MOS transistor switching circuit design knowledge oled module

1, MOS tube type and structure
FET is the MOSFET (the other one is JFET), may be manufactured or enhanced depletion type , P -channel or N-channel type of four kinds , but the practical application of only N -channel enhancement type MOS tubes and P -channel enhancement type MOS transistor , it is usually referred to NMOS, PMOS , or refers to two .

For both enhanced MOS, more commonly used is NMOS. The reason is that the on-resistance is small, and easy to manufacture . Therefore, the switching power supply and motor drive applications, typically using NMOS. The following presentation, also mostly NMOS based.
Parasitic capacitance exists between the three pins MOS transistor , which is not what we need, but because of the manufacturing process limitations arising . Parasitic capacitance makes the design or selection of the drive circuit will take some time , but there is no way to avoid back again in detail.
MOS tube can be seen on the schematic , there is a parasitic diode between the drain and the source . This is called the body diode , drive inductive loads ( such as motors ) ,Tsingtek lcd graphic display this diode is very important. Incidentally , only the body diode of the MOS transistor in the presence of a single , integrated circuit chip is usually not .
2, MOS conduction characteristics
A conduction switch means is equivalent to a closed switch .
The characteristics of NMOS , Vgs greater than a certain value becomes conductive , suitable for the case when the source is grounded ( low side driver ) , as long as the gate voltage reaches 10V 4V or on it.
Characteristics of the PMOS , Vgs less than a certain value is turned on, the situation is extremely suitable for the source when connected to VCC ( high drive ) . However, while the PMOS can be conveniently used as high-side driver , but the on- resistance is large , expensive, and less replacement types reasons, the high-side driver , it is usually used NMOS.
3, MOS switch losses
Regardless of the NMOS or PMOS, both the on-resistance conduction exists, so current will dissipate energy in this resistor, which is called the partial consumption of energy conduction losses . Choose a small on-resistance MOS tube reduces conduction losses. Now a small on-resistance power MOS usually around tens of milliohms , there are a few milliohms .
MOS is turned on and when the cut-off , certainly not instantaneous. There is a voltage drop across the MOS process , there is a current flowing in the process of rising , at this time, the loss of MOS tube is the product of voltage and current , called switching losses. Switching losses are usually much larger than the conduction losses and switching frequency , the faster , the greater the loss .
Conducting product of the instantaneous voltage and current is large, will cause great damage . Shorten the switching time ,Tsingtek Character OLED Display conduction loss can be reduced every time ; reduce the switching frequency , the switching frequency can be reduced per unit of time . Both approaches can reduce the switching losses.

SUMMER purchase Character LCD Modules misconceptions

Certainly the best IPS panel

With the increasing demand of consumers , many photography enthusiasts or players can not find a primary design display products in the Heart of the overall delisting after CRT monitors , LCD monitors because TN panels can not meet their needs in terms of reliability of color , and wide viewing angle LCD price too expensive. But this year appeared on the market using low-cost panel display products are well up for this gap, but also become the focus of chase .
Cheap wide angle LCD has become a hot topic in recent years

In these displays on the market used mainly from the C-PVA panel , MVA panel and the launch of three IPS panel specifications . But be induced by lack of expertise in the field of television and salespeople , many consumers have a wrong idea : IPS panel is the best. To actually ask inquisitive IPS panel in the end was good , I believe that consumers rarely say the system .

VA class IPS panel with wide viewing angle panel have their own advantages and disadvantages , OLED Display Module not the presence of overwhelming victory

VA classes and a wide viewing angle panel compared the advantages of IPS panel is relatively fast response time, and more accurate color reproduction ; while the VA class is the biggest advantage of the panel have a higher contrast ratio ( note that this is not a dynamic contrast ratio, and static contrast ratio ) , many with C-PVA or MVA LCD monitors are equipped with 3000:1 native contrast ratio , such as Samsung F2380, BenQ " steel Man" series LCD EW2430V etc. , in addition to BenQ also said it will launch a native contrast ratio of up to 5000 : 1 MVA wide viewing angle panel products ( BenQ will call Li Rui black screen ) and high contrast is able to demonstrate the advantages of a richer picture level , while more pure black screen , help watch movies , play games ; high enough contrast IPS panel has also been plagued by problems , there are many user feedback , said IPS panel " black black does not go " , but also because of this reason that the official result .

C-PVA or MVA panel also has a very reliable color performance , this part of the IPS matched

After a variety of VA class before we tested ( including sharp black screen MVA and C-PVA) liquid crystal display products , you can see them and IPS panel , almost completely cover the sRGB color space , so even as a design drawing or photography repair film, which also can be well done.
And this idea is basically shopping guide them to better sell their products and instill consumer , with word of mouth among users COG LCD Module, it has almost become a "truth" , so here we are once again reminded us of two type of wide viewing angle panel each have different strengths and weaknesses , in the purchase or to take into account the actual needs .

Character LCD Modules TV Daily Care and Maintenance

With the popularity of large-screen LCD TV , has brought us a new visual enjoyment while later use in maintenance problem has become a focus of attention of many consumers . If maintained properly , not only affects our visual experience , but also greatly reduces the service life. So how proper maintenance and use of the LCD TV? Here we come to learn about.
With the popularity of large-screen lcd module TV , has brought us a new visual enjoyment while later use in maintenance problem has become a focus of attention of many consumers . If maintained properly , not only affects our visual experience , but also greatly reduces the service life. So how proper maintenance and use of the LCD TV? Here we come to learn about.

TV encyclopedia knowledge LCD TV Daily Care and Maintenance 1 , moisture, dust , lightning : keep the machine working environment is relatively dry, do not allow water to enter the body ; when the machine is not in use , consider using dust ; as plasma and peripheral configuration of a lightning electrical outlet on it.

2 , heat : the heat generated by high-power plasma TV can be seen as the number one enemy , so pay special attention to the use of thermal plasma TV .

3 , screen burn : a long time because the screen is a still picture playback fixed partial motion blur generated by the burn , which is a plasma TV itself characteristics of the decision .

4 Clean: regular plasma TV screen to do the cleaning , keep the screen surface bright as new is a good way to maintain picture quality .

5 , voltage: mini lcd module the conditional case should plasma TV provides independent power lines, or to add a stable power supply is a good choice .

LCD Character LCD Modules stitching program analysis

did program | lcd module LCD stitching program analysis : did the rapid development of LCD splicing , for airports, subways, train stations and other places of these overcrowded public transport , safety monitoring and flight , train schedule information in real time , clear and accurate display , is extremely important. Narrow , ultra-narrow , did large-screen LCD splicing can solve these problems.
did Solutions Application Analysis:
1, did for the safety monitoring program areas: surveillance video wall mainly to solve the multi-channel signal centralized control display screen assembly for multi-block splicing , on the same platform , real-time computer images, video images mixed display , which can be single-screen independent screen display can also be achieved through multiple screens stitching software image magnification mosaic display , means flexible , fully meet the needs of the use of video surveillance .
2 , the information display areas: real-time , clearly show the flight information and train schedules, in the rush hour every passenger can choose according to their flow travel time and ease congestion ; weather and other convenient information can be displayed , bring more convenience to the traveling public ; addition, ultra-narrow did TFT LCD Display large screen can also transport these high traffic sites for various advertising and information campaigns , the perfect solution did allow opportunities everywhere !

Clean plant ventilation engineering controls Character LCD Modules

General plant operating environment of harmful substances generated in the generating source will spread through the propagation path of the job, and they therefore operating environment from the generating source control strategies, dissemination and acceptance of the diffusion path by three aspects of exposure to exercise control, Character LCD Module to the extent that Engineering control point of view, it is best to place the occurrence of pollutants polluting substances will be controlled by the nearest treatment, to avoid spread of harmful substances. In order to ensure the safety and health staff and good working environment, should be engineering to improve its operating environment for harmful gases, vapors or dust, etc. The improved operating environment, can be combined with one or two kinds of ways to address hazardous substances exposure hazard.
First, the overall ventilation system
Plant anti-ventilation control mode ventilation primarily as a whole (dilution ventilation) and local exhaust two main forms. Where ventilation is the most basic type of overall ventilation system, its main function is to provide fresh outside air at the workplace, workplace hazardous dilute the concentration of harmful substances and by the flow of air from the outdoors. Therefore the relationship between air and harmful substances, the overall ventilation consists of two basic mechanisms: mixing and displacement. The former so that fresh air and polluted air mixture to achieve dilution effect, the latter is replaced by the contaminated air with fresh air.lcd module  In occupational safety and health regulations, decrees concerning ventilation ventilation devices are set on the overall timing, principles and basic performance requirements vary specifications. However, the air flow pattern in the room, the ventilation performance of the overall impact of a quite significant, and often can not be certainty factor. Indoor geometric state, cubicles, equipment, furnishings, temperature, pressure distribution, intake and exhaust port configuration and human caused deliberately forced ventilation are all factors that influence indoor air.
Overall ventilation in different occasions for different interpretations and calculations. Such as to control indoor air quality (Indoor Air Quality, IAQ) as the goal, the overall ventilation is to provide fresh air to maintain proper temperature and humidity in order to achieve a comfortable purpose; while controlling operating environment is the prerequisite of fresh air dilution when ¸ places polluted air, in order to achieve the purpose of industrial safety and hygiene. As the air from the high pressure to low pressure with the flow characteristics, in order to consider the plant's distribution and airflow poorly ventilated place to avoid the accumulation of harmful substances, generally we all hope to send, mechanical ventilation are implemented and enforced by the air supply, exhaust pipe system design arrangements to dilute the concentration of harmful substances, such as properly designed on the occurrence of a small amount of low concentrations of widespread non-toxic or low toxic pollutants exclude extremely effective. ¸ pollution control effectiveness in accordance with the United States Institute of Industrial Safety and Health ACGIH (American Conference of Governmental Industrial Hygienists) study, the overall ventilation less suitable for the workplace dusts or fumes, which are usually larger because of its toxicity. If you need to use a whole lot of ventilation equipment ventilation and general dust, fume generated a large amount of speed, and therefore vulnerable to localized high concentrations of circumstances, this device can not be controlled. So this is not a ventilation system ventilation design engineers will first consider the use of the design, but this device for generating source pollution harmful or even widespread occurrence of uncertain location of the position, as a very practical in the solution. Consider different sources in different environments required overall ventilation design, we must first consider the calculation of the amount of ventilation, the current overall ventilation ventilation calculation method according to (1) the number of the operator (2) in the workplace space (3) evaporation rate is subject to limits (Threshold Limit Value, TLV) and the minimum Explosive Limit (Lower Explosive Limit, LEL) and other different conditions were estimated.

Overcome cross effects Character LCD Modules

In the dynamic drive mode, to make such a position (i, j) point display, on the need in the i th column and j th row selection voltage is applied at the same time, so that the point of the maximum electric field strength, but this time in addition to (i, j) points, the i-th row and j th row of the remaining points can withstand a certain voltage, these points are called semi-selected point. If the semi-selected point of the effective voltage is greater than the threshold voltage, there appears on the screen should display the contrast decline, which is cross effects. The way to solve the cross effect is the average voltage method, that is, the semi-selected point and non-selected point average of the voltages, an appropriate increase in the non-selection voltage to offset the point on the semi-selected point of the voltage, the semi-selected point on the voltage drop, improve display contrast.
Pixel Control
Pixel by pixel register and a status bit is uniquely determined. There are 16 pixel lcd module registers to control up to 4 × 29 = 116 pixels. We use the LCD from 8 × 8 = 64 pixels. Thus, the pixel data register is sufficient.
Segment Enable
Segment code is enabled by LCDSE registers. Because VIM807-2 is eight 7-segment display, and our choice is 1/3 duty cycle (ie, three common), so by LCDSE register must choose 3 × 8 = 24 segments in order to meet the need, namely complete expression All of the code segment pixels. Of course there will be superfluous, 8 × 9 = 72, because every three commons and 3 above can express 9 pixels.
LCD drive voltage generating
LCD drive voltage is generated in two ways, the internal charge pump method or external resistor ladder network method. Since the Character LCD Module charge pump is in development, in order to reduce design risk, we use a more sophisticated method of external resistor ladder network. Using an external resistor ladder network, VGEN (LCDCON <4>) should be cleared.

Character LCD Modules packaging process description

1 chip test
Microscopy: the material surface for mechanical damage and pitting Ma Hang (lockhill)
Chip size and the size of the electrode meets the technical requirements
Electrode pattern is complete
(2) expansion of tablets
Since the LED chip dicing still tightly packed closely spaced (about 0.1mm), is not conducive to the process after the operation. We use a tablet machine to expand a membrane expansion chip bonding, the LED chip spacing stretched to about 0.6mm. You can also use manual expansion, but it is likely to cause problems of poor and waste chips fall.
3 Dispensing
The corresponding position in the LED bracket point silver plastic or rubber insulation. (For GaAs, SiC conductive substrate, a back electrode red, yellow, green chips, using silver paste for an insulating substrate of sapphire blue, green LED chips, using an insulating adhesive to fix the chip.)
Difficulty lies in the dispensing process control of the amount, in colloidal height, dispensing location are detailed process requirements.
Because silver plastic and rubber insulation in the storage and use are strict requirements, silver plastic wake materials, mixing, use of time is craft must pay attention to. 20x4 lcd display
4 AVAILABLE glue
And dispensing the contrary, prepare gum is prepared Melter first silver plastic coated electrode on the back of the LED, and then put back with a silver plastic of the LED in the LED mounting bracket. Prepare glue dispensing efficiency is much higher than, but not all products are prepared for dispensing process.
5 piece hand-thorn
After the expansion of the LED chip (prepared or not prepared adhesive glue) placed in the thorn piece desk fixture, LED fixture bracket on the bottom, under the microscope with a pin to an LED chip a stab to the appropriate position. Manual and automatic loading rack barbed piece compared to a benefit for ready replacement of different chips, chips for a variety of products that need to be installed.
6 automatic mounting bracket
Automatic loading rack is actually a combination of glue stick (dispensing) and mounting the chip two steps, the first point in the LED bracket silver plastic (plastic insulation), and then use a vacuum suction nozzle from the LED chip mobile location, and then placed in the corresponding bracket position.
Automatic loading rack in the process should be familiar with the main programming device operation, while dipping equipment and installation precision adjustment. The selection of the nozzle try to use bakelite nozzle, to prevent damage to the surface of the LED chip, especially blue, green chips must be bakelite. Because steel mouth will scratch the surface of the chip current spreading layer. lcd module
7 sintering
The purpose is to sinter the silver plastic curing, sintering temperature required to monitor and prevent adverse batch.
Silver plastic sintering temperature is controlled at 150 ℃, sintering time 2 hours. According to the actual situation can be adjusted to 170 ℃, 1 hr.
Plastic insulation generally 150 ℃, 1 hr.
Silver plastic sintering oven according to process requirements must be separated 2 hours (or 1 hour) open replace sintered products, intermediate can not be opened. Sintering oven must not be any other purpose, to prevent contamination.