Sound output device, earphone, hearing aid, and mobile terminal device
US-2020366996-A1 · Nov 19, 2020 · US
Air gaps using a magnetic fluid
Air gaps using a magnetic fluid · Cooperative Patent Classification (CPC)
Electric circuits, power, telecommunications, and semiconductors.
Related technology areas
Mapped technology topics for this CPC code.
| Metric | Value |
|---|---|
| CPC code | H04R9/027 |
| Official title | {Air gaps using a magnetic fluid} |
| Display label | Air gaps using a magnetic fluid |
| Total patents | 179 |
Filing trend
Year-over-year patent counts classified under this CPC code.
Filing activity over the last five years is stable.
| Year | Patents |
|---|---|
| 2015 | 16 |
| 2016 | 14 |
| 2017 | 7 |
| 2018 | 4 |
| 2019 | 5 |
| 2020 | 19 |
| 2021 | 13 |
| 2022 | 24 |
| 2023 | 35 |
| 2024 | 23 |
| 2025 | 15 |
| 2026 | 4 |
Representative patents
Representative publications under this CPC code from precomputed stats, or recent filings when stats are unavailable.
Speaker
US-10820115-B2 · Oct 27, 2020 · US
Display device
US-2020296496-A1 · Sep 17, 2020 · US
Receiver assembly comprising an armature and a diaphragm
US-10721566-B2 · Jul 21, 2020 · US
Electroacoustic transducer
US-2020228900-A1 · Jul 16, 2020 · US
Speaker
US-2020213750-A1 · Jul 2, 2020 · US
Loudspeaker and acoustic device
US-2020213785-A1 · Jul 2, 2020 · US
Speaker
US-2020213762-A1 · Jul 2, 2020 · US
Speaker
US-10674279-B1 · Jun 2, 2020 · US
Force cancelling transducer
US-10631096-B1 · Apr 21, 2020 · US
Inverted motor transducer with front spider
US-2020092654-A1 · Mar 19, 2020 · US
Speaker
US-2020045471-A1 · Feb 6, 2020 · US
Speaker
US-2020045472-A1 · Feb 6, 2020 · US
Speaker
US-2020045468-A1 · Feb 6, 2020 · US
System with thermoelectric conversion device
US-2019349690-A1 · Nov 14, 2019 · US
Hybrid Actuator
US-2019334076-A1 · Oct 31, 2019 · US
Vibration actuator
US-10406559-B2 · Sep 10, 2019 · US
Vibration actuator
US-2019091725-A1 · Mar 28, 2019 · US
Bone conduction device including a balanced electromagnetic actuator having radial and axial air gaps
US-10178484-B2 · Jan 8, 2019 · US
Receiver assembly comprising an armature and a diaphragm
US-2018367916-A1 · Dec 20, 2018 · US
Frequently asked questions
Answers are generated from the same data shown on this page.
- What is CPC H04R9/027?
- CPC H04R9/027 is the Cooperative Patent Classification code for “Air gaps using a magnetic fluid.”
- How many patents are filed under CPC H04R9/027 (Air gaps using a magnetic fluid)?
- Our database includes 179 publications tagged with this CPC code.
- Is patent activity under CPC H04R9/027 growing?
- Publication counts under this code: 23 in 2024 vs 15 in 2025 (latest complete years).