A spectroscopic camera

A spectroscopic camera for distinguishing subtly different colors

Appearance inspections are sometimes necessary on manufacturing lines to ensure color consistency and product quality or to check surface coatings, for example. These inspections were most often performed visually, relying on human sight to distinguish subtle color differences. Epson, with its printers and projectors, is in the color business, so it's not surprising that we have successfully automated appearance inspections that formerly relied on human eyesight by using a compact, lightweight spectroscopic camera.

Issues with appearance inspections that rely on human eyesight

Appearance inspection issues

Appearance inspections are used to check for subtle differences in color, check surface coatings, and verify that the color of a product meets passing criteria. RGB cameras are frequently used in appearance inspections to analyze images, but currently popular RGB cameras cannot capture detailed color information and are not always able to distinguish subtle differences in color. Conventional spectroscopic cameras are large and expensive, so manufacturers were reluctant to install them in their manufacturing lines due to space and cost considerations. Line sensor systems that have multiple small optical sensors can also be used, but images must be synthesized after they are scanned, making it difficult to complete inspections in a short time. Automated color management can be difficult and costly, so, even today, appearance inspections are usually performed visually by humans.
However, visual inspections that rely on human eyesight can be risky, as defective products could make it to market as a result of individual variances among inspectors and human error. The training of inspectors also takes time. Automating appearance inspections was a significant issue in manufacturing line automation.

Value provided by spectroscopic cameras in inspection processes

Characteristics of Epson's spectroscopic camera

Epson's spectroscopic camera was developed to solve issues in inspection processes and to provide three types of value:

Spectroscopic camera

Quantification of inspections through automation

Quantifying visual inspections that are performed by humans is difficult due to variations among individual inspectors and human error. Epson's spectroscopic camera makes it possible to perform inspections with the same criteria on any manufacturing line. They quantify inspections and stabilize production quality.

Integration into manufacturing lines

Conventional spectroscopic cameras were large, so integrating them in manufacturing lines as replacements for RGB cameras was difficult. Epson's spectroscopic camera, however, is about the same size as an RGB camera, facilitating swap-outs. We provide a dedicated controller and software system along with our cameras so that they can easily be installed in existing manufacturing lines.

Output images without the time and trouble of image synthesis

Appearance inspections performed using line sensors slow down production on the entire manufacturing line because of the time it takes to synthesize images. Epson's spectroscopic camera can quickly and easily output images because there is no need to synthesize the images after they are captured.

How spectroscopic cameras work

RGB camera
Spectroscopic camera

Spectroscopic camera mechanisms

Epson's spectroscopic camera uses a unique spectroscopic device to resolve light from an inspected object into multiple wavelengths and obtain spectroscopic images of each wavelength. If there are scratches or deposits on the surface of a product, or if a surface coating is not properly distributed, the light scatters in the area where there is an irregularity, so the amount of light obtained in the image changes. The condition of the surface of a product can be checked by reading the scattering of light from any of the spectroscopy images. In addition, multiple spectroscopy images can be combined to precisely determine the color of a product. It is thus possible to inspect both the condition and color of the product surface with the capture of a single image, thereby reducing the number of steps in the production line and reducing costs.

Eliminating variation in visual inspections using a spectroscopic camera

Eliminating variation in visual inspections

Epson's spectroscopic camera automates visual inspections and improves product quality by reliably identifying defective products before they are released and eliminating variations.

In recent years, there has been an increase in the diversification of personal tastes as well as an increase in demand for customized products, including products with custom colors. This is making the accurate inspection of colors even more important. Epson's spectroscopic cameras will achieve both high quality and improved productivity in the inspection process for products such as cosmetics, foods, toys, stationery where colors that were previously difficult to automate are valued.