JP7522595B2 - Inkjet head and inkjet recording device - Google Patents

Description

The present invention relates to an inkjet head and an inkjet recording device.

Inkjet recording devices eject ink from the nozzles of an inkjet head to record an image on a recording medium. The inkjet head is equipped with a piezoelectric element. Ink is ejected by deforming the piezoelectric element. Various inks are used to record images. For example, high-viscosity inks are sometimes used.

Patent Document 1 proposes an application nozzle head that uses a displacement magnification mechanism to eject highly viscous ink from the nozzle. By using the displacement magnification mechanism, the plunger can be driven at high speed with a large amount of displacement, allowing highly viscous ink to be ejected from the nozzle.

The device disclosed in Patent Document 1 includes a nozzle hole that ejects liquid material, a supply flow path that supplies liquid material to the nozzle hole, a plunger that reciprocates in contact with the liquid in the supply flow path, a displacement magnification mechanism that applies a displacement to the plunger, and an actuator that applies a displacement to the displacement magnification mechanism. The above configuration is required for each nozzle, and when considering a head with multiple nozzles, there are concerns that the number of parts will be large and the device will become large in size.

JP 2019-030865 A

The present invention aims to solve these problems and provide an inkjet head and inkjet recording device that can stably eject ink even when high-viscosity ink is used to record an image.

One aspect of the present invention is an inkjet head including a first nozzle and a second nozzle that eject ink on a first side surface, the ink chamber containing ink, a first rod that moves back and forth within the ink chamber, a second rod that moves back and forth within the ink chamber, a first piezoelectric element that moves the first rod back and forth to eject ink from the first nozzle, a second piezoelectric element that moves the second rod back and forth to eject ink from the second nozzle, a first displacement magnifying mechanism that magnifies the displacement of the first piezoelectric element, a second displacement magnifying mechanism that magnifies the displacement of the second piezoelectric element, and a top plate to which the first displacement magnifying mechanism and the second displacement magnifying mechanism are fixed on a second side opposite to the first side ,
a cooling mechanism for cooling the first piezoelectric element and the second piezoelectric element,
The cooling mechanism is characterized in that cooled air is blown onto the first piezoelectric element and the second piezoelectric element through through holes provided in the base portions of the first displacement magnifying mechanism and the second displacement magnifying mechanism.

In the inkjet head, the first displacement magnification mechanism may have a first base portion to which the first piezoelectric element is attached and a first leaf spring, and the second displacement magnification mechanism may have a second base portion to which the second piezoelectric element is attached and a second leaf spring.

In the inkjet head, the ink in the ink chamber may be pressurized.

In the inkjet head, the first nozzle, the first rod, the first piezoelectric element, and the first leaf spring may be arranged on the same axis.

Yet another aspect of the present invention is an inkjet recording device equipped with any one of the inkjet heads described above.

According to the present invention, it is possible to obtain an inkjet head and an inkjet recording device that can stably eject ink even when high viscosity ink is used to record an image.

FIG. 1 is a perspective view showing a schematic configuration of an inkjet recording apparatus. 1 is a cross-sectional view showing a schematic configuration of an inkjet head, the cutting position corresponding to line AA in FIG. 1 is a cross-sectional view showing a schematic configuration of an inkjet head, the cutting position corresponding to line BB in FIG.

The following describes an embodiment of the present invention with reference to the drawings. The present invention is not limited to the configurations described below, and various configurations can be adopted within the same technical concept. For example, some of the configurations shown below may be omitted or replaced with other configurations. Other configurations may also be included.

<Inkjet recording device>
The inkjet recording device 10 will be described with reference to FIG. 1. The inkjet recording device 10 conveys various recording media 15 and records patterns on the recording media 15. The patterns on the following parts of the recording media 15 in FIG. 1 correspond to the patterns recorded on the recording media 15. The above-mentioned parts are parts of the recording media 15 downstream of the inkjet head 30K described later in the conveying direction. The conveying direction is the direction in which the recording media 15 is conveyed by the inkjet recording device 10. Examples of the recording media 15 include building materials and fabrics. In the embodiment, a short recording medium is exemplified as the recording media 15. However, the recording medium may be long. Four colors of ink, yellow, magenta, cyan, and black, are exemplified as inks used to record the patterns. However, inks of colors different from these inks may be used to record the patterns. The number of ink colors may be three or less or five or more.

The inkjet recording device 10 includes a conveyor 20, inkjet heads 30Y, 30M, 30C, and 30K, a carriage 31, main tanks 90Y, 90M, 90C, and 90K, supply passages 91Y, 91M, 91C, and 91K, and supply valves 92Y, 92M, 92C, and 92K. The conveyor 20 conveys the recording medium 15 in the conveying direction. In the inkjet recording device 10, the conveyor 20 conveys the recording medium 15 continuously. The conveyor 20 is a belt conveyor. The conveyor 20 is similar to conveyors in known inkjet recording devices. Therefore, further explanation of the conveyor 20 will be omitted.

Inkjet head 30Y records a pattern on recording medium 15 using yellow ink. Inkjet head 30Y ejects yellow ink toward recording medium 15. Inkjet head 30M records a pattern on recording medium 15 using magenta ink. Inkjet head 30M ejects magenta ink toward recording medium 15. Inkjet head 30C records a pattern on recording medium 15 using cyan ink. Inkjet head 30C ejects cyan ink toward recording medium 15. Inkjet head 30K records a pattern on recording medium 15 using black ink. Inkjet head 30K ejects black ink toward recording medium 15. In FIG. 1, the illustration of inkjet heads 30Y, 30M, 30C, and 30K is simplified. Further explanations regarding inkjet heads 30Y, 30M, 30C, and 30K will be given later.

Inkjet heads 30Y, 30M, 30C, and 30K are mounted on the carriage 31 and aligned in the transport direction. In the inkjet recording device 10, inkjet heads 30Y, 30M, 30C, and 30K are arranged in the transport direction in the following order: inkjet head 30Y, inkjet head 30M, inkjet head 30C, and inkjet head 30K. However, the order of inkjet heads 30Y, 30M, 30C, and 30K in the transport direction may be different from the order described above. These orders are determined appropriately taking into account various conditions.

The main tank 90Y contains yellow ink. The supply passage 91Y connects the main tank 90Y and the inkjet head 30Y. The supply valve 92Y is provided in the supply passage 91Y. The supply valve 92Y is an electromagnetic valve. When the supply valve 92Y is in an open state, the yellow ink flows out of the main tank 90Y, flows through the supply passage 91Y, and is supplied to the inkjet head 30Y. When the supply valve 92Y is in a closed state, the yellow ink does not flow through the supply passage 91Y. In this case, the yellow ink is not supplied from the main tank 90Y to the inkjet head 30Y.

The main tank 90M contains magenta ink. The supply passage 91M connects the main tank 90M and the inkjet head 30M. The supply valve 92M is provided in the supply passage 91M. The supply valve 92M is an electromagnetic valve. When the supply valve 92M is in an open state, the magenta ink flows out of the main tank 90M, flows through the supply passage 91M, and is supplied to the inkjet head 30M. When the supply valve 92M is in a closed state, the magenta ink does not flow through the supply passage 91M. In this case, the magenta ink is not supplied from the main tank 90M to the inkjet head 30M.

The main tank 90C contains cyan ink. The supply passage 91C connects the main tank 90C and the inkjet head 30C. The supply valve 92C is provided in the supply passage 91C. The supply valve 92C is an electromagnetic valve. When the supply valve 92C is in an open state, the cyan ink flows out of the main tank 90C, flows through the supply passage 91C, and is supplied to the inkjet head 30C. When the supply valve 92C is in a closed state, the cyan ink does not flow through the supply passage 91C. In this case, the cyan ink is not supplied from the main tank 90C to the inkjet head 30C.

The main tank 90K contains black ink. The supply passage 91K connects the main tank 90K and the inkjet head 30K. The supply valve 92K is provided in the supply passage 91K. The supply valve 92K is an electromagnetic valve. When the supply valve 92K is in an open state, the black ink flows out of the main tank 90K, flows through the supply passage 91K, and is supplied to the inkjet head 30K. When the supply valve 92K is in a closed state, the black ink does not flow through the supply passage 91K. In this case, the black ink is not supplied from the main tank 90K to the inkjet head 30K.

The inkjet heads 30Y, 30M, 30C, and 30K have the same configuration. The main tanks 90Y, 90M, 90C, and 90K have the same configuration. The supply passages 91Y, 91M, 91C, and 91K have the same configuration. The supply valves 92Y, 92M, 92C, and 92K have the same configuration.

In the embodiment, when the inkjet heads 30Y, 30M, 30C, and 30K are not differentiated from one another or are collectively referred to as "inkjet heads 30." When the main tanks 90Y, 90M, 90C, and 90K are not differentiated from one another or are collectively referred to as "main tanks 90." When the supply passages 91Y, 91M, 91C, and 91K are not differentiated from one another or are collectively referred to as "supply passages 91." When the supply valves 92Y, 92M, 92C, and 92K are not differentiated from one another or are collectively referred to as "supply valves 92." A combination of two or more of the inkjet heads 30, main tanks 90, supply passages 91, and supply valves 92 is a combination for the same color.

When a pattern is recorded on the recording medium 15 by the inkjet recording device 10, the conveyor 20 continuously conveys the recording medium 15 in the conveying direction. The inkjet heads 30Y, 30M, 30C, and 30K eject ink of the corresponding color toward the recording medium 15 at a predetermined timing. The ink of each color ejected from the inkjet heads 30Y, 30M, 30C, and 30K lands on the surface of the recording medium 15. A pattern is recorded on the surface of the recording medium 15 by the ink of each color that has landed.

<Inkjet head>
The inkjet head 30 will be described with reference to Figures 2 and 3. In this description, the directions used to identify the inkjet head 30 correspond to directions based on a state in which the inkjet head 30 is provided in the inkjet recording apparatus 10.

The inkjet head 30 comprises an ink chamber 40, a top plate 50, multiple rods 60, multiple piezoelectric elements 70, and multiple displacement magnification mechanisms 80. In the inkjet head 30, the ink chamber 40 and the top plate 50 are integrated. One ink chamber 40 is provided for each of the multiple rods 60. One top plate 50 is provided for each of the multiple displacement magnification mechanisms 80. One of the multiple rods 60 is provided for each nozzle 41.

In the inkjet head 30, the number of nozzles 41 is five. Therefore, the inkjet head 30 has five rods 60. The five rods 60 are rods of the same specifications. In the embodiment, when the five rods 60 are to be distinguished from one another, they are referred to as "rod 60a," "rod 60b," "rod 60c," "rod 60d," and "rod 60e." When no distinction is made or when they are referred to collectively, they are referred to as "rod 60."

Similarly, the inkjet head 30 in Figures 2 and 3 has five piezoelectric elements 70. The five piezoelectric elements 70 are piezoelectric elements with the same specifications. In the embodiment, when the five piezoelectric elements 70 are to be distinguished from one another, they are referred to as "piezoelectric element 70a," "piezoelectric element 70b," "piezoelectric element 70c," "piezoelectric element 70d," and "piezoelectric element 70e." When no distinction is made or when they are referred to collectively, they are referred to as "piezoelectric element 70."

Similarly, the inkjet head 30 in Figures 2 and 3 has five displacement magnification mechanisms 80. The five displacement magnification mechanisms 80 are displacement magnification mechanisms with the same specifications. In the embodiment, when the five displacement magnification mechanisms 80 are to be distinguished from one another, they are referred to as "displacement magnification mechanism 80a," "displacement magnification mechanism 80b," "displacement magnification mechanism 80c," "displacement magnification mechanism 80d," and "displacement magnification mechanism 80e." When no distinction is made or when they are referred to collectively, they are referred to as "displacement magnification mechanism 80."

The ink chamber 40 stores ink that has flowed from the main tank 90 through the supply passage 91. The ink in the ink chamber 40 is stored under pressure.

The top plate 50 is provided above the displacement magnification mechanisms 80a, 80b, 80c, 80d, and 80e in the height direction in a state corresponding to the displacement magnification mechanisms 80a, 80b, 80c, 80d, and 80e. The top plate 50 contacts the top surfaces of the displacement magnification mechanisms 80a, 80b, 80c, 80d, and 80e, each of which has the same height on the upper surface in the height direction.

The rod 60 moves back and forth within the ink chamber 40. When ink is not being ejected from the nozzle 41, the rod 60 is pressed against the nozzle 41 by the leaf spring 82 of the displacement magnification mechanism 80, and the rod 60 is in a lowered state. When a voltage is applied to the piezoelectric element 70, the leaf spring 82 deforms, pulling the rod 60 upward and ejecting ink from the nozzle 41.

A d33 mode stacked type piezoelectric element is used as the piezoelectric element 70. Furthermore, a large piezoelectric element capable of deformation of 100 nm or more is used as the piezoelectric element 70. As a reference example, in a known inkjet head, the amount of displacement of the piezoelectric element is about several tens of nm.

The displacement magnification mechanism 80 includes a base portion 81 and a leaf spring 82. A piezoelectric element 70 is attached to the base portion 81. The leaf spring 82 magnifies the displacement of the piezoelectric element 70 attached to the base portion 81 and transmits it to the rod 60. Note that, although one piezoelectric element 70 is attached to one displacement magnification mechanism 80 in Figures 2 and 3, two or more piezoelectric elements 70 may be attached to one displacement magnification mechanism 80, and the number of piezoelectric elements 70 that can be attached is not limited.

Looking at the relative positions of the nozzle 41a, rod 60a, piezoelectric element 70a, and leaf spring 82a, they are designed so that their centers are positioned on the same axis. This allows the amount of displacement to be transmitted efficiently, and also allows for a compact design that does not take up much space.

Similarly, the positional relationship between the nozzle 41b, rod 60b, piezoelectric element 70b, and leaf spring 82b is designed so that their centers are aligned on the same axis. In this way, the centers of the rod 60, piezoelectric element 70, and leaf spring 82 for each nozzle are aligned on the same axis, making it possible to make the inkjet head 30 compact.

<Modification>
The embodiment can also be as follows. Some of the configurations of the modified examples shown below can be appropriately combined and adopted. Below, we will explain the points that are different from the above, and will appropriately omit explanations of similar points.

(1) In the inkjet recording device 10 of FIG. 1, an inkjet recording device equipped with a so-called line-type inkjet head has been described as an example, but the present invention is not limited to this, and may be an inkjet recording device equipped with a serial-type inkjet head that records an image while moving a carriage back and forth in the main scanning direction. Serial-type inkjet heads and inkjet recording devices equipped with them are well-known configurations that have already been put into practical use. Therefore, further explanation regarding these will be omitted.

(2) The piezoelectric element 70 used in the inkjet head 30 is larger than normal ones and generates a large amount of heat, so it is advisable to provide a cooling mechanism for cooling the piezoelectric element 70. The cooling mechanism may be configured, for example, by providing through holes in the base portion 81 of each displacement magnification mechanism 80 and blowing cooled air from the through holes onto the piezoelectric element 70. Other examples include attaching fins for dissipating heat to the displacement magnification mechanism 80, or using materials with good thermal conductivity for the components of the displacement magnification mechanism 80.

REFERENCE SIGNS LIST 10 Inkjet recording device, 15 Recording medium, 20 Conveyor 30, 30Y, 30M, 30C, 30K Inkjet head 31 Carriage, 40 Ink chamber, 41 Nozzle, 50 Top plate 60, 60a, 60b, 60c, 60d, 60e Rod 70, 70a, 70b, 70c, 70d, 70e Piezoelectric element 80, 80a, 80b, 80c, 80d, 80e Displacement magnification mechanism 81 Base portion, 82 Leaf spring 90, 90Y, 90M, 90C, 90K Main tank 91, 91Y, 91M, 91C, 91K Supply passage 92, 92Y, 92M, 92C, 92K Supply valve

Claims (5)

an ink chamber including a first nozzle and a second nozzle on a first side surface for ejecting ink and for storing ink;
A first rod that moves back and forth within the ink chamber;
A second rod that moves back and forth within the ink chamber;
a first piezoelectric element that moves the first rod back and forth to eject ink from the first nozzle;
a second piezoelectric element that moves the second rod back and forth to eject ink from the second nozzle;
a first displacement magnifying mechanism that magnifies the displacement of the first piezoelectric element;
a second displacement amplifying mechanism that amplifies the displacement of the second piezoelectric element;
a top plate to which the first displacement magnifying mechanism and the second displacement magnifying mechanism are fixed on a second side opposite to the first side;
a cooling mechanism for cooling the first piezoelectric element and the second piezoelectric element,
The cooling mechanism includes:
An inkjet head that blows cooled air onto the first piezoelectric element and the second piezoelectric element through through holes provided in the base portions of the first displacement magnifying mechanism and the second displacement magnifying mechanism. The inkjet head according to claim 1, wherein the first displacement magnification mechanism has a first base portion to which the first piezoelectric element is attached and a first leaf spring, and the second displacement magnification mechanism has a second base portion to which the second piezoelectric element is attached and a second leaf spring. An inkjet head according to claim 1 or claim 2, in which the ink in the ink chamber is pressurized. The inkjet head according to claim 2 , wherein the first nozzle, the first rod, the first piezoelectric element, and the first leaf spring are arranged on a same axis. An inkjet recording device equipped with an inkjet head according to any one of claims 1 to 4.