Medical instrument

A medical instrument includes a multilayer wiring board having first, second and third wirings, a fourth wiring formed in a first wiring layer, and a fifth wiring formed in a second wiring layer. A first via conductor electrically connects the third and fifth wirings. A second via conductor electrically connects the fourth and fifth wirings. The medical instrument further includes first and second transistors, a second transistor, and a capacitor mounted on the first wiring layer side of the multilayer wiring board. The drain and source electrodes of the first transistor are electrically connected to the first and second wirings, respectively. The drain electrode of the second transistor is electrically connected to the second wiring. The source electrode of the second transistor is electrically connected to the third wiring. The first and second electrodes of the capacitor are electrically connected to the first and fourth wirings, respectively.

This application claims priority to Japanese Patent Application Nos. 2012-196552 filed on Sep. 6, 2012 and Japanese Patent Application No. 2012-232219 filed on Oct. 19, 2012. The entire disclosure of Japanese Patent Application Nos. 2012-196552 and 2012-232219 is hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a semiconductor device, a medical instrument, and the like.

2. Related Art

Similar to an ejecting head which is mounted in an ink jet printer, there are many actuators constituted by a capacitive load, such as a piezoelectric element. In order to drive an actuator as a capacitive load, a drive signal having a certain level of power is required. Accordingly, a drive waveform signal as a source of a drive signal is power-amplified to generate a drive signal. When an analog drive waveform signal is power-amplified in an analog form to directly generate an analog drive signal, significant power loss occurs and power efficiency is degraded. Accordingly, technology for power amplification using a so-called class D amplifier has been suggested.

A medical instrument which uses a fluid transport apparatus, in which a plurality of rollers are provided on a concentric circle of a rim portion of a rotor, a tube is mounted such that a fluid flows between the tube and a tube receiving member, and when the rotor rotates, the rollers sequentially press the tube to cause the fluid to flow, is known. A medical instrument which uses a fluid transport apparatus, in which the tube is pressed to cause the fluid to flow using a plurality of pressing elements (for example, piezoelectric elements) instead of a plurality of rollers, or a medical instrument which uses a fluid ejecting apparatus using a piezoelectric element is also known.

For example, when a switching circuit, such as a class D amplifier, is used as a circuit which drives a plurality of piezoelectric elements, in order to suppress ringing of an output voltage, in general, a bypass capacitor is arranged between a power supply potential and a ground potential (for example, JP-A-2011-187809). In an ink jet printer, the occurrence of ringing leads to the occurrence of EMI noise. As a result, the amount of ink to be ejected varies, thereby causing interference with improvement in printing quality. In a medical instrument using a fluid transport apparatus or a fluid ejecting apparatus, the occurrence of ringing leads to the occurrence of EMI noise, causing interference with the operation of the apparatus itself or peripherals. For example, in a medical instrument using a fluid ejecting apparatus, the occurrence of EMI noise with ringing causes variation in the amount of fluid to be ejected.

In order to suppress ringing, it is important to decrease parasitic inductance in a loop having two transistors and a bypass capacitor of a switching circuit. In order to decrease parasitic inductance, it is necessary to decrease the area of a loop having two transistors and a bypass capacitor of a switching circuit. The inter-electrode distance of the capacitor increases with an increase in capacitance of the capacitor, and thus, in the arrangement of the capacitor described in JP-A-2011-187809, an increase in capacitance of the capacitor results in an increase in the area of the loop. For this reason, there is a limitation to suppress ringing, that is, to improve printing quality or to stably transport a fluid.

SUMMARY

An advantage of some aspects of the invention is that it provides a liquid ejecting apparatus and a printing apparatus capable of ejecting a liquid with high precision, a switching circuit in which the occurrence of ringing is suppressed, a medical instrument which stably handles a fluid, and the like.

Application Example 1

This application example is directed to a liquid ejecting apparatus including a capacitive load drive circuit, in which the capacitive load drive circuit includes a drive waveform generator which generates a drive waveform signal, a modulator which performs pulse modulation on the drive waveform signal to generate a modulated signal, a multilayer wiring board having a first wiring layer and a second wiring layer, and a first transistor, a second transistor, and a capacitor mounted on the first wiring layer side of the multilayer wiring board, a switching circuit which receives the modulated signal on the gate electrode of the first transistor and the gate electrode of the second transistor, and generates an amplified digital signal as a signal obtained through power amplification on the modulated signal, and a low pass filter which smoothes the amplified digital signal to generate a drive signal, the multilayer wiring board has a first wiring, a second wiring, a third wiring, and a fourth wiring formed in the first wiring layer, a fifth wiring formed in the second wiring layer, a first via conductor electrically connecting the first wiring and the fifth wiring, and a second via conductor electrically connecting the fourth wiring and the fifth wiring, the drain electrode of the first transistor is electrically connected to the first wiring, the source electrode of the first transistor is electrically connected to the second wiring, the drain electrode of the second transistor is electrically connected to the second wiring, the source electrode of the second transistor is electrically connected to the third wiring, the first electrode of the capacitor is electrically connected to the fourth wiring, and the second electrode of the capacitor is electrically connected to the third wiring.

According to this application example, the first transistor, the second transistor, and the capacitor are all mounted on the first wiring layer side of the multilayer wiring board, and a loop is electrically formed through the fifth wiring formed in the second wiring layer. Accordingly, even if the capacitor increases, it is possible to suppress an increase in the area of the electrical loop including the first transistor, the second transistor, and the capacitor compared to a case where the capacitor is mounted on the second wiring layer side of the multilayer wiring board. It is also possible to suppress an increase in the area of the electrical loop including the first transistor, the second transistor, and the capacitor compared to a case where all wirings are formed in the same wiring layer. That is, it is possible to suppress an increase in parasitic inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit. Therefore, it is possible to implement a liquid ejecting apparatus which can eject a liquid with high precision.

Since the first transistor, the second transistor, and the capacitor are all mounted on the first wiring layer side of the multilayer wiring board, it is possible to easily perform mounting.

Since there are no elements arranged on the second wiring layer side of the multilayer wiring board, it becomes easy to take heat radiation measures of the first transistor and the second transistor, for example, a heat sink on the second wiring layer side of the multilayer wiring board.

Application Example 2

In the liquid ejecting apparatus according to the above-described application example, it is preferable that, when the multilayer wiring board is viewed in plan view, at least a part of the first transistor, at least a part of the second transistor, and at least a part of the capacitor are arranged on the same line.

According to this application example, since at least a part of the first transistor, at least a part of the second transistor, and at least a part of the capacitor are arranged on the same line, it is possible to decrease the area of the electrical loop including the first transistor, the second transistor, and the capacitor. Accordingly, since it is possible to decrease parasitic inductance, it is possible to suppress ringing of the output voltage of the switching circuit. Therefore, it is possible to implement a liquid ejecting apparatus which can eject a liquid with high precision.

Application Example 3

In the liquid ejecting apparatus according to the above-described application example, it is preferable that the second wiring and the fifth wiring are formed at positions at least partially overlapping each other when the multilayer wiring board is viewed in plan view.

Usually, reverse currents flow in the second wiring and the fifth wiring. According to this application example, since the second wiring and the fifth wiring are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit. Therefore, it is possible to implement a liquid ejecting apparatus which can eject a liquid with high precision.

Application Example 4

In the liquid ejecting apparatus according to the above-described application example, it is preferable that the multilayer wiring board further has a sixth wiring formed in a wiring layer other than the first wiring layer, and a third via conductor electrically connecting the second wiring and the sixth wiring.

According to this application example, since the sixth wiring electrically connected to the second wiring is formed in a wiring layer (for example, the second wiring layer) other than the first wiring layer, the sixth wiring functions as a heat sink. Therefore, it is possible to improve heat radiation efficiency of the second transistor.

Application Example 5

In the liquid ejecting apparatus according to the above-described application example, it is preferable that the multilayer wiring board further has a seventh wiring formed in the first wiring layer, an eighth wiring formed in the second wiring layer, and a fourth via conductor electrically connecting the second wiring and the eighth wiring, the gate electrode of the first transistor is electrically connected to the seventh wiring, and the seventh wiring and the eighth wiring are formed at positions at least partially overlapping each other when the multilayer wiring board is viewed in plan view.

Usually, reverse currents flow in the seventh wiring and the eighth wiring. According to this application example, since the seventh wiring and the eighth wiring are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit. Therefore, it is possible to implement a liquid ejecting apparatus which can eject a liquid with high precision.

Application Example 6

In the liquid ejecting apparatus according to the above-described application example, it is preferable that the multilayer wiring board has a ninth wiring formed in the first wiring layer, a tenth wiring formed in the second wiring layer, and a fifth via conductor electrically connecting the third wiring and the tenth wiring, the gate electrode of the second transistor is electrically connected to the ninth wiring, and the ninth wiring and the tenth wiring are formed at positions at least partially overlapping each other when the multilayer wiring board is viewed in plan view.

Usually, reverse currents flow in the ninth wiring and the tenth wiring. According to this application example, since the ninth wiring and the tenth wiring are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit. Therefore, it is possible to implement a liquid ejecting apparatus which can eject a liquid with high precision.

Application Example 7

This application example is directed to a printing apparatus including any of the above-described liquid ejecting apparatuses.

According to this application example, since a liquid ejecting apparatus capable of ejecting a liquid with high precision is provided, it is possible to implement a printing apparatus having excellent printing quality.

Application Example 8

This application example is directed to a switching circuit including a multilayer wiring board having a first wiring layer and a second wiring layer, and a first transistor, a second transistor, and a capacitor mounted on the first wiring layer side of the multilayer wiring board, in which the multilayer wiring board has a first wiring, a second wiring, a third wiring, and a fourth wiring formed in the first wiring layer, a fifth wiring formed in the second wiring layer, a first via conductor electrically connecting the third wiring and the fifth wiring, and a second via conductor electrically connecting the fourth wiring and the fifth wiring, the drain electrode of the first transistor is electrically connected to the first wiring, the source electrode of the first transistor is electrically connected to the second wiring, the drain electrode of the second transistor is electrically connected to the second wiring, the source electrode of the second transistor is electrically connected to the third wiring, the first electrode of the capacitor is electrically connected to the first wiring, and the second electrode of the capacitor is electrically connected to the fourth wiring.

According to this application example, the first transistor, the second transistor, and the capacitor are all mounted on the first wiring layer side of the multilayer wiring board, and form an electrical loop through the fifth wiring formed in the second wiring layer. Accordingly, even if the capacitor increases, it is possible to suppress an increase in the area of the electrical loop including the first transistor, the second transistor, and the capacitor compared to a case where the capacitor is mounted on the second wiring layer side of the multilayer wiring board. It is also possible to suppress an increase in the area of the electrical loop including the first transistor, the second transistor, and the capacitor compared to a case where all wirings are formed in the same wiring layer. That is, it is possible to suppress an increase in parasitic inductance. Therefore, it is possible to suppress ringing of the output voltage of the switching circuit.

Since the first transistor, the second transistor, and the capacitor are all mounted on the first wiring layer side of the multilayer wiring board, it is possible to easily perform mounting.

Since there are no elements arranged on the second wiring layer side of the multilayer wiring board, it becomes easy to take heat radiation measures of the first transistor and the second transistor, for example, a heat sink on the second wiring layer side of the multilayer wiring board.

Application Example 9

In the switching circuit according to the above-described application example, it is preferable that, when the multilayer wiring board is viewed in plan view, at least a part of the first transistor, at least a part of the second transistor, and at least a part of the capacitor are arranged on the same line.

According to this application example, since at least a part of the first transistor, at least a part of the second transistor, and at least a part of the capacitor are arranged on the same line, it is possible to decrease the area of the electrical loop including the first transistor, the second transistor, and the capacitor. Accordingly, since it is possible to decrease parasitic inductance, it is possible to suppress ringing of the output voltage of the switching circuit.

Application Example 10

In the switching circuit according to the above-described application example, it is preferable that the second wiring and the fifth wiring are formed at positions at least partially overlapping each other when the multilayer wiring board is viewed in plan view.

Usually, reverse currents flow in the second wiring and the fifth wiring. According to this application example, since the second wiring and the fifth wiring are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit.

Application Example 11

In the switching circuit according to the above-described application example, it is preferable that the multilayer wiring board further has a sixth wiring formed in a wiring layer other than the first wiring layer, and a third via conductor electrically connecting the first wiring and the sixth wiring.

According to this application example, since the sixth wiring electrically connected to the first wiring is formed in a wiring layer (for example, the second wiring layer) other than the first wiring layer, the sixth wiring functions as a heat sink. Accordingly, it is possible to improve heat radiation efficiency of the first transistor.

Application Example 12

In the switching circuit according to the above-described application example, it is preferable that the multilayer wiring board further has a seventh wiring formed in a wiring layer other than the first wiring layer, and a fourth via conductor electrically connecting the second wiring and the seventh wiring.

According to this application example, since the seventh wiring electrically connected to the second wiring is formed in a wiring layer (for example, the second wiring layer) other than the first wiring layer, the seventh wiring functions as a heat sink. Accordingly, it is possible to improve heat radiation efficiency of the second transistor.

Application Example 13

In the switching circuit according to the above-described application example, it is preferable that the multilayer wiring board further has an eighth wiring formed in the first wiring layer, a ninth wiring formed in the second wiring layer, and a fifth via conductor electrically connecting the second wiring and the ninth wiring, the gate electrode of the first transistor is electrically connected to the eighth wiring, and the eighth wiring and the ninth wiring are formed at positions at least partially overlapping each other when the multilayer wiring board is viewed in plan view.

Usually, reverse currents flow in the eighth wiring and the ninth wiring. According to this application example, since the eighth wiring and the ninth wiring are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit.

Application Example 14

In the switching circuit according to the above-described application example, it is preferable that the multilayer wiring board further has a tenth wiring formed in the first wiring layer, the gate electrode of the second transistor is electrically connected to the tenth wiring, and the fifth wiring and the tenth wiring are formed at positions at least partially overlapping each other when the multilayer wiring board is viewed in plan view.

Usually, reverse currents flow in the fifth wiring and the tenth wiring. According to this application example, since the fifth wiring and the tenth wiring are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit.

Application Example 15

This application example is directed to a medical instrument including a capacitive load drive circuit, in which the capacitive load drive circuit includes a drive waveform generator which generates a drive waveform signal, a modulator which performs pulse modulation on the drive waveform signal to generate a modulated signal, the above-described switching circuit which receives the modulated signal on the gate electrode of the first transistor and the gate electrode of the second transistor, and generates an amplified digital signal as a signal obtained through power amplification on the modulated signal, and a low pass filter which smoothes the amplified digital signal to generate a drive signal.

According to this application example, since a switching circuit in which the occurrence of ringing is suppressed is provided, it is possible to implement a medical instrument which can stably handle a fluid.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a preferred embodiment of the invention will be described in detail referring to the drawings. The drawings to be used are for convenience of description. The following embodiment is not intended to unduly limit the content of the invention described in the appended claims. It is not always true that the entire configuration described below is the essential constituent requirement of the invention.

Hereinafter, an embodiment of the invention will be described in the following sequence.

1. Configuration example of printing apparatus and liquid ejecting apparatus

2. Circuit configuration of capacitive load drive circuit

3. Arrangement example of switching circuit

4. First modification of arrangement example of switching circuit

5. Second modification of arrangement example of switching circuit

6. Third modification of arrangement example of switching circuit

7. Fourth modification of arrangement example of switching circuit

8. Fifth modification of arrangement example of switching circuit

9. Medical instrument

1. Configuration Example of Printing Apparatus and Liquid Ejecting Apparatus

FIG. 1is an explanatory view showing a configuration example of an ink jet printer10as an example of a printing apparatus. The ink jet printer10includes a carriage23which forms ink dots on a printing medium3while reciprocating in a main scanning direction, a drive mechanism33which reciprocates the carriage23, a platen roller36which feeds the printing medium3, and the like. The carriage23is provided with an ink cartridge16which stores ink, a carriage case22in which the ink cartridge16is mounted, an ejecting head24which is mounted on the bottom side (the side facing the printing medium3) of the carriage case22and ejects ink, and the like. Ink in the ink cartridge16is guided to the ejecting head24and ejected from the ejecting head24onto the printing medium3to print an image.

The drive mechanism33which reciprocates the carriage23includes a timing belt35which is stretched by pulleys, a stepping motor34which drives the timing belt35through the pulleys, and the like. A part of the timing belt35is fixed to the carriage case22, and the timing belt35is driven to reciprocate the carriage case22. The platen roller36constitutes a sheet feed mechanism, which feeds the printing medium3, along with a drive motor or a gear mechanism (not shown), and can feed the printing medium3by a predetermined amount in a sub-scanning direction.

In the ink jet printer10, a printer control circuit50which controls the entire operation, and a capacitive load drive circuit200which drives the ejecting head24are mounted. The printer control circuit50controls the entire operation in which the capacitive load drive circuit200, the drive mechanism33, the sheet feed mechanism, and the like drive the ejecting head24to eject ink while feeding the printing medium3.

FIG. 2is an explanatory view showing a configuration example of a liquid ejecting apparatus100in the ink jet printer10.FIG. 2shows an aspect in which the capacitive load drive circuit200drives the ejecting head24under the control of the printer control circuit50. First, the internal structure of the ejecting head24will be simply described. As shown in the drawing, a plurality of ejecting ports101through which ink droplets are ejected are provided at the bottom of the ejecting head24facing the printing medium3. Each ejecting port101is connected to an ink chamber102, and ink supplied from the ink cartridge16is filled in the ink chamber102. A piezoelectric element104is provided above each ink chamber102. If a voltage is applied to the piezoelectric element104, the piezoelectric element104is deformed to pressurize the ink chamber102, and ink is ejected from the ejecting port101. The piezoelectric element104changes in deformation amount depending on a voltage value to be applied. An appropriate voltage waveform is applied to the piezoelectric element104to control the deformation amount or timing of the ink chamber102, whereby an appropriate amount of ink can be ejected at an appropriate timing.

A drive signal408which is a voltage to be applied to the piezoelectric element104is generated on the basis of a control signal400from the printer control circuit50by the capacitive load drive circuit200. The generated drive signal408is supplied to the piezoelectric element104through a gate unit300. The gate unit300is a circuit unit in which a plurality of gate elements302are connected in parallel, and each gate element302can be individually placed in a conduction state or a disconnection state under the control of the printer control circuit50. Accordingly, the drive signal408output from the capacitive load drive circuit200passes through the gate element302set in the conduction state in advance by the printer control circuit50and applied to the corresponding piezoelectric element104, and ink is ejected from the ejecting port101.

2. Circuit Configuration of Capacitive Load Drive Circuit

FIG. 3is an explanatory view showing the detailed configuration of the capacitive load drive circuit200of this embodiment. As shown in the drawing, capacitive load drive circuit200includes a drive waveform generator210which generates a drive waveform signal402, a modulator220which performs pulse modulation on the drive waveform signal402to generate a modulated signal GH and a modulated signal GL, a switching circuit230which receives the modulated signal GH and the modulated signal GL, and generates an amplified digital signal406which is a signal by performing power amplification on the modulated signal GH and the modulated signal GL, and a low pass filter240which smoothes the amplified digital signal406to generate the drive signal408. A capacitive load Z1to which the drive signal408is applied corresponds to the piezoelectric element104shown inFIG. 2.

The drive waveform generator210generates a drive waveform signal402as a reference of the drive signal408on the basis of the control signal400.

The modulator220includes a PWM modulator221which performs PWM modulation (pulse-width modulation) on the drive waveform signal402to generate a PWM modulated signal404, and a gate driver circuit222which generates the modulated signal GH and the modulated signal GL on the basis of the PWM modulated signal404.

The gate driver circuit222includes a level shifter224which adjusts the level of the PWM modulated signal404, a high-side driver228H which switches the ON/OFF of a first transistor M1on the basis of the PWM modulated signal404through the level shifter224, and a low-side driver228L which switches the ON/OFF of a second transistor M2on the basis of the PWM modulated signal404through the level shifter224.

A signal which is output from the high-side driver228H when switching the ON/OFF of the first transistor M1is defined as the modulated signal GH, and a signal which is output from the low-side driver228L when switching the ON/OFF of the second transistor M2is defined as the modulated signal GL.

The switching circuit230is constituted as a digital power amplifier including the first transistor M1and the second transistor M2which generate the amplified digital signal406, and a capacitor C1which functions as a bypass capacitor. In the capacitive load drive circuit200of this embodiment, although the first transistor M1and the second transistor M2are N-type MOSFETs, for example, other kinds of elements, such as an insulated gate bipolar transistor (IGBT), may be used. As a switching circuit to which the invention is applied, there are various switching circuits including a switching amplifier circuit, a switching power supply circuit, a motor drive circuit, and an inverter circuit.

As shown inFIG. 3, the first transistor M1and the second transistor M2are connected between a potential VDD (hereinafter, simply referred to as VDD) to be supplied from the power supply and a ground potential GND (hereinafter, simply referred to as GND). The amplified digital signal406is generated by switching the ON/OFF of the first transistor M1and the second transistor M2. A contact (node) at which the first transistor M1and the second transistor M2are connected is defined as a first node N1. The first node N1is on a wiring through which the amplified digital signal406is transmitted. The capacitor C1is connected between VDD and GND.

The low pass filter240removes a high-frequency component of the amplified digital signal406to generate the drive signal408. In the example shown inFIG. 3, the low pass filter240is constituted as a low pass filter including a coil LF and a capacitor CF.

FIG. 4is an explanatory view showing the outline of an operation of the capacitive load drive circuit200to generate the drive signal408. For example, the drive waveform generator210generates the drive waveform signal402shown inFIG. 4on the basis of the control signal400. The drive waveform signal402is not limited to an analog signal shown inFIG. 4, and for example, a signal output at DC level or a multibit digital signal may be used.

The drive waveform generator210may include, for example, an arithmetic unit and may compute the drive waveform signal402on the basis of the control signal400. The drive waveform generator210may include, for example, a waveform memory which stores a waveform, and may generate the drive waveform signal402corresponding to the control signal400with reference to the waveform memory.

If the drive waveform signal402from the drive waveform generator210is received, the modulator220performs predetermined modulation to generate the modulated signal GH and the modulated signal GL. In this embodiment, although the predetermined modulation is pulse-width modulation (PWM), for example, other modulation systems, such as pulse-density modulation (PDM), may be used.

The switching circuit230receives the modulated signal GH and the modulated signal GL, and performs power amplification. As shown inFIG. 3, the switching circuit230amplifies power using the first transistor M1and the second transistor M2. In the example shown inFIG. 4, the switching circuit230generates the amplified digital signal406in which the voltage of the PWM modulated signal404is amplified to VDD.

The low pass filter240smoothes the amplified digital signal406to generate the analog drive signal408in which a portion modulated to a wide pulse width has a high voltage value, and a portion modulated to a narrow pulse width has a low voltage value. As shown inFIG. 3, the low pass filter240can be easily implemented by combining the coil LF and the capacitor CF.

In the capacitive load drive circuit200of this embodiment, since the switching circuit230switches the ON/OFF of the first transistor M1and the second transistor M2to amplify power, there is no case where extra power is consumed. The low pass filter240may be constituted by components, such as the coil LF and the capacitor CF, which do not consume power. For this reason, since it is possible to significantly reduce power loss compared to a case where, like a so-called analog amplifier circuit, power amplification is performed on the analog drive waveform signal402in an analog form, it is possible to significantly reduce power loss when generating the drive signal408.

In the switching circuit230, ringing of the output voltage may become problematic. If ringing occurs, since EMI noise occurs, there is an interference with the operation of the apparatus itself or peripherals. When the rising time of the switching waveform is extended so as to suppress ringing, power efficiency is degraded, and fluid control precision is degraded. If ringing occurs, a voltage which is applied to the first transistor M1and the second transistor M2increases, causing element breakdown or erroneous operation.

As the factor for the occurrence of ringing, there is a resonance phenomenon by parasitic inductance of the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1and parasitic capacitance between the drain and source of the first transistor M1or the second transistor M2, a resonance phenomenon by parasitic inductance of the electrical loop including the high-side driver228H and the first transistor M1and gate capacitance of the first transistor M1, a resonance phenomenon by parasitic inductance of the electrical loop including the low-side driver228L and the second transistor M2and gate capacitance of the second transistor M2, or the like.

Accordingly, when arranging elements constituting the switching circuit230or wirings, in particular, it is important to decrease parasitic inductance of the electrical loop.

3. Arrangement Example of Switching Circuit

The switching circuit230of this embodiment includes a multilayer wiring board1000having a first wiring layer and a second wiring layer, and the first transistor M1, the second transistor M2, and the capacitor C1mounted on the first wiring layer side of the multilayer wiring board1000.

FIGS. 5A and 5Bare plan views showing an arrangement example of the switching circuit230.FIG. 5Aprimarily shows the configuration of the first wiring layer.FIG. 5Bprimarily shows the configuration of the second wiring layer. InFIGS. 5A and 5B, a solid polygon represents a wiring formed in the first wiring layer or the second wiring layer, and a solid circle represents the position of a via conductor which electrically connects a wiring of the first wiring layer and a wiring of the second wiring layer. InFIG. 5A, a one-dot-chain line represents the mounting position of each transistor, the capacitor, or the coil, and a dotted line represents the position of an electrode of each transistor, the capacitor, or the coil.

FIG. 6is a sectional view taken along the line A-A ofFIGS. 5A and 5B. As shown inFIG. 6, an insulating layer is provided between the first wiring layer and the second wiring layer of the multilayer wiring board1000. That is, a wiring formed in the first wiring layer and a wiring formed in the second wiring layer are insulated from each other, except for connection by a via conductor. Usually, the thickness of the insulating layer is sufficiently smaller than the wiring width. The multilayer wiring board1000has three or more wiring layers, and two wiring layers arbitrarily selected from among the three or more wiring layers may be the first wiring layer and the second wiring layer. It is preferable that the first wiring layer and the second wiring layer are wiring layers closest to each other. The multilayer wiring board1000may have a protective layer which protects a wiring layer.

The multilayer wiring board1000of this embodiment has a first wiring1001, a second wiring1002, a third wiring1003, and a fourth wiring1004formed in the first wiring layer, a fifth wiring1005formed in the second wiring layer, a first via conductor2001which electrically connects the third wiring1003and the fifth wiring1005, and a second via conductor2002which electrically connects the fourth wiring1004and the fifth wiring1005.

A drain electrode D of the first transistor M1is electrically connected to the first wiring1001, and a source electrode S of the first transistor M1is electrically connected to the second wiring1002. A drain electrode D of the second transistor M2is electrically connected to the second wiring1002, and a source electrode S of the second transistor M2is electrically connected to the third wiring1003. A first electrode +C1of the capacitor C1is electrically connected to the first wiring1001, and a second electrode −C1of the capacitor C1is electrically connected to the fourth wiring1004. That is, a part of a wiring path from the source electrode S of the second transistor M2to the second electrode −C1of the capacitor C1is formed as the fifth wiring1005of the second wiring layer.

According to this embodiment, since the first transistor M1, the second transistor M2, and the capacitor C1are all mounted on the first wiring layer side of the multilayer wiring board1000, and electrically form a loop through the fifth wiring1005formed in the second wiring layer, the area of the electrical loop significantly depends on the inter-layer distance between the first wiring layer and the second wiring layer, that is, the thickness of the insulating layer. Accordingly, even if the capacitor C1increases, it is possible to suppress an increase in the area of the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1compared to a case where the capacitor C1is mounted on the second wiring layer side of the multilayer wiring board1000. Since the thickness of the insulating layer is sufficiently smaller than the wiring width, it is possible to suppress an increase in the area of the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1compared to a case where all wirings are formed in the same wiring layer. That is, it is possible to suppress an increase in parasitic inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

Since the first transistor M1, the second transistor M2, and the capacitor C1are all mounted on the first wiring layer side of the multilayer wiring board1000, it is possible to easily perform mounting.

Since the elements are not arranged on the second wiring layer side of the multilayer wiring board1000, it becomes easy to take heat radiation measures of the first transistor M1and the second transistor M2, for example, a heat sink on the second wiring layer side of the multilayer wiring board1000.

In the example shown inFIG. 5A, when the multilayer wiring board1000is viewed in plan view, at least a part of the first transistor M1, at least a part of the second transistor M2, and at least a part of the capacitor C1are arranged on the same line. In the example shown inFIGS. 5A and 6, the capacitor C1, the first transistor M1, and the second transistor M2are arranged on the same line in this order.

According to this embodiment, since at least a part of the first transistor M1, at least a part of the second transistor M2, and at least a part of the capacitor C1are arranged on the same line, it is possible to decrease the area of the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1. Accordingly, since it is possible to decrease parasitic inductance, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 5A and 5B, the second wiring1002and the fifth wiring1005are formed at position at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

FIG. 7is a diagram illustrating parasitic inductance.FIG. 7shows two wirings which are provided to be separated from each other. If a current flows in one wiring, a counter electromotive force is generated in a direction of cancelling a magnetic field by the current. When two wirings are provided to be close to each other, a counter electromotive force is generated in the other wiring in a direction of cancelling a magnetic field by a current flowing in one wiring (the effect of mutual inductance). Accordingly, it is possible to reduce parasitic inductance of wiring by providing wiring such that currents flowing in two wirings are reverse currents.

Usually, reverse currents flow in the second wiring1002and the fifth wiring1005. According to this embodiment, since the second wiring1002and the fifth wiring1005are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance described referring toFIG. 7. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 5A and 5B, the multilayer wiring board1000further has a sixth wiring1006formed in the second wiring layer as a wiring layer other than the first wiring layer, and a third via conductor2003which electrically connects the first wiring1001and the sixth wiring1006.

According to this embodiment, since the sixth wiring1006electrically connected to the first wiring1001is formed in a wiring layer (for example, the second wiring layer) other than the first wiring layer, the sixth wiring1006functions as a heat sink. Accordingly, it is possible to improve heat radiation efficiency of the first transistor M1.

In the example shown inFIGS. 5A and 5B, the multilayer wiring board1000further has a seventh wiring1007formed in a wiring layer other than the first wiring layer, and a fourth via conductor2004which electrically connects the second wiring1002and the seventh wiring1007.

According to this embodiment, since the seventh wiring1007electrically connected to the second wiring1002is formed in a wiring layer (for example, the second wiring layer) other than the first wiring layer, the seventh wiring1007functions as a heat sink. Accordingly, it is possible to improve heat radiation efficiency of the second transistor M2.

In the example shown inFIGS. 5A and 5B, multilayer wiring board1000further has an eighth wiring1008formed in the first wiring layer, a ninth wiring1009formed in the second wiring layer, and a fifth via conductor2005which electrically connects the second wiring1002and the ninth wiring1009, a gate electrode G of the first transistor M1is electrically connected to the eighth wiring1008, and the eighth wiring1008and the ninth wiring1009are formed at positions at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

Usually, reverse currents flow in the eighth wiring1008and the ninth wiring1009. According to this embodiment, since the eighth wiring1008and the ninth wiring1009are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance described referring toFIG. 7. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 5A and 5B, the multilayer wiring board1000further has a tenth wiring1010formed in the first wiring layer, a gate electrode G of the second transistor M2is electrically connected to the tenth wiring1010, and the fifth wiring1005and the tenth wiring1010are formed at positions at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

Usually, reverse currents flow in the fifth wiring1005and the tenth wiring1010. According to this embodiment, since the fifth wiring1005and the tenth wiring1010are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance described referring toFIG. 7. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 5A and 5B, the multilayer wiring board1000further has an eleventh wiring1011which is formed in the first wiring layer and electrically connected to a first electrode +CF (a positive potential-side electrode) of the capacitor CF, and the fifth wiring1005and the eleventh wiring1011are formed at positions at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

When common mode noise lies on the output signal of the capacitive load drive circuit200, a component of common mode noise appears as a current component in the same direction in the fifth wiring1005and the eleventh wiring1011. According to this embodiment, since the fifth wiring1005and the eleventh wiring1011are formed at positions at least partially overlapping each other, the effect of mutual inductance described referring toFIG. 7acts in a direction of cancelling common mode noise. Accordingly, it is possible to suppress common mode noise. It is also possible to suppress EMI noise due to common mode noise.

FIG. 8Ais a graph showing an output voltage waveform example of the switching circuit230of this embodiment, andFIG. 8Bis a graph showing an output voltage waveform example of a switching circuit of a comparative example. The switching circuit of the comparative example is a circuit in which all wirings constituting the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1are formed in the first wiring layer, and electrical connection is the same as the circuit diagram shown inFIG. 3. An output voltage waveform is a voltage waveform which is measured on a node corresponding to the first node N1.

In the output voltage waveform example of the comparative example shown inFIG. 8B, ringing occurs at the time of the rising and falling of the voltage waveform. In the output voltage waveform example of this embodiment shown inFIG. 8A, the occurrence of ringing is reduced by various actions described above.

As in this embodiment, when the liquid ejecting apparatus100which can eject a liquid with high precision is applied to a printing apparatus (ink jet printer10), it is possible to implement a printing apparatus having excellent printing quality.

4. First Modification of Arrangement Example of Switching Circuit

The same parts as the foregoing embodiment are represented by the same reference numerals, and detailed description thereof will not be repeated.

FIG. 9is an explanatory view showing the detailed configuration of a capacitive load drive circuit200of a first modification. When comparing with the example shown inFIG. 3, in the example shown inFIG. 9, there is a difference in that a capacitor C2is further provided in parallel to the capacitor C1, and other parts are the same as those of the capacitive load drive circuit200shown inFIG. 3. The configuration shown inFIG. 9is advantageous compared to the configuration shown inFIG. 3in that the capacitance of the bypass capacitor can increase.

FIGS. 10A and 10Bare plan views showing a first modification of the arrangement example of the switching circuit230.FIG. 10Aprimarily shows the configuration of the first wiring layer.FIG. 10Bprimarily shows the configuration of the second wiring layer. InFIGS. 10A and 10B, a solid polygon represents a wiring formed in the first wiring layer or the second wiring layer, and a solid circle represents the position of a via conductor which electrically connects a wiring of the first wiring layer and a wiring of the second wiring layer. InFIG. 10A, a one-dot-chain line represents the mounting position of each transistor, the capacitor, or the coil, and a dotted line represents the position of an electrode of each transistor, the capacitor, or the coil.

In the example shown inFIG. 10A, a first electrode +C2of the capacitor C2is electrically connected to the first wiring1001, and a second electrode −C2of the capacitor C2is electrically connected to the third wiring1003. Other parts are the same as those in the example shown inFIGS. 5A and 5B.

In this configuration, the same effects are also obtained by the same reasons as in the foregoing embodiment.

5. Second Modification of Arrangement Example of Switching Circuit

The same parts as those in the foregoing embodiment and the first modification are represented by the same reference numerals, and detailed description thereof will not be repeated. The circuit configuration of a capacitive load drive circuit200in a second modification is the configuration shown inFIG. 9.

FIGS. 11A and 11Bare plan views showing a second modification of the arrangement example of the switching circuit230.FIG. 11Aprimarily shows the configuration of the first wiring layer.FIG. 11Bprimarily shows the configuration of the second wiring layer. InFIGS. 11A and 11B, a solid polygon represents a wiring formed in the first wiring layer or the second wiring layer, and a solid circle represents the position of a via conductor which electrically connects a wiring of the first wiring layer and a wiring of the second wiring layer. InFIG. 11A, a one-dot-chain line represents the mounting position of each transistor, the capacitor, or the coil, and a dotted line represents the position of an electrode of each transistor, the capacitor, or the coil.

When comparing the first modification and the second modification, the arrangement of each electrode of the first transistor M1and the second transistor M2is different, and other parts are the same.

In this configuration, the same effects are also obtained by the same reasons as in the foregoing embodiment.

6. Third Modification of Arrangement Example of Switching Circuit

A switching circuit230in a third modification includes a multilayer wiring board1000having a first wiring layer and a second wiring layer, and a first transistor M1, a second transistor M2, and a capacitor C1which are mounted on the first wiring layer side of the multilayer wiring board1000. The circuit configuration of a capacitive load drive circuit200in the third modification is the configuration shown inFIG. 3.

FIGS. 12A and 12Bare plan views showing a third modification of the arrangement example of the switching circuit230.FIG. 12Aprimarily shows the configuration of the first wiring layer.FIG. 12Bprimarily shows the configuration of the second wiring layer. InFIGS. 12A and 12B, a solid polygon represents a wiring formed in the first wiring layer or the second wiring layer, and a solid circle represents the position of a via conductor which electrically connects a wiring of the first wiring layer and a wiring of the second wiring layer. InFIG. 12A, a one-dot-chain line represents the mounting position of each transistor, the capacitor, or the coil, and a dotted line represents the position of an electrode of each transistor, the capacitor, or the coil.

FIG. 13is a sectional view taken along the line A-A ofFIGS. 12A and 12B. As shown inFIG. 13, an insulating layer is provided between the first wiring layer and the second wiring layer of the multilayer wiring board1000. That is, a wiring formed in the first wiring layer and a wiring formed in the second wiring layer are insulated from each other, except for connection by a via conductor. Usually, the thickness of the insulating layer is sufficiently smaller than the wiring width. The multilayer wiring board1000may have three or more wiring layers, and two wiring layers arbitrarily selected from among the three or more wiring layers may be the first wiring layer and the second wiring layer. It is preferable that the first wiring layer and the second wiring layer are wiring layers closest to each other. The multilayer wiring board1000may have a protective layer which protects a wiring layer.

The multilayer wiring board1000in the third modification has a first wiring3001, a second wiring3002, a third wiring3003, and a fourth wiring3004formed in the first wiring layer, a fifth wiring3005formed in the second wiring layer, a first via conductor4001which electrically connects the first wiring3001and the fifth wiring3005, and a second via conductor4002which electrically connects the fourth wiring3004and the fifth wiring3005.

A drain electrode D of the first transistor M1is electrically connected to the first wiring3001, and a source electrode S of the first transistor M1is electrically connected to the second wiring3002. A drain electrode D of the second transistor M2is electrically connected to the second wiring3002, and a source electrode S of the second transistor M2is electrically connected to the third wiring3003. A first electrode +C1of the capacitor C1is electrically connected to the fourth wiring3004, and a second electrode −C1of the capacitor C1is electrically connected to the third wiring3003. That is, a part of a wiring path from the drain electrode D of the first transistor M1to the first electrode +C1of the capacitor C1is formed as the fifth wiring3005of the second wiring layer.

According to the third modification, since the first transistor M1, the second transistor M2, and the capacitor C1are all mounted on the first wiring layer side of the multilayer wiring board1000, and form an electrical loop through the fifth wiring3005formed in the second wiring layer, the area of the electrical loop significantly depends on the inter-layer distance between the first wiring layer and the second wiring layer, that is, the thickness of the insulating layer. Accordingly, even if the capacitor C1increases, it is possible to suppress an increase in the area of the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1compared to a case where the capacitor C1is mounted on the second wiring layer side of the multilayer wiring board1000. Since the thickness of the insulating layer is sufficiently smaller than the wiring width, it is possible to suppress an increase in the area of the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1compared to a case where all wirings are formed in the same wiring layer. That is, it is possible to suppress an increase in parasitic inductance. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

Since the first transistor M1, the second transistor M2, and the capacitor C1are all mounted on the first wiring layer side of the multilayer wiring board1000, it is possible to easily perform mounting.

Since there are no elements arranged on the second wiring layer side of the multilayer wiring board1000, it becomes easy to take heat radiation measures of the first transistor M1and the second transistor M2, for example, a heat sink on the second wiring layer side of the multilayer wiring board1000.

In the example shown inFIG. 12A, when the multilayer wiring board1000is viewed in plan view, at least a part of the first transistor M1, at least a part of the second transistor M2, and at least a part of the capacitor C1are arranged on the same line. In the example shown inFIGS. 12A and 13, the first transistor M1, the second transistor M2, and the capacitor C1are arranged on the same line in this order.

According to the third modification, since at least a part of the first transistor M1, at least a part of the second transistor M2, and at least a part of the capacitor C1are arranged on the same line, it is possible to decrease the area of the electrical loop including the first transistor M1, the second transistor M2, and the capacitor C1. Accordingly, since it is possible to decrease parasitic inductance, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 12A and 12B, the second wiring3002and the fifth wiring3005are formed at positions at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

Usually, reverse currents flow in the second wiring3002and the fifth wiring3005. According to the third modification, since the second wiring3002and the fifth wiring3005are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance described referring toFIG. 7. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 12A and 12B, the multilayer wiring board1000further has a sixth wiring3006formed in a wiring layer other than the first wiring layer, and a third via conductor4003which electrically connects the second wiring3002and the sixth wiring3006.

According to the third modification, since the sixth wiring3006electrically connected to the second wiring3002is formed in a wiring layer (for example, the second wiring layer) other than the first wiring layer, the sixth wiring3006functions as a heat sink. Accordingly, it is possible to improve heat radiation efficiency of the second transistor M2.

In the example shown inFIGS. 12A and 12B, the multilayer wiring board1000further has a seventh wiring3007formed in the first wiring layer, an eighth wiring3008formed in the second wiring layer, and a fourth via conductor4004which electrically connects the second wiring3002and the eighth wiring3008, a gate electrode G of the first transistor M1is electrically connected to the seventh wiring3007, and the seventh wiring3007and the eighth wiring3008are formed at positions at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

Usually, reverse currents flow in the seventh wiring3007and the eighth wiring3008. According to the third modification, since the seventh wiring3007and the eighth wiring3008are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance described referring toFIG. 7. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 12A and 12B, the multilayer wiring board1000further has a ninth wiring3009formed in the first wiring layer, a tenth wiring3010formed in the second wiring layer, and a fifth via conductor4005which electrically connects the third wiring3003and the tenth wiring3010, a gate electrode G of the second transistor M2is electrically connected to the ninth wiring3009, and the ninth wiring3009and the tenth wiring3010are formed at positions at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

Usually, reverse currents flow in the ninth wiring3009and the tenth wiring3010. According to the third modification, since the ninth wiring3009and the tenth wiring3010are formed at positions at least partially overlapping each other, parasitic inductance decreases by the effect of mutual inductance described referring toFIG. 7. Accordingly, it is possible to suppress ringing of the output voltage of the switching circuit230. Therefore, it is possible to implement the liquid ejecting apparatus100which can eject a liquid with high precision.

In the example shown inFIGS. 12A and 12B, the multilayer wiring board1000further has an eleventh wiring3011which is formed in the first wiring layer and electrically connected to the first electrode +CF (the positive potential-side electrode) of the capacitor CF, a twelfth wiring3012formed in the second wiring layer, and a sixth via conductor4006which electrically connects the third wiring3003and the twelfth wiring3012, and the eleventh wiring3011and the twelfth wiring3012are formed at positions at least partially overlapping each other when the multilayer wiring board1000is viewed in plan view.

When common mode noise lies on the output signal of the capacitive load drive circuit200, a component of common mode noise appears as a current component in the same direction in the eleventh wiring3011and the twelfth wiring3012. According to the third modification, since the eleventh wiring3011and the twelfth wiring3012are formed at positions at least partially overlapping each other, the effect of mutual inductance described referring toFIG. 7acts in a direction of cancelling common mode noise. Accordingly, it is possible to suppress common mode noise. It is also possible to suppress EMI noise due to common mode noise.

In this way, in the third modification, as in the output voltage waveform example shown inFIG. 8A, the occurrence of ringing is reduced by various actions described above.

As in the third modification, when the liquid ejecting apparatus100which can eject a liquid with high precision is applied to a printing apparatus (ink jet printer10), it is possible to implement a printing apparatus having excellent printing quality.

7. Fourth Modification of Arrangement Example of Switching Circuit

The same parts as those in the foregoing third modification are represented by the same reference numerals, and detailed description thereof will not be repeated. The circuit configuration of the capacitive load drive circuit200in the fourth modification is the configuration shown inFIG. 9.

FIGS. 14A and 14Bare plan views showing a fourth modification of the arrangement example of the switching circuit230.FIG. 14Aprimarily shows the configuration of the first wiring layer.FIG. 14Bprimarily shows the configuration of the second wiring layer. InFIGS. 14A and 14B, a solid polygon represents a wiring formed in the first wiring layer or the second wiring layer, and a solid circle represents the position of a via conductor which electrically connects a wiring of the first wiring layer and a wiring of the second wiring layer. InFIG. 14A, a one-dot-chain line represents the mounting position of each transistor, the capacitor, or the coil, and a dotted line represents the position of an electrode of each transistor, the capacitor, or the coil.

In the example shown inFIG. 14A, a first electrode +C2of the capacitor C2is electrically connected to the first wiring3001, and a second electrode −C2of the capacitor C2is electrically connected to the third wiring3003. Other parts are the same as those in the third modification shown inFIGS. 12A and 12B.

In this configuration, the same effects are obtained by the same reasons as in the foregoing embodiment and the third modification.

8. Fifth Modification of Arrangement Example of Switching Circuit

The same parts as those in the foregoing third modification and fourth modification are represented by the same reference numerals, and detailed description thereof will not be repeated. The circuit configuration of the capacitive load drive circuit200in the fifth modification is the configuration shown inFIG. 9.

FIGS. 15A and 15Bare plan views showing a fifth modification of the arrangement example of the switching circuit230.FIG. 15Aprimarily shows the configuration of the first wiring layer.FIG. 15Bprimarily shows the configuration of the second wiring layer. InFIGS. 15A and 15B, a solid polygon represents a wiring formed in the first wiring layer or the second wiring layer, and a solid circle represents the position of a via conductor which electrically connects a wiring of the first wiring layer and a wiring of the second wiring layer. InFIG. 15A, a one-dot-chain line represents the mounting position of each transistor, the capacitor, or the coil, and a dotted line represents the position of an electrode of each transistor, the capacitor, or the coil.

When comparing the fourth modification and the fifth modification, the arrangement of each electrode of the first transistor M1and the second transistor M2is different, and other parts are the same.

In this configuration, the same effects are obtained by the same reasons as in the foregoing embodiment and the third modification.

9. Medical Instrument

The capacitive load drive circuit200using the switching circuit230is mounted in various medical instruments, thereby increasing reliability of the medical instruments. A fluid ejecting apparatus1and a fluid transport apparatus20described below are a configuration example included in a liquid ejecting apparatus.

For example, the capacitive load drive circuit200may be applied as a fluid ejecting apparatus1.FIG. 16is an explanatory view illustrating the fluid ejecting apparatus1. Although the fluid ejecting apparatus1is used in various ways for cleaning minute objects and structures and for scalpels, in this case, description will be provided as the fluid ejecting apparatus1suitable for operation or treatment of a biological tissue. Accordingly, the fluid is a liquid, for example, water, physiological saline solution, or the like.

InFIG. 16, the fluid ejecting apparatus1includes a fluid supply container2which stores a fluid, a pump14as a fluid supply unit, a pulsation generation unit21which converts the fluid supplied from the pump14to a pulsation (hereinafter, referred to as a pulse flow), and a drive control unit15which controls the driving of the pump14and the pulsation generation unit21. The pump14and the pulsation generation unit21are connected together by a fluid supply tube4.

A slender pipe-shaped connection flow path tube90is connected to the pulsation generation unit21, and a nozzle95which has a fluid ejection opening96with a reduced flow path diameter is inserted into the leading end of the connection flow path tube90. The connection flow path tube90has rigidity so as not to be deformed at the time of fluid ejection.

The pulsation generation unit21has an ejection command switching unit25, and in this embodiment, as the ejection command switching unit25, a pulse flow command switch26which is used to select pulse flow ejection, a continuous flow command switch27which is used to select continuous flow ejection, and an OFF switch28which is used to stop fluid ejection are provided.

The flow of the fluid in the fluid ejecting apparatus1configured as above will be simply described. The fluid stored in the fluid supply container2is sucked by the pump14and supplied to the pulsation generation unit21through the fluid supply tube4at a given pressure. The pulsation generation unit21is provided with a fluid chamber80(seeFIG. 17described below), and a piezoelectric element30and a diaphragm40as a volume change unit which changes the volume of the fluid chamber80. The piezoelectric element30is driven to generate a pulsation inside the fluid chamber80, and the fluid is ejected at high speed in a pulsed form from the fluid ejection opening96through the connection flow path tube90and the nozzle95.

When the driving of the pulsation generation unit21stops, the fluid supplied from the pump14is ejected in a continuous flow from the fluid ejection opening96through the fluid chamber80.

The pulsation means the flow of a fluid in which the flow direction of the fluid is kept constant and the flow rate or velocity of the fluid fluctuates periodically or irregularly. Although the pulsation includes an intermittent flow in which the fluid repeatedly flows and stops, the pulsation may not be a intermittent flow insofar as the flow rate or velocity of the fluid fluctuates periodically or irregularly.

Similarly, the pulsed ejection of the fluid means the ejection of the fluid in which the flow rate or velocity of the fluid to be ejected fluctuates periodically or irregularly. Although an example of the pulsed ejection includes intermittent ejection in which the ejection and non-ejection of the fluid are repeated, the pulsed ejection may not be intermittent ejection insofar as the flow rate or velocity of the fluid to be ejected fluctuates periodically or irregularly.

FIG. 17is a sectional view of the pulsation generation unit21of this embodiment taken along the ejection direction of the fluid. InFIG. 17, the scale of each member or portion is adjusted for convenience of illustration. The pulsation generation unit21has an entrance flow path81which supplies the fluid from the pump14to the fluid chamber80through the fluid supply tube4, a piezoelectric element30and a diaphragm40as a volume change unit which changes the volume of the fluid chamber80, and an exit flow path82which communicates with the liquid chamber80. The fluid supply tube4is connected to the entrance flow path81.

The diaphragm40is made of, for example a disk-like sheet metal, and comes into close contact with a case52by a case70. In regard to the piezoelectric element30, in this embodiment, a laminated piezoelectric element is illustrated, and one of both ends is fixed to the diaphragm40and the other end is fixed to a bottom plate60.

The fluid chamber80is a space which is formed by a concave portion formed in a surface of the case70facing the diaphragm40and the diaphragm40. The exit flow path82is formed substantially in the central portion of the fluid chamber80.

The case70and the case52are bonded together as a single body in opposing surfaces. A connection flow path tube90having a connection path91communicating with the exit flow path82is fitted into the case70, and the nozzle95is inserted into the leading end of the connection flow path tube90. The fluid ejection opening96with a reduced flow path diameter is formed in the nozzle95.

The piezoelectric element30corresponds to the capacitive load Z1ofFIG. 1, and the deformation amount or timing is controlled by the drive signal408(seeFIG. 16) of the capacitive load drive circuit200. The fluid chamber80is pressed in a direction of arrow A ofFIG. 17, whereby the fluid can be ejected in a pulsed form from the nozzle95at the leading end. The fluid ejecting apparatus1is used as, for example, a medical apparatus. Specifically, the fluid ejecting apparatus1may be used as a surgical apparatus which supplies a liquid at a high pressure from the pump14to the fluid supply tube4to be introduced into a body cavity and ejects the liquid from the nozzle95at the leading end to cut a tissue in the body cavity by a fluid pressure.

The capacitive load drive circuit200may be applied as the fluid transport apparatus20which transports the fluid at a stable flow rate.

FIG. 18is a perspective view showing the appearance of a fluid transporter1A including the fluid transport apparatus20of this embodiment. InFIG. 18, the fluid transporter1A includes the fluid transport apparatus20which transports the fluid by peristaltic motion, and a pack-shaped fluid storage container94which stores the fluid. The fluid transport apparatus20and the fluid storage container94communicate with each other by a tube4A.

The fluid storage container94is made of flexible synthetic resin, for example, silicon-based resin. A tube holder92is provided at one end of the fluid storage container94, and the tube4A is fixed airtight by crimping, thermal welding, or adhesion such that the fluid does not leak.

The tube4A communicates with the inside of the fluid storage container94at one end, passes through the fluid transport apparatus20, and extends outside the fluid transport apparatus20, and the fluid stored in the fluid storage container94is transported to the outside by the fluid transport apparatus20.

The fluid transport apparatus20has a structure in which a lower lid84, a pump unit frame31, a tube frame32, and an upper lid83are stacked sequentially and integrated by fixing screws97(in the drawing, upper lid fixing screws are shown) or the like. An extrusion mechanism which transports the fluid into is accommodated in the fluid transport apparatus20.

When the fluid transporter1A is put on a biological object, it is preferable that the lower lid84, the pump unit frame31, the tube frame32, the upper lid83, and the fluid storage container94are made of a material having excellent biocompatibility, for example, synthetic resin, such as polysulphone or urethane.

FIG. 19is a diagram illustrating a fluid transport mechanism of the fluid transport apparatus20. The drive signal408which is a voltage to be applied to the piezoelectric element104is generated on the basis of the control signal400from the extrusion control circuit50A (not shown inFIG. 18) by the capacitive load drive circuit200. The generated drive signal408is supplied to the piezoelectric element104through the gate unit300. The gate unit300is a circuit unit which a plurality of gate elements302are connected in parallel, and each gate element302can be individually placed in a conduction state or a disconnection state under the control of the extrusion control circuit50A. Accordingly, the drive signal408output from the capacitive load drive circuit200passes through the gate elements302in sequence by the extrusion control circuit50A and applied to the corresponding piezoelectric element104, and a corresponding pressing shaft106is extruded. The pressing shaft106is arranged perpendicular to the flow direction of the fluid in the tube4A. The tube4A is pressed in sequence by a plurality of pressing shafts106. For this reason, the fluid transport apparatus20can transport the fluid in the tube4A by peristaltic motion.

As a fluid which is used in the invention, in addition to liquids having fluidity, such as water, saline, chemicals, oils, fragrant liquids, and ink, gas may be used. For example, when chemical is used, the fluid transport apparatus20may be used as a medication pump.

In this way, according to the medical instrument of this embodiment, since the switching circuit230in which the occurrence of ringing is suppressed is provided, it is possible to implement a medical instrument which can stably handle a fluid.

The foregoing embodiments and modifications are just an example, and the invention is not limited thereto. For example, the embodiments and the modifications may be appropriately carried out in combination.

The invention is not limited to the foregoing embodiments and modifications, and may be modified in various ways. For example, the invention includes substantially the same configuration (for example, a configuration having the same functions, methods, and results, or a configuration having the same objects and effects) as the configuration described in the foregoing embodiments and the modifications. The invention includes a configuration in which a non-essential portion in the configuration described in the embodiment or the like is substituted. The invention includes a configuration in which the same functional effects as the configuration described in the embodiment or the like are obtained, or a configuration in which the same objects can be attained. The invention includes a configuration in which the known technique is added to the configuration described in the embodiment or the like.