Printhead with malfunction prevention function and printing apparatus using it
AssigneeCanon Kabushiki Kaisha
InventorHiroyuki Maru
Life of this patent
Estimating the term…
Abstract
A printhead and a printing apparatus using the printhead capable of protecting the printhead without causing malfunction in the printhead even if electrical connection between the printing apparatus and the printhead is cut off for some reason. A VDD monitor 400 monitors a voltage supplied via a pad 315 to a cutoff-function added level converter function 121 to perform drive control on a heater 301. The operation of a power transistor 302 to drive the heater 301 is forcefully turned OFF in accordance with the result of monitoring.
Claims14
A printhead, supplied with a control signal, print data and electric power supplied via a plurality of electrical contacts, for performing printing operations, comprising:
- a printing element;
- a first contact that inputs a voltage to drive said printing element;
- a control circuit that performs drive control on said printing element;
- a second contact that inputs a voltage to drive said control circuit;
- a monitoring circuit that monitors the control circuit drive voltage input at said second contact;
- and
- a protection circuit that stops driving of said printing element by said control circuit, in accordance with the result of monitoring by said monitoring circuit.
A printhead, supplied with a control signal, print data and electric power supplied via a plurality of electrical contacts, for performing printing operations, comprising:
- a printing element;
- a first contact that inputs a voltage to drive said printing element;
- a control circuit that performs drive control on said printing element;
- a second contact that inputs a voltage to drive said control circuit;
- a monitoring circuit that monitors the voltage in said second contact;
- and
- a protection circuit that stops driving of said printing element by said control circuit, in accordance with the result of monitoring by said monitoring circuit,
- wherein said protection circuit includes an analog switch and a PMOS transistor, said analog switch cuts off an output from said control circuit in accordance with the result of monitoring from said monitoring circuit, and said PMOS transistor forcefully turns off an output to said printing element.
A printhead, supplied with a control signal, print data and electric power supplied via a plurality of electrical contacts, for performing printing operations, comprising:
- a printing element;
- a first contact that inputs a voltage to drive said printing element;
- a control circuit that performs drive control on said printing element;
- a second contact that inputs a voltage to drive said control circuit;
- a monitoring circuit that monitors the voltage in said second contact;
- and
- a protection circuit that stops driving of said printing element by said control circuit, in accordance with the result of monitoring by said monitoring circuit,
- wherein said protection circuit includes a switch comprising a pair of a first PMOS transistor and an NMOS transistor and a second PMOS transistor, said switch comprising the pair of said first PMOS transistor and said NMOS transistor cuts off an output from said control circuit in accordance with the result of monitoring from said monitoring circuit, and said second PMOS transistor forcefully turns off an output to said printing element.
A printhead, supplied with a control signal, print data and electric power supplied via a plurality of electrical contacts, for performing printing operations, comprising:
- a printing element;
- a first contact that inputs a voltage to drive said printing element;
- a control circuit that performs drive control on said printing element;
- a second contact that inputs a voltage to drive said control circuit;
- a monitoring circuit that monitors the voltage in said second contact;
- and
- a protection circuit that stops driving of said printing element by said control circuit, in accordance with the result of monitoring by said monitoring circuit,
- wherein said monitoring circuit operates by the voltage inputted from said first contact, and said monitoring circuit comprises a plurality of inverter circuits connected to said second contact and a pull-down resistor connected to said second contact.
Dependencies are inferred from the claim text.