GB2155619A - Rotation measuring devices, tachometers - Google Patents
Rotation measuring devices, tachometers Download PDFInfo
- Publication number
- GB2155619A GB2155619A GB08405387A GB8405387A GB2155619A GB 2155619 A GB2155619 A GB 2155619A GB 08405387 A GB08405387 A GB 08405387A GB 8405387 A GB8405387 A GB 8405387A GB 2155619 A GB2155619 A GB 2155619A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light
- chopping
- optical
- optical fibre
- tachometer
- 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- Withdrawn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
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
- G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
- G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
- G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
- G01P3/486—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by photo-electric detectors
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optical Transform (AREA)
Abstract
An optical tachometer or other device for providing information relating to rotating structures, comprises a light-chopping or varying structure 1 coupled or adapted to be coupled to rotating means 2 and an optical fibre arranged for conveying light from a remote light source 5 to the light- chopping or varying structure and for conveying reflected light to a detector 12. The structure 1 comprises alternate absorbing and reflecting portions 4 and may be associated with means to vary the wavelength of the reflected light. Circuitry associated with the detector may determine the frequency or the period of received pulses. The apparatus may be used for angular position measurement. <IMAGE>
Description
SPECIFICATION
Improvements relating to tachometers and similar devices
This invention relates to tachometers and similar devices for providing information relating to rotating structures (e.g. speed) and relates more specifically to such devices utilising optical fibre means.
According to one aspect of the present invention an optical tachometer comprises a light-chopping or varying structure coupled or adapted to be coupled to rotating means for measuring the speed of rotation thereof and an optical fibre arranged for directing light from a remote light source on to the lightchopping or varying structure which has associated with it light reflecting means effective for reflecting pulses of said light or light of varying intensity back along the optical fibre to speed measuring and/or indicating means.
In carrying out the present invention the light reflecting means preferably forms part of the light-chopping or varying structure and the light reflecting means may comprise a multiplicity of reflecting elements positioned around the peripheral surface of a rotatable disc which constitutes the light-chopping structure. However, it is also envisaged that the reflecting means could be separate from the light-chopping structure but arranged to reflect light back through the structure to the optical fibre. In such cases the light-chopping structure could be provided with a multiplicity of opaque radial spokes or bands which serve to interrupt the reflection of light from the light reflecting means and thereby produce light pulses at a frequency dependent upon the speed of rotation of the light-chopping structure.
The light source which may for example comprise a light emitting diode may be arranged to launch continuous light into one end of the optical fibre through a beam splitter. The other end of the optical fibre is appropriately located in close proximity to the light chopping structure and light pulses reflected back along the optical fibre in response to rotation of the chopping structure pass through the beam splitter to pulse counting means.
The pulse counting means may be arranged effectively to count the frequency of the light pulses, or, alternatively, it may be arranged to measure the period of the light pulses as an indication of the speed of rotation of the lightchopping structure.
It will be apparent from the foregoing that the tachometer construction according to the present invention enables the same optical fibre to be used both for transmitting light to the light-chopping or varying structure and for conveying the reflected light back to the speed measuring and/or indicating means.
By way of example one embodiment of the present invention will now be described with reference to the accompanying single-figure drawing which is a diagrammatic representation of an optical tachometer.
Referring to the drawing, the optical tachometer illustrated comprises a light-chopping disc structure 1 coupled to a rotatable shaft 2 the speed of which is to be measured. The outer peripheral surface 3 of the disc structure 1 is provided with a multiplicity of circumferentially-spaced light reflecting elements 4.
Continuous light produced by electrical energisation of a light-emitting diode 5 is directed through a sphere lens 6 into a directional beam splitter 7 and then passes through a further sphere lens 8 into an optical fibre 9 optically coupled thereto. The light is transmitted along the optical fibre 9 to the far end thereof which is coupled to a collimating sphere lens 10 located in close proximity to the peripheral surface 3 provided with the light reflecting elements 4.
In response to rotation of the shaft 2 and the light-chopping disc structure 1 fixedly coupled thereto light from the optical fibre 9 impinging on the surface 3 will be alternately reflected and absorbed by the surface 3 of the chopping disc 1 and consequential light pulses of a frequency dependent upon the speed of rotation of the disc 1 will be reflected back along the optical fibre 9 to the directioanl beam splitter 7. These light pulses pass through the beam splitter 7 and a sphere lens 11 and impinge on a photo-diode 1 2 in order to produce an electrical pulse output corresponding in frequency to the reflected light pulses from the light-chopping disc 1.
After amplification of the electrical pulse output from the photo-diode 1 2 by an amplifier 1 3 the pulses are fed to a clock-controlled counter 14 which produces an output 1 5 representative of the rotational speed of the chopper disc 1 and shaft 2.
The counter 1 4 may alternatively be arranged to measure the period of the light pulses rather than their frequencies in which case the number of reflecting elements 4 on the disc 1 may be reduced to a minimum (e.g. 1 or 2) and a fast clock counter control utilised. The latter arrangement would be especially advantageous for the measurement of rotational speeds over a wide range of speeds (e.g. O to 5500 rpm).
Although the invention has been specifically described with reference to a tachometer it is also contemplated that the invention could also be applied to other similar devices, such as shaft encoders for providing an indication of the angular position of a rotating structure and in such cases the light reflected from light reflecting means associated with the lightvarying structure may be modified as by a change in wavelength before being reflected back through the optical fibre to wavelength detection means at the remote end of the optical fibre.
Claims (6)
1. An optical tachometer or other device for providing information relating to rotating structures, comprising a light-chopping or varying structure coupled or adapted to be coupled to rotating means for measuring for example the speed of rotation thereof and an optical fibre arranged for conveying light from a remote light source to the light-chopping or varying structure which has associated with it light reflecting means effective for reflecting pulses of said light or light of varying intensity back along the optical fibre to speed or other measuring and/or indicating means.
2. An optical tachometer or other device as claimed in claim 1, in which the light reflecting means forms part of the light-chopping or varying structure.
3. An optical tachometer or other device as claimed in claim 2, in which the light reflecting means comprises a multiplicty of reflecting elements positioned around the peripheral surface of a rotatable disc which constitutes the light-chopping structure
4. An optical tachometer or other device as claimed in any preceding claim in which the light source is arranged to launch continuous light into one end of the optical fibre through a beam splitter while the other end of the optical fibre is located in close proximity to the light-chopping structure so that light pulses reflected back along the optical fibre in response to rotation of the chopping structure pass through the beam splitter to pulse counting means.
5. An optical tachometer or other device as claimed in claim 4, in which the counting means counts the frequency of the light pulses or measures the period of the light pulses.
6. An optical tachometer or other device substantially as hereinbefore described with refernce to the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08405387A GB2155619A (en) | 1984-03-01 | 1984-03-01 | Rotation measuring devices, tachometers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08405387A GB2155619A (en) | 1984-03-01 | 1984-03-01 | Rotation measuring devices, tachometers |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8405387D0 GB8405387D0 (en) | 1984-04-04 |
| GB2155619A true GB2155619A (en) | 1985-09-25 |
Family
ID=10557418
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08405387A Withdrawn GB2155619A (en) | 1984-03-01 | 1984-03-01 | Rotation measuring devices, tachometers |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2155619A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0221333A1 (en) * | 1985-10-09 | 1987-05-13 | Crane Co. | Fiber optic rotation rate encoder |
| US4767164A (en) * | 1985-10-09 | 1988-08-30 | Crane Co. | Fiber optic rotation rate encoder |
| GB2438872A (en) * | 2006-06-09 | 2007-12-12 | Univ Southampton | Movement detector apparatus and detecting method |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB946140A (en) * | 1961-05-04 | 1964-01-08 | Ford Motor Co | Improvements in or relating to torquemeters |
| GB1312797A (en) * | 1970-08-11 | 1973-04-04 | Girling Ltd | Vehicle braking systems |
| GB1385038A (en) * | 1971-03-03 | 1975-02-26 | Maschf Augsburg Nuernberg Ag | Speed measuring arrangement including apparatus for measuring the speed of relative movement between two parts |
| GB1432502A (en) * | 1974-04-26 | 1976-04-22 | Lumenition Ltd | Devices for measuring shaft rpm |
| GB2052053A (en) * | 1979-05-31 | 1981-01-21 | Asea Ab | Measuring fields using an optical modulator |
| GB2054138A (en) * | 1979-06-25 | 1981-02-11 | Yazaki Corp | Travel distance signal generator for a vehicle |
-
1984
- 1984-03-01 GB GB08405387A patent/GB2155619A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB946140A (en) * | 1961-05-04 | 1964-01-08 | Ford Motor Co | Improvements in or relating to torquemeters |
| GB1312797A (en) * | 1970-08-11 | 1973-04-04 | Girling Ltd | Vehicle braking systems |
| GB1385038A (en) * | 1971-03-03 | 1975-02-26 | Maschf Augsburg Nuernberg Ag | Speed measuring arrangement including apparatus for measuring the speed of relative movement between two parts |
| GB1432502A (en) * | 1974-04-26 | 1976-04-22 | Lumenition Ltd | Devices for measuring shaft rpm |
| GB2052053A (en) * | 1979-05-31 | 1981-01-21 | Asea Ab | Measuring fields using an optical modulator |
| GB2054138A (en) * | 1979-06-25 | 1981-02-11 | Yazaki Corp | Travel distance signal generator for a vehicle |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0221333A1 (en) * | 1985-10-09 | 1987-05-13 | Crane Co. | Fiber optic rotation rate encoder |
| US4767164A (en) * | 1985-10-09 | 1988-08-30 | Crane Co. | Fiber optic rotation rate encoder |
| GB2438872A (en) * | 2006-06-09 | 2007-12-12 | Univ Southampton | Movement detector apparatus and detecting method |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8405387D0 (en) | 1984-04-04 |
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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) |