Solid-State Relays and Contactors Patents: Top Companies & Trends 2026
- Concentrated at the top. The top 5 assignees account for 40 of 50 records in scope (80.0%), with a single leader holding 18.
- Filings have gone flat. Activity peaked at 8 filings in 2017 and had fallen to 0 by the midpoint year of 2022, with no clear recovery since.
- Nearly all claim traffic sits in one subclass. 94.0% of records carry an H01H switches-and-relays classification; measurement (G01R) and magnetics (H01F) trail well behind.
What this landscape covers
This dataset tracks patent activity at the intersection of solid-state relays, electromagnetic contactors and power switching relays, filtered to filings that address concrete failure and control problems: contact erosion, zero-cross switching, off-state leakage, DC breaking and coil drive. The scope spans publications from 2015 through the 2026-07-31 cut-off, drawing on 50 published records classified against H01H47, H03K17 and H01H50.
Because publication lags filing by roughly 18 months, the most recent year in the trend line understates real activity and should be read as a floor, not a ceiling. The technology classes below are counted per record, so a single filing that touches both switching contacts and measurement circuitry is counted in both — shares are given against the full 50-record base, not against each other.
Filing trend and classification mix
Two views of the same 50-record set: how filing activity has moved year over year, and which IPC subclasses carry the claim language.
A peak in 2017, then a decline to zero
Filings reached their high point at 8 in 2017. By 2022, the midpoint of the window, annual filings had dropped to 0, and the series shows no sustained rebound through the 2026 cut-off — bearing in mind that the final year or two is always undercounted due to publication lag.
One subclass dominates the claim space
H01H (switches and relays) appears on 94.0% of the 50 records, confirming this is squarely a switching-hardware corpus. G01R (electric and magnetic measurement) at 20.0% and H01F (magnets, inductors and transformers) at 12.0% point to secondary claim activity in sensing and coil components; H03K and the plastics-molding classes (B29C/B29K/B29L) each cover a handful of records and mark narrower, more specialized filings.
Shares are the percentage of the 50 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Solid-State Relays and Contactors with Eureka
This page is one run against one query. Ask Eureka your own question about solid-state relays and contactors and every answer comes back with the patent numbers behind it.
Try EurekaA representative filing and the most-cited prior art
Operation coil drive device for an electromagnetic contactor (EP3432334A1)
The filing describes a drive controller and current detector that infer whether a contactor's movable iron core has fully attracted, by monitoring coil current and adjusting the on/off time ratio of a semiconductor switching element — without a position sensor or timer.Filed by Fuji Electric FA Components & Systems; published 2019-01-23.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5539608A | Electronic interlock for electromagnetic contactor | 97 |
| 2 | US4603269A | Gated solid state FET relay | 80 |
| 3 | JP2004186052A | Coil drive circuit of electromagnetic contactor | 47 |
| 4 | GB2275541A | Electromagnetic contactor | 31 |
| 5 | US5204633A | Electromagnetic contactor with closure fault indicator | 29 |
| 6 | US20130301181A1 | Electromagnetic contactor | 17 |
| 7 | JP2009009813A | Electromagnetic contactor | 15 |
| 8 | US20180218862A1 | Operation coil drive device of electromagnetic contactor | 14 |
| 9 | WO2017159070A1 | Operation coil drive device for electromagnetic contactor | 14 |
| 10 | CN107924787A | 电磁接触器的操作线圈驱动装置 | 14 |
Citation counts reflect influence within the searched corpus and skew toward older filings; treat them as a signal of prior-art weight, not of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once the ranking, the trend line and the classification mix are read together.
A small group controls most of the claim space
Forty of the 50 records in scope belong to the five leading assignees, with the single leader alone accounting for 18. That leaves a short tail: by the tenth-ranked assignee, cumulative share reaches 98.0% of all records, meaning the remaining companies each hold only one or two filings.
Activity has cooled rather than accelerated
The series peaked at 8 filings in 2017 and had fallen to 0 by 2022. None of the leading assignees show filings in the latest tracked year, which is consistent with either a mature, well-occupied claim space or a segment where R&D has shifted toward adjacent control electronics not captured by this search string.
Switching hardware, not sensing, is the center of gravity
Nearly all records sit in H01H (switches and relays), with measurement (G01R, 20.0%) and magnetics (H01F, 12.0%) appearing as secondary themes rather than standalone clusters. The smaller classes — H03K, and the plastics-molding trio B29C/B29K/B29L — mark isolated, narrowly scoped filings rather than emerging sub-fields.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to solid-state relays and contactors, with the prior art for and against each one.
Who holds the claim space, and where the gaps sit
The ranking covers 16 companies total, drawn from the full assignee list the data endpoint returns for this search — not a curated top-50 or top-100.
One company holds more than a third of the corpus alone
The leading assignee's 18 records already exceed the combined total of every company ranked sixth or lower, a strong signal that coil-drive and contact-erosion claim language in this space is heavily pre-occupied by one filer's portfolio.
Most ranked companies hold only a handful of filings
Beyond the top 10 combined (98.0% of all 50 records), the remaining ranked companies contribute the last 2.0% between them — evidence of a field where entry has been possible but sustained portfolios are rare.
Co-filing is limited and mostly internal
The strongest co-assignee pair links two entities within the same corporate family, filing together on 5 records; the next strongest pairs, each appearing twice, connect named inventors rather than separate companies. Cross-company joint filing is effectively absent from this corpus.
| Assignee | Recent year | YoY |
|---|---|---|
| Fuji Electric FA Components & Systems Co., Ltd. | 0 | — |
| Mitsubishi Electric Corporation | 0 | — |
| Westinghouse Electric Corporation | 0 | — |
| Fuji Electric Co., Ltd. | 0 | — |
| Larsen & Toubro Limited | 0 | — |
| International Business Machines Corporation | 0 | — |
| TAKAYA KOUETABU | 0 | — |
| TAGUCHI TAKAHIRO | 0 | — |
Where to take this analysis
The dataset points to a concentrated, slowing field with a dominant leader and a thin long tail — the next step is testing specific claim language against that backdrop.
Check freedom-to-operate against the leader's portfolio
With one assignee holding 18 of 50 records, any new filing on coil drive or contact-erosion detection should be checked against that portfolio specifically, not just the field average.
Explore assignee portfolios in EurekaTest claims in the under-claimed branches
Zero-cross switching, sensorless coil-drive detection and off-state leakage sensing carry far fewer filings than core H01H switching claims and are worth a focused search before drafting.
Run a white space search in EurekaWatch for a filing rebound
Filings fell to zero by the midpoint year with no rebound visible yet, but the last one to two years are undercounted due to publication lag — worth re-checking this trend in future updates.
Track filing trends in EurekaCommon questions about this landscape
The ranked assignee list for this search covers 16 companies, and it is heavily concentrated: the top five together hold 40 of the 50 records in scope, or 80.0%, and the single leading assignee alone accounts for 18. By the tenth-ranked company, cumulative share reaches 98.0%, so the remaining companies in the ranking each hold only one or two filings. Anyone evaluating freedom to operate in this space should focus first on the leader's portfolio rather than treating the field as evenly spread.
Based on this dataset, filing activity has slowed rather than grown. The peak year was 2017 with 8 filings, and by the 2022 midpoint annual filings had dropped to 0, a pattern that continues through the most recent tracked years. Because publication typically lags filing by around 18 months, the last year or two in any trend line is undercounted, so a genuine rebound in very recent filings would not yet be fully visible in this data.
The corpus is dominated by core switching hardware: 94.0% of the 50 records carry an H01H classification, covering switches and relays broadly. Secondary themes include electric and magnetic measurement (G01R, 20.0% of records) and magnetics such as inductors and transformers (H01F, 12.0%), while pulse-technique circuits (H03K) and plastics-molding classes appear on only one or two records each. This means most claim activity centers on the switching mechanism itself rather than on sensing or packaging.
EP3432334A1, filed by Fuji Electric FA Components & Systems and published in 2019, describes an operation coil drive device for an electromagnetic contactor that detects whether the movable iron core has fully attracted by monitoring coil current, rather than by using a physical position sensor or a timer. The drive controller adjusts the on/off time ratio of a semiconductor switching element based on that current reading. This is relevant because sensorless attraction detection is a specific, narrow technical route within the broader coil-drive space, and anyone designing a similar current-sensing drive circuit should review its claim scope directly.
The classification data suggests the core H01H switching claims are heavily occupied, but adjacent branches carry far fewer records: zero-cross switching control, off-state leakage sensing that overlaps with G01R measurement classes, and sensorless coil-drive detection methods all appear less frequently in this corpus. Plastics-molding aspects of contactor housings (B29C, B29K, B29L) also show only one record each. These lower-density branches are reasonable starting points for a novelty search, though a full clearance check against the leading assignee's portfolio is still necessary before drafting.
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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.