Keyence is one of the leading manufacturers of laser products in factory automation and first explored the digital micrometer market in 1986.
The only digital micrometers available at that time used lasers. However, laser micrometers used motors and motors had some disadvantages such as limited speed and short lifetimes.
The first step in developing an alternative was to determine what could be done to make them faster and extend their lifetimes.
"The LED held the potential to solve these problems" recalls a smiling Yuji Akishiba, LS-7000 project manager. The challenge of developing digital micrometers using LEDs started five years ago. But in contrast to his smile, the path to success was a series of difficult trials.
Keyence was the first to develop LED micrometers. Compared with conventional laser systems, LEDs are typically too dark to achieve high-speed performance. Using a megapixel CCD receiver for high accuracy results in a further reduction of the amount of light per pixel. A number of different methods were tried, resulting in failure after failure.
“The idea of calling off the project was raised more than once,” recalls Mr. Akishiba. Technical hurdles and a lack of early progress nearly derailed the project because it seemed too technically difficult and costly.
A glimmer of hope remained for a solution. Although the LED light had already reached the limit of its intensity, the Keyence team succeeded in developing an optical device that amplifies brightness.
To achieve the necessary high accuracy, a method using a low-resolution CCD and making up what was needed through electronic processing was studied. Generally, all CCDs made today are high resolution so the team came up with the idea of using a high-accuracy CCD at low resolution.
Dimensions can now be measured in microns at high speed. The key to achieving performance previously thought impossible was to change the light source from laser to LED. The simplicity of the optical system using an LED phototransmitter and HL-CCD photoreceptor means improved usability and less maintenance.
The newly developed intelligent optical measuring system integrates a phototransmitter that generates uniform light transmission and a photoreceptor that instantaneously detects positioning information, offering a high level of performance. This enhanced system provides best in class precision.
The new optical system and Digital Edge-detection processor provide twice the accuracy. It's suitable for the wide range of high-accuracy measurement applications required for high-precision products. This new design also enables high-accuracy measurements without optical-axis movement, a common problem with scanning systems.
High-speed and higher reliability are possible for in-line applications such as sequential measurement of extruded products and moving objects. The HL-CCD uses continuous exposure measurement, which continuously measures average values to provide constant detection. This enables even transient variations in diameters to be detected.
The target viewer displays real-time images of the measuring process for more accurate positioning of measurement points and verifying measurement conditions. Well received by customers for its ease of use, this is a first time feature for outer diameter micrometers.