Patent ID: 8770694

Claim:
A printing element substrate comprising: a printing element; a switching element which drives said printing element based on an input control signal; a first current source which generates a predetermined current; a second current source which generates a current based on an input voltage; a current generation circuit which generates the control signal by amplifying a current obtained by adding a current generated by said second current source to a current generated by said first current source, and then generates the control signal by amplifying a current generated by said first current source; a first signal line which supplies a current from said printing element to said switching element; a second signal line which supplies a reference voltage; a third signal line which supplies the voltage of said first signal line to said second current source; and a first switch which is inserted in said third signal line and switches said third signal line between connection and disconnection based on a driving signal for designating driving of said printing element, wherein said first switch is controlled to a connected state when the driving signal for designating driving of said printing element is active and a disconnected state when the driving signal for designating driving of said printing element is inactive.