08濕度傳感器系統(tǒng)畢業(yè)論文中英文資料外文翻譯文獻-文庫吧在線文庫
【正文】 educed to a minimum. The following applies: Thermal effects (3), (4), and (5) Because the total thermal mass of the humidity measurement system (sensor + housing) has a significant effect on its response time, the total thermal mass must be kept as low as possible. The greater the total thermal mass, the more inert the measurement system bees thermally and its response time, which is temperaturedependent, increases. In order to 吉林農(nóng)業(yè)大學(xué)本科畢業(yè)設(shè)計 5 prevent measurement errors, the sensor should not be mounted in the vicinity of heatgenerating ponents. 4 Summary – what should be taken into account when designing a humidity measurement system In order to achieve errorfree operation of a humiditymeasurement system with response times as short as possible, the following points should be taken into account especially for the selection of the sensor and for the design of the system. ? The selection of the humidity sensor element. It should ● be as small as possible, ● have a thermal mass that is as low as possible, ● work with a polymer, which exhibits minimal fluctuations in measured values during the time span 2(cf. Fig. 1)。 little diffusion! ? The sensor should be decoupled thermally as much as possible from other ponents, so that the response characteristics of the sensor are not negatively affected by the thermal inertia of the entire system.(., its own printed circuit board for the humidity sensor, structurally partitioning the housing to create a small volume for the humidity sensor, see Fig. 3) Fig. 3: Mounting example for Sensirion sensors SHT11 and SHT15 with slits for thermal decoupling ? The sensor should not be mounted in the vicinity of heat sources. If it was, measured 吉林農(nóng)業(yè)大學(xué)本科畢業(yè)設(shè)計 6 temperature would increase and measured humidity decrease. 5 Design proposal The challenge is to realize a system that operates cleanly by optimally taking into account all of the points in section 4. The already calibrated SMD humidity sensors SHT11 and SHT15 from Sensirion are the ideal solution. For optimum integration of the sensors in a measurement system, Sensirion AG has also developed a filter cap as an adapter aid, which takes into account as much as possible the points in section 4 and also protects the sensor against contaminants with a filter membrane. Fig. 4 shows schematically how the sensors can be ideally integrated into a housing wall by means of the filter cap SF1. Fig. 4: Filter cap for SHT11 and SHT15 In addition to the advantages mentioned above, there is also the option of building an IP67pat
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