Overview

The MEMS scanning projection technique is fundamentally different from the so-called matrix-based displays (LCD, LCOS or DLP). Matrix-based displays use a large matrix of millions of individual pixels to project images sequentially.

For consumer applications, key parameters for successful adoption of miniature and portable microprojectors are:

- Energy efficiency : projector brightness versus power consumption (battery life)
- Size and weight : easily portable
- Image quality and color gamut

1. High brightness

Lemoptix projectors have the possibility to use RGB laser light soures instead of UHL or LED. This is due to the use of continuously scanning MEMS scanning mirrors instead of a matrix-based projection system.

A major benefit of using laser light sources is the large energy provided in a short spectral bandwidth.

Key end-user benefit:

Better visual experience under all light conditions

2. Miniature

The projector thickness can be brought down to the millimeter range, as the thickness is directly related to the MEMS mirror dimensions.

Scaling of the MEMS-scanning projection system can be easily achieved due to its single light beam projection working principle. Matrix-display systems are limited by their inherent architecture and cannot scale without decreasing the amount of pixels, and consuquently a noticeable degradation of the image quality.

Key end-user benefit:

Miniaturization enables embedding the projector directly within mobile and industrial devices, eliminating the need for stand-alone accessory projectors

3. Always in focus

Due to the use of collimated laser light sources, the "flying spot" and consequently the projected pixel, have the same size whether the image is projected from a few cm or few meters. This means that the projected image is always in focus, even when projected on curved surfaces.

Unlike for matrix-based projectors, Lemoptix microprojectors do not require the use of complex optical components for manual or automatic focusing.

Key end-user benefit:

The MEMS microprojector image is always-in-focus, therefore no manual operation is required on these devices, which is ideal for portable devices.

4. Energy efficient

MEMS scanning projectors are highly energy efficient for three main reasons:

• The laser light beam, with its small spot size, hits the mirror surface entirely, therefore avoiding any light loss typically seen in systems using omni-directionnal light sources.
• The mirror is coated with highly reflective coating material, reflecting above 90% of the incoming light.
• No light loss occurs, as no intermediate optics are needed, as opposed to matrix-based projectors that require illumination optics, projection optics, polarizers, filters..

LCD UHPlamp-based projector; DLP LED-based projector

Key end-user benefit:

Power savings increasing battery life and providing a longer projection time.

5. Low cost

The manufacturing cost of projection systems depends on the number of elements (projection engine, optics...), the scaling of each component, the  complexity of the assembly processes, the optical alignement precision and the manufacturing yield.

In this respect, the Lemoptix MEMS scanning projector system has been developed to provide maximum performance at low-cost. They are consequently ideal for consumer applications where these features are esential.

• Number of elements: MEMS scanning projectors have the lowest number of elements compared to any other projection system
• Components scaling: MEMS mirror devices are small and highly scalable, compared to matrix-based projectors (in the semi-conductor industry, the chip price is directly related to the used silicon surface)
• Assembly complexity: In projection systems, the level of complexity of the assembly process (e.g. number of elements) determines the major portion of the final cost. The use of the fully and hermetically packaged MEMS mirrors from Lemoptix is therefore a key contributor to the simplification of the asembly process, whilst highly impacting the manufacturing yield
• Component alignment accuracy: All projection systems are very sensitive to optical alignment accuracy, leading to projection degradation and un-wanted optical distortion. Lemoptix has developed unique assembly technique to avoid the need for the so-called "dynamic alignment" method, where each component is placed and aligned indivudually during the ON-state of the system. As a result, Lemoptix's projector benefits from a considerably simplified assembly process, generating a high manufacturing yield.

Key end-user benefits:
Lower device price

6. Image quality

The Matrix-based projector image quality depends on the number of pixels on the core projection chip, which is directly related to the size of the matrix itself and consequently to the projector size. This implies that efforts to increase image quality conflict with projector scaling.

The MEMS-scanning projector image quality is dependent on a few factors that can be scaled over time^, i.e. the MEMS mirror scanning speed and angle, and the laser spot size. Indeed, a larger mirror scanning angle results in the possibility to add more pixels on the new coverage area and a smaller laser spot size induces the possibility to increase the pixel count on a given area.

Key user benefit:

Small size projector with high image quality

7. Vibrant colors

Due to the unique properties of the laser light sources, unprecedented colour gamut can be achieved.

Key end-user benefit:

Intense and vibrant colours, matching even closer the full colour gamut visible to the human eye.