JP2005027160A - Voltage supply unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a semiconductor switch element, a driver IC or the like from being broken when a power supply is turned on. <P>SOLUTION: An FET31 is provided. The FET takes in V<SB>CC</SB>voltage from a V<SB>CC</SB>voltage source, and the V<SB>CC</SB>voltage is outputted when the FET is actuated. The collector of the bipolar transistor 32 is connected to a gate of the FET through a resistor 33, with its emitter being grounded. A V<SB>DD</SB>voltage from a V<SB>DD</SB>voltage source is inputted in the base of the bipolar transistor 32 through a resistor 34. The V<SB>CC</SB>voltage outputted from the FET is inputted in a three-terminal regulator 35. The three-terminal regulator 35 controls for stepping down the inputted V<SB>CC</SB>voltage, to output a V<SB>AA</SB>voltage. The V<SB>CC</SB>voltage outputted from the FET is supplied to a head drive circuit, and the V<SB>AA</SB>voltage outputted from the three-terminal regulator 35 is supplied to an ink-jet head. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a voltage supply device that supplies three types of voltages.
[0002]
[Prior art]
For example, as shown in FIG. 4, a driving device that drives an inkjet head that uses a piezoelectric member as an ink discharge driving means includes a processing unit 1 that processes an input signal with a logical function, and a semiconductor switching element 2 such as an FET. A load unit that applies a _VAA voltage to the electrodes of the piezoelectric member by a switching operation and a drive unit 3 that switches the semiconductor switch element 2 in response to a signal from the processing unit 1 are provided. Then, the processing unit 1 is operated by the input signal, the driving unit 3 is operated by this operation, the semiconductor switching element 2 is switched by the operation of the driving unit 3, and the control for applying the _VAA voltage to the electrode of the piezoelectric member is performed. As a result, the piezoelectric member is deformed and ink is ejected from the ink chamber.
[0003]
In such a driving apparatus, the processing unit 1 is supplied V _DD voltage of, for example, about 5V as the power supply voltage, V _CC voltage of about 30~40V example as a power supply voltage is supplied to the drive unit 3, the piezoelectric member is V _AA voltage degree exceeding 20V for example are supplied to the electrodes.
[0004]
In some cases, first, + 5V is supplied to the control circuit, and when the supply voltage becomes + 4V or more, + 22V power is applied to the head as a power supply voltage (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-191615
[Problems to be solved by the invention]
In the driving device of FIG. 4, when the V _CC voltage is supplied to the V _DD voltage is not supplied, the level of line A becomes unstable, also, V _AA voltage is supplied to the V _CC voltage is not supplied Then, the level of line B becomes unstable. As described above, when the levels of the lines A and B may become unstable, an overcurrent flows through the semiconductor switch element 2 and the semiconductor switch element may be destroyed.
[0007]
Accordingly, the present invention provides a power supply voltage in the related system of _{V DD <V AA <V CC} , a V _DD voltage to the processing unit of the data or signals having a logic function and operation function, and the like, Ya semiconductor switching element supply V _CC voltage is the V _AA voltage to the load unit which is driven by the driver IC and the like, to the driving unit for driving the semiconductor switching element and the driver IC or the like in response to signals or data from the processing unit in those, V _CC voltage rises after the rise of always V _DD voltage, V _AA voltage is controlled to rise after a rise of the V _CC voltage, thereby, the semiconductor switching elements and a driver IC or the like is destroyed A voltage supply device capable of preventing the above is provided.
[0008]
[Means for Solving the Problems]
The present invention relates to a data or signal processing unit having a logic function or an arithmetic function, a load unit driven by a semiconductor switch element or a driver IC, and a semiconductor switch element or driver IC in response to a signal or data from the processing unit. with the driving unit for driving the like, and supplies the V _DD voltage to each processor, to supply the high V _AA voltage than V _DD voltage to the load unit, V _AA for driver in the voltage supplying device for supplying a high _{V CC} voltage than the _voltage, a voltage from the _{V CC} voltage supply uptake, a first switch means for outputting the _{V CC} voltage by the oN _operation, the _{V DD} voltage from _{V DD} voltage source second switching means and the first step-down means for the V _CC voltage outputted from the switch unit the step-down control and outputs a V _AA voltage that turns on operating a first switching means in response to input Certain to be equipped.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a share mode type ink jet head driving apparatus.
[0010]
As shown in FIG. 1, there is provided a drive pulse generation circuit 12 as a processing unit that has a logical function, an arithmetic function, etc., and generates a drive pulse for driving the inkjet head 11 based on input print data. For example, a 5 V V _DD voltage is supplied to the drive pulse generation circuit 12 as a power source. The drive pulse generated from the drive pulse generation circuit 12 is supplied to the head drive circuit 13 constituting the drive unit.
[0011]
As shown in FIG. 2, the inkjet head 11 uses two piezoelectric members 21 and 22 which are bonded and fixed with an adhesive and laminated on a substrate 23 made of a ceramic material. Yes. Then, a plurality of grooves having the same width, the same depth, and the same length are formed in parallel at a constant interval by cutting with respect to the piezoelectric members 21 and 22, and an electrode 24 is provided in each groove. Is covered with a top plate 25 to form an ink chamber 26. Each of the piezoelectric members 21 and 22 is formed of a piezoelectric element made of, for example, piezoelectric ceramic, and is polarized in a direction opposite to each other in the plate thickness direction as indicated by arrows in the drawing. An orifice plate (not shown) is attached to the front surface of each ink chamber 26, and an ink discharge port 27 is provided in the orifice plate corresponding to each ink chamber 26.
[0012]
The head drive circuit 13 drives a semiconductor switching element such as a transistor, a driver IC, and the like, and accordingly, a drive voltage is applied between the electrodes 24 provided in each ink chamber 26 of the inkjet head 11 according to a drive pulse. It is designed to be applied. For example, a positive voltage is applied between the electrode 24 of the ink chamber 26 that performs ink ejection and the electrode 24 of the ink chamber 26 on both sides thereof, and then becomes negative. By applying a voltage, the walls on both sides of the ink chamber 26 that ejects ink are once deformed outward and then inward. As a result, pressure is applied to the ink in the ink chamber 26, and the ink is ejected from the ink ejection port 27.
[0013]
Wherein the ink jet head 11 is greater than _{V DD} voltage, for example _{V AA} voltage of 22V is supplied as a power supply. Also, the greater than _{V AA} voltage to the head drive circuit 13, for example, _{V CC} voltage of 36.5V is supplied as a power supply.
The supply of the _VAA voltage applied to the inkjet head 11 and the _VCC voltage applied to the head drive circuit 13 is performed by a voltage supply device shown in FIG.
[0014]
That includes a FET (field effect transistor) 31 as a first switching means, it becomes the _{V CC} voltage from the _{V CC} voltage supply to the FET31 uptake, so as to output the _{V CC} voltage when the FET31 is turned on ing. Further, an NPN-type bipolar transistor 32 is provided as a second switch means, the collector of the bipolar transistor 32 is connected to the gate of the FET 31 via a resistor 33, and the emitter thereof is grounded. _Then, a _{V DD} voltage from _{V DD} voltage source, is input to the base of the bipolar transistor 32 via a resistor 34.
[0015]
The _{V CC} voltage outputted from the FET 31, is input to the three-terminal regulator 35 constituting the step-down unit. The three-terminal regulator 35 is arranged to output a V _AA voltage by the step-down control of the V _CC voltage input. Then, supply _{V CC} voltage outputted from the FET31 to the head drive circuit 13, and supplies the _{V AA} voltage outputted from the three-terminal regulator 35 to the inkjet head 11.
[0016]
In such a configuration, if the V _DD voltage is not generated from the V _DD voltage source, the bipolar transistor 32 is not turned on, so that the FET 31 is kept off. _Thus, with no _{V DD} voltage is generated from _{V DD} voltage source, _{never V CC} voltage be _{V CC} voltage is generated from the _{V CC} voltage supply above is supplied to the head driving circuit 13.
[0017]
That is, _{first, V DD} voltage is generated from _{V DD} voltage source, _{V DD} voltage is supplied to the drive pulse generation circuit 12. Then, the bipolar transistor 32 is turned on by the generation of the V _DD voltage. In this _state, when the _{V CC} voltage is generated from the _{V CC} voltage source, FET 31 is turned _{on, V CC} voltage is supplied to the head drive circuit 13. If V _CC voltage is generated, _{V AA} voltage is generated by a 3-terminal regulator 35, it is supplied to the inkjet head 11.
[0018]
Thus, the supply of the V _AA voltage to the ink jet head 11 is performed after the supply of the V _CC voltage to the head drive circuit 13 is performed.
_Thus, in supplies _{V DD voltage, V CC voltage,} three voltage of _{V AA} voltage as a power source, the power source at the time of rise of, _firstly, is supplied _{V DD} voltage, _{subsequently, V CC} voltage supply And finally the order in which the V _AA voltage is supplied is ensured. Accordingly, there is no situation in which the device is destroyed due to an overcurrent flowing through the semiconductor switching device, the driver IC, or the like at the time of startup by supplying the _VAA voltage first. That is, it is possible to reliably prevent the semiconductor switching element, the driver IC, and the like from being destroyed when the power supply is turned on.
[0019]
Further, when the power is shut off, the _VAA voltage and the _VCC voltage fall substantially simultaneously, so that the semiconductor switching element and the driver IC are not adversely affected. Note that since the voltage level of the V _DD voltage is low, there is no possibility of adversely affecting the elements and the like even if the on state is continued.
[0020]
In this embodiment, the present invention is applied to a share mode type ink jet head driving apparatus. However, the present invention is not limited to this. That is, three types of voltages corresponding to the V _DD voltage, the _VCC voltage, and the V _AA voltage are used as a power supply, and the V _DD voltage is applied to a data or signal processing unit having a logic function, an arithmetic function, etc. The _VAA voltage is applied to a load unit driven by a driver IC or the like, and the V _CC voltage is applied to a drive unit that drives a semiconductor switch element or a driver IC in response to a signal or data from a processing unit. Applicable to what is supplied.
[0021]
【The invention's effect】
As described above in detail, according to the present invention, the power supply voltage in the relationship of V _DD <V _AA <V _CC is applied to the V _DD voltage for the data or signal processing unit having a logic function or an arithmetic function. _VAA voltage for a load unit driven by a semiconductor switch element, a driver IC, etc., and a drive unit for driving the semiconductor switch element, driver IC, etc. in response to a signal or data from a processing unit in what is to supply _{V CC} voltage, _{V CC} voltage rises after the rise of always _{V DD voltage,} controlled to _{V AA} voltage rises after the rise of the _{V CC} voltage, thereby, the semiconductor switching element and the driver IC Thus, it is possible to provide a voltage supply device that can prevent damage to the like.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of an ink jet head driving apparatus according to an embodiment of the present invention.
FIG. 2 is a partial cross-sectional view showing a configuration of an inkjet head according to the embodiment.
FIG. 3 is a circuit configuration diagram of the voltage supply device according to the embodiment;
FIG. 4 is a diagram showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Inkjet head (load part), 12 ... Drive pulse generation circuit (processing part), 13 ... Head drive circuit (drive part), 31 ... FET (first switch means), 32 ... Bipolar transistor (second switch) Means), 35... Three-terminal regulator (step-down means).

Claims (2)

Data and signal processing units having logic functions and arithmetic functions, load units driven by semiconductor switch elements and driver ICs, and the semiconductor switch elements and driver ICs in response to signals and data from the processing units A V _DD voltage is supplied to the processing unit, a V _AA voltage higher than the V _DD voltage is supplied to the load unit, and a V A voltage higher than the V _DD voltage is supplied to the driving unit. _In a voltage supply device that supplies a _VCC voltage higher than the _AA voltage,
Uptake voltage from V _CC voltage source, a first switch means for outputting the V _CC voltage by the ON operation, the ON operation of the first switching means in response to the input of the V _DD voltage from V _DD voltage source a second switching means the voltage supplying device, characterized in that said V _CC voltage output from the first switch means down control to and a step-down means for outputting the V _AA voltage. The load unit is composed of an ink jet head using a piezoelectric member as an ink discharge driving unit, and is configured to apply a _VAA voltage to the electrode of the piezoelectric member by an operation of a semiconductor switch element, a driver IC, or the like. The voltage supply apparatus according to claim 1.

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