1 patent sub-invention utility model appearance In general, you should first search whether there are the same and similar prior patents, in case your application is not passed.
Secondly, if you want to write a good copy, you will succeed more than half, because most of the auditors in the patent office are not your professionals. As far as technology is concerned, you must be the most professional, but you must write your technical scheme for the other party to understand and agree with. This is a kung fu, and you shouldn't write too rigorously. This not only can't protect their own technical core from being leaked and used by others, but also the scope of protection is too detailed and others can reapply with a little modification.