US5952953A
Expired / Lapsed
US
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Wave absorber
Assignee: Maxell Ltd
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Filing: 1998-03-13
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Granted: 1999-09-14
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Expires: 2018-03-13
Abstract
Abstract A wave absorber which is light in weight, rich in flexibility and excellent in wave absorption characteristics in a microwave frequency range. The wave absorber in which composite carbon black particles including crystalline graphite and amorphous carbon black are dispersed into an insulating matrix. In the wave absorber, dispersion of the composite carbon black particles is adjusted so that a ratio ( rho /R) of a volume resistivity rho measured at frequencies of 30, 100 and 500 kHz to a measured DC volume resistivity R is in a predetermined range and a volume ratio of the composite carbon black particles having particle diameters of 10 nm to 200 nm to all the composite carbon black particles is in a range of 5% to 95%. Thereby, a wave absorber excellent in absorption characteristics is obtained.
Inventors
- 👤 Yoshio Nikawa
- 👤 Masaru Chino
- 👤 Shinichi Kitahata
- 👤 Keiko Kurata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:12
CPC Classifications
H; H01; H01Q; H01Q17/00; H01Q17/007; H01Q17/004
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
69 words
A wave absorber in which composite carbon black particles including crystalline graphite and amorphous carbon black are dispersed into an insulating matrix, wherein a measured DC volume resistivity is in a range of 1×10 2 Ω·cm to 1×10 5 Ω·cm and a ratio (ρ 30 /R) of a volume resistivity ρ 30 measured at a frequency of 30 kHz to R is in a range of 0.2 to 0.8.
Claim 2
Dependent Claim
69 words
A wave absorber in which composite carbon black particles including crystalline graphite and amorphous carbon black are dispersed into an insulating matrix, wherein a measured DC volume resistivity is in a range of 1×10 2 Ω·cm to 1×10 5 Ω·cm and a ratio (ρ 30 /R) of a volume resistivity ρ 30 measured at a frequency of 30 kHz to R is in a range of 0.2 to 0.8.
Claim 3
Dependent Claim
69 words
A wave absorber in which composite carbon black particles including crystalline graphite and amorphous carbon black are dispersed into an insulating matrix, wherein a measured DC volume resistivity is in a range of 1×10 2 Ω·cm to 1×10 5 Ω·cm and a ratio (ρ 100 /R) of a volume resistivity ρ 100 measured at a frequency of 100 kHz to R is in a range of 0.05 to 0.4.
Claim 4
Dependent Claim
69 words
A wave absorber in which composite carbon black particles including crystalline graphite and amorphous carbon black are dispersed into an insulating matrix, wherein a measured DC volume resistivity is in a range of 1×10 2 Ω·cm to 1×10 5 Ω·cm and a ratio (ρ 100 /R) of a volume resistivity ρ 100 measured at a frequency of 100 kHz to R is in a range of 0.05 to 0.4.
Claim 5
Dependent Claim
69 words
A wave absorber in which composite carbon black particles including crystalline graphite and amorphous carbon black are dispersed into an insulating matrix, wherein a measured DC volume resistivity is in a range of 1×10 2 Ω·cm to 1×10 5 Ω·cm and a ratio (ρ 500 /R) of a volume resistivity ρ 500 measured at a frequency of 100 kHz to R is in a range of 0.03 to 0.3.
Claim 6
Dependent Claim
69 words
A wave absorber in which composite carbon black particles including crystalline graphite and amorphous carbon black are dispersed into an insulating matrix, wherein a measured DC volume resistivity is in a range of 1×10 2 Ω·cm to 1×10 5 Ω·cm and a ratio (ρ 500 /R) of a volume resistivity ρ 500 measured at a frequency of 100 kHz to R is in a range of 0.03 to 0.3.
Claim 7
Dependent Claim
68 words
A wave absorber as set forth in claim 1, 2 or 3, wherein said composite carbon black particles have particle diameters of 10 nm to 10 μm and a volume ratio of the composite carbon black particles having particle diameters of 10 nm to 200 nm measured by an X-ray small-angle scattering method to all the composite carbon black particles is in a range of 5 to 95%.
Claim 8
Dependent Claim
58 words
A wave absorber as set forth in claims 1, 2 or 3, wherein said composite carbon black particles have a graphite formation proportion of from 10% to 70% found from a peak area ratio of (002) plane in an X-ray diffraction method and said insulating matrix contains 2 to 20 weight % of said composite carbon black particles.
Claim 9
Dependent Claim
55 words
A wave absorber as set forth in claim 4 wherein said composite carbon black particles have a graphite formation proportion of from 10% to 70% found from a peak area ratio of (002) plane in an X-ray diffraction method and said insulating matrix contains 2 to 20 weight % of said composite carbon black particles.
References Cited (Backward Citations)
US3568195A
Cited
US3721982A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-09-13 | 2003-03-15 | 2003-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-13 | 2007-03-15 | 2007-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-13 | 2011-03-15 | 2011-09-14 | $7700.00 | Window Closed / Lapsed |