How e-con Systems’ M12 VCM Module Equips Autofocus Cameras with Multiple Lenses

Traditional autofocus (AF) camera modules – often built in M6 or M7 form factors – typically use fixed, built-in lenses that cannot be changed. These modules have a predetermined field of view (FoV) based on the fixed lens, with no interchangeable lens option​s. It means if a different FoV or focal length is required, one must use a new camera module or customize the existing module. Such customization can incur high non-recurring engineering charges for the design and development.​

Hence, fixed-lens AF modules lack flexibility. Developers can get locked into a single lens and FoV or face major engineering efforts to change it. To overcome these limitations, e-con Systems has introduced an M12 VCM autofocus module as a solution. This module supports the standard M12 (S-mount) lens interface, making it easy to use interchangeable lenses while providing autofocus capability.

In this blog, you’ll learn about how e-con Systems’ M12 VCM autofocus module works and its various advantages.

What is e-con Systems’ M12 VCM module?

M12 (also known as S-mount) is a standard screw-thread lens mount commonly used in board-level cameras.​ A Voice Coil Motor (VCM) uses a magnetic field to move a coil back and forth. In a camera lens, VCM is used to adjust the position of the lens elements, enabling autofocus capabilities.

e-con Systems’ M12 VCM module integrates a VCM with an M12 lens mount. The voice coil motor mechanism moves the lens mount in and out to adjust focus, equipping developers to swap in different M12 lenses while maintaining full autofocus.​

How Autofocus Capabilities Work with VCM

Autofocus is a feature in cameras and imaging devices that automatically adjusts the lens to bring a subject into sharp focus. The system continually adjusts the lens until the image is sharp. The typical autofocus workflow is as follows:

• Measuring the subject distance or focus error: The camera’s processor (or ISP – Image Signal Processor) evaluates the scene to determine if the subject is in focus and, if not, how far off the focus is. This can be done using contrast detection (maximizing image sharpness) or phase detection sensors on the camera sensor. Essentially, the autofocus algorithm measures the distance or focus discrepancy between the lens’s current position and the ideal focus position.​
• Moving the lens for focus adjustment: Based on the focus error measurement, the system issues a command to adjust focus. By changing the lens position, the camera shifts the focal plane to converge on the subject at the measured distance.​
• Processing image/ISP algorithm: After the lens moves, the ISP or focus control algorithm analyzes the new image to check if the focus has improved. The ISP continuously processes image sharpness or phase information to decide if further adjustment is needed.
• Controlling the VCM module: This driver supplies current to the voice coil motor. Increasing or reversing the current moves the lens forward or backward. A dedicated driver typically controls the coil current to achieve the target focus position.​

Through these steps, the M12 VCM module can automatically focus the image. All of this happens in fractions of a second!

Types of M12 VCM Modules

When using an M12 VCM module, one consideration is choosing the appropriate module height to match the lens’s optical requirements. e-con Systems offers the module in two height variants:

• 12 mm
• 8 mm

The 12 mm height module offers a taller lens holder, which provides a longer distance between the sensor and the lens mount. The 8 mm height module has a shorter lens holder, placing the lens closer to the sensor.

However, these heights may vary depending on the vendor. In practice, the selection between an 8 mm module vs. a 12 mm module will depend on the required flange focal length. This flexibility in physical configuration is another advantage of the M12 VCM approach, as it can support a wide variety of lenses with simple mechanical adjustments.

Advantages of e-con Systems’ M12 VCM Module

Multiple focal lengths with one camera

The module is highly flexible to use any M12 lens​, as developers can swap lenses to change the field of view or depth characteristics without changing the camera board or sensor. It means a single camera design can cater to various use cases, reducing development efforts since there’s no requirement for separate camera modules for each FOV requirement.

No need for manual lens calibration

Conventionally, changing lenses requires manual calibration to ensure the image remains in focus across the frame. This process involves fine-tuning the lens position and locking it in place, which can be time-consuming. However, with M12-based VCM modules, this manual calibration step is eliminated.

Reduced development and customization cost

As mentioned earlier, any compatible M12 lens can be supported by the module (with minimal effort)​. It accelerates development cycles and allows more off-the-shelf components in the design. This modular approach also lowers the barrier to offering customized FoVs.

e-con Systems’ M12-based VCM module

e-con Systems has been designing, developing, and manufacturing OEM cameras since 2003. Our M12-based VCM module is currently supported by See3CAM_CU135 (customized board) – a 4K USB camera based on a 1/3.2″ AR1335 CMOS image sensor. It also comes with advanced 1.1μm pixel BSI technology from onsemi®, offering great low-light performance and iHDR support.

Explore our Camera Selector Page to see our full portfolio.

If you need help finding the perfect camera solution for your embedded vision application, please write to camerasolutions@e-consystems.com.