Coin Sorting Device Using Oblique Optical Imaging
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Solution Overview
Problem
Existing coin sorting devices are too large for vending or gaming machines due to the positioning of the coin reading unit, and conventional solutions either increase size or compromise on determination accuracy when using CCD cameras for image pickup.
Innovation Solution
A compact coin sorting device with a two-dimensional image pickup system that includes a floodlight projector, half mirror, lens, and image pickup element, where the floodlight projector uses a planar floodlight projector with a light guide and LED, and a reflective and diffusion sheet to project light uniformly onto the coin passage, allowing for authenticity determination based on image, material, and thickness information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the coin reading unit is positioned on the extension perpendicular to the coin surface to capture the entire coin image, then the measurement precision is improved, but the device size increases
Solution Approach 1:
The patent changes the optical arrangement from a perpendicular view (first conventional technique) to an oblique view from the side. The reading unit is positioned at an angle rather than directly perpendicular to the coin surface, allowing the entire coin image to be captured within a compact distance, thus resolving the contradiction between image quality and device size.
Solution Approach 2:
The patent employs a half mirror at a specific angle to redirect light paths. By using the reflective property of the half mirror, the optical system can capture the entire coin image while maintaining a compact device structure, effectively solving the size constraint without sacrificing measurement precision.
2Device complexity
If a line sensor is used in the reading unit to reduce device size, then the device complexity is reduced, but the measurement precision deteriorates because the picked-up line image is recognized as a plane
Solution Approach 1:
The patent uses a CCD reading unit that captures a two-dimensional image of the coin surface, creating a complete visual copy of the coin. This allows the system to maintain high measurement precision by analyzing the full image data, while the oblique positioning and half mirror arrangement keep the device size manageable.
Solution Approach 2:
Instead of using a line sensor that captures only one-dimensional data, the patent employs a CCD sensor to capture two-dimensional image data from an oblique angle. This dimensional change allows the system to maintain image recognition accuracy while avoiding the need for complex positive conveyance mechanisms.
3Volume of stationary object
If a CCD camera is used to pick up the linear image of the medal to downsize the device, then the device size is reduced, but the measurement precision deteriorates because the continuously picked-up partial images cannot be combined into the plane image
Solution Approach 1:
The patent positions the CCD camera to capture the entire coin image from an oblique angle rather than taking multiple partial images. This single-shot approach captures complete two-dimensional image data, allowing accurate authenticity determination without requiring complex image stitching or combination processes.
Solution Approach 2:
The patent uses a half mirror to pre-position and redirect the light path so that the entire coin image is captured in a single frame by the CCD camera. This preliminary optical arrangement ensures that complete image data is available immediately, eliminating the need for subsequent image combination or processing.
4Measurement precision
If the reading unit is positioned far away from the coin path to capture the entire coin image, then the measurement precision is improved, but the device size increases
Solution Approach 1:
The patent changes the viewing angle from perpendicular to oblique, allowing the reading unit to capture the entire coin image from a closer distance. This angular change in the optical arrangement enables high measurement precision while maintaining a compact device structure with reduced length.
Solution Approach 2:
The patent employs a half mirror at a specific oblique angle to redirect light from the coin surface to the reading unit. This angular arrangement allows the reading unit to be positioned closer to the coin path while still capturing the complete image, thus reducing the device length without sacrificing measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces the size of the device while maintaining accurate authenticity determination, enabling its use in vending and gaming machines without increasing size or power consumption.
Implementation Method 1
the planar floodlight projector which comprises a light guide positioned parallel to the coin passage and a LED being positioned to face a side end face of the light guide
Implementation Method 2
a LED being positioned to face a side end face of the light guide
Implementation Method 3
a half mirror, a lens and an image pickup element; the half mirror being positioned beside the coin passage
Implementation Method 4
a half mirror, a lens and an image pickup element
Implementation Method 5
a two-dimensional image pickup device... picks up a two-dimensional image of the rolling coin
Data Source
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Figure 3
AI summary
A coin which has been put into a coin slot (104) rolls along a coin passage (106). Light projected by a planar floodlight projector (132) positioned in parallel to the coin passage (106) transmits through a half mirror (134) toward the coin passage. A reflected light from the coin rolling along the coin passage is reflected by the half mirror (134), is guided in parallel to the coin passage (106), and reaches an image pickup element (138) via a converging lens (136). The image information picked up by the image pickup element (138) is compared with the reference information to determine the authenticity of the coin which has been put in. If the coin is determined to be a fake coin, a gate is not opened, and the coin is returned. If the coin is determined to be a true coin, the gate is opened, and the coin is accepted as a true coin.