Roccat's High-performance Optical Key Shaft Appears and Adds a New Style to Vulcan Series

The internal power supply of portable B-ultrasound system is complex. The power supply of external adapter and battery must be converted into the voltage required by the system through DC / DC conversion. In order to reduce the useless consumption of power supply and improve the battery efficiency, the power supply of system motherboard, B-ultrasound control board, LCD and keyboard is powered by switching power supply.Overall design of portable B-ultrasound power supplyFigure 1 is the overall design block diagram of portable B-ultrasound power supply. There are two kinds of power input voltage for portable B-ultrasound: one is the power adapter input, the voltage is 18V, and the other is the battery input, the voltage is 14.4V. It is required to realize the thermal switching between the two voltages, and the system operation will not be affected when switching the voltage, that is, it provides the function of external power supply and battery power supply without delay. It is required to output several voltages such as 12V, 5V, 3.3V and 48V. The specific indicators are 12V / 2.5A, - 12V / 0.5A, 5V / 4A, 3.3v/3a, 48V / 80mA and - 48V / 80mA. It has the function of single key on-off, that is, when there is no power, press the power key to turn on the power; When there is power, press the power key to send a shutdown signal to the control panel, and the upper computer can also shut down through software (i.e. support ATX shutdown command). The power output interface adopts standard computer ATX interface.Figure 1 overall design block diagram of portable B-ultrasound power supplyDesign of power switching circuitThe power switching circuit of portable B-ultrasound is shown in Figure 2. When the external power adapter is connected, the voltage is input to AC 18V, which is divided by VD100 and vd101 diodes, and then applied to pin 3 (in-phase terminal) of n100a (lm193) voltage comparator through R100 and R107. The input voltage of the battery is 14.4V, which is divided by R101 and r108 and added to pin 2 (inverting end) of n100a (lm193) voltage comparator. Since the voltage of pin 3 is higher than that of pin 2, pin 1 of n100a (lm193) outputs high level to turn on triode V100, turn off V101, turn off FET v105 and turn off power_ The in terminal gets the 18V voltage of the external power adapter. When there is no external power adapter, or when the portable B-ultrasound machine cannot use the external power adapter due to sudden power failure of external AC, the voltage of pin 3 of n100a (lm193) is lower than pin 2, and pin 1 of n100a (lm193) outputs low level, so that the triode V100 is off, V101 is on, and the FET v105 is on. The battery voltage passes through the source and drain of the conducting FET v105, power_ The in terminal obtains the 14.4V voltage of the battery, which realizes the thermal switching between the two voltages. Vd102 and vd103 play an isolation role in the circuit, isolating the external power adapter and battery power supply.Figure 2 power switching circuitDesign of single touch switch circuitThe circuit of portable B-ultrasound single touch switch is shown in Figure 3, which is powered by an external adapter or battery_ The in voltage is sent to the FET Q100 for startup, and the other is sent to one end of the touch button power-key2 through r104 and vd104. The other end of the tap button power-key2 is grounded. When the tap button power-key2 is pressed, the base of triode n106 is clamped at the low level, n106 is turned on, N102 is also turned on, FET Q100 is turned on, and power from external adapter or battery_ In voltage passes through the source and drain of Q100 to obtain power voltage to supply power to high and low voltage circuits, and the machine starts up. At the same time of startup, the power voltage passes through the 6V zener diode to turn on the triode n104, and the n104 collector is at the low level to maintain n106 on and maintain the startup state.Fig. 3 single touch switch circuitWhen the portable B-ultrasound machine is in the power on state and the button power-key2 is pressed again, the optocoupler B101 is turned on, the optocoupler secondary is turned on, the four pins of the inverter D101 output a low level to the control panel, and the control panel sends a low-level shutdown command power-off1 to turn on the optocoupler B100, then turn on the triode n103, turn off n104, and the high level of the n104 collector turns off n106, Led to the end of FET Q100 and realized shutdown.When the upper computer sends a high-level shutdown command power-off, it will also turn on the optocoupler B100. The rest process is the same as the shutdown process of the control panel.Design of low voltage power supply circuitThe portable B ultra-low voltage power supply circuit is shown in Figure 4, which is mainly composed of 6 tps5430 of TI company and 1 lm2576 of national semiconductor company. The six tps5430s provide two groups of 12V, 5V and 3.3V voltages, one of which is used to supply power to the main control board of the portable B-ultrasound machine, and the other is used to supply power to the computer in the portable B-ultrasound machine. The two groups are exactly the same, so we only give the power supply schematic diagram of one group. Lm2576 is responsible for generating - 12V voltage to the computer in portable B-ultrasound.Figure 4 low voltage power supply circuitTps5430 has a wide voltage input range of 5.5 36V, continuous 3A current output capacity (peak value of 4A) and conversion efficiency of 95%. 8-pin small patch package, the back of the chip is a metal heat sink, which must be welded to the ground when using. When making PCB package, the heat sink is regarded as the ninth pin. There is no need to connect the heat dissipation device, and good results can be achieved by using the heat dissipation of the circuit board itself, which is especially suitable for the design and use of portable products. Pin 1 of tps5430 is the boot end, which requires an indirect pH of 0.01 between the boot and pin 8 Low ESR capacitance of F. 2. Pin 3 is the empty terminal, and pin 4 VSENSE is the feedback voltage terminal of the regulator, which is connected to the voltage dividing resistance terminal of the output voltage to obtain the feedback of the output voltage. Pin 5 ENA is the power on / off control terminal. When the voltage of this pin is lower than 0.5V, the chip will turn off the power conversion and reduce the power supply current to 18 A. The chip works normally when it is suspended. We do not control this pin, so it is suspended and not connected. Pin 6 is grounded, pin 7 Vin is the power supply terminal, connected to power . A high-quality, low ESR ceramic capacitor is indirectly connected between the power supply and the ground. The 8-pin pH is the source of the internal power FET, and the freewheeling diode and inductor are connected externally. The powerpad end of pin 9 is the heat dissipation metal sheet on the back of the chip, which must be connected to the ground (GND).The output voltage value of tps5430 is determined by the partial voltage value of its 4 pins, and the output voltage Vout = (1.221 (R1 & Themes; 1.221) / r2) v. Wherein, R1 is the resistance above partial voltage and R2 is the resistance below partial voltage. For the design of tps5430, R1 can be taken as 10K , and R2 can be calculated according to the output voltage to be obtained. According to r206 (1.11k), r208 (3.07k) and R210 (5.36k) given in Figure 4, we can calculate that the output voltages are 12.2v, 5.2v and 3.5V respectively, which is slightly higher than the design value by 0.2V. The load is relatively heavy, and the voltage is just right when loaded.N208 (lm2576-12) is a product of American National Semiconductor. Pin 1 is the power supply terminal and connected to power ; Pin 2 is the output end, which is externally connected with freewheeling diode and inductance; Pin 3 is the grounding terminal and pin 5 is the on / off control terminal of the power supply. Due to the output of negative voltage, pins 3 and 5 are not grounded, but connected to the - 12V power supply; Pin 4 is the voltage feedback terminal. We use lm2576-12 with fixed 12V output, so pin 4 is grounded and there is no need to connect the feedback resistor to divide the voltage.Design of high voltage power supply circuitThe portable B ultra-high voltage power supply circuit is shown in Figure 5, using DC / DC converter. Ua3843 is a high-performance, fixed frequency and current mode controller specially used for DC / DC converter applications. It provides designers with a cost-effective solution using the least external components. It is divided into PWM control, cycle current limit, voltage control and so on.Figure 5 48V power supply circuit1 PWM controlPower supplies voltage to pin 7 of N1 (ua3843) through resistor R34, and the sawtooth oscillator formed by external R36 and C33 of pin 4 of N1 and internal circuit starts to work. The PWM pulse is output by pin 6 of N1 to control the on time of MOSFET V9 and determine the output voltage. R37 is used to suppress parasitic oscillation and is usually connected in series near the MOSFET gate. The gate resistance r37 should not be too large, which directly affects the charge and discharge of the input capacitance of the MOSFET by the PWM drive signal, that is, the switching speed of the MOSFET. The induced electromotive force output by the 9th and 10th pins of the secondary of the switching transformer is rectified by vd14 and filtered by C35, L7 and C36 to form a 48V DC output voltage to supply power to the B-ultrasound probe. The induced electromotive force output by the 7th and 6th pins of the secondary of the switching transformer is rectified by vd13 and filtered by C39, L8 and C37 to form a - 48V DC output voltage to supply power to the B-ultrasound probe. Vd12, C34 and R38 form a spike pulse absorption circuit, which is used to suppress the spike pulse with extremely high amplitude generated by the drain of V9 at the moment when the switch turns from on to off. Its principle is: at the moment when V9 is cut off, the spike pulse generated by its drain forms a charging circuit through vd12 and C34. The charging current suppresses the spike pulse within a certain range to avoid V9 being impacted by the spike pulse. After C34 charging, C34 discharges through R38 to prepare for absorbing spike pulse again in the next cycle2 cycle current limitPin 2 feed back is the feedback voltage input terminal. This pin is compared with the reference voltage (generally 2.5V) at the in-phase input terminal of the internal error amplifier to generate the control voltage and control the pulse width. This circuit grounds it and is controlled by pin 1 of the output terminal of the internal error amplifier. The cycle current limit signal of pin 3 determines the width of PWM pulse, that is, the output voltage. R47, r48, R14 and C32 externally connected to pin N1 (ua3843) form a cycle current limiting circuit. In each oscillation cycle, when the peak inductance current of winding 3 5 in the primary of switching power supply pulse transformer L6 reaches the set value, the PWM pulse will be turned off. The set value is determined by the voltage of pin 1 comp terminal of N1 (ua3843) (pin 1 comp is the output terminal of internal error amplifier), Usually, a feedback network is connected between this pin and 2 pins to determine the gain and frequency response of the error amplifier. The cycle current limit control process is as follows: the switch tube is turned on, the inductance current rises, and the sampling voltage V3 rises. When the voltage of pin 3 is greater than 1V, the internal current detection comparator turns over, the internal PWM latch resets, closes the PWM pulse, and is ready to enter the next cycle. In order to eliminate the sharp wave pulse interference of the current limiting circuit, a sharp wave filter circuit is composed of R14 and C32 to ensure that the cycle current limiting function is effective in each oscillation cycle. The current limiting sampling resistance of R47 and r48 determines the maximum output current of the whole switching converter. The maximum output current can be adjusted by changing its resistance.3 voltage controlN1 (ua3843) is a current mode pulse width modulator with two closed-loop controls. The current sampling signal is sent to pin 3 of the in-phase input end of the current detection comparator to form a current closed-loop control, the error voltage is sent to pin 1 of the output end of the internal error amplifier, and its output is sent to the inverting input end of the current detection comparator as a comparison reference to form a voltage closed-loop control. It can be seen that the voltage closed loop and the current closed loop interact. Finally, both of them control the PWM latch through the current detection comparator, that is, control the width of the PWM pulse. The voltage closed-loop control circuit is composed of voltage reference N2 (tl431a), optocoupler B4 (tlp521) and resistors R31, vr7, R12, R32, etc. The current signal output by the optocoupler B4 (tlp521) is converted into a voltage signal and sent to pin 1 of the output terminal of the internal error amplifier. The internal reference of N2 (tl431a) error amplifier is 2.5V. The voltage closed-loop voltage stabilizing control process is as follows: the output voltage rises, the reference terminal VR of tl431a rises, the conduction of TL431 rises, the conduction of optocoupler B4 (tlp521) rises, the voltage of pin 1 drops, the turnover of internal current detection comparator is advanced, the reset of internal PWM latch is advanced, the PWM pulse becomes narrow and the output voltage becomes low, so as to stabilize the output voltage. High voltage output voltage Vout = (1 R31 / (R12 vr7)) VREF. By adjusting the value of potentiometer vr7, the output can be adjusted to 48V, and the adjustment range is 31 & times; 2.5=77.5V115&TImes; 2.5=32VepilogueThis paper introduces the design of portable B-ultrasound power supply, including power switching

Why is arc suppression coil called arc suppression coil?Why is arc suppression coil called arc suppression coil? If you want to know why you call it so, let's talk slowly for you.The reason why it is called this name is that we first look at the word "coil". It is an inductive coil with iron core, which is applied in the neutral grounding system. The power system transmission line is grounded through arc suppression coil, which is a kind of small current grounding system, so it is called "coil".Arc suppression coil is so called because it can play the role of "arc suppression". Its arc suppression principle is that when the line is short circuited and grounded and the current is more than 30a, the voltage generated by the discharge gap will increase by 2.5-3 times the line voltage. When the arc suppression device is installed at the neutral point of the transformer, the voltage at the discharge can not increase under the damping effect of the inductance coil, so as to reduce the discharge current and reduce the current, It also plays the role of arc suppression. When the magnitude of the two currents is less than the minimum current of the arc, the arc will not occur and there will be no resonance overvoltage. According to the regulations of overvoltage protection and insulation coordination of AC electrical devices issued by the former Ministry of electric power industry, when the single-phase grounding fault capacitance current of 3-66KV system exceeds 10a, the grounding mode of arc suppression device shall be adopted.It is mainly used in power supply industry, power plants, metallurgy, mining, coal, papermaking, petrochemical and other large factories and mining enterprises. The applicable voltage level is 6 66kV. It is an ideal replacement product for old arc suppression coils. At the same time, it is also the preferred supporting product for grounding compensation and line selection devices of new substations.In fact, why is it called arc suppression coil? As the name suggests, it is an inductive coil to effectively prevent arc grounding of power system, eliminate grounding fault and improve power supply quality.Complete set of automatic tracking compensation device for arc suppression coil

What does integrated gate commutated thyristor (IGCT) meanIntegrated Gate Commutated Thyristors IGCT (Integrated Gate Commutated Thyristors) is a new type of power semiconductor device used in giant power electronic devices published in 1996. IGCT is a new high-power semiconductor switching device based on GTO structure, using integrated gate structure for gate hard drive, using buffer layer structure and anode transparent emitter technology. It has the on state characteristics of thyristor and the switching characteristics of transistor. Due to the buffer structure and shallow emitter technology, the dynamic loss is reduced by about 50%. In addition, this kind of device also integrates a freewheeling diode with good dynamic characteristics on one chip, so as to organically combine the low on-state voltage drop of thyristor, high blocking voltage and the stable switching characteristics of transistor in its unique wayIGCT makes great progress in power, reliability, switching speed, efficiency, cost, weight and volume, and brings a new leap to the complete set of power electronics devices. IGCT integrates GTO chip with anti parallel diode and gate drive circuit, and then connects with its gate driver in a low inductance way. It combines the advantages of stable turn-off ability of transistor and low on state loss of thyristor, gives full play to the performance of thyristor in the on stage, and presents the characteristics of transistor in the off stage. IGCT has the characteristics of large current, high voltage, high switching frequency, high reliability, compact structure, low loss, low manufacturing cost and high yield. GTO with thyristor technology is a common high-power switching device. It has higher performance in cut-off voltage than IGBT with transistor technology. However, the widely used standard GTO driving technology causes uneven turn-on and turn-off process, requiring high-cost DV / dt and di / dt absorption circuits and high-power gate driving units, resulting in reduced reliability and high price, It is also not conducive to series connection. However, before the maturity of high-power MCT technology, IGCT has become the preferred scheme of high-voltage, high-power and low-frequency AC.The figure below shows the outline of asymmetric IGCTIGCT is similar to GTO. It is also a four layer three terminal device. The GCT is composed of thousands of GCTs. The anode and gate are shared, while the cathode are connected in parallel. The important difference from GTO is that there is a buffer layer inside the IGCT anode, and the transparent (permeable) anode is used to replace the short-circuit anode of GTO. The on mechanism is exactly the same as that of GTO, but the off mechanism is completely different from that of GTO. During the off process of IGCT, GCT can instantly change from on to blocking state, become a PNP transistor and then turn off, so it has no external Du / dt limit; The GTO must be converted through an intermediate unstable state that is neither on nor off (i.e. "GTO area"), so GTO needs a large absorption circuit to suppress the change rate Du / dt of the re applied voltage. The equivalent circuit of IGCT in blocking state can be considered as the series connection of a base open circuit, low gain PNP transistor and gate power supply.The IGCT trigger power is small. The trigger and state monitoring circuit and the IGCT tube core can be made into a whole, and the trigger signal and working state signal can be input and output through two optical fibers. IGCT integrates the advantages of GTO technology and modern power transistor IGBT. Using the key technology that high-power shutdown devices can be simply and reliably connected in series, IGCT has no real rival in the medium and high voltage field and the high-power application field with power of 0.5mva 100mva.The following table shows the performance comparison of IGBT, GTO and IGCT power devices:The advantages of low loss and fast switching of IGCT ensure that it can be reliably and efficiently used in 300 KVA 10MVA converter without series or parallel. When connected in series, the inverter power can be extended to 100mva. Although the high-power IGBT module has some excellent characteristics, such as active control of di / dt and DV / DT, active clamping, easy to realize short-circuit current protection and active protection, etc. However, due to the disadvantages of high conduction loss, open circuit after damage and no long-term reliable operation data, the practical application of high-power IGBT module in high-power low-frequency converter is limited. Therefore, IGCT will become the preferred power device of high power and high voltage frequency converter.

At CES 2017, we saw countless game peripherals, and ASUS once again expanded its "player country" (Rog) product line, and launched peripherals such as microphone, game mouse and high-end router. First, let's introduce the Rog Strix Magnus microphone, which is specially built for the live streaming media market and has a compact shape. In terms of function, the microphone includes three groups of studio level capacitive pickups, and can reduce the ambient sound.Rog Strix Magnus microphoneIt is worth mentioning that the microphone can also be used as an external USB hub and supports aura RGB lighting effect.Rog gladius II game mouseRog gladius II is an optical mouse equipped with aura sync RGB light effect and OMRON button. Users can adjust DPI in real time through two buttons (one button is behind the wheel and the other is at the thumb position, so as to select the best accuracy when aiming).ASUS claims that its buttons can withstand 50 million clicks and support easy replacement. This can not only prolong the service life of the device, but also enable players to adjust the feel on demand.New Rog Strix evolve mouseThe top cover of the new Rog Strix evolve mouse is divided into four pieces, which is very in line with the ergonomic design. Left handed players will appreciate this replaceable top cover design.In addition, ASUS also launched a new Rog Strix impact mouse, which adopts a lightweight design, which is suitable for users who like dexterous, accurate and simple control.It should be noted that both Strix evolve and Strix impact support aura sync RGB light control and OMRON buttons.Rog gx970 mouseThe mouse adopts the design of switchable side panel, and the user can choose between two side keys and ten side keys (these two side plates are provided in the packaging box at the same time). Through the supporting software, users can also specify functions for keys and store them in onboard ROM.The Rog gx970 mouse also supports counterweight adjustment, with a maximum tracking speed of 12000 DPI.Rog rapture gt-ac5300 wireless routerFinally, Rog rapture gt-ac5300 tri band wireless router is introduced. In addition, it also provides 8 & Themes; Gigabit Ethernet port.The route adopts an unspecified 1.8GHz quad core processor, and the gaming center software can be used as a good tool to quickly monitor and adjust network traffic (such as optimizing Ping value for popular games).In addition, ASUS also launched a gt-ac5300 wireless router, which provides two "game specific" LAN ports and supports functions such as GameBoost (which can optimize the network communication of the game).

Excel is the most magical and important software in MS office series. Stop foolishly clicking around with the mouse! Use these 10 basic skills to improve work efficiency and get twice the result with half the effort1. "Ctrl PgDn / PgUp" conversion worksheet2. Use "Ctrl directional character" to quickly convert cellsOf course, you can just press the direction key and move it grid by grid. But if you want to quickly convert cells, long press "Ctrl" before pressing the direction key, and you can achieve the effect of "key step like flying" in an instant.3. Skillfully use the "shift" key to select dataUse "Ctrl Shift" to select cells vertically and horizontally, so as to select the area you want.4. Double click auto fill dataTo automatically fill in the same column with functions, don't long press the mouse and try to pull down to the last column - what if your table has hundreds of rows? Double click the lower right cross of the calculated cell to easily fill in the complete column of data.5. Let the three shortcut keys quickly unify the data formatDo you want the data to appear to two decimal places? Use Ctrl Shift!.How much is the unit? Use Ctrl Shift $.What percentage do you want? Use Ctrl Shift%.Isn't it tired to click the mouse so many times? Use these three shortcut keys to realize the uniform format of the speed of light, and the latter two should be particularly easy to remember.6. Lock the cell with F4When filling data according to functions in Excel, sometimes you want the cells you reference to change when they drop down, and sometimes you don't think so. When you want to "absolute reference" - that is, lock the cell, you must add a $sign before the row and column. Want to type these dollar symbols manually? It's crazy... How much time will it waste, you know? In fact, there is a simple technique, that is, after you select the cell, press F4 to enter the dollar symbol and lock it; If you continue to press F4, you will cycle back one by one: Lock cells, lock numbers, lock uppercase letters, and unlock.7. Summarize statistics with countif and SUMIFCountif is a function algorithm that counts the number of cells that meet established conditions within a specific range. The first parameter is the range you want to count; The second parameter is your condition. For example: = countif (A1: a10,1), that is, within the range of A1: A10, the cell content is 1 number.COUNTIF(range,criteria)The SUMIF function is used to sum several cells, ranges, or references based on specified conditions. Below is the total number of views we are calculating for each author. In terms of scope, the format of the author's name is inconsistent, but the total number is the same. Column B corresponds to the name of the corresponding author, and column e corresponds to the number of views of each author's work.SUMIF(range,criteria,sum range)8. Use vlookup to find the data you wantVlookup is a search function by column, and finally returns the value corresponding to the required query column order of the column. Here we can see a data table. The first column is the ranking of law schools. We can use vlookup to create a query of the top five schools.VLOOKUP(lookup value,data range,column number,type)The first parameter needs to enter the value to find. Here we use the number of rankings we need. The second parameter here, enter the region we want to find (absolute reference). For the third parameter, you need to enter the number of columns of the returned data in the search area. For the fourth parameter, because we want to find it accurately, enter "false" or "0".9. Merge cells with "&"We now have a column of last names and a column of names. We can use the "&" symbol to create a column of data that combines last names and first names. In Excel, "&" refers to merging two or more texts. Don't forget to type a space between your last name and first name. Your function should look like this format = [first name] & "& [last name].10. Generate random number with rand functionYou can use the rand() function to generate a single random number, which is less than 1 but greater than or equal to 0. Just leave the parentheses empty without typing any parameters. The new random number will be regenerated with the update of the workbook. You can also press F9 to recalculate the worksheet to update the random number, but remember to be careful when operating.RAND()

Speaker unit for home theater set Speaker unit refers to the situation of speakers (commonly known as speakers) used in the set speaker of home theater. It usually refers to the size, shape and material of speakers, which mainly determine the characteristics of speakers.Most of the structural forms of subwoofer are cone basin type, and a few are flat plate type. There are many kinds of subwoofer diaphragm, including aluminum alloy diaphragm, aluminum magnesium alloy diaphragm, ceramic diaphragm, carbon fiber diaphragm, bulletproof cloth diaphragm, glass fiber diaphragm, propylene diaphragm, paper diaphragm, etc. Bass unit, which determines the sound characteristics of the speaker, is relatively important to choose. The bass unit with aluminum alloy diaphragm and glass fiber diaphragm generally has small caliber and large bearing power, while the bass unit with reinforced paper basin and glass fiber diaphragm has accurate timbre and good overall balance when replaying music. The paper basin has natural sound, low cost, good rigidity, light material and high sensitivity. The disadvantages are poor moisture resistance and difficult to control the consistency during manufacturing. However, the paper basin is made everywhere in the top hifi system because the sound output is very average and the reducibility is good. Bulletproof cloth, with wide frequency response and low distortion, is the first choice for those who love strong bass. Its disadvantages are high cost, complex production process, low sensitivity and poor light music effect. The wool woven basin has a soft texture. It performs very well for soft music and light music, but the bass effect is poor and lacks strength and shock. PP (polypropylene) basin, which is widely popular in high-grade speakers, has good consistency, low distortion and commendable performance in all aspects. In addition, fiber diaphragm and composite diaphragm are rarely used in popular speakers due to their high price.Generally speaking, as long as the frequency response curve of the mid-range loudspeaker is flat, the effective frequency response range is greater than the width of the playback frequency band it undertakes in the system, and the impedance is consistent with the sensitivity and low-frequency unit. Alto units generally have cone basin and ball top. But its size and power are larger than the tweeter and suitable for playing medium audio. The diaphragms of the Alto unit are mainly soft materials such as paper basin and silk film, and occasionally there are a small amount of alloy ball top diaphragms.The function of high-frequency loudspeaker in speaker is to replay various high-frequency signals, and its working frequency is generally above 2K. The overall requirement for high-frequency loudspeaker is that it can have flat frequency response, high-frequency playback upper limit as much as possible and certain power bearing capacity to meet the requirements in the effective working frequency band. Its structural forms mainly include horn type, cone basin type, ball top type and aluminum belt type. At present, the most common domestic speaker and small monitoring speaker is ball top type. The ball top tweeter is divided into hard ball top and soft ball top from the material. The diaphragm materials of hard top treble include aluminum alloy, titanium alloy, magnesium alloy, titanium alloy composite film, glass film, diamond film and so on. The treble played back by the hard top treble unit has bright timbre and metal feeling. It is suitable for playing pop music, film music and effect music. The production of excellent aluminum alloy and titanium alloy composite film dome tweeter can also better express classical music and human voice. The vibrating film materials of the soft ball top tweeter are silk film, silk thread film, rubber film and bulletproof cloth film. The soft dome tweeter unit is flexible and relaxed when replaying music, and has good natural expressiveness. It is particularly handy when performing classical music, human voice and other music with standard listening concepts. In recent years, the playback upper limit frequency of silk film and silk film ball tenor has reached 40KHz. Theoretically, the upper limit frequency of tweeter unit should at least reach 20kHz, the higher the better. However, the unit with excellent high frequency upper limit is also more expensive.Naturally, the larger the speaker size, the better. Large caliber bass speakers can perform better in the low-frequency part, which can be selected in the purchase. Most of the subwoofers in ordinary home cinemas are between 5 and 12 inches. The speakers made of high-performance speakers also mean lower transient distortion and better sound quality.

How the mouse worksWorking mode refers to the working principle or mode adopted by the mouse. The common working modes of mouse include roller type and photoelectric type.Roller type Roller type is the most common mouse. Its biggest feature in appearance is that there is a positioning roller in the groove at the bottom to move the cursor. According to the working principle, the roller mouse can be divided into the first generation of pure mechanical type and the second generation of optomechanical type (hereinafter referred to as optomechanical type). (1) Pure mechanical Pure mechanical mouse is rarely seen in the world now. There is a rolling ball at the bottom of it. When the mouse is pushed, the rolling ball will constantly touch the small roller next to it to produce pulses of different intensities. Through this chain effect, the computer can calculate the correct position of the cursor. (2) Optical mechanical type This is commonly referred to as the mechanical mouse, which is a combination of photoelectric and mechanical mouse. Its principle is that there are two mutually perpendicular transmission shafts close to the rolling rubber ball, and there is a grating wheel on the shaft. The two sides of the grating wheel correspond to light-emitting diodes and photosensitive triodes. When the mouse moves, the rubber ball drives the two transmission shafts to rotate, and the time grid wheel is also rotating. The photosensitive triode is intermittently blocked by the grating wheel when receiving the light emitted by the light-emitting diode, so as to generate pulse signals, which are received by the CPU after being processed by the chip inside the mouse. The number and frequency of signals correspond to the distance and speed on the screen.Photoelectric type Photoelectric mouse products can be divided into two generations according to their age and technology. Their common feature is that there is no mouse ball that must be used for mechanical mouse. The first generation of photoelectric mouse judged the signal by the light interrupter. The most remarkable feature is that a special reflector needs to be used as the pad when the mouse moves. The main feature of this pad is the tiny black and white dots. The reason is that at the bottom of the photoelectric mouse, there is a light-emitting diode and two mutually perpendicular photosensitive tubes. When the light-emitting diode irradiates the white spot and black spot, it will produce two states of refraction and non refraction, and the photosensitive tube will produce corresponding signals after processing these two states. So that the computer can respond. Once it leaves the pad, the photoelectric mouse can't be used. At present, the photoelectric mouse products on the market are the second generation of photoelectric mouse. The principle of the second generation photoelectric mouse is actually very simple: it uses the optical eye technology, which is a digital photoelectric technology. Compared with the previous mechanical mouse, it is a completely new technical breakthrough.The photoelectric sensing device transmits and receives every second to realize accurate and fast positioning and command transmission. Another advantage is that the optical eye technology abandons the shackles of the previous generation of optical mouse, which requires a special mouse board, and can be used on any non reflective and opaque object surface. The biggest advantage of using it is that it does not need to clean the mouse ball as often as the mechanical mouse, and its resolution and refresh rate are much higher than the mechanical mouse. The positioning of high-grade optical mouse is very accurate. Generally speaking, the start of photoelectric mouse is very high, that is to say, most photoelectric mice are ergonomically designed, so that consumers can have a more appropriate reason for consumption.Fingerprint mouse Fingerprint mouse is a special function mouse with fingerprint acquisition and identification functions. It is suitable for individuals, offices, enterprises and other industries and enterprises with high security requirements. Because of its high price, it is not suitable for ordinary individual users.With the popularization of office automation, our daily work can not leave the computer. Each computer user will encrypt their important data and files to protect their own confidentiality or privacy. But this traditional password has obvious disadvantages, that is, the password is easy to be forgotten, the password is easy to be peeped and obtained by those with ulterior motives, the password is easy to be cracked, and so on. To solve this problem, the computer security management system has a new encryption method, fingerprint identification encryption. A fingerprint acquisition sensor is integrated on the fingerprint mouse. Each time the computer is turned on, the user puts a specific finger (generally thumb) on the sensor window, and the computer automatically scans it, and then compares it with the fingerprint stored in the system, so that it can be easily and safely connected to the host to start working, so as not to worry about illegal entry of irrelevant personnel. The fingerprint mouse can be used when logging in and restoring screen protection, or when decompressing encrypted files. Its main indicators in terms of security are self rejection rate, others' tolerance rate and fingerprint image transmission rate (this parameter determines the speed of fingerprint acquisition and identification). At present, the mainstream products have reached a very low error rate in this self rejection rate and others' tolerance rate, and the fingerprint image transmission rate can reach more than ten frames per second.

1. IntroductionThis document shows how to easily build an interesting pointing device step by step: wireless tilt mouse, that is, you can control the mouse through the on-line tilt board itself and the computer screen cursor. Analog data from three-dimensional accelerometer and two keys are obtained, converted and broadcast by using standard XBee module to transmit ZigBee protocol. At the receiving end, another XBee module is connected to the computer through easyusb module, allowing the two files to be stored in the same interface and communicated?? S, seen as a common mass storage device PC. In practice, there is no need to install any application on the computer: the software, communication with XBee and analog mouse function is the residents' internal easyusb itself, which is automatically recognized by the computer as a USB drive. The accelerometer / transmitter circuit board is powered by AA batteries. The goal of the project is to become an open source hardware / software platform that can accelerate learning about access and use? Data, configure and manage customized XBee module USB peripherals. All hardware?? Schematic diagram and software source code are well annotated with project files. In order to design a fast and easy to build platform, only breakthrough boards and modular components are used. Specific skills such as patch welding and embedded software programming are not necessary.2. Construction steps2.1.1 hardware connection - connect the board: welding wire according to the hardware schematic diagram and wiring diagram. Please note that the XBee modules of the chip antenna should not be welded: they are connected to the appropriate XBee browser regulated socket.2.1.2 Transmitter configuration - insert the XBee module in the slot on the receiver and the USB cable into the PC. The waiting device is automatically installed as a common USB mass storage device.-Copy to USB device XBee_ Config.exe console. Run XBee_ Config.exe console, press t to configure as the transmitter XBee module. Press ESC to exit.-Take off the XBee module from the receiver socket and place it in the transmitter socket. 2.1.3 Receiver configuration - connect the socket on the receiver to another XBee module. Run XBee_ Config.exe console, press R to configure to receive XBee module. Press ESC to exit.-Copy the tiltmouse.exe scheme to the USB device. Wireless mouse transmitter and receiver tilt is complete! In order to use it, just run tiltmouse.exe on the receiver, the transmitter on the console and the battery of the plug. Console, better than analog mouse? In addition to the function, also print the data obtained from each acceleration on the screen? S axis and button.2.2 schematic diagram

Recently, Xiaomi has put on the shelf the Xiaobai intelligent video doorbell D1 set developed and designed by chuangmi technology, which officially announced that Xiaomi's smart home product array has added another capable player.Xiaobai intelligent video doorbell D1 set costs 299 yuan. It has a variety of practical functions such as 1080p ultra clear camera, high-capacity rechargeable lithium battery, AI face recognition, active viewing of real-time video, etc. now it will also give 7-day free cloud storage with a service life of one year.Xiaobai smart video doorbell D1 has successfully entered Xiaomi smart home product array. Xiaobai smart video doorbell D1 can be controlled through Mijia app and can be linked with Xiaomi products such as Xiaomi TV and Xiaomi touch screen speaker to realize interoperability. If users have one or more products at home, they can connect with Xiaobai intelligent video doorbell D1 through relevant products to check the situation outside the door in real time, making life more convenient and comfortable.Xiaobai intelligent video doorbell D1 package is composed of Xiaobai intelligent video doorbell D1 and Xiaobai doorbell receiver. Xiaobai intelligent video doorbell D1 adopts strong adhesive backing, which can be installed on the door easily with one touch, which is not only convenient to operate, but also more beautiful. At the same time, in order to prevent external force damage, when it is detected that the doorbell is forcibly removed from the base, the video will be automatically recorded immediately and an alarm will be sent to notify the user.According to the official data of Xiaomi Youpin, Xiaobai intelligent video doorbell D1 set with built-in 5200mAh high-capacity rechargeable lithium battery can be used for up to 60 days in standard mode and 210 days in power saving mode. While having higher endurance, the power-saving mode of the doorbell only reduces the function of actively viewing the live broadcast compared with the standard mode, and still supports the functions of detecting video recording, message push, infrared night vision and passive viewing the live broadcast.Let's talk about the function. Xiaobai intelligent video doorbell D1 has PIR human body infrared sensing change, and also adds the "real-time video viewing" function, so that users don't need to wait until there is a change at the door to receive push. Users can choose to view the real-time situation outside the door at any time, and have a better understanding of family safety. In addition, there are many functions such as remote audio and video call function, ultra wide-angle HD camera and infrared night vision function. In comparison with similar products, Xiaobai intelligent video doorbell D1 package also won with significant advantages.The 7-day free cloud storage function presented by Xiaobai intelligent video doorbell D1 package can automatically store the videos of the last 7 days and automatically cycle coverage. Even if users need to go out for travel or business trip, they can view the video records of recent visitors anytime and anywhere. However, it should be noted that after the 1-year time limit for gift arrives, the 7-day free cloud storage function will be automatically reduced to 3-day free cloud storage without renewal. Therefore, even after the time limit for gift arrives, users can continue to use the cloud storage function for free.Compared with similar products, Xiaobai intelligent video doorbell D1 considers many more humanized functions while considering how to maintain user safety.Xiaobai intelligent video doorbell D1 humanized adds AI face recognition function, which can not only confirm the identity of visitors, but also mark the identity, count visitor data and other functions. Users can quickly screen relatives, friends and strangers among visitors by marking their identity, and count the recent visits of visitors to determine whether they pose a threat to users' security.Xiaobai intelligent video doorbell D1 also has voice change intercom function. For special groups such as lonely people, Xiaobai intelligent video doorbell D1 fully considers how to help users protect privacy. When visitors arrive, users can also choose to change their voice into voices of different ages and genders to communicate with people outside the door to better protect their own safety.In addition, Xiaobai intelligent video doorbell D1 also has a small colored egg. In terms of chips, Xiaobai intelligent video doorbell D1 selects Beijing Junzheng t21z chip. Junzheng t21z chip has ultra-high efficiency, supports smart H.264 coding engine and full real-time performance; Support low-power fast start and front-end false alarm filtering algorithm; It supports 2 million HD resolution and adopts the new generation ISP noise reduction technology. The power consumption of a typical 2 million coding scenario chip is less than 300MW, which is very suitable for a cost-effective low-power camera scheme, helping enterprises and users not only enjoy ultra-high performance, but also save a lot of additional investment.In general, Xiaobai intelligent video doorbell D1 set is a product full of "Xiaomi" characteristics. While the price is close to the people, it has not made any compromise on performance. From the ingenious thinking on the design of Xiaomi intelligent video doorbell, it can be seen that chuangmi technology is not only satisfied with building Xiaobai intelligent video doorbell D1 package into a cost-effective product, but also designs with a heart of thinking for users. Therefore, the Xiaobai intelligent video doorbell D1 set finally polished has successfully become a product that not only has high cost performance, but also successfully meets the needs of users.Original title: real time control of the dynamics in front of the door. Xiaomi has a new Xiaobai intelligent video doorbell D1 setThe source of the article: [WeChat official account: Beijing Jun Zheng] welcome to add attention! Please indicate the source of the article.

On March 19, the new stone sweeping robot T6 was officially put on the shelves today. Xiaomi crowdfunding was priced at 2799 yuan. In addition to establishing a province of 200 yuan, participants in crowdfunding were also given a accessories package worth 354 yuan.The stone sweeping robot T6 focuses on four highlights, namely "strict selection of well-known components and 2-year warranty of the whole machine", "New Map Management 3.0", "new noise reduction design" and "new sweeping and dragging experience".The T6 core processor of the stone sweeping robot adopts the flagship chip R16 of allwinner series, a cutting-edge brand in the industry. Ti digital signal processor comes from Texas Instruments, an old semiconductor brand. MCU microprocessor selects st Italian semiconductor, the largest semiconductor brand in the world.As the "eye" of the sweeping robot, the LDS navigation system of the stone sweeping robot T6 has upgraded the new generation of laser mapping algorithm, which brings faster, more stable and more accurate mapping ability, and can automatically identify the room and clean the room like a person.In addition, the newly upgraded rock navigation path planning of stone sweeping robot T6 is more intelligent than the previous generation. Based on the principle of long side priority and proximity, the stone sweeping robot T6 sweeps faster in long and narrow areas, does not detour, does not take the wrong road, and the cleaning efficiency is improved by 20%.Thanks to the above two intelligent upgrades, the map Management 3.0 system of stone sweeping robot T6 can accurately remember the user's home map after the first cleaning, provide users with more personalized cleaning operations, support selected area cleaning, zoned cleaning and virtual wall restricted area setting, and sweep wherever you want.The stone sweeping robot T6 redesigned and optimized five noise reduction units to achieve low noise under large suction. The new 30.5mm motor is adopted, which reduces the speed (improves the torque) compared with the previous generation products, so as to reduce the running noise. At the same time, the motor vibration and gear design are optimized, and the sound insulation cotton and noise reduction air screen are filled near the motor to greatly reduce the noise caused by the robot. In general, under the condition of ensuring high suction, the sound power of stone sweeping robot T6 is reduced by 50% compared with the previous generation.It is worth mentioning that in the sweeping system of stone sweeping robot T6, stone has made three optimizations for three practical problems of users:1. Aiming at the problem that hair is easy to be wrapped at both ends of the main brush, the stone sweeping robot T6 innovatively launched a removable main brush, so that consumers can easily remove the whole mass of hair in only three steps. At the same time, the bristles of the main brush are made of DuPontTM Zytel, an international first-line brand, which has stronger cleaning power, flexibility and durability, and is more gentle to the floor.2. In view of the trouble of washing mops by hand, the stone sweeping robot T6 innovatively launched a disposable mop that is ready to use and throw (10 pieces are given away with the package). Disposable mop adopts mop support plate and Velcro design, which can be easily installed or torn off, and truly realizes that users do not need dirty hands.3. Aiming at the problem of different wet mop requirements, the water tank of stone sweeping robot T6 has added adjustable gears, and the two gears of water can meet the needs of different scenes - for example, daily cleaning can adjust a small amount of water, which will not cause long-term moisture on the ground; If there are strong stains on the ground (such as soy sauce drinks, etc.), it is necessary to increase the water tank to let the water dissolve the stains.In addition, the stone sweeping robot T6 continues 5200mAh large battery, 2000Pa large suction, 2cm super obstacle crossing, 14 types of sensors, etc,According to the total number of AVC Omni channel sales, from 2016 to 2018, the compound growth rate of retail sales of floor sweeping robots in China reached 49%, which was much higher than that of other household appliances. In 2018, the retail sales scale was 7.8 billion yuan and the retail sales scale was 6.05 million units. According to the data of market research institutions, more than 80% of domestic laser sweeping robot products come from stone technology.