I want to ask how to search for patents of the same family. JP 1 1504028 cannot find this patent.

The reasons for not retrieving related patents may be:

1. The invention-creation is in the state of undisclosed (referring to the invention patent application), undisclosed (referring to the utility model or appearance patent application) and confidential patent application.

2. The entered search criteria are too strict. Please use broader search criteria and search again.

3. The search criteria were entered incorrectly.