Element substrate, printhead, and printing apparatus
AssigneeCanon Kabushiki Kaisha
InventorsRyo Kasai, Nobuyuki Hirayama, Makoto Takagi
Life of this patent
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Abstract
A recent inkjet printing apparatus includes a large-capacitance capacitor to stabilize a heater power supply. The presence of this capacitor requires a long time to drop the heater voltage at the time of power shutdown or the like. For this reason, an unwanted heater current may flow during the drop. To solve this problem, in this embodiment, a high voltage logic circuit is provided near a printing element, and a terminal is provided so that a signal can directly be input to this circuit. Heater driving control is performed via the terminal. This makes it possible to reliably control the heater regardless of the logic power supply state even if the logic voltage abruptly drops at the time of power shutdown or the like.
Claims13
An element substrate including a plurality of printing elements to which a first voltage is applied, a plurality of driving elements provided in correspondence with the plurality of printing elements and configured to drive the plurality of printing elements, a plurality of logic circuits configured to generate, based on an externally input signal, a selection signal used to select and drive the plurality of printing elements, and a plurality of first level converters provided in correspondence with the plurality of logic circuits and configured to boost a logic voltage having a second voltage lower than the first voltage of the selection signal, comprising:
- a pad configured to externally receive a detection signal indicating detection of drop of the logic voltage;
- a second level converter configured to receive the detection signal via said pad and boost the detection signal;
- and
- a plurality of high voltage logic circuits provided in correspondence with the plurality of driving elements and the plurality of first level converters and configured to receive the boosted selection signals respectively output from the plurality of first level converters and the detection signal boosted by said second level converter, perform a logical operation of the boosted selection signals and the boosted detection signal and, output a result of the logical operation, and drive the plurality of driving elements,
- wherein when the detection signal is input, said plurality of high voltage logic circuits inhibit driving of the plurality of driving elements regardless of the boosted selection signals.
Dependencies are inferred from the claim text.