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16 Aug, 2022

Proximity Sensors and Their Usage in Access Control Systems

Access control can be exercised with the help of several kinds of components like card readers, biometric scanners, proximity sensors, etc. You should choose the appropriate access control system depending upon the requirements of your premises. One of the popular choices for access control in commercial buildings is proximity sensors. With this blog, we shall learn in detail about what is a proximity sensor and how it helps organizations establish effective security.

To learn about access control systems, click here.

What Is a Proximity Sensor?

A proximity sensor is a sensor that is designed to detect the presence of an object near it without initiating actual physical contact. There are many proximity sensor types that have different working principles.

Proximity sensors are an advantageous component for any access control system as they involve the user’s minimal action to activate the protection provided by the security system. When near the access control device, the proximity sensor detects the user and grants permissions accordingly. When away, the proximity sensor arms the access control system again to prevent unauthorized usage.

Proximity Sensor Types

  • Capacitive
  • Capacitive displacement sensor
  • Doppler effect (sensor based on doppler effect)
  • Inductive
  • Magnetic, including magnetic proximity fuse
  • Optical
    • Photoelectric
    • Photocell (reflective)
    • Laser rangefinder
    • Passive (such as charge-coupled devices)
    • Passive thermal infrared
  • Radar
  • Reflection of ionizing radiation
  • Sonar (typically active or passive)
  • Ultrasonic sensor
  • Fiber optics sensor
  • Hall effect sensor

Proximity sensors produce a high-speed response, that is, the duration between the time when an object triggers the proximity sensor and the time when the programmed output is received. Different proximity sensor types use different sensing technologies, but they all serve the same end goal.


How does a proximity detector work?

As mentioned above, when something or someone comes near the read-range of a proximity sensor, it gets triggered and produces an electric signal. This signal is called the “output” that communicates the information which the sensor is programmed to deliver.

Depending on the type of proximity sensor, sound, light, infrared radiation (IR), or electromagnetic fields may be utilized by the sensor to detect the target.

Working Principle of a Capacitive Proximity Sensor

Capacitive proximity sensors detect changes in the electric charge between the sensor and an object. Many determining factors such as distance and the size of the object will affect the amount of electric charge that is registered by the sensor. In simple terms, a capacitive proximity sensor just picks up any changes in capacity generated between the sensor and the object.

Working Principle of an Inductive Proximity Sensor

Inductive sensors detect eddy currents causing magnetic loss, generated by external magnetic fields on a conductive surface. The detection coil in the sensor produces an AC magnetic field, and impedance changes are detected as a result of generated eddy currents.

Eddy current: A localized electric current induced in a conductor by a varying magnetic field.

Impedance changes: The effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance.

Working Principle of a Magnetic Proximity Switch

Magnetic proximity switches are comparatively simple and straightforward. The electrical end of the switch is operated by a magnet. When the electric switch is activated and ON, the sensor also turns ON.

Another important feature of proximity sensors is that they are not affected by the surface color of the object detected. They only catch the physical movement and the motion of an object, so the color of the material has no role to play in proximity sensor uses or effectiveness.

Can proximity sensors detect humans?

Yes. Capacitive proximity sensors can detect humans at a short range. Passive infrared (PIR) sensors can also detect human bodies but only if they are in motion. Ultrasonic sensors have been known to have a better detection range than PIR sensors to detect human presence.

How far can a proximity sensor work?

As mentioned earlier, different proximity sensor types work according to different principles. Therefore, each sensor has its own range of detecting objects. The following table can help you understand the read-range of a few of the common sensors being used today:

proximity sensor types and max range


Proximity Sensor Uses

Different sensors have different applications, so, it is important to understand and choose the right proximity sensor for your purpose. Leaving aside all the technical concepts and discussions, proximity sensors are significantly used for granting and restricting access.

Proximity sensors do not require physical contact which is why they are useful for areas where there’s a lot of dirt and dust, and where access with physical contact proves to be challenging. Examples of this can be construction sites or research labs where employees have their hands covered with gloves almost all the time.

Most of the smart doors in office buildings are designed to function with proximity sensors, enhancing the capabilities of a commercial door access control system. Such automatic door lock systems ensure that your office’s doors are secure even after-hours.

Proximity Sensors & Access Control

More and more design engineers are selecting proximity sensors for their versatility, reliability, durability, and cost-efficiency over mechanical switches for access control. Automatic door units such as garage doors, or doors inside buildings, elevator doors, etc. all work more efficiently with proximity access control.

Motion sensors are being extensively used in commercial applications. The most common form is activating automatic door openers in businesses and public buildings. In offices with hundreds of employees, the risk of infections spreading is quite huge. Proximity access control can help avert such mishaps. Proximity sensors make access control systems highly scalable.

What is the benefit of a proximity sensor?

Proximity sensors are highly durable – they have a long functional life. This factor makes them highly reliable and cost-effective. Since proximity sensors don’t come into contact with objects and people, they are less likely to be exposed to wear and tear of any kind. Also, in terms of power usage, proximity sensors are a good choice, especially capacitive sensor.

With increased automation of complex production systems, proximity sensors effectively fulfill the requirements of acquiring and transmitting information regarding the production process in the form of individual process variables to controllers.

Proximity sensors are smaller in size and incur a lesser cost to be made. For these reasons, they are more popularly utilized for various purposes ranging from the manufacturing sector to simple mobile-phone usage. Because of high operating frequency and high sensitivity, you can get quick and accurate outputs, enabling further decisions.

How Does Spectra Utilize Proximity Sensors?

Spectra understands the significance and utility of proximity sensors which is why it has a range of devices supporting this technology. Its latest offering, XsPoint Plus, is a highly reliable, extremely secure contactless card reader for access control applications.

XsPoint Plus

Each of Spectra’s devices is created to enable smooth data communication across channels. Extending an elegant look and feel, Spectra emphasizes durability and reliability which is why it employs IP65 standards of protection for its products.

No matter the industry you are working in, proximity sensors are utilized almost everywhere, and they ease the processes of detection, inspection, production, and environment control.

The Final Rundown

In a nutshell, there are quite a few reasons why businesses and manufacturers are opting to go with proximity sensor-based access control solutions. Touchless entry for commercial doors can facilitate getting into the premises in a more convenient and secure manner, as well as prove to be a lucrative return on investment.

To know more about Spectra’s range of devices that install proximity sensors, click here.

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