GB2062242A - Contactless electronic switching device - Google Patents
Contactless electronic switching device Download PDFInfo
- Publication number
- GB2062242A GB2062242A GB8031207A GB8031207A GB2062242A GB 2062242 A GB2062242 A GB 2062242A GB 8031207 A GB8031207 A GB 8031207A GB 8031207 A GB8031207 A GB 8031207A GB 2062242 A GB2062242 A GB 2062242A
- Authority
- GB
- United Kingdom
- Prior art keywords
- oscillator
- switching device
- electrical
- coil
- electronic switching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 22
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000005030 aluminium foil Substances 0.000 claims abstract description 7
- 239000011889 copper foil Substances 0.000 claims abstract description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000006229 carbon black Substances 0.000 claims abstract description 4
- 239000004020 conductor Substances 0.000 claims abstract description 4
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 4
- 239000010439 graphite Substances 0.000 claims abstract description 4
- -1 e.g. Substances 0.000 abstract description 2
- 238000012216 screening Methods 0.000 description 8
- 238000010276 construction Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000013016 damping Methods 0.000 description 5
- 230000005684 electric field Effects 0.000 description 5
- 230000001965 increasing effect Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 230000005672 electromagnetic field Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 230000002452 interceptive effect Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 108010014172 Factor V Proteins 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
- G01V3/101—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/945—Proximity switches
- H03K17/95—Proximity switches using a magnetic detector
- H03K17/9505—Constructional details
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Remote Sensing (AREA)
- Geology (AREA)
- Environmental & Geological Engineering (AREA)
- Electromagnetism (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
- Electronic Switches (AREA)
- Switches That Are Operated By Magnetic Or Electric Fields (AREA)
Abstract
A contactless electronic switching device consisting of on oscillator (1) susceptible to external influence, an electronic switch (3) controllable by the oscillator, has the coil (5) of the oscillator electrically screened on all sides, so as to suppress interference surges. When the oscillator coil (5) is located in a ferrite pot (6) open on one side, the open side of the ferrite pot is provided with an "electrical" screen (7), which may consist of laminar distribution of electrically conducting material, e.g., carbon black and/or graphite, or it may consist of a very thin aluminium or copper foil, the "electrical" screen preferably being conductively connected to the ferrite pot. <IMAGE>
Description
SPECIFICATION
Contactless electronic switching device
This invention relates to a contactless electronic switching device, consisting of an oscillator susceptible to external influence, of an electronic switch, e.g., a transistor, a thyristor or a
Triac, controllable by the oscillator, possibly via a switching amplifier or the like, and, in certain cases, of a supply circuit for the production of the supply voltage for the oscillator and possibly for the switching amplifier, in which the oscillator possesses a coil and the coil is preferably located in a ferrite pot open at one side.
Electronic switching devices of the abovedescribed kind are used to an increasing extent in electronic measurement, control and regulation circuits in place of mechanically operated electrical switching devices. In respect of effect on the oscillator a differentiation must be made between inductive and capacitative effects.
In contactless electronic switching devices of the above-described kind, subjected inductive influence on the oscillator, the condition K.V= 1, where K is the feedback factor and V is the amplification factor, applies to the oscillator so long as a metal object has not yet come within a specified distance, i.e. the oscillator oscillates.
When the metal object in question reaches the specified distance, increasing damping of the oscillator leads to a reduction of the amplification factor V, so that K.V becomes less than unity, i.e.
the oscillator ceases to oscillate.
In contactless electronic switching devices of the above-described kind, subjected to capacitative influence of the oscillator, the condition K.V < 1 applies to the oscillator, i.e. the oscillator does not oscillate so long as a response body has not yet sufficiently increased the capacity between a response electrode and a counter-electrode. When the response body reaches the specified distance, the increasing capacity between the response body reaches the specified distance, the increasing capacity between the response electrode and the counterelectrode leads to an increase of the feedback factor K, so that K.V becomes unity, i.e. the oscillator starts to oscillate. In both forms of construction the electronic switch, e.g. a transistor, thyristor or Triac, is operated, irrespective of the differing oscillator conditions.
Contactless electronic switching devices were originally subject to a series of difficulties when compared with electrical, mechanically operated switching devices, these including problems such as "Production of a power supply for the oscillator and if necessary for the switching amplifier", "Construction of the oscillator", "Suppression of switching surges", "Shortcircut stability". German
Offenlegungeschriften, Auslegeschriften and
Patents 1951137
1966178
1966213 2036840 21 27 956
22 03 038
22 03 039 2203040 22 03 906
22 30 233 2231732
2356490
2613423
2616265
2616773 26 28 427
27 11 877 are amongst those concerned with these problems (and with other problems relevant to contactless electronic switching devices) and their solutions.
A further problem is relevant to contactless electronic switching devices of the abovedescribed kind, and particularly to those in which the oscillator is inductively influenced, which may be described as "interference surge suppression".
Here "interference surge" is to be understood as a, generally momentary, switching on of the electronic switch of the switching device in question, brought about by external influences other than the intended functional influence. Such interference surges particularly occur when the parts of the electronic switching device that are sensitve in this respect (the oscillator coil, other oscillator components or other circuit components of the switching device) are affected by interfering electrical field variations.In this connection it is not necessary that these electrical field variations should occur or be present near to the switching device in question itself; interfering electrical field variations can in addition be caused in the following manner:
Electronic switching devices of the type in question are connected to the supply mains by generally two or three external leads, and here the supply mains themselves are connected conductively or capacitatively - to earth potential, and thus are tied down, more or less firmly, to earth potential, whilst the electronic switching devices in question are "in the air" at the ends of external leads remote from the mains.
If now a voltage surge is induced in the external leads between the supply mains and the electronic switching device in question, e.g. by currentcarrying electrical wires or cables being laid in the vicinity of the external leads of the electronic switching device in question, the potention of the device as a whole "oscillates" relatively to earth potential. This has the same effect, relatively to earth potential, as field variations that influence the electronic switching device.
In order to suppress the above-explained interference surges, "screening" must be provided. In this respect it is known on the one hand to earth the ferrite pot associated with the oscillator coil (or a ferrite core, if this should be the only ferrite part present) and on the other hand to screen the "sensitive parts" of the electronic switching device of the type in question -- with the exception of the oscillator coil. (In the following it will always be assumed that the oscillator coil of the electronic switching device in question is located in a ferrite pot open at one side.The considerations that arise from this can however also be applied to forms of construction of the above-described electronic switching device in which the oscillator coil is not located in a ferrite pot.)
The oscillator coil, located in a ferrite pot open at one side, of the electronic switching device in question is, so to speak, a "receiver" for electrical field variations (and also for electromagnetic field variations which however do not occur to any extent). It would appear here that screening is impossible because the electromagnetic alternating field of the oscillator coil of the electronic switching device in question must for its operation emerge from the ferrite pot, so that the coil can be damped by the production of eddy currents in an approaching metal object.
The object of the invention is to provide a contactless electronic switching device in which interference surges are suppressed more effectively than they are according to the present state of the art.
It has been stated above that (complete) screening of the oscillator coil of the electronic switching device in question does not appear to be possible because the electromagnetic alternating field of the coil must for its operation be able to penetrate outwards so that the coil can be damped. If a distinction is now drawn between "electrical" screening on one hand and "electromagnetic" screening on the other, it becomes clear that "electrical" screening of the oscillator coil screens off the above-explained electrical field variations without the electromagnetic field variations of the coil being screened.
Consequently, according to the present invention, a contactless electronic switching device consists of an oscillator susceptible to external influence, and an electronic switch controllable by the oscillator, which possesses a coil that is electrically screened on all sides. In the form of construction of the electronic switching device according to the invention in which the oscillator coil is located in a ferrite pot open on one side this means that "electrical" screening is provided on the open side of the ferrite pot.
If account is taken of the fact that in the contactless electronic switching device according to the invention the oscillator coil must be capable of being damped by an approaching metal object, it follows from this that in "electrical" screening of the oscillator coil the "electrical" screen on the one hand must not form an electrically conducting surface, so that the "electrical" screen either results in no damping of the oscillator coil at all, or such damping as may exist allows of adequate additional damping by an approaching metal object, and that on the other hand the "electrical" damping must not contain any ferromagnetic material. Consequently the "electrical" screen preferably consists of a laminar distribution of electrically conducting material, e.g., carbon black of graphite.The "electrical" screen can however also consist of a very thin aluminium or copper foil. (Although an aluminium or copper foil naturally represents an "electrically conducting surface", an extremely thin -- "gossamer thin" aluminium or copper foil can be employed as an "electrical" screen because eddy currents are not formed, or are not formed to any practical extent, in a "gossamer thin" aluminium or copper foil.)
Finally it is desirable that the "electrical" screen should be conductively connected to the ferrite pot, so that the "electrical" screen is earthed via the ferrite pot.
A preferred form of construction of contactless electronic switching device according to the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawing.
The contactless electronic switching device represented in the drawing consists in essential electrical construction of an oscillator 1 that is susceptible to external influence -- by a metal object that is not shown - of a switching amplifier 2 that is merely indicated, of an electronic switch 3, e.g. a transistor, a thyristor or a Triac, capable of operation by the oscillator 1 via the switching amplifier 2, and of a power supply circuit 4, merely indicated, to produce the supply voltage for the oscillator 1 and the switching amplifier 2. The oscillator 1 possesses a coil 5, which is located in a ferrite pot 6 open on one side.
According to the invention, the coil 5 of the oscillator 1 is "electrically" screened on all sides.
The coil 5 of the oscillator 1 is located in a ferrite pot 6 open on one side and an "electrical" screen 7 is provided on the open side of the ferrite pot 6.
The "electrical" screen 7 consists of a laminar distribution of electrically conducting material, e.g.
of carbon black and/or graphite. (The "electrical" screen can also consist of an exceedingly thin aluminium or copper foil.) The "electrical" screen 7 is conductively connected to the ferrite pot 6.
Claims (6)
1. A contactless electronic switching device consisting of an oscillator susceptible to external influence, and an electronic switch controllable by the oscillator, which possesses a coil that is electrically screened on all sides.
2. A switching device according to Claim 1, in which the oscillator coil is located in a ferrite pot open on one side, and wherein the open side of the ferrite pot is provided with an "electrical" screen.
3. A switching device according to Claim 1 or
Claim 2, wherein the "electrical" screen consists of a laminar distribution of electrically conducting material, e.g. carbon black and/or graphite.
4. A switching device according to Claim 1 or
Claim 2, wherein the "electrical" screen consists of a very thin aluminium or copper foil.
5. A switching device according to any one of
Claims 2 to 4, wherein the "electrical" screen is conductively connected to the ferrite pot.
6. A contactless electronic switching device substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2943911A DE2943911B1 (en) | 1979-10-31 | 1979-10-31 | Electronic, non-contact switching device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2062242A true GB2062242A (en) | 1981-05-20 |
Family
ID=6084787
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8031207A Withdrawn GB2062242A (en) | 1979-10-31 | 1980-09-26 | Contactless electronic switching device |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS56107640A (en) |
| DE (1) | DE2943911B1 (en) |
| FR (1) | FR2469048A1 (en) |
| GB (1) | GB2062242A (en) |
| IT (1) | IT1149229B (en) |
| SE (1) | SE8006315L (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0187810A1 (en) * | 1984-06-27 | 1986-07-23 | Digital Products Corporation | Methods and apparatus employing spontaneous resonance |
| EP0395770A2 (en) * | 1980-10-29 | 1990-11-07 | Square D Company | Proximity switch |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3244507C2 (en) * | 1981-12-08 | 1986-02-27 | Werner Turck Gmbh & Co Kg, 5884 Halver | Magnetic field dependent inductive proximity switch |
| DE3427498C2 (en) * | 1984-07-26 | 1986-08-07 | Ifm Electronic Gmbh, 4300 Essen | Electronic, preferably non-contact switching device |
| DE3438998A1 (en) * | 1984-10-25 | 1986-04-30 | Werner Turck Gmbh & Co Kg, 5884 Halver | Inductive proximity switch which can be installed flush in a metal wall |
| DE3722334A1 (en) * | 1987-07-07 | 1989-02-09 | Ifm Electronic Gmbh | ELECTRONIC, CONTACTLESS SWITCHGEAR |
| DE3722335A1 (en) * | 1987-07-07 | 1989-01-19 | Ifm Electronic Gmbh | ELECTRONIC, PREFERABLY CONTACTLESS SWITCHGEAR |
| DE4023529C3 (en) * | 1990-06-11 | 1995-12-07 | Ifm Electronic Gmbh | Inductive, capacitive or optical proximity switch |
| DE4111297C1 (en) * | 1991-04-08 | 1992-06-17 | Ifm Electronic Gmbh, 4300 Essen, De | |
| DE4114763C1 (en) * | 1991-05-06 | 1992-11-05 | Ifm Electronic Gmbh, 4300 Essen, De | |
| DE4023502A1 (en) * | 1990-07-24 | 1992-02-06 | Ifm Electronic Gmbh | Electronic switch with e.g. opto-electronic proximity sensor |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3292052A (en) * | 1963-09-19 | 1966-12-13 | Cutler Hammer Inc | Proximity switching system |
| GB1078176A (en) * | 1964-10-13 | 1967-08-02 | Tesla Np | Inductive measuring device |
| US3469015A (en) * | 1967-01-13 | 1969-09-23 | Sierracin Corp | Conductive panel |
| GB1195782A (en) * | 1967-09-05 | 1970-06-24 | Eltra Corp | Electronic Conductor Detector and Indicator |
| FR1592392A (en) * | 1968-11-20 | 1970-05-11 | ||
| DE1966213B2 (en) * | 1969-10-10 | 1974-01-17 | Ifm Electronic Geraete Gmbh & Co Kg, 4300 Essen | Electronic, contactless working distance indicator. Eliminated from: 1951137 |
| US3659194A (en) * | 1970-11-25 | 1972-04-25 | Alfred A Blackerby | Magnetic sensor having a heat treated housing for collimating the sensor{40 s flux |
| DE2220944C2 (en) * | 1972-04-28 | 1974-02-14 | Guenther Dipl.-Ing. 2209 Sushoern Weber | Electronic, contactless switching device |
| JPS523706Y2 (en) * | 1973-09-14 | 1977-01-26 |
-
1979
- 1979-10-31 DE DE2943911A patent/DE2943911B1/en not_active Ceased
-
1980
- 1980-09-10 SE SE8006315A patent/SE8006315L/en not_active Application Discontinuation
- 1980-09-26 GB GB8031207A patent/GB2062242A/en not_active Withdrawn
- 1980-10-23 IT IT25523/80A patent/IT1149229B/en active
- 1980-10-27 JP JP14949280A patent/JPS56107640A/en active Pending
- 1980-10-28 FR FR8023061A patent/FR2469048A1/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0395770A2 (en) * | 1980-10-29 | 1990-11-07 | Square D Company | Proximity switch |
| EP0395770A3 (en) * | 1980-10-29 | 1991-06-05 | Square D Company | Proximity switch |
| EP0187810A1 (en) * | 1984-06-27 | 1986-07-23 | Digital Products Corporation | Methods and apparatus employing spontaneous resonance |
| EP0187810A4 (en) * | 1984-06-27 | 1987-12-07 | Digital Products Corp | Methods and apparatus employing spontaneous resonance. |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1149229B (en) | 1986-12-03 |
| SE8006315L (en) | 1981-05-01 |
| IT8025523A0 (en) | 1980-10-23 |
| DE2943911B1 (en) | 1981-06-04 |
| JPS56107640A (en) | 1981-08-26 |
| FR2469048A1 (en) | 1981-05-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |