JP6811552B2 - Inkjet head and inkjet recorder - Google Patents

Description

Embodiments of the present invention relate to an inkjet head and an inkjet recording device.

There is an inkjet head that ejects ink that has flowed into a plurality of grooves provided in the piezoelectric member by deforming the share mode of the piezoelectric member. In such an inkjet head, electrodes are formed so as to sandwich a piezoelectric member on the side wall of the groove. When a voltage is applied to the pair of electrodes sandwiching the piezoelectric member, the piezoelectric member is deformed. By deforming the piezoelectric member, the inkjet head changes the pressure in the groove to eject ink.

Since the inkjet head configured as described above deforms the piezoelectric member forming the side wall of the groove for ejecting ink, one side wall of the groove on both sides is also deformed with respect to this groove. Therefore, ink may be ejected from the grooves on both sides. Therefore, there is an inkjet head that allows ink to flow into every other groove.

The above-mentioned inkjet head inputs a drive waveform to electrodes formed in a plurality of grooves into which ink flows through via a common electrode, and for each electrode formed in a plurality of grooves in which ink does not flow in. Input the drive waveform according to the print data. However, when a drive waveform is input from one drive circuit that drives the common electrode via the common electrode, the impedance of the drive circuit that outputs the drive waveform and the impedance of the common electrode depends on how many piezoelectric members are driven at the same time. The resulting voltage drop is different. As a result, there is a possibility that the drive waveform input to the electrode will differ depending on the print data. Therefore, the reliability of printing may be impaired.

Japanese Unexamined Patent Publication No. 10-315451

An object to be solved by the present invention is to provide a highly reliable inkjet head and an inkjet recording device.

The inkjet head according to one embodiment includes a piezoelectric member, a nozzle plate, an ink chamber, a plurality of first electrodes, a plurality of second electrodes, and a drive circuit. The piezoelectric member is provided with a plurality of first grooves and a plurality of second grooves alternately formed on the surface thereof, each of which is composed of a pair of side surfaces and a bottom surface. The nozzle plate closes the surface of the piezoelectric member in which the nozzle is arranged so as to at least align with the position of the first groove. The ink chamber communicates with the first groove to supply ink. The first electrode is provided on at least one of the pair of side surfaces of each of the first grooves. The second electrode is provided on the side surface facing the first electrode with the piezoelectric member of each of the second grooves configured as a gap through which the ink does not flow . The drive circuit is provided for each of the first electrodes and is provided for each of the second electrodes and corresponds to print data and a plurality of first drivers for inputting a common waveform of the first electrode to each of the first electrodes . It has a plurality of second drivers that input the waveform of the second electrode to each of the second electrodes .

FIG. 1 is a diagram for explaining an example of a configuration of an inkjet recording device according to an embodiment. FIG. 2 is a diagram for explaining an example of a configuration of a control system of an inkjet recording device according to an embodiment. FIG. 3 is a diagram for explaining an example of the configuration of the inkjet head according to the embodiment. FIG. 4 is a diagram for explaining an example of a partial configuration of the inkjet head according to the embodiment. FIG. 5 is a diagram for explaining an example of a partial configuration of the inkjet head according to the embodiment. FIG. 6 is a diagram for explaining an example of a partial configuration of the inkjet head according to the embodiment. FIG. 7 is a diagram for explaining an example of a partial configuration of the inkjet head according to the embodiment. FIG. 8 is a diagram for explaining an example of a partial configuration of the inkjet head according to the embodiment. FIG. 9 is a diagram for explaining an example of the configuration of the drive circuit of the inkjet head according to the embodiment. FIG. 10 is a diagram for explaining an example of the configuration of the first driver of the inkjet head according to the embodiment. FIG. 11 is a diagram for explaining an example of the configuration of the second driver of the inkjet head according to the embodiment. FIG. 12 is a diagram for explaining an example of the operation of the inkjet head according to the embodiment.

Hereinafter, an inkjet head and an inkjet recording device according to an embodiment will be described with reference to the drawings.
First, the inkjet printer 1 according to the embodiment will be described. FIG. 1 is an explanatory diagram showing a configuration example of the inkjet printer 1 according to the embodiment. FIG. 2 is an explanatory diagram showing a configuration example of a main part of the control system of the inkjet printer 1.

The inkjet printer 1 is an example of an inkjet recording device. The inkjet recording device is not limited to this, and may be another device such as a copying machine.

As shown in FIG. 1, the inkjet printer 1 performs various processes such as image formation while transporting the recording paper P, which is a recording medium, for example. The inkjet printer 1 includes a housing 10, a paper feed cassette 11, a paper output tray 12, a transport device 13, a holding roller (drum) 14, a holding device 15, an image forming device 16, and a static elimination peeling device 17. The reversing device 18 and the cleaning device 19 are provided. Further, the inkjet printer 1 includes a main control unit 31, an operation I / F 32, a communication I / F 33, a transfer control unit 34, a print data output unit 35, and an ink supply unit 36 as main control systems. ..

The paper feed cassette 11 accommodates a plurality of recording papers P. The paper cassette 11 is arranged, for example, in the housing 10.

The output tray 12 is provided in the housing 10. The paper output tray 12 accommodates the recording paper P image-formed and discharged by the inkjet printer 1.

The transfer device 13 has a plurality of guides and a plurality of transfer rollers arranged along a path through which the recording paper P is conveyed. The transfer roller conveys the recording paper P by being driven by a motor that operates under the control of the transfer control unit 34 and rotating. Some of the guides are rotated by a motor that operates under the control of the transport control unit 34 to switch the transport path for transporting the recording paper P. The transport device 13 transports the recording paper P housed in the paper feed cassette 11 to the holding roller 14. Further, the transport device 13 transports the recording paper P supplied from the holding roller 14 to the output tray 12 or the reversing device 18. The transport device 13 switches the transport destination for transporting the recording paper P between the output tray 12 and the reversing device 18 based on, for example, the control of the transport control unit 34.

The holding roller 14 has a cylindrical frame formed by a conductor and a thin insulating layer (not shown) formed on the surface of the frame. This frame is grounded (grounded). The holding roller 14 conveys the recording paper P by rotating the frame while holding the recording paper P on the surface of the frame.

The holding device 15 attracts the recording paper P conveyed from the conveying device 13 to the surface of the frame of the holding roller 14 and holds it. For example, the holding device 15 presses the recording paper P against the frame of the holding roller 14, and then attracts the recording paper P to the surface of the frame of the holding roller 14 by the electrostatic force generated by charging the recording paper P. ..

The image forming apparatus 16 forms an image on the recording paper P conveyed by the holding roller 14. The image forming apparatus 16 has a plurality of inkjet heads 21. The image forming apparatus 16 has, for example, a plurality of inkjet heads 21 corresponding to each color such as cyan, magenta, yellow, and black. The inkjet head 21 has a nozzle for ejecting ink. The inkjet head 21 is provided with a nozzle for ejecting ink so as to face the surface of the frame of the holding roller 14.

The image forming apparatus 16 forms an image on one surface of the recording paper P by ejecting ink from the recording paper P held on the surface of the frame of the holding roller 14 by the inkjet head 21. The image forming apparatus 16 operates each of the inkjet heads 21 based on the print data output from the print data output unit 35 to form an image corresponding to the print data on the recording paper P.

The static eliminator peeling device 17 peels the recording paper P from the holding roller 14 by removing static electricity from the recording paper P held by the frame of the holding roller 14. For example, the static elimination stripping device 17 removes static charge from the recording paper P by supplying an electric charge to the recording paper P, and inserts a claw between the recording paper P and the surface of the frame of the holding roller 14. The recording paper P is peeled off from 14. The recording paper P peeled off from the holding roller 14 is supplied to the transport device 13.

The reversing device 18 reverses the front and back surfaces of the recording paper P and / or the front and back, and supplies the recording paper P to the holding roller 14. That is, the reversing device 18 supplies the recording paper P to the holding roller 14 with the surface on which the image of the recording paper P peeled from the holding roller 14 formed by the static elimination peeling device 17 is formed toward the surface of the frame of the holding roller 14. ..

The cleaning device 19 removes ink and paper dust adhering to the surface of the frame of the holding roller 14.

The main control unit 31 controls the transfer of the recording paper P by the transfer device 13 of the inkjet printer 1 and the formation of an image on the recording paper P by the image forming device 16. The main control unit 31 is composed of a processor such as a CPU, a program memory, a working memory, and various interfaces. The main control unit 31 realizes various processing functions by executing a program stored in the program memory by the processor.

For example, the main control unit 31 generates print data for forming an image by the image forming apparatus 16 based on the data (for example, a printing instruction) received via the communication I / F 33. The print data is composed of, for example, a plurality of lines composed of a plurality of pixels arranged side by side. The main control unit 31 supplies the generated print data to the print data output unit 35.

The operation I / F 32 is connected to an operation unit (not shown). The operation I / F 32 supplies an operation signal corresponding to an operation input to the operation unit to the main control unit 31.

The communication I / F 33 is connected to a network (not shown), an electronic device, or the like. The communication I / F 33 can send and receive data to and from other electronic devices directly or via a network. The communication I / F 33 is configured as, for example, a LAN connector, a USB port, a wireless LAN module, or the like.

The transport control unit 34 controls the operation of the transport device 13. For example, the transfer control unit 34 controls the operation of the motor for driving the transfer roller of the transfer device 13. Further, for example, the transport control unit 34 controls the operation of the motor for rotating the guide.

The print data output unit 35 outputs print data for forming an image by the image forming apparatus 16 to the image forming apparatus 16. The print data output unit 35 includes, for example, an image memory for temporarily storing print data. The print data output unit 35 stores the print data supplied from the main control unit 31 in the image memory, and sequentially outputs the print data stored in the image memory to the image forming apparatus 16.

The ink supply unit 36 supplies the ink in the ink tank (not shown) in which the ink is held to the inkjet head 21 of the image forming apparatus 16 under the control of the main control unit 31. The ink supply unit 36 includes, for example, a tube that connects the ink tank and the inkjet head 21, and a pump that supplies the ink in the ink tank to the inkjet head 21 via the tube.

When the inkjet printer 1 having the above configuration receives data instructing printing via the communication I / F 33, the main control unit 31 generates print data. The main control unit 31 supplies the generated print data to the image forming apparatus 16 via the print data output unit 35. The transport control unit 34 takes out the recording paper P from the paper feed cassette 11 and supplies it to the holding roller 14. The holding roller 14 conveys the recording paper P while holding it. The image forming apparatus 16 operates each of the inkjet heads 21 based on the print data to form an image on the recording paper P conveyed by the holding roller 14.

Next, the detailed configuration of the inkjet head 21 will be described. 3 to 8 are diagrams for explaining a configuration example of the inkjet head 21.

FIG. 3 is an exploded perspective view of the inkjet head 21.

As shown in FIG. 3, the inkjet head 21 is, for example, a side shooter type share mode type on-demand inkjet head. The inkjet head 21 is mounted on the above-mentioned inkjet printer 1 and ejects ink toward the recording paper P.

The inkjet head 21 includes a base material 100, a nozzle plate 300, a frame member 200, and a housing 400. The housing 400 is provided with a drive circuit 40 for operating the ink tank and the inkjet head 21.

The inkjet head 21 has two piezoelectric members 118 extending in the longitudinal direction of the base material 100 at the center of the mounting surface 121 of the base material 100.

Further, as will be described in detail later, an ink chamber 116 (FIG. 7) surrounded by a base material 100, a nozzle plate 300, and a frame member 200 is provided inside the inkjet head 21.

As shown in FIG. 3, the base material 100 is formed in the shape of a rectangular plate. In this embodiment, alumina is used as the material of the base material 100. The material of the base material 100 is not limited to this, and may be other semiconductors such as silicon carbide (SiC) and a germanium substrate. Further, the material of the base material 100 may be other materials such as ceramics, glass, quartz, resin, or metal. As the ceramics, for example, zirconia, silicon carbide, silicon nitride, or nitrides, carbides, or oxides such as barium titanate can be used. As the resin, for example, a plastic material such as ABS (acrylonitrile-butadiene-styrene), polyacetal, polyamide, polycarbonate, or polyether sulfone can be used. As the metal, for example, aluminum or titanium can be used. When a metal material is used as the base material 100, it is necessary to cover the mounting surface 121 with an insulating material.

The base material 100 has a mounting surface 121. Piezoelectric members 118 are provided side by side in two rows at the center of the mounting surface 121. Each piezoelectric member 118 has a trapezoidal cross section in the direction between rows, and is arranged in parallel with each other separated from each other. The base material 100 is provided with a plurality of supply ports 125 and a plurality of discharge ports 126 along the longitudinal direction of the piezoelectric member 118.

The plurality of supply ports 125 are provided between the two piezoelectric members 118, that is, along the central portion of the base material 100 in the longitudinal direction of the base material 100. Each supply port 125 penetrates the base material 100 and communicates with an ink tank (not shown). In other words, the ink supplied from the ink tank to the inkjet head 21 through the supply port 125 flows into the ink chamber 116.

As shown in FIG. 3, the discharge ports 126 are provided side by side in two rows on the outside of the two piezoelectric members 118 with the supply port 125 sandwiched between them. Each discharge port 126 penetrates the base material 100 and communicates with an ink tank (not shown), and discharges the ink in the ink chamber 116 to the ink tank. Therefore, the ink circulates between the ink tank and the ink chamber 116 through the supply port 125 and the discharge port 126.

As shown in FIG. 3, the nozzle plate 300 is formed of, for example, a rectangular thin film (film) of polyimide. The material of the nozzle plate 300 is not limited to this, and may be other semiconductors such as silicon carbide (SiC) and a germanium substrate. As the other resin material, for example, other types of plastic materials such as polyimide, ABS, polyacetal, polyamide, polycarbonate, and polyether sulfone can be used. Further, as the ceramics, for example, nitrides such as zirconia, silicon carbide, silicon nitride, barium titanate, or oxides can be used. Further, the nozzle plate 300 may be formed of a metal material. As the metal material, for example, aluminum, SUS, or titanium can be used. When a metal material is used for the nozzle plate 300, an insulating material is formed at a position in contact with the first electrode 134 and the second electrode 135.

An ink-repellent film is formed on the surface 302 of the nozzle plate 300 on the ink ejection side (not shown). The ink-repellent film is formed of, for example, a silicon-based liquid-repellent material or a fluorine-containing organic material having liquid-repellent properties.

The nozzle plate 300 is arranged so as to face the mounting surface 121 of the base material 100 via the frame member 200. The nozzle plate 300 has a plurality of nozzles 301 that penetrate the nozzle plate 300. The plurality of nozzles 301 are arranged side by side in two rows along the longitudinal direction of the nozzle plate 300.

As shown in FIG. 3, the frame member 200 is formed in a rectangular frame shape by, for example, a nickel alloy. The material of the frame member 200 is not limited to this, and may be other semiconductors such as silicon carbide (SiC) and a germanium substrate. As the other resin material, for example, other types of plastic materials such as polyimide, ABS, polyacetal, polyamide, polycarbonate, and polyether sulfone can be used. Further, as the ceramics, for example, nitrides such as zirconia, silicon carbide, silicon nitride, barium titanate, or oxides can be used. The frame member 200 is arranged between the mounting surface 121 of the base material 100 and the nozzle plate 300. The frame member 200 has a size that surrounds the two piezoelectric members 118 and surrounds all the nozzles 301. When a metal material is used as the frame member, an insulating material is formed at a position in contact with the first wiring 136 and the second wiring 137.

The piezoelectric member 118 is formed of, for example, lead zirconate titanate (PZT). The piezoelectric member 118 is formed by laminating two plate-shaped piezoelectric bodies so that their polarization directions face each other. The piezoelectric member 118 according to the present embodiment has a rod-shaped outer shape extending in the longitudinal direction. The piezoelectric material is not limited to this, and for example, PTO (PbTiO ₃ : lead titanate), PMNT (Pb (Mg _1/3 Nb _2/3 ) O _3- PbTiO ₃ ), PZNT (Pb (Zn _{1 /} Zn _{1 /} )). Various piezoelectric materials such as ₃ Nb _2/3 ) O _3- PbTIO ₃ ), ZnO, and AlN can be used.

As shown in FIG. 3, the piezoelectric member 118 is adhered to the mounting surface 121 of the base material 100. As this adhesive, for example, a thermosetting epoxy-based adhesive is used.

FIG. 4 is an enlarged perspective view showing the vicinity of the piezoelectric members 118 arranged in two rows on the base material 100. In FIG. 4, a part of the nozzle plate 300 is omitted in order to make the structure of the piezoelectric member 118 and the like easier to see.

As shown in FIG. 4, the piezoelectric member 118 has an upper surface 118c parallel to the mounting surface 121 of the base material 100 and two inclined members inclined so as to spread from both ends of the upper surface 118c in the lateral direction toward the mounting surface 121. It has an inclined surface 118b. The piezoelectric member 118 has a plurality of first grooves 131 (hereinafter, also referred to as pressure chambers 131) and a plurality of second grooves 132 (hereinafter, also referred to as air chambers 132) extending from the surface 118a of the base material 100 in the lateral direction. ) Alternately. Both ends of the first groove 131 and the second groove 132 are connected to the inclined surface 118b. In the present embodiment, the first groove 131 and the second groove 132 are grooves formed in the same shape, respectively. The shapes of the first groove 131 and the second groove 132 may be different. From a different point of view, the piezoelectric member 118 has a plurality of side walls 133 forming these first groove 131 and second groove 132. The side wall 133 is, in other words, a convex portion provided between the first groove 131 and the second groove 132.

Wall members 117 are provided at both ends of the second groove 132. The wall material 117 seals both ends of the second groove 132. The wall material 117 has an upper surface 117a provided flush with the upper surface 118c of the piezoelectric member 118. The upper surface 118c of the piezoelectric member 118 and the upper surface 117a of the wall material 117 are adhered to the nozzle plate 300. As a result, the ink filled in the ink chamber 116 is prevented from entering the second groove 132.

FIG. 5 is an enlarged cross-sectional view of a portion of the inkjet head 21 of FIG. 3 cut by F4-F4 in the longitudinal direction.

As shown in FIG. 5, the nozzle 301 of the nozzle plate 300 is provided so that one nozzle 301 communicates with one first groove 131. That is, the nozzle plate 300 has two rows of nozzles 301 corresponding to the first groove 131 provided in the two rows of piezoelectric members 118. On the other hand, there is no nozzle corresponding to the second groove 132.

Here, the structure of the ink chamber 116 and the way the ink flows will be described in detail.

FIG. 6 is a partially enlarged plan view of one of the piezoelectric members 118 of the inkjet head 21 shown in FIG. FIG. 7 is a cross-sectional view of the inkjet head 21 shown in FIG. 6 cut by F7-F7. FIG. 8 is a cross-sectional view of the inkjet head 21 shown in FIG. 6 cut by F8-F8.

The ink chamber 116 is a space surrounded by the mounting surface 121 of the base material 100, the nozzle plate 300, and the frame member 200. The ink chamber 116 includes a first ink chamber 116a and a second ink chamber 116b. The first ink chamber 116a is a space between two piezoelectric members 118. A plurality of supply ports 125 communicate with the first ink chamber 116a. On the other hand, the second ink chamber 116b is a space on the frame member 200 side (outside) of the two piezoelectric members 118. A plurality of discharge ports 126 communicate with each other in the second ink chamber 116b.

The ink in the ink tank is supplied to the ink chamber 116 by a pump (not shown). At this time, the ink is supplied from the ink tank to the first ink chamber 116a. The ink chamber 116 is gradually filled with the supplied ink. Specifically, the ink that has flowed into the first ink chamber 116a flows out toward the two outer second ink chambers 116b through the plurality of first grooves 131 of the piezoelectric members 118 on both sides thereof. As a result, the entire ink chamber 116 surrounded by the frame member 200 is filled with ink. Then, the ink that has flowed to the second ink chamber 116b is returned to the ink tank through the plurality of discharge ports 126.

As shown in FIG. 7, both ends of the plurality of second grooves 132 alternately arranged between the plurality of first grooves 131 are closed by the wall material 117, so that ink does not enter. .. Therefore, while the plurality of first grooves 131 function as a part of the flow path for circulating the ink, the plurality of second grooves 132 function as dummy chambers in which the ink does not enter.

Next, the electrodes and wiring arranged on the base material 100 and the piezoelectric member 118 will be described.

As shown in FIG. 5, the first electrode 134 is formed in the first groove 131, and the second electrode 135 is formed in the second groove 132. In the example of FIG. 5, one first electrode 134 is formed in one first groove 131, and two second electrodes 135 are formed in one second groove 132. The first electrode 134 is formed over a pair of side surfaces 138 and a bottom surface 139 of the first groove 131. The second electrode 135 is formed over each side surface 140 of the second groove 132 and a part of the bottom surface 141.

As shown in FIG. 6, on the base material 100 of the second ink chamber 116b, a first wiring 136 extending to the first groove 131 and a second wiring 137 extending to the second groove are provided. In the example of FIG. 6, one first wiring 136 is provided for each first groove 131, and two second wirings 137 are provided for each second groove 132. One end of the first wiring 136 is connected to the first electrode 134 formed in the first groove 131, and the other end of the first wiring 136 is connected to the drive circuit 40 shown in FIG. 3 via the flexible wiring board 40a. ing. Further, one end of the two second wirings 137 is connected to each of the two second electrodes 135 formed in the second groove 132, and the other end of the second wiring 137 is shown in FIG. 3 via the flexible wiring board 40a. It is connected to the drive circuit 40 shown.

The first electrode 134 and the second electrode 135 provided in the first groove 131 and the second groove 132 are formed of, for example, a nickel thin film. The first electrode 134 and the second electrode 135 are not limited to this, and may be formed of, for example, thin films of Pt (platinum), Al (aluminum), and Ti (titanium). Further, as the material of the first electrode 134 and the second electrode 135, Cu (copper), A1 (aluminum), Ag (silver), Ti (titanium), W (tungsten), Mo (molybdenum), Au (gold), etc. Other materials can also be used.

Further, the second wiring 137 connected to the second electrode 135 is covered with an insulating coating 119 formed of an insulating material. Further, the insulating coating 119 may be provided so as to further cover the first wiring 136. The insulating coating 119 is provided so as to cover the portion where the second wiring 137 comes into contact with the ink filled in the ink chamber 116b. With this configuration, it is possible to prevent the ink from being applied with a potential difference generated between the first electrode 134 and the second wiring 137 or between the plurality of second wirings 137. Further, the insulating coating 119 may be extended to an adhesive portion between the frame member 200 and the first wiring 136 and the second wiring 137.

With the above configuration, the first electrode 134 provided in the first groove 131 corresponding to one nozzle and the side surface 140 of the second groove 132 facing the first electrode 134 with the piezoelectric member 118 interposed therebetween are provided. The piezoelectric member 118 can be deformed by the potential difference between the second electrode 135 and the second electrode 135. That is, an actuator that changes the volume of the first groove 131 is configured by the piezoelectric member 118, the first electrode 134 sandwiching the piezoelectric member 118, and the second electrode 135. In this way, ink is ejected from the actuator composed of the piezoelectric member 118, the first electrode 134, and the second electrode 135, the first groove 131 filled with ink, and the nozzle 301 corresponding to the first groove 131. One channel is configured.

Next, the configuration of the drive circuit 40 of the inkjet head 21 will be described. 9 to 11 are diagrams for explaining the configuration of the drive circuit 40. The drive circuit 40 controls the ejection of ink from the nozzle 301 for each channel including the nozzle 301, the first groove 131, and the actuator that changes the volume of the first groove 131 by deforming. Therefore, based on the print data, the drive circuit 40 faces the first electrode 134 provided in the first groove 131 corresponding to one nozzle, and the first electrode 134 and the piezoelectric member 118 so as to face each other. The potential difference between the second electrode 135 provided on the side surface 140 of the groove 132 and the second electrode 135 is controlled for each channel. As a result, the drive circuit 40 drives an actuator that constitutes a channel according to the print data to change the volume of the first groove 131, and ejects ink from the nozzle 301.

As shown in FIG. 9, the drive circuit 40 includes a waveform generation circuit 41, a channel control circuit 42, a plurality of first drivers 43, and a plurality of second drivers 44. For example, the drive circuit 40 includes a first driver 43 for each first electrode 134 and a second driver 44 for each second electrode 135. That is, the drive circuit 40 includes one first driver 43 and two second drivers 44 for each channel.

The waveform generation circuit 41 generates and outputs a main waveform and a sub-waveform. The main waveform and the sub-waveform are rectangular pulses consisting of high-level and low-level signals, respectively. The terminal for outputting the main waveform of the waveform generation circuit 41 is connected to each first driver 43. Further, the terminal for outputting the sub-waveform of the waveform generation circuit 41 is connected to each second driver 44. That is, the waveform generation circuit 41 inputs the same main waveform to each first driver 43, and inputs the same sub-waveform to each second driver 44. The waveform generation circuit 41 may be configured to input different sub-waveforms for each channel to the second driver 44 instead of inputting the same sub-waveform to each second driver 44.

The channel control circuit 42 switches between the on state and the off state of the second driver 44. The channel control circuit 42 generates a channel control signal for each channel based on the print data and inputs the channel control signal to the second driver 44 corresponding to each channel, so that the second driver 44 is turned on and off for each channel. To switch. The channel control signal is a square pulse consisting of high level and low level signals. The channel control circuit 42 turns on the second driver 44 by inputting a high-level channel control signal to the second driver 44. Further, the channel control circuit 42 turns off the second driver 44 by inputting a low-level channel control signal to the second driver 44.

The channel control circuit 42 ejects ink from the nozzle 301 by turning on the second driver 44 corresponding to the channel for ejecting ink. Further, the channel control circuit 42 turns off the second driver 44 corresponding to the channel that does not eject ink. As a result, the channel control circuit 42 applies a voltage to the actuators constituting the channels for ejecting ink to deform them. As a result, the channel control circuit 42 drives an actuator that constitutes a channel according to the print data to change the volume of the first groove 131, and ejects ink from the nozzle 301.

The first driver 43 applies a potential to the first electrode 134 according to the input waveform. For example, the first driver 43 is configured as a NOT circuit. FIG. 10 shows a configuration example of the first driver 43. For example, the first driver 43 includes a first switching element 51 and a second switching element 52. The first switching element 51 is composed of, for example, p-MOS. The second switching element 52 is composed of, for example, n-MOS. The gates of the first switching element 51 and the second switching element 52 are connected to the output terminal of the main waveform of the waveform generation circuit 41. The source of the first switching element 51 is connected to a drive power supply (not shown) having a voltage of Vd. The drain of the first switching element 51 is connected to the drain of the second switching element 52 and the output terminal of the first driver 43. The source of the second switching element 52 is connected to the GND.

The second driver 44 applies a potential to the second electrode 135 according to the input waveform. For example, the second driver 44 is configured as a NOT circuit whose on state and off state can be controlled by a channel control signal. FIG. 11 shows a configuration example of the second driver 44. For example, the second driver 44 includes a first logic element 61, a second logic element 62, a third logic element 63, a first switching element 64, and a second switching element 65.

The first logic element 61 is composed of, for example, a NOT circuit. The second logic element 62 is composed of, for example, an OR circuit. The third logic element 63 is composed of, for example, an AND circuit. The first switching element 64 is composed of, for example, p-MOS. The second switching element 65 is composed of, for example, n-MOS.

The channel control signal output from the channel control circuit 42 is input to the first logic element 61. The first logic element 61 inverts and outputs the channel control signal.

The output of the first logic element 61 and the sub-waveform output from the waveform generation circuit 41 are input to the second logic element 62. The second logic element 62 outputs the logical sum (logical product of negative logic) of the output of the first logic element 61 and the sub-waveform.

The channel control signal output from the channel control circuit 42 and the sub-waveform output from the waveform generation circuit 41 are input to the third logic element 63. The third logic element 63 outputs the logical product of the channel control signal and the sub-waveform.

The gate of the first switching element 64 is connected to the output terminal of the second logic element 62. The gate of the second switching element 65 is connected to the output terminal of the third logic element 63. The source of the first switching element 64 is connected to a drive power supply (not shown) having a voltage of Vd. The drain of the first switching element 64 is connected to the drain of the second switching element 65 and the output terminal of the second driver 44. The source of the second switching element 65 is connected to the GND.

The configurations of the first driver 43 and the second driver 44 are not limited to the above configurations. The configuration of the first driver 43 and the second driver 44 may be any configuration as long as the same truth value as the truth value obtained by the above configuration can be obtained.

Next, the operation of the inkjet head 21 will be described.
For example, when the main control unit 31 receives a print instruction, it generates print data and inputs the print data to the drive circuit 40 of the inkjet head 21 via the print data output unit 35.

Further, the ink supply unit 36 supplies the ink in the ink tank to the inkjet head 21 via the tube and the plurality of supply ports 125 under the control of the main control unit 31. The ink supplied to the inkjet head 21 through the supply port 125 flows into the first groove 131 from one end of the first groove (pressure chamber) 131 communicating with the first ink chamber 116a. The ink flowing out from the first groove 131 flows into the second ink chamber 116b. The ink flowing out to the second ink chamber 116b is discharged to the ink tank through the plurality of discharge ports 126.

The supply amount and the discharge amount of the ink supplied to the ink chamber 116 are adjusted to values that discharge the air bubbles inside the ink chamber 116 and prevent the ink from being pushed out from the nozzle 301. Further, the ink in the ink chamber 116 circulates between the ink chamber 116 and the ink tank through the supply port 125 and the discharge port 126 so that the ink does not stay in the ink chamber 116.

The drive circuit 40 that has received the print data applies a potential to the first electrode 134 and the second electrode 135 corresponding to each channel, respectively, and creates a potential difference between the first electrode 134 and the second electrode 135 according to the print data. By generating it, the actuator is driven for each channel.

FIG. 12 is a timing chart for explaining each signal in the drive circuit 40 and the applied voltage of the actuator. The time Tt shown in FIG. 12 indicates the time required for ejecting ink. This time Tt includes the preparation time for ink ejection, the ink ejection time, and the time for post-treatment. In FIG. 12, the difference between the potential of the first electrode 134 and the potential of the second electrode 135 is shown as the applied voltage applied to the actuator.

The main waveform generated by the waveform generation circuit 41 is set to a high level at a timing corresponding to the preparation time for ink ejection in one time Tt. Further, the sub-waveform generated by the waveform generation circuit 41 is set to a high level at a timing corresponding to the ink ejection time in one time Tt. Further, the channel control signal generated by the channel control circuit 42 is switched between high level and low level with the length corresponding to the time Tt as the minimum unit.

The first driver 43 lowers the potential of the first electrode 134 connected to the output terminal to GND when the main waveform is at a high level, and the first electrode connected to the output terminal when the main waveform is at a low level. The potential of 134 is raised to the voltage Vd of the drive power supply.

Further, the second driver 44 lowers the potential of the second electrode 135 connected to the output terminal to GND when the channel control signal is at a high level and the sub-waveform is at a high level, and the channel control signal is at a high level. When the sub-waveform is low level, the potential of the second electrode 135 connected to the output terminal is raised to the voltage Vd of the drive power supply. Further, when the channel control signal is low level, the second driver 44 opens the second electrode 135 connected to the output terminal regardless of the high level and low level of the sub-waveform. As a result, the potential of the second electrode 135 is raised to a potential equivalent to the potential of the first electrode 134 driven by the main waveform output from the first driver 43 via the capacitance of the piezoelectric member 118. Or it will be lowered. That is, when the channel control signal is at a low level, the potential of the second electrode 135 follows the potential equivalent to that of the first electrode 134.

The potential difference obtained by subtracting the potential of the second electrode 135 from the potential of the first electrode 134 controlled in this way is the voltage applied to the actuator.

As a result, as shown in FIG. 12, in the channel where the channel control signal is high level, the potential of the first electrode 134 is lowered to GND at the timing when the main waveform is high level and the sub waveform is low level. , The potential of the second electrode 135 is raised to the voltage Vd. As a result, the applied voltage −Vd is applied to the actuator composed of the first electrode 134, the second electrode 135, and the piezoelectric member 118 between them.

When the applied voltage −Vd is applied to the actuator, the actuator curves from the first electrode 134 side to the second electrode 135 side. That is, the side walls 133 forming the side surface 138 of the first groove 131 are curved from the first groove 131 to the second groove 132 side, respectively. As a result, the volume of the first groove 131 is increased, and the pressure in the first groove 131 is reduced. As a result, ink flows into the first groove 131 from the first ink chamber 116a.

Further, in the channel where the channel control signal is high level, the potential of the first electrode 134 is raised to the voltage Vd at the timing when the main waveform is low level and the sub waveform is high level, and the potential of the second electrode 135 is raised. It will be lowered to GND. As a result, the applied voltage + Vd is applied to the actuator composed of the first electrode 134, the second electrode 135, and the piezoelectric member 118 between them.

When the applied voltage + Vd is applied to the actuator, the actuator bends from the second electrode 135 side to the first electrode 134 side. That is, the side walls 133 forming the side surface 138 of the first groove 131 are curved from the second groove 132 to the first groove 131 side, respectively. As a result, the volume of the first groove 131 is reduced, and the pressure in the first groove 131 is increased. As a result, the ink in the first groove 131 is ejected from the nozzle 301 communicating with the first groove 131.

On the other hand, in a channel where the channel control signal is at a low level, the potential of the first electrode 134 and the potential of the second electrode 135 always match, so that no potential difference is given to the actuator regardless of the level of the main waveform and the sub waveform. , No ink is ejected. In this way, ink can be ejected on demand only from the channel selected by the channel control signal.

Next, the operation and effect of the inkjet head according to the present embodiment will be described.

According to the configuration as described above, the inkjet head applies an electric potential to a plurality of first electrodes provided for each channel by a plurality of first drivers provided for each first electrode, and uses the first electrodes and the like. A potential is applied to a plurality of second electrodes provided so as to face each other with the piezoelectric member interposed therebetween by a plurality of second drivers corresponding to the second electrodes. That is, the inkjet head does not apply an electric potential to each first electrode from one driver by a common electrode, but from a set of each first driver and second driver provided for each first electrode and second electrode, respectively. An electric potential is applied to each of the first electrode and the second electrode independently for each channel. In this way, the common impedance portion that gives a drive waveform to each piezoelectric member is eliminated. Therefore, unlike the conventional drive circuit, there is no problem that the voltage drop differs depending on how many piezoelectric members are driven at the same time and the drive waveform input to the electrode differs depending on the content of the print data. .. As a result, the inkjet head can perform stable printing regardless of the print content. In addition, uneven density and deterioration of print quality can be suppressed, and printing reliability can be improved.

Further, since the inkjet head is provided with the first driver for each first electrode, it is not necessary to wire the common electrodes three-dimensionally, so that the manufacturing cost can be suppressed.

Further, the inkjet head can control the operation of the actuator in three stages by the combination of the potentials given to the first electrode and the second electrode. That is, the inkjet head can drive the actuator with an amplitude corresponding to 0 times, 1 time, and 2 times the voltage of the drive power supply of the first driver and the second driver. By making the drive voltage of the actuator up to twice the voltage of the drive power supply, the drive amplitude of the actuator can be made large even if the voltage of the drive power supply is low, that is, the voltage efficiency is improved. Further, by controlling the operation of the actuator in three stages, it is possible to efficiently and finely adjust the ejection characteristics related to the printing quality and the printing speed such as the ejection speed, the ejection volume, and the damping after ejection.

Further, in the inkjet head, the potential can be set to the same value for each first electrode by driving each first driver that gives a potential to each first electrode by a common main waveform. That is, the inkjet head is configured so that a potential difference does not occur between the different first electrodes. As a result, the inkjet head can prevent the first electrode from giving a potential difference to the ink. Further, the inkjet head is provided with a wall material for preventing ink from flowing into the second groove provided with the second electrode. As a result, the inkjet head can prevent the second electrode from giving a potential difference to the ink. The inkjet head configured in this way can prevent an electrochemical reaction from occurring in the ink by giving a potential difference to the ink.

In the above-described embodiment, the inkjet head 21 has been described as having a pair of side walls 133 forming a pair of side surfaces 138 of the first groove 131 as actuators, but the present invention is not limited to this configuration. In the inkjet head, one of the pair of side wall 133s forming the pair of side surfaces 138 of the first groove 131 may be configured as an actuator.

Further, in the above-described embodiment, it has been described that the first electrode 134 of the inkjet head 21 is formed over the pair of side surfaces 138 and the bottom surface 139 of the first groove 131, but the configuration is not limited to this. The first electrode 134 may be formed on all or a part of the pair of side surfaces 138 of the first groove 131, respectively. In this case, the first electrodes 134 formed on the pair of side surfaces 138 of the first groove 131 for each channel are connected to the output terminals of the first driver 43 corresponding to the channels by the first wiring 136.

Further, in the above-described embodiment, it has been described that the drive circuit 40 of the inkjet head 21 has a configuration in which one second driver 44 applies a potential to the two second electrodes 135 corresponding to the channels. Not limited to. The drive circuit 40 may be configured to include a second driver 44 for each second electrode 135.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.
The scope of claims at the time of filing the application of the present application is added below.
[C1]
A piezoelectric member having a plurality of first grooves and a plurality of second grooves alternately provided on the surface thereof, each of which is composed of a pair of side surfaces and a bottom surface.
A nozzle plate that closes the surface of the piezoelectric member in which the nozzle is arranged at least according to the position of the first groove, and
An ink chamber that communicates ink to the first groove and
A first electrode provided on at least one of the pair of side surfaces of each first groove,
A second electrode provided on the side surface facing the first electrode with the piezoelectric member of each second groove interposed therebetween.
A plurality of first drivers provided for each of the first electrodes and inputting a common first drive waveform to each of the first electrodes, and provided for each of the second electrodes and corresponding to print data, respectively. A drive circuit having a plurality of second drivers for inputting a second drive waveform for each of the second electrodes to each of the second electrodes.
An inkjet head equipped with.
[C2]
The first electrode is formed over a pair of side surfaces constituting the first groove.
The inkjet head according to C1, wherein the second electrode is formed on the side surface facing the first electrode with the piezoelectric member of the pair of the second grooves adjacent to the first groove interposed therebetween.
[C3]
The drive circuit is common to the pair of the second electrodes formed on the side surfaces facing the first electrode with the piezoelectric member of the pair of the second grooves adjacent to the first groove interposed therebetween. The inkjet head according to C2, which inputs a second drive waveform.
[C4]
The inkjet head according to C1, wherein the second groove is formed as a gap through which the ink does not flow.
[C5]
The inkjet head according to any one of C1 to 4 and
A transport device that transports the recording paper to a position facing the nozzle,
An inkjet recording device comprising.

1 ... Inkjet printer, 10 ... Housing, 11 ... Paper cassette, 12 ... Paper output tray, 13 ... Conveyor, 14 ... Holding roller, 15 ... Holding device, 16 ... Image forming device, 17 ... Static elimination peeling device, 18 ... inverting device, 19 ... cleaning device, 21 ... inkjet head, 31 ... main control unit, 34 ... transfer control unit, 35 ... print data output unit, 40 ... drive circuit, 41 ... waveform generation circuit, 42 ... channel control circuit, 43 ... 1st driver, 44 ... 2nd driver, 51 ... 1st switching element, 52 ... 2nd switching element, 61 ... 1st logic element, 62 ... 2nd logic element, 63 ... 3rd logic element, 64 ... 1 switching element, 65 ... second switching element, 100 ... base material, 116 ... ink chamber, 117 ... wall material, 118 ... piezoelectric member, 119 ... insulating coating, 131 ... first groove, 132 ... second groove, 133 ... Side wall, 134 ... 1st electrode, 135 ... 2nd electrode, 136 ... 1st wiring, 137 ... 2nd wiring, 138 ... side surface, 139 ... bottom surface, 140 ... side surface, 141 ... bottom surface, 200 ... frame member, 300 ... nozzle Plate, 301 ... nozzle, 302 ... surface, 400 ... housing.

Claims (5)

A piezoelectric member having a plurality of first grooves and a plurality of second grooves alternately provided on the surface thereof, each of which is composed of a pair of side surfaces and a bottom surface.
A nozzle plate that closes the surface of the piezoelectric member in which the nozzle is arranged at least according to the position of the first groove, and
An ink chamber that communicates ink to the first groove and
A first electrode provided on at least one of the pair of side surfaces of each first groove,
A second electrode provided on the side surface facing the first electrode with the piezoelectric member of each second groove formed as a gap through which the ink does not flow into .
A plurality of first drivers provided for each of the first electrodes and inputting a common waveform of the first electrode to each of the first electrodes, and a second electrode provided for each of the second electrodes and corresponding to print data. A drive circuit having a plurality of second drivers for inputting a waveform to each of the second electrodes .
An inkjet head equipped with. The first electrode is formed over a pair of side surfaces constituting the first groove.
The inkjet head according to claim 1, wherein the second electrode is formed on the side surface facing the first electrode with the piezoelectric member of the pair of the second grooves adjacent to the first groove interposed therebetween. The plurality of second drivers of the drive circuit are each formed on the side surface of the first electrode facing the first electrode with the piezoelectric member of the pair of the second grooves adjacent to the first groove interposed therebetween. The inkjet head according to claim 2, wherein the waveform of the second electrode at which the two electrodes have the same potential is input to the second electrode . The drive circuit inputs a channel control signal for controlling whether the plurality of second drivers are turned on or off to the plurality of second drivers.
The inkjet head according to claim 3, wherein the plurality of second drivers input the waveform of the second electrode to the second electrode when the second driver is turned on by the channel control signal. The inkjet head according to any one of claims 1 to 4.
A transport device that transports the recording paper to a position facing the nozzle,
An inkjet recording device comprising.