US2210770A - Magnetic sound recording - Google Patents
Magnetic sound recording Download PDFInfo
- Publication number
- US2210770A US2210770A US290696A US29069639A US2210770A US 2210770 A US2210770 A US 2210770A US 290696 A US290696 A US 290696A US 29069639 A US29069639 A US 29069639A US 2210770 A US2210770 A US 2210770A
- Authority
- US
- United States
- Prior art keywords
- record carrier
- width
- polar
- sound recording
- magnetic
- 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
Links
- 238000013459 approach Methods 0.000 description 2
- 238000009738 saturating Methods 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 230000004907 flux Effects 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S29/00—Metal working
- Y10S29/028—Magnetic recording digest
Definitions
- This invention relates to magnetic sound recording and particularly to erasing heads'or electromagnets for imparting a uniform magnetic condition to a telegraphone record carrier as it approaches the recording head or magnet.
- Erasing heads have been employed that establish a saturating magnetic field and a weaker leakage field through which the record carrier passes in succession, the fields being in the longitudinal direction of the record carrier but of opposite sense.
- the two fields were obtained by forming the magnetic core with a pole piece,- at the side of the core at which the record carrier departs from the core, that projects beyond its associated cor-e leg and extends along the record carrier to terminate in a polar tip.
- the polar surfaces were made but slightly wider than the record carrier as it was thought that narrow polar surfaces and the attendant; high flux densities would insure uniform results. intensity noise or disturbing sounds would appear in the reproduction, thus indicating that the erasing system had not established an entirely uniform magnetic condition in all parts of the record carrier.
- An object of the present invention is to provide a magnetic structure or erasing head that is more eflicient and effective than the prior designs.
- An object is to provide an erasing head of the type in which a high intensity saturating field and a lower intensity leakage field act in succession on the record carrier, the erasing head having such width with respect to the rece ord carrier that lateral fluctuations of the record carrier do not destroy the homogeneity of the leakage field. More specifically, an object is to provide an erasing head having polar surfaces of from two to four times the width of the record carrier that travels along the polar surfaces.
- Fig. 1 is a somewhat diagrammatic side elevation of an embodiment of the invention.
- Fig. 2 is a plan view of the same.
- the reference numeral l identifies the approximately circular core of a magnet having a winding 2 for establishing a strong unidirectional magnetic field at the gap 3 across which the record carrier or band 4 travels in the direction indicated by the arrow m.
- the pole piece 5 at the approach side of the core has It was observed, however, that low a hat surface along which the band it travels towards the gap 8, and the pole piece 8 at the departure side of the erasing magnet is extended along the band 4, beyond the associated core leg, to terminate in a polar tip I.
- the magnetic field at the gap 3 is in the di- 5 rectlon indicated by the arrow 0. and several lines of force are indicated by the dotted lines a.
- the field at the polar tip I is indicated generally by the arrow 11 and the paths of typical lines of force are shown by the lines I).
- the width of the polar surfaces is approximately three times that of the record carrier 4, and the leakage field, as indicated by lines D, is substantially parallel to the direction of travel of the record carrier.
- Small lateral fluctuations of the record carrier do not destroy the homogeneity of the leakage field, and the magnetization characteristic of the carrier as it leaves the polar tip 1 is therefore substantially constant in spite of lateral fluctuations that cannot be entirely eliminated in a practical magnetic recorder.
- the width ratio of 3 to I is not critical. Disturbing residiual noises will be substantially eliminated when the polar surfaces are twice the width of the record carrier if the lateral fluctuations are held to a low value. Increase of the polar width beyond about four times that of the record carrier will not add materially to the suppression of residual noise.
- the polar surfaces are of uniform width but it will be apparent that the essential requirement is that the width of the polar tip I be adequate to insure a homogeneous leakage fleld.
- the width of the core at the gap 3 may be somewhat smaller, if desired, but it is usually preferable and economical to have constant width polar sinfaces.
- an erasing head comprising a core having pole pieces spaced apart by a gap across which the record carrier travels, and a direct current winding on the core, the pole piece at the departure side of the core being extended along the record t5 carrier to form a leakage polar tip having a width from two to four times the width of the record carrier.
- each pole piece has a polar surface along which said record carrier travels, and said polar surfaces are of a constant width equal to from two to four times the width of the record carrier.
Description
g- 6, 1940- R. MULLER-ERNESTI 2.210.770
MAGNETIC SOUND RECORDING Filed Aug. 17, 1939 Patented Aug. 6, 1940 UNITED STATES ammo MAGNETIC SOUND RECORDING Rolf Miiller-Ernesti, Berlin, Germany, assignor to Licentla Patcnt-Verwaltungs-Gesellschaft,
Berlin, Germany Application August M, 1939, Serial No. 290,696 In Germany August 24, 1938 2 Claims.
This invention relates to magnetic sound recording and particularly to erasing heads'or electromagnets for imparting a uniform magnetic condition to a telegraphone record carrier as it approaches the recording head or magnet.
Erasing heads have been employed that establish a saturating magnetic field and a weaker leakage field through which the record carrier passes in succession, the fields being in the longitudinal direction of the record carrier but of opposite sense. The two fields were obtained by forming the magnetic core with a pole piece,- at the side of the core at which the record carrier departs from the core, that projects beyond its associated cor-e leg and extends along the record carrier to terminate in a polar tip. In accordance with the usual design of other erasing magnets, the polar surfaces were made but slightly wider than the record carrier as it was thought that narrow polar surfaces and the attendant; high flux densities would insure uniform results. intensity noise or disturbing sounds would appear in the reproduction, thus indicating that the erasing system had not established an entirely uniform magnetic condition in all parts of the record carrier.
An object of the present invention is to provide a magnetic structure or erasing head that is more eflicient and effective than the prior designs. An object is to provide an erasing head of the type in which a high intensity saturating field and a lower intensity leakage field act in succession on the record carrier, the erasing head having such width with respect to the rece ord carrier that lateral fluctuations of the record carrier do not destroy the homogeneity of the leakage field. More specifically, an object is to provide an erasing head having polar surfaces of from two to four times the width of the record carrier that travels along the polar surfaces.
These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawing in which:
Fig. 1 is a somewhat diagrammatic side elevation of an embodiment of the invention; and
Fig. 2 is a plan view of the same.
In the drawing, the reference numeral l identifies the approximately circular core of a magnet having a winding 2 for establishing a strong unidirectional magnetic field at the gap 3 across which the record carrier or band 4 travels in the direction indicated by the arrow m. The pole piece 5 at the approach side of the core has It was observed, however, that low a hat surface along which the band it travels towards the gap 8, and the pole piece 8 at the departure side of the erasing magnet is extended along the band 4, beyond the associated core leg, to terminate in a polar tip I.
The magnetic field at the gap 3 is in the di- 5 rectlon indicated by the arrow 0. and several lines of force are indicated by the dotted lines a. The field at the polar tip I is indicated generally by the arrow 11 and the paths of typical lines of force are shown by the lines I).
As shown in Fig. 2, the width of the polar surfaces is approximately three times that of the record carrier 4, and the leakage field, as indicated by lines D, is substantially parallel to the direction of travel of the record carrier. Small lateral fluctuations of the record carrier do not destroy the homogeneity of the leakage field, and the magnetization characteristic of the carrier as it leaves the polar tip 1 is therefore substantially constant in spite of lateral fluctuations that cannot be entirely eliminated in a practical magnetic recorder.
The width ratio of 3 to I is not critical. Disturbing residiual noises will be substantially eliminated when the polar surfaces are twice the width of the record carrier if the lateral fluctuations are held to a low value. Increase of the polar width beyond about four times that of the record carrier will not add materially to the suppression of residual noise.
As illustrated, the polar surfaces are of uniform width but it will be apparent that the essential requirement is that the width of the polar tip I be adequate to insure a homogeneous leakage fleld. The width of the core at the gap 3 may be somewhat smaller, if desired, but it is usually preferable and economical to have constant width polar sinfaces.
I claim:
1. In magnetic sound recording apparatus, an erasing head comprising a core having pole pieces spaced apart by a gap across which the record carrier travels, and a direct current winding on the core, the pole piece at the departure side of the core being extended along the record t5 carrier to form a leakage polar tip having a width from two to four times the width of the record carrier.
2. In magnetic sound recording apparatus, an erasing head as claimed in claim 1, wherein 5 each pole piece has a polar surface along which said record carrier travels, and said polar surfaces are of a constant width equal to from two to four times the width of the record carrier.
' ROLF mm.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE212669X | 1938-08-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2210770A true US2210770A (en) | 1940-08-06 |
Family
ID=5809258
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US290696A Expired - Lifetime US2210770A (en) | 1938-08-24 | 1939-08-17 | Magnetic sound recording |
Country Status (4)
Country | Link |
---|---|
US (1) | US2210770A (en) |
CH (1) | CH212669A (en) |
FR (1) | FR859259A (en) |
NL (1) | NL53432C (en) |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2425857A (en) * | 1943-09-24 | 1947-08-19 | Walter C Barnes | Apparatus for detecting flaws in rails |
US2427421A (en) * | 1940-06-22 | 1947-09-16 | Rieber Frank | Apparatus and method for making and analyzing geophysical records |
US2428002A (en) * | 1945-03-09 | 1947-09-30 | Edward L Barrett | Wire type recording and reproducing apparatus |
US2532803A (en) * | 1945-01-09 | 1950-12-05 | Gen Electric | Magnetic recording, reproducing, and erasing apparatus |
US2535481A (en) * | 1946-10-15 | 1950-12-26 | Brush Dev Co | Demagnetizing apparatus for magnetic recorders |
US2536029A (en) * | 1946-12-05 | 1951-01-02 | Armour Res Found | Magnetic record member |
US2635149A (en) * | 1949-12-03 | 1953-04-14 | Wilcox Gay Corp | Erasing means for magnetic recorders |
US2655561A (en) * | 1948-08-09 | 1953-10-13 | Lawrence H Connell | Apparatus for magnetic recording |
US2666813A (en) * | 1949-01-12 | 1954-01-19 | Armour Res Found | Magnetic duplicating method and means |
US3060279A (en) * | 1957-11-06 | 1962-10-23 | Emi Ltd | Magnetic transducing heads |
US3117065A (en) * | 1959-09-02 | 1964-01-07 | Magnetic Film And Tape Company | Method and apparatus for making magnetic recording tape |
US4043297A (en) * | 1973-11-17 | 1977-08-23 | Basf Aktiengesellschaft | Device for the magnetic orientation of magnetic recording media |
-
0
- NL NL53432D patent/NL53432C/xx active
-
1939
- 1939-08-17 US US290696A patent/US2210770A/en not_active Expired - Lifetime
- 1939-08-19 CH CH212669D patent/CH212669A/en unknown
- 1939-08-22 FR FR859259D patent/FR859259A/en not_active Expired
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2427421A (en) * | 1940-06-22 | 1947-09-16 | Rieber Frank | Apparatus and method for making and analyzing geophysical records |
US2425857A (en) * | 1943-09-24 | 1947-08-19 | Walter C Barnes | Apparatus for detecting flaws in rails |
US2532803A (en) * | 1945-01-09 | 1950-12-05 | Gen Electric | Magnetic recording, reproducing, and erasing apparatus |
US2428002A (en) * | 1945-03-09 | 1947-09-30 | Edward L Barrett | Wire type recording and reproducing apparatus |
US2535481A (en) * | 1946-10-15 | 1950-12-26 | Brush Dev Co | Demagnetizing apparatus for magnetic recorders |
US2536029A (en) * | 1946-12-05 | 1951-01-02 | Armour Res Found | Magnetic record member |
US2655561A (en) * | 1948-08-09 | 1953-10-13 | Lawrence H Connell | Apparatus for magnetic recording |
US2666813A (en) * | 1949-01-12 | 1954-01-19 | Armour Res Found | Magnetic duplicating method and means |
US2635149A (en) * | 1949-12-03 | 1953-04-14 | Wilcox Gay Corp | Erasing means for magnetic recorders |
US3060279A (en) * | 1957-11-06 | 1962-10-23 | Emi Ltd | Magnetic transducing heads |
US3117065A (en) * | 1959-09-02 | 1964-01-07 | Magnetic Film And Tape Company | Method and apparatus for making magnetic recording tape |
US4043297A (en) * | 1973-11-17 | 1977-08-23 | Basf Aktiengesellschaft | Device for the magnetic orientation of magnetic recording media |
Also Published As
Publication number | Publication date |
---|---|
CH212669A (en) | 1940-12-15 |
FR859259A (en) | 1940-12-14 |
NL53432C (en) | 1900-01-01 |
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