Feature

Ultrasonic sensor

Photoelectric sensor

Working medium

Sound (ultrasonic, typically frequency>20kHz)

Light (visible light, infrared light, laser)

Basic Principles

1. The sensor emits ultrasonic pulses.

2. The pulse reflects back after encountering an object.

3. The sensor receives the echo and calculates the round-trip time of the sound wave.

4. Calculate the distance to the object based on the speed of sound. (Distance measurement principle)

1. The transmitter emits a modulated beam of light.

2. The receiver detects changes in the light beam.

3. Determine the presence or absence of an object based on whether the beam is obstructed or reflected by the object. (Principle of on-off)

Feature

Ultrasonic sensor

Photoelectric sensor

advantage

1. Not affected by color or transparency: It can detect any object that can reflect sound waves, whether the color is black or white, transparent (such as glass, liquid) or opaque.

2. Anti environmental light interference: It is not affected by changes in environmental light, and works the same day and night.

3. Distance measurement: It can directly output distance values and achieve non-contact distance measurement. 4. Large detection angle: The detection area is relatively wide.

1. High precision and fast response: The speed of light is extremely fast, so the response time is very short, suitable for high-speed detection.

2. High resolution: The light spot can be made very small and can detect very small objects.

3. Wide variety: There are multiple detection modes (reflective, diffuse reflective) to adapt to different scenarios.

4. Low cost: Ordinary photoelectric sensors are usually cheaper in price.

shortcoming

1. Influenced by environment and material: Soft, porous objects such as fluff and cotton can absorb sound waves, making detection difficult. Extreme temperatures and airflow can also affect sound velocity and propagation.

2. There is a blind spot: it cannot be effectively detected within a certain distance close to the sensor (blind spot).

3. Slow response speed: The speed of sound is much lower than the speed of light, so the response time is relatively long and not suitable for high-speed applications. 4. Surface measurement requirements: The surface needs to be flat and conducive to sound wave reflection.

1. Influenced by object characteristics: Objects that are transparent, highly reflective, or have a similar background color can cause detection failure.

2. Interference from ambient light: Strong light sources (such as direct sunlight) may interfere with the sensor, leading to misoperation.

3. Unable to directly measure distance: Ordinary photoelectric switches can only determine "presence/absence", and special models (such as laser ranging sensors) need to be selected for distance measurement.

4. Sensitive to dust and mist: Particles in the medium can scatter light, affecting detection distance and reliability.

Feature

Ultrasonic sensor

Photoelectric sensor

Typical applications

1. Liquid/material level detection: such as water tanks, grain silos, and chemical raw material tanks.

2. Transparent object detection: bottled beverages, glass plates, plastic films.

3. Vehicle reversing radar/parking assist

4. Robot obstacle avoidance.

5. Distance measurement: such as measuring the height and width of an object.

1. Object counting: Counting the packaging of products on the production line.

2. Positioning and end of travel detection: such as the starting/ending position of the robotic arm.

3. Color code detection: Using different color reflectivity to locate (color code sensor).

4. Safety light curtain: protects the safety of operators.

5. Automatic door sensing.