An American working in England jacobian parkins had a new discovery, a discovery that led to the invention of the refrigerator. In 1834, he found that when some liquid evaporation, there will be a cooling effect. Perkins asked a group of skilled worker to produce a model confirms that the idea of the work.Sure enough, the device really have some ice in a night. Artisans with ice, excitedly jumped into a cab, overshot the housing of perkins, show him the results. Perkins now getting on in years, although he is not in the market to sell their inventions, but harrison's work for household refrigerators laid the road early man.
Sell inventions people living in Australia a Scottish printer John harrison. Harrison is likely in the case of don't know about perkins results found that the cooling effect. Using ether to clean metal type printing, one day noticed the cooling effect of the material. By 1862, he listed the first refrigerator. Harrison also set this at theuniversity a beer factory in Victoria for the first refrigeration workshop. At the end of the 19th century, only specially made ice house to enjoy this benefit the rich. Most people expect is a freezer. At that time, the refrigerator is one of the most important purposes on the ship. Large cold storage means that ships can navigate over long distances with edible meat, such as lamb to export to Europe from New Zealand. German engineer Karl von - linde in 1879 produced the first household refrigerator. But before electric refrigerator invented in the 1920 s, the refrigerator is not mass into the family.
The world's first "household refrigeration equipment appeared around 1910, 1913, he created an artificial operating household refrigerator, Carl weiner, companies in the United States for the first time in 1918 successfully developed automatic commercial and household refrigerators, sold about 1920 units by 1920, 1926 American singular company, after 11 years of experiments, creating the world's first refrigerator sealed refrigeration system, the first domestic absorption refrigerator was developed in 1927.
Since the first refrigerator has been more than half a century, the current worldwide each year output in more than 40 million sets of a refrigerator, which yields the top several of the country is the United States, Russia, Italy, Japan and other countries. There are many different kinds of refrigerators, according to the refrigeration form to points, can be divided into steam compression type refrigerator, absorption - dispersive (hereinafter referred to as absorption refrigerator) and semiconductor refrigerator freezer, etc.; According to body shape can be divided into vertical, horizontal refrigerator freezer, coffee and cooking utensils combination, etc.; According to the type of the door can be divided into single, two-door refrigerator, three refrigerator freezer and multi-door refrigerator.
(1) steam compression type refrigerator
Compression type refrigerator according to refrigeration methods of cooling type can be divided into direct and indirect cooling type two kinds. In the freezer, the cooling by natural convection cooling food, general directly installed on the top of the freezer evaporator, in the bottom of the freezer for another small evaporator, or put the freezer part cooling points into the freezer, fridge with freezer refrigeration to air conditioning for food.
Cooled between most of the evaporator in the freezer of a refrigerator and freezer between interlayer, see in in the evaporator, can only see some wind hole, the sandwich has a miniature electric fan will blow out air conditioning and refrigeration effect, the fridge has automatic defrosting device, therefore also called "frost-free refrigerator."
Compression type refrigerator according to the structure can be divided into single, two-door several and different departments. A single share the door is a compartment of his fridge and freezer.
Three refrigerator freezer, freezer and fruit room door, respectively was conducive to the preservation of fruits and vegetables. Three-door refrigerators have on the door is equipped with desirable ice, cold drink of water, not only brings more convenience to consumers, but also can reduce the capacity loss.
Multi-door refrigerator generally no freezer, fridge, mild freezer, the fruit. In order to use convenient, its mild freezer (keep temperature 0 ℃ or so) and fruit chamber adopts draw-out type structure. The refrigerator under the mild freezer location generally is in the freezer, can save frozen food and marked need to long time storage.
(2) to absorb - dispersive refrigerators
Absorption - dispersive structure and compression type refrigerator freezer, is divided into the box body, refrigerating system and control system three parts. Household absorption refrigerator heat sources can be used as the power, such as natural gas, oil, gas, solar energy, etc. So this kind of refrigerators are equipped with gas, electricity and heating device, the device is composed of burner, automatic ignition device, temperature controller. Burning with safety device, when the burner flame, feel the flame temperature thermocouple can automatically disconnect gas path, in order to ensure safety. There are three kinds of filling material in the refrigeration system, refrigerant ammonia, absorbent water, a hydrogen or helium diffusion agent.
(3) the semiconductor refrigerator
Semiconductor type refrigerator and compression type refrigerator is the main difference between refrigeration systems, semiconductor refrigerator is to use semiconductor thermoelectric phenomenon, formation temperature and cooling. Its advantage is, small volume, light weight, high reliability. Because the semiconductor refrigerator with no mechanical transmission device, so no noise, no wear, simple operation, convenient maintenance; And because it no refrigerant, so no refrigerant leakage and pollution problems. Semiconductor refrigerator can compensate for the lack of compression type refrigerator. In general, the refrigeration temperature is low, it has aroused people's attention.
Domestic research status of refrigerators
Refrigerator in China started relatively late, the first refrigerator was produced by shenyang medical equipment factory in 1954, 200 litres of single refrigerator: starting in 1956, the health departments of some of the medical apparatus and instruments factory start with the refrigerator production capacity, and into the small batch production, refrigerator double production year after year in the early 80 s, 1983 annual production of about 1983, 1984 annual output more than 400000 units, at present the country to determine the appointed refrigerators in home appliance, the introduction of more than 50 refrigerator production assembly lines, annual output capacity of more than 15 million units, the specification has more than 50 to 200 litres a variety of series of large fridge, varieties have a single-door ZhiLengShi, two-door, many, type, also have cooled. In the 90 s, the refrigerator note number has high efficiency, intelligentize and many more temperature multi-function direction.
Since November 1999, the company to launch its first digital refrigerator after [1], by the media about network refrigerator's news is thriving. Proposed his own view to this, the personage inside course of study: now domestic refrigerator is too early to make network, abroad network refrigerator is just beginning. Announced the domestic many enterprises development, and even introduced the network refrigerator, is nothing more than in manufacturing, a stunt to attract public attention, or from a packaging strategy of the product image. So network refrigerator was just hype, at present a few years is unlikely to scale listed, even if listed, buy also not much. Experts pointed out: the development of network refrigerator, first of all must have network environment. But for now, we haven't this web based.
Domestic production management is still very backward, and now there are a lot of analysis is manual, still far away with the computer data statistical analysis, the domestic various enterprise resource management, planning, data statistics and analysis, and supplier of computer management were scarce, on this basis, make network refrigerator, is at the risk of manufacturing stunt. Also at present, the vast majority of Chinese consumers have not yet reached the income to buy so expensive network refrigerator, enjoy its so-called many convenience. As the Chinese market the huge consumer groups - people, they pay attention to the performance of the product, price, brand, etc., rather than a "rhetorical" products.
As a result, the trend of the development of the network refrigerator as the fridge of the future, enterprises should pay more attention to, strengthen scientific research and development, to further reduce the cost. Believe that as China's network environment construction, network refrigerator may be real to market in the near future, serve the public.
Abroad research status of refrigerators
With the continuous development of economy, its diet culture has been developing, improving people's life-style, diversified demand for food, and more and more families women into professional class, so the higher and higher demand for household refrigerators, requiring refrigerator function the more the better, the greater the volume, the better. 1996 Japanese refrigerators sales to 4.95 million units, which accounted for 30% of 120 litres of the following (mainly for hotel, hotels and other commercial), more than 300 litres of 57%, more than 400 liters showed a trend of fast growth, about 70% multi-door refrigerator. Therefore, in order to adapt to market needs, to better meet the growing consumer life demand, Japan's refrigerator manufacturing company continuously improve its own original products, quickly develop new products, make refrigerator function more perfect, more complete specifications, such as automatic ice-making, adopt frequency conversion or double rotor rotating compressor, fuzzy logic control, automatic without CFC, deodorant antibacterial, technology has been widely used in refrigerator.
At present, the biggest influence product structure adjustment to the refrigerator, the most outstanding, the most pressing problem is CFC cooling limit and disabled. International community control of the CFC and gradually ban is a foregone conclusion, refrigerators will therefore face a retrofit task, this is the refrigerator industry must face up to reality. Countries are trying to speed up the research and commercialization process of various kinds of new type refrigeration system.
In regard to the development of more energy refrigerator, absorption, adsorption refrigerator abroad has developed rapidly, in recent years, Japan's sanyo company in terms of absorption refrigerator broke through some technical difficulties, the development to the level of the power consumption can be similar to compression type refrigerator. The world absorption and adsorption refrigerator production capacity of about 1.5 million units, with Sweden, and Switzerland's production, most, quality is best, solar refrigerators, semiconductor refrigerator is more compelling new products in recent years.
In order to more scientific storage and keeping fresh food, foreign refrigerator also increased the function of quick freezing and rapid thawing. Quick freezing is to make the bottom temperature of freezer compartment - about 40 ℃ low temperature, let food quickly through 1 ~ 5 ℃ ice crystal formation prevents damage to the nutrition ingredient, keep the fresh degree of the original food; Quick freezing is in the refrigerator to establish rapid thawing room, by thawing fan, air blowing people of refrigerator freezer to thawing room, unfreezing indoor quick freezing food, to meet the needs of the short-term preservation storage.
Refrigerator is main power consumption of household appliances in the family, therefore the current factories and research units are developing compact refrigerators. Use scroll compressor, not only reduce the volume of the compressor, lose weight, and reduce energy consumption. Japan 100 w above rolling rotor compressor has been put into use, the power consumption than similar refrigerators power saving 20% ~ 25%; Application of the microcomputer control refrigerators can be energy-saving 15% ~ 15%; Improve the thermal insulation layer, refrigerator insulation thickness increased to 3 inch, it can power saving 14%; Application of new thermal insulation material, Toshiba application together the new material of chromium silicon oxygen, make the refrigerator power saving every month 2 degrees, application of the above all kinds of new technology in order to achieve the purpose of energy saving.
Since November 1999, the company to launch its first digital refrigerators, refrigerator's news is about network media '.
In December 1999, LG company new MP3 network refrigerator.
In Shanghai on June 18, 2001, the 10th information communication show, Ericsson and electrolux cooperation exhibited an intelligent network refrigerator.
On October 23, 2001, the United States passed the provincial certification ling network refrigerator. On October 26, 2001, the first intelligent network refrigerator in Denmark.
South Korean LG company in the same year also to market its own "network refrigerator".
What is the network refrigerator? Network achieving the operation, control of freezer refrigerator is network. Consumers can go online to check in the inventory of food, food is expired or barcode on food packaging, food will automatically thaw, etc; The refrigerator door had a 15 inch LCD monitor, the user can through the fridge to get to the Internet, playing video phone and video; LCD can also display the temperature inside the refrigerator and the shelf life of food; If the fridge out of the question, it can also automatically notify maintenance service center.
Network refrigerator market present situation how? When a reporter asked about the more than 10 customers ready to buy refrigerators, most do not know much about that. One of the old comrades to the reporter puts forward such a question: the main function of the refrigerator is not store food, with good quality fresh? To attach a computer function necessary? And the price is high, life is too far away from people?
Then the first turn on the refrigerator to the market network of samsung, what is your interpretation? Suzhou samsung electronics co., LTD. Marketing Department minister yuan said, is to launch the network refrigerator, is to reflect the trend of the development of the refrigerator, samsung's brand image and own advanced technology, designed to show the samsung has power to bring consumers the best quality of life.
Introduction of AT89C51
With a 4 k byte flash is AT89C51 is programmable can erase the read only memory (ROM) of low voltage, high performance CMOS8 microprocessors, commonly known as the microcontroller. AT89C2051 is a kind of zone 2 k byte flash programmable microcontroller can erase the read only memory (ROM). MCU can erase read-only memory can be erased repeatedly 100 times. The device adopts the ATMEL high-density nonvolatile storage manufacture technology, and industry standard of MCS - 51 JiaoXiang compatible instruction set and output pipe. Due to the multi-function 8-bit CPU and flash memory in single chip AT89C51 of ATMEL is an effective and micro controller, AT89C2051 is a streamlined version of it. AT89C microcontroller for many embedded control system provides a high flexibility and low price.
1. Main features:
Compatible with MCS - 51, 4 k byte programmable flash memory, the life expectancy of 1000 write/cycle, data retention time for 10 years, the static work of 0 hz - 24 hz, tertiary program memory lock, 128 * 8 internal RAM, 32 programmable I/O lines, two 16 bit timer/counter, five interrupt source, programmable serial channels, low power idle and power down mode, the on-chip oscillator and clock circuit.
2. The pin:
VCC: power supply voltage.
GND: grounded.
P0 mouth: P0 mouth for an 8-bit leakage level bidirectional I/O mouth, each foot can absorb eight TTL gate current. When P1 mouth pin write 1 for the first time, is defined as the high impedance input. P0 data storage can be used in external applications, it can be defined as the data/address of 8. The FIASH programming, P0 mouth as the original code input port, when calibrate the FIASH, P0 output the original code, P0 outside must be up at this time.
P1 mouth: P1 mouth is an internal pull-up resistors 8-bit bidirectional I/O mouth, P1 mouth buffer can receive 4 TTL gate current output. P1 mouth pin written 1, is the internal pull-up to high, can be used as input, the P1 mouth is external drop-down as low electricity at ordinary times, the output current, it is because of the internal pull-up. In the FLASH programming and calibration, P1 mouth as the eighth the receive address.
P2 mouth: P2 port for an internal pull-up resistor 8-bit bidirectional I/O mouth, P2 port buffer can receive and output four TTL gate current, when P2 mouth by writing "1", the internal pull-up resistor pin is pulled, and as an input. And so as the input, P2 port pin is external pull low, the output current. This is because of the internal pull-up. P2 mouth when used in external program memory or 16-bit address external data memory access, a high eight P2 output address. When it was given address "1", took advantage of the internal pull-up, when external eight address data memory read and write, P2 output the contents of the registers, its special function. P2 port in the FLASH programming and the check and accept high eight address signal and control signal.
P3 mouth: P3 mouth pin is eight to bring the internal pull-up resistor bidirectional I/O mouth, four TTL gate current acceptable output. When the P3 after writing a "1", they are the internal pull-up to high level, and is used as input. As input, due to external conditions for low level, P3 port will output current () this is because of the pull-up.
2. The oscillator characteristics:
XTAL1 and XTAL2 are reverse amplifier input and output respectively. The reverse amplifier can be configured to the on-chip oscillator. Crystal and ceramic oscillations can be adopted. Such as driven by external clock source device, XTAL2 should not be answered. More input to the internal clock signal to pass a binary frequency trigger, so external clock signal pulse width without any requirements, but must ensure that the pulse width of high and low level requirements.
3. The chip erase:
The entire array and three locking PEROM electrical erasure can be combined with the right control signal, and keep the ALE pin is in low level 10 ms to complete. In array chip operation, code by writing "1" and not in office all empty storage bytes have been repeated programming before, the action must be taken.
Moreover, AT89C51 is equipped with static logic, can be in low to zero frequency under the condition of static logic, software supports two optional power down mode. In idle mode, the CPU to stop working. But RAM, timer, counter, a serial port and interrupt system is still at work. In a power down mode, save the contents of the RAM and freeze oscillator, prohibit the other chips used functions, until by a hardware reset.
