Use of mobile during hospital duty - some are playing game, some busy on Facebook - Should I circulate notice?

Hi, I have recently joined a hospital as HR. During daily rounds I have noticed that many employees use their mobile phones, some are playing game, some busy on Facebook. They always pretend that they were talking with co workers or some other excuses.
Can anyone guide me how to resolve it. Should I circulate notice? If any policy is there to assist me in this regard. Thanks

Hi, please guide me to resolve this problem and suggest me the measures. If some has any circular or notice then please share it.

I am happy that you are so proactive.
But remember that we people are so addicted to use of mobiles, that any restriction will be viewed with unhappiness and anger.
Having recently joined an institution, study the environment and working pattern, culture etc.
Bring it up in discussions with HODs and get their views.
If there is general agreement then let the higher ups take the call of banning or restricting mobiles.
Technology has caused life and work to blend and one therefore needs a mobile usage policy.Frame one after taking inputs from HODs and then let senior management take a call.
Really in a hospital you cannot ban mobiles,the staff may be urgently calling a doctor or asking for medicines etc.So be judicious and keep higher ups in the loop.After all they also must be seeing the usage of mobiles by staff during duty hours.

I really appreciate the suggestions you provided to me. I will ask the HODs concerned and definitely frame a policy. I admit staff may call doctor, pharmacist may contact vendors for urgent medicines etc. But on duty playing game, watching movies on youtubes, chatting with others on WhatsApp, using Facebook which I think is a misconduct and in my opinion it's a misbehavior also which should not be acceptable.
Thank you very much Mr. Rao for sharing valuable points which I will keep in mind.

A theoretical or dogmatic stand is not desirable. In my understanding, HR has their limitations in monitoring the functions at the micro-level. However, the matter needs to be brought to the notice of the HODs and a practical/viable policy is intimated.