Everyone should be no stranger to the "Tesla Gigafactory". There is a set of stunning production line drawings that shocked the entire network. Just look at those robotic arms that are swiftly moving there, performing their duties in an orderly manner. The sense of technology is bursting.
Regardless of the tall and mighty machine tools and manipulator arms, they do all rigorous and meticulous work. Especially for products with extremely high safety requirements like cars, the scores are not bad for each nail and riveting, and for retreating and entering.
Although there is a rigorous computer system behind it to give orders, but in the end, to convey the instructions and achieve precise control of the movement time and position of each component, a small component is indispensable: the encoder.
An encoder is a device that compiles and converts signals or data into signal forms that can be used for communication, transmission and storage. It is mostly used to realize the measurement and transmission of angular displacement and linear displacement information.
In fact, we are enjoying the convenience brought by encoder applications every day. When it comes to motion control, it mostly appears. For example, the elevators, cars, vending machines and printers you use. Emmm... sometimes it can even solve your boring problems, such as:
A German engineering student used a broken Canon 850i printer to modify the "stupid" little device, and people can't help but indulge in playing with it. Among them, a common DC motor with a photoelectric encoder is used to drive the print head, and the accuracy of the servo-controlled operating arm can reach 0.1mm.
In addition to civilian use, the encoder has more industrial and scientific applications, which is also its most important application direction. For example, CNC machine tools and robots in manufacturing, or various high-precision, closed-loop speed control systems such as aerospace, large-scale photoelectric theodolites, radars, and ground commanders, as well as the speed measurement of servo systems, can be seen. Figure.
Can accurately align the satellites, they also need the blessing of the encoder
Photoelectric and electromagnetic are two more common types of encoders (divided by principle). For the latter, the former can achieve more precise measurement, higher resolution, and more compactness. Therefore, in high-end applications such as smart manufacturing just mentioned, optoelectronics are more favored.
With manufacturing upgrades and the emergence of higher-level motion control requirements, photoelectric encoders have also become a member of the automation system that needs further growth. How to move towards higher performance and keep up with the times is an important issue for many encoder suppliers.
With high resolution, miniaturization, and high stability, how do photoelectric encoders meet the needs of new technology upgrades?
Photoelectric encoders, as the name suggests, are based on photoelectric conversion technology. The traditional photoelectric encoder mainly consists of the following parts: light source, code disc, slit, photoelectric receiving element, shaft system, processing circuit and output. The main body is composed of a code disc and a photoelectric detection device, which is the key to determining the overall module performance.
The motor and the code disc are coaxial. When the motor rotates, the code disc and the motor rotate at the same speed, and the light-emitting diodes, detectors, etc. form a photoelectric and detection device to output signals.
In addition to transmissive, there are reflective photoelectric encoders
In the automation technology upgrade, the application has further enhanced the requirements of the accuracy, resolution, size, and reliability of the photoelectric encoder. However, the internal relationship of key components makes it very difficult to meet these properties at the same time.
As we all know, hoping to improve the accuracy and resolution of the photoelectric encoder, increasing the number of code channels is the most direct way. This corresponds to two ways:
One is to increase the size of the code disc. Obviously this is undesirable, not to mention that it is not in line with our original intention to reduce the size (size will limit the use of photoelectric encoders), and the number of detectors will increase accordingly, which will increase the internal mechanical and optical systems. The difficulty of design. At the same time, the increase in signals also means the complexity of the corresponding processing circuit design. Regardless of the difficulty of development, cost or equipment reliability, it is not very friendly.
The other is to increase the number in a limited area by reducing the width of the code channel. However, in this case, it is very difficult to evenly describe the code channel. If the uniformity cannot be satisfied, the resolution and accuracy will also be affected.
This irreconcilable contradiction lies here. If you want traditional photoelectric encoders to achieve various ideal performances at the same time, you can really only say one thing:
Jumping out of existing technology, adopting new coding theory, and developing a new type of photoelectric encoder is a new way. For this reason, for its internal components, new and higher-standard customization requirements have emerged.
As the core part, the photoelectric detection device has become the key. Encoders have more stringent requirements for the speed, sensitivity, anti-crosstalk ability, power consumption, consistency, and operating temperature of photoelectric devices (photodetectors, light sources).
If the device provider does not have strong independent R&D and production capabilities, and rich customization experience, it will not be able to help encoder manufacturers keep up with the "call of the times".
Hamamatsu can provide transmissive and reflective photoelectric encoders (including grating scales) with a total photoelectric detection solution covering detectors (PD, optical IC, CMOS), light sources, and electronics. Based on the entire line of proprietary semiconductor design, processing, and packaging technologies, it can meet customers' highly customized needs and provide mass-produced products with high sensitivity, low noise, and high reliability.
In the past 10 years, more than 100 customized solutions and mass production supply of optoelectronic devices for encoders have been completed, and the current production capacity has reached 800k pcs/month (PD + LED total), and it has a very high market share in Japan.
Hamamatsu Optical Semiconductor's research and development history can be traced back to 1958, and since then it has been adhering to the concept of In house for the full production line. Therefore, through rapid development and the wider application of optoelectronic semiconductors, a wide range of products has been gradually expanded, and many unique semiconductor technologies have been honed.
# Through hole processing technology
Using MEMS technology, a through hole is formed on the PD chip (photodiode), and special LEDs can be placed in it, realizing the integration of LED and PD chip level. The thickness of the PD chip can also be adjusted to keep the height of the LED consistent with the height of the PD photosensitive area.
# Low reflectivity shading film
By coating a light-shielding film on the surface of the PD chip, the reflectivity of the metal wiring and components outside the photosensitive area is reduced, and the signal-to-noise ratio has also been improved.
#FOP coupling
The Hamamatsu Micro Fiber Optic Board (FOP) is a collection of micro-sized optical fibers. It is a lens that can transmit light and images with high rate and low distortion.
Coupling the FOP with the photosensitive area of the detector can shorten the free optical path in space, help improve the resolution of the encoder and reduce crosstalk. And this is Hamamatsu's unique patented technology.
# Can be optimized for spectral sensitivity
From visible light to near-infrared, Hamamatsu can produce almost full-wavelength detectors. By matching the most suitable sensitivity detector to the LED selected by the customer, a high signal-to-noise ratio of the entire system is achieved.
# Improve the crystal structure to improve stability: current-limited LED
Hamamatsu has achieved higher reliability of current-limited LEDs by improving the crystal structure of the chip. In addition, the luminous diameter can also be designed according to actual needs.
# Possess its own IC design capabilities: realize the miniaturization and modularization of devices
In addition to the two-in-one combination of PD+LED from the chip level mentioned above, Hamamatsu has also implemented integrated design of PD and peripheral circuits, and designed special noise-reducing circuit structures to make the device easier to use and play Better performance. In addition, Hamamatsu can also provide integrated module products including detectors, light sources and readout circuits.
Although the encoder is small, it is an indispensable "screw" in the intelligentization of human production and life. Our country has also put forward the development strategy of "Made in China 2025" in recent years. One of the five policies is "innovation-driven", which clarifies the direction of manufacturing digitalization and intelligence.
Hamamatsu also hopes to create more suitable and high-quality core optoelectronic devices by better communicating the needs of encoder developers, and adding a force within its capacity to achieve this ambition.
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