The response time is a computer,displayimplementThe concept in many fields, such as imaging, refers to the response time of the sensor when a step value changes from no-load to load on the network.It is usually defined as the time required for the sensor to reach 90% of the final value after the test quantity changes a step value.The impact of the network on the overall response time is achieved through different mechanisms.In the field of imageLiquid crystal displayResponse time, yesliquid crystalThe speed at which each pixel of the display reacts to the input signal, that is, the time required for pixels to turn from dark to light or from light to dark (the principle is to apply voltage inside the liquid crystal molecule to twist and recover the liquid crystal molecule).The commonly said 25ms and 16ms refer to thisreaction timeThe shorter the reaction time, the less the user will feel the tail shadow dragging when watching the dynamic picture.The reaction time is generally divided into two parts:rise time (Rise time) and fall time.
The impact of the network on the overall response time is achieved through different mechanisms.The selected protocol (such as frame relay or ATM, EIGRP or OSPF) will greatly affect the delay time of data transmission in the network.These times include processing delay (the host receives the data packet and obtains various information), queuing delay (when other information packets appear), transmission or continuous transmission delay (the time of the first bit and the last bit in the transmission frame), and transmission delay (the time when a data bit passes the link, which depends on the physical medium and distance).Packet corruption and loss will also reduce the quality of information or increase additional delay, because retransmission is required.In the enterprise network of ground transmission, waiting and transmission delay are the main problems of network delay.For satellite networks, transmission delay (plus access protocol) is the main problem.The impact of server delay includes server itself and application design.The performance of the server itself includes the speed of the processor,storageAnd I/O performance, hard disk drive speed, and other settings.Application design includes structure and algorithm.
structure
The application delay is affected by several independent factors, such as the application design (such as the stability of the call), the size of the transaction, and the selected protocol (such asUDPOr TCP), and the network structure.When completing a certain transaction, the fewer round trips an application needs, the less it is affected by the network structure.However, since retransmissions are required, the number of round trips per se may depend on the network structure.
User experience
Computer users hate waiting.In a large number of processing environments, the response time of more than 3 seconds will seriously affect the work efficiency.However, the end users' feelings are not just about absolute time. Their expectations for response time refer to previous experience, and this expectation is relative to the benchmark performance of the application they use.If the current experience of using the app is very different from previous experience, the number of complaints and calls for support will multiply.
importance
The problem of application response time increases rapidly with the increase of server based applications.Determining the cause of application delay becomes a difficult task.The network management manager of a financial company in the Fortune 500 said that they spent too much time searching for problems. The manager added: "Even if the technician has identified the fault as a problem in the network, only 50% of the cases are really network problems. Sometimes we have to send everyone out just to find out where the problem is.".
Maintenance and management
The enterprise requires its network, application and MIS managers to ensure that key business related applications must run smoothly on the network.Determining where the problem affecting application performance is and who is responsible for solving it is a time-consuming and challenging task for IT departments.Due to the lack of experienced personnel and human resources, all enterprises want to save time and effort to maintain and manage response time.[1-2]
operating system
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Response time of operating system
In the operating system, response time refers to the time when the user sends a request or command to the system to respond (respond).
The system response time includes two aspects:
The length of time and the variability of time.The user response time should be moderate. If the system response time is too long, the user will feel uneasy and depressed. If the response time is too short, the user will sometimes speed up the operation, resulting in errors.The variability of system response time refers to the deviation from the average response time.Even if the response time is relatively long, low response time volatility can help users establish a stable rhythm.Therefore, the system response time shall adhere to the following principles:
Response time length interface design
0-10 seconds The mouse displays as an hourglass
From 10 to 18 seconds, the micro help displays the processing progress
Display processing window or progress bar for more than 18 seconds
When a long time processing is completed, a completion warning message should be given
Liquid crystal display
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CRT displayAs long as the electron beam strikes the phosphor, it will emit light immediately, and the glow residual time is extremely short, so the reaction time of traditional CRT displays is only 1~3ms.Therefore, the reaction time is generally not mentioned in CRT displays.And becauseLiquid crystal displayThe twist of liquid crystal molecule is used to control the light on and off, and the twist of liquid crystal molecule requires a process, so the reaction time of liquid crystal display is significantly longer than CRT.
definition
becauseLiquid crystal moleculeWith the rotation of, each sub pixel on the LCD screen changes from the previous frame color brightness to the next frame color brightness. There will be a time process, which is commonly referred to as the response time.Because each pixel is differentGray scaleThe conversion process between (i.e., between brightness) is very complicated and varies in length. It is difficult to use an objective scale to express it.Therefore, the existing definition of liquid crystal response time in the industry attempts to take the conversion speed of liquid crystal molecules from all black to all white as the epitome of the overall response time of the panel to representLCD panelIt is also called "On/Off" response time.Since the conversion speed of liquid crystal molecules from black to white and from white to black is not exactly the same, in order to mark thereaction rate Now, the definition of response time is basically based on the whole process response time of "black → white → black" (light -->dark -->light).
In fact, the conversion speed and torsion angle of liquid crystal molecules are determined by the applied voltage.From all black to all white, the liquid crystal molecules face the maximum torsion angle, and a larger voltage is required, at this time, the liquid crystal molecules have a faster torsion speed;The smaller range between all black and all whiteGray scaleChange, it needs to apply a small voltage to carry out accurate and fine angle control, so the torsion speed of liquid crystal molecules is slower.Generally speaking,LCD panelThe response time between black and white is the fastest, while the response time between other grayscales is also the response time of most different color changes, which is much slower than that between black and white.In this way, traditional On/Off uses black and white conversion time to represent the LCD response time, which can not accurately represent the overall response time of the LCD panel.
development
From 25ms to the well-known 16ms to 12ms,reaction timeIs constantly shortened,Liquid crystal displayThe old ideas that are not suitable for entertainment are being challenged greatly.You can do a simple conversion first: 30 milliseconds=1/0.030=33 frames per second;25 ms=1/0.025=40 frames per second;16 ms=1/0.016=63 frames per second;12 ms=1/0.012=83 frames per second.It can be seen that the birth of 12ms means a great progress in liquid crystal manufacturing.
However, it should be noted that the LCD has a scanning frequency limit, especially for the field frequency (also known as the refresh rate), many of them are limited to below 75Hz. In general, 75Hz means that 75 frames are refreshed in one second, which seems to be less than the 83 frames per second corresponding to 12ms.
In fact, the 12ms we mentioned abovereaction timeIt refers to the time required for switching between all black and all white pictures. The driving voltage required for switching between all white and all black pictures is relatively high, so the switching speed is relatively fast, which can reach 12ms;Most of them areGray scaleThe driving voltage required for screen switching (the essence of which is that the liquid crystal is not completely twisted and transparent) is relatively low, so the switching speed is relatively slow.So to sum up, the 75Hz refresh rate in grayscale images can meet the requirement of 12msLCD panelNeeds.
According to the data sheet
Response time 30 ms=1/0.030=the display can display 33 frames per second, which can meet the needs of DVD playing;
Response time 25 ms=1/0.025=the display can display 40 frames per second, fully meeting the needs of DVD playing and most games;
However, to play such intense action games (such as QUAKEIII/UT2003/DOMIII) and fast pursuit games without drag, the required screen display speed should be more than 60 frames per second, that isreaction time=1/The display can display 60 frames per second=16.6 milliseconds.
choose
In actual product applications, desktopLCDLow at the beginning of the interviewresponse speedIt has been criticized all the time, and some FPS game lovers still have no choice but to choose CRT monitors.However, as early as 2007, LCD monitors with 8ms response time have been launched in the display market.With the continuous development of the display industry, there have been a considerable number of manufacturers in the target market, such as ASUS, Samsung, LG, etc., who have begun to notice that consumer demand has gradually shortened the response time of LCD monitors. For example, when 19 inch LCD monitors were mainstream desktop sizes, ASUS VW193DR, VH196D and other productsSamsung 943NWLCD products such as LG 1942SP are equipped with 5ms response time, and the defects of tabletop LCD images, especially the dragging of dynamic images, have begun to be forgotten by consumers.Today, mainstream desktop LCD displays have reduced the response time to 2ms, making the smoothness of the picture more and more high.
Not only the traditional CCFL backlight LCD display, but also a large number of popular LED backlight models with 2ms response time have been put on the market. Represented by the 2ms response mercury free liquid crystal of ASUS MS series, domestic liquid crystal manufacturers have begun to follow closely. Samsung, LG and other Korean manufacturers continue to release products with 2ms response time.
