Chapter 466 Three kinds of chips
The other party makes relays and electronic components. Gao Zhendong probably knows what the other party wants to do with 6013, contact materials, and it is most likely to be used for extremely important projects. Otherwise, the price of tungsten silver materials is still a bit pricey these days, and I would not dare to use it.
Gao Zhendong doesn't care much about what the other person uses it for. What he cares about is the other person's identity and factory.
For Gao Zhendong, if he wants to evolve direct projection lithography into micro projection lithography in the future, the step of automatic control of the movement of the workpiece table and mask table cannot be avoided, especially the workpiece table.
The automatic control of the workpiece table means that the problem of positioning the workpiece table during movement has surfaced.
Fortunately, with the current accuracy requirements, the motion control of the workpiece table uses a hand-driven gear and screw reduction mechanism. This thing has the advantage that the ratio of its motion state can be determined, such as through the gear ratio, screw Parameters such as twisting distance can be calculated directly.
In this way, it will be easier to do. Turn the hand crank into a motor, and then directly measure the rotation of the driving gear, and you can directly calculate the final distance of the workpiece table.
The best way to measure the rotation of the initial drive gear is undoubtedly a multi-turn rotary encoder. As for whether it is relative encoding or absolute encoding, it does not matter. In fact, the technology between the two is The only thing in common is that absolute encoding is more complicated, and according to Gao Zhendong's current requirements, a multi-turn relative encoder is enough.
As for the difference between absolute and relative, the main thing is that the position of the absolute encoder's rotating shaft strictly corresponds to the output value. The output is a number, and the angle of the rotating shaft can be determined through the output.
Whether the relative encoder outputs a number, no matter how it is output, its core is a signal related to rotation speed, direction, and rotation angle.
If we use a navigation system as an analogy, the output of an absolute encoder is similar to the output of a GPS, which is directly the result, while the output of a relative encoder is similar to the output of an inertial navigation system, and the final result depends on solving the output.
There is no difference between these two methods, but they are different in application situations, such as motor self-control. In general, absolute encoders are not as useful as relative encoders. The frequency signal output by the latter can be simply After processing and conversion, it is directly used to drive the PWM circuit and control the motor speed.
It’s just this thing. It has been produced in China for 80 years. Before that, imported products had been used since the 1950s, and it was not easy to import.
Gao Zhendong wants to find out through comrades from professional component factories whether encoders can be obtained now and what kind of encoders can be obtained stably. Even if they are both multi-turn relative encoders, the differences and know-how Still a lot.
If you can get the right one stably, then you don’t have to worry about this matter. If not, then you don’t have to do anything in this area.
After thinking for a long time, Gao Zhendong realized that it would be better to ask the 12th Machinery Department directly about this matter. The response there would definitely be faster and the situation more comprehensive than that of the factory. The appearance of this factory mainly served as a reminder to him.
Putting down the phone, Gao Zhendong asked someone to call Xiao Li.
After a while, Xiao Li ran over and shouted when he entered the door: "Teacher, what do you want me to do?"
Looking at his appearance, Gao Zhendong suddenly felt a little dazed. Many years ago, I probably looked like this when I entered Master's office.
Shaking his head and smiling, Gao Zhendong threw a cigarette to him, walked to the sofa and sat down.
"Two things. First, you go to our ministry and contact us. There is a factory that needs our 6013 materials. You go and implement this matter. Second, submit a report to the 12th Ministry of Machinery and inquire about the current domestic rotation. The situation of the encoder. ”
The previous matter is all about details and involves confidentiality work. It’s just right for Xiao Li to organize and implement it.
The latter one is very general and does not require much ability of the staff, but it is not suitable for making a big splash. It is just right for Xiao Li to do it.
Xiao Li wrote down what Gao Zhendong said, and Gao Zhendong added some relevant information and precautions to him. He turned around and ran away with his notebook to do some work. Before going out, he asked Gao Zhendong for the remaining half pack of cigarettes, saying frankly that the teacher's cigarettes were better.
——
On December 16, Gao Zhendong received a call from the 12th Machinery Department. It had nothing to do with the rotary encoder, but something about the photoresist and optical system that he asked the 12th Machinery Department to confirm.
In terms of photoresist, some comrades have already developed a negative photoresist and supporting drugs, and the speed is still very good.
Gao Zhendong doesn't care whether it is positive lithography or negative lithography. As long as he can determine which one it is, he can start the next step of work - making a mask.
If you don’t know the positive and negative values of the photoresist that can be produced, you can’t proceed with this step. The reason is very simple. The masks of the two are reversed.
As for the other thing, there is also clear news.
The Northeast Optics Institute has already figured out the first step of the optical system, which is to diffuse a laser beam into parallel light with a diameter of 160mm.
In fact, the optical system in this step is not particularly difficult or complicated. The main reason why it took so long is that the optical system is not as simple as putting a few lenses on it.
Even if refocusing is not required in the first step, optical paths such as beam expansion, collimation and homogenization are still indispensable, and engineering reliability, usability, adjustment, maintenance and other issues must also be considered. It can be said that, The design of the light path is only part of it.
Although it has been completed, there are still some gaps in direct delivery. Comrades from the Northeast Optics Institute still hope that the proposer of the project can go and have a look on the spot, so that they can make final adjustments and improvements. However, the Northeast Optics Institute did not know who the specific proposer of the subject was, so they had to inform the 12th Machinery Department to convey it.
Gao Zhendong thought about his time and decided to go there. A month would be enough, and other projects here would not allow him to leave for a long time.
After calculating the time, he replied to the comrades of the 12th Machinery Department that he was going to go there on Wednesday next week.
Putting down the phone, Gao Zhendong began to arrange his work.
There is no need to worry about Battle 6011. Everything is progressing normally, and the research team has basically solved any minor problems by themselves.
The courses at Beijing University of Technology are a problem, but considering that there is a high probability that I can go back and forth within ten days, this problem is not bad. If the arrangement is good, it only needs to be adjusted. Just one week of classes.
He arranged to go there on Wednesday next week. For this reason, he didn't leave until Tuesday's class.
Others, there is only one most important thing left, processing the mask.
Gao Zhendong took out three sets of drawings, which were the first three types of chips he was going to put into testing.
There are many digital logic circuits, but Gao Zhendong has only chosen these three for the time being. He has other preparations for the others.
——NAND gate, NOR gate, D flip-flop.
The reason why these three devices were selected is that these three devices are the basis of all other devices. In fact, the D flip-flop can also be composed of the first two devices, but it is of great significance and has a wide range of uses. Gao Zhendong also first introduced this thing The integrated circuit was produced.
And, OR, and NOT are the three most basic logical operations. They can form all logic circuits.
The NAND gate and NOR gate can complete the above three logical operations. The reason why it is not directly made into AND gate, OR gate and NOT gate is because in actual logic circuits, NAND and NOR operations are more common than AND and OR operations.
The first four models of the famous 74 series chips, 7400~7403, are respectively two NAND gates and two NOR gates.
As for other more complex logical operations such as identical or, exclusive or, and or, etc., they can all be decomposed into these three operations.
Among them, the XOR gate is special. Two XOR gates can form an RS latch. An RS latch plus two XOR gates can make a D flip-flop. Two D flip-flops can form an edge trigger. device.
The 8 edge flip-flops are a 1-byte register.
This is the reason why Gao Zhendong chose these three types of chips first. They can complete all logic circuits and at the same time can be more conveniently made into small-capacity memories, such as registers and temporary memories.
But it is not possible to use digital components to make large-scale data storage. The area occupied is still a small matter, and the main reason is that it is too expensive. Before the manufacturing process is high enough, the number of transistors per unit area is not enough. At this time, in order to achieve reliable and high-speed data storage, the cost of digital circuit storage devices with more complex structures is much higher than that of analog circuits.
Leave aside the problem of data retention when power is lost. Needless to say, a 1kByte data memory requires 8,000 edge flip-flops, a total of 16,000 D flip-flops. This is unacceptable and far less than transistors. If the memory is good, three transistors can store one bit of data.
Even so, D flip-flops still provide a convenient means for temporary storage of small amounts of data in engineering applications.
The three types of chips developed by Gao Zhendong are all 14-pin, which helps the 1274 factory unify the process and reduce costs.
The NAND gate has one pin each for power supply and ground. The remaining 12 pins are divided into 4 groups. Each group is a dual-input single-output NAND gate. In this case, there are 4 on a chip. NAND gates are available.
The NOR gate has the same structure as the NAND gate, except that the NAND operation is changed to the NOR operation.
The D flip-flop is a chip with two D flip-flops. That is to say, if used as a memory, a chip can store 1 bit. If reliability is not required, use the D flip-flop directly. If the device is latched, it can store 2 bits.
This is already a surprise to current automatic controllers. Can such a small chip store two bits of data?
No way, the memory back then was so expensive.
With the drawings in hand, Gao Zhendong called Yu Yongnian again and left the processing to him to implement.
(End of this chapter)