Presses the anti- sensor
Presses the anti- sensor is according to the semiconducting material pressure anti- effect in on the semiconducting material substrate the component which makes after the proliferation resistance. Its substrate may directly take the survey part, the proliferation resistance inscribes the electric bridge form in the substrate. When the substrate receives the exogenic process has the deformation, various resistance values change, the electric bridge can have the corresponding balanced output. Serves as presses the anti- sensor the substrate (or called diaphragm) the material mainly for the silicon chip and, the silicon chip the silicon which makes for the sensitive material presses the anti- sensor more and more to be valued people's, in particular the gauge pressure and the speed solid state presses the anti- sensor application to be most common. The thermal resistance sensor thermal resistance sensor mainly is changes this characteristic using the resistance value along with the temperature change to survey the temperature and with the temperature related parameter. In the temperature examination precision request quite high situation, this kind of sensor quite is suitable. At present the more widespread thermal resistance material for the platinum, the copper, the nickel and so on, they has the resistance temperature coefficient in a big way, the linearity good, the performance is stable, the application temperature scope width, processes and so on the characteristic easily. Uses in to survey in -200 ℃ ~ +500 ℃ scopes thetemperatures.
The sensor selects the principle base
Sensor in the principle and the structure infinite variety, how acts according to the concrete survey goal, the survey object as well as the survey environment reasonably selects the sensor, the question which is when carries on some quantity survey first must solve. After sensor determination, also was allowed to determine with it necessary measuring technique and the measurement equipment. The measurement result success or failure, is decided in the very great degree to the sensor selects whether reasonably.
1 the basis surveys the object and the survey environment determined the sensor
The type must carry on the concrete surveying work, first must consider uses what kind of principle the sensor, after this need analyzes the various factor can determine. Because, even if is the survey identical physical quantity, also has the many kinds of principles the sensor to be possible to supply to select, which one kind of principle sensor is more appropriate, below then needs according to survey the characteristic and the sensor exploitation conditions consider some concrete questions: Measuring range size; Is measured the position to the sensor volume request; The survey way for the contact type also is the non- contact type; The signal draws out the method, wired or right and wrong contact survey; The sensor origin, the domestic product or imports, whether does the price withstand, or independently develops. After consideration above question can determine selects what kind of type the sensor, then considers the sensor again the concrete performance index.
2 the sensitivity choice is usual
In the sensor linear scope, hoped the sensor keenly goes. Because only the sensitivity high time, with is surveyed the change correspondence the output signal value only then quite to be big, is advantageous to the signal processing. But must pay attention, sensor sensitivity high, with is surveyed the ambient noise which has nothing to do with to be also easy to mix in, also can enlarge by the amplifying system, affects the measuring accuracy. Therefore, requests sensor itself to be supposed to have a higher signal to noise ratio, a reduction harasses the signal from the outside introduction factory. The sensor sensitivity is in the right way tropism. When by the survey is the single vector, moreover is higher to its directive request, then should choose other direction sensitivity small sensors; If by the survey is the multi-dimensional vector, then requests the sensor alternately keenly to go past slightly is better.
3 the frequency-response characteristic
sensor frequency-response characteristic had decided frequency range which surveys, must maintain the not distorted survey condition in the permission frequency range, in fact the sensor response always has surely retards, the hope delay time shorter is better. Sensor frequency response high, observable signalling frequency scope on width, but because comes under the structure characteristic influence, mechanical system inertia bigger, because has the frequency low sensor observable signal the frequency to be lower. In the dynamic survey, should act according to the signal the characteristic (stable state, transient state, is stochastic and so on) the response characteristic, in order to avoid has the error which goes too far.
4 he linear scope
sensor linear scope is refers outputs and inputs the direct ratio the scope. To theoretically says, in this scope, sensitivity maintenance definite value. Sensor linear scope wider, then its measuring range is bigger, and can guarantee the certain measuring accuracy. When chooses the sensor, when the sensor type determined later first will have to look whether its measuring range will answer the purpose. But in fact, any sensor all cannot guarantee the absolute linearity, its linear also is relative. When requests the measuring accuracy quite is low, in the certain scope, may a non-linear erroneous smaller sensor approximately regard as linearly, this can bring enormous convenient to the survey.
5 the stable
sensor uses period of time, its performance maintains the invariable ability to be called the stability. Affects the sensor long-term stability factor besides the sensor itself structure, mainly is the sensor use environment. Therefore, must enable the sensor to have the good stability, the sensor must have to have the stronger environment adaptiveness. In chooses in front of the sensor, should carry on the investigation to its use environment, and according to the concrete use environment choice appropriate sensor, or takes the suitable measure, reduces the environment the influence. The sensor stability has the quota target, after surpasses the lifetime, should recarry on before the use demarcates, determined sensor performance whether does change. In certain requests the sensor to be able the situation which the long-term use but also cannot easily replace or demarcate, selects the sensor stability request is stricter, must be able to undergo the long time the test
6 the precision
precision is a sensor important performance index, it is relates the entire measurement system measuring accuracy an important link. The sensor essence goes past high, its price is more expensive, therefore, sensor precision so long as satisfies the entire measurement system the precision request to be allowed, does not need to elect excessively high. Like this may in satisfy the identical survey goal in many sensors to choose quite cheap and the simple sensor. If the survey goal is the qualitative analysis, selects the repetition precision high sensor then, not suitably selects the absolute size precision high; If is for the quantitative analysis, must obtain the precise observed value, must select the sensor which the precision class can answer the purpose.
stm32/stm8