According to the judicial interpretation of the Supreme Court, an application for suspension of trial must be submitted within the defense period and be accepted. However, if the reasons for invalidation are sufficiently evidenced, even if the invalidation request is submitted after the defense period, The court may also consider a stay of proceedings. So this is not certain. The patent infringement lawsuits I have done before in Shanghai and Hangzhou were not requests for invalidation during the defense period, but the evidence of invalidity was sufficient, so they have been suspended now. It is best to submit a written application to suspend the trial.