In the ideation phase, multiple voting periods can be set up where each player is allowed to give a limited number of votes, for example. After a voting period, the vote can no longer be changed. Within a voting period there is an option that a player may withdraw his vote.
This method ensures healthy competition of ideas and is particularly transparent.
As an innovator (owner of an idea) you also have insight into who voted your idea. These are your sponsors. So voting is not anonymous.