CA2257549A1 - An absolute optical encoder with analog variable-phase sinusoidal output - Google Patents
An absolute optical encoder with analog variable-phase sinusoidal output Download PDFInfo
- Publication number
- CA2257549A1 CA2257549A1 CA 2257549 CA2257549A CA2257549A1 CA 2257549 A1 CA2257549 A1 CA 2257549A1 CA 2257549 CA2257549 CA 2257549 CA 2257549 A CA2257549 A CA 2257549A CA 2257549 A1 CA2257549 A1 CA 2257549A1
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- Prior art keywords
- array
- encoding mask
- cell
- cells
- photocell array
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- 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.)
- Abandoned
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- 230000003287 optical effect Effects 0.000 title description 5
- 230000010363 phase shift Effects 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 abstract description 5
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
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
- G01D5/34776—Absolute encoders with analogue or digital scales
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optical Transform (AREA)
Abstract
The present invention represents a new method for reading the position of an encoding mask. This method significantly increases the resolution without increasing the encoding mask resolution.
An array of light cells is placed at one side of an encoding mask and consists of four elements. An array of photocells is placed on the other side and also consists of four elements. All cells in a photocell array are exposed in cell-by-cell order with 50%
overlapping. The distance between cells in a light cell array is equal to the distance between cells in a photocell array. A photocell array is aligned with a light cell array.
The output signal from a photocell array is made by summarizing the signals of each cell. The output signal from each cell is proportionate to the amount of the cell's surface being exposed.
An encoding mask is designed in such a manner, that the output signal from a photocell array is sine-wave shape analog signal. The phase shift of analog signal defines absolute position of an encoding mask above a photocell array.
An array of light cells is placed at one side of an encoding mask and consists of four elements. An array of photocells is placed on the other side and also consists of four elements. All cells in a photocell array are exposed in cell-by-cell order with 50%
overlapping. The distance between cells in a light cell array is equal to the distance between cells in a photocell array. A photocell array is aligned with a light cell array.
The output signal from a photocell array is made by summarizing the signals of each cell. The output signal from each cell is proportionate to the amount of the cell's surface being exposed.
An encoding mask is designed in such a manner, that the output signal from a photocell array is sine-wave shape analog signal. The phase shift of analog signal defines absolute position of an encoding mask above a photocell array.
Description
Hohner Corp. Tel (905) 563-4924 Fax (905) 563-7209 TOII Free 1-800-295-5693 AN ABSOLUTE OPTICAL ENCODER WITH ANALOG
VARIABLE-PHASE SINUSOIDAL OUTPUT
BACKGROUND OF THE INVENTION
Field of the invention Present invention relates to an optical system sensing light transmitted through a pattern of transparent and non-transparent areas on an encoding mask and converts it into a continuous stream of data. The combination of analog variable-phase sinusoidal and pulse signals is used to produce the output signal of an encoder.
Description of the prior art Encoders in their simplest form produces analog outputs in the form of two square waves which are 90 degrees phase-shifted relative to each other. The square waves are generated by transparent and non-transparent light areas on an encoding mask.
The resolution of this method is limited by number of lines on an encoding mask.
Other devices have attempted to increase resolution without beyond that implied by the number of lines encoded on a mask. One method has been to use multiple sources of pulsed light and multiple detectors, where each source is phase-shifted in time relative to its neighbor.
Another approach has been to modulate the intensity of the areas on an encoding mask in a smooth way so as to produce a sinusoidal analog output instead of a square wave.
5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email: hohnerC~hohner.com web: www.hohner.com BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is the schematic view of a device which represents this invention.
The view includes the following elements:
1 - A pulse generator, which synchronizes all devices.
VARIABLE-PHASE SINUSOIDAL OUTPUT
BACKGROUND OF THE INVENTION
Field of the invention Present invention relates to an optical system sensing light transmitted through a pattern of transparent and non-transparent areas on an encoding mask and converts it into a continuous stream of data. The combination of analog variable-phase sinusoidal and pulse signals is used to produce the output signal of an encoder.
Description of the prior art Encoders in their simplest form produces analog outputs in the form of two square waves which are 90 degrees phase-shifted relative to each other. The square waves are generated by transparent and non-transparent light areas on an encoding mask.
The resolution of this method is limited by number of lines on an encoding mask.
Other devices have attempted to increase resolution without beyond that implied by the number of lines encoded on a mask. One method has been to use multiple sources of pulsed light and multiple detectors, where each source is phase-shifted in time relative to its neighbor.
Another approach has been to modulate the intensity of the areas on an encoding mask in a smooth way so as to produce a sinusoidal analog output instead of a square wave.
5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email: hohnerC~hohner.com web: www.hohner.com BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is the schematic view of a device which represents this invention.
The view includes the following elements:
1 - A pulse generator, which synchronizes all devices.
2 - A light cell array controller.
3 - A light cell array.
4 - An encoding mask.
- A photocell array.
6 - An adding amplifier.
7 - A phase detector.
8 - A reference signal generator.
9 - An output controller which forms output signals.
Figure 2 is the set of sample graphs describing the method performance. The view includes the following elements:
1 - The output signal form a pulse generator 1.
2 - The output signals from a light cell array controller 2.
3 - The output signal from an adding amplifier 6.
4 - The output from a reference signal generator 9.
- A photocell array.
6 - An adding amplifier.
7 - A phase detector.
8 - A reference signal generator.
9 - An output controller which forms output signals.
Figure 2 is the set of sample graphs describing the method performance. The view includes the following elements:
1 - The output signal form a pulse generator 1.
2 - The output signals from a light cell array controller 2.
3 - The output signal from an adding amplifier 6.
4 - The output from a reference signal generator 9.
5 - The output from a phase detector 7.
Figure 3 are the schematic views of the reading principle. The views include the following elements:
1 - A light cell array of 4 elements and distance D between cells 2 - An encoding mask with period of lines T and width of line t 3 - A photocell array of 4 elements and distance D between cells and cell size d DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The measurement principle of the present invention will now be described with reference to figure 1 and figure 2.
A pulse generator (1,fig.1 ) produces a pulsing signal (1,fig.2), which synchronizes all the device's elements.
A light cell array controller (2, fig.1 ) controls a light cell array (3,fig.1 ) so the cells emit light in cell-by-cell order (2, fig.2) with 50% overlapping.
An encoding mask (4,fig.1 ) is placed between a light cell array (3,fig.1 ) and a photocell array (5,fig.1 ).
An adding amplifier (6,fig.1 ) summarizes the signals from all cells in a photocell array (5,fig.1 ) and amplifies them.
The output signal (3,fig.2) from an adding amplifier depends on the position of the encoding mask (4,fig.1 ). The phase shift of analog signal (3,fig.2) gives absolute position of an encoding mask above a photocell array (5,fig.1 ).
The output signal (3,fig.2) from an adding amplifier (6,fig.1 ) goes to a phase detector (7,fig.1 ). A reference signal generator (9,fig.1 ) produces the signal (5,fig.2) used as the reference signal in a phase detector (7,fig.1 ). The reference signal is synchronized with pulses from a pulse generator (1,fig.1 ).
A phase detector (7,fig.1 ) compares the phases of the reference signal (4,fig.2) and the signal from an adding amplifier (3,fig.2). The output signal (5,fig.2) from a phase detector (7,fig.1 ) is proportionate to the phase shift between them.
An output controller (9,fig.1 ) produces an encoder's output signal using the signal (5,fig.2) from a phase detector (7,fig.1 ).
The getting of an analog signal will now be described with reference to figure 3.
A light cell array 1 has four elements and distance D between cells. A light cell array 1 is placed on one side of an encoding mask 2. An encoding mask 2 has period of lines T
and width of line t . A photocell array 3 has four elements and distance D
between cells and size d for each cell. A photocell array 3 is placed on the other side of encoding mask 2. All four cells in a photocell array are exposed in cell-by-cell order with 50%
overlapping. An encoding mask has the next parameters t=d d T=p+___ d - size of cells in a photocell array D - period of cells in a photocell array T- period of elements in an encoding mask 2 t - size of the transparent elements in an encoding mask 2 The output signal from a photocell array 3 is the sum of signals from all four cells and has the sine-wave shape.
s REFERENCES
1. Linear differential transformer with constant amplitude and variable phase output.
US patent : 4,437,019 Inventor : Jacob Chass 2. Signal processing apparatus for pulse encoder with AID conversion and clocking.
US patent : 4,972,080 Inventor : Mitsuyuki Taniguchi 3. Angular position detector.
US patent : 4,710,889 Inventor : Thomas Wason 4. Optical encoder with variable-phase sinusoidal output.
CAN Patent : 2,196,617 Inventor : Walter Bloechle 5. Absolute optical encoder with analog variable-phase sinusoidal and pulse output.
Inventors : Walter Bloechle, Andrei Kourilovitch ~o
Figure 3 are the schematic views of the reading principle. The views include the following elements:
1 - A light cell array of 4 elements and distance D between cells 2 - An encoding mask with period of lines T and width of line t 3 - A photocell array of 4 elements and distance D between cells and cell size d DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The measurement principle of the present invention will now be described with reference to figure 1 and figure 2.
A pulse generator (1,fig.1 ) produces a pulsing signal (1,fig.2), which synchronizes all the device's elements.
A light cell array controller (2, fig.1 ) controls a light cell array (3,fig.1 ) so the cells emit light in cell-by-cell order (2, fig.2) with 50% overlapping.
An encoding mask (4,fig.1 ) is placed between a light cell array (3,fig.1 ) and a photocell array (5,fig.1 ).
An adding amplifier (6,fig.1 ) summarizes the signals from all cells in a photocell array (5,fig.1 ) and amplifies them.
The output signal (3,fig.2) from an adding amplifier depends on the position of the encoding mask (4,fig.1 ). The phase shift of analog signal (3,fig.2) gives absolute position of an encoding mask above a photocell array (5,fig.1 ).
The output signal (3,fig.2) from an adding amplifier (6,fig.1 ) goes to a phase detector (7,fig.1 ). A reference signal generator (9,fig.1 ) produces the signal (5,fig.2) used as the reference signal in a phase detector (7,fig.1 ). The reference signal is synchronized with pulses from a pulse generator (1,fig.1 ).
A phase detector (7,fig.1 ) compares the phases of the reference signal (4,fig.2) and the signal from an adding amplifier (3,fig.2). The output signal (5,fig.2) from a phase detector (7,fig.1 ) is proportionate to the phase shift between them.
An output controller (9,fig.1 ) produces an encoder's output signal using the signal (5,fig.2) from a phase detector (7,fig.1 ).
The getting of an analog signal will now be described with reference to figure 3.
A light cell array 1 has four elements and distance D between cells. A light cell array 1 is placed on one side of an encoding mask 2. An encoding mask 2 has period of lines T
and width of line t . A photocell array 3 has four elements and distance D
between cells and size d for each cell. A photocell array 3 is placed on the other side of encoding mask 2. All four cells in a photocell array are exposed in cell-by-cell order with 50%
overlapping. An encoding mask has the next parameters t=d d T=p+___ d - size of cells in a photocell array D - period of cells in a photocell array T- period of elements in an encoding mask 2 t - size of the transparent elements in an encoding mask 2 The output signal from a photocell array 3 is the sum of signals from all four cells and has the sine-wave shape.
s REFERENCES
1. Linear differential transformer with constant amplitude and variable phase output.
US patent : 4,437,019 Inventor : Jacob Chass 2. Signal processing apparatus for pulse encoder with AID conversion and clocking.
US patent : 4,972,080 Inventor : Mitsuyuki Taniguchi 3. Angular position detector.
US patent : 4,710,889 Inventor : Thomas Wason 4. Optical encoder with variable-phase sinusoidal output.
CAN Patent : 2,196,617 Inventor : Walter Bloechle 5. Absolute optical encoder with analog variable-phase sinusoidal and pulse output.
Inventors : Walter Bloechle, Andrei Kourilovitch ~o
Claims (2)
1. It is possible to significantly increase the resolution of encoder without the increasing the resolution of an encoding mask, if an encoding mask is designed in such a manner, that the output signal from a photocell array has sine-wave shape and its phase shift defines absolute position of an encoding mask above a photocell array.
2. To produce an analog output signal from a photocell array with the sine-wave shape, all cells in a photocell array must be exposed in cell-by-cell order with 50%
overlapping and an encoding mask must have the next parameters d - size of cells in a photocell array D - period of cells in a photocell array T- period of elements in an encoding mask t - size of the transparent elements in an encoding mask
overlapping and an encoding mask must have the next parameters d - size of cells in a photocell array D - period of cells in a photocell array T- period of elements in an encoding mask t - size of the transparent elements in an encoding mask
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2257549 CA2257549A1 (en) | 1999-01-05 | 1999-01-05 | An absolute optical encoder with analog variable-phase sinusoidal output |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2257549 CA2257549A1 (en) | 1999-01-05 | 1999-01-05 | An absolute optical encoder with analog variable-phase sinusoidal output |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2257549A1 true CA2257549A1 (en) | 2000-07-05 |
Family
ID=29554902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2257549 Abandoned CA2257549A1 (en) | 1999-01-05 | 1999-01-05 | An absolute optical encoder with analog variable-phase sinusoidal output |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2257549A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103557878A (en) * | 2013-07-26 | 2014-02-05 | 广东工业大学 | Absolute grating ruler multi-track encoding method |
-
1999
- 1999-01-05 CA CA 2257549 patent/CA2257549A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103557878A (en) * | 2013-07-26 | 2014-02-05 | 广东工业大学 | Absolute grating ruler multi-track encoding method |
| CN103557878B (en) * | 2013-07-26 | 2015-12-02 | 广东工业大学 | A kind of multi-track coding method of absolute grating ruler |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |