Larger Sizes and Faster Readout
C-mount lens compatible image sensors are a standard option for machine vision cameras, but it is expected that further productivity improvements will be achieved by using image sensors with larger image sizes to expand the imaging area. For example, if the images taken with the IMX253 (12.37MP, 17.6mm diagonal length) image sensor are compared with those of the large diameter IMX661 (127.68MP, 56.7mm diagonal length) image sensor, the latter enables to lower capture frequency. It also enhances recognition accuracy by the high resolution imaging. In inspections of flat panel displays, moire occurs when the resolution of the image sensor is insufficient for the resolution of the panel, so it is highly effective to perform oversampling inspections using an ultra-high resolution image sensor. In addition, with the IMX661, the use of the SLVS-EC (Scalable Low Voltage Signaling with Embedded clock) high-speed interface standard realizes a high-speed image readout that is four times faster than on the conventional models.
SWIR Image Sensor
The IMX990/IMX991 image sensors released in 2020 made it possible to use a single image sensor to take images over a wide range of wavelengths including visible light, from 0.4 to 1.7m. In the development of the SWIR sensors, the use of a Cu-Cu connection realized a smaller pixel pitch and wideband imaging, creating a new type of image sensor supporting SWIR. The SWIR wavelength region makes it possible to see indentations under the surface layer on fruit (by making the differences in moisture density visible), and to detect plastic or metal fragments included in food by using the light absorption and reflection characteristics in the SWIR range. The technology is also used in inspections that utilize the properties of light in the SWIR range, such as in inspections that utilize the characteristic of SWIR band light that it passes through silicon materials. It is a device that increases the possibilities in inspections, such as because inspections that previously used multiple cameras for imaging in visible light and in SWIR can now be performed with just one camera and to increase throughput with higher image processing speeds.
Optimized for Edge Systems
When image data is processed by AI or machines, an effective method to shorten the inspection time and improve the data processing efficiency is to cut out just the areas necessary, to narrow down the information and reduce the processing time. Our image sensors are equipped with an ROI function to identify just the areas necessary, and a self-trigger function to output just the data from the instant necessary. The stacked structure has also enabled the inclusion of two AD converters and the sensors are equipped with a function to internally combine data with different gain. The HDR processing that is normally achieved by overlaying multiple images can be processed without the occurrence of artifacts. In addition, completing the combination inside the sensor means that the volume of data output remains the same as on the conventional models, realizing a highly robust sensor. This kind of functional expansion is realized by stacking technology. As shown in Image 5, the key point for stacking technology is that the wafer processing for the pixel section can be separate from that for the circuit section, so it is possible to have image quality improvement and function expansion scalability.