled'by the line contacts 20. The transformer has first and

second secondaries

21 and 22 with the first secondary 21 energizing the pilot lamp 23 and connected to energize

motor windings

24 and 25. A conductor 26 extends from the secondary 21 to a common terminal of the

motor windings

24 and 25 and a conductor 27 extends from the other end of the secondary 21 through the normally closed contacts 28 and through the single pole double throw contacts 29 of relay 30 selectively through

contacts

31 and 32 and through

conductors

33 and 34 selectively to the

motor windings

24 and 25. A capacitor 35 is connected across the

conductors

33 and 34 to provide a leading or lagging phase current to the motor winding 25 relative to motor winding 24. By this means the rotor of the induction motor 12 may be rotated selectively in either direction to rotate an antenna 36 as representative of a load.

The bridge circuit 14 is energized from

end terminals

41 and 42 of the transformer secondary 22, which secondary also has a mid tap 43. The bridge circuit 14 also includes a first impedance 4-4 and an output terminal 45 and first and

second potentiometers

46 and 47 connected in series across the

end terminals

41 and 42. Thus, the first impedance 44 is a first leg of the alternating current bridge 14 and the first and

second potentiometers

46 and 47 connected in series by

conductors

48 and 49 constitute the second leg of this bridge. The two halves of the secondary 22 may be considered as the voltage source for the bridge plus the third and fourth legs of this bridge as Well. The mid tap 43 is, thus, the second output terminal of this bridge. All five conductors, 2'6, 33, 34, 48 and 49 may pass through a terminal strip 50 and thus it will be seen that the antenna rotator or load motor 12 may be remotely connected to the phase sensitive or servo-circuit 11 by a five-conductor cable.

The

output terminals

43 and 45 supply a phase sensitive input signal to a common amplifier, in this case shown as a transistor 54, as a part of the amplifier circuit 15. The motor 12 is a load responsive to two different phase conditions and is controlled through the relay 30 and a relay 55'.

The transistor 54 has a base 53, an emitter 56 and collector 57. The emitter 56 is connected by a conductor 58 to the mid tap 43. The collector 57 is connected by a conductor 59 through the coil of the relay 55, a conductor 60, a voltage dropping resistor 61 and through a first directional current flow device or diode 62 to the first end terminal 41. The collector 57 is also connected through the conductor 59, the coils of

relays

55 and 30 in series by means of a conductor 64 and a conductor 65 through a second directional current flow device or diode 63 to the end terminal 42. Filter capacitors 6'6 and 67 are connected across the coils of

relays

55 and 30, respectively.

The first and

second diodes

62 and 63 supply a DC. voltage by means of

filter resistors

68 and 69 connected in series across the anodes of the

diodes

62 and 63. The junction 70 between the

resistors

68 and 69 is connected through a filter capacitor 71 to the mid tap 4 3. The polarity of the

diodes

62 and 63 makes the junction terminal 70 negative relative to the mid tap 43. The base 53 of the transistor 54 is connected through a coupling capacitor 72 and a resistor 73 to the terminal 70.

A transistor pre-amplifier 76 may be provided in the amplifier circuit 15 for added sensitivity. Although such pro-amplifier may be omitted Where coarse control is sufficient or where an impedance matching transformer is used. The bridge output terminal 45 is connected through a current limiting resistor 77 to the base 78 of the transistor 76 and the emitter 79 of the transistor 76 is connected to the mid tap 43, which is the other output terminal of the bridg Accordingly, the bridge output is applied to the input electrodes of the transistor 76. The collector 80 of the transistor 76 is connected to a terminal '81 at the junction of capacitor 72 and resistor 73. Accordingly, the output circuit of the transistor 76 may be traced from the positive direct current source terminal 43 through the emitter 79, the collector '80 and the resistor 73 to return to the direct current source negative terminal 70. Accordingly, resistor 73' is the load .resistor of the pre-amplifier transistor 76 and is the source of input signals supplied through the coupling capacitor 72 to the main transistor amplifier 54.

The relay 55 actuates hold-in line contact 85 which is normallyopen and which is in parallel with the line switch contact 20, to, maintain the transformer 13.energized after energization of the relay 55. The first potentiometer 46 maybe the control potentiometer and is one example of a variable impedance which controls the phase of the input signals. The movable blade. of this first potentiometer 46 is moved through a lost-motion means depicted as .a yoke 86 anda pin '87 therebetween. Amanual control knob 88 moves the potentiometer 46 through this lost-motion means 8 6457. The knob 88 may cooperate with a scale or other indicia. 89 to indicate the desired rotational direction of the motor-driven antenna 36. The lost-motion means 86-87 may take one of many forms. For example, itmay be the same as shown in the co-pending application Serial No. 100,152 entitled Remote Control Device, filed April 3, 1961, now Patent No. 3,126,506, issued March 24, 1964. Movement of the knob "88 first takes up the lost motion and then rnoves the movable blade of the potentiometer 46. As the lost-motion means 8687 is actuated, the

switch contacts

20 and 28 are actuated. This movement opens the disabling motor switch contact 28 and closes line contact 20, and release of the knob 88 performs the opposite function, namely, to close the disabling motor contact 28 and open the line contact 20. The motor 12 is connected to drive the second potentiometer. .for a follow-up or closed loop servomotor system. Y

The circuit of FIGURE 2 may be operated by grasping the manual knob 88 and moving it to a new selected position, for the antenna 36. The potentiometer 47 may be the type which will permit a full 360-delgree rotation and alternatively, the potentiometer 47 may be of the ordinary type of about SOD-degree rotation between stops of the potentiometer 47. Assume that the antenna is oriented towardthe east and the knob 88 is grasped and rotated clockwise, as per'arrow 96, to the south position. This movement of the knob 88 opens the. disabling motor switch contact 28 and closes the line switch contact 20 by means of the lost-motion connection 8687 before the potentiometer46 is moved. This lost 'rmo-tion may be only one to three degrees, for example, just suflicient to actuate the

switches

20 and 28. The closing of the first line switch contact20 energizes the primary 1 8 and the entire transformer 13. The opening of the'disabling motor switch contacts 28- prevents enengization of the motor 1 2-at this time. The energization of the transformer sec ondary 2 2 energizes both the bridge circuit 14 and the amplifier circuit 15. The clockwise movement of potentiometer 46 decreases the resistance thereof and hence decreases the impedance in this second leg of the bridge which includes

potentiometers

46 and 47. Accordingly, the alternating current bridge 14 will have an output voltage at

terminals

43 and 45. This output voltage will either be in phase with the voltage from mid tap 43 to terminal 42. In this case, with the decreasing resistance of potentiometer 46, the potential of terminal 45 will shift in phase to the right, and hence the voltage from mid tap 43 to terminal 45 will be in phase with the source voltage from mid tap 43, to end terminal 42. FIGURE 3A illustrates the voltage curve91 of the voltage of terminal 41 relative to terminal 42, as a reference. Thus, when terminal 41 goes positive, the output terminal 45 will go negative because this output signal is directly out of phase with the voltage from

terminals

42 and 41. This condition is illustrated in the.left half of FIGURES 3A- 3D and the output signal 92 of the bridge is illustrated in FIGURE 3B. This is shown as being out of phase with the reference'voltage-91,whichz-is the voltage from terminal 42 to, terminal 41. Thus, in the first half cycle, when terminal 41 is positive terminal 45 goes negative. This applies a negative bias to the base 78 of transistor 76 causing this transistor to increase conduction through the load resistor 73. This transistor current is shown in FIGURE 3C as curve 93. The terminal 81 thus becomes v ducting state.

8 increasingly positive on this half cycle and, hence, the transistor 54 is biased into complete non-conduction.

A bias resistor 82 is connected between the base 78 of transistor 76 and terminal 70. This provides a small leakage current so that transistor 76 is biased into a partially conducting region. A self bias resistor 83 is connected between the base 5-3 and emitter 56 of, transistor 54, with transistor 54 normally biased in a substantially non-con- This transistor 54 is normally biased by resistor 83 as a self bias resistor, and hence, the normal condition of this transistor 54 is substantially a non-conducting condition. During the next half cycle of the reference voltage 91, however, the bridge output voltage at terminal 45 is going positive and this decreases the conduction of transistor 76 to make the terminal 81 less positive or more negative. This more negative voltage swing is applied through the coupling capacitor 72 to the base '53 of transistor 54, hence biasing it into a conducting state. The current through the main transistor 54 is shown as curve 94- in FIGURE 3D. Accordingly, a half wave pulse of current 94 is passed by the transistor 54 in the second half cycle of the reference voltage 91. This half wave pulse of current passes through the first circuit connection means including collector 57 and through the coil of relay 55, the voltage dropping resistor 61 and diode 62 to the terminal 41 which is'at that time negative. Current cannot flow through the second circuit connection means from the collector 57 through the two relay coils 55 and 30 in series to the terminal 42 because it is atthat time positive and the path is open circuited by diode 63. The capacitor 66 across the coil of the relay 55 smoothes these half wave pulses to maintain this relay 55 energized. The hold-in line contact 85 of this relay 55 is thus closedto maintain energized the transformer r13. At this time the knob 88 may be released and this will open the line contact 20 but this has no effect on the circuit since in the practical case, the relay 55 will be energized in less than second after movement of po tentiometer 46 to unbalance the bridge circuit 14.

The relay 30 has not as yet been energized, hence the closing of the disabling motor contact 28 establishes a motor energization circuit directly to motor winding 24 with leading current supplied through capacitor 35 to the motor winding 25. Accordingly, the motor 12 will run in a clockwise direction to rotate the antenna 36 to the desired south orientation. Also the potentiometer 47 is rotated clockwise to increase the resistance thereof and upon rebalance of the bridge circuit14, the output voltage of the bridge fallsto a null and thus the relay 55 will become de-energiz'ed to open the hold-in line'contact 85 and de-energize the complete circuit 11. This will be where the antenna '36 has been positioned to" the desired orientation as established by movement of the poitentiometer 46 in this clockwise direction.

Now assume that the potentiometer 46 is moved counter-clockwise, as shown by arrow 97 in FIGURE 2 and by the right half of FIGURE 3. This counter-clockwise movement increases the resistance of potentiometer146,

:This shifts the phase of the terminal point 45to the left,

that is, the bridge output voltage from terminals 43 to 45 is in phase with the voltage from terminals 43 to 41 of the reference voltage 91. FIGURE 3B shows this voltage curve 92 now as being in phase with the reference volt- "age'91of FIGURE 3A. AS the potential of terminal 41 .93 in the right half of FIGURE 3C. This decreasing cur-' rent through transistor 76 decreases the current through.

the load resistor 73 and hence the potential of terminal 81 is less positive or more negative. This more negative swinging voltage is applied through coupling capacitor 72 to the base 53 of transistor 54 to thus cause conduction of this transistor 54. This is shown by the pulse of current 95 in FIGURE 3D. This current pulse is in the first half cycle of .the reference voltage. This pulse of current is passed through the transistor 54 and goes through the second circuit connection means from collector 57 through the two relay coils 55 and 30' in series and through the diode 63 to the terminal 42 which is negative in that half cycle. The

capacitors

66 and 67 smooth this half cycle pulse of current to cause continuous energization of the

relays

30 and 55.

As before, the energization of relay 55 closes its contact hold-in line 85 to maintain the entire circuit 11 energized. The energization of relay 30 moves the contact arm 29 to energize the contact 32 and this energizes the motor winding 25 directly and the motor winding 24 with a leading current through the capacitor 35. This is another way of saying that in this energization condition, the motor winding 25 has a lagging current relative to that current through motor winding 24. This is the reverse energization condition to that established with clockwise rotation of potentiometer 46, and accordingly, the motor 12 will rotate counter-clockwise to drive the antenna to its newly selected position. This also drives the potentiometer 47 in a counter-clockwise direction to rebalance the bridge by decreasing the resistance. Again, upon rebalance of the bridge, the null condition will be achieved at the

bridge output terminals

43 and 45 which will cause cessation of current conduction through transistor 54 and de-energization of the relays 55- and 30. De-energization of relay 55 de-energizes the entire circuit and tie-energization of relay 30 permits its return to its normal condition engaging contact 31. Capacitor 67 may be made of a larger capacity than capacitor 66. This will achieve a longer time constant and will assure that the relay 55 will be the first to pull in and the first to drop out. Since relay 30 will be the last to drop out, this means the hold-in line contact 85 of relay 55 is the switch which actually interrupts the current and

relay contacts

31 and 32 will not interrupt the current; hence, this may be made a light duty relay for economy. Also, this assures that the entire circuit will be de-energized before relay 30 changes its contact condition. Thus, there will not be any last minute reversal of the motor 12 just'as the circuit is de-energized.

Additionally, the disabling motor switch 28 perfiorms a desirable function of preventing energization of the motor 12 until the motor direction of rotation has been established. Both the

relays

55 and 30 will be energized within about second after movement of the potentiometer 46 in a counterclockwise direction. Alternatively, if the potentiometer 46 is rotated clockwise, only relay 55 is energized, as set forth above. Either of these two energization conditions occurs within the aforesaid second and, hence, the motor direction of rotation is established within this short period of time after movement of the potentiometer 46. Accordingly, after the knob 88 is moved to the desired new position for the antenna 36, this knob 88 may be released at any time after this second and the motor direction of rotation will already have been established. This prevents the motor from starting rotation in one direction and then changing direction immediately thereafter should the relay 30 pull in after the motor started rotating in the opposite direction. Thus, this disabling motor switch 28 provides this desirable function of preventing false initial direction of rotation of the motor 12.

Accordingly, the above description shows that the input may have two different phase conditions. With the first phase condition of the input, only relay 55 is energized and with the second phase condition of the input,

both

relays

30 and 55 are energized. Both of these phase conditions are amplified by the common amplifier 54 but separate circuit paths are provided from this transistor 54 to the voltage source of the secondary 22. One such circuit path is through relay 55 alone and diode 62 and the other circuit path is through the two

relays

55 and 30 in series and the diode 63. These two different relay energization conditions establish two different directions of rotation of the motor 12. Accordingly, it will be seen that the transistor 54 is connected in two separate paths of difierent phase responsive character so that phase reversal of the input from the bridge 14 causes phase selective current flow in the two separate circuit paths. Further, it will be seen that when the input signal to the amplifier is of one phase characteristics, the motor will operate in one direction and when the input signal is of another phase characteristic, the motor 12 will operate in the other direction, both as established by the two separate circuit paths from the common amplifier 54.

FIGURE 4 shows a modified phase sensitive or servocircuit 151 quite similar to that shown in FIGURE 2. This circuit 151 incorporates an amplifier circuit 155 again similar to that shown in FIGURE 2, except for changes in the relay circuit which is the load for the main amplifier 54. This amplifier circuit 155 supplies energy to two relays, 161 and 162. The relay 162 is similar to the relay 55 of FIGURE 1 to control contacts for the pri mary energization circuit, since this relay 162 is always energized whenever the bridge output voltage is being conducted through transistor 54. Relay 161 is similar to the relay 30 in FIGURE 1 to selectively control energization to the

motor windings

24 and 25 for selected direction of rotation. In such a modified circuit, the relay 161 is connected from the collector 57 of transistor 54 through a conductor 164 to coil of relay 161, and conductor 165 through diode 62 to the voltage source terminal 41. Capacitor 66 is connected across the coil of relay 161 to maintain this relay closed even though energized with half-wave pulses. The coil of relay 162 is connected from the collector 57 of transistor 54 by means of conductors 164 and 169, and a conductor to the negative direct current voltage source terminal 70. In this circuit of FIGURE 4, relay 161 controls a double throw contact 171 and constitutes a reversing switch for the motor 12. The relay 162 controls a single throw contact 172.

Conductor 27 leading from the secondary 21 leads to the contact 171 and the opposed contacts are connected respectively to the

motor windings

24 and 25 through

conductors

33 and 34. The contact 171 is normally biased to energize motor winding 25 when the relay 161 is de-energized. The relay contact 172 is connected in the energization line from the alternating current voltage source 19 to the primary 18 and is connected in parallel with the manual switch contacts 20. The amplifier circuit 155 is shown as having a slightly different direct current voltage circuit from that shown in FIGURE 2. A diode 175 replaces the resistor 68 and resistor 69 is eliminated. This shows that the direct current voltage source developed across the filter capacitor 71 may be obtained by a half-wave rectifier rather than a full-wave rectifier. Also, the diode 175 in replacing the resistorv 68, provides an additional function of preventing leakage current which might otherwise flow through transistor 54. If the resistor 68 of FIGURE 2 were retained in FIGURE 4, leakage current could flow through transistor 54, through relay coil 161, through resistor .68, through the direct current voltage source and return to the emitter of transistor 54. If the transistor 54 leaked enough current during its normally non-conducting periods, this might possibly cause energization of relay 161 at undesired phase portions of the reference voltage. Use of this diode 175 prevents such occurrence.

The circuit of FIGURE 4 operates in a manner similar to that for FIGURE 2. It will be noted that the two

relays

161 and 162 operate on different phase characteristics of the input. Relay 162 actually operates from direct current and relay 161 operates on half-wave pulses supplied when terminal 41 is negative and when the input signal is in phase with the second half cycle of the reference voltage. Thus, it will be seen that there are two separate circuit paths from the transistor 54 to voltage source means with difierent phase responsive characteristics sothat phase reversal of the input causes phase selective current flow in said separate circuit paths. If the manual knob 88 is moved clockwise, this opens switch 28 and also moves the potentiometer clockwise in the direction of the arrow 6. This decreases the resistance and shifts the phase of the point 45 to be in phase with the voltage from terminal 43 to terminal 42. Again, this will cause conduction through the transistor 54 on a second half cycle relative to the reference voltage, such as is'shown' in the left half of FIGURE 3A-3D. This conduction will energize the relay 161 because the terminal'41 is negative during that half cycle. This energization of therelay 161 reverses the contacts 171 thereof for direct energization of the motor winding 24 and leading current -energization through capacitor 35 of the motor winding 25. This causes clockwise rotation of the motor 12 and rotation of the antenna 36 toward the desired position; Also, the mdtor 12 drives the potentiometer 47 toward rebalance of the bridge.

The turn-on of the transistor 54 also energizes the relay 162 sinceit issupplied wtih a direct current operational' voltage from the directcurrent voltage source developed across the "filter capacitor 71. Energization of relay 162 closes the contacts 172 thereof and, hence, maintains energized the primary circuit of the transformer 13. Accordingly, the knob 88 may be released to close switch 28 and open manualswitclt 20 and again this energization of the relay 162 will take place within about second.

Upon rebalance of the bridge, the voltage output of the bridge will fall to a null to cause the transistor 54 to cease conduction, and, thus, deenergize the

relays

161 and 162. This, of course,de -energizes the entire circuit by opening the relay contacts 172.

I If the knob 88 is moved in a counter-clockwise direc- The operation of FIGURES 2' and 4has been described as stating that Where the potentiometer 46 is rotated clockwise, for 'example,-then the motor 12 also rotates clockwise. 'If the potentiometer 46 is of the type which direction across the point where this potentiometer changes from maximum to minimum impedance and then the motor will rotate in the appropriate direction, which may be the opposite direction in order to effect a rebalance of the bridge circuit. For example, suppose that the potentiometer had the change from maximum to tion, this moves the manual potentiometer 46 in a counterclockwise direction as shown by the arrow 97. This establishes the set of conditions shown inthe. right half of FIGURE 3A to 3D. The phase of the bridge output voltage will then be in phase with the source voltage from terminals 43 to 41. This prevents energization of-relay 161, because blocked by diode 62. This establishes. a

circuit for direct energization of motor winding 25 through relay contacts 171.

Themotor runs counter-clockwise to move the antenna to the desired position and the potentiometer .47 is also driven counter-clockwise to decrease the resistance v.there-.

of toward a rebalance of the bridge. Again, upon bridge rebalance, the transistor 54 ceases conduction .to deenergize relays 162 and 163 to de-energize the entire circuit.

The circuits of FIGURES 2 and 4 are shown as'motor control circuits but it will be observed that they are control systems or apparatus for sensing the phase and, more particularly, a reversal of phase of an alternating current input voltage. The first and

second diodes

62 and 63 together with the alternating current source of the secondary 22.form first and second power supply means of differingphase responsive character and wherein the two power supply means are each conductive only on opposite half cycles of the voltage of the alternating current source. V

The transistor 54 is a form of amplifier having input and output means and more particularly is shown as a semi-conductor amplifier having first, second and third electrodes. This is broadly a type of amplifier in all three circuits which is capable of amplifying two input signals of difiering phase responsive character with first and second load means in the output of the amplifier in separate circuit paths.

Con-currently with the. turn-on .of, the transistor 54, the relay 162 is again energized to close the contacts 172 and maintain the entire circuit energized.

minimum impedance at the South position and no physical stops were provided, then if one rotated the knob clockwise from the SE. to the SW. position through a -degree arc, then this would first decrease and then increase the impedance which would give a signal, upon release of knob 88, so that the motor would rotate in the opposite direction, namely, counter-clockwise, to drive the potentiometer 47 counter-clockwise to decrease the impedance thereof toward a rebalance of the bridge. Accordingly, it will be noted that all the circuits are follow-up motor control systems which tend to establish a rebalance of the bridge regardless of the direction of upsetting influence in the bridge circuit.

The present disclosure includes that contained in the appended claims, as Well as that of the foregoing .de-

scription.

Although this invention has been described in its pre ferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of the circuit and the combination and arrangement of circuit elements may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed. I

What is claimed is:

1. In an antenna rotator device having a motor to rotate an antennato any one of a plurality of places, the

improvement of a switching control system comprising, actuating control means operable to be set at any one of a plurality of positions, means to energize said motor,

relay switching means having first alignment contact; means normally closed to align said motor energizing means in a first condition for rotating said motor in a first direction and having second alignment contact means normally open and disposed to align said motorlenergizQ responsive to movement of said actuating control means in said second direction to provide interruption of said normally closed first alignment contact means and closure zaof said normally open second alignment contact means and thereby change said motor energizing means from 7 said first condition to said second condition, disabling motor switch means having disabling contact means normally closed in series with said relay switching means, and means controlled by said actuating control means to momentarily open said disabling contact means of said motor switch means and thereby momentarily withhold energization of said motor to prevent a false motor start.

' 2. A device as claimed in claim 1 wherein said actuating control means includes lost motion means,

and said means controlled by said actuating control means is controlled by said lost motion means. 3. A'device as claimed in claim 1 wherein said actuating control means includes. lost motion means,

said means controlled by, said actuating control means is controlled by said lost motion means upon initial actuation of said actuating control means to momentarily open said disabling contact means and thereby withhold energization of said motor until after at least one of said first and second conditions of said motor energizing means is established by said alignment contact means,

and means controlled by said lost motion means upon release of said actuating control means to close said disabling contact means to energize said motor.

4. Switch control system for starting and stopping a motor driven load at any one of a plurality of places, said system comprising, actuating control means operable to be set at any one of a plurality of positions, means to energize said motor, bridge circuit means, transformer means to energize said motor circuit means and said bridge circuit means, relay switching means having first alignment contact means normally closed to align said motor energizing means in a first condition for rotating said motor in a first direction and having second alignment contact means normally open and disposed to align said motor energizing meansin a second condition for rotating said motor in a second direction, said bridge circuit means being actuated by said actuating control means and by said motor, movement of said actuating control means in a first direction precluding operation of said relay switching means whereby said first alignment contact means remain normally closed to maintain said motor energizing means in said first condition and reverse movement of said actuating control means caus ing operation of said relay switching means whereby said normally closed first alignment contact means is interrupted and said normally open second alignment contact means is closed to change said motor energizing circuit from said first condition to said second condition, hold-in relay means energized from said bridge circuit means and having hold-in contact means normally open when deenergized, and line switch means responsive to initial movement of said actuating control means in either direction to energize said transformer means which in turn energizes said hold-in relay means to maintain said transformer means energized independent of said line switch means.

5. A system as claimed in claim 4 wherein said rebalancing of said bridge circuit means establishes deenergization of said system,

and said hold-in relay means having means to cause it to dee'nergize quicker than said relay switching means to prevent last minute reversal of said motor as said entire system is being deenergized.

6. A system as claimed in claim 4, including disabling motor switch means having disabling contact means normally closed in series with said alignment contact means of said relay switching means, said disabling motor switch means being responsive to initial movement of said actuating control means in either direction to open said disabling contact means, and release of said actuating control means after movement in either of said directions closing said disabling contact means and energizing said motor, whereby said motor continues to operate until said bridge circuit means is actuated by said motor to establish a balanced condition thereby producing a null electrical condition for de-energizing said hold-in relay means resulting in the deenergization of the entire system and the stopping of said motor.

7. A servo-circuit system having a motor to rotate an element to any one of a plurality of places in a range between first and second rotational limits, the improvement of a switching control system comprising, actuating control means operable to be set at any one of a plurality of positions in a range between first and second limit positions, motor circuit means, relay switching means having first alignment contact means normally closed to establish a first motor circuit for rotating said motor in a first direction toward said first rotational limit and having second alignment contact means normally open and disposed to establish a second motor circuit for rotating said motor in a second direction toward said second rotational limit, first means responsive to movement of said actuating control means in said first direction towards said first limit position to establish a first electrical phase condition to preclude operation of said relay switching means and thereby prevent interruption of said normally closed alignment contact means, second means responsive to movement of said actuating control means in said second direction toward said second limit position to establish a second electrical phase condition for operating said relay switching means and thereby cause interruption of said normally closed first alignment contact means and closure of said normally open second alignment contact means, disabling motor switch means normally closed in series with said alignment contact means, and means to momentarily open said disabling motor switch means and thereby momentarily withhold energization of said motor until after at least one of said first and second motor circuits is established.

8. A motor control circuit for operation from an alternating voltage source comprising in combination, first and second relay means, said second relay means having contact means connected to energize said motor control circuit from the voltage source, said first relay means having double throw contact means connected to control the bi-directional rotation of said motor, actuating control means having first and second conditions, means controlled by said first condition of said actuating control means to energize only said second relay means for energization of said motor control circuit for rotation of said motor in a first direction, means controlled by said second condition of said actuating control means to energize both said first and second relay means to energize said motor control circuit for motor rotation in the opposite direction, disabling switch means normally closed in series with said double throw contact means of said first relay, and means controlled by said actuating control means to momentarily open said disabling switch means and thereby momentarily withhold energization of said motor control circuit.

9. In a motor control circuit to move a load in first and second directions, the improvement of a switching control system comprising, actuating control means operable to be moved in first and second directions, first relay means having first contact means normally closed to establish motor rotation for movement of said load in said first direction and having second contact means normally open to establish upon closing thereof motor rotation for movement of said load in said second direction, first means responsive to movement of said actuating control means in said first direction to preclude interruption of said normally closed first contact means and thereby maintain the direction of load movement in said first direction, second means responsive to movement of said actuating control means in said second direction to provide interruption of said normally closed first contact means and closure of said normally open second contact means and thereby change the direction of load movement to said second direction, second relay means, means to energize said second relay means in response to said first means and to said second means, contacts actuated by said second relay means to energize said motor control circuit and start switch means in parallel with said contact means of said second relay means to energize said motor control circuit.

10. A switching circuit for operation of an electrical load from an alternating voltage source comprising in combination, first relay means having double throw contact means connected to select first and second alternative energization conditions of said electrical load, second relay means having contact means connected to energize said switching circuit from said voltage source, actuating control means operable to be moved in first and second directions, means controlled by said first condition of said l5 a actuating control means to energize only said second relay means for energization .of said switching circuit for energization of said load in said first energization condition, means controlled by said second condition of said actuating control means to energize both said first and second relay means to energize said switching circuit for energization of said load in said second energization condition, disabling switch means normally closed in, series with said load and said double throw contact means, and means controlled by said actuating control means to momentarily open said disabling switch means and thereby momentarily withhold energization of said load.

References Cited by the Examiner UNITED STATES PATENTS 1 2,637,831" 5/1953 Eachus 318289 X 2,863,107 1/1956 Blauvelt 318-207X 3,068,3 8 12/1962 'Burski 318-29 3,126,506 3/1964 Schneider 318-207 3,155,889 11/1964 Stiles et a1. 318- 29 ORIS L. RADER, Primary Examiner. JOHN FL COUCH, Examiner.

B. DOBECK', Assistant Examiner.

Claims

1. IN AN ANTENNA ROTATOR DEVICE HAVING A MOTOR TO ROTATE AN ANTENNA TO ANY ONE OF A PLURALITY OF PLACES, THE IMPROVEMENT OF A SWITCHING CONTROL SYSTEM COMPRISING, ACTUATING CONTROL MEANS OPERABLE TO BE SET AT ANY ONE OF A PLURALITY OF POSITIONS, MEANS TO ENERGIZE SAID MOTOR, RELAY SWITCHING MEANS HAVING FIRST ALIGNMENT CONTACT MEANS NORMALLY CLOSED TO ALIGN SAID MOTOR ENERGIZING MEANS IN A FIRST CONDITION FOR ROTATING SAID MOTOR IN A FIRST DIRECTION AND HAVING SECOND ALIGNMENT CONTACT MEANS NORMALLY OPEN AND DISPOSED TO ALIGN SAID MOTOR ENERGIZING MEANS IN A SECOND CONDITION FOR ROTATING SAID MOTOR IN A SECOND DIRECTION, FIRST MEANS RESPONSIVE TO MOVEMENT OF SAID ACTUATING CONTROL MEANS IN SAID FIRST DIRECTION TO PRECLUDE INTERRUPTION OF SAID NORMALLY CLOSED FIRST ALIGNMENT CONTACT MEANS AND THEREBY MAINTAIN SAID MOTOR ENERGIZING MEANS IN SAID FIRST CONDITION, SECOND MEANS RESPONSIVE TO MOVEMENT OF SAID ACTUATING CONTROL MEANS IN SAID SECOND DIRECTION TO PROVIDE INTERRUPTION OF SAID NORMALLY CLOSED FIRST ALIGNMENT CONTACT MEANS AND CLOSURE OF SAID NORMALLY OPEN SECOND ALIGNMENT CONTACT MEANS AND THEREBY CHANGE SAID MOTOR ENERGIZING MEANS FROM SAID FIRST CONDITION TO SAID SECOND CONDITION, DISABLING MOTOR SWITCH MEANS HAVING DISABLING CONTACT MEANS NORMALLY CLOSED IN SERIES WITH SAID RELAY SWITCHING MEANS, AND MEANS CONTROLLED BY SAID ACTUATING CONTROL MEANS TO MOMENTARILY OPEN SAID DISABLING CONTACT MEANS OF SAID MOTOR SWITCH MEANS AND THEREBY MOMENTARILY WITHHOLD ENERGIZATION OF SAID MOTOR TO PREVENT A FALSE MOTOR START.