I. Testing Background

As food-contact containers, the cleanliness of paper cups’ inner walls directly impacts food safety and brand image. During the paper cup production process, impurities such as paper debris, ink spots, dust, or foreign objects may appear on the inner walls due to processes involving raw materials, die-cutting, and molding. Traditional manual visual inspection is inefficient and prone to operator fatigue, while standard vision inspection systems struggle to fully cover the inner walls of deep cavities in a single pass. By employing a 360° inner-wall inspection lens, comprehensive impurity detection of the paper cup’s inner walls can be achieved efficiently and reliably.

II. Testing Requirements

1. Paper cup specifications: Standard size, rim diameter 75 mm, cup depth 90 mm

2. Inspection scope: Various impurities (paper fibers, stains, foreign objects, etc.) within a 360° range on the inner wall

3. Inspection accuracy: Must clearly capture images of minute impurities, with no blind spots or distortion

III. Testing Plan

A 360° internal wall inspection lens is selected and combined with an industrial camera and lighting to form an integrated inspection module. The key parameters of the lens are as follows:

• Maximum measurement height: 120 mm

• Maximum measurement diameter: 120 mm

• Working distance adjustment range: 2.7 mm to 70 mm

The 360° inner wall inspection lens employs a conical reflection optical design that projects a panoramic view of the paper cup’s inner wall onto a two-dimensional image, capturing the entire inner surface in a single scan. The working distance can be flexibly adjusted within a range of 2.7 to 70 mm to accommodate paper cups of different materials, colors, or reflectivity.

IV. Advantages of the Proposal

1. Full-field coverage, single-shot imaging: With a maximum measurement height of 120 mm and a diameter of 120 mm, the lens fully covers standard paper cup dimensions (rim diameter 75 mm, depth 90 mm). It captures a 360° image of the entire inner wall in a single shot, eliminating the need to rotate the cup or use multiple stations for imaging, thereby ensuring high inspection efficiency.

2. Adjustable working distance, high adaptability: The working distance adjustment range is 2.7–70 mm, allowing flexible focal length adjustment based on paper cup material, inner wall reflectivity, and impurity types. This ensures clear, low-distortion images of the inner walls for paper cups of different batches, colors, or coatings.

3. Wide installation tolerance and easy setup: The broad adjustment range compensates for positioning deviations or slight deformation of the cup rim, reducing requirements for mechanical positioning accuracy and simplifying on-site deployment and daily maintenance.

4. Precise foreign object detection: 360° blind-spot-free imaging combined with an adjustable working distance clearly captures minute foreign objects (such as paper scraps, ink spots, and dust) on the inner wall of paper cups, preventing missed detections caused by angular obstruction or poor focus.

5. Compatibility with Multiple Cup Sizes: The system’s maximum measurement capacity exceeds standard paper cup dimensions, allowing direct inspection of other irregularly shaped cups (such as bubble tea cups and coffee cups) with rim diameters ≤120 mm and heights ≤120 mm, ensuring high equipment utilization.

6. Compact design, easy to integrate: The compact lens, when paired with a standard industrial camera, forms a complete inspection module that can be easily embedded into paper cup production lines (such as at the exit of forming machines or pre-packaging stations), resulting in low retrofitting costs.