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WO1982000728A1 - Transducteur optique de position - Google Patents

Transducteur optique de position Download PDF

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Publication number
WO1982000728A1
WO1982000728A1 PCT/DK1981/000080 DK8100080W WO8200728A1 WO 1982000728 A1 WO1982000728 A1 WO 1982000728A1 DK 8100080 W DK8100080 W DK 8100080W WO 8200728 A1 WO8200728 A1 WO 8200728A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
code
code disc
light source
conductors
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.)
Ceased
Application number
PCT/DK1981/000080
Other languages
English (en)
Inventor
Dev Center Aps Klemar
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO1982000728A1 publication Critical patent/WO1982000728A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H03M1/12—Analogue/digital converters
    • H03M1/22—Analogue/digital converters pattern-reading type
    • H03M1/24—Analogue/digital converters pattern-reading type using relatively movable reader and disc or strip
    • H03M1/26—Analogue/digital converters pattern-reading type using relatively movable reader and disc or strip with weighted coding, i.e. the weight given to a digit depends on the position of the digit within the block or code word, e.g. there is a given radix and the weights are powers of this radix

Definitions

  • the present invention relates to an optical position transducer comprising a code disc and a lighting device which are mutually movable, sa id code disc comprising a support of electrically insulating material on which electrical conductors with interposing light sensitive elements are provided, wherein the conductors are substantially concentric, and the interposed light sensitive elements are arranged in a binary code pattern , and wherein the lighting device is arranged so as to provide a narrow line-shaped light beam extending over all the conductors substandially radially with respect thereto.
  • a phosphor light source is mounted on an arm which rotates with a shaft carrying a pointer of a utility meter, and the angular position of which is to be detected for remote indication .
  • the light source provides radiation wh ich selectively activates l ight sensitive sensor elements on a stationary code disc as a function of the shaft position .
  • the known code disc comprises ten sensor elements each comprising a couple of conductors provided on an insulating support and separated from each other by a photo res istive material forming an electric connection between the conductors when illuminated.
  • the code disc is positioned on or connected to the shaft, the angular position of which is to be detected.
  • the code disc has several ring shaped concentric information tracks of alternate clear and opaque areas arranged in a certain coded pattern .
  • the code disc is positioned between a light source and a l ight sensitive unit, such as a set of photo cells which are selectively activated of light from the light source dependent on the angular position of the disc and consequently of the shaft, in order to provide binary output signals.
  • Such optical transducers are disadvantageous in that they require comp lex and heavy optical systems to parallelize and focus the light from a light source to a narrow beam to be directed through the clear areas of the code disc on to the photo cells. Thereby the trans ducer necessarily gets a considerable extent in the direction of the beam.
  • the code disc is often made of g lass and consequently relatively heavy, a secure support is required in order to prov ide and ma intain the necessary very precise position of the light source, code disc, and photo cells with respect to each other. Because of this necessary high accuracy the system, besides, is sensitive to temperature f luctuations, variations of light level and mechan ical changes.
  • the object of the present invention is to provide an optica l position transducer of the kind stated in the introductory part which transducer is particularly compact and simple to manufacture, and by which the disadvantages of the prior constructions are avoided, and according to the invention this is achieved by the fact that the light sensitive elements are positioned in pairs of tracks between a central supply voltage conductor and outer reading conductors and that the code pattern on the code disc is shaped as a spiral , a circle, or a circular arc . Thereby only one supply voltage conductor is required for each two information tracks.
  • the code pattern of a photo sensitive material can be provided in any way but according to the invention it has proved appropriate that the code pattern cons ists of non-etched away or non -covered parts of a light sensitive coating applied on to the entire code disc because this as far as the manufacturing technique is concerned is particularly simple and, besides, enables the manufacture thereof in smaller dimensions as the printed circuit board techniques .
  • the device for providing the light line comprises a stationary light source and a light conducting member which is rotatab le around said source by means of the shaft, the position of which is to be detected, said light conducting member ending in a narrow slit located radially with respect to the code disc over the code pattern thereof.
  • a particu larly low constructional height of the entire transducer may be achieved when the light conductor has a central bore for the light source and a bore extending radially therefrom, the outer end of wh ich is covered by an oblique mirror for directing the light from the light source down through the underlying radial sl it .
  • the device for providing the light line comprises a stationary lamp and a light proof cover plate with a light permeable slit over the code pattern, said cover plate being rotatable with the shaft and positioned between the lamp and the code disc.
  • the signals provided by the code disc are low-level binary signals which normally require amplification and other kinds of processing
  • a light proof housing In which the code disc is mounted may advantageously also contain an electrical processing circuit for the signals provided by the code disc.
  • Fig . 1 shows an embodiment of an optical position transducer according to the invention
  • Fig . 2 at a larger scale and seen from above a section of a code disc in the transducer of fig. 1
  • Fig. 3 a section of the code disc of fig. 1 at a still larger scale
  • Fig. 4 another embodiment of a code disc for use in an opti cal position transducer accord ing to the invention
  • Fig. 5 a perspective view of a transducer with a rotatable cover plate for providing a light line
  • Fig. 6 the same as in fig. 5 but showing an axial section
  • Fig. 7a-7c a light conductor seen from below, in section , and from above, respectively
  • Fig. 8 a further embodiment of a position transducer according to the invention in which the light conductor in Figs. 7a-7c is used .
  • Fig. 1 shows an optical position transducer in the form of an angular motion transducer having a stationary code disc 1 and a lighting device 2 for providing a light line on the code disc.
  • the code disc 1 comprises an electrically insulating support 3, e. g. of a ceramic material , in which a code track 4 with connecting leads 5 is arranged in an outer peripheral area.
  • the code track 4 shown at an enlarged scale in the sectional views in figs. 2 and 3 comprises a plurality of electrically conducting rings, supply voltage conductors 6 and reading conductors 7, respectively, and light sensitive material 8 positioned therebetween , e. g .
  • the CdSe-, Ge- or Si-material which , when i lluminated, becomes electrically conducting in order to transfer the electrical voltage from a supply voltage conductor 6 to a reading conductor 7.
  • the voltage taken off from the reading conductors is preferably transferred via signal processing circuits which appropri ately are arranged in the transducer on a separate plate or on the code disc itself.
  • the signal processing does not form part of the present invention and will not be further explained.
  • the signals produced are used in a normal way for supervision, control, remote indication etc.
  • the electrically conducting rings 6 and 7 consisting of e.g. gold, silver, copper are - as will appear from figs.
  • the light sensitive material is preferably arranged in accordance with a normal binary code pattern, particularly in accordance with the Gray-code, but also other arrangements of the light sensitive material are possible for providing trigonometrical and other functions.
  • the pattern of the light sens itive material may be performed by coating, such as vapour deposition or spray deposition of a light sensitive material on the total surface of the disc and a following etching-away or covering with a light proof material of those portions of the coating not forming part of the code pattern desired .
  • FIG. 4 An embodiment of a code disc with a spiral shaped code track is shown in fig. 4 in which only four information tracks corresponding to a four bit transducer are illustrated for the sake of clarity.
  • two supply voltage rings 6 are connected to a common termina l 15 while the reading rings 7 are connected to separate terminals 16.
  • the position of the light sensitive material accord ing to the Gray-code is apparent from the drawing.
  • the light line for illuminating the light sensitive material 8 between the supply voltage rings and the reading rings 6 and 7 may be provided in different ways.
  • the width of the light line must be smaller than half of the shortest length of an area 8 in order to determine the position exactly.
  • the lighting device 2 consists of a stationar ⁇ ly mounted light source 9 arranged within a hollow shaft 10 which is connected to the shaft (not shown), the position of which is to be detected.
  • the light from the lamp is directed on to the code track 4 through a tube 11 , the lower end of which is performed as a narrow slit positioned radially with respect to the code disc.
  • the transducer is built into a light proof housing (not shown) so that only the light sensitive material positioned immediately under the light slit is conducting .
  • a further embodiment of the lighting device is shown in figs. 5 and 6.
  • a cover plate 12 e.g. an opaque plate or a glass sheet with an opaque covering, connected to the rotating shaft, is provided with a light slit 13 through which the light from a stationary light source 14 is directed onto the code track 4.
  • the light conductor 17 shown consists of a member of e.g. light metal having a hub part 18 in wh ich a shaft 19 may be mounted.
  • a cylindrical bore 20 is arranged for accomodating a light source 21 .
  • a bore 22 extends from the bore 20 through one half of the l ight conductor, and at the outer end the bore 22 is covered by an oblique mirror 23.
  • the outermost part of the light conductor in the area under the mirror is, as will appear from figs. 7a-7c, provided with a slit 24 extending from outside and into the bore 22 so that the light emitted from the l ight source has a beam path through the light conductor as shown by arrows in fig. 7b.
  • the width of the slit may by e.g. about 50 ⁇ m.
  • the position transducer shown in fig . 8, in which transducer the light conductor 17 is used, comprises a housing of e.g. aluminium, having an upper part 25 which is light proof assembled with a lower part 26.
  • a light source 21 is firmly mounted in the upper part 20 and extends downwards into the bore 20 in the light conductor 17 arranged in a cavity 27 in the housing, the shaft 19 of said light conductor being rotatably mounted in bearing bushings 28 in the lower part 26.
  • Below the lower part 26 the shaft 19 supports a coupling device 29, e.g. a coupling fork, for connection with a shaft or an instrument pointer, the rotational position of which is to be detected .
  • a coupling device 29 e.g. a coupling fork, for connection with a shaft or an instrument pointer, the rotational position of which is to be detected .
  • a code disc 1 is mounted together with a plate
  • a specific use of the transducer according to the invention may be achieved by performing the code track as a program track in a program device for controlling machines etc.
  • a further use of the transducer may be achieved by providing the rotatable shaft with a plurality of fixed rotational positions corresponding to the positions of the code disc. Thereby the transducer may operate as a kind of change-over switch enabling an extremely large number of positions.
  • optical position transducers of mechanically small dimensions may be provided by the invention , said transducers simultaneously having a high resolution, e. g. 8-12 bits.
  • the mechanical construction is simple and does not require an accurate mutual positioning of a plurality of components opposite each other.
  • the movable part such as the light conductor between the light source and the code track, can be performed with a very low weight and, consequently, with a minimum torque and inertia which enables the use of the transducer in connection with mechanical precision measuring instruments. All in all the construction can be performed at relatively low costs but nevertheless provides a high reliability, among other things because of the relatively few component parts of the transducer.

Landscapes

  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Optical Transform (AREA)

Abstract

Un transducteur optique de position comprend un disque de code (1) et un dispositif d'eclairage (2) pouvant se deplacer mutuellement. Le disque de code comprend une piste (4) de code sur un support (3) electriquement isolant, cette piste de code comprenant une pluralite de conducteurs electriques (6, 7) avec des elements (8) interposes sensibles a la lumiere. En placant les conducteurs electriques parallelement ou concentriquement et en disposant les elements interposes sensibles a la lumiere selon une configuration de code binaire et en produisant un rayon de lumiere en forme de ligne s'etendant sur tous les conducteurs, l'on obtient un transducteur digital de position absolue.
PCT/DK1981/000080 1980-08-21 1981-08-20 Transducteur optique de position Ceased WO1982000728A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK360480A DK360480A (da) 1980-08-21 1980-08-21 Optisk positionstransducer
DK3604/80800821 1980-08-21

Publications (1)

Publication Number Publication Date
WO1982000728A1 true WO1982000728A1 (fr) 1982-03-04

Family

ID=8124770

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1981/000080 Ceased WO1982000728A1 (fr) 1980-08-21 1981-08-20 Transducteur optique de position

Country Status (3)

Country Link
EP (1) EP0059730A1 (fr)
DK (1) DK360480A (fr)
WO (1) WO1982000728A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4034980C1 (fr) * 1990-11-03 1992-04-16 Messerschmitt-Boelkow-Blohm Gmbh, 8012 Ottobrunn, De

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303490A (en) * 1963-02-28 1967-02-07 Perkin Elmer Corp Photoconductive coded disc encoder
US3470385A (en) * 1967-04-03 1969-09-30 Singer General Precision Optical encoder comprising easily removable coded cylinder
US3815126A (en) * 1971-03-01 1974-06-04 Northern Illinois Gas Co Shaft encoder for apparatus having luminous phosphor source
US4086488A (en) * 1976-10-18 1978-04-25 General Medical Appliance Research Corporation Digital pressure gauge system
SU641484A1 (ru) * 1977-07-11 1979-01-05 Институт Полупроводников Ан Украинской Сср Фотоэлектрический преобразователь угла поворота вала в код
SU643942A1 (ru) * 1976-11-12 1979-01-25 Институт Полупроводников Ан Украинской Сср Преобразователь перемещени в код

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303490A (en) * 1963-02-28 1967-02-07 Perkin Elmer Corp Photoconductive coded disc encoder
US3470385A (en) * 1967-04-03 1969-09-30 Singer General Precision Optical encoder comprising easily removable coded cylinder
US3815126A (en) * 1971-03-01 1974-06-04 Northern Illinois Gas Co Shaft encoder for apparatus having luminous phosphor source
US4086488A (en) * 1976-10-18 1978-04-25 General Medical Appliance Research Corporation Digital pressure gauge system
SU643942A1 (ru) * 1976-11-12 1979-01-25 Институт Полупроводников Ан Украинской Сср Преобразователь перемещени в код
SU641484A1 (ru) * 1977-07-11 1979-01-05 Институт Полупроводников Ан Украинской Сср Фотоэлектрический преобразователь угла поворота вала в код

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Derwent's abstract No J 5650B/40, SU 641 484 *
Derwent's abstract No J 5716B/40 SU 643 942 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4034980C1 (fr) * 1990-11-03 1992-04-16 Messerschmitt-Boelkow-Blohm Gmbh, 8012 Ottobrunn, De

Also Published As

Publication number Publication date
EP0059730A1 (fr) 1982-09-15
DK360480A (da) 1982-02-22

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