WO2002095455A2 - Optical encoder for a flat dc motor - Google Patents

Optical encoder for a flat dc motor Download PDF

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Publication number
WO2002095455A2
WO2002095455A2 PCT/US2002/016345 US0216345W WO02095455A2 WO 2002095455 A2 WO2002095455 A2 WO 2002095455A2 US 0216345 W US0216345 W US 0216345W WO 02095455 A2 WO02095455 A2 WO 02095455A2
Authority
WO
WIPO (PCT)
Prior art keywords
armature
optical sensor
light
segments
insulating material
Prior art date
Application number
PCT/US2002/016345
Other languages
French (fr)
Other versions
WO2002095455A3 (en
Inventor
Christophe Durand
Original Assignee
Otis Elevator Company
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 Otis Elevator Company filed Critical Otis Elevator Company
Publication of WO2002095455A2 publication Critical patent/WO2002095455A2/en
Publication of WO2002095455A3 publication Critical patent/WO2002095455A3/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales

Definitions

  • This invention concerns an optical encoder for a flat DC motor, and in particular a drive motor for opening and closing elevator car doors.
  • Such an encoder is used to provide data to the elevator control about the moving speed of the doors and their position.
  • flat DC motors on the market which include a fixed inductor formed by a disk-shaped plate supporting some permanent magnets placed in a circle around the plate's axis, a rotating armature on a printed circuit, formed by a flat disk made of an insulating material on which a number of coils are printed by depositing a conductive metal, for example copper, and said coils comprise radial segments separated by intermediary gaps in the insulating material of the disk.
  • This induction disk is installed on a shaft on which a rotating element can also be installed, for example a drive pulley belonging to the car doors drive system.
  • Direct current is supplied to the armature by brushes sliding over a collector formed on the armature shaft, to which the coils are connected.
  • This invention intends to remedy the drawbacks of known encoders mounted on the end of a shaft and therefore proposes a new type of encoder which does not increase the motor thickness.
  • the invention thus concerns an optical encoder for a flat DC motor of the above mentioned type, where said encoder is composed of a photo-reflective light emitter sending out a light beam, and a light sensor, where said light beam falls on the area of the armature disk on which the metallic segments are printed, so that when the armature rotates, the light beam is alternately reflected by the highly reflective metallic segments and by the low reflective gaps of insulating material, returning a reflected beam with a luminosity that alternately varies at the rate of succession of the segments and gaps, where said reflected beam is received by the light sensor and is transformed into a pulsed electrical signal which is transmitted to an elevator operation control.
  • This signal represents the car doors' movement perfectly.
  • a stream of constant frequency electrical signals is produced at the outlet of the light sensor.
  • the signal obtained at the outlet of the sensor will have a constant intensity, since the armature itself is not moving either. The result is that the shape of the received signals keeps the control constantly informed of any door movement.
  • the optical encoder advantageously includes a second photo-reflective optical sensor mounted in a fixed position at an angular displacement of half a metallic segment in the clockwise or counterclockwise direction, with respect to the first optical sensor.
  • This second optical sensor makes it possible to determine the direction of rotation of the armature and thereby the displacement direction of the car doors.
  • the resolution of the information furnished by the electrical signal depends on the number of metallic segments. An excellent resolution is obtained with an armature comprising one hundred metallic segments. RTFF DFSCRTPTTON OF TT F FT T IRF.S
  • Fig. 1 is a view of an axial cut through a flat motor for driving elevator car doors, where said motor is equipped with an optical encoder according to the invention, and
  • Fig. 2 is an exploded perspective view of the main elements of the flat motor and the encoder.
  • Fig. 1 illustrates a flat DC motor 10 designed to drive a schematically shown rotating pulley 12, which for example is part of a not illustrated elevator car door drive system.
  • the motor includes a housing 14 in the form of a hollow shell closed at one end and open at the other.
  • the open side ends in a peripheral flange 13 that extends to the outside.
  • the housing is closed by a cover 15 applied to the flange.
  • the housing contains a fixed inductor 16 and a rotating armature 18.
  • the inductor is composed of a circular plate 20 with a number of attached permanent magnets 22 which have been polarized alternately north and south, and are placed concentrically with respect to the plate's axis.
  • the armature 18 is of the printed circuit type. It includes a circular disk 24 made of an insulating material, for example epoxy. Coils are printed on the disk by depositing a conductive metal, for example copper. In order not to encumber the figures, only the radial portions or segments 28 of the coils have been illustrated. These metallic segments are relatively bright or reflective and are separated from each other by epoxy gaps 29 which are relatively dull.
  • the armature also includes a circular piece 30 comprising a one-piece disk- shaped part 32, a portion of which forms a sleeve 34.
  • the armature disk 24 is pressed on the sleeve 34 and abuts against the disk-shaped part 32.
  • the annular part 30 contains a shaft 36 which is securely attached to the latter by means of a screw 38.
  • the pulley 12 is also a solidly rotating part of the shaft 36.
  • the armature is supplied with electric current by two brushes 40 impelled by springs 42 so that their ends contact the armature plate 24.
  • the shaft 36 is mounted to rotate in the housing 14 by means of not illustrated bearings.
  • the cover 15 of the housing contains a cavity 43 in which an optical sensor 44 is installed; it comprises an infrared light emitter 46 and a light receiver 48 mounted next to each other.
  • the optical sensor is located on the cover so that it faces the area of the armature on which the segments 28 are printed.
  • a flat annular disk 50 is located between the cover and the housing and forms a mask containing a hole 52. The latter is placed so that it faces the optical sensor. The edge of the flat disk is clamped between the housing flange 13 and the cover 15.
  • the armature 18 When the armature 18 receives electric current it rotates at constant speed and drives the pulley 12. During that movement the beam 54 passing through the hole 52 in disk 50 is alternately reflected by the segments 28 and the gaps 29. The return beam 56 is sent back by a copper segment at a relatively high light intensity, and the one sent back by a gap 29 made of an insulating material has a relatively weak light intensity since the insulating material is relatively dull. The light reflected by the segments and the gaps is captured by the receiver 48 which transforms it into a pulsed electrical signal.
  • a second (not illustrated) photo-reflective sensor which is separated by a half-segment in the clockwise or counterclockwise direction, can be provided to determine the rotating direction of the armature.
  • the electrical signals at the outlets of the two optical sensors are communicated to the elevator control which is thereby kept constantly informed of the car door's position, its movement and displacement speed.
  • the invention has thus made it possible to create an optical sensor which does not increase the motor thickness.
  • This encoder has the advantage of being adaptable to all existing flat motors without modification of their structure.

Abstract

The invention concerns an optical encoder for a flat DC motor comprising a fixed inductor (16), a rotating armature (18) on a printed circuit, composed of a flat disk (24) made of an insulating material with low reflective power, on which a number of coils are printed by depositing a highly reflective conductive metal, where said coils include radial segments (28) separated by intermediary gaps (29) of an insulating material. The encoder comprises a photo-reflective sensor (44) composed of a light emitter (46) which emits a beam of light (54) and a light receiver (48), and where when the armature rotates, said light beam (54) is alternately reflected by the highly reflective metallic segments (28) and by the low reflection gaps (29) of an insulating material, producing a reflected beam (56) the luminosity of which varies alternately according to the rate of succession of the segments (28) and the gaps (29), and said reflected beam is transformed by the light receiver (48) into a pulsed electrical signal.

Description

PTTΓAT FNΓ ΠFR FOR A FT, AT DΓ MOTOR
SC.OPF OF THF. TNVF.NTTON
This invention concerns an optical encoder for a flat DC motor, and in particular a drive motor for opening and closing elevator car doors. Such an encoder is used to provide data to the elevator control about the moving speed of the doors and their position.
TRΓHNTΓ. AT Ft A ΓKΓ.ROT TND OF TH TNVFNTION Motors for closing elevator car doors are known in the technology, where the optical encoder is mounted at the end of the motor shaft. Such an arrangement has the drawbac of increasing the total thickness of the motor, which is a problem in certain cases because the motor is generally installed on the car's lintel and in that location the available space between the car and the shaft is relatively narrow. There are also flat DC motors on the market which include a fixed inductor formed by a disk-shaped plate supporting some permanent magnets placed in a circle around the plate's axis, a rotating armature on a printed circuit, formed by a flat disk made of an insulating material on which a number of coils are printed by depositing a conductive metal, for example copper, and said coils comprise radial segments separated by intermediary gaps in the insulating material of the disk.
This induction disk is installed on a shaft on which a rotating element can also be installed, for example a drive pulley belonging to the car doors drive system. Direct current is supplied to the armature by brushes sliding over a collector formed on the armature shaft, to which the coils are connected.
DFSCRTPTION OF THF TNVF.NTTON
This invention intends to remedy the drawbacks of known encoders mounted on the end of a shaft and therefore proposes a new type of encoder which does not increase the motor thickness.
OT-4685 To that end the applicant thought it advisable to produce an optical encoder for the above mentioned flat motor, which uses the difference that exists between the reflective power of the metallic segments and the reflective power of the gaps made of an insulating material, which separate the segments. The invention thus concerns an optical encoder for a flat DC motor of the above mentioned type, where said encoder is composed of a photo-reflective light emitter sending out a light beam, and a light sensor, where said light beam falls on the area of the armature disk on which the metallic segments are printed, so that when the armature rotates, the light beam is alternately reflected by the highly reflective metallic segments and by the low reflective gaps of insulating material, returning a reflected beam with a luminosity that alternately varies at the rate of succession of the segments and gaps, where said reflected beam is received by the light sensor and is transformed into a pulsed electrical signal which is transmitted to an elevator operation control.
This signal represents the car doors' movement perfectly. In fact under normal operation, where the flat motor drives the door at a constant speed, a stream of constant frequency electrical signals is produced at the outlet of the light sensor. By contrast, if the door is stopped either because it is in one of its extreme open or closed positions, or because it was accidentally blocked in an intermediary position, the signal obtained at the outlet of the sensor will have a constant intensity, since the armature itself is not moving either. The result is that the shape of the received signals keeps the control constantly informed of any door movement.
The optical encoder advantageously includes a second photo-reflective optical sensor mounted in a fixed position at an angular displacement of half a metallic segment in the clockwise or counterclockwise direction, with respect to the first optical sensor. This second optical sensor makes it possible to determine the direction of rotation of the armature and thereby the displacement direction of the car doors.
The resolution of the information furnished by the electrical signal depends on the number of metallic segments. An excellent resolution is obtained with an armature comprising one hundred metallic segments. RTFF DFSCRTPTTON OF TT F FT T IRF.S
A configuration of the invention will now be described by means of the attached drawings, where:
Fig. 1 is a view of an axial cut through a flat motor for driving elevator car doors, where said motor is equipped with an optical encoder according to the invention, and
Fig. 2 is an exploded perspective view of the main elements of the flat motor and the encoder.
DFTAIT FD DFSCRTPTTON OF A PRFFFRRFD rONFTOI TR ATTON
Fig. 1 illustrates a flat DC motor 10 designed to drive a schematically shown rotating pulley 12, which for example is part of a not illustrated elevator car door drive system.
The motor includes a housing 14 in the form of a hollow shell closed at one end and open at the other. The open side ends in a peripheral flange 13 that extends to the outside. The housing is closed by a cover 15 applied to the flange. The housing contains a fixed inductor 16 and a rotating armature 18.
The inductor is composed of a circular plate 20 with a number of attached permanent magnets 22 which have been polarized alternately north and south, and are placed concentrically with respect to the plate's axis.
The armature 18 is of the printed circuit type. It includes a circular disk 24 made of an insulating material, for example epoxy. Coils are printed on the disk by depositing a conductive metal, for example copper. In order not to encumber the figures, only the radial portions or segments 28 of the coils have been illustrated. These metallic segments are relatively bright or reflective and are separated from each other by epoxy gaps 29 which are relatively dull.
The armature also includes a circular piece 30 comprising a one-piece disk- shaped part 32, a portion of which forms a sleeve 34. The armature disk 24 is pressed on the sleeve 34 and abuts against the disk-shaped part 32. The annular part 30 contains a shaft 36 which is securely attached to the latter by means of a screw 38. The pulley 12 is also a solidly rotating part of the shaft 36.
The armature is supplied with electric current by two brushes 40 impelled by springs 42 so that their ends contact the armature plate 24. The shaft 36 is mounted to rotate in the housing 14 by means of not illustrated bearings. The cover 15 of the housing contains a cavity 43 in which an optical sensor 44 is installed; it comprises an infrared light emitter 46 and a light receiver 48 mounted next to each other. The optical sensor is located on the cover so that it faces the area of the armature on which the segments 28 are printed. A flat annular disk 50 is located between the cover and the housing and forms a mask containing a hole 52. The latter is placed so that it faces the optical sensor. The edge of the flat disk is clamped between the housing flange 13 and the cover 15.
OPF ATTON
The operation of the optical sensor of the invention will now be described. When the armature 18 receives electric current it rotates at constant speed and drives the pulley 12. During that movement the beam 54 passing through the hole 52 in disk 50 is alternately reflected by the segments 28 and the gaps 29. The return beam 56 is sent back by a copper segment at a relatively high light intensity, and the one sent back by a gap 29 made of an insulating material has a relatively weak light intensity since the insulating material is relatively dull. The light reflected by the segments and the gaps is captured by the receiver 48 which transforms it into a pulsed electrical signal.
According to the invention a second (not illustrated) photo-reflective sensor, which is separated by a half-segment in the clockwise or counterclockwise direction, can be provided to determine the rotating direction of the armature. The electrical signals at the outlets of the two optical sensors are communicated to the elevator control which is thereby kept constantly informed of the car door's position, its movement and displacement speed.
The invention has thus made it possible to create an optical sensor which does not increase the motor thickness. This encoder has the advantage of being adaptable to all existing flat motors without modification of their structure.

Claims

T ATMS
1. An optical sensor for a DC motor, of a type comprising a fixed inductor ( 16), a rotating armature (18) securely attached to a shaft (36), where said armature is composed of a flat disk (24) made of an insulating material with a low reflectivity surface, a plurality of coils formed of a highly reflective conductive metal located on the disk, where said coils include radial segments (28) separated by intermediary gaps (29) made of an insulating material, characterized in that the optical sensor comprises a photo-reflective sensor (44) composed of a light emitter (46) which emits a beam of light (54), and a light receiver (48), where said beam falls on the armature disk area on which the metallic segments (28) are printed, so that when the armature rotates, the beam (54) is reflected alternately by the highly reflective metallic segments (28) and by the low reflection insulating material gaps (29), producing a reflected beam (56) whose luminosity varies alternately according to the rate of succession of the segments (28) and the gaps (29), and wherein said reflected beam is transformed by the light receiver (48) into a pulsed electrical signal.
2. An optical sensor as claimed in claim 1, characterized in that the armature (18) is mounted to rotate inside a hollow housing (14) closed at one end and open at the other, where the open end is closed by a cover (15), and that the photo-reflective sensor (44) is located in a cavity (43) formed in the thickness of the cover.
3. An optical sensor as claimed in claim 1 and 2, characterized in that it also contains an annular plate forming a mask (50), located between the cover (15) and the armature (18), said plate having a hole (52) which allows a light beam (54) from the light emanating from the emitter (46) to pass through it.
4. An optical sensor as claimed in claim 2 and 3, characterized in that the peripheral edge of the annular plate (50) is clamped between the edge of the hollow housing and the cover.
5. An optical sensor as claimed in one of the preceding claims, characterized in that the hole (52) is located in the annular plate so that the light beam (54) falls on the armature disk area where the metallic segments are located.
6. An optical sensor as claimed in claim 1, characterized in that it includes a second photo-reflective sensor mounted in a fixed position at an angular displacement of half a metallic segment in the clockwise or counterclockwise direction with respect to the first optical sensor.
PCT/US2002/016345 2001-05-23 2002-05-23 Optical encoder for a flat dc motor WO2002095455A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0106807 2001-05-23
FR01/06807 2001-05-23

Publications (2)

Publication Number Publication Date
WO2002095455A2 true WO2002095455A2 (en) 2002-11-28
WO2002095455A3 WO2002095455A3 (en) 2003-03-13

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PCT/US2002/016345 WO2002095455A2 (en) 2001-05-23 2002-05-23 Optical encoder for a flat dc motor

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5907199A (en) * 1997-10-09 1999-05-25 Ut Automotive Dearborn, Inc. Electric motor providing multi-directional output
US6396785B1 (en) * 1998-01-22 2002-05-28 Olympus Optical Co., Ltd. Optical disk apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5907199A (en) * 1997-10-09 1999-05-25 Ut Automotive Dearborn, Inc. Electric motor providing multi-directional output
US6396785B1 (en) * 1998-01-22 2002-05-28 Olympus Optical Co., Ltd. Optical disk apparatus

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