US2140387A - Photoelectric relay apparatus - Google Patents

Description

Dec. 413, 1938. P. JUCHTER i PHOTOELECTRIC RELAY APPARATUS Filed March 16, 1935 w Th mm nJ e vv Tm um/'nation 7Zzr/1ad Ufff Illumination 7r/7ed @n Patented Dec. 13, 1938 UNITED STATES PHOTOELECTRIC Pieter J uchter, Scotia,

PATENT OFFICE RELAY APPARATUS N. Y., assignor to General 'l Claims.

My invention relates to photoelectric relay apparatus and particularly to that type of such apparatus which is arranged to operate in one sense when the value of the controlling light, in reducing, passes a certain value and to operate in the opposite sense when the value of the light, upon subsequently increasing again, passes the same or approximately the same value. A common use for such apparatus is that of turning on artiiicial illumination such as street lighting in the late afternoon or evening when daylight has diminished to a predetermined low value and of turning off the illumination in the morning when the returning daylight makes the illumination unnecessary. With such apparatus as it has been constructed heretofore the value of daylight at which the illumination was turned oif in the morning was necessarily somewhat higher than that at which the illumination was turned on in the previous evening. In certain cases, however, it has been found desirable to turn off the illumination in the morning at a materially lower value of daylight than that at which it was turned on in the evening. It is one object of my invention, therefore, to provide photoelectric apparatus which will operate in one sense in response to a predetermined light value when the light is decreasing and will operate in the opposite sense upon a subsequent increase in light when it reaches a second predetermined value which is lower than the first value.

In carrying out the above object of my invention I preferably employ a time controlled device, which for example may be driven by a small electric motor, for effecting the proper change in the apparatus whereby after the illumination has been turned on in the evening in response to the diminishing light it may be turned off in the morning in response to the desired lower value of daylight. If the device is one having a motor which runs continually, such as that commonly employed in electric clocks, there is the possibility that any time lost through an interruption in the energy supplied to the motor or the accumulated time of several interruptions will seriously interfere with the proper operation of the apparatus. Another object of my invention is, therefore, to. provide in such apparatus means whereby such interference with the proper operation of the apparatus may be greatly reduced if not eliminated and a timing error due to. an interruption on one day unless excessive will not carry over to affect the apparatus on the next day.

My invention will be better understood from (Cl. Z50-41.5)

the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is a circuit diagram illustrating one form of my invention; Fig. 2 is a circuit diagram illustrating a further development thereof; Fig. 3 is a diagram illustrating the variations in daylight and the relation thereto of the operation of the apparatus shown by Fig. 2.

In the drawing I have represented at I and 2 an alternating current supply circuit which, for example, may be a 60 cycle, 110 volt, lighting circuit. Arranged to be supplied from this circuit is the artificial illumination circuit 3 to which may be connected electric lamps of any desired form represented, for example, at 4. Circuit 3 is shown controlled by the relay 5 having the energizing winding 6. Connected to be supplied also from the circuit I, 2 is the transformer 8 having the primary 9 and having the tWo secondary windings I0 and II. Secondary winding ID is connected in circuit with the winding ll oi the relay I2 and the electron discharge control device I3 which, for example, may be a Pliotron tube having the anode I4, the cathode I5, and the grid I6, the cathode being connected to be supplied with current from a portion of the winding I0. Relay I2 has the movable contact Il, the fixed front contact IB and the xed back contact I9. When relay I2 is in a deenergized position it completes a circuit from the supply circuit I, 2 through the thermal switch 20, the winding 2I of relay 22 and the resistor 23. I'he thermal device 20 is represented as comprising the heater 24 and the bimetallic switch 25 which is arranged to be heated thereby and which after a predetermined time closes a shunt circuit about the heater. Ihe hand switch 26 is provided to shunt the entire thermal switch if desired. The purpose of thel thermal switch 20 is to prevent the artificial illumination from being turned on in response to temporary decreases in daylight such as might be occasioned by the passing of a cloud or turned off in response to a temporary increase in light such as that due to a flash of lightning.

Relay 22 has the movable contact 28 arranged to engage the iixed front contact 29 for the purpose of closing a holding circuit for the winding 2l thereof. This relay also has the movable contact 3E! arranged to engage the fixed front contact 3| for closing the circuit of the winding 6 of the relay 5, which circuit is connected to receive energy from the supply circuit I, 2. It will be seen from the drawing that when relay I2 is in its energized position, as illustrated, contacts I'I and I8 close a short circuit through the timing switch 2B around the winding 2| of relay 22 which relay remains open as illustrated.

Referring now to. the control circuit for the control device I3, both ends of the secondary winding II are connected with the grid I5 of this device, the one end being connected therewith through the photo-electric device 34, which is so arranged that it is not affected by the artificial illumination, and the other end being connected therewith through the small capacitor 36 and resistor 37. Connected with the ends of winding II are the potentiometer 38 having the movable arm 39 and the potentiometer 40 having the movable arm 4I. Arm 39 connects through the resistor 42 with the cathode I5 of device I3. Arm 4I connects directly with the cathode I5 through the time switch 43. The latter switch is operated by a timing device, preferably an electric clock, and in the drawing is represented as being actuated by the cam 44 which is driven by the small synchronous motor 45 supplied from the circuit I, 2. Cam 44 is arranged to make one revolution per day and as shown has the high portion 45 adapted to hold the switch open and the low portion 41 adapted to allow the switch to close.

The position of the various parts of the apparatus may, for example, be that which would obtain in the afternoon when the value of daylight is such that artificial illumination is not required. At this time the value of daylight reaching the photo device 34 and the setting of the potentiometer arm 39 are such that the relay I2 is held energized by the current passing the discharge device I 3, relay 22 is short-circuted and therefore deenergized, and relay 5 also is deenergized, hence the illumination circuit 3 is open. As the value of daylight decreases in the late afternoon or early evening, the potential of the grid I6 becomes more negative or less positive relative to the cathode, as the case may be, and at a predetermined value of daylight at which it is desired to have artificial illumination turned on the relay I2 becomes deenergized sufficiently to allow Contact I'I to shift from contact I8 to contact I9 thus closing the circuit of relay 22 through the thermal switch 2H. As soon as the latter switch operates, relay 22 is energized, locking itself in closed position and closing the circuit of relay 5, thereby turning on the articial illumination.

At sometime later in the evening, such for example at midnight, when the amount of daylight reaching the photo device 34 has reduced to a very low value, the cam 44 will have been rotated to such a position that the switch 43 will drop off the high portion of the cam and close. By this operation of the time switch the cathode I5 is put into direct control of the potentiometer 49 which will be so set that the grid will be rendered more positive relative to the cathode for the same degree of daylight. It will be noted that with the apparatus disclosed the cathode potential is changed by the time switch rather than the grid potential but the effect is the same and that the connection between the cathode and potentiometer 40 does not include a resistor such as that in connection to potentiometer 38. Thus the former potentiometer will take over the control of the device I3.

With potentiometer 4B now in control of device I3 and being set to cause the energization of device I3 and therefore of relay I2 in response to a lower value of daylight than that at which relay I2 was previously deenergized, it will be seen that the artificial illumination will be turned off in the morning at a value of daylight which is lower than that at which the lights were turned on in the previous afternoon or evening. The cam 44 continues to rotate, and at a time which may be several hours after the artificial illumination has been shut off in the morning, for example, about noon time, the switch 43 will ride up on the high portion of the cam and interrupt the connection between the cathode and the potentiometer 40. Thus control of the device I3 by potentiometer 38 will be restored and the cycle of operation of the apparatus will be completed.

With apparatus such as I have described above' which employs a timing switch driven by a motor which runs continually there is the possibility that as a result of an interruption, say of several hours, in the supply of energy, or of a series of interruptions which may occur on succeeding days, the total time lost may seriously interfere with the proper operation of the apparatus. To avoid this difficulty I have provided in the further developed form shown by Fig. 2 means whereby the motor driving the time switch runs for only a portion of the time through each day, the motor being automatically started and stopped whereby any time lost through an interruption of the service unless it is of very long duration will not ordinarily cause an error in the operation of the apparatus to carry over from one day to the next. The apparatus disclosed by Fig. 2 for the most part is like that shown in Fig. l. In this form, however, the time switch 43' is provided with two additional moving contacts 59 and 5!, the former being arranged to engage the fixed contacts 52 when the switch drops off from the high portion of the cam and the latter being arranged to disengage the fixed contacts 53 at the same time. Relay 22 is provided with a back contact 55 for the moving contact 30 thereof. 'I'his contact 55 connects with the contacts 52 of the time switch, and the middle contact 3| connects with the fixed contacts 53 of the time switch.

With the apparatus in the position shown by Fig. 2 which, for example, may be in the afternoon, the circuit of the motor 45 will be closed by contacts 5I, 53 but will be open at contacts r 30 and 3I of relay 22. The clock therefore is not running at this time and potentiometer 38 is controlling device I3. As the value of daylight decreases to a predetermined point in the late afternoon or early evening the photo device causes the deenergization of relay I2 and the energization of relays 22 and 5 to turn on the artificial illumination as described above in connection with Fig. 1. The point at which the illumination is turned on may, for example, be that indicated by the point A on the curve 6D which may be assumed to represent roughly the amount of daylight at various hours throughout the day. The point A is represented in the diagram, for eX- ample, as occurring at 7 P. M. By reason of the connection between contact 3I of relay 22 and the motor 45 through contacts 5I and 53 the energization of relay 22 will cause the clock to start. The speed at which the cam 44 rotates in this form of my invention is considerably faster than that at which the cam 44 rotated in the form shown by Fig. l. As a result of this greater speed of the cam, switch 43 will drop off of the high portion of the cam a few hours later, for example, at midnight when the value of daylight is reduced to a value which is lower than that at which it is desired to have the illumination turned on in the following morning. The switch 43 in dropping off the high portion of the cam will open the circuit of the clock motor at 5i, 53 and thus cause the clock to stop and will transfer control of device. i3 to potentiometer liti. On the following morning when daylight increases to a value at which it is desired to have the illumination turned cf, which value is represented on the diagram as point B occurring at fi A. M., the several relays will be operated in a manner described in connection with Fig. l to open the artificial illumination circuit 3. It will be noted that point B is considerably lower than` point A. By the deenergization of relay 22 the circuit of the clock motor is again established through the relay contacts 3B and 5.5, it being remembered that contacts 5U and 52 of the time switch were closed when the switch t3 dropped cil the high portion of the cam. The clock now ,st/arts again and runs until the switch 43 ridesrup on the high portion of the cam which opens the clock motor circuit at th-e contacts 5i), 52 and which restores control of device I3 to potentiometer 38. This stopping of the clock may occur at any time after daylight has reached a value higher than that represented by the point A at which the lights were turned on. In the diagram it is shown occurring at about noon. The clock then remains inactive and the switch 4 also remains in a position, to leave potentiometer 38 in control of device I3 until such time in the afternoon at which it is desired to have the illumination turned on.

While li have shown` and described the clock as coming to a stop at midnight and again at noon, it will be understood that the actual time of running of the clock may, if desired, be made considerably shorter, for example, by increasing the speed at which the cam is driven whereby interruptions that may occur in the service may be less likely to come during those periods in which the clock is running. Thus the clock may be constructed to stop at l p. m. and again at 8 a. m. the only requisite being that the stop at night must occur after such a time at which the corresponding value of daylight is somewhat less than that of B; likewise the stop in the day time must occur after such a time at which the corresponding value of daylight is somewhat greater than that of point A.

While I stated in the introductory portion of this description that a common use of the apparatus is for turning on and oiT artificial illumination such as street lighting, it may have various other uses as well, such as the control of electric signs. As such signs usually are turned off long before the approach of daylight, the arm 4I of potentiometer #tu of the present apparatus would be set so far to the left that when switch 43 closes say at midnight device I3 would be operated to cause the lamps 4 of the sign to be extinguished.

I have chosen the particular embodiments described above as illustrative of my invention and it will be apparent that various other modications may be made without departing from the spirit and scope of my invention which modifications I aim to cover by the appended claims.

What I claim as new and desire to secure by etters Patent of the United States, is:

1. Photoelectric relay apparatus including a photoelectric device adapted to be subjected to the varying intensity of daylight, said apparatus being constructed to operate in one sense in respense to a predetermined light value when the light is diminishing, means for causing the apparatus to operate in the opposite sense in response to a lower predetermined light value when the light subsequently increases and time controlled means for rendering said means inoperative until a time corresponding to a daylight intensity that is less than said lower predetermined value, means for rendering said time controlled means inoperative at said time and means for rendering it again operative when the light subsequently attains said lower predetermined light value.

2. Photoeiectric relay apparatus including a photoelectric device adapted to be subjected to the varying intensity of daylight, said apparatus being constructed to operate in one sense in response to a predetermined light value when the light is diminishing, means for causing the apparatus to operate in the opposite sense in response to a lower predetermined light value when the light subsequently increases, a motor controlled switch for rendering said means inoperative until a time corresponding to a daylight intensity that is less than said lower predetermined value, means for rendering said motor inoperative at said time and for rendering it again operative when the' light subsequently attains said lower predetermined value.

3. Photoelectric relay apparatus for controlling a lighting circuit comprising a photoelectric device adapted to be aiTected by daylight, said apparatus being constructed to close said circuit when daylight decreases to a predetermined value, means for causing said apparatus to open said circuit when daylight in subsequently increasing reaches a low predetermined value, a motor driven switch for rendering said means incapable of functioning until such a time at which daylight should have decreased to a value below said lower predetermined value, means operative to deenergize the motor at said time and means operative to re-energize the motor when said lighting circuit is opened.

4. Photoelectric relay apparatus including a phctoelectric device adapted to be subjected to the varying intensity of daylight, said apparatus being constructed to operate in one sense in response to a predetermined light value when the light is increasing, means for causing the apparatus to operate in the opposite sense in response to a higher predetermined light value when the light subsequently decreases and time controlled means for rendering said means inoperative until a time corresponding to a daylight intensity that is greater than said higher predetermined value, means for rendering said time controlled means inoperative at said time and means for rendering it again operative when the light subsequently attains said higher predetermined light value.

5. Photoelectric relay apparatus including a photoelectric device adapted to be subjected to the varying intensity of daylight, said apparatus being constructed to operate in one sense in response to a predetermined light value when the light is increasing, means for causing the apparatus to operate in the opposite sense in response to a higher predetermined light value when the light subsequently decreases, a motor controlled switch for rendering said means inoperative until a time corresponding to a daylight intensity that is greater than said higher predetermined value, means for rendering said motor inoperative at said time and for rendering it again operative when the light subsequently attains said higher predetermined value.

6. Photoelectrie relay apparatus for controlling a lighting circuit comprising a photoelectric device adapted to be affected by daylight, said apparatus being constructed to close said circuit when daylight increases to a predetermined value, means for causing said apparatus to close said circuit when daylight in subsequently decreasing reaches a higher predetermined value, a motor driven switch for rendering said means incapable of functioning until such a time at which daylight should have increased to a value above said lower predetermined value, means operative to deenergize the motor at said time and means operative to reenergize the motor when said lighting circuit is closed.

7. Photoelectrc relay apparatus for controlling a lighting circuit comprising a photoelectric device arranged to be affected by daylight, said apparatus being constructed to close said circuit when daylight decreases to a predetermined value, means for causing said apparatus to open said circuit when daylight in subsequently increasing reaches a lower predetermined value and means comprising a synchronous motor and a switch operated thereby for rendering said means incapable of functioning until such a time at which daylight should have decreased to a value below said lower predetermined value, means operative to open the circuit of said motor at said time and means operative to close the motor circuit when the lighting circuit is opened.

PIETER JUCHTER.

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