GB2163303A

GB2163303A - Socket including voltage peak clipping filter

Info

Publication number: GB2163303A
Application number: GB08420703A
Authority: GB
Inventors: Ming Tang Huang
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-08-15
Filing date: 1984-08-15
Publication date: 1986-02-19
Also published as: GB8420703D0

Abstract

An socket for electronic equipment comprises a switch with an indication lamp (not shown), a trip free relay 22 connected to the switch 21 for opening the socket circuit when an overload or a short- circuit condition occurs, a filter 25 coupled with the trip free relay 22 for attenuating radio noises and electromagnetic waves, a clipping circuit 26 including metal oxide varistors coupled to the filter 25 so as to suppress suddenly rising voltage pulses, and at least one socket component 24. <IMAGE>

Description

SPECIFICATION An improved socket for electronic equipment The present invention reiates to an improved socket for electronic equipment, and particularly to a socket capable of suppressing any sudden power surge which may cause harm to electronic equipment; eliminating interference from noise signals; and automatically disconnecting with an electric power source when an overload or a short-circuit condition occures.

Since the rapid development of applied science, many advanced electronic devices are now in common use in commerce, industry, school, and the home. For example, the computer for data base management and word processing is commonly used for commercial applications, the computer can also be used for controlling automatic production procedures in industrial applications. Also, the personal computer is being gradually accepted for storage and information management by the family for daily usage.

Certain components of electronic equipment, such as the IC chip, are susceptible to conditions which may cause serious damage, for example: 1. A sudden alteration of source voltage: this may occur under the following circumstances: (a) interruption of electric power: If the computer does not have auxiliary power, the data stored in random acess memory (RAM) will disappear when the electric power is terminated.

(b) insufficient voltage: When an increase in the power load occurs, causing an increase in current, then this action causes the voltage to decrease. When the voltage drops below an accepted range, the electric device may not function properly.

(c) voltage pulse: A voltage pulse may occur under three different situations: (1) when the voltage suddenly rises, (2) when the voltage suddenly drops, or (3) when an instantaneous high-voltage impulse occurs. For example, the action of turning on/off an electric device will cause an instantaneous impulse to be transmitted through the electric line, so that it may harm other electronic equipment which is energized by the same electronic power.

(d) noise signals: Since noise signals having a frequency between 10 KHZ and 50 MHZ can freely transmit in the air and/or along an electric power line, it, therefore, may interfere with the operation of electronic equipment.

2. radio-frequency interference and electromagnetic interference, that may affect the screen of a computer display device and/or the sensitivity of the computer components.

3. An overload or short-circuit condition: The overload or short-circuit condition generates an overcurrent which may destroy susceptible elements of an electronic device.

In view of the aforesaid, the normal electric power transmitted from the local power station is not really a reliable source of power for certain electronic equipment. However, the typically used socket is directly connected to the normal electric power source. Thus, if the source voltage sent from the socket suddenly changes, the data stored in the RAM may be disappear forever, and the computer may also be damaged.

It is an object of the present invention to provide an improved socket for electronic equipment which includes a clipping circuit for suppressing any sudden power surge which may cause harm to any susceptible circuit of electronic equipment.

It is another object of the present invention to provide an improved socket for electronic equipment which includes means for filtering radio noises and electromagnetic waves transmitted in an electric power line.

It is yet another object of the present invention to provide an improved socket for electronic equipment which includes a trip free relay for automatically disconnecting with the electric power so as to protect the electronic equipment from an overload or a short-circuit condition.

it is yet another object of the present invention to provide an imprived socket for electronic equipment which has a switch with a lamp bulb disposed therein for switching on/off the electric power to determine whether or not the socket is energized. When the switch is on, then the lamp bulb is lit for indication that the socket is energized.

The present invention will be more fully understood from the following detailed description, taken in connection with the accompanying drawings which form a part of this application, and in which: Figure 1 is a structural plan view of an improved socket according to a preferred embodiment of the present invention.

Figure 2 is a block diagram of the present invention.

Figure 3 is a schematic electrical diagram of an improved socket according to a preferred embodiment of the present invention.

In Fig. 1, there is shown an improved socket 50 for electronic equipment according to the present invention, which comprises a plurality of socket components 24's, a switch 21, a filter and clipper circuit 10, a trip free relay 22, and an electric power line 1 5. These elements and their relationships will be described in detail hereinafter.

Referring to Fig. 2 and 3, the switch 21 is connected to an electrical power source 20 through the electric power line 15, as shown in Fig. 1, for turning on/off the improved socket 50. A lamp bulb (not shown) is disposed in the switch 21 for giving a visual indication that the improved socket 50 is energized. The trip free relay 22, which is capable of opening the improved socket circuit for protection of electronic equipment upon an overload or a short-circuit condition, is connected to the switch 21.

A means 25 for filtering noise signals transmitted in a power line is coupled to the trip free relay 22 so as to attenuate radio noises and electromagnetic waves existing in the electric power line 1 5. A preferred embodiment of the filtering means 25 is a it-type filter which consists of three capacitors C1, C2, and C3, and two inductors L1 and L2, as shown in Fig. 3. A clipping circuit 26 is coupled to the filtering means 25 for clipping voltage peaks of either polarity when they exceed a predetermined amplitude. Any person ordinary skilled in the art should understand that an overvoltage crowbar protection circuit also can be employed.However, when the period of a voltage pulse is shorter than 100 it s, the crowbar protection circuit can not function because its elements of SCR and Triac have a lower response speed. Thus, in the preferred embodiment of the present invention, the clipping circuit 26 shown in Fig.

3 is used.

The clipping circuit 26 comprises two mental-oxide varistors (MOV) MOV1 and MOV2, one of the terminals of each mental-oxide varistors MOV1 and MOV2 are grounded, and the other terminals of each mental-oxide varistors MOV1 and MOV2 are connected to two output terminals of the filtering means 25 respectively, as shown in Fig. 3. The MOV is a non-linear component, which has an impedance characteristic dependent on the variations of current and voltage, and is similar in characteristics to that of a backforward-biased zener diode. If the voltage of the filtered input signal from the filtering means 25 is less than a predetermined conduction voltage of MOV, the clipping circuit 26 acts as an open circuit.

Thus, the filtered input signal is transmitted unchanged to the socket component 24. On the other hand, if the voltage of the filtered input signal from the filtering means 25 is greater than the predetermined conduction voltage, the clipping circuit 26 conducts and acts as a short circuit connecting to the socket component 24. Thus, the filtered input signals are clipped to a safe voltage levels, and the function of suppressing any sudden power surge is achieved.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims which scope is to be accorded the broadest interpretation so as to encompass all such modification and equivalent structures.

Claims

1. An improved socket for electronic equipment comprising at least one socket component adapted to receive an electric power source, and a clipping circuit connected in parallel with said socket component for clipping voltage peaks of either polarity, when they exceed a predetermined amplitude, thereby preventing electronic equipment from being damaged by any suddenly rising voltage pulse.

2. An improved socket for electronic equipment according to claim 1, further comprising means for filtering noise signals transmitted in an electric power line, coupled with said clipping circuit so as to attenuate radio noises and electromagnetic waves existing in said electric power line.

3. An improved socket for electronic equipment according to claim 2, wherein said filtering means is a 7r-type filter.

4. An improved socket for electronic equipment according to claim 1, 2, or 3, further comprising a trip free relay to which said filter is coupled, being capable of automatically disconnecting with said electric power source for protection of said electronic equipment when an overload or a short-circuit condition occures.

5. An improved socket for electronic equipment according to claim 1, 2, 3, or 4, wherein said clipping circuit includes two mental-oxide varistors, one of the terminals of each mental-oxide varistors are grounded, and the other terminals of each mental-oxide varistors are connected to two output terminals of said filtering means respectively.

6. An improved socket for electronic equipment according to claim 1, 2, 3, 4 or 5, further comprising a switch connected to said electric power line for switching on/off the connection with said electric power source.

7. An improved socket for electronic equipment according to claim 6, wherein said switch includes a lamp bulb disposed therein for giving a visual indication that said improved socket is energized.

8. An improved socket for electronic equipment substantially as hereinbefore described with reference to the accompanying drawings.