Wavelength Conversion SheetBack light type inspections without the use of a back light.
CA-DWC30
Wavelength conversion mechanism
By combining the wavelength conversion sheet, blue LED lighting and a blue cut filter, a new lighting technique has been realized that can produce back light images using front lighting.
With only the ambient light
This is the image obtained when a white part is placed on top of both the wavelength conversion sheet and a white sheet.
Install a blue bar light.
This is the image obtained when the blue light is emitted. The white background and the white sheet are imaged in blue. The waveform conversion sheet converts the blue light to an orange color tinged with red and reflects this color.
In addition, install a blue cut filter on the lens.
The blue cut filter blocks the reflected light in the blue range, and only the light from the wavelength conversion sheet enters the lens. In this way, an image like that captured of the white part with a back light is obtained.
Application
Alignment
It’s difficult to route cables with embedding light in a moving stage, but there are times when the contrast with a reflected light is insufficient. By using the wavelength conversion sheet, it’s possible to realize back light images without any wiring, which makes stable detections possible.
Using only blue reflected light
The contrast for the alignment mark is insufficient, so stable detection is not possible.
Using the wavelength conversion sheet
The contrast obtained is equivalent to that of images captured with back lights, which improves the alignment precision.
Liquid surface inspection
Assume that there is no space to install a back light when performing liquid surface inspections at a filling machine, so a front light has to be used instead. Even if the light is installed in a narrow space, back light images can be realized by wrapping the wavelength conversion sheet around the rotating object.
Using only blue reflected light
Due to the effect of the reflection from the target surface, it is not possible to obtain a stable view of the liquid surface.
Using the wavelength conversion sheet
Only the liquid surface is clearly imaged as a back light image, which makes it possible to perform stable liquid surface inspections.
There may be foreign substances on the surface of the wavelength conversion sheet. However, even if such substances are present, the product is still within the inspection standards, and these substances do not indicate that the product is defective.
