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Some time ago Xiaomi released the Redmi K40 Enhanced Edition, in addition to the game and heat dissipation performance, this phone is also equipped with the so-called 5P1G main camera solution, of which the G here represents Glass, that is, the use of a glass lens, P stands for Plasma, that is, plastic lens, for the convenience of writing, the following are used digital + P / G on behalf of the lens scheme. Glass lenses already have a lot of solutions in the supply chain, why are they only starting to be used on mass production machines now? What are its advantages and disadvantages?
The Redmi K40 Enhanced Edition uses ED lenses
The advantages of glass lenses balance optical quality and thickness
The glass-plastic blend of mobile phone lens lenses is mainly used to effectively balance optical quality and thickness.
With the continuous improvement of users' demand for mobile phone photography, manufacturers have begun to greatly improve in hardware, and the development of mobile phone cameras is showing a trend of multi-main photography, high pixelation, and increased sensor area, so the optical quality requirements for lenses have also increased, high pixels require higher optical resolution, and large sensors require longer actual focal lengths. In order to improve the optical quality, the number of mainstream mobile phone lens lenses has been upgraded from 5 to 6 to 7 to 8 to correct the optical path, but due to the limitations of mobile phone thickness, plastic lens transmittance, assembly accuracy and other factors, the number of mobile phone lenses is difficult to further increase.
Glass lenses can first reduce the thickness. Due to the better light transmittance and higher refractive index of glass, in the test, the supply chain company said that 8 plastic lens lenses can be reduced to 6 plastic lenses plus 1 glass lens to ensure that the optical quality is basically the same, and the transmittance is better than the 8P lens, so the thickness of the lens module can be reduced by about 0.5mm, which is also a bit of a breakthrough in the place where the thickness of the mobile phone is inextricably.
Second, glass-plastic mixing can effectively improve the assembly yield, thereby reducing costs. The more lenses the higher the assembly accuracy requirements, the yield will also decrease. Compared with 8P, 6P1G has one less lens to be assembled, and the yield of one assembly can be increased from 10 to 20% to about 40%, and the price of 8P lenses in the supply chain remains high, mainly because the assembly yield is not enough.
Plating of the lenses
Image source: AAC Technologies
Third, glass lenses can be optimized for more layers of coating. At present, most of the mobile phone lens coating uses a high-temperature process, in which the plastic lens is more likely to deform, resulting in a reduced yield, usually the coating does not exceed 5 layers. Glass lenses have strong high temperature resistance, as shown above, AAC Technology has made 20 layers of coating for their glass lenses to control reflection and glare and improve optical quality.
Price, the biggest factor hindering the popularity of glass lenses
The biggest problem that hinders glass lenses from entering the mobile phone field is price, so the place where glass lenses are used on mobile phones is often a place where cost is relatively less sensitive. Because the portable device lens design of mobile phones is very compact, in order to optimize the optical path, a large number of lenses use aspherical design, counting on the camera lens, it is a special lens, and its price naturally rises.
A glass lens, if you come to Hoya (Hoya), its price is about 1 US dollars, if it is a domestic manufacturer, such as Lianchuang Electronics, Lante Optics, its price is about 0.5 US dollars, that is, more than three yuan. The market price of plastic lenses is usually around 0.5 yuan / film, under the brutal competition of the domestic supply chain, the price of 5P lenses for secondary photographs at the middle and low end is more than three yuan, even if it is up to 6p, the price is 4-6 yuan. That is to say, the price of a glass lens can be worth a lens, and the cost advantage brought by its improved yield is difficult to play in the low-end machine. In addition, due to the need for focusing, the lenses used for focusing on the phone will only use plastic lenses to reduce quality and increase focus speed. Finally, taking into account the overall cost of mobile phones and the needs of optical quality, the glass lenses on mobile phone lenses are not more than 3 pieces in the current supply chain plan
However, many mobile phones also have glass optical components. For example, the prism used for refraction of periscope lenses usually uses glass in order to maximize the pass rate of light. There are also relatively insensitive costs, but for high light transmittance requirements of the under-screen fingerprint module. The second generation of lens scheme of the under-screen fingerprint module, simply can be seen as a low-resolution camera under the display, the lens of this camera is glass lenses, usually about 3 pieces.
<b>Glass lens processing method</b>
Common methods for producing glass lenses include <b>traditional glass processing, molding processes and WRG</b>.
The molding process has advantages over traditional glass processing. Traditional glass lens processing requires a complex process, and the shape of the lens is greatly limited. Compared with traditional glass processing, the process of molding glass is more difficult. To put it simply, it is to melt the glass first, and then take the mold to press it into the desired shape, but due to changes in temperature, pressure, and the precision of the mold, further polishing is needed after the processing is completed, so the process is very difficult. However, compared with traditional glass processing, it has the advantages of high efficiency, low cost, and unlimited shape of the lens produced. At present, the main manufacturers of energy production are Mainly Japan's TAG Heuer (HOYA), domestic Lianchuang Electronics and Lante Optics.
Another type of process is WRG, which is the processing technology of the glass lens in Xiaomi's 1G5P. WLG is the abbreviation for Wafer Level Glass, and WLO is the abbreviation for Wafer Level Optics, both of which manufacture lenses in a manner similar to semiconductor processing. WLO, as the name suggests, covers a wider range, with plastic lenses and glass in range, while WLG refers specifically to glass. It is usually manufactured using the process of nanoimprinting.
Lens processing process
WLO technology is mainly in the hands of Heptagon (acquired by AMS), Himax Wonder Photoelectric, VisEra Caiyu, Anteryon (acquired by Jingfang Technology) and other manufacturers. WLG is mainly promoted by domestic manufacturerSacoustics.
In addition to mobile phones, automotive electronics is the future of glass lens applications
<b>Another market where prices are relatively less sensitive but sensitive to optical quality is automotive electronics. </b>In the automotive field, the average number of cameras continues to increase, and its lenses are mainly composed of glass lenses, and the market size is growing rapidly. According to Yole's forecast, cars are equipped with an average of about 1.6 cameras in 2018 and are expected to carry more than three cameras by 2024. The global car ownership exceeds 1 billion vehicles, with annual sales of about 90 million vehicles, if it is upgraded successively, the market size is about 10 billion to 15 billion US dollars per year based on the calculation of 10 US dollars per camera module. This market is large enough, in this market, Shunyu Optics from Yuyao has seized the opportunity and is currently the world's largest company in vehicle lens shipments.
Applications for in-vehicle lenses
The main difference between vehicle-grade and consumer-grade cameras is the working environment. The temperature difference requirement of the vehicle grade lens is high (-40 °C ~ 120 °C), and the glass lens has a lower thermal expansion and contraction effect and higher ambient temperature adaptability than the resin lens. The ADAS era has higher requirements for vehicle-grade lenses, so the current vehicle-grade lenses usually use 4G2P design to ensure that lenses can be imaged in various environments and achieve driver assistance functions.
The application of car camera in well-known car companies
Therefore, Lianchuang Electronic Automotive Lens, which has the production capacity of glass lenses, has obtained many customer certifications as an alternative to Shunyu. Including the vehicle manufacturer Tesla, the head of the self-driving solution provider Mobileye, Nvidia, and Valeo, Continental, ZF, Magna, Huawei and other Tier 1 manufacturers. In terms of the specific share of downstream customers, Lianchuang Electronics currently occupies about 35% of Tesla's share, winning the bid for 7 of The 8 lenses of Weilai, and is also the exclusive supplier of Nvidia ADAS lenses and the largest supplier of Mobileye.
<b>summary</b>
Glass lenses have theoretically higher optical qualities and thinner lens module advantages in mobile phone applications, and they can be used to replace two plastic lenses, which can improve lens yield and reduce the cost of high-end lenses. The higher cost hinders the application of glass lenses on mobile phone lenses, and in the second half of this year, there are glass-plastic hybrid mobile phone lens solutions in the supply chain, but the marketing of these programs also accounts for a certain component. Glass lenses are more used in less cost-sensitive places, such as prisms for refraction in periscope cameras, lenses for imaging in off-screen fingerprinting schemes, and lenses in automotive driver assistance systems that are becoming ubiquitous. Domestic supply chains are further expanding their territory and expanding their application scope in these areas.