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
  • G01D5/28—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 deflection of beams of light, e.g. for direct optical indication
  • G01D5/30—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 deflection of beams of light, e.g. for direct optical indication the beams of light being detected by photocells
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
  • G01B11/275—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing wheel alignment
  • G01B11/2755—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing wheel alignment using photoelectric detection means

Definitions

• the present invention pertains to a measuring instru- ment, and more particularly relates to an optoelectronic measuring scale which is constructed to determine and to indicate the exact position at which a beam of light emitted from a radiation source, for instance a laser projector, impinges thereon through a window or an opening.
• a radiation source for instance a laser projector
• Optoelectronic integrated circuits are used in the form of detector matrices equipped with so-called CCD-devices.
• Such devices charge coupled devic ⁇ es
• CCD-devices are normally very small (10-15 ⁇ m) and despite the fact that each separate matrix may include a large number of elements, about 2,000 elements, the total geometric extension of such a matrix is relatively short. Matrices which comprise charge coupled devices cannot therefore be used for measuring scales of rela ⁇ tively long lengths.
• the object of the present invention is to provide an optoelectronic measuring scale of relatively short extension, about 0.5 metre, and the invention is mainly characterized, to this end, in that the measuring scale includes a row of discrete photoelements firmly mounted on a circuit board or the like and connected conduct- ively to a microprocessor attached to the circuit board; in that firmly mounted in the measuring scale is a diffusor which functions to distribute radiation inten ⁇ sity of incident light in the measuring scale over a plurality of mutually adjacent photoelements; and in that the microprocessor functions to compare the inten ⁇ sity of the light emitted by respective photoelements and, subsequent to calculating the centre-of-gravity of the broadened intensity curve, to produce signals which cause the exact position of the light beam on the mea ⁇ suring scale to be displayed on a display device con ⁇ nected to said scale.
• a diffusor in the beam path of the measuring scale is justified because the light beam emitted, for instance, by a laser projector has a small beam diver ⁇ gence and a small degree of intensity distribution.
• the pitch or spacing of the photoelements mounted on a circuit board in the measuring scale is greater than the intensity distribution of the light beam.
• Figure 1 is a schematic, longitudinal view of an inven- tive measuring scale including a row of photo ⁇ elements and a microprocessor;
• Figure 2 is a cross-sectional view of the measuring scale shown in Figure 1; and
• Figure 3 illustrates the detection principles of the measuring scale.
• the inventive measuring scale has the form of an opto ⁇ electronic detector unit. It comprises an elongated profiled body 19 which is enclosed by walls 20, 21, 22 on three sides thereof. A fourth side, the upper side, is provided with an elongated opening 28. The imperfo- rate surfaces along the sides of the opening 28 are provided with a linear metric graduation whose length is greater than 30 cm. Each end of the body 19 is closed with an end-plate 23.
• the body 19 is mounted on a circuit board 24 on which a number of known electronic components are mounted. Since these components have no actual bearing on the invention, they will not be described here. Also mount ⁇ ed on the circuit board 24 is a long row of discrete photoelements 25, preferably phototransistors. These photoelements are connected conductively to a micropro ⁇ cessor 26, a so-called microchip processor, which is attached to the circuit board 24 and which detects the intensity of the light emitted by each individual photo- element 25 and, on the basis thereof, calculates the centre-of-gravity point of a light beam incident on the measuring scale 18. This results in output currents which cause the result to be shown in digit form on a display unit 27 connected indirectly to the circuit board 24, in a known manner.
• the measuring scale components are powered electric- ally by a number of batteries 30 mounted in the body 19.
• the microprocessor 26 is also intended to activate an indicator lamp 33 when incident light on the measuring scale 18 activates the microprocessor 26 so as to cal ⁇ culate the aforesaid centre-of-gravity position.
• the indicator lamp 33 is placed within the body 19 of the measuring scale so that it can be seen easily by the person carrying out the measurements.
• an elongated lens 31 Arranged in the opening 28 on the upper side of the body 19 is an elongated lens 31 which enlargens the detector surface of the measuring scale 18 so as to capture any movements made by a beam source.
• the lens 31 has a low position in the opening 28, thereby protecting the lens 31 and shielding said lens from oblique incident light that may have an undue negative influence on the photo ⁇ elements 24.
• the inventive measuring scale is intended for use together with a beam source, for in- stance a laser projector.
• a laser projector produces coherent light which has only a small beam divergence. This means that the light will have high intensity on a very small irradiated surface.
• the intensity distribution is achieved so that light from the beam source is able to illuminate a plurality of mutually adjacent photoele ⁇ ments 25 in the measuring scale 18. This is effected by mounting beneath the lens 31 in the body 19 a diffusor 32 which functions to distribute incident light in the measuring scale 18 to the respective photoelements 25.
• Figure 3a illustrates an intensity curve of a laser beam emitted from a laser projector.
• Figure 3b illustrates an intensity distribution curve having the same radia ⁇ tion quantity
• Figure 3c shows the same curve on a larger scale.
• the curve 3c illustrates the light inten ⁇ sity emitted by a number of mutually adjacent photo ⁇ elements 41-47 in the measuring scale 18 and detected by the microprocessor 26.
• the microprocessor 26 determines the precise position of the light beam on the measuring scale 18, by calculating the centre-of-gravity of the broadened curve and displays this precise position in a so-called window on the display unit 27.
• the invention is not restricted to the exemplified embodiments thereof and that these embodiments can be modified within the scope of the following* Claims.
• the light de ⁇ tecting elements used in the measuring scale may be photodiodes.
• the measuring result may be reproduced in a way other than that described in the specification.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optical Transform (AREA)
• Photometry And Measurement Of Optical Pulse Characteristics (AREA)

Priority Applications (3)

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Publications (1)

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Family Applications (1)

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Citations (1)

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• 1991
  • 1991-04-30 SE SE9101302A patent/SE468368B/sv not_active IP Right Cessation
• 1992
  • 1992-04-23 US US08/140,107 patent/US5453839A/en not_active Expired - Lifetime
  • 1992-04-23 WO PCT/SE1992/000265 patent/WO1992019931A1/en active IP Right Grant
  • 1992-04-23 EP EP92910002A patent/EP0610198B1/en not_active Expired - Lifetime
  • 1992-04-23 DE DE69222053T patent/DE69222053T2/de not_active Expired - Lifetime
  • 1992-05-20 TW TW081103928A patent/TW223679B/zh not_active IP Right Cessation

Patent Citations (1)

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