Concave lens in the design of LED microarray projection system

◢Projection System

In order to meet the market demand for portable projectors, a projection system based on LED micro arrays was designed. The system consists of a display unit and a projection objective, in which the projection objective includes a Plano-Concave Lens and aDouble-Concave Lenses produced and sold by our company. The projection objective lens adopts an anti-telephoto optical structure with a full-field view of 80° focal length of 8mm, which is a strong light and wide-angle lens. The projection system has the advantages of small size, simple structure and good projection effect.

Projection display refers to the technology of generating image information from the driving circuit and then amplifying and displaying it on the projection screen through the optical system and projection space. Projection technology has undergone three generations of change. The first generation of projection technology uses a cathode ray tube as the imaging device, and the phosphor inside the device is amplified and converged by the light-emitting system under high pressure to display a color image on the screen. The second generation of projection technology uses liquid crystal light plate for image modulation, and the image is transmitted and displayed by the projection system. With the increase of people's requirements for product comfort, the projection technology has been developed to high brightness, high quality and micro-miniature on the basis of the second generation technology. Among them, micro projector is the main development direction of the third generation projector, which has the characteristics of small size, large display size and high light energy utilization. The structure of this micro projector is mostly composed of Backlight Unit (BLU), color wheel, display unit, color prism, reflector, projection lens, etc. BLU is often a light emitting diode (LightE mitting Diode, LED).

With the development of technology, Micro-LEDs have attracted attention, which is a kind of high-density tiny size LEDs that can actively emit light.Micro-LEDs have the advantages of low operating voltage, high luminous efficiency, fast response time, compact structure, high resolution, and their light-emitting unit size can be controlled to the micron level, which can meet the requirements of high-resolution display. The applications of Micro LEDs cover a wide range of fields from display, medical, biological to military, communication, detection, etc.

◢Micro-LEDs

Based on the excellent optical properties of Micro-LEDs, this paper designs a two-dimensional array of Micro-LEDs, a self-luminous microdisplay device with high luminous brightness, as the display source in a projection system. A micro LED array projection system is designed. In the design, the number of optical elements, the size of the elements, and the size of the projection system are determined according to the application requirements. The number of optical elements, the size of the elements, and the complexity of the optical path are optimized according to the application requirements. The number of optical elements, the size of the elements, and the complexity of the optical path are optimized according to the application requirements so that the light energy utilization efficiency of the system is not affected The design is based on the application requirements, the number of optical elements, the size of the elements and the complexity of the optical path are optimized so that the miniaturization requirements can be achieved without compromising the efficiency of light utilization and effective stray light suppression. This projection system has the good image quality and can be widely used in home theater, car projection, portable projection, augmented reality, virtual The projection system has good image quality and can be widely used in home theater, car projection, portable projection, augmented reality, virtual reality, etc.

1.System structure and working principle

As shown in the figure, the micro projection system consists of 3 parts, including 3 monochromatic Micro-LEDs arrays, projection objectives (color combining prisms and relay imaging mirrors) and a receiving screen. The driver circuit controls the 3 monochrome Micro-LEDs arrays for image display, the color prism for color-light synthesis, and the projection objective for amplification of the emitted light, which is finally imaged on the receiving screen. The projection objective, as the terminal of the system, has an important impact on the imaging quality and color reproduction of the projector, so the design and optimization of the projection lens should be considered.

2.Projection Objective Lens

The projection objective is composed of a combined color prism and a relay imaging mirror set, and the design is optimized by treating the combined color prism as a parallel plate with the relay imaging mirror set. The projection system is shown in Fig. The size of the micro-LEDs array and the single pixel size determine the image field of view and the image resolution, respectively. The system performs color light synthesis by means of a color-combining prism, and each light from the projection surface contains R, G, and B color components.

3.Projection system structure

The function of the projection system is to restore the image on the microdisplay array realistically and project a large area, high imaging quality and good color reproduction on the projection screen. Therefore, this objective lens has the optical characteristics of short focal length, large relative aperture and large field of view. The projection objective lens is designed in the reverse way, because the light is projected nearly perpendicular to the image surface, and there is a projection objective lens, the lens needs to retain a certain distance after the work, so the objective lens using the image side of the telecentric optical system.

The field of view of this optical system is 80°, which has a larger field of view than the general projection system. This structure consists of two main groups of lenses, a negative focal length lens group and a positive focal length lens group. Also known as convex and concave lenses.For the large field of view optical system, the off-axis beam is first dispersed by the negative lens group, then converged by the positive lens group and imaged on the focal plane.

For lens type selection, the choice of aspheric lens can improve the performance of the system and have a significant advantage in reducing the aberration of the system. However, due to its high production difficulty and cost, aspherical lenses are not used in the optimization process to reduce the production cost of the system

◢Optical Lenses

As can be seen, the new pico-projection system uses a self-emitting Micro-LED array as the display light source, which improves energy utilization and reduces stray light interference compared to conventional DMD micro-reflector systems or LCOS liquid crystal light panel systems. The projection objective consists of a combined color optical prism and an imaging ac vivisection object, The design of this micro-LED system provides a reference and technical support for the future development of portable, lightweight, and self-illuminated microprojectors.

As can be seen, optical lenses play a significant role in human life and the development of science and technology, and the development of various fields cannot be separated from optical lenses, such as the above-mentioned article mentioned in the plano-concave lens, plano-convex lens, optical prism, optical mirror.

CLZ Optical Co., Ltd.is one of China's leading optical manufacturing companies. We manufacture a wide range of optical components for many different fields like lndustrial Laser, Consumerproducts, Environmental Monitoring, Photography and Aerospaceand R&D.We provide service of custom OEM.Main products are spherical lenses,optical windows,optical prisms,cylindrical lenses,optical mirror.Many kinds of substrates available such as optical glass,fused silica,silicon,sapphire and so on.

Please contact us!