Sensor is a detection device, can feel the measured information, and can feel the information, according to certain laws transformed into electrical signals or other required forms of information output to meet the requirements of information transmission, processing, storage, display, recording and control, etc., the characteristics of the sensor include: miniaturisation, digitisation, intelligence, multifunctionality, systematisation, networking. It is the first link to achieve automatic detection and automatic control, it is no exaggeration to say, from the vastness of space, to the vastness of the ocean, to a variety of complex engineering systems, almost every modern project, are inseparable from a variety of sensors. Then the next Xianjie net editor for you to introduce the working principle of the sensor, application, application of common problems and solutions, classification, main functions, selection methods and top ten brands.

1, the sensor is generally composed of sensitive components, conversion components, conversion circuits, auxiliary power supply consists of four parts, in which the sensitive components directly receive the measurement, for the output of the measured physical signals, sensitive components mainly include heat-sensitive, light-sensitive, humidity-sensitive, gas-sensitive, force-sensitive, acoustic, magnetic, colour-sensitive, taste-sensitive, radioactivity-sensitive and so on the top ten categories; conversion components used to convert the output of the sensitive components of the physical signals into electrical signals;

2. The conversion circuit is used to amplify and modulate the output signal of the conversion element; the auxiliary power supply is used to provide energy for the system (mainly the sensitive element and the conversion element).

gravity sensors, in Need for Speed, Daily Runner and other games have a near-perfect embodiment; acceleration sensors, such as mobile phone shake function is the acceleration of the mobile phone to sense; light sensors, such as mobile phones, automatic dimming function; distance sensors, such as answering a call when the phone away from the ear screen becomes brighter, the phone closer to the ear screen becomes black, mobile phones in the There are countless sensors in mobile phones, and many functions are realised by using sensors, so I won't list them all;

sensors in daily life also has a wide range of applications, common such as: automatic doors, through the human body infrared microwave sensing to control its switching state; smoke alarms, through the concentration of smoke sensing to achieve the purpose of the alarm; electronic scales, through the mechanics of the sensors to measure the weight of the person or other items; water alarm, temperature alarm, humidity alarm, etc., are also the use of the sensor to complete the their functions.

Continuous printing when the print position is inconsistent, mainly due to paper jitter in the channel and the paper itself gap inconsistency, resulting in the sensor to detect the instability of the waveform, thus making the positioning of the continuous printing is not accurate. Solution: to solve the problem of paper jitter in the channel (especially small labels): by increasing the buffer mechanism, or increase similar to the Zebra Z4M sensor compression mechanism to solve. To solve the problem of inconsistent label gap itself: by changing the firmware program, change the positioning of the label, the use of the label gap along the back edge of the positioning can minimise the impact of gap errors;

As the paper in the channel changes the distance relative to the transmission sensor and reflective receiver between the design of the distance change range is large, resulting in a large rate of change of the luminous force, the paper's transmittance of light intensity changes, is the main reason for the transmission sensor level instability, in the design process, we must take into account the detection range of the sensor and the media in the channel jitter, so that because of media jitter caused by the output voltage change is too large, resulting in the detection of Failure or failure to detect, such as paper in the channel up and down the distance of 1 mm, transmission sensors or reflective receiver between the design distance of at least 5 mm, the design of electrical parameters should at least ensure that the intensity of light transmission of the paper in the 10% range of changes in the transmittance of the sensor level in the range of the discriminatory level (no paper and liner voltage difference of more than 1V);

Thermal paper on the thermal material on the infrared light reflection is very strong, resulting in the sensor can not identify the thermal printing of the black mark, as we use the sensor for the infrared light detector device, and thermal paper on the infrared light reflection is very strong, resulting in the detection of other parts of the media and the marking of the part of the reflectivity of the difference greatly reduced, resulting in the mark can not be identified properly, therefore, the selection and use of sensors should be fully taken into account during the process The impact of different media reflectivity (transmittance);

Photoelectric sensors due to high sensitivity, light-emitting tube with time temperature and other factors, the light-emitting power will have a slight decline; for the receiving tube, if the continuous reception of reflected light, the performance of its parameter drift is very large, therefore, in the application of photoelectric sensors, in the design try to avoid aging this problem, such as:
① POS machine paper will be the end of the detection, usually paper, photoelectric sensor receiver tube is not received reflected light, paper will be the end of the paper, the paper tube fell into the paper bin groove, photoelectric sensor receiver tube only to detect the reflected light and thus alarm;
② the use of intermittent light-emitting method, when the detection of the sensor is connected to the power supply of the light-emitting diode, do not detect the light-emitting diode power supply is turned off, reducing the light-emitting diode and receiving tube aging;

Different sensors and detection media, the discrimination of the voltage threshold varies greatly, the selection of practical discrimination threshold, the correct detection of different media is of great significance, two-value detection: at this time the sensor should be made to work in the saturation area and up to the area, the voltage difference is large, the threshold is relatively easy to select, adjust the load resistance of the sensor, through a simple level recognition, you can correctly determine, such as the presence of paper detection, there are Intermediate state of detection: such as label paper need to detect the presence of paper, paperless and lined paper, at this time should make the sensor as far as possible to work in the linear zone, so that the different state changes, the most obvious changes in its output voltage, the most conducive to the different states of discrimination, so that the sensor can be based on the sensor in different states of photocurrent and reflectance (transmittance) changes, to select the appropriate threshold for detection;

The same type of sensor in the same input conditions, because of its own discrete caused by the output of the different, to the detection of the signal to bring about adverse effects, especially on the work in the amplification area of the sensor has a very serious impact, such as SG-23FI, the same in the VCE = 5V, IF = 10mA, the photocurrent range of 0.5mA ~ 3mA, a difference of 5 times, in order to adapt to the impact of sensor discretisation, the current situation is the same, the sensor is not the same as the sensor. The discrete nature of the impact of the current method used by our company:
① Add adjustable resistors to adjust the output voltage does not meet the requirements of the sensor, so that its output to meet the requirements, but to the production of increased difficulty and cost;
② use multiple CPU ports to switch different load resistors to adapt to different media, need to take up additional CPU resources, adjustable range is not large, can only change a few states;
③ Using PWM to adjust the current intensity of the light-emitting tube to make the sensor work in different output characteristic curves, with a large adjustable range, but increasing the difficulty of firmware detection.