JP2009214521A - Liquid jet apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet apparatus which avoids an increase of a parts count and a power consumption, secures jetting of a liquid to a predetermined position, and moreover enables shortening of a printing necessary time. <P>SOLUTION: A plurality of liquid jet heads 2 are arranged. In jetting the liquid from a nozzle towards a printing medium 1 by driving a nozzle actuator 22 of each liquid jet head 2 by a drive signal COM, a driving circuit is prepared in each of the liquid jet heads 2. The liquid jet apparatus is equipped with a first air conveyance path 39 which sends an external air to the driving circuit of each liquid jet head 2, a second air conveyance path 41 which cools the driving circuit and sends the air heated through the heat exchange to a printing surface of the printing medium 1 on the downstream side in a conveyance direction of the printing medium from the liquid jet head 2, and a third air conveyance path 43 which discharges outside the air that flows along the printing surface of the printing medium 1 jetted with the liquid. Hence the driving circuit is cooled efficiently, and also drying of the liquid jetted to the printing surface of the printing medium 1 is promoted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus configured to print predetermined characters, images, and the like by ejecting minute liquid from a plurality of nozzles and forming fine particles (dots) on a print medium. .

A liquid jet printing apparatus, which is one of such liquid jet apparatuses, is generally inexpensive and can easily obtain high-quality color prints. Therefore, along with the widespread use of personal computers and digital cameras, not only offices. It is also widely used by general users.
Among such liquid ejecting printing apparatuses, those that place a liquid ejecting head in which liquid ejecting nozzles are formed on a moving body called a carriage and move in a direction crossing the transport direction of the print medium are generally referred to as “multi-pass printing”. Called "device". On the other hand, what is capable of printing in a so-called one pass by arranging a long liquid jet head in a direction crossing the conveyance direction of the printing medium is generally called a “line head type printing apparatus”. When configuring a line head type liquid ejecting head, for example, as described in Patent Document 1 below, a block-shaped liquid ejecting head in which a plurality of nozzles are formed in a row intersects the print medium conveyance direction. In some cases, a line head type liquid ejecting head is configured by arranging a plurality of liquid jet heads in the direction.

By the way, especially in the line head type liquid jet printing apparatus, it is desired to shorten the drying time of the liquid ejected onto the printing surface of the transported print medium. In order to meet the demand, for example, in Patent Document 1 below, air heated by a heating means such as a far-infrared lamp is supplied to the printing surface of the printing medium on which the liquid is jetted to promote drying of the liquid. is doing. In Patent Document 2 below, air is supplied from the outside to the heat generating circuit unit to cool the circuit unit and heat the air by heat exchange, and the heated air is supplied from the vicinity of the nozzle of the liquid ejecting head to the liquid. The drying of the liquid is promoted by blowing in the jetting direction and jetting heated air simultaneously with the liquid onto the printing surface of the print medium.
JP 2007-62115 A Japanese Patent Laid-Open No. 2-252566

However, since the heating means such as a far-infrared lamp is individually required as in Patent Document 1, there is a problem that the number of parts and power consumption increase. Further, when the heated air is ejected from the vicinity of the nozzles of the liquid ejecting head to the printing surface of the print medium, a vortex is generated and the liquid ejecting direction is disturbed, so that the liquid cannot be ejected to a predetermined position. There is a problem.
The present invention has been developed by paying attention to these problems, avoiding an increase in the number of parts and power consumption, ensuring liquid ejection to a predetermined position, and further reducing the time required for printing. An object of the present invention is to provide a liquid ejecting apparatus.

  In order to solve the above problems, the liquid ejecting apparatus of the invention applies a plurality of nozzles provided in a liquid ejecting head, a nozzle actuator provided corresponding to the nozzle, and a drive signal to the nozzle actuator. A liquid ejecting apparatus including a drive circuit and a transport belt for transporting a print medium, wherein a plurality of the liquid ejecting heads are provided, and the driving circuit is provided in each of the liquid ejecting heads. The first air conveyance path for supplying external air to the air and the drive circuit are cooled, and the air heated by the heat exchange is sent to the print surface of the print medium downstream from the liquid ejecting head in the print medium conveyance direction. And a third air conveyance path for discharging the air flowing along the printing surface of the print medium to the outside.

  Thus, according to the liquid ejecting apparatus of the present invention, the drive circuit provided in the liquid ejecting head is efficiently cooled, and the liquid ejected onto the printing surface of the print medium by the air heated by the heat exchange is cooled. The drying can be accelerated and air that may be mixed with liquid mist can be discharged to the outside, so that the increase in the number of parts and power consumption can be avoided, and the liquid can be injected to a predetermined position. By shortening the line, the time required from the output of the drive signal to the liquid ejection can be shortened, and the time required for printing itself can be shortened.

In the liquid ejecting apparatus according to the aspect of the invention, the third air transport path may be an air suction port for sucking air flowing along the print surface of the print medium on the downstream side in the print medium transport direction from the liquid ejecting head. Is provided on both sides in the width direction of the conveyor belt.
According to the liquid ejecting apparatus of the present invention, it is possible to prevent the air fed from the second air conveyance path to the printing surface of the print medium from flowing in the direction of the liquid ejecting head, and thereby to the predetermined position. Liquid injection can be ensured.

Further, the liquid ejecting apparatus of the present invention dries the liquid ejected on the printing surface of the print medium by the radiant heat of the supplied air between the second air transport path and the third air transport path. The heat-dissipation duct is provided.
According to the liquid ejecting apparatus of the present invention, it is possible to prevent the air supplied from the second air conveyance path from flowing in the direction of the liquid ejecting head, thereby ensuring the ejection of the liquid to a predetermined position. it can.

In the liquid ejecting apparatus according to the aspect of the invention, a suction port for external air to the first air transfer path and a discharge port for air discharged from the third air transfer path may be in different directions. Is.
According to the liquid ejecting apparatus of the present invention, as a result of being fed to the printing surface of the printing medium, the warm air discharged from the third air transport path and possibly mixed with liquid mist is transported by the first air transport. Inhalation into the route can be suppressed and prevented.

Further, the liquid ejecting apparatus of the invention is characterized in that the drive circuit is hermetically covered with a circuit case made of a material having low thermal conductivity, and air ports are provided in at least two places of the circuit case. .
According to the liquid ejecting apparatus of the present invention, if the air is introduced from one of the air ports of each circuit case and the air is discharged from the remaining air ports, the drive circuit in the circuit case is efficiently cooled. Therefore, energy loss can be reduced, and the sprayed liquid mist can be prevented from being scattered and penetrating into the drive circuit.

In the liquid ejecting apparatus according to the aspect of the invention, the circuit case may be fixedly supported on the casing of the liquid ejecting head itself by a connecting member made of a material having low thermal conductivity.
According to the liquid ejecting apparatus of the invention, the heat conduction from the drive circuit in the circuit case to the casing of the liquid ejecting head itself is suppressed and the temperature change of the liquid ejecting head is suppressed and the liquid ejecting characteristics change. Can be suppressed.
The liquid ejecting apparatus of the present invention is characterized in that air from the outside is introduced into one of the air ports of the circuit case, and air is discharged from the other air port to the outside.
According to the liquid ejecting apparatus of the present invention, the drive circuit in the circuit case can be efficiently cooled.

Next, a first embodiment of the liquid ejecting apparatus of the invention will be described using an ink jet printing apparatus.
FIG. 1 is a schematic configuration diagram of a printing apparatus according to the present embodiment, in which the print medium 1 is conveyed in the direction of the arrow from the right to the left in the figure, and is printed in a print area in the middle of the conveyance. It is a line head type printing apparatus.

  Reference numeral 2 in FIG. 1 denotes a plurality of liquid ejecting heads provided above the conveyance line of the print medium 1, which are arranged side by side in a direction crossing the print medium conveyance direction and fixed to the head fixing plate 11. Has been. The head fixing plate 11 is sized so as to divide the entire casing of the printing apparatus above the conveyance line of the print medium 1, and is formed with a recessed portion through which only the lower end portion of the liquid ejecting head 2 is inserted. The lower end of the head 2 is fixed so as to be inserted. A large number of nozzles are formed on the lowermost surface of each liquid jet head 2, and this surface is called a nozzle surface. The nozzles are generally arranged in a row in a direction intersecting the print medium conveyance direction for each color of liquid to be ejected, and the row is referred to as a nozzle row, or the row direction is referred to as a nozzle row direction. I call you. A line head that extends over the entire length in the direction intersecting the transport direction of the print medium 1 is formed by the nozzle rows of all the liquid jet heads 2 arranged in the direction intersecting the print medium transport direction. When the print medium 1 passes below the nozzle surfaces of these liquid ejecting heads 2, printing is performed by ejecting liquid from a large number of nozzles formed on the nozzle surfaces.

  For example, liquids such as yellow (Y), magenta (M), cyan (C), and black (K) inks are supplied to the liquid ejecting head 2 from liquid tanks of respective colors (not shown) through liquid supply tubes. Supplied. Then, a small amount of liquid dots are formed on the print medium 1 by simultaneously ejecting a necessary amount of liquid from a nozzle formed in each liquid ejecting head 2 to a necessary portion. By performing this for each color, it is possible to perform printing by so-called one-pass only by passing the print medium 1 conveyed by the conveyance unit 4 once.

  As a method of ejecting liquid from each nozzle of the liquid ejecting head, there are an electrostatic method, a piezo method, a film boiling liquid ejecting method, and the like. In this embodiment, the piezo method is used. In the piezo method, when a drive signal is given to a piezoelectric element that is a nozzle actuator, the diaphragm in the cavity is displaced to cause a pressure change in the cavity, and a droplet is ejected from the nozzle by the pressure change. . The droplet ejection amount can be adjusted by adjusting the peak value of the drive signal and the voltage increase / decrease slope. Note that the piezoelectric element used in the piezo method is a capacitive load. Further, the present invention can be similarly applied to a liquid ejecting method other than the piezo method.

  Below the liquid jet head 2, a transport unit 4 for transporting the print medium 1 in the transport direction is provided. The conveying unit 4 is configured by winding a conveying belt 6 around a driving roller 8 and a driven roller 9, and an electric motor (not shown) is connected to the driving roller 8. An adsorption device (not shown) for adsorbing the print medium 1 to the surface of the conveyance belt 6 is provided inside the conveyance belt 6. As this adsorption device, for example, an air suction device that adsorbs the print medium 1 to the conveyance belt 6 by negative pressure, an electrostatic adsorption device that adsorbs the print medium 1 to the conveyance belt 6 by electrostatic force, or the like is used. Accordingly, when only one sheet of the printing medium 1 is fed from the sheet feeding unit 3 on the right side of the drawing onto the conveying belt 6 and the driving roller 8 is rotationally driven by the electric motor, the conveying belt 6 is rotated in the conveying direction of the printing medium, The printing medium 1 is sucked and transported to the transport belt 6 by the suction device. While the printing medium 1 is being conveyed, printing is performed by ejecting liquid from the liquid ejecting head 2. The print medium 1 that has finished printing is discharged to the downstream side in the transport direction, that is, to the left discharge portion in the drawing.

  A control device for controlling itself is provided in the printing apparatus. For example, as shown in FIG. 2, the control device prints on a print medium by controlling a printing device, a paper feeding device, and the like based on print data input from a host computer 60 such as a personal computer or a digital camera. The processing is performed. An input interface 61 for reading print data input from the host computer 60 and detection data detected by various sensors (not shown), and arithmetic processing such as print processing based on the print data input from the input interface 61 are performed. A control unit 62 configured by, for example, a microcomputer to be executed, a paper feed roller motor driver 63 for controlling the drive of the paper feed roller motor 17 connected to the paper feed roller in the paper feed unit 3, and two later-described two A suction fan motor driver 64i and a discharge fan motor driver 64o for driving and controlling one suction fan motor 18i and two discharge fan motors 18o connected to the fan, and a head driver 65 for driving and controlling each liquid ejecting head 2. An electric motor 7 connected to the drive roller 8 An electric motor driver 66 for turning control, the driver 63,65,66 and outside of the sheet feeding roller motor 17, the liquid jet heads 2 and 3, and includes an interface 67 for connecting the electric motor 7.

  The control unit 62 temporarily stores a CPU (Central Processing Unit) 62a that executes various processes such as a print process, and print data input through the input interface 61 or various data when the print data print process is executed. A random access memory (RAM) 62c that temporarily stores a program such as a print process or a nonvolatile semiconductor memory that stores a control program executed by the CPU 62a. ) 62d. When the control unit 62 obtains print data (image data) from the host computer 60 via the interface 61, the CPU 62a executes a predetermined process on the print data to determine which nozzle of any liquid ejecting head 2. Liquid ejection head selection data and nozzle selection data (driving signal selection data) on whether or not how much liquid is ejected are calculated from the print data, liquid ejection head selection data, driving signal selection data, and Based on input data from various sensors, a control signal is output to each driver 63, 65, 66. A drive signal for driving the actuator is output from each driver 63, 65, 66, and the paper feed roller motor 17 and the electric motor 7 are operated to feed, convey and discharge the print medium 1, and print. A printing process on the medium 1 is executed. In the present embodiment, as will be described later, since a drive circuit is mounted on each liquid ejecting head 2, only a control signal is output from each head driver 65 to each liquid ejecting head 2. Each component in the control unit 62 is electrically connected through a bus (not shown).

  FIG. 3 shows a specific configuration of the drive circuit mounted on each liquid jet head 2. When the drive circuit is mounted on the liquid ejecting head 2, the signal line of the drive signal for driving the nozzle actuator is shortened, and the loss can be reduced and the response of the nozzle actuator can be improved. The time can be shortened. The drive circuit of the present embodiment includes a control circuit 23 that is configured by a microcomputer or the like and performs an original calculation process, a drive waveform data for generating and outputting a drive signal, and a memory 24 that stores programming of the calculation process. Based on the drive waveform data, a drive waveform signal generation circuit 25 that generates a drive waveform signal WCOM that serves as a reference of a signal that controls the drive of the nozzle actuator 22 based on the drive signal, and the drive waveform signal generation circuit 25 generates the drive waveform signal. A modulation circuit 26 that performs pulse modulation on the drive waveform signal WCOM, a digital power amplifier that power-amplifies the modulation signal pulse-modulated by the modulation circuit 26, a so-called class D amplifier 28, and power amplification obtained by power amplification by the digital power amplifier 28. The modulation signal is smoothed, and the drive signal COM (drive pulse PCOM) is output from the selection switch 201. Configured with a smoothing filter 29 to be supplied to the nozzle actuator 22. Further, this drive circuit is provided with control signal connection portions 13i, 13o for inputting / outputting control signals from the control device of FIG. 2 and power connection portions 14i, 14o for inputting / outputting nozzle actuator driving power. ing.

  The control circuit 23 reads out the digital drive waveform data stored in the memory 24, outputs the digital drive waveform data to the drive waveform signal generation circuit 25 at a predetermined sampling period, and performs on / off control of the selection switch 201 composed of a transmission gate. . The drive waveform signal generation circuit 25 converts the drive waveform data output from the control circuit 23 into a voltage signal and holds it for a predetermined sampling period, and converts it into an analog signal by a D / A converter to obtain a drive waveform signal WCOM. Output. In the present embodiment, a general pulse width modulation (PWM) circuit is used as the modulation circuit 26 that performs pulse modulation on the drive waveform signal WCOM. As is well known, in the pulse width modulation, a triangular wave signal having a predetermined frequency is generated by a triangular wave signal generating circuit, and this triangular wave signal and the drive waveform signal WCOM are compared by a comparator. For example, the drive waveform signal WCOM is larger than the triangular wave signal. A pulse signal that is sometimes on-duty is output as a modulation signal. The digital power amplifier 28 substantially includes a half-bridge class D output stage 21 composed of a high-side switching element Q1 and a low-side switching element Q2 for amplifying power, and a modulation signal from the modulation circuit 26. And a gate driving circuit 30 for adjusting the gate-source signals GH and GL of the switching elements Q1 and Q2. Further, the smoothing filter 29 is constituted by, for example, a low-pass filter (low-pass filter) comprising a combination of a coil and a capacitor, and this low-pass filter removes the modulation period component of the power amplification modulation signal, in this case, the frequency component of the triangular wave signal. The

  In the digital power amplifier 28, when the modulation signal is at the Hi level, the gate-source signal GH of the high-side switching element Q1 is at the Hi level, and the gate-source signal GL of the low-side switching element Q2 is at the Lo level. Therefore, the high-side switching element Q1 is turned on and the low-side switching element Q2 is turned off. As a result, the output of the half-bridge class D output stage 21 is the supply power VDD. On the other hand, when the modulation signal is at the Lo level, the gate-source signal GH of the high-side switching element Q1 is at the Lo level, and the gate-source signal GL of the low-side switching element Q2 is at the Hi level. The side switching element Q1 is turned off and the low side switching element Q2 is turned on. As a result, the output of the half-bridge output stage 21 becomes zero.

  In this way, when the high-side and low-side switching elements are digitally driven, a current flows through the ON-state switching elements, but the resistance value between the drain and source is very small and almost no loss occurs. In addition, since no current flows through the switching element in the OFF state, no loss occurs. Therefore, the loss of the digital power amplifier 28 is extremely small, and a switching element such as a small MOSFET can be used. In the liquid ejecting apparatus of the present embodiment, an analog power amplifier can be used instead of the digital power amplifier.

  FIG. 4 shows an example of a drive signal COM that is supplied from the control device of the printing apparatus of the present embodiment to the liquid ejecting head 2 and drives a nozzle actuator made of a piezoelectric element. In the present embodiment, a signal whose potential changes around an intermediate potential is used. This drive signal COM is a time series connection of drive pulses PCOM as unit drive signals for driving the nozzle actuator to eject liquid, and the rising portion of each drive pulse PCOM communicates with the nozzle (pressure). The volume of the chamber is expanded and the liquid is drawn in (it can be said that the meniscus is drawn in considering the liquid ejection surface), and the falling portion of the drive pulse PCOM reduces the cavity volume and pushes out the liquid (liquid In this stage, it can be said that the meniscus is extruded), and as a result of extruding the liquid, droplets are ejected from the nozzle.

  By variously changing the voltage increase / decrease slope and peak value of the driving pulse PCOM composed of this voltage trapezoidal wave, the liquid drawing amount and drawing speed, the liquid pushing amount and the pushing speed can be changed. It is possible to obtain dots of different sizes by changing the amount of injection. Therefore, even when a plurality of drive pulses PCOM are connected in time series, a single drive pulse PCOM is selected and supplied to the actuator, and droplets are ejected or a plurality of drive pulses PCOM are selected and the actuator is selected. In this way, dots of various sizes can be obtained by ejecting droplets a plurality of times. That is, if a plurality of droplets land on the same position before the liquid dries, it is substantially the same as ejecting a large droplet, and the size of the dot can be increased. By combining such techniques, it is possible to increase the number of gradations. The mechanism for selecting the drive signal by the drive signal selection data SI & SP can be realized in the form described in, for example, Japanese Patent Application Laid-Open No. 2003-1824. Note that the driving pulse PCOM1 at the left end in FIG. This is called microvibration, and is used, for example, to suppress or prevent thickening of the nozzle without ejecting droplets.

  A drive signal for selecting a nozzle to be ejected based on print data as a control signal from the control device of FIG. 2 and determining a connection timing to a drive signal COM of a nozzle actuator such as a piezoelectric element, etc. After the selection data SI & SP and nozzle selection data are input to all nozzles, the latch signal LAT, channel signal CH, and drive signal selection for connecting the drive signal COM and the nozzle actuator of the liquid jet head 2 based on the drive signal selection data SI & SP A clock signal SCK for transmitting the data SI & SP as a serial signal to the liquid jet head 2 is input. Hereinafter, the minimum unit of the drive signal for driving the nozzle actuator is referred to as a drive pulse PCOM, and the entire signal in which the drive pulses PCOM are connected in time series is referred to as a drive signal COM. That is, a series of drive signals COM starts to be output in response to the latch signal LAT, and a drive pulse PCOM is output for each channel signal CH.

  FIG. 5 shows a specific configuration of the switching controller constructed in the control circuit 23 in order to supply the drive signal COM (drive pulse PCOM) to the nozzle actuator 22. This switching controller temporarily stores the shift register 211 that stores drive signal selection data SI & SP for designating the nozzle actuator 22 such as a piezoelectric element corresponding to the nozzle that should eject liquid, and the data of the shift register 211. The level shifter 213 is configured to connect the drive signal COM to the nozzle actuator 22 such as a piezo element by converting the level of the output of the latch circuit 212 and the output of the latch circuit 212 to the selection switch 201.

  The drive signal selection data signal SI & SP is sequentially input to the shift register 211, and the storage area is sequentially shifted from the first stage to the subsequent stage in accordance with the input pulse of the clock signal SCK. The latch circuit 212 latches each output signal of the shift register 211 by the input latch signal LAT after the drive signal selection data SI & SP for the number of nozzles is stored in the shift register 211. The signal stored in the latch circuit 212 is converted by the level shifter 213 to a voltage level at which the selection switch 201 at the next stage can be turned on / off. This is because the drive signal COM is higher than the output voltage of the latch circuit 212, and the operating voltage range of the selection switch 201 is set higher accordingly. Accordingly, a nozzle actuator such as a piezoelectric element whose selection switch 201 is closed by the level shifter 213 is connected to the drive signal COM (drive pulse PCOM) at the connection timing of the drive signal selection data SI & SP. In addition, after the drive signal selection data SI & SP of the shift register 211 is stored in the latch circuit 212, the next print information is input to the shift register 211, and the stored data in the latch circuit 212 is sequentially updated in accordance with the liquid ejection timing. . In addition, the code | symbol HGND in a figure is a ground end of nozzle actuators, such as a piezoelectric element. Further, according to the selection switch 201, even after the nozzle actuator such as a piezoelectric element is disconnected from the drive signal COM (drive pulse PCOM), the input voltage of the nozzle actuator 22 is maintained at the voltage just before the disconnection.

  In such a drive circuit, for example, although the loss is reduced by using the digital power amplifier described above, heat generation itself cannot be avoided. On the other hand, when the temperature of the liquid ejecting head 2 changes due to heat generation, the nozzle diameter and the liquid viscosity change and the liquid ejecting characteristics change. Therefore, it is necessary to prevent the heat of the drive circuit from being conducted to the liquid ejecting head. Therefore, in the present embodiment, the drive circuit is hermetically sealed with the circuit case 31 having a low thermal conductivity. FIG. 6 shows details of the liquid ejecting head 2 and the circuit case 31. The circuit case 31 is preferably made of polyester or polypropylene resin, desirably a ceramic material. The circuit case 31 is fixedly supported on the casing of the liquid jet head 2 itself by a connecting member 32 having a low thermal conductivity. The contact area between the connecting member 32 and the circuit case 31 or the casing of the liquid jet head 2 is reduced to reduce heat conduction from the circuit case 31. Incidentally, reference numeral 33 in the figure denotes the liquid inlet described above. The liquid is ejected from the nozzle surface which is the lowermost surface in FIG.

  In addition, air ports 34 and 35 communicating with a drive circuit housed therein are provided in the lower and upper portions of the circuit case 31, and of these, the air ports 34 provided in the lower portion of the circuit case 31 are introduced. The air opening 35 provided in the upper part of the air opening and the circuit case 31 is a discharge air opening. FIG. 7 shows an example in which the introduction air port 34 and the discharge air port 35 of the circuit case 31 connected to each of the plurality of liquid jet heads 2 are connected to different portions outside the apparatus. This connection form is a plan view of the device, and the suction port 36 opens to the outside of the device on the left side of the drawing, and a suction fan 38i is provided in the suction port 36, and the suction fan motor 18i is connected to the suction fan 38i. It is connected. A series of first air conveyance paths 39 made of a material having a low thermal conductivity is provided from the suction port 36, and a branch portion 40 also made of a material having a low thermal conductivity is provided in the first air conveyance path 39. Thus, the introduction air port 34 of each circuit case 31 is connected, and external air is introduced into each circuit case 31. Further, the exhaust air port 35 of each circuit case 31 is connected to a series of second air conveyance paths 41 via a branch portion (not shown), whereby the air introduced into each circuit case 31 from the introduction air port 34. Is configured to cool the drive circuit in the copper circuit case 31 and supply the air heated by the heat exchange to the second air conveyance path 49. In addition, it is preferable to comprise the 1st air conveyance path | route 39, the branch part 40, and the 2nd air conveyance path | route 41 with a material with low heat conductivity, and resin pipes etc. are mentioned as such a material.

  As shown in FIG. 8 or FIG. 1, the second air transport path 41 is an opening provided in the fixed plate 11 at the center in the width direction of the transport belt 6 and downstream of the liquid ejection head 2 in the print medium transport direction. The heated air is fed to the printing surface of the printing medium 1 that is communicated with the unit 42 and is sucked and conveyed by the conveying belt 6, that is, the surface on which the liquid is ejected from the liquid ejecting head 2. Further, third air conveyance paths 43 are provided on both sides in the width direction of the conveyance belt 6 at the position where the opening 42 of the fixed plate 11 is provided, and one end is provided on both sides of the print medium conveyance line. The air suction port 44 is opened, and the other end communicates with a discharge port 37 opened in the casing of the printing apparatus. A discharge fan 38o is provided in the discharge port 37, and the discharge fan 38o A discharge fan motor 18o is connected. Incidentally, as shown in FIG. 8 or FIG. 1, the suction port 36 and the discharge port 37 have different orientations opened in the casing of the printing apparatus. Further, by making the exhaust air flow rate by the two exhaust fans 38o larger than the intake air flow rate by the one intake fan 38i, the reverse flow of the flow of the external air sucked by the suction fan 38i to the exhaust fan 38o is prevented. .

  Therefore, the drive circuit is cooled, and as a result, the air heated by the heat exchange is fed from the second air conveyance path 41 to the printing surface of the print medium 1, that is, the surface on which the liquid is ejected by the liquid ejecting head 2. It is sprayed from the opening 42 onto the printing surface of the print medium 1. Drying of the liquid sprayed on the printing surface of the print medium 1 is promoted by the sprayed heated air. Air thus blown onto the printing surface of the print medium 1 and flowing along the printing surface is sucked into the third air conveyance path 43 from the air suction port 44 and discharged from the discharge port 37 to the outside of the casing of the printing apparatus. Is done. By this air flow, it is possible to suppress and prevent the air blown to the printing surface of the print medium 1 from flowing toward the liquid ejecting head 2, thereby allowing the liquid ejected from the liquid ejecting head 2 to flow out of the print medium 1. It can be landed at a predetermined position. Further, when liquid is ejected from the liquid ejecting head 2, a liquid mist is generated around the liquid jet head 2, and this liquid mist can also be discharged from the third air conveyance path 43 to the outside of the printing apparatus.

  In addition, the connection method of each air conveyance path | route is not restricted above, For example, you may connect like FIG. In this connection method, a suction port 36 is opened in the casing of the printing apparatus at the lower side of the drawing, that is, upstream of the print medium transport direction, and a series of first air transport paths 39 are connected to the suction port 36, and the first The introduction air ports 34 of the circuit cases 31 of the plurality of liquid jet heads 2 are connected from the air conveyance path 39 via the branching portion 40. On the other hand, the second air conveyance path 41 is individually connected to the discharge air port 35 of each circuit case 31, arranged toward the downstream side in the print medium conveyance direction, and the tip thereof is connected to the communication part 45. The communication part 45 communicates with the opening 42 of the fixed plate 11. By such an air conveyance path connection method, for example, maintenance of each liquid ejecting head 2 is facilitated.

  As described above, according to the liquid ejecting apparatus of the present embodiment, the plurality of nozzles provided in the liquid ejecting head 2, the nozzle actuator 22 provided corresponding to the nozzle, and the drive signal COM are applied to the nozzle actuator 22. A liquid ejecting apparatus including a drive circuit, a transport belt for transporting a print medium 1, and a plurality of liquid ejecting heads 2 are provided, and each of the liquid ejecting heads 2 is provided with a drive circuit and driven. The first air conveyance path 39 for supplying external air to the circuit and the drive surface of the print medium 1 are cooled on the downstream side of the liquid ejection head 2 in the print medium conveyance direction. Provided in the liquid ejecting head 2 by including the second air conveyance path 41 for feeding the air and the third air conveyance path 43 for discharging the air flowing along the printing surface of the print medium 1 to the outside. The drive circuit is efficiently cooled, the air heated by the heat exchange accelerates the drying of the liquid jetted onto the printing surface of the print medium 1, and the air that may be mixed with the liquid mist is discharged to the outside. As a result, the increase in the number of parts and power consumption can be avoided, the liquid can be ejected to a predetermined position, and the time required from the output of the drive signal to the liquid ejection can be shortened by shortening the signal line. The printing time itself can be shortened.

Further, the third air conveyance path 43 has an air suction port 44 for sucking air flowing along the printing surface of the print medium 1 on the downstream side in the print medium conveyance direction from the liquid ejecting head 2, and the width of the conveyance belt 6. By providing on both sides in the direction, it is possible to prevent the air fed from the second air conveyance path 41 to the printing surface of the printing medium 1 from flowing in the direction of the liquid ejecting head 2, and thereby to a predetermined position. The liquid injection can be ensured.
Further, the external air intake port 36 to the first air transport path 39 and the air exhaust port 37 discharged from the third air transport path 43 are oriented in different directions, so that they are sent to the printing surface of the print medium 1. As a result, it is possible to prevent the warm air discharged from the third air conveyance path 43 from being mixed with the liquid mist from being sucked into the first air conveyance path 39.

Further, the drive circuit is hermetically covered with a circuit case 31 made of a material having low thermal conductivity, and air ports 34 and 35 are provided in at least two places of the circuit case 31, so that the introduction air ports 34 of each circuit case 31 are provided. If air is introduced and air is exhausted from the exhaust air port 35, the drive circuit in the circuit case 31 can be efficiently cooled, so that energy loss can be reduced and injected. It is possible to prevent the liquid mist from scattering and floating and entering the drive circuit.
In addition, the circuit case 31 is fixedly supported on the housing of the liquid ejecting head 2 itself by a material having low thermal conductivity or a runoff coupling member 32, so that the liquid ejecting head 2 itself is driven from the drive circuit in the circuit case 31. It is possible to suppress and prevent the temperature change of the liquid ejecting head 2 by suppressing and suppressing the heat conduction to the housing, thereby suppressing the change of the liquid ejecting characteristics.
Further, by introducing air from the outside to the introduction air port 34 of the circuit case 31 and exhausting the air from the discharge air port 35 to the outside, the drive circuit in the circuit case 31 can be efficiently cooled.

  Next, a second embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIG. The schematic configuration of the liquid ejecting apparatus of the present embodiment is substantially the same as that of FIG. 8 of the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. In the present embodiment, a heat radiation duct 46 is disposed between the opening 42 of the second air conveyance path 41 and the third air conveyance path 43. The heat radiating duct 46 communicates the second air conveyance path 41 and the third air conveyance path 43 in an airtight manner, and spreads above the printing surface of the print medium 1 that is adsorbed and conveyed by the conveyance belt 6. It consists of a square airtight box. The heat radiating duct is made of a material having high thermal conductivity such as a metal material such as copper. Therefore, the drive circuit is cooled, and as a result, the air heated by the heat exchange is fed into the heat radiating duct 46 from the second air conveyance path 41, and the heat radiating duct 46 itself is heated by the thermal energy. As a result, radiant heat is radiated from the heat radiating duct 46, and drying of the liquid jetted onto the printing surface of the print medium 1 is promoted by the radiant heat. The air that has contributed to the drying of the liquid is discharged from the discharge port 37 to the outside of the apparatus casing via the third air conveyance path 43 without leaking into the casing of the printing apparatus. Accordingly, there is no influence on the flying of the liquid ejected from the liquid ejecting head 2.

As described above, according to the liquid ejecting apparatus of the present embodiment, in addition to the effects of the first embodiment, the radiant heat of the air supplied between the second air transport path 41 and the third air transport path 43 is used. By providing the heat radiating duct 46 for drying the liquid jetted on the printing surface of the print medium 1, it is possible to prevent the air supplied from the second air transport path 41 from flowing in the direction of the liquid jet head 2. As a result, it is possible to ensure the ejection of the liquid to a predetermined position.
In the above-described embodiment, only the case where the liquid ejecting apparatus of the present invention is used in a line head type printing apparatus has been described in detail. However, the liquid ejecting apparatus of the present invention can be similarly applied to a multi-pass type printing apparatus. is there.

  In the above embodiment, the liquid ejecting apparatus of the present invention is embodied in an ink jet printing apparatus. However, the present invention is not limited to this, and liquids other than ink (functional material particles are dispersed in addition to liquids). It is also possible to embody the present invention in a liquid ejecting apparatus that ejects or ejects a fluid other than a liquid (including a fluid such as a liquid or gel) or a fluid other than a liquid (such as a solid that can be ejected by flowing as a fluid). For example, a liquid material ejecting apparatus that ejects a liquid material that contains materials such as electrode materials and color materials used in the manufacture of liquid crystal displays, EL (electroluminescence) displays, surface-emitting displays, color filters, and the like in a dispersed or dissolved form. Further, it may be a liquid ejecting apparatus that ejects a bio-organic matter used for biochip manufacturing, or a liquid ejecting apparatus that ejects a liquid that is used as a precision pipette and serves as a sample. In addition, transparent resin liquids such as UV curable resins for forming liquid injection devices that inject lubricating oil onto precision machines such as watches and cameras, micro hemispherical lenses (optical lenses) used in optical communication elements, etc. Examples include a liquid ejecting apparatus that ejects a liquid onto a substrate, a liquid ejecting apparatus that ejects an etching solution such as acid or alkali to etch the substrate, a fluid ejecting apparatus that ejects a gel, and a powder such as toner. It may be a fluid ejection recording apparatus that ejects a solid. The present invention can be applied to any one of these injection devices.

1 is a front view of a schematic configuration showing a first embodiment of a printing apparatus using a liquid ejecting apparatus of the invention. FIG. 2 is a block diagram of a control device of the liquid jet printing apparatus of FIG. 1. 3 is a block diagram of a drive circuit provided in each liquid ejecting head. FIG. FIG. 6 is an explanatory diagram of a drive signal for driving a nozzle actuator in each liquid ejecting head. It is a block diagram of a switching controller. It is a detailed explanatory diagram of a liquid jet head and a circuit case. It is explanatory drawing of an example which connects the introduction air port and discharge air port of a circuit case to a 1st air conveyance path | route and a 2nd air conveyance path | route. FIG. 2 is a schematic configuration side view of the printing apparatus of FIG. 1. It is explanatory drawing of the other example which connects the introduction air port and discharge air port of a circuit case to a 1st air conveyance path | route and a 2nd air conveyance path | route. FIG. 6 is a schematic configuration side view illustrating a second embodiment of a printing apparatus using the liquid ejecting apparatus of the invention.

Explanation of symbols

  1 is a print medium, 2 is a liquid ejecting head, 3 is a paper feed unit, 4 is a transport unit, 5 is a paper feed roller, 6 is a transport belt, 7 is an electric motor, 8 is a drive roller, 9 is a driven roller, 10 is A paper discharge unit, 11 is a fixed plate, 12 is a slide switch, 13i and 13o are control signal connection units, 14i and 14o are power connection units, 18i and 18o are fan motors, 21 is a half-bridge class D output stage, 22 Is a nozzle actuator, 23 is a control circuit, 24 is a memory, 25 is a drive waveform signal generation circuit, 26 is a modulation circuit, 28 is a digital power amplifier, 29 is a smoothing filter, 30 is a gate drive circuit, 31 is a circuit case, 32 is The connecting member, 34 is an introduction air port, 35 is a discharge air port, 36 is a suction port, 37 is a discharge port, 38i and 38o are fans, 39 is a first air conveyance path, 40 is a branching portion, and 41 is a second air. Feed path 42 is opening, the third air transport path 43, 44 is an air inlet, 46 radiator duct 62 control unit, 64i, 64o fan motor driver, 65 denotes a head driver

Claims (7)

A plurality of nozzles provided in the liquid jet head;
A nozzle actuator provided corresponding to the nozzle;
A drive circuit for applying a drive signal to the nozzle actuator;
A transport belt for transporting print media;
A liquid ejecting apparatus comprising:
A plurality of the liquid ejecting heads, and the drive circuit is provided for each of the liquid ejecting heads;
A first air conveyance path for supplying external air to the drive circuit;
A second air conveyance path that cools the drive circuit and supplies air heated by the heat exchange to the print surface of the print medium downstream of the liquid jet head in the print medium conveyance direction;
A third air conveyance path for discharging the air flowing along the printing surface of the print medium to the outside;
A liquid ejecting apparatus comprising:   The third air conveyance path has air suction ports for sucking air flowing along the print surface of the print medium on both sides in the width direction of the conveyance belt, on the downstream side in the print medium conveyance direction from the liquid ejecting head. The liquid ejecting apparatus according to claim 1, further comprising a liquid ejecting apparatus.   A heat dissipating duct is provided between the second air transport path and the third air transport path to dry the liquid jetted onto the printing surface of the print medium by radiant heat of the air being fed. The liquid ejecting apparatus according to claim 1.   4. The external air intake port to the first air transfer path and the air discharge port discharged from the third air transfer path are set in different directions. 5. The liquid ejecting apparatus according to 1.   5. The drive circuit according to claim 1, wherein the drive circuit is hermetically covered with a circuit case made of a material having low thermal conductivity, and air ports are provided in at least two places of the circuit case. Liquid ejector.   The liquid ejecting apparatus according to claim 5, wherein the circuit case is fixedly supported on a housing of the liquid ejecting head itself by a connecting member made of a material having low thermal conductivity.   7. The liquid ejecting apparatus according to claim 5, wherein air from outside is introduced into any one air port of the circuit case, and air is discharged outside from the other air port.

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