Web Inspection with BergKristall Sensor Chip: Applications & Insights

Tichawa Vision GmbH Bergkristall Contact Image Sensor Scanner ( (image courtesy of Tichawa Vision)

Andrea Fant (ISDI) and Nikolaus Tichawa (Tichawa Vision GmbH) presented on ‘Inside View of BergKristall Sensor and web inspection solutions with Contact Image Sensors’

At VISION on Thursday 10th October 2024 at 02:20 PM - 02:40 PM in Industrial VISION Days, Alfred Kärcher Halle (Halle 8), 8C70.

Vision 2024 (8-10 October in Stuttgart)

The BergKristall sensor chip sets a new benchmark in the field of Contact Image Sensors (CIS), outperforming any other CIS sensor chip currently on the market in terms of speed, resolution, and flexibility. It features unparalleled specifications with a speed of 1 MHz (5 times faster), a resolution of 4800 dpi (4 times higher), and flexible resolution options of 8, 10, or 12-bit, complemented by gain adjustment.

BergKristall Contact Image Sensor designed by ISDI ( (image courtesy of Tichawa Vision)

Engineered to meet ambitious performance targets for challenging scanning applications, including paper printing, semiconductor manufacturing, and flatness defect detection, the BergKristall sensor employs a dual-resolution array with unique two-sized 4T pixel design, featuring 21.16µm and 5.29µm elements. This design achieves dual resolutions of 1200 dpi and 4800 dpi, respectively, to cater to various application needs.

BergKristall's innovative structure combined with advanced FPGA technology maximizes sensor performance. The CIS is gapless even at large scan widths and features a flexible light source multiplexing scheme that, along with near-zero image lag, significantly enhances colour measurement across 3 to 8 colours. Its 12-bit grayscale resolution and more enable powerful density measurements in the printing industry. A raw line rate of 1 MHz supports 400 m/min in RGB and 300 m/min with Shape from Shading versions.

Dynamic pixel positioning ensures that red, green, and blue pixels are in exactly the same location, a significant improvement over Bayer pattern or 3-line sensors. Additionally, flexible 1D or 2D ROI features reduce video bandwidth to necessary levels. The high-performance Shape-from-Shading version outperforms other solutions with its compact size (130 x 100 mm cross section) and ultra-high speed (300 m/min web speed), enhanced by a new optical design that eliminates stray light. Banding correction ensures image stability in critical applications such as high-speed wafer scanning.

The sensor’s analogue front end incorporates a ramp ADC capable of correlated double sampling (CDS). This ADC uses a central ramp generator for scanning dark and light levels, ensuring differential code readout. On-chip digital control logic supports random row addressing and partitioned column sections, facilitating the implementation of 2D Regions of Interest (ROI) and optimizing data output through multiplexing up to 8:1, based on required application frame rates.

The digital outputs are transmitted via 8x LVDS outputs, each operating at up to 1 Gbps using a clock-forward interface. The final die size is 21x4.72mm², designed for overlap at both short ends and staggering along the long direction.

The BergKristall-based Contact Image Sensor is an exceptional solution for demanding print inspection, wafer inspection, and general web inspection applications, offering a combination of unmatched resolution, speed, and advanced technological features.

To find out more about ISDI’s custom design services click here.