DE2234002A1 - RELAY SWITCHING - Google Patents

Description

Patent attorneys Dipl.-Ing. W. Scherrmann Dr.-Ing. R. Ruger

73 Esslingen (Neckar), Fabrikstrasse 9, PO Box 348

July 10, 1972 _{Tele (on}

PA 4 "5 rünae. Stuttgart {0711) 254539

35 * 419

Telegrams patent protection Essllngenneckar

Eaton Corporation, 100 Alder View Plaza ,; Cleveland, Ohio 44ll4

US A ■

Relay circuit

The invention relates to a relay circuit with a Emit switching signals for actuating a relay Signal source.

Computer controls of machines and devices are being used to an increasing extent. There is one here However, there is a limitation that often parts of the logical Computer circuits necessary to operate relays Can't stand tensions. This means that relays can be actuated directly such logic circuits were not possible. Since logical In addition, circuits "are usually based on digital technology, so they are usually very sensitive against temporarily occurring interference voltages, such as noise, such interference voltages often as signals be misunderstood, which triggers an unintended switching. Numerous attempts have been made to this To remedy difficulties. However, none of these attempts led to completely satisfactory results. Many known devices of this type are complex, expensive and space-consuming. Other such well-known Devices try to reduce the noise or to improve the signal / ratio ratio " and not to separate the logic circuits from the actual relay circuit. Still other circuits

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use capacitors to isolate the logic circuits. These However, facilities tend to breakdown when high interference voltages occur, so that they just then fail when they are needed.

The invention is therefore based on the object of a To create relay circuit of the type mentioned at the beginning, which allows an exact and reliable relay control through logic circuits and the like, while at the same time the logic circuits also protect against very strong transient interference voltages are protected.

To solve this problem, the relay circuit according to the invention is characterized in that with the signal source a Potokouplungseinheit receiving switching signals is connected, through which the received signals transmitted optically and in electrical characteristic of the switching signals emitted by the signal source Output signals are convertible and that a triac (two-direction thyristor triode) is connected in series with the relay which blocks the flow of current through the relay in the normal high-impedance state and in the low-impedance state enabled and assigned to the switching means, depending on the received from the Potokouplungseinheit electrical signals transform the triac from the high impedance state to the low impedance state.

The new relay circuit prevents any feedback from the relay to the logic circuits; it thus prevents noise from the relay from entering the logic circuit. Besides, the new relay circuit compact, robust, simple, maintenance-free and relatively cheap.

209885/1313

In the drawing, an embodiment of the subject is shown. The figure shows a Relay circuit according to the invention in schema.tischer Depiction.

In the embodiment chosen to explain the invention, as shown in the figure, • A transistor 2 is provided, its collector / neutral circuit Via the photodiode 6 in series of a photocoupling unit 8 to a suitable voltage source 4 connected. The base of the transistor 2 are controlled by a logic circuit or the like generally indicated at 5, fed switching signals supplied, made conductive by the transistor 2 is, so that current can flow through the photodiode 6, whereby this is stimulated to emit light. The photocoupling unit 8 also has a photocell 10 or the like, which in the absence of light Radiation has a high impedance - but has a relatively low impedance when exposed to light. The photocell 10 is in series with a capacitor 14 and a suitable load relay 12. In addition, a Triac l6 connected in parallel to the photocell 10 and the capacitor, while a Zener diode l8 is provided to the Rfcential between the photocell 10 and the capacitor 14 to be sampled and ^ if this signal is the value of the Zener breakdown range exceeds the control electrode of the triac 16 to feed a signal. In parallel with the triac 16 are a resistor 20 and a capacitor 22 which have the task of accidental ignition of the triac ΐβ to prevent rapid electrical phenomena or the like Build-up of stress. In a similar way a resistor 24, a capacitor 26 and a thyrrector 28 form a discharge circuit for temporary occurring high voltage.

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In operation, signals from a logic circuit 3 or the like fed to the base of transistor 2,

whereby the transistor 2 in the conductive state over / becomes

guided whereby current can flow through the photodiode β. This has the consequence that the photodiode 6 emits light which is received by the photocell 10, which in turn As a result, the photocell 10 allows current to flow to the capacitor 14, which begins to charge. When the capacitor 14 is charged, the potential applied to it reaches the Zener breakdown voltage, so that the Zener diode l8 is conductive and the control electrode of the triac l6 feeds a signal. The triac l6 has a very high impedance before ignition. Upon ignition, the impedance drops to a very low one Value at which it remains until the current flowing through the triac ΐβ falls below the corresponding lower The limit value drops, whereupon the triac l6 returns to the high impedance state. The by the in the state The triac 16 located at a low impedance is used to actuate the relay 12.

As indicated above, the photocell 10 is physically and electrically isolated from the photodiode 6. Accordingly, it is impossible for transient noise voltages to pass through the photocoupling unit 8 regardless of their size. In addition, no signals of any kind that pass through the photocell 10 have an influence on the photodiode 6. Accordingly, no feedback signals can pass through the photocoupling unit 8. This means that the logic circuits j5 are completely isolated from the relay Ί2 , although their control influence on the relay is fully preserved.

A number of modifications and configurations are possible within the scope of the invention. The exemplary embodiment described therefore does not represent a restriction of the inventive concept.

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Claims (1)

fa. t en ta ns ρ r ü G h. e 1. Relay circuit with ein'r switching signals for actuating a relay emitting signal source, characterized in that. with the signal source (j5) a switching * - signals receiving photocoupling unit (8) is connected, through which the received signals are transmitted optically and converted into electrical output signals characteristic of the switching signals emitted by the signal source (J>) and that in Series to the relay (12) a triac. (16) (two-directional thyristor triode) is connected, which blocks the flow of current through the relay (12) in the normal high impedance state and in the low impedance state enables and the switching means (] A , l8) which, depending on the electrical signals received by the photocoupling unit (8), transfer the triac (l6) from the high impedance state to the low impedance state. 2. Circuit according to claim 1, characterized in that the photocoupling unit (8) photo-emitting means (6), which are current-permeable as a function of switching signals coming from the signal source and in Emit light depending on the current flowing through it and that also the photocoupling unit (8) has photosensitive means (10) which the received light emitted by the photo-emitting means (9) and depending on the received light emit an electrical signal. >. Circuit according to Claim 2, characterized in that that the photosensitive means (10) physically and electrically from the photo-emitting means (6) are isolated. 209885/1313 4. A circuit according to claim 2, characterized in that the photosensitive means is a photocell (ΙΟ) are. 5. A circuit according to claim 2, characterized in that the photo-emitting means is a photodiode (6) are. 6. A circuit according to claim 2, characterized in that the signal source has a transistor (2), whose collector-emitter circuit is in series with the photo-emitting means (6) and whose base Signals from a Singangssignalquelle (j5) can be fed. 7. Circuit according to claim 6, characterized in that that the input signal source is a logic circuit (3). 8. A circuit according to claim 1, characterized in that the switching means has one, the electrical signals from the photocoupling unit (8) receiving and depending on these electrical signals a charge-absorbing capacitance (I ¹ O and a Zener diode (l8), which the charge of the capacitance (l4) is sampled and a signal is supplied to the control electrode of the triac (l6) as a function of values of this charge which exceed a predetermined value. 20 98 85/13 13