What Is an Image Recognition Sensor?
An image recognition sensor is a device that utilizes images captured by a camera to determine the presence or difference of objects. It calculates characteristic quantities like shape, area, center of gravity, length, and position of the object, then compares these with preset data and criteria to output the results of its discrimination.
Uses of Image Recognition Sensors
These sensors are widely used in manufacturing sectors to automate and enhance inspection processes. In automobile manufacturing, they assist in producing and inspecting small parts like screws, detecting foreign objects before shipment, identifying flaws, and assessing the quality of plating.
Image recognition sensors are also crucial in the electronic component industry, where products are extremely detailed and challenging to inspect visually. In the pharmaceutical and food industries, these sensors often make judgments based mainly on color, as the objects do not have uniform shapes like industrial products.
Principle of Image Recognition Sensors
1. Image Signal Acquisition
The process begins with capturing light through a camera lens, which is then converted into an electrical signal by an image sensor, such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor). The number of dots in this array is known as the pixel count.
2. Pre-processing
Pre-processing involves transforming the electrical signals into an easily measurable image. This includes smoothing to reduce image irregularities, expansion, and contraction to remove noise, and edge extraction for flaw inspection.
3. Position Correction
Since the inspected object’s position and orientation relative to the lens can vary, position correction is performed to move the detected image to a more measurable location.
4. Feature Extraction
After position correction, the next step is to extract the necessary feature values from the image for inspection. For instance, large changes in brightness can indicate an item’s contour, while differences in brightness within small areas can reveal scratches or stains.
While image recognition sensors convert images into electrical signals, operators often set the pass/fail criteria. Recently, AI has increasingly been used for this judgment process.
Other Information on Image Recognition Sensors
What Image Recognition Sensors Can Do
1. Inspection for Foreign Matter Contamination
These sensors can check for foreign matter by comparing captured images with registered standard patterns.
2. Contour Detection
By setting specific conditions for search direction and color change, these sensors can detect differences in image density and brightness, identifying product abnormalities and contamination.
3. Character Verification Inspection
This function verifies the correctness of printed details, such as part engravings or labels and expiration date printings.