GB2170912A - Instrumentation apparatus provided with a magnetic scale - Google Patents
Instrumentation apparatus provided with a magnetic scale Download PDFInfo
- Publication number
- GB2170912A GB2170912A GB08602013A GB8602013A GB2170912A GB 2170912 A GB2170912 A GB 2170912A GB 08602013 A GB08602013 A GB 08602013A GB 8602013 A GB8602013 A GB 8602013A GB 2170912 A GB2170912 A GB 2170912A
- Authority
- GB
- United Kingdom
- Prior art keywords
- coil
- signal
- instrumentation
- magnetic scale
- excitation
- 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- Withdrawn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
- 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
- G01D5/12—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 using electric or magnetic means
- G01D5/14—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 using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—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 using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
- G01D5/204—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 using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils
- G01D5/2046—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 using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by a movable ferromagnetic element, e.g. a core
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/003—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring position, not involving coordinate determination
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
Abstract
An instrumentation apparatus which comprises a magnetic scale on which a magnetized pattern is formed with a prescribed wavelength and a magnetic head which is positioned opposite to said magnetic scale and constructed by surrounding excitation core with excitation coil and signal coil 14, being characterized in that a capacitor 17 is connected in parallel to the signal coil for turning with that frequency component of an output signal from said signal coil (14) which is required for instrumentation, e.g. the second harmonic of the current supplied to the excitation coil. <IMAGE>
Description
SPECIFICATION
Instrumentation apparatus provided with a magnetic scale
This invention relates to an instrumentation apparatus provided with a magnetic scale, and more particularly to that type wherein an output signal from the magnetic head is freed of unnecessary harmonic components.
As is well known, an instrumentation apparatus designed to measure, for example, lengths and angles by a magnetic scale is widely used in various fields, because measurement is effected with high precision. Recently the magnetic scale apparatus is also widely applied to automatic control. The apparatus comprises a magnetic scale for forming a magnetized pattern with a prescribed wavelength A (normally of the order of about 200 microns), and a magnetic head set opposite to said magnetic scale. The apparatus is characterized in that either magnetic scale or magnetic head is fixed; the remaining unit is connected to a movable body; a signal issued from the magnetic head is electrically processed -when the movable body travels, thereby determining the distance covered by the moving body.
The above-mentioned instrumentation apparatus has the drawbacks that the travelling speed of either magnetic scale or magnetic head is not fixed; measurement should always be made even when these members stand at rest, and the scale and head should be kept free of forceful contact to minimize the wear of the magnetic scale and magnetic head.
To date, therefore, the magnetic head has been a magnetic flux sensing type. This magnetic type of the magnetic head is constructed by winding an excitation coil and signal-issuing coil around an excitation core set opposite to the magnetic scale. When the excitation coil is supplied with high frequnecy current, the signal-issuing coil sends forth a signal (corresponding to the moving distance of a body) which is derived by modulating said excitation current by a magnetized pattern of the magnetic scale. The distance covered by a moving body is measured by electrically processing said modulated signal. Recently, a multigap type excitation core has come into to produce an output of high precision and high level.
An output signal issued from the signal coil of the magnetic head involved in the aforementioned instrumentation apparatus contains a harmonic wave component having a frequency an integral number of times higher than the frequency (fo) of said excitation current. At the present technical level, an output signal would attain the object of effecting electric processing for instrumentation, provided it has a frequency twice as high as (2fo) that of said excitation current. If, therefore, any other harmonic component than the abovementioned frequency component of (2fo) should overlap the output signal, errors would undesirably be generated in the values of instrumentation.
This invention has been accomplished in view of the above-mentioned circumstances, and is intended to provide an instrumentation apparatus which is constructed by connecting a capacitor in parallel with the signal coil of the magnetic head and drawing and that signal from said signal coil which has a frequency adapted for instrumentation, thereby preventing unnecessary harmonic components from exerting harmful effects on instrumentation and assuring the accurate measurement of the travelling distance of a movable body.
To attain the above-mentioned object, this invention provides a magnetic scale type instrumentation apparatus which comprises:
a magnetic scale in which a magnetized pattern is formed with a prescribed wavelength;
a magnetic head which is positioned opposite to said magnetic scale and provided with a excitation core surrounded with an excitation coil and signal coil;
wherein, an excitation current having a prescribed frequency is supplied to the excitation coil, and the signal coil issues an output signal obtained by modulating said excitation current by the magnetized pattern of the magnetic scale; and
which is characterized in that a capacitor is connected in parallel with the signal coil, to tune with that frequency component of the output signal from the signal coil which is required for instrumentation.
This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Figure 1 is a plan view illustrating the arrangement of a magnetic head capable of making a response by means of a magnetic flux; and
Figure 2 is a diagram showing the manner in which the signal coil of the magnetic head is connected to a processing circuit.
Description may now be made with reference to the attached drawings of an instrumentation apparatus embodying this invention.
Fig. 1 represents the arrangement of magnetic head 11 capable of making a response by means of a magnetic flux. Magentic head 11 is constructed by winding excitation coil 13 and signal coil 14 around excitation core 12.
Magnetic head 11 is positioned opposite to magnetic scale 1 5 on which a magnetized pattern having a prescribed wavelength is formed, and is made movable along magnetic scale 15.
When excitation coil 13 is supplied with excitation current having frequency (fo), signal coil 14 issues a signal obtained by modulating the excitation current by the magnetized pattern of magnetic scale 15. Signal coil 14 is connected at both ends to electric processing circuit 16. Electric processing circuit 16 electrically processes an output signal from signal coil 14, thereby issuing an instrumentation signal corresponding to the moving distance of magnetic head 11, namely, the distance covered by a moving body. Said instrumentation signal is used to regulate an automatic control apparatus or display a measured value.
Referring to Fig. 2, capacitor 17 is connected in parallel to signal coil 14. Capacitor 17 is designed to tune with that frequency component (twice as high as the frequency (fo), for example, excitation current) of an output signal from signal coil 14 which is required for instrumentation. Therefore, only that frequency component of an output signal from signal core 14 which is required for instrumentation is supplied to electric processing circuit 16, and unnecessary harmonic components are prevented from being brought to electric processing circuit 16.
With the instrumentation apparatus of this invention constructed as described above, electric processing circuit 16 only receives a signal having a frequency required for instrumentation, thus offering the advantages that instrumentation errors are prevented from taking place by the generation of unnecessary harmonic components, and the travelling distance of a movable body can be accurately determined.
The foregoing description refers to an instrumentation apparatus embodying this invention, wherein magnetic scale 15 is fixed and magnetic head 11 is made to travel. However, this invention is also applicable to an instrumentation apparatus, wherein magnetic head 11 is fixed, and magnetic scale 15 is made to travel.
Claims (3)
1. An instrumentation apparatus which involves a magnetic scale on which a magnetized pattern is formed with a prescribed wavelength, and a magnetic head which is positioned opposite to said magnetic scale and is constructed by surrouding an excitation core with an excitation coil and signal coil, and wherein said excitation coil is supplied with an excitation current having a prescribed frequency, and said signal coil issues an output signal modulated by the magnetized pattern of said magnetic scale; said instrumentation apparatus being characterized in that a capacitor connected in parallel to said signal coil is designed to tune with that frequency component of an output signal from said signal coil which has a frequency required for instrumentation.
2. The instrumentation apparatus according to claim 1, wherein the frequency with which said capacitor is designed to tune is twice as large as that of said excitation current.
3. The instrumentation apparatus provided with a magnetic scale, substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2487885A JPS61184403A (en) | 1985-02-12 | 1985-02-12 | Magnetic head apparatus for magnetic scale |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8602013D0 GB8602013D0 (en) | 1986-03-05 |
| GB2170912A true GB2170912A (en) | 1986-08-13 |
Family
ID=12150451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08602013A Withdrawn GB2170912A (en) | 1985-02-12 | 1986-01-28 | Instrumentation apparatus provided with a magnetic scale |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS61184403A (en) |
| DE (1) | DE3603565A1 (en) |
| GB (1) | GB2170912A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3903278A1 (en) * | 1989-02-03 | 1990-08-09 | Rexroth Mannesmann Gmbh | SUPPLY OF INDUCTIVE SENSORS |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3727265A1 (en) * | 1987-08-15 | 1989-02-23 | Kostal Leopold Gmbh & Co Kg | Inductive distance pickup |
| DE4031931A1 (en) * | 1990-10-06 | 1992-04-09 | Perthen Feinpruef Gmbh | INDUCTIVE LENGTH GAUGE |
| JP3292709B2 (en) * | 1999-07-01 | 2002-06-17 | エスエムシー株式会社 | Air chuck with measuring function |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB879550A (en) * | 1958-09-12 | 1961-10-11 | Standard Telephones Cables Ltd | Measurement of length of magnetisable objects |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5829468B2 (en) * | 1972-08-31 | 1983-06-22 | 日本鋼管株式会社 | Kanno impedance system |
| JPS5819966B2 (en) | 1975-05-16 | 1983-04-21 | 横河電機株式会社 | displacement converter |
| JPS562760A (en) | 1979-06-21 | 1981-01-13 | Kokusai Denshin Denwa Co Ltd <Kdd> | Cross polarization measuring unit |
| JPS5725131U (en) * | 1980-07-18 | 1982-02-09 | ||
| JPS5967403A (en) | 1982-09-24 | 1984-04-17 | Seiko Instr & Electronics Ltd | Device for detecting displacement |
-
1985
- 1985-02-12 JP JP2487885A patent/JPS61184403A/en active Pending
-
1986
- 1986-01-28 GB GB08602013A patent/GB2170912A/en not_active Withdrawn
- 1986-02-05 DE DE19863603565 patent/DE3603565A1/en not_active Ceased
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB879550A (en) * | 1958-09-12 | 1961-10-11 | Standard Telephones Cables Ltd | Measurement of length of magnetisable objects |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3903278A1 (en) * | 1989-02-03 | 1990-08-09 | Rexroth Mannesmann Gmbh | SUPPLY OF INDUCTIVE SENSORS |
| US5027066A (en) * | 1989-02-03 | 1991-06-25 | Mannesmann Rexroth Gmbh | Inductive distance sensor using a particular oscillator impedance ratio |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61184403A (en) | 1986-08-18 |
| GB8602013D0 (en) | 1986-03-05 |
| DE3603565A1 (en) | 1986-08-14 |
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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) |