GB2226915A - Component for electrical circuits - Google Patents
Component for electrical circuits Download PDFInfo
- Publication number
- GB2226915A GB2226915A GB8923567A GB8923567A GB2226915A GB 2226915 A GB2226915 A GB 2226915A GB 8923567 A GB8923567 A GB 8923567A GB 8923567 A GB8923567 A GB 8923567A GB 2226915 A GB2226915 A GB 2226915A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tube
- detector
- source
- occt
- optical
- 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- Withdrawn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
- 230000003287 optical effect Effects 0.000 claims abstract description 33
- 229920003023 plastic Polymers 0.000 claims abstract description 7
- 239000004033 plastic Substances 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000004065 semiconductor Substances 0.000 claims description 3
- 230000003071 parasitic effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000005674 electromagnetic induction Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/12—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof structurally associated with, e.g. formed in or on a common substrate with, one or more electric light sources, e.g. electroluminescent light sources, and electrically or optically coupled thereto
- H01L31/16—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof structurally associated with, e.g. formed in or on a common substrate with, one or more electric light sources, e.g. electroluminescent light sources, and electrically or optically coupled thereto the semiconductor device sensitive to radiation being controlled by the light source or sources
- H01L31/167—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof structurally associated with, e.g. formed in or on a common substrate with, one or more electric light sources, e.g. electroluminescent light sources, and electrically or optically coupled thereto the semiconductor device sensitive to radiation being controlled by the light source or sources the light sources and the devices sensitive to radiation all being semiconductor devices characterised by potential barriers
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4295—Coupling light guides with opto-electronic elements coupling with semiconductor devices activated by light through the light guide, e.g. thyristors, phototransistors
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Optics & Photonics (AREA)
- Light Receiving Elements (AREA)
Abstract
An optically coupled current transformer, or "OCCT" comprises an optical source and an optical detector arranged for transfer of an optical signal. The optical source (e.g. an LED or laser) and the photodetector (eg a PIN diode or avalanche photodetector) are encapsulated at opposite ends of an opaque, preferably plastics tube. The device is conveniently mass produced by shrinking the tube onto the two devices. <IMAGE>
Description
COMPONENTS FOR ELECTRICAL CIRCUITS
BT CASE A23893 BOTH (0913P)
This invention relates to components for electrical circuits and in particular it relates to components which function as the equivalent of current transformers but the energy is transferred as an optical signal instead of by electro magnetic induction. It is convenient to call such a component an "OCCT" (for "optically coupled current transformer"). In order to achieve transfer as an optical signal, an OCCT normally comprises an optical source and an optical detector.
More specifically this invention is concerned with
OCCTs which have low or zero electrical capacitance and which are suitable for use at high frequencies, eg several megahertz.
Optical telecommunications requires detector circuits to convert optical signals into electrical signals.
Detector circuits comprise a primary detector, eg a photodiode, and an amplifier for amplifying the output of the primary detector. The circuit includes a feedback resistor in parallel with the amplifier. Patent specifications US 3611173 and GB 2030020B both describe circuits in which the function of the conventional feedback resistor is replaced by an OCCT. In use the LED receives the feedback signal whereby it produces an optical signal modulated with the feedback. The detector is located so as to receive the modulated light. The combination functions as the equivalent of a conventional current transformer but it improves the performance of the detector circuit because is is less susceptible to parasitic effects, eg by unwanted inductive or capacative links.
Up to the time of writing optical telecommunications systems have been limited to trunk links where relatively small numbers of detectors are required. However it is envisaged that, in the near future, optical telecommunications may extend even to the ultimate customers' terminating equipment and this will create a need for very large numbers, possibly several millions, of optical detector circuits. This would create a need to produce large numbers of circuits in which an OCCT would be advantageous. This invention is concerned with OCCTs which are suitable for large scale production.
The well known optical isolators might also be regarded as a form of OCCT but optical isolators are not intended or suitable for use in optical detector circuits as described above. As already mentioned the feedback resistor associated with an optical amplifier works at high frequency, ie at the data rate of the optical system which is usually of the order of several megahertz.
Conventional optical isolators do not perform adequately at these high frequencies. Furthermore it is desired that the linkage should have low or substantially zero capacitance. Conventional optical isolators do not have a low enough capacitance for use as OCCTs.
According to this invention an OCCT comprises an optical source and an optical detector encapsulated at opposite ends of a tube, eg an opaque plastics tube, said source and said detector being held in spaced. apart relationship by said tube.
Because of the spacing there is substantially no capacitance between the source and the detector. The source and the detector are both capable of handling modulation at high frequencies. Preferably the source and the detector are both semiconductor devices. For example the source may be an LED or a semiconductor laser; the detector may be a PIN diode or an avalanche photodetector.
According to a second aspect of this invention an OCCT is made by locating an optical source and an optical detector inside the bore of a tube and shrinking the tube to enclose the source and the detector in an operable spaced apart relationship. Conveniently the source and the detector are held in a defined spaced apart relationship during the shrinkage whereby the shrunk tube permanently holds them in an operable relationship.
The tube is preferably made of opaque, heat shrinkable plastics and the shrinking comprises heating the tube with the source and detector located therein to cause the tube to shrink.
The invention will now be described by way of example with reference to the accompanying drawings in which:
Figure 1 shows an OCCT according to the invention; and
Figure 2 illustrates one way of making the OCCT shown
in Figure 1.
As shown in Figure 1, the connector comprises a light source 10 having electrical supply leads 11 and an optical detector 12 with electrical leads 13. The light source 10 and the detector 12 are located inside the bore 15 of an opaque plastics tube 14 which, at the ends, encapsulates the source 10 and detector 12.
In use, an electric signal is applied to the source 10 which produces an optical output equivalent to the electrical signal. The optical output travels via the bore 14 to impinge on the detector 12. The detector responds to the impinging radiation and converts it back to electrical form whereby the output electrical signal is available at the leads 13. The tube 14 holds the source 10 and the detector 12 in spaced apart operabale relationship and, because it is opaque, it excludes extraneous radiation which could cause malfunction. The illustrated device is equivalent to an electrical current transformer but it is less susceptible to interference via parasitic coupling. The device can be incorporated into circuits as conveniently as a conventional component. It has substantially zero capacitance and it works at the signal frequencies used in optical telecommunications.
The manufacture, illustrated in Figure 2, of the connector is convenient for mass production. The source 10 and the detector 12 are introduced into the ends of a heat shrink plastics tube and held by clamps 21 and 22 in the spaced apart relationship which is suitable for operation. The heat shrink tube is heated to its activation temperature whereby it reduces its radial dimensions so that the two ends grip the two components.
Since the components are clamped at the required working distance they remain at this distance while the tube 20 shrinks. Selecting tubes which do not shrink longitudinally helps to preserve a desired spacing.
The process is adapted for mass production because the un-shrunk precursors are easy to assemble and large numbers can be shrunk by using a conveyor belt to move them through a heating zone. while tighter tolerances can be achieved by individually assembled components, said components are expensive and they are not available in large quantities. Our production technique makes large numbers available at low price and at a quality compatible with production specifications.
Claims (9)
1. An OCCT comprising an optical source and an optical detector encapsulated at opposite ends of a tube, said source and said detector being held in spaced apart relationship by said tube.
2. An OCCT according to claim 1, wherein the source and the detector are both semiconductor devices.
3. An OCCT according to claim 2, wherein the source is an
LED or a laser.
4. An OCCT according to either claim 2 or claim 3, wherein the detector is a PIN diode or an avalanche photodetector.
5. An OCCT according to any one of the preceding claims, in which the tube is a plastics tube.
6. An OCCT according to any one of the preceding claims, in which the tube is an opaque tube.
7. A method of making an OCCT which comprises locating an optical source and an optical detector inside and at opposite ends of a heat shrinkable tube and heating the tube to cause it to shrink and encapsulate the source an the detector.
8. A method according to claim 7, wherein the source and the detector are held apart at a pre-determined spacing while the tube shrinks.
9. A method according to either claim 7 or claim 8, in which the shrinkable tube is an opaque, plastics heat shrinkable tube.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB888824681A GB8824681D0 (en) | 1988-10-21 | 1988-10-21 | Components for electrical circuits |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8923567D0 GB8923567D0 (en) | 1989-12-06 |
| GB2226915A true GB2226915A (en) | 1990-07-11 |
Family
ID=10645577
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888824681A Pending GB8824681D0 (en) | 1988-10-21 | 1988-10-21 | Components for electrical circuits |
| GB8923567A Withdrawn GB2226915A (en) | 1988-10-21 | 1989-10-19 | Component for electrical circuits |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888824681A Pending GB8824681D0 (en) | 1988-10-21 | 1988-10-21 | Components for electrical circuits |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8824681D0 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4354115A (en) * | 1979-11-30 | 1982-10-12 | Hitachi, Ltd. | Photocoupling device |
| GB2193377A (en) * | 1986-05-21 | 1988-02-03 | Barlian Reinhold | Optoelectronic coupler |
-
1988
- 1988-10-21 GB GB888824681A patent/GB8824681D0/en active Pending
-
1989
- 1989-10-19 GB GB8923567A patent/GB2226915A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4354115A (en) * | 1979-11-30 | 1982-10-12 | Hitachi, Ltd. | Photocoupling device |
| GB2193377A (en) * | 1986-05-21 | 1988-02-03 | Barlian Reinhold | Optoelectronic coupler |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8824681D0 (en) | 1988-11-30 |
| GB8923567D0 (en) | 1989-12-06 |
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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) |