capacity c 105 of the inverter 105 in the first embodiment described above accordingly setting the capacity of the condenser 801 according to equation 4 above eliminates the difference in the delays of the rising and falling signals at the schmitt trigger thereby allowing the system to accommodate upgrades to high speed data transfer additionally the schmitt trigger of the present embodiment is one in which the condenser 801 which has been added to the circuit has the same structure as that which is used with conventional circuits therefore the present embodiment can be formed on the heater board using the same manufacturing techniques as are used conventionally thus keeping cost increases associated with the present embodiment to a minimum a description will now be given of a printhead according to a third embodiment such description concentrates on the distinctive features of the third embodiment and so a description of elements of the third embodiment that are identical to those of the first and second embodiments described above is omitted fig1 is a circuit diagram showing the structure of a schmitt trigger of the printhead according to the third embodiment of the present invention as a means of adjusting the delay of the rising and falling waveform signals at the schmitt trigger depicted in fig2 a the present embodiment is provided with a resistor 901 connected to the output of inverter 100 assuming the on resistance of the resistor 901 is r 901 and the on resistance and the input capacity of the other components are the same as those for the first embodiment as described above then the rising waveform signal delay tr at the schmitt trigger of the present embodiment is tr u221d r 100 r 901 u00d7.