マシンビジョン用レンズのIP等級：IP67、IP68、IP69Kが実際に何を意味するのか

What Do the IP Rating Digits Actually Mean?

An IP code is two digits after the letters "IP," defined in IEC 60529, Degrees of Protection Provided by Enclosures. The first digit, 0 through 6, rates protection against solids: a 6 means dust-tight.

The second digit, 0 through 9, rates protection against liquids. A 7 means immersion in still water to 1 meter for 30 minutes. An 8 means immersion beyond that, at a depth and duration the manufacturer specifies. IP69K is defined separately, in ISO 20653, not IEC 60529: it sprays water at roughly 80°C and 80 to 100 bar from 100 to 150mm, at several angles. That is a directional high-pressure load, not slow immersion.

Because the tests load the seals differently, the two ratings are not points on one scale. An IP67 mark does not certify performance against a high-pressure jet, and an IP69K mark does not imply the 30-minute immersion test was run. Unless the datasheet shows both, assume only the one listed. Dual-rated IP67/IP69K parts, common in automotive, carry both marks for that reason.

Commonlands seals select M12 lens variants to IP67 and IP69K. The table below maps each ingress class to the deployment conditions it covers.

How Is an M12 Lens Barrel Sealed to Reach an IP Rating?

An M12 lens has three predictable entry points for dust and moisture in an unsealed design: the M12×0.5 thread interface where the barrel screws into the camera mount, the joints between internal barrel sections, and the retaining ring that holds the front element. A sealed variant closes each path mechanically rather than relying on the optics.

1. Thread interface O-ring. A rubber O-ring at the M12 thread, compressed when the lens is torqued into the mount, blocks the threads, the single largest gap in an unsealed design.
2. Sealed internal barrel joints. Where the barrel is assembled from multiple machined sections, adhesive or press-fit seals close the seams so moisture cannot migrate between elements internally.
3. 前玉の接着またはシール処理。ドライフィット式の着脱可能な保持リングの代わりに、前玉の表面を接着またはガスケットでシールし、最も露出している光学面を直接の水との接触から遮断しています。
4. Hydrophobic front coating (optional). A hydrophobic coating makes water bead and roll off the front element, reducing contamination and improving contrast in rain. It is a surface treatment, not an ingress seal, and does nothing for the thread or barrel joints.

Two mechanical facts follow. First, sealing is a manufacturing-time decision baked into a specific mechanical variant, which is why the same base SKU can ship in a sealed and an unsealed version. See why the same SKU can carry different ratings. Second, the seal is permanent once assembled: there is no field upgrade from unsealed to IP67, or from IP67 to IP69K, on an existing unit.

The step from IP67 to IP69K is not a stronger version of the same O-ring. A close-range directional jet can exploit a gap that slow immersion never loads hard enough to reveal. IP69K barrels use tighter O-ring compression and added sealing at the barrel-to-cap interface. A Commonlands automotive-grade variant such as the CIL190 adds an all-glass formula in an aluminum barrel rather than unfilled-plastic components.

Metal is favored here less for thermal expansion than for creep: an unfilled polymer barrel deforms slowly under sustained O-ring load at washdown temperature, relaxing the seal squeeze. Confirm barrel material and washdown qualification against the datasheet.

Does a Sealed Lens Replace an External Camera Housing?

カメラ本体の他の部分も同様に密閉されている場合に限ります。密閉型のレンズバレルは光路そのものを遮断しますが、レンズの後方にある基板、コネクタ、筐体は、それぞれ独自の侵入経路を持つ独立した機械システムです。密閉されていないカメラ本体にIP規格対応のレンズを装着しても、基板やコネクタのレベルではシステムが依然として外部にさらされたままとなります。

Two integration patterns are common. In the first, a sealed lens threads into a camera module whose board and connectors are also sealed to a matching rating, typical of compact automotive and robotics modules built as one unit. The sealed lens then removes the need for a separate housing and its protective window, along with the reflection loss that window adds.

In the second, an existing unsealed camera is retrofitted into an external IP-rated enclosure with a window in front of a standard lens. This works with any camera but adds weight, bulk, and a window to maintain. It is often the only option late in a project or when adapting an off-the-shelf camera that was never sealed. Specified early, a sealed lens against a sealed board is usually the lower total-system-cost path.

The table below weighs a sealed Commonlands M12 lens in a sealed module against a standard lens behind a housing window.

For background on M12 construction and mount standards, see what is an M12 lens. For environmental design beyond ingress (thermal stability, vibration resistance, and coatings), see ruggedized machine vision lenses. That page covers what this article does not.