How to mention a completely rewritten article in PhD thesis?
because I didnt want to give a Journal the copyright of a part of my PhD thesis


Have you checked the copyright agreement? Various academic publishers explicitly make an exception of their exclusive right of publication of the material (although graphics might be a different question) for the author's educational theses.


  Would you recommend to let the reader know that the ideas of this chapter have been published in a journal?


Yes, this is absolutely required. Otherwise, you are committing self-plagiarism, which is considered a form of academic fraud. This could have severe repercussions during your later career. The reason is that if no citation is given for something non-trivial and substantial, the reader will assume it is new and has not ever been published before it appeared in your thesis.

A good idea to handle this is to add a remark in the beginning of the respective chapter(s) that says that the following text is partially/largely based upon your journal article.