Reflection sensors

The reflection sensor is a device that can be found in thousands of robotic projects, especially the more advanced ones. Line followers are a good example. The task of such a robot is to follow a path in accordance with the course of a line drawn on the surface. Typically, line followers fall into two categories: devices that follow a white line on a black background in reverse, i.e. devices that follow a black line on a white background. In order for the robot to be able to properly follow its path, it must be equipped with appropriate equipment. Such a device - apart from power supply and drive, microcontrollers and a processor - is the reflection sensor. Reflective sensors effectively warn of potential obstacles on the track. See all products available in this category. Choose the highest quality sensors that meet your needs now.

The principle of operation of reflection sensors

Reflective sensors can be used both for Internet of Things projects and for building your own robots. There are many types of these devices. How do reflection sensors work?

In general, it can be said that reflection sensors are such elements of industrial automation that work by interrupting the light beam sent from the sensor. This light beam is reflected back from the reflector. So the reflection sensors use visible and invisible light (most often infrared but also ultraviolet), ordinary and laser. One of the simplest variants is an optical reflective sensor that uses an infrared LED. Additionally, they are paired with phototransistors. The phototransistor is connected to the supply voltage source through a resistor forming a voltage divider. It is worth to mention that at the output of this divider a voltage of 0V to typically 5V is obtained as a representation of the IR reflection, with the lower value representing a stronger IR reflection.

In terms of electrical voltage issues, the way the sensors work is easy to understand. The analogue output of the sensor, while supplying the received voltage, can be connected for further reading in various ways. How to do it? The simplest technique is to connect the sensor output to the analog input of the ADC on the microcontroller or to the binary input using a software comparator. The second option is to connect the sensor to a hardware comparator with an adjustable logic change threshold (LM393 integrated circuit). A two-state microcontroller is required for reading. While new reflection sensors now work through infrared and LEDs, there was once an incandescent or discharge (UV) light source.

Types of reflection sensors

There are plenty of reflection sensors that might be used in various projects. Some devices are used to build robots and DIY Internet of Things projects, while others are used in industrial automation (production lines).

Reflective sensors is a name that covers a whole group of different devices. They work similarly, but you can see differences based on how the returned light is used. In this respect, we can distinguish between classic distance sensors, color sensors, contrast sensors and surface smoothness sensors (also known as gloss sensors; gloss meters).

The sensors shown here can be implemented in different places. Due to the small dimensions of the sensors, they can be easily connected in parallel in the form of a bar, which allows easy detection of edges, walls and other obstacles, including the possibility of measuring the distance from them.

Measurement accuracy of reflection sensors

Laser and optoelectronic sensors have very good measurement accuracy and are well suited for many hobby and advanced projects. To get the best possible sensor accuracy, perform a calibration first. Calibrating a proximity sensor is an important process as there are no ideal sensors and, despite the repeatable production technology, two identical sensors can output different voltage values. The method of calibration also affects the accuracy of the measurement. In many cases, it is worth choosing programming. These steps will be very simple if you are also using Arduino. The presented sensors are compatible with various programmable electronics components.

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