TLens® for Smartphones

Few industry segments are more competitive than the smartphone market. And not only is this segment competitive – it is also driven by technology speed and innovation. Most smartphone OEMs must balance cost and time to market (TTM) with product differentiation and innovation. poLight’s technology brings unique innovation opportunities to one of the most critical features of a mobile phone; the camera.

TLens in front-facing cameras

First, let’s look at the classic selfie. The user wants every person in the photo, as well as their background, to be rendered in focus. In this case, the ultra-quick TLens® captures 3 images with different focus. These images are stitched together into one, all-in-focus image, as illustrated below. The technology can also be used to create the opposite user experience, where only one part of the picture is in focus and the background is blurred, often called the “Bokeh” effect. The TLens enables the latter effect using a single camera.

polight use case single front

TLens in back cameras – all-in-focus

In the use case illustrated below, the photographer wants to capture an image with everything in focus, using the traditional back camera. As in the front-camera example, three or four images are captured over a very short time span, and are subsequently stitched together into one image with everything in focus.

polight use case single back

These examples illustrate just two of many unique use cases that the TLens technology can accommodate. There are various ways in which smartphone OEMs can implement the poLight products’ unique capabilities. These options span from simply adding a TLens on top of a fixed camera module, all the way to extensive design and application changes. poLight is ready to partner and support you in your design activities.

TLens vs VCM in smartphones

Illustrating the difference between TLens and VCM technology, the video below shows how TLens technology can advance the smartphone camera experience. On the left, TLens focuses extremely fast, and has no field-of-view variation. The example is shot with a mid-tier phone, with the TLens mounted on a fixed-focus camera, and using a contrast-based autofocus algorithm.

The video on the right was shot with a high-end smartphone that uses a VCM with PDAF. Notice that the focusing speed is significantly lower, that the camera is sometimes unable to focus, and that the use of VCM technology causes a “pumping” effect.

TLens for dual/multi-camera implementation

What can poLight® bring to a multi-camera device? TLens® Silver, the first poLight product launched, is based on a polymer lens that can be tuned by a piezo element. TLens Silver provides extremely fast focus, without the drawbacks of the VCM technology, and can therefore replace traditional VCM modules TLens also provides a range of other unique multi-camera features:

  • Constant field of view (FoV). This simplifies image alignment, stitching, and bracketing in a multi-image/multi-camera use case, i.e. where several images are stitched into one, to achieve All-in-Focus. Constant field of view solves the problem of “pumping” – image size variation when focusing – which all VCMs share, and which compromises the quality of images and videos, and could even cause queasiness during focusing. Constant field of view also minimises the processing power required to combine images.
  • Stable optical axis. The TLens technology provides superior image quality, as the optical axis remains unaffected by a changing focus, gravity (orientation of the phone), or shocks generated by unfortunate but probable drops during the phone’s life-time. Again, this is unique to the TLens technology and cannot be replicated by traditional VCMs.
  • Low power consumption. As consumers are using the camera more and more, this feature is key. TLens Silver consumes less than 5mW, which, compared with VCMs, is minuscule. This is especially important in multi-camera implementations, where energy efficiency is critical. While two TLenses will consume less than 10mW, two VCM modules can easily consume 400mW or more! The VCM module power consumption also creates heat, which may affect optical performance.
  • Smaller footprint. The TLens technology is extremely compact, and will not increase the width of the optical package, as no coils or motors are placed around the lens stack. This reduces the actual size of the camera modules, with one exception: If the TLens is added on top of a fixed camera, it will be positioned on top of the lens package, adding some tenths of a mm in height. If the TLens is fully integrated into the CM, however, the height increase can be cancelled out. The typical footprint of two TLens-equipped camera modules is half of that of two camera modules equipped with VCMs. The new package allows the front of the camera to be designed to save 1-2mm, which can be used for a bigger displays /Higher fill factor.
  • No magnetic interference. TLens Silver has no magnets, coils or springs. Magnetic interference is therefore negligible, and two autofocus cameras can be placed close to each other without interference. This provides OEMs with extensive design autonomy, and minimises interference with other coils and RF parts.
  • Simplified testing and calibration. Dual cameras have to be calibrated, which cannot be performed well with VCM cameras, since the parameters are changing. In contrast, a TLens dual-camera solution can easily be calibrated and optimised.

While these unique features are not restricted to dual-camera use cases, we draw attention to them in this context because they offset two major drawbacks otherwise associated with dual/multiple-camera technologies:

  • The TLens’ constant field of view, stable optical axis, and elimination of magnetic interference and influence of gravity, solves the image quality problem.
  • The TLens’ intrinsically low power consumption and reduced processing power requirement, as a result of constant field of view and the stable optical axis, solves the power consumption problem.