JP2023082362A - Ink jet head and ink jet recording device - Google Patents

Abstract

To provide an ink jet head and an ink jet recording device which can arrange nozzles in the higher density while suppressing reduction in discharge accuracy of ink.SOLUTION: An ink jet head includes a head chip in which a pressure chamber substrate that has a pressure chamber (71) for applying pressure fluctuation to ink inside the ink jet head, a nozzle substrate that has a nozzle (N) for discharging the ink and a channel substrate that has a communication flow channel for making the nozzle (N) communicate to the pressure chamber (71) overlap each other. Regarding the cross-sectional shape vertical to the direction of overlapping of the pressure chamber (71), the first width in the first direction (X) is half or less of the first length in the second direction vertical to the first direction, and the second width in the first direction (X) in at least a portion (722) from the side contacting the nozzle (N) of the communication flow channel (72) is wider than the first width and the first diameter of a connection port being one end contacting the channel substrate of the nozzle (N).SELECTED DRAWING: Figure 6

Description

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

2. Description of the Related Art There is an inkjet recording apparatus that includes an inkjet head that ejects ink from a plurality of nozzles and that records an image or the like with the ejected ink. As one of the shapes of the inkjet head, there is one in which a plurality of substrates through which ink flow paths penetrate are stacked and ink is ejected from nozzle openings of a nozzle substrate located in the bottom layer. From the viewpoint of increasing the nozzle array density and stabilizing the ink ejection characteristics, the nozzle diameter should be smaller than the size of the ink flow path. is narrower than the width in the direction perpendicular to the arrangement direction (Patent Document 1).

WO2018/225553

However, the nozzle substrate and other parts of the head chip are bonded together with an adhesive. If an attempt is made to bring them into close contact with each other to fix them, it is inevitable that the adhesive protrudes into the ink flow path and solidifies. If the protruding adhesive enters the nozzle, there is a problem that the ink ejection characteristics are significantly deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inkjet head and an inkjet recording apparatus capable of arranging nozzles at a higher density while suppressing deterioration in ink ejection accuracy.

In order to achieve the above object, the invention according to claim 1,
a pressure chamber substrate having pressure chambers that apply pressure fluctuations to the ink inside;
a nozzle substrate having nozzles for ejecting ink;
a channel substrate having a communication channel for communicating the nozzle and the pressure chamber;
with a head chip that overlaps the
A cross-sectional shape of the pressure chamber perpendicular to the overlapping direction has a first width in a first direction that is less than or equal to half a first length in a second direction perpendicular to the first direction. ,
A second width in the first direction of at least a portion of the communication channel from the side in contact with the nozzle is a first diameter of a connection port that is one end of the nozzle in contact with the channel substrate. The inkjet head is characterized in that the width is wider than the first width.

Further, the invention according to claim 2 is the inkjet head according to claim 1,
The nozzle has a tapered shape in which a diameter gradually decreases from the first diameter from the connection port to an opening for ejecting ink.

Further, the invention according to claim 3 is the inkjet head according to claim 1 or 2,
The first width is smaller than the first diameter.

Further, the invention according to claim 4 is the inkjet head according to any one of claims 1 to 3,
The second width is wider than the width obtained by adding twice the tolerance, which is the maximum value of a predetermined manufacturing error associated with the bonding of the channel substrate and the nozzle substrate, to the first diameter. and

Further, the invention according to claim 5 is the inkjet head according to claim 4,
The tolerance is 50 μm or less.

Further, the invention according to claim 6 is the inkjet head according to any one of claims 3 to 5,
The first diameter is 50 μm or more and 100 μm or less.

Further, the invention according to claim 7 is the inkjet head according to any one of claims 3 to 6,
The tapered shape of the nozzle has a taper angle of 10 degrees or more.

Further, the invention according to claim 8 is the inkjet head according to any one of claims 1 to 7,
The nozzle substrate is characterized by being a metal member.

Further, the invention according to claim 9 is the inkjet head according to any one of claims 1 to 8,
A thickness of the flow path substrate relating to the communication flow path is 100 μm or less.

Further, the invention according to claim 10 is the inkjet head according to any one of claims 1 to 9,
The pressure chamber substrate is characterized in that piezoelectric members forming drive walls and a plurality of pressure chambers penetrating through the drive walls are alternately arranged in the first direction.

Further, the invention according to claim 11 is the inkjet head according to any one of claims 1 to 10,
The channel substrate has individual ink discharge channels branching from the plurality of communication channels,
The inkjet head is characterized by comprising a common ink discharge path that communicates with the plurality of individual ink discharge paths.

According to a twelfth aspect of the invention, there is provided an inkjet recording apparatus comprising the inkjet head according to any one of the first to eleventh aspects.

According to the present invention, there is an effect that the nozzles can be arranged at a higher density while suppressing deterioration of ink ejection accuracy.

1 is a schematic diagram showing an overall configuration of an image forming apparatus; FIG. FIG. 3 is a bottom view of the head unit as seen from the ink ejection surface side; It is a figure explaining the schematic structure of an inkjet head. FIG. 4 is a diagram for explaining ink flow paths in a head chip; 4 is a cross-sectional view of a head chip; FIG. It is a figure explaining the cross section of a head chip.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus 1, which is an inkjet recording apparatus of this embodiment. FIG. 1 shows the case where the image forming apparatus 1 is viewed from the front.

The image forming apparatus 1 is an inkjet recording apparatus that ejects ink from nozzles. For example, the image forming apparatus 1 has a line head. It is a printer that can record color images by
The image forming apparatus 1 includes a medium supply section 10, a forming operation section 20, a medium ejection section 30, and the like. In the image forming apparatus 1, the recording medium M stored in the medium feeding section 10 is conveyed along a predetermined conveying path to the forming operation section 20 and discharged to the medium discharging section 30 after an image is recorded. .

The medium supply unit 10 sends the recording medium M stored inside to the forming operation unit 20 one by one.
Examples of the recording medium M include printing paper of various thicknesses, cells, films, fabrics, and various other media, and here, media that can be curvedly carried on the outer peripheral surface of the image forming drum 21 can be used.

The medium supply unit 10 has a supply tray 11 that stores the recording medium M and a feeder board 12 that conveys the recording medium M from the supply tray 11 to the forming operation unit 20 . The supply tray 11 is a plate-like member on which one or more recording media M can be placed. The supply tray 11 is provided so as to move up and down according to the amount of the recording medium M placed on the supply tray 11. In the vertical movement direction, the uppermost recording medium M is conveyed by the feeder board 12. is held in
The feeder board 12 has a conveying mechanism that drives a ring-shaped belt 123 carried by a plurality of (for example, two) rollers 121 and 122 on the inside to convey the recording medium M on the belt 123, It has a supply unit for transferring the topmost recording medium M placed on the belt 123 . The feeder board 12 conveys the recording medium M delivered on the belt 123 by the supply unit along the belt 123 .

The forming operation section 20 includes an image forming drum 21, a delivery unit 22, a drum heater 231, a head unit 24 (ejection operation section), an irradiation section 25, a delivery section 26, and the like.

The image forming drum 21 has a cylindrical outer shape, carries a maximum of three sheets of recording medium M on the outer peripheral surface of the cylindrical portion, and conveys the recording medium M according to the rotational movement about the central axis of the cylinder. Carrying operation is performed.

The delivery unit 22 delivers the recording medium M delivered from the medium supply section 10 to the image forming drum 21 . The transfer unit 22 includes a swing arm portion 221 that carries one end of the recording medium M conveyed by the feeder board 12, and a cylindrical transfer drum that transfers the recording medium M carried by the swing arm portion 221 to the image forming drum 21. 222 and the like, the recording medium M on the feeder board 12 is picked up by the swing arm 221 and transferred to the transfer drum 222, thereby guiding the recording medium M in the direction along the outer peripheral surface of the image forming drum 21 to form an image. Hand over to drum 21 .

The drum heater 231 is positioned near the outer peripheral surface of the image forming drum 21 and heats the outer peripheral surface and the recording medium M. Here, the drum heater 231 is positioned between the transfer position of the recording medium M to the image forming drum 21 by the transfer unit 22 and the image forming position on the recording medium M by the head unit 24 in the rotation direction of the image forming drum 21 . is provided. The outer peripheral surface of the image forming drum 21 is heated by the drum heater 231 to bring the recording medium M to an appropriate temperature. As a result, when the ink lands on the recording medium M, the curing speed of the recording medium M can be appropriately maintained, and a high-quality image can be stably recorded. An infrared heater, for example, is used for the drum heater 231 .

The head unit 24 has a surface (nozzle opening) facing one image formation target surface of the recording medium M that moves according to the rotation of the image forming drum 21 in the head unit 24 . An image is recorded by ejecting ink droplets at appropriate timing from a plurality of nozzle openings provided on the recording medium M and landing them on the image formation target surface of the recording medium M. In the image forming apparatus 1 of the present embodiment, a plurality of head units 24 are arranged at predetermined intervals in the conveying direction of the recording medium M, here, four head units corresponding to each of the four colors of ink. The four head units 24 output C (cyan), M (magenta), Y (yellow), and K (black) inks, respectively. These inks may undergo a phase change between a sol state and a gel state depending on temperature, and may be cured by irradiation with ultraviolet rays, for example. The ink may be heated by an ink heater (not shown) as necessary.

The irradiation unit 25 irradiates energy rays (electromagnetic waves) with a predetermined wavelength, here, ultraviolet rays in the near-ultraviolet region (wavelength of about 400 nm), and irradiates ink ejected from the head unit 24 and landing on the recording medium M (that is, , an image recorded with the ink) is cured and fixed. The irradiation unit 25 has, for example, a light-emitting diode (LED 251) that emits ultraviolet rays, and applies a voltage to the LED 251 to cause it to emit light and emit ultraviolet rays. The irradiation unit 25 is located downstream of the landing position of the ink ejected from the head unit 24 onto the recording medium M conveyed by the rotation of the image forming drum 21 and from the position where the recording medium M is handed over to the delivery unit 26 . Also, the upstream side is the ink fixing position, that is, the recording medium M is positioned so that it can be irradiated with ultraviolet rays.

In addition, the structure which emits an ultraviolet-ray in the irradiation part 25 is not restricted to LED. The irradiation unit 25 may have, for example, a mercury lamp. Further, when the ink has a property of being cured by receiving energy rays other than ultraviolet rays, various light sources emitting energy rays of wavelengths for curing the ink are provided instead of the above-described configuration for emitting ultraviolet rays.

The delivery unit 26 conveys the recording medium M after the image forming operation is completed and the ink that has landed is cured to the medium discharge unit 30 . The delivery section 26 has a cylindrical delivery roller 261, a plurality (for example, two) of rollers 262 and 263, and a ring-shaped belt 264 supported by the rollers 262 and 263 on the inner surface. The transfer roller 261 receives the recording medium M from the image forming drum 21 and guides it onto the belt 264 . The delivery unit 26 conveys the recording medium M delivered from the delivery roller 261 onto the belt 264 to the medium ejection unit 30 by moving the recording medium M together with the belt 264 that circulates as the rollers 262 and 263 rotate.

The medium discharge section 30 stores the recording medium M delivered from the forming operation section 20 by the delivery section 26 until it is taken out by the user. The medium ejection unit 30 has a plate-like ejection tray 31 and the like, and the recording medium M on which an image has been formed is placed on the ejection tray 31 .
It should be noted that the transportation of the recording medium M is not limited to the configuration described above. The recording medium M may be transported on a circulating belt or by rollers. Further, the transport surface may be a flat surface, and the head units 24 and the irradiation units 25 may be arranged in a line from the upstream side to the downstream side in the transport direction so as to face the flat surface. Also, the mechanism for transferring the recording medium M from the medium supply unit 10 to the forming operation unit 20 and the configuration for discharging the recording medium M from the forming operation unit 20 to the medium discharge unit 30 may be different from those described above.

FIG. 2 is a bottom view of the head unit 24 looking at the ink ejection surface side.
Each head unit 24 has a plurality of inkjet heads 240, eight in this case, and these inkjet heads 240 are fixedly held by a support member. A head chip 241 positioned on the bottom surface of each inkjet head 240 has openings of a plurality of nozzles N for ejecting ink. The arrangement range of the nozzles N in each inkjet head 240 partially overlaps with the other inkjet heads 240 in the X direction (first direction) perpendicular to the transport direction (Y direction), and covers the entire printable width of the recording medium M. extends across. The nozzles N of each inkjet head 240 (head chip 241) are positioned on nozzle rows extending in the X direction at four positions in the Y direction (second direction). The nozzle positions on each nozzle row are shifted from each other by 1/4 of the interval between the nozzles N in each nozzle row. Lined up.

FIG. 3 is a diagram for explaining the schematic structure of the inkjet head 240. As shown in FIG.
The inkjet head 240 has a cover H attached to the upper side of a housing F positioned at the bottom. The bottom surface of the housing F is open to expose the head chip 241 described above. An inlet 2421 into which supplied ink flows and outlets 2422 and 2423 into which discharged ink flows are extended on the upper surface side of the housing F. As shown in FIG. The inlet 2421 and the outlets 2422 and 2423 are connected to manifolds located above the head chip 241 in the housing F, respectively, and ink is supplied to the ink reservoir therein, and ink is discharged from the ink reservoir. be done. Ink is sent from the manifold to individual nozzles N of the head chip 241 .

A circuit board 243 connects the inside and outside of the cover H through the upper end of the cover H, and a voltage signal is applied to electrodes for causing the head chip 241 to eject ink from the nozzles N through the drive board in the housing F. is sent. The circuit board 243 is not particularly limited, but may be a flexible circuit board.

FIG. 4 is a diagram for explaining the ink flow paths in the head chip 241. As shown in FIG.
FIG. 4(a) shows a part of the nozzle N side of the cross section in the YZ plane of one of the nozzles N shown in FIG.

The head chip 241 has a nozzle plate 63 (nozzle substrate) having nozzles N in the bottom layer, and above it (on the +Z side) a channel plate 62 (channel substrate, also called a spacer channel substrate) and pressure chambers. A substrate 61 is laminated in order. As described above, ink is supplied from the ink reservoir of the manifold located further above the pressure chamber substrate 61 .

The pressure chamber substrate 61 is made of a piezoelectric member, and the pressure chambers 71 penetrate vertically (in the Z direction). An electrode (not shown) is positioned along the wall surface of the pressure chamber 71, and when a voltage is applied to the electrode from the circuit board 243 through the drive substrate, the piezoelectric member forming the drive wall is deformed to form the pressure chamber. A pressure fluctuation is applied to the ink inside 71 . The piezoelectric member here deforms in a shear mode, although not limited thereto. Also, the portion of the pressure chamber substrate 61 in contact with the flow path plate 62 has a recess separated from the pressure chamber 71, and the recess serves as a common discharge flow path 74 (common ink discharge path), which will be described later. .

The channel plate 62 has communication channels 72 that communicate the pressure chambers 71 of the pressure chamber substrate 61 and the nozzles N of the nozzle plate 63 . The communication channel 72 vertically penetrates the channel plate 62 . The communication channel 72 includes an upper channel 721 having the same length as the pressure chamber 71 in a cross section parallel to the XY plane (perpendicular to the Z direction, which is the direction in which the substrates overlap in the head chip 241), and an upper channel 721 having the same length as the pressure chamber 71. and a long lower channel 722 . Separate discharge channels 73 (individual ink discharge channels) branch off from both ends of the communication channel 72 in the Y direction and are connected to the common discharge channel 74 . Unlike the pressure chambers 71 and the nozzles N, the channel plate 62 is not directly related to ink ejection, and works in the direction of lowering the resonance frequency related to the vibration of the ink by the length of the communication channel 72. For example, it is preferably 700 μm or less, and particularly preferably 100 μm or less. On the other hand, the lower limit of the length of the communication flow path 72 (thickness of the flow path plate 62) is that the lower flow path 722 should be able to reduce ink stagnation in the nozzle N at the minimum. It may be minute in range, for example 1 μm or more.

The nozzle plate 63 has nozzles N. As shown in FIG. One end of the nozzle N communicates with the communication channel 72, and the other is exposed and opened to the outside. The nozzle plate 63 is a metal member such as SUS or nickel. An exposed portion (outer surface) such as the bottom surface (−Z side) of the nozzle plate 63 is coated with a repellent (not shown) to prevent troubles such as poor ink ejection and poor maintenance due to adhesion of unnecessary ink and drying and curing. It may be covered with a water film or the like (the film itself is not included in the nozzle plate 63).

FIG. 4(b) shows one of two rows of nozzles adjacent in the Y direction among the nozzle rows extending in the X direction shown in FIG. showing the part. The pressure chamber 71 corresponding to each nozzle N has a width W1 (first width) in the X direction (direction along the nozzle row) and a length L1 (first width) in the Y direction (direction perpendicular to the nozzle row). 1 length). In the cross-sectional shape of the pressure chamber 71, the length L1 is significantly longer than the width W1 (that is, the aspect ratio is high), where L1≧2×W1 (where the width W1 is half or less than the length L1). According to the positional relationship of the nozzles N, the pressure chambers 71 corresponding to each nozzle row are alternately arranged with the piezoelectric members (that is, drive walls) at intervals of 4D (four times the nozzle interval D) in the X direction. These two rows of pressure chambers 71 are arranged alternately in a houndstooth pattern, so the distance between these two rows of pressure chambers 71 in the X direction is half (2D) of the distance 4D. The thickness T of the piezoelectric member (drive wall) between two pressure chambers 71 adjacent in the X direction according to the same nozzle row is the distance 4D minus the width W1 of the pressure chamber (T=4D-W1). is.

FIG. 5 is a cross-sectional view taken along the cross-sectional line BB in FIGS. 4(a) and 4(b).
As described above, the communication channel 72 is divided into the upper channel 721 and the lower channel 722 (at least partly from the side in contact with the nozzle N) (FIG. 5A). is equal to the width W1 of the pressure chamber 71, the width W2 (second width) of the lower flow path 722 in the X direction is wider than the width W1.

The cross-sectional shape of the nozzle N in the X direction is the same truncated cone shape as the cross-sectional shape in the Y direction shown in FIG. ) in which the diameter (diameter φ) gradually decreases. When the taper angle, that is, the inclination angle of the inner wall surface of the nozzle N with respect to the Z-axis direction, is set to, for example, 10 degrees or more, high-speed ejection of ink becomes possible stably. Further, when the nozzle plate 63 is a metal member, in the punching process for forming the nozzles N, it is easier to form the nozzles N with a slight taper angle. The maximum diameter φ0 (the first diameter, that is, the diameter φ at the connection port Ni) is larger than the width W1 and smaller than the width W2 (W1<φ0<W2). Furthermore, as shown in FIG. 5(b), the relative position of the nozzle plate 63 bonded with the adhesive to the pressure chamber substrate 61 and the channel plate 62 which are integrally formed may have a minute deviation (manufacturing error). error) can occur. Even considering the maximum value (tolerance d) of the width (error) allowed as a minute deviation between the central axis of the pressure chamber 71 and the communication channel 72 and the central axis of the nozzle N, the connection port of the nozzle N The relationship W2≧φ0+2d (that is, the width W2 is wider than the maximum diameter φ0 plus twice the tolerance d) is satisfied so that Ni falls within the range of the cross section of the communication channel 72 . This tolerance depends on the diameter φ of the nozzle N, particularly the amount of ink ejected per droplet, etc., and is not particularly limited. The tolerance is 50 μm or less.

FIG. 6 is a cross-sectional view of the head chip 241 along the cross-sectional line CC in FIG. 4(a).
As described above, the lower flow path 722 is positioned so as to enclose the pressure chamber 71 that is longer in the Y direction than the width in the X direction in plan view. The ratio between the width W1 and the length L1 of the pressure chamber 71 may be different from the ratio between the width W2 and the length L2 of the lower flow path 722 . Further, the connection port Ni of the nozzle N protrudes in the width direction (X direction) from the range of the pressure chamber 71 in plan view, and is contained inside the lower flow path 722 in plan view.

In the shear mode inkjet head 240, if the thickness of the piezoelectric member between the pressure chambers 71 arranged in the X direction is reduced, it affects deformation and applied voltage during deformation, so it is difficult to reduce the thickness T. Therefore, the width W1 of the pressure chamber 71 is narrowed in order to narrow the interval between the nozzles in the nozzle row.

On the other hand, the shape and size of the nozzles N directly affect ink ejection, and cannot be freely changed. In addition, if the ink does not flow smoothly into the nozzle N and there is a portion where the ink stagnates, the ink ejection characteristics from the nozzle N also deteriorate. Therefore, it is not preferable that the connection port Ni of the nozzle N has a portion wider than the connection surface of the communication channel 72 with the nozzle N. In the inkjet head 240, as described above, the width W1 is set to be smaller than the maximum diameter φ0 of the nozzle N near the pressure chamber 71, and the connection portion of the communication channel 72 with the nozzle N is partially set to the width W1 and the maximum diameter. By setting the width W2 wider than φ0 (diameter), the interval 4D between the nozzle rows is reduced while suppressing the deterioration of the ink ejection characteristics from the nozzles N.

The tapered shape of the nozzle N is more stable and facilitates high-speed ejection of ink. increases with the taper angle. By setting the width W2 of the lower flow path 722 larger than the maximum diameter φ0 in this manner, it is possible to perform appropriate ink ejection without deteriorating the ink ejection characteristics.

As described above, the inkjet head 240 of this embodiment includes the pressure chamber substrate 61 having the pressure chambers 71 for applying pressure fluctuations to the ink inside, the nozzle plate 63 having the nozzles N for ejecting the ink, and the nozzles N A head chip 241 is provided on which a channel plate 62 having a communication channel 72 communicating with the pressure chamber 71 is overlapped. The cross-sectional shape of the pressure chamber 71 perpendicular to the stacking direction of the substrates has a width W1 in the X direction that is half or less than a length L1 in the Y direction perpendicular to the X direction. The width W2 in the X direction of the lower channel 722, which is at least part of the contact side, is larger than the diameter (maximum diameter φ0) and the width W1 of the connection port Ni, which is one end of the nozzle N contacting the channel plate 62. wide.
In this way, since the side of the communication channel 72 that contacts the nozzles N has a portion wider than the maximum diameter φ0 and the width W1, when the nozzle plate 63 is bonded to the channel plate 62, the bonding surface is Since a small amount of leaking adhesive is suppressed from entering the nozzle N, deterioration of the ejection characteristics of the nozzle N is suppressed, and ink can be ejected more stably.
In addition, if the width of the ink flow path expands discontinuously, the ink tends to stagnate at the widened corners. By widening the width of the ink flow path on the upstream side, it is possible to suppress such deterioration in ejection characteristics. In particular, by widening the width of the flow path only in the flow path plate 62 that does not deform, it is possible to suppress adverse effects on ink ejection even if the width W1 of the pressure chamber 71 is narrowed in order to arrange the nozzles N at a high density. .

Also, the width W1 may be smaller than the maximum diameter φ0. In this way, even if the width of the pressure chamber 71 is smaller than the maximum diameter φ0 of the nozzles N, the deterioration of the ink ejection characteristics from the nozzles N can be suppressed, so that the nozzles N can be arranged at a higher density.

Further, the nozzle N has a tapered shape in which the diameter φ gradually decreases from the maximum diameter φ0 from the connection port Ni to the opening Ne for ejecting ink. As a result, the ink can be ejected more stably and at high speed. Further, since the nozzles N can be easily formed in the nozzle plate 63 made of a metal member, the durability of the head chip 241 can be improved as compared with the conventional nozzle plate made of resin or the like.

Further, the width W2 is wider than the maximum diameter φ0 plus twice the tolerance d related to bonding between the channel plate 62 and the nozzle plate 63 . That is, even if the bonding position is displaced to the maximum allowable extent, since the connection port Ni of the nozzle N is included in the lower flow path 722 in plan view, the ink ejection characteristics from the nozzle N are not adversely affected as described above. can be suppressed.

Also, the above tolerance is 50 μm or less. As a result, the axis of the ink flow from the pressure chamber 71 to the nozzle N does not deviate greatly at the nozzle spacing of many of the current inkjet heads 240, so that the ink ejection characteristics are not degraded.

Further, the maximum diameter φ0 of the nozzle N is 50 μm or more and 100 μm or less. Even if the connection port Ni is set larger than the diameter of the opening Ne as described above, the nozzles N can be arranged at a high density compared to the size of the head chip 241 .

Further, the taper angle of the tapered shape of the nozzle N is 10 degrees or more. This makes it possible to stably eject ink at high speed. Moreover, even if the nozzle plate 63 is made of a metal member, the nozzles N can be easily formed by punching or the like, and an increase in cost can be suppressed.

Also, the nozzle plate 63 is a metal member. Thereby, the durability of the head chip 241 can be improved. Also in this case, the above structure enables the nozzles N to be arranged at a higher density.

Further, the thickness of the channel plate 62 related to the communication channel 72 is preferably 700 μm or less, more preferably 100 μm or less. As described above, the channel plate 62 itself has nothing to do with the application of pressure fluctuations to the ink, nor does it have anything to do with the ink ejection operation. function in that direction. Therefore, it is necessary to connect the pressure chamber 71 and the nozzle N, and the lower flow path 722 should not be longer than the length required to suppress the deterioration of the discharge characteristics of the nozzle N as described above. , the deterioration of the performance of the inkjet head 240 can be suppressed.

In the pressure chamber substrate 61, piezoelectric members forming drive walls and a plurality of pressure chambers 71 passing through the drive walls are alternately arranged in the X direction. Such a structure in which both side surfaces of the pressure chamber 71 are sandwiched between piezoelectric members for driving is generally applied to ink by deformation of the piezoelectric member in a shear mode. In this configuration, it is difficult to reduce the thickness of the driving wall, so the width W1 of the pressure chamber 71 and the like is reduced with respect to the length L1 and the maximum diameter φ0 by partially leaving the lower flow path 722 as described above. , the nozzles N can be arranged at a high density.

Further, the channel plate 62 has individual discharge channels 73 branching from a plurality of communication channels 72 , and the inkjet head 240 has a common discharge channel 74 communicating with the plurality of individual discharge channels 73 . Since the width W2 of the communication channel 72, particularly the lower channel 722, is locally wide, air bubbles tend to accumulate in this portion. Air bubbles can be effectively discharged, and thus ink can be ejected more stably.

Further, the image forming apparatus 1, which is the inkjet recording apparatus of the present embodiment, includes the inkjet head 240 described above. With such an image forming apparatus 1, it is possible to print a high-resolution and high-precision image by arranging nozzles at a higher density while suppressing deterioration in ejection characteristics.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible.
For example, in the above embodiment, the widths W1 and W2 change stepwise between the upper channel 721 and the lower channel 722 in the channel plate 62, but the wall surface is slightly inclined at the boundary. may Also, the lengths of the upper flow path 721 and the lower flow path 722 (thickness of the flow path plate 62 at the relevant portions) may be changed and set as appropriate.

Also, in the above embodiment, the width W1 of the pressure chamber is smaller than the maximum diameter φ0 of the nozzle N, but this condition is not necessarily satisfied. The width W1 may be greater than or equal to the maximum diameter φ0.

Further, in the above embodiment, the nozzle N has been described as having a tapered shape, but the diameter φ may be constant. Moreover, even when it is tapered, the taper angle may be less than 10 degrees.

Further, in the above embodiment, the nozzle plate 63 is described as being made of a metal member such as SUS or nickel, but it may be made of other metal members. may

Further, the specific numerical values shown in the above embodiment may be appropriately changed according to the resolution of the inkjet head 240, the ejection cycle, and the like.

Also, the arrangement of the nozzles N in the inkjet head 240 is not limited to that shown in the above embodiment. For example, the nozzles N may all be arranged in one line, or may be arranged in a more two-dimensional arrangement. Further, the nozzles N do not have to be strictly aligned in the X direction. Moreover, the pressure chamber 71 does not have to deform according to the deformation of the surrounding piezoelectric member in the shear mode. It may be deformed according to deformation in other modes, such as deformation in a bending mode.

Also, the inkjet head 240 does not necessarily have to include the individual discharge flow path 73 and the common discharge flow path 74 . Also, the individual discharge channels 73 do not have to branch off from both sides of the lower channel 722 in the Y direction.

Further, the inkjet head 240 may be transferred and sold independently of the image forming apparatus 1 .

Further, in the above embodiment, the pressure chamber 71 and the upper flow path 721 are rectangular in plan view, but they do not necessarily have to be rectangular. The corners may be slightly rounded, similar to that shown for lower channel 722 . Also, the nozzle N may not be circular in plan view. It may be oval or rectangular. In this case, the diameter φ and the maximum diameter φ0 may be the maximum distance from the center to the edge of the connection port Ni or the opening Ne.
In addition, the specific configurations, contents and procedures of processing operations, etc. shown in the above embodiments can be changed as appropriate without departing from the scope of the present invention. The scope of the present invention includes the scope of the invention described in the claims and the scope of equivalents thereof.

1 Image Forming Apparatus 10 Medium Supply Section 11 Supply Tray 12 Feeder Boards 121, 122 Roller 123 Belt 20 Forming Operation Section 21 Image Forming Drum 22 Transfer Unit 221 Swing Arm Section 222 Transfer Drum 231 Drum Heater 24 Head Unit 240 Inkjet Head 241 Head Chip 2421 Inlets 2422, 2423 Outlet 243 Circuit board 25 Irradiation unit 26 Delivery unit 261 Transfer rollers 262, 263 Roller 264 Belt 30 Medium discharge unit 31 Discharge tray 61 Pressure chamber substrate 62 Channel plate 63 Nozzle plate 71 Pressure chamber 72 Communication channel 721 Upper channel 722 Lower channel 73 Individual discharge channel 74 Common discharge channel F Housing H Cover M Recording medium N Nozzle Ne Opening Ni Connection port

Claims (12)

a pressure chamber substrate having pressure chambers that apply pressure fluctuations to the ink inside;
a nozzle substrate having nozzles for ejecting ink;
a channel substrate having a communication channel for communicating the nozzle and the pressure chamber;
with a head chip that overlaps the
A cross-sectional shape of the pressure chamber perpendicular to the overlapping direction has a first width in a first direction that is less than or equal to half a first length in a second direction perpendicular to the first direction. ,
A second width in the first direction of at least a portion of the communication channel from the side in contact with the nozzle is a first diameter of a connection port that is one end of the nozzle in contact with the channel substrate. An inkjet head, wherein the width is wider than the first width. 2. An ink jet head according to claim 1, wherein said nozzle has a tapered shape with a diameter gradually decreasing from said first diameter from said connection port to an opening for ejecting ink. 3. The inkjet head according to claim 1, wherein said first width is smaller than said first diameter. The second width is wider than the width obtained by adding twice the tolerance, which is the maximum value of a predetermined manufacturing error associated with the bonding of the channel substrate and the nozzle substrate, to the first diameter. The inkjet head according to any one of claims 1 to 3. 5. An ink jet head according to claim 4, wherein said tolerance is 50 [mu]m or less. 6. The inkjet head according to claim 3, wherein the first diameter is 50 μm or more and 100 μm or less. The inkjet head according to any one of claims 3 to 6, wherein the tapered shape of the nozzle has a taper angle of 10 degrees or more. The inkjet head according to any one of claims 1 to 7, wherein the nozzle substrate is a metal member. The ink jet head according to any one of claims 1 to 8, wherein the thickness of the channel substrate related to the communication channel is 700 µm or less. 10. The pressure chamber substrate according to any one of claims 1 to 9, wherein piezoelectric members forming drive walls and a plurality of pressure chambers passing through the drive walls are alternately arranged in the first direction. 1. The inkjet head according to claim 1. The channel substrate has individual ink discharge channels branching from the plurality of communication channels,
The inkjet head according to any one of claims 1 to 10, further comprising a common ink discharge path communicating with the plurality of individual ink discharge paths. An inkjet recording apparatus comprising the inkjet head according to any one of claims 1 to 11.

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