Inkjet recording head and inkjet recording apparatus having the same

Abstract

An inkjet recording head includes a passage communicating with a discharge port for discharging ink, a discharging heater provided in the passage for generating energy to discharge ink from the discharge port, and a detecting unit provided in the passage for detecting a temperature of ink that changes in accordance with heat energy generated by the detecting unit and a flow of ink in the passage.

1 . An inkjet recording head comprising:
 a passage communicating with a discharge port for discharging ink;   an energy generating element, provided in said passage, for generating energy to discharge ink from the discharge port; and   a detecting unit, provided in said passage, for detecting a temperature of ink that changes in accordance with heat energy generated by said detecting unit and a flow of ink in said passage.   
   
   
       2 . The inkjet recording head according to  claim 1 ,
 wherein said energy generating element is provided in a portion of said passage facing the discharge port.   
   
   
       3 . The inkjet recording head according to  claim 1 ,
 wherein said passage is formed by coupling a heater board, having a protective insulating film and a cavitation-resistant film, to a nozzle forming member.   
   
   
       4 . The inkjet recording head according to  claim 3 ,
 wherein said detecting unit is provided at a portion of the heater board between the discharge port and an ink supply port through which the ink is supplied into said passage.   
   
   
       5 . The inkjet recording head according to  claim 3 ,
 wherein said detecting unit is provided in the nozzle forming member.   
   
   
       6 . The inkjet recording head according to  claim 5 ,
 wherein the nozzle forming member is formed of silicon.   
   
   
       7 . The inkjet recording head according to  claim 1 ,
 wherein the heat energy generated by said detecting unit does not generate a bubble in the ink.   
   
   
       8 . The inkjet recording head according to  claim 1 ,
 wherein said detecting unit detects a voltage corresponding to a resistance that changes in accordance with temperature.   
   
   
       9 . The inkjet recording head according to  claim 1 ,
 wherein said detecting unit comprises a heating element configured to generate the heat energy, and first and second resistors arranged symmetrically with respect to said heating element, the first and second resistors having resistances that change in according with the temperature.   
   
   
       10 . The inkjet recording head according to  claim 9 ,
 wherein the heating element generates the heat energy and is used to detect a voltage corresponding to a difference between the resistances of the first and second resistors.   
   
   
       11 . An inkjet recording apparatus comprising:
 an inkjet recording head comprising a passage communicating with a discharge port for discharging ink, an energy generating element, provided in the passage, for generating energy to discharge ink from the discharge port, and a detecting unit, provided in the passage, for detecting a temperature of ink that changes in accordance with heat energy generated by the detecting unit and a flow of ink in the passage; and   a control unit configured to control driving of said inkjet recording head.   
   
   
       12 . The inkjet recording apparatus according to  claim 11 ,
 wherein the detecting unit detects a voltage corresponding to a resistance that changes in accordance with temperature, and   wherein said control unit judges a discharging state of ink from the discharge port on the basis of the detected voltage.   
   
   
       13 . The inkjet recording apparatus according to  claim 11 ,
 wherein said inkjet recording head comprises a plurality of passages and discharge ports, with an energy generating element and a detecting unit provided in each of the passages.   
   
   
       14 . A method for detecting defective discharging of an inkjet recording head, comprising the steps of:
 discharging ink by supplying a driving pulse to an energy generating element to generate a bubble in ink in a passage communicating with an ink discharge port;   applying at least one pulse to a flow sensor;   measuring an output voltage from the flow sensor; and   comparing the output voltage from the flow sensor with a threshold value to determine a level of ink flow in the passage.   
   
   
       15 . The method for detecting defective discharging of an inkjet recording head according to  claim 14 ,
 wherein two pulses are applied to the flow sensor when a driving pulse is applied to the energy generating element.