US4937093A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for measuring thickness of magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1989-06-30
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Granted: 1990-06-26
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Expires: 2009-06-30
Abstract
Abstract A method for measuring the thickness of a multi-layer magnetic recording medium which provides a high accuracy and which can be used for continuous on-line monitoring of product thickness. First, first and second magnetic layers are simultaneously coated onto a running nonmagnetic support to form the recording medium. The first and second magnetic layers are made of materials having different responses to fluorescent X-rays. Then, the thickness of at least one of said first and second layers is measured by exposing the recording medium to fluorescent X-rays.
Inventors
- 👤 Naoyoshi Chino
- 👤 Shinji Saito
- 👤 Toshihiko Miura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:40
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G01; G01B; G01B15/00; G01B15/02
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
104 words
A method for measuring the thickness of a magnetic recording medium, comprising the steps of: simultaneously coating first and second magnetic layers onto a running nonmagnetic support to form said recording medium, said first and second magnetic layers having different responses to fluorescent X-rays; and measuring the thickness of at least one of said first and second layers by providing in advance a calibration curve of thickness versus intensity of transmitted fluorescent X-rays, exposing said recording medium to fluorescent X-rays, measuring an intensity of said fluorescent X-rays transmitted through said recording medium, and determining said thickness from said calibration curve using the measured intensity.
Claim 2
Independent Claim
104 words
A method for measuring the thickness of a magnetic recording medium, comprising the steps of: simultaneously coating first and second magnetic layers onto a running nonmagnetic support to form said recording medium, said first and second magnetic layers having different responses to fluorescent X-rays; and measuring the thickness of at least one of said first and second layers by providing in advance a calibration curve of thickness versus intensity of transmitted fluorescent X-rays, exposing said recording medium to fluorescent X-rays, measuring an intensity of said fluorescent X-rays transmitted through said recording medium, and determining said thickness from said calibration curve using the measured intensity.
Claim 3
Dependent Claim
34 words
The method of claim 1, wherein said first layer contains an abrasive and said second layer contains no abrasive, said first layer being an upper layer and said second layer being a lower layer.
Claim 4
Dependent Claim
41 words
The method of claim 2, wherein a thickness in μm of said first layer multiplied by a portion by weight in percent of said abrasive relative to a total weight of magnetic material of said first layer is 0.5 or more.
Claim 5
Dependent Claim
43 words
The method of claim 3, wherein a spot diameter S in mm of said fluorescent X-rays is given by: ##EQU4## where t is said thickness in μm of said first layer and V is said portion by weight in percent of said abrasive.
Claim 6
Dependent Claim
25 words
The method of claim 2, wherein said abrasive is selected from the group consisting of oxides, nitrides, and carbides of chromium, aluminum, titanium, and silicon.
Claim 7
Dependent Claim
41 words
The method of claim 1, wherein said first layer contains a first abrasive and said second layer contains a second abrasive different from said first abrasive, said first layer being an upper layer and said second layer being a lower layer.
Claim 8
Dependent Claim
48 words
The method of claim 6, wherein said first abrasive is selected is selected from the group consisting of oxides, nitrides, and carbides of chromium, aluminum, titanium, and silicon, and said second abrasive is selected from the group consisting of oxides, nitrides, and carbides of chromium, titanium, and silicon.
Claim 9
Dependent Claim
31 words
The method of claim 7, wherein said first abrasive is present in an amount of 5% or less by weight of a total weight of magnetic material of said first layer.
Claim 10
Dependent Claim
31 words
The method of claim 7, wherein said first abrasive is present in an amount of 3% or less by weight of a total weight of magnetic material of said first layer.
Claim 11
Dependent Claim
42 words
The method of claim 7, wherein a thickness in μm of said first layer multiplied by an portion by weight in percent of said first abrasive relative to a total weight of magnetic material of said first layer is 0.5 or more.
Claim 12
Dependent Claim
17 words
The method of claim 1, wherein said first and second layers are made of different magnetic materials.
Claim 13
Dependent Claim
27 words
The method of claim 11, wherein said first layer contains barium ferrite and iron oxide, and said second layer contains a metal including nickel and iron oxide.
Claim 14
Dependent Claim
14 words
The method of claim 1, wherein said first and second layers contain different binders.
Claim 15
Dependent Claim
33 words
The method of claim 13, wherein said first layer contains nitrocellulose and urethane as a binder, and said second layer contains a copolymer of vinyl acetate, vinyl chloride and urethane as a binder.
Claim 16
Dependent Claim
20 words
The method of claim 1, wherein said measuring step comprises measuring the thicknesses separately of said first and second layers.
References Cited (Backward Citations)
No citation records indexed.
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