US3374477A - Shaft position digitizer - Google Patents

Shaft position digitizer Download PDF

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Publication number
US3374477A
US3374477A US380863A US38086364A US3374477A US 3374477 A US3374477 A US 3374477A US 380863 A US380863 A US 380863A US 38086364 A US38086364 A US 38086364A US 3374477 A US3374477 A US 3374477A
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United States
Prior art keywords
shaft
light
cylinder
digitizer
hole
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.)
Expired - Lifetime
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US380863A
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English (en)
Inventor
Ejiri Masakazu
Kamoi Akira
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Hitachi Ltd
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Hitachi Ltd
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    • 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
    • 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

  • ABSTRACT OF THE DISCLQSURE A shaft position digitizer wherein a plurality of hol low shafts is disposed along the same center line; each of these shafts is hollow and connected continuously or intermittently by reduction gears; light from a single stationary source is conducted through the interior of the shaft which is in correct position; and a number of photosensitive elements is disposed around the shaft at given distances; a rotational angle corresponding to a mechanical displacement to be digitized is imparted to one shaft,
  • the device is suited for miniaturization.
  • This invention relates to a new shaft position digitizer of non-contact type which has no sliding or wiping parts such as brushes.
  • the invention resides in a shaft position digitizer wherein: a plural number, m of hollow shafts each having one hole and all connected by con tinuous or intermittent reduction gears of l/n reduction ratio are coaxially disposed along the same centerline; light is passed through the hollow shaft interior; a number n of photosensitive elements are provided around each shaft at positions corresponding to 11 equal divisions of the periphery; and to one shaft, the rotational angle corresponding to a mechanical displacement to be digitized is imparted, thereby to digitize the displacement into m digits in the scale of n.
  • FIGURE 1 is a sectional view, taken along a plane through the axis of the shafts, showing one embodiment of the invention.
  • FIGURES 2(a)2(g) consist of axial sectional views showing various examples of an essential part of the device shown in FIGURE 1.
  • the embodiment of the digitizer according to the in vention shown in FIGURE 1 illustrates the case of its application to decimal three digits.
  • the digitizer is provided with three (in in the case of m digits) hollow shafts 1, 1,, and 1,, arranged coaxially on the same centerline and respectively having small holes 5, 5 and 5 on certain parts thereof.
  • the rotational angle corresponding to a mechanical displacement is applied to the shaft 1, the rotation of which is transmitted through reduction gears 2, 3, and 4 (shown in diagrammatic form) and reduced in speed by the ratio 1/10 (l/n in the case of a scale of n) to rotate the shaft 1,.
  • the rotation is further reduced by the ratio l/ 10 to rotate the shaft 1
  • 10 photosensitive elements 6 such as phototransistors in circumferential positions corresponding to 10 equal divisions (n equal divisions in the case of a scale of it) about the respective shaft.
  • the photosensitive elements 6 are adapted to receive light projected from a light source 9 through the hole in the respective shaft and are provided With leads 7 and output terminals 8.
  • the light source is in the form of a lamp 9 fitted into a socket 16 to which terminals 15 are connected.
  • the aforementioned hollow shafts 1, 1 and 1 are supported rotatably on bearings 10, which in turn are supported at the centers of supports 11, 11,, and 11 for the photosensitive elements 6.
  • the supports 11, 11,, and 11 a lamp holder 12, a terminal plate 13, and a cover 14- in combination form the rigid structure of the device.
  • a socket holder 17 is fitted in a freely attachable and detachable manner onto the terminal plate 13.
  • one phototransistor for each digit is illuminated in accordance with the rotational angle of the respective hollow shaft, said angle corresponding to a mechanical displacement, and a digital output signal is obtained through the corresponding terminal 8.
  • the inner surfaces of the hollow shafts can be provided with various means for this purpose.
  • the inner surfaces of the hollow shafts may be coated with a paint which scatters light well, or they may be plated.
  • the measures indicated in FIGURES 2(a)2(g) may be resorted to. That is, a transparent material 20 such as glass, polystyrene, or polymethyl methacrylate resin in cylindrical form of any of the various shapes shown is inserted in the hollow shafts.
  • a transparent material 20 such as glass, polystyrene, or polymethyl methacrylate resin in cylindrical form of any of the various shapes shown is inserted in the hollow shafts.
  • the transparent cylinder 20 is cut at an angle of 45 degrees to form a prism face 21 whereby a part of the incident light which comes from the said light source directly or through the previous stage is reflected toward the hole 5 and the remainder of the light is permitted to pass axially through the cylinder to the next stage, this type of cylinder being inserted in the shaft of each stage.
  • the end part 22 and the middle part 22,, of the transparent cylinder 29 are necked or made narrow so as to utilize the resulting concentration of light at these narrowed'parts.
  • cutouts or notches 23 and 24 are provided in the transparent material 20, and the total reflection and irregular reflection are utilized.
  • FTGURES 2( and 2(g) By the methods indicated in FTGURES 2( and 2(g), a hole 25 and bubbles 26 are formed in the central part of the transparent material 20, and the total re flection and irregular reflection are utilized.
  • the shaft position digitizer of the present invention has various advantageous features as is apparent from the foregoing disclosure. For example, since there are no sliding or wiping parts, the digitizer has a long serviceable life and can be used for high-speed operation. Furthermore, since the light from the light source is not required to be in the form of a parallel beam, a precision optical system is not required, and even when the digitized output is lost in the event of power failure, digitized signals of correct correspondence to the present positions can be generated upon recovery from the power failure.
  • a further advantage of this digitizer is that the construction and operation are simple, and repair and maintenance thereof are facilitated. Moreover, the construction can be readily adapted to operate wtih any number of digits, and miniaturization can be maintained even with a considerable increase in the number of digits.
  • a digitizer of m digits in the scale of n comprising a number m of hollow shafts coaxially alined on one centerline, each hollow shaft having one through hole through its wall, a continuous speed reduction mechanism of 1/ n reduction ratio intercoupling each shaft with its adjacently succeeding shaft, means to project light from a single stationary source outwardly through each said through hole, a number n of photosensitive elements disposed circumferentially about each hollow shaft at n positions equally spaced in angle, and adapted to sense said light outwardly projected, and means to cause at least one of the hollow shafts to rotate in response to a mechanical displacement to be digitized.
  • a digitizer of in digits in the scale of 11 comprising a number m of hollow shafts coaxilly alined on one centerline, each hollow shaft having one through hole through its wall, an intermittent speed reduction mechanism of l/n reduction ratio intercoupling each shaft with its adjacently succeeding shaft, means to project light from a single stationary source outwardly through each said through hole, a number n of photosensitive elements disposed circumferentially about each hollow shaft at n positions equally spaced in angle, and adapted to sense said light outwardly projected, and means to d cause at least one of the hollow shafts to rotate in response to a mechanical displacement to be digitized.
  • said means to project light outwardly through said through holes comprises a single stationary light source adapted to project light along the hollow interiors of the hollow shafts and a transparent member inserted in each of the hollow shafts, each transparent member having in its region in the vicinity of the through hole of its respective shaft a geometrically irregular part adapted to cause a portion of the said light to be directed outwardly through said hole.
  • said means to project light outwardly through said through holes comprises a single stationary light source adapted to project light along the hollow interiors of the hollow shafts and a transparent member inserted in each of the hollow shafts, each transparent member having in its region in the vicinity of the through hole of its respective shaft a geometrically irregular part adapted to cause a portion of the said light to be directed outwardly through said hole.
  • each transparent member is a transparent cylinder fully occupying the interior of the respective shaft in the vicinity of its through hole
  • the geometrically irregular part of the cylinder is selected from the group consisting of: a prism face formed on the light source end of the cylinder by cutting the cylinder along a plane at an angle of 45 degrees relative to the shaft centerline; a necked or narrowed part formed at the central port of the cylinder; a protruding part formed at the end of the cylinder away from the light source; a cutout or notch formed in the side of the cylinder; a hole through the cylinder in its central part; and air bubbles formed in the central part of the cylinder.
  • each transparent member is a transparent cylinder fully occupying the interior of the respective shaft in the vicinity of its through hole
  • the geometrically irregular part of the cylinder is selected from the group consisting of: a prism face formed on the light source end of the cylinder by cutting the cylinder along a plane at an angle of 45 degrees relative to the shaft centerline; a necked or narrowed part formed at the central part of the cylinder; a protruding part formed at the end of the cylinder away from the light source; a cutout or notch formed in the side of the cylinder; a hole through the cylinder in its central part; and air bubbles formed in the central part of the cylinder
  • References Cited Libaw and Craig A Photoelectric Decimal-Coded Shaft Digitizer, IRE Transactions, on Electronic Computers, vol. EC-23, 1953, pages 1-4.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Optical Transform (AREA)
US380863A 1963-07-10 1964-07-07 Shaft position digitizer Expired - Lifetime US3374477A (en)

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JP3535863 1963-07-10

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DE (1) DE1285769B (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4735826U (de) * 1971-05-13 1972-12-21
JPS4895646U (de) * 1972-02-15 1973-11-14
US3963351A (en) * 1975-04-14 1976-06-15 Britton Chance Multi-channel optical time-sharing apparatus having a rotating filter wheel with position-encoding means
US4201911A (en) * 1978-03-15 1980-05-06 Richard M. Glueck Shaft angle digitizer
US20040089797A1 (en) * 2000-10-17 2004-05-13 Bradley Engstrand Apparatus, a system and method for position monitoring and/or cleaning of a machine element

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2483359A (en) * 1945-11-10 1949-09-27 Veeder Root Inc Transfer mechanism for counters
US3188626A (en) * 1961-09-15 1965-06-08 Sperry Rand Corp Analogue-to-digital-converter

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2873440A (en) * 1954-10-26 1959-02-10 United Aircraft Corp Analogue-to-digital converter
GB809679A (en) * 1955-11-18 1959-03-04 Nat Res Dev Digital encoders
US2941088A (en) * 1956-12-10 1960-06-14 Baldwin Piano Co Optical encoder
DE1048035B (de) * 1957-02-11 1958-12-31 Bizerba Waagenfabrik Wilhelm K Abschaltvorrichtung fuer Waagen, insbesondere Neigungswaagen
FR1202118A (fr) * 1958-01-14 1960-01-07 Ibm France Perfectionnements aux dispositifs convertisseurs de grandeurs analogiques en valeurs numériques

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2483359A (en) * 1945-11-10 1949-09-27 Veeder Root Inc Transfer mechanism for counters
US3188626A (en) * 1961-09-15 1965-06-08 Sperry Rand Corp Analogue-to-digital-converter

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4735826U (de) * 1971-05-13 1972-12-21
JPS4895646U (de) * 1972-02-15 1973-11-14
US3963351A (en) * 1975-04-14 1976-06-15 Britton Chance Multi-channel optical time-sharing apparatus having a rotating filter wheel with position-encoding means
US4201911A (en) * 1978-03-15 1980-05-06 Richard M. Glueck Shaft angle digitizer
US20040089797A1 (en) * 2000-10-17 2004-05-13 Bradley Engstrand Apparatus, a system and method for position monitoring and/or cleaning of a machine element
US7180053B2 (en) * 2000-10-17 2007-02-20 Motion Controls, Llc Apparatus, a system and method for determining a position within a cylinder

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Publication number Publication date
DE1285769B (de) 1968-12-19

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