The idea of automatically limiting the amount of time kids can play video games is already one of the key features of Microsoft's Xbox 360 Family Settings. But is the approach worthy of a patent?

Microsoft apparently thinks so. In a patent application made public today, the company describes its approach for "Time-Based Access Control For An Entertainment Console," including the use of security codes and internal timers for parents to set the amount of time their children can spend playing the console each day or week.

"While entertainment consoles may already possess certain family control settings, such consoles typically do not provide an integrated mechanism for parents to limit how much time their children can use the console," says the filing. "When such a control setting is built directly into an entertainment system's operating system, the control features may fully take advantage of the hardware and software capabilities of the system."

Microsoft calls this feature the "Family Timer" in the Xbox 360. The patent filing was made in October 2007, weeks before the feature was introduced. Nintendo and Sony also offer parental controls in the Wii and PlayStation 3, but time limits don't appear to be among the options. But patent watcher theodp, who alerted us to the filing, points out another important precedent.

"Adult bookstores," he writes, "implemented 'time based access to entertainment consoles' four decades ago."