Liquid discharge head unit and liquid discharge apparatus

Abstract

The present disclosure provides a liquid ejection head unit and a liquid ejection apparatus. The liquid ejection head unit includes: a liquid ejection head including a plurality of pressure chambers, a plurality of piezoelectric elements, and a drive wiring for applying a voltage for driving the piezoelectric elements to the piezoelectric elements; a first detection resistor provided corresponding to a first piezoelectric element group; a second detection resistor provided corresponding to a second piezoelectric element group; a power supply circuit for causing a current to flow to the first detection resistor and the second detection resistor; a voltage detection circuit for detecting a voltage; and a switching circuit capable of switching between a first state in which the voltage detection circuit can detect a voltage generated in the first detection resistor by a current flowing from the power supply circuit and a second state in which the voltage detection circuit can detect a voltage generated in the second detection resistor by a current flowing from the power supply circuit.

Claims

1. A liquid ejector head unit, comprising: A liquid ejector head includes a pressure chamber substrate, multiple piezoelectric elements, and drive wiring. The pressure chamber substrate is provided with multiple pressure chambers, and the drive wiring is used to apply a voltage to the piezoelectric elements for driving the piezoelectric elements. The first sensing resistor is arranged in a manner corresponding to the first group of piezoelectric elements among the plurality of piezoelectric elements, and is formed of the same material as the electrodes of the piezoelectric elements or the drive wiring; The second sensing resistor is configured to correspond to a second piezoelectric element group that is different from the first piezoelectric element group among the plurality of piezoelectric elements, and is formed of the same material as the electrodes of the piezoelectric element or the drive wiring; A power supply circuit for causing current to flow to the first sensing resistor and the second sensing resistor; A voltage detection circuit, used to detect voltage; A switching circuit is provided to switch between a first state and a second state. The first state is in which the voltage detection circuit can detect the voltage generated in the first detection resistor by the current flowing from the power supply circuit. The second state is in which the voltage detection circuit can detect the voltage generated in the second detection resistor by the current flowing from the power supply circuit. When the stacking direction of the pressure chamber substrate and the piezoelectric element is set as the stacking direction, the first detection resistor and the piezoelectric body of the first piezoelectric element group are arranged at the same position in the stacking direction, and the second detection resistor and the piezoelectric body of the second piezoelectric element group are arranged at the same position in the stacking direction.

2. The liquid ejector head unit as claimed in claim 1, wherein, It also has multiple liquid ejection heads, The plurality of liquid nozzles includes a first liquid nozzle and a second liquid nozzle that is different from the first liquid nozzle. The first detection resistor is disposed in the first liquid nozzle. The second detection resistor is disposed in the second liquid nozzle.

3. The liquid ejector unit as described in claim 1, wherein, The first detection resistor and the second detection resistor are disposed in the liquid nozzle.

4. The liquid ejector head unit as described in any one of claims 1 to 3, wherein, It also has: The first path electrically connects the power supply circuit and the voltage detection circuit via the first detection resistor; The second path electrically connects the power supply circuit and the voltage detection circuit via the second detection resistor; The third path electrically connects the power supply circuit and the voltage detection circuit without passing through the first detection resistor. The fourth path electrically connects the power supply circuit and the voltage detection circuit without passing through the second detection resistor.

5. The liquid ejector unit as described in claim 4, wherein, have: A first switch is positioned between the first detection resistor and the voltage detection circuit midway through the first path. A second switch is positioned midway through the second path between the second detection resistor and the voltage detection circuit. The switching circuit switches to the first state by setting the first switch to the connected state and the second switch to the disconnected state, and switches to the second state by setting the second switch to the connected state and the first switch to the disconnected state.

6. The liquid ejector head unit as claimed in claim 5, wherein, The on-resistance of the first switch is less than 1 / 100 of the resistance value of the first detection resistor. The on-resistance of the second switch is less than 1 / 100 of the resistance value of the second detection resistor.

7. The liquid ejector unit as claimed in claim 6, wherein, The third path and the fourth path are the same path.

8. The liquid ejector unit as claimed in claim 4, wherein, The first path and the third path are the same path from the power supply circuit to the first branch point, but are different paths from the first branch point to the voltage detection circuit. The second path and the fourth path are the same path from the power supply circuit to the second branch point, but different paths from the second branch point to the voltage detection circuit. The liquid ejector unit also includes a third switch and a fourth switch. The third switch is located between the first branch point in the middle of the third path and the voltage detection circuit, and the fourth switch is located between the second branch point in the middle of the fourth path and the voltage detection circuit. The switching circuit switches to the first state by setting the third switch to the connected state and the fourth switch to the disconnected state, and switches to the second state by setting the fourth switch to the connected state and the third switch to the disconnected state.

9. The liquid ejector unit as claimed in claim 8, wherein, It also has a fifth switch and a sixth switch, the fifth switch being disposed between the power circuit and the first branch point midway through the first path, and the sixth switch being disposed between the power circuit and the second branch point midway through the second path. The switching circuit switches to the first state by setting the fifth switch to the connected state and the sixth switch to the disconnected state, and switches to the second state by setting the sixth switch to the connected state and the fifth switch to the disconnected state.

10. The liquid ejector unit as claimed in claim 9, wherein, The switching circuit causes the third switch and the fifth switch to be linked together to switch the connection state and the disconnection state of the third switch and the fifth switch, and causes the fourth switch and the sixth switch to be linked together to switch the connection state and the disconnection state of the fourth switch and the sixth switch.

11. The liquid ejector head unit as claimed in any one of claims 8 to 10, wherein, The on-resistance of the third switch is less than 1 / 100 of the resistance value of the first detection resistor. The on-resistance of the fourth switch is less than 1 / 100 of the resistance value of the second detection resistor.

12. The liquid ejector unit as claimed in claim 4, wherein, The voltage detection circuit includes: The first differential amplifier circuit has one input terminal connected to the first path and the second path, and the other input terminal connected to the third path and the fourth path. The fifth path connects the output terminal of the first differential amplifier circuit and the input terminal of the voltage detection circuit.

13. The liquid ejector unit as claimed in claim 1, wherein, The power supply circuit is a constant current circuit that allows a constant current to flow to the first sensing resistor and the second sensing resistor.

14. The liquid ejector unit as claimed in claim 1, wherein, It also includes a sixth path, which electrically connects the voltage detection circuit and the power supply circuit and is used to output the reference voltage of the voltage detection circuit. The power supply circuit extracts a current proportional to the reference voltage that is input via the sixth path.

15. The liquid ejector unit as claimed in claim 1, wherein, It also includes a third sensing resistor, which is configured to correspond to a third piezoelectric element group that is different from the first and second piezoelectric element groups, and is formed of the same material as the electrodes of the piezoelectric elements or the drive wiring. The switching circuit can be switched to a third state, in which the voltage detection circuit can detect the voltage generated in the third detection resistor by the current flowing from the power supply circuit.

16. The liquid ejector unit as claimed in claim 1, wherein, The resistance value of the first detection resistor is more than 0.5 times and less than 1.5 times the resistance value of the second detection resistor.

17. The liquid ejector unit as claimed in claim 1, wherein, The temperature of the pressure chamber is obtained using the voltage generated in the first sensing resistor by the current flowing from the power supply circuit, as detected by the voltage detection circuit, and the temperature of the pressure chamber is obtained using the voltage generated in the second sensing resistor by the current flowing from the power supply circuit, as detected by the voltage detection circuit.

18. The liquid ejector unit as claimed in claim 1, wherein, It also includes a wiring board that is electrically connected to the liquid ejector head. The switching circuit is configured on the wiring board.

19. A liquid ejector head unit, comprising: A liquid ejector head having multiple pressure chambers, multiple piezoelectric elements, and drive wiring, the drive wiring being used to apply a voltage to the piezoelectric elements for driving the piezoelectric elements; The first sensing resistor is arranged in a manner corresponding to the first group of piezoelectric elements among the plurality of piezoelectric elements, and is formed of the same material as the electrodes of the piezoelectric elements or the drive wiring; The second sensing resistor is configured to correspond to a second piezoelectric element group that is different from the first piezoelectric element group among the plurality of piezoelectric elements, and is formed of the same material as the electrodes of the piezoelectric element or the drive wiring; A power supply circuit for causing current to flow to the first sensing resistor and the second sensing resistor; A voltage detection circuit, used to detect voltage; A switching circuit is provided to switch between a first state and a second state. The first state is in which the voltage detection circuit can detect the voltage generated in the first detection resistor by the current flowing from the power supply circuit. The second state is in which the voltage detection circuit can detect the voltage generated in the second detection resistor by the current flowing from the power supply circuit. The power supply circuit also includes an operational amplifier, a power supply resistor, and a second differential amplifier circuit. The power supply resistor is connected to the output terminal of the operational amplifier, the input terminals of the two ends of the second differential amplifier circuit are connected to the two ends of the power supply resistor, and the output terminal of the second differential amplifier circuit is connected to one of the input terminals of the operational amplifier.

20. A liquid ejection device, comprising: The liquid ejector head unit according to any one of claims 1 to 19, The control unit controls the ejection action of the liquid ejection head unit.

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