How can I require the pattern unlock only for specified times Is it possible to require the pattern unlock only during certain times? For example, while I'm at work, I don't want to require the pattern unlock, however, anytime I'm not at work I do.

Is this possible?
Sure. If you use automation app like Tasker, you can make your phone to disable screen guard, if it detects you are in your office. Detecting your location can be achieved in many ways. You could use any WiFi, if it can be used as a reference or rely on cell id, defining a radius. 

Please see a guide aptly named as Location without tears. It explains the various ways with which the Tasker can identify your location. It goes more explaining the pros and cons, the trade off between the battery life and accuracy etc.

I use Tasker in my mobile to reduce all volumes when I am in the vicinity of my office. I did this by creating a profile and choosing the State as my first context.



In the next screen Select Phone Action I selected Phone and select Cell near option. This brought up the following screen:



When I pressed scan Tasker started to log near by cell tower's id. I left it for a while and walked around my office so that it will gather maximum ids. I initially thought Tasker only retains last eight ids, but when I exported the profile to XML, I could see many entries. Hence the more time you keep it scanning and more walk around you make, more will be probability of successfully recognising your location.

Well that's only half job done. I then assigned an action that the Tasker can perform when this profile is active.  There are two kind of tasks - one is called entry task and other is called exit task.  I used Keyguard action to switch key guard off  as entry task, which will fire when this profile is made active. I used the same Keyguard action to swtich the key guard on as exit task so that when this profile is deactivated.