Thyristor Patents: Top Companies & Filing Trends 2026
- Concentrated at the top. The five leading assignees hold 611 of 1,214 records in scope (50.3%), and the leading ten hold 772 (63.6%) — a small group controls most of the documented claim space.
- Filing has flattened, not grown. Annual filings rose from 8 in 2017 to a peak of 25 in 2021, then fell back toward the 2022 midpoint of 7 — the field is not expanding at the rate the peak year suggests.
- Japan dominates the receiving-office mix. 575 of the tracked filings were received in Japan, more than double the 266 in the United States and far ahead of the 139 filed at the EPO.
What this landscape covers
This landscape tracks 1,214 published records at the intersection of thyristor, silicon-controlled-rectifier and power-rectifier-device claims with specific technical limitations — surge current capability, turn-off time, press-pack housing, HVDC valve application and dv/dt withstand — inside IPC classes covering semiconductor devices and power conversion. It spans filings from 2015 through the mid-2026 data cut-off, so the most recent year is necessarily undercounted: publication typically lags filing by around eighteen months.
The scope favours devices engineered for high-voltage, high-current switching duty rather than small-signal or logic-level parts, which is why power conversion and protective-circuit classes sit alongside the core semiconductor-device classification.
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Filing trend and technology composition
Two views of the same 1,214 records: the year-by-year filing count, and how those records distribute across IPC subclasses. Because a single record can carry several IPC codes, the class shares below sum to more than 100% of the record total — that is expected and is not a data error.
A peak in 2021, then a pullback
Annual filings climbed from 8 in 2017 to a peak of 25 in 2021, then eased back toward the 2022 midpoint of 7. Read the tail end of the chart cautiously: the 2026 count of 1 reflects the partial year and publication lag, not a sudden stop in activity.
Semiconductor-device claims dominate, power conversion is the strongest secondary class
H01L (semiconductor devices) appears in 884 of the 1,214 records in scope (72.8%), far ahead of H02M (power conversion, 365 records, 30.1%). Pulse-technique claims under H03K (112 records, 9.2%) and protective-circuit claims under H02H (33 records, 2.7%) sit well behind, marking areas of comparatively thin coverage relative to the device-structure core.
Shares are the percentage of the 1,214 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Thyristors and Power Rectifier Devices with Eureka
This page is one run against one query. Ask Eureka your own question about thyristors and power rectifier devices and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited and most representative filings
US4281336A — Thyristor element with short turn-off time and method for producing such element
A fast switching thyristor uses a shorted-emitter structure where charge-carrier lifetime is deliberately lowered via recombination centers to shorten turn-off time. The control base zone lifetime is set homogeneously low to match a target firing resistance beneath the emitter zone, with a further-reduced lifetime in the partial region beneath the control electrode, targeting fast recovery without sacrificing forward-voltage stability.Filed by Licentia Patent-Verwaltungs-G.m.b.H., granted 1981-07-28 — one of the earliest structural approaches to turn-off time reduction still cited across this landscape.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4060757A | Inverters having a transformer-coupled commutating circuit | 254 |
| 2 | US4151387A | Metal base cookware induction heating apparatus having improved power control circuit for insuring safe opera… | 148 |
| 3 | US3710062A | Metal base cookware induction heating apparatus having improved power supply and gating control circuit using… | 130 |
| 4 | US5369291A | Voltage controlled thyristor | 110 |
| 5 | US20030183838A1 | Solid-state DC circuit breaker | 101 |
| 6 | US4078247A | Inverter circuit control circuit for precluding simultaneous conduction of thyristors | 90 |
| 7 | US5489787A | Semiconductor device having an insulated gate field effect transistor and exhibiting thyristor action | 89 |
| 8 | US6084253A | Low voltage four-layer device with offset buried region | 81 |
| 9 | US3953783A | Low cast chopper inverter power supply and gating circuit therefor | 71 |
| 10 | US6054728A | Insulated gate thyristor | 59 |
Citation counts inside this corpus skew toward older filings simply because they have had longer to accumulate citations — treat them as a signal of influence on later work, not as a measure of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for filing strategy
The concentration, technology mix and geography together point to a mature but narrowly held field where the core device structure is heavily claimed and the surrounding control and protection circuitry is comparatively open.
A small group controls the core claim space
Five assignees hold 611 of the 1,214 records in scope, and the leading ten extend that to 772 records (63.6%). New entrants are filing into device-structure territory that a handful of established electrical-equipment makers have already occupied for decades.
Growth peaked mid-decade and has not been sustained
Filings rose from 8 in 2017 to a peak of 25 in 2021, then fell back toward the 2022 midpoint of 7. That pattern reads as a field responding to a specific demand cycle — likely HVDC and grid-scale power-conversion investment — rather than one on a sustained growth trajectory.
Device structure dominates; control circuitry is thinner
H01L claims appear in 884 of 1,214 records, more than double the 365 records touching H02M power-conversion claims. Protective-circuit claims (H02H, 33 records) and motor/generator control claims (H02P, 35 records) are present but far less contested.
Japan anchors the filing base, the US and Europe trail
Japan's receiving-office count of 575 is more than double the 266 filed in the United States and well ahead of the 139 filed at the EPO. Any freedom-to-operate check on device-structure claims should start with Japanese-office filings before extending to US or European counterparts.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to thyristors and power rectifier devices, with the prior art for and against each one.
Who holds the ground, and where filing has gone quiet
The ranked leaders are longstanding electrical-equipment and semiconductor manufacturers rather than recent entrants, and recent-year momentum data suggests filing activity from the largest historical assignees has slowed markedly.
One assignee holds nearly a third of the top-5 total
The leading assignee's 176 records sit well ahead of the fifth-place holder's 69, showing a steep drop-off even within the top tier rather than a smooth gradient.
The drop from top 5 to top 10 is steep
Combined records held by the leading ten reach 772 (63.6% of all 1,214 records), but the 10th-place assignee alone holds only 28 — most of that combined share is still concentrated in the top few positions.
Recent-year filing from historical leaders has gone quiet
Recent-year momentum figures show the tracked legacy assignees registering zero filings in the latest year. Combined with the post-2021 pullback in overall filings, this points to a field where the incumbents' claim positions are largely locked in rather than actively expanding.
| Assignee | Recent year | YoY |
|---|---|---|
| Mitsubishi Electric Corp | 0 | — |
| Toshiba Corp | 0 | — |
| Fuji Electric Co., Ltd. | 0 | — |
| Hitachi, Ltd. | 0 | — |
| Meidensha Corp | 0 | — |
| Siemens AG | 0 | — |
| General Electric Co | 0 | — |
| Westinghouse Electric Corp | 0 | — |
Turning this landscape into a filing decision
The dataset shows where claim density sits and where it thins out; the next step is testing a specific claim idea against that landscape rather than reading the field in the abstract.
Check freedom-to-operate against the top holders
Before drafting around device-structure improvements, run a targeted search against the leading assignees' portfolios — the top 5 alone hold half of all records in scope, so structural claims are the most crowded starting point.
Run a freedom-to-operate check in EurekaDraft into the thinner protective-circuit branches
H02H protective-circuit claims and H02P motor-control claims carry far fewer records than the H01L device-structure core, suggesting more room to stake a defensible first claim there.
Explore white space in EurekaTrack whether the 2021 peak was a one-off cycle
Filings fell from a 2021 peak of 25 back toward single digits; watching whether that recovers alongside HVDC and grid investment cycles will tell you whether this is a rebound field or a maturing one.
Set up trend monitoring in EurekaCommon questions about thyristor and power rectifier patents
The ranking is concentrated at the top: the leading assignee alone holds 176 of the 1,214 records in scope, and the top five combined hold 611 records (50.3% of all records in scope). The top ten extend that to 772 records, or 63.6% of the field. These are longstanding electrical-equipment and semiconductor manufacturers rather than recent entrants, which means most of the core device-structure claim space has been staked out for years.
No — filing activity peaked in 2021 at 25 records and has since fallen back toward the levels seen around the 2022 midpoint of 7 per year. Filings started at 8 in 2017, so the field grew for several years before pulling back. Recent-year data also shows zero filings in the latest year from every one of the tracked legacy leaders, reinforcing that the recent trend is a slowdown rather than a plateau at a high level.
H01L, the core semiconductor-devices class, appears in 884 of the 1,214 records in scope (72.8%), making it by far the densest classification. H02M, covering power conversion circuitry such as AC/DC conversion, follows at 365 records (30.1%). Because a single filing can carry multiple IPC codes, these percentages add up to more than 100% of the record total — that is expected and reflects overlapping classification rather than double-counting of distinct filings.
US4281336A, granted to Licentia Patent-Verwaltungs-G.m.b.H. in 1981, claims a shorted-emitter thyristor structure that lowers charge-carrier lifetime via recombination centers to shorten turn-off time, with a specific lifetime gradient between the control base zone and the region beneath the control electrode. It is a structural approach to fast turn-off rather than a control-circuit or packaging claim, so it constrains device-structure designs using that particular lifetime-gradient technique specifically, not turn-off-time improvement generally. Anyone designing a fast-turn-off thyristor should check this filing's claim scope alongside more recent structural filings from the top-ranked assignees before finalising a device architecture.
Protective-circuit claims under H02H appear in only 33 of the 1,214 records (2.7%), and motor/generator control claims under H02P appear in 35 records (2.9%) — both far behind the 884-record H01L core. Sub-areas tied to press-pack housing thermal design, dv/dt withstand circuit topology, and solid-state DC circuit breaker integration also sit outside the densest classes. These are reasonable starting points for a freedom-to-operate check, though a thinner class count is not proof of an empty field and should be verified against the specific assignees active there.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.