Horological movement comprising a chronograph mechanism

A horological movement comprising:

• a running train dedicated to the time division of said horological movement, said running train being driven by a first energy source;
• a regulating member for regulating the running train;
• a chronograph mechanism comprising a chronograph train driven by a second energy source;
• a coupling configured to couple the chronograph train, on demand, to the regulating member to regulate the chronograph train using the regulating member;
• a chronograph start/stop control device cooperating with the coupling;
• characterised in that wherein the coupling is a differential coupling comprising:
• a first input wheel driven by said running train and having a rotational speed that is regulated by the regulating member;
• an output wheel meshed with said chronograph train;
• a second input wheel, which is an idle wheel, cooperating directly or indirectly with the chronograph start/stop control device;
• the coupling comprising a drive assembly configured to rotate the output wheel at said rotational speed regulated by the regulating member, when the rotation of the second input wheel is blocked by the chronograph start/stop control device.