question/problem concerning GRANT/REVOKE

hi!

I have a pretty basic problem: We have several schemas in one of our
databases, and we need the users to see only the tables (and table
structure) of tables inside their own schema.  So I created schemas for
those users, and set their "search_path".

But with \d public.<tab key> users can see all tables (and their
structure) in the public (and other) schemas -- and I found no way yet
to prevent this??

I have tried "REVOKE ALL" from the database itself, and the other
schemas, and single tables -- for the specific user, and also for the
user "PUBLIC" -- but it had no effect!
How can I prevent exposing the structure of all tables in the database
to user that should work in their SCHEMA?

Help would be appreciated very much!! :-)

cheers,
gerhard