In order to adapt a thermal head for a thermal printer to a raised speed, the thickness .delta.(.mu.m) of a heat accumulating layer in the head is set at: ##EQU1## where k: temperature conductivity of the heat accumulating layer, t.sub.p : heating duration of the thermal head, and t.sub.O : printing cycle of the thermal head.

In an ink ejection type recording device in which expansion of bubble ejects an ink droplet from a nozzle toward a recording medium, a heater formed in an ink channel is applied with a pulse of voltage by a driver circuit. The pulse of voltage is determined so that the surface of the heater in direct contact with the water-based ink is rapidly heated to a temperature causing to invoke caviar-wise nucleation of the ink that is in direct contact with the surface of the heater. Expanding bubbles resulting from the caviar-wise nucleation ejects an ink droplet from the nozzle, wherein the heater is heated at a heating speed in a range from 1.times.10.sup.8 .degree. C./sec to 5.times.10.sup.8 .degree.C./sec, and the surface of the heater is heated up from a room temperature to a temperature substantially equal to 320 C within a period of time ranging from 0.6 to 3 .mu.sec. By heating the heater under these conditions, the ink in contact with the heater starts boiling with a high boiling pressure, the generated bubble has a large volume, and thus the bubble can generate pressure sufficiently large to eject the ink droplet.

A plurality of heaters are provided on a silicon substrate in a plurality of individual ink channels. Each heater is constructed from a thin-film resistor and a thin-film conductor. The thin-film resistor is formed with an electrical insulation layer at its upper surface. The electrical insulation layer is formed through subjecting the thin-film resistor to a high-temperature thermal oxidation process. The thin-film resistor formed with the electrical insulation layer may be covered with an additional insulation layer of a thickness substantially equal to the thin-film resistor.

An ink ejection printer includes an ink channel filled with ink, a nozzle which brings the ink channel into fluid connection with an outside atmosphere, and a thermal resistor formed in the ink channel near the nozzle. The thermal resistor received a pulse of voltage, whereupon the thermal resistor rapidly heats so that a portion of the ink in the ink channel is rapidly vaporized by subcool boiling, which is caused by swing nucleation, to produce a bubble, expansion of the bubble ejecting an ink droplet from the nozzle. With the thermal resistor, boiling starts within 2 .mu.S after application of the pulse of voltage begins. The pulse of voltage is applied to the thermal resistor for a duration of 3 .mu.S or less. The bubble generated by application of the pulse of voltage to the thermal resistor disappears without the thermal resistor generating secondary bubbles. The bubble generated by application of the pulse of voltage of the thermal resistor disappears within 11 .mu.S after application of the pulse. Energy required to generate the bubble is 4 .mu.J/50.times.50 .mu.m.sup.2 or less.

In thin layer resistors comprising a patch of a layer of resistive material on an insulating substrate and means at spaced apart locations on the patch, the resistive material is formed of 95 to 99.5 wt % of a zero valence metal and between 5 and 0.5 wt % of a dielectric material.