In many German companies, the employee invention act is unfortunately very shabbily treated. This falls, however, under some regulations which put the employed inventor in a comparatively strong position, especially in respect of the so-called claiming of the invention. Resulting thereof are not to be underestimated traps for the company which can have subsequently serious consequences.
Here is my advice: have a concept worked out to deal with inventions of your employees which you universally apply in your business.
Look at the inventor’s remuneration not from a cost point of view, but as a chance to motivate your employees to creative thinking. This will pay out in the long run.