JP2013252721A - Liquid droplet discharge head and liquid droplet discharge apparatus provided with the same head, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid droplet discharge head improved in handling performance by increasing rigidity of common supply flow path forming members and having high operating reliability with stabilized discharge characteristics.SOLUTION: A liquid droplet discharge head includes a plurality of nozzles 1 arranged like a row, a pressure chamber 3 communicated to each nozzle 1 individually, a pressure generating means 17 for giving the change of pressure to the pressure chamber 3, an individual supply flow path 4 communicated to the pressure chamber 3 individually, and a common supply flow path forming member 10 formed with a common supply flow path 8 communicated to the individual supply flow path 4. A filter 7 is provided in the common supply flow path 8. The common supply flow path 8 is divided into an upstream side common supply flow path 8a and a downstream side supply flow path 8b across the filter 7. An upstream side grating part 9a and a downstream side grating part 9b are formed in the upstream side common supply flow path 8a and the downstream side supply flow path 8b, respectively.

Description

  The present invention relates to a droplet discharge head such as an ink jet recording head, and more particularly to a configuration of a common supply channel before liquid such as ink is dispersed and introduced into individual supply channels.

  An ink jet recording head and an ink jet printer will be described below as an example of a droplet discharge head and an image forming apparatus including the same.

  In the ink jet recording head, ink introduced from an ink tank through an ink supply tube is supplied to a plurality of individual supply channels and pressure chambers via a common supply channel. The ink droplets are ejected from the nozzles by selectively applying pressure to the ink supplied to each pressure chamber.

  If impurities or contaminants are mixed in the supplied ink, the individual flow paths are blocked or ink cannot be ejected due to clogging at the nozzles. Ink jet recording heads greatly affect print quality if any one of a plurality of arranged nozzles is clogged. Therefore, in general, a filter is provided before connection to the ink tank introduction part to prevent intrusion of impurities or the like into the ink flow path.

  However, dust generated at the time of manufacturing the ink jet recording head (for example, frame burrs, ridges, corners, etc. generated during manufacture) cannot be removed. As a countermeasure, Patent Document 1 discloses that a filter for removing dust is provided in the flow path. Specifically, in the individual supply flow path immediately before the common liquid chamber is connected to the individual pressure chamber. Is provided with a filter. Also in Patent Document 2, a sheet-like filter is provided in the individual flow path ink introduction portion immediately before the individual supply flow path. Since there is no partition of the portion communicating with the individual supply flow path, the dust eliminability with respect to filter clogging is improved, and the life due to filter clogging is prolonged compared to Patent Document 1.

  In Patent Document 3, in order to improve the handling performance of the filter portion of one filter plate, a recess is formed using a method of isotropically removing constituent materials such as etching, and a filter hole is formed in the recess. It is disclosed that the handleability is improved by providing a thick portion other than the filter portion. Moreover, since the filter hole is provided in the recess, the pressure loss can be reduced by providing the filter in the thin part.

  In forming the filter, the filter isotropically removes a constituent material such as etching from one side of the metal plate into a predetermined region, so that the depth of the filter is smaller than the thickness of the metal plate. A hole is formed, and the concave portion is formed by isotropically removing a constituent material such as etching from the opposite surface of the metal plate to the entire predetermined region to form a plurality of small holes. A filter hole is formed by penetrating. By laminating a plurality of these plates, a filter section is formed in the ink flow path, and this filter section has a recess and a plurality of filter holes formed in the bottom surface of the recess.

  Currently, there is an increasing need for ink jet printers to achieve both high-speed printing and high-quality printing. In general, ink jet printers are roughly classified into a thermal type and a piezoelectric element type. In the thermal method, since deposits called kogation are generated on the heater when the ink is heated, the heating performance is deteriorated, so that the ejection characteristics of the ink jet recording head are lowered and it is difficult to extend the life of the ink jet recording head. In addition, since the heating unit is in direct contact with the ink and is likely to be corroded and deteriorated, there is a problem that the type of ink that can be used is limited.

  On the other hand, since the piezoelectric element type ink jet recording head uses a vibration plate, the piezoelectric vibrator does not come into contact with the ink, and the piezoelectric vibrator is not corroded or deteriorated by the ink, so that it can cope with various inks. There is an advantage.

  In recent years, the demand for ultraviolet curable ink (UV ink) has increased in the field of printing. Many UV inks have a relatively high viscosity at room temperature. In the case of ejecting high-viscosity ink such as UV ink by a piezoelectric element method, a method of heating the ink in advance using a heater is employed in order to reduce the viscosity of the ink.

  If there is a distribution of heat transfer in the inkjet recording head when heating with a heater, the viscosity of the ink supplied to each channel will be non-uniform, and the droplet discharge speed related to the print quality, the basic discharge of the droplet weight The characteristics are greatly affected.

  As a method for making the ink temperature inside the ink jet recording head uniform, a technique for making the ink temperature (ink viscosity) in the common supply flow path uniform by changing the heat generation density of the heater along the nozzle arrangement direction is disclosed in Patent Literature. 4.

  Recent ink jet recording heads are required to have high density and fine droplet ejection. Therefore, the individual liquid chambers (nozzles, pressure chambers, and individual supply flow paths) of one channel that ejects ink need to be downsized.

  When a pair of filter units are provided corresponding to the inside of one individual liquid chamber supply unit as in Patent Document 1, the transmission area of the filter is reduced. Similarly in Patent Document 2, since the downstream side of the filter immediately becomes an individual liquid chamber, the filter area allocated to the individual liquid chamber is similarly reduced. In this case, even if a small amount of dust is generated and accumulated, the filter transmission effective area is reduced. As the individual liquid chamber becomes smaller, the ratio of the non-functioning filter portion to the filter area increases. In this case, the pressure loss of the filter portion becomes large, and as a result, the ink supply performance decreases.

  In addition, in the case of Patent Document 1, since the liquid chamber is individually divided with respect to one liquid chamber, the dust accumulated in the filter portion is generated in the flow path by a forced pressure to generate a flow having a high flow rate. It is difficult to eliminate.

  In Patent Document 2, since the filter is in the form of a sheet, it is possible to remove dust by a forced flow, but strength is necessary to ensure the handling of the sheet-like filter, and the filter must be thickened to some extent. I must.

  In recent years, ink jet recording heads are required to increase the discharge amount per unit time from the viewpoint of high-speed printing for both high resolution and small droplet discharge. Therefore, the flow rate that passes through the flow path per unit time in order to perform high-speed printing also increases. When the supply flow rate to the flow path is large, the pressure loss is expected to increase.

  In general, the pressure loss is defined by (pressure loss) = (fluid resistance of the flow path) × (flow rate). In order to reduce the pressure loss while increasing the ink supply flow rate, the fluid resistance must be reduced. In the case of a filter having the same filtration accuracy and aperture ratio, the fluid resistance can be reduced by reducing the thickness of the filter in the transmission direction as much as possible. As described above, Patent Document 2 must ensure a certain filter thickness for handling, and is therefore not suitable for making an inkjet recording head compatible with high-speed printing.

  In the case of Patent Document 3, the strength of the handling property can be increased. However, since the filter surface and the handling surface are in the same plane on the back surface side of the recess, it is in a state in which it is easy to contact the filter portion in the work. The filter part may be damaged or broken.

  Moreover, although the filter hole is formed by etching, the thickness of the plate is generally limited to about 10 to 20 μm in the etching of stainless steel or resin. If it is thinner than that, it may be damaged due to the cleaning pressure at the time of cleaning the resist solution during the etching process or the slight breakage of the constituent members, resulting in poor filter manufacturing yield and high cost.

  In the case of a small opening as in Patent Document 3, it may be sufficient to arrange a single grating portion at the center. However, in the line-type inkjet recording head corresponding to A4 or A3 wide size, the grating portion is not Not enough. However, when the number of the lattice portions is increased, the transmission area of the filter is reduced and the pressure loss is increased. On the other hand, if the number of the lattice portions is too small, there are disadvantages such as poor handling of the filter.

  An object of the present invention is to eliminate the disadvantages of the prior art as described above, improve the handling by improving the rigidity of the common supply flow path forming member, and have a stable discharge characteristic and a highly reliable liquid droplet discharge head. Another object of the present invention is to provide a droplet discharge device and an image forming apparatus including the same.

In order to achieve the above object, the first present invention provides:
A plurality of nozzles arranged in a row, a pressure chamber provided in communication with each nozzle individually, a pressure generating means for changing the pressure in the pressure chamber, and a communication with each pressure chamber individually And a common supply flow path forming member that forms a common supply flow path that communicates with the individual supply flow paths and the individual supply flow paths,
The liquid supplied through the common supply flow channel is introduced into the pressure chambers through the individual supply flow channels, and the pressure generation means applies pressure fluctuations to the pressure chambers. The target is a droplet discharge head that lands on the surface.

And a filter is provided in the common supply flow path of the common supply flow path forming member,
In the common supply flow path with the filter in between, the upstream common supply flow path formed upstream of the filter in the liquid flow direction, and the downstream common supply formed downstream of the filter in the liquid flow direction Divided into channels,
In the upstream common supply flow path and the downstream common supply flow path, an upstream lattice portion and a downstream lattice portion extending in a direction perpendicular to the nozzle arrangement direction are respectively spaced along a nozzle arrangement direction. In this case, a plurality of each is formed.

In order to achieve the above object, the second aspect of the present invention provides a liquid tank that stores a liquid to be discharged, a liquid droplet discharge head, and a liquid supply that supplies the liquid stored in the liquid tank to the liquid droplet discharge head. A droplet discharge apparatus for landing a droplet discharged from the droplet discharge head on a deposition medium,
The droplet discharge head is the droplet discharge head of the first invention.

  To achieve the above object, according to a third aspect of the present invention, in the image forming apparatus, the liquid is an image forming ink, the adherend medium is a recording medium, and the liquid droplet ejection apparatus according to the second aspect of the present invention is provided. It is characterized by having.

  The present invention is configured as described above, and can provide a droplet ejection head having stable ejection characteristics and high operational reliability, a droplet ejection apparatus including the droplet ejection apparatus, and an image forming apparatus.

1 is an exploded perspective view of a main part of an ink jet recording head according to Example 1 of the invention. FIG. It is sectional drawing on the FIG. 1A-A line in the state which assembled the inkjet recording head. It is sectional drawing on the FIG. 2B-B line. It is the top view which looked at each component of the inkjet recording head from the nozzle side. It is the top view which looked at each component of the inkjet recording head from the piezoelectric actuator side. (A), (b) is an enlarged plan view which shows the example of arrangement | positioning of the nozzle in an inkjet recording head. It is a figure showing the relationship between nozzle mounting density and a lattice part ratio. It is a figure showing the relationship between the arrangement | positioning space | interval of a grating | lattice part, and the pressure loss in the filter at that time. (A), (b) is a figure which compares and shows the flow of the ink in the common supply flow path in an Example and a comparative example. (A), (b) is a figure which compares and shows the flow of the thermal convection in the inkjet recording head of an Example and a comparative example. It is sectional drawing of the inkjet recording head which concerns on Example 2 of this invention. FIG. 4 is a plan view (a) of the diaphragm plate viewed from the nozzle side of the ink jet recording head, and a plan view (b) of the diaphragm plate viewed from the piezoelectric actuator side. FIG. 6 is an exploded perspective view of an ink jet recording head according to Example 3 of the invention. It is sectional drawing which cut | disconnected the inkjet recording head in the direction orthogonal to a nozzle arrangement direction. It is the schematic diagram which saw through the inkjet recording head from the nozzle formation surface side. It is the schematic diagram which saw through the inkjet recording head from the side surface of a nozzle arrangement direction. It is sectional drawing which cut | disconnected the inkjet recording head which concerns on Example 4 of this invention in the direction orthogonal to a nozzle arrangement direction. It is the schematic diagram which saw through the inkjet recording head which concerns on Example 5 of this invention from the nozzle formation surface side. It is the schematic diagram which saw through the inkjet recording head from the side surface of a nozzle arrangement direction. 1 is a perspective view of an image forming apparatus in which an ink jet recording head according to each embodiment of the present invention can be mounted.

  Next, each embodiment of the present invention will be described with reference to the drawings.

  1 to 6 are diagrams for explaining the ink jet recording head according to the first embodiment of the present invention. FIG. 1 is an exploded perspective view of the main part of the ink jet recording head. FIG. 2 is an assembly of the ink jet recording head. FIG. 3 is a sectional view taken along the line A-A in FIG. 1A-A, FIG. 3 is a sectional view taken along the line B-B in FIG. 2, FIG. 4 is a plan view of each component of the inkjet recording head viewed from the nozzle side, and FIG. FIG. 6A and FIG. 6B are enlarged plan views showing examples of arrangement of nozzles when each component of the ink jet recording head is viewed from the piezoelectric actuator side.

  In these drawings, reference numeral 2 denotes an orifice plate in which a plurality of nozzles 1 are formed in a row. The processing accuracy of the opening shape of the nozzle 1 greatly affects the ink ejection characteristics of the ink jet recording head. In order to suppress these nozzle accuracy variations among a plurality of nozzles 1, the manufacturing method of the orifice plate 2 is required to have high processing accuracy. For this reason, the orifice plate 2 is formed by a stainless precision pressing method, a laser processing method, a nickel electroforming method, or the like.

  Reference numeral 5 denotes a restrictor plate in which a pressure chamber 3 and an individual supply channel 4 that controls the inflow of ink into the pressure chamber 3 by connecting the pressure chamber 3 and the common supply channel 8 are formed. The pressure chamber 3 and the individual supply channel 4 are arranged so as to correspond to the nozzle 1. The restrictor plate 5 is made of stainless steel, silicon etching or precision pressing.

  Reference numeral 10 denotes a diaphragm in which a diaphragm 6 for efficiently transmitting the displacement of the piezoelectric actuator 17 to the pressure chamber 3 and a filter 7 for removing dust and the like in the ink flowing into the individual supply channel 4 from the common supply channel 8 are formed. It is a plate. The diaphragm 6, the filter 7 and the diaphragm plate 10 are formed as a single unit.

  Reference numeral 14 denotes a housing in which the frame-side common supply flow path 11 and the actuator insertion opening 12 are formed, and holds and fixes the aforementioned plates 2, 5, and 10. The housing 14 is formed by cutting stainless steel or the like, and is formed with an ink introduction passage 13 that guides ink from an ink tank (not shown) to the frame-side common supply passage 11.

  As shown in FIG. 2, a heater 20 is attached to one side surface of the wall portion that defines the frame-side common supply flow path 11 of the housing 14. As shown in FIG. 1, the heater 20 extends along the arrangement direction of the nozzles 1 and over almost the entire length of the frame-side common supply flow path 11.

  As described above, in recent years, the demand for UV ink is increasing in the field of printing. Many of these UV inks have a relatively high viscosity at room temperature. In order to discharge high-viscosity ink such as UV ink from the nozzle 1, means for heating the ink in advance using the heater 20 to reduce the viscosity is used.

  In this embodiment, one piezoelectric actuator insertion opening 12 is formed larger as shown in FIG. 1. However, a partition may be provided for each piezoelectric vibrator 15 to increase the rigidity of the piezoelectric actuator insertion opening 12. By increasing the rigidity, the mechanical factor of crosstalk: mutual interference between channels can be reduced.

  Reference numeral 17 denotes a piezoelectric actuator including the piezoelectric vibrator 15 and the fixing member 16. One end of the piezoelectric vibrator 15 is fixed to one end face of the fixing member 16 using an adhesive, and the other end (free end) of the piezoelectric vibrator 15 is joined to the diaphragm 6. An electric signal is inputted to the individual electrode pattern and the common electrode pattern of the piezoelectric actuator 17 via an FPC (not shown), and a displacement is caused at the free end of the piezoelectric vibrator 15. This displacement is transmitted to the pressure chamber 3 via the vibration plate 6, and the volume of the pressure chamber 3 expands and contracts accordingly, thereby causing a pressure fluctuation in the pressure chamber 3, and the ink droplets from the nozzle 1. Are ejected and landed on a recording medium (not shown) to form an image.

Next, a specific configuration around the filter 7 will be described.
As shown in FIG. 3, the filter 7 in the diaphragm plate 10 is provided at a substantially intermediate position in the thickness direction of the diaphragm plate 10 and is provided between the upstream lattice portion 9a and the downstream lattice portion 9b. In this specification, “upstream side” and “downstream side” mean that ink passes from the frame-side common supply channel 11 to the common supply channel 8, the individual supply channel 4, and the pressure chamber 3 in the ink jet recording head. Thus, with respect to the flow discharged from the nozzle 1, the frame-side common supply flow path 11 side is referred to as “upstream side”, and the individual supply flow path 4 (pressure chamber 3) side is referred to as “downstream side”.

  As shown in FIG. 1, both the upstream lattice portion 9 a and the downstream lattice portion 9 b extend in a direction orthogonal to the arrangement direction of the nozzles 1, and a plurality of them are formed at equal intervals along the arrangement direction of the nozzles 1. Has been.

  In the case of the present embodiment, the upstream lattice portion 9a and the downstream lattice portion 9b are provided in the same position in a pair of upper and lower sides. The upstream lattice portion 9a and the downstream lattice portion 9b are integrally formed continuously with the filter 7 as shown in FIGS. 2 and 3 and with the diaphragm plate 10 as shown in FIG. The installation interval of the upstream lattice portion 9a (downstream lattice portion 9b) will be described later.

  The filter 7 has a thickness of about 3 μm to 20 μm, and a large number of filter holes 7a (see FIG. 6) having a diameter D smaller than the minimum dimension of the flow path (inner diameter of the nozzle 1) are formed close to each other. As shown in FIG. 6A, the filter holes 7a may be arranged in a staggered manner as shown in FIG. 6A. Alternatively, the filter holes 7a may be arranged in a vertical and horizontal lattice shape as shown in FIG. 6B. Good. In the staggered arrangement shown in FIG. 6A, the ratio of the total area of the filter holes 7a to the total area of the filter (the total area of the filter holes / the entire area of the filter) as compared with the lattice arrangement shown in FIG. 6B. It is preferable that a so-called aperture ratio can be increased. Since the aperture ratio greatly affects the pressure loss, it is better to make it as large as possible.

  Reference numeral 7b in the figure is a connecting portion provided between the filter hole 7a and the filter hole 7a. The width of the connecting portion 7b is 10 μm or more in order to ensure the strength that can be withstood by applying the channel pressure to the filter 7 and to prevent the filter holes from being connected due to manufacturing variations. There is a need to.

  When the diaphragm plate 10 having the filter 7 is manufactured by electroforming nickel, it is possible to obtain the filter 7 that is thinner and has less pressure loss. Further, the filter 7 can be formed by etching a stainless material or the like.

  Thus, it is desirable that the diaphragm plate 10 is a material having good thermal conductivity and excellent corrosion resistance, such as nickel or stainless steel. When the diaphragm plate 10 is made of a material having good thermal conductivity, the grids 9a and 9b are provided in a dispersed manner, so that heat from the heater 20 is efficiently transmitted to each channel, so that the heater 20 is attached. The problem that the temperature increases only in the vicinity is solved. Then, the viscosity of the ink supplied to each channel (pressurizing chamber 3) can be made uniform, and the ink jet recording can be provided with little variation in ejection characteristics.

  Further, in order to efficiently transmit the displacement from the piezoelectric actuator 17, it is preferable that the diaphragm 6 is also thin. By making the thickness of the diaphragm 6 and the thickness of the filter 7 substantially the same, the function of the conventional diaphragm can be achieved. A thin diaphragm plate having a filter and a plate having a filter laminated on each other can be handled as the same part. In the filter formation region, lattice portions 9a and 9b having substantially the same thickness as the diaphragm plate 10 are formed at predetermined intervals.

  FIG. 7 is a diagram illustrating the relationship between the nozzle mounting density and the lattice portion ratio. As shown in the figure, when the width dimension of the pressure chamber 3 in the nozzle arrangement direction is Wa, and the width dimension of the grid portion 9 in the nozzle arrangement direction is Wb, the grid portion ratio can be expressed as Wb / Wa. As shown in FIG. 3, the width dimension in the nozzle arrangement direction of the partition walls 4 a that partition each pressure chamber 3 (individual supply flow path 4) is the same as the width dimension Wb in the nozzle arrangement direction of the lattice portion 9.

  In the upper part of FIG. 7, the lattice ratio is A when the width of the pressure chamber 3 is Wa and the width of the lattice 9 is Wb. In the middle of the figure, when the width dimension of the pressure chamber 3 is Wa / 2 and the width dimension of the grating portion 9 is Wb as it is, the grating portion ratio is 2A. Further, in the lower part of the figure, when the width dimension of the pressure chamber 3 is Wa / 4 and the width dimension of the grating part 9 is Wb as it is, the grating part ratio is 4A. As shown in the figure, since the nozzle 1 is arranged at the center position of the pressure chamber 3, the upper part of the figure is a low nozzle density nozzle arrangement, and the lower part of the figure is a high nozzle density nozzle arrangement.

  As shown in FIG. 7, it is necessary to reduce the pressure chamber 3 in order to achieve high-density mounting. However, the filter 7 is required to have a handling strength and a strength that can withstand the adhesive pressure when the plates are laminated. For this reason, the width of the lattice portion 9 cannot be reduced to be equal to the ratio of the pressure chambers.

  FIG. 8 is a diagram showing the relationship between the arrangement interval of the lattice portions 9 and the pressure loss at the filter 7 at that time. The pressure loss ratio on the vertical axis indicates the case where the lattice portions 9 are arranged for each partition 4a (one channel) that partitions and forms each pressure chamber 3 shown in FIG. 3 (that is, the number of lattice portions 9 is the number of partitions 4a installed). 1), the ratio (pressure loss under the lattice arrangement condition / pressure loss when the lattice portion is arranged for each channel) is displayed. The lattice portion position on the horizontal axis indicates the arrangement interval of the lattice portions. For example, when the lattice portion position (interval of arrangement of the lattice portions) is 4, the lattice portion 9 and the adjacent lattice portion 9 as shown in FIG. 4 shows that there are four individual supply channels 4 (four channels).

  The curve A in the figure is a characteristic curve showing the relationship between the lattice portion position (lattice interval) and the pressure loss ratio when the lattice portion ratio is 0.3 and the curve B is 0.6. It is.

  As is clear from this figure, the pressure loss ratio is still high when the grid position (lattice arrangement interval) is two flow paths in both curves A and B, but the grid position (lattice arrangement interval) is 4. It can be seen that the pressure loss is reduced due to the interval of 8 → 16 flow paths. In addition, as shown in the figure, even if the grid part position (lattice arrangement interval) exceeds 16 flow paths (the grid part positions are 32, 64, 128, and 192 flow paths), the effect of reducing pressure loss is Almost no change is made, but rather, the number of installed grid portions is reduced as a whole, and accordingly, effects such as an increase in the mechanical strength of the filter portion due to the installation of the grid portions and a uniform distribution of heat from the heater cannot be obtained sufficiently. For this reason, the position of the lattice portion (arrangement interval of the lattice portion) is preferably restricted to a range of 4 to 16 flow paths.

  Further, as a result of the examination of the lattice portion ratio, as the lattice portion ratio increases, the total area of the filter can be increased and the pressure loss can be reduced. The part ratio is preferably 0.3 or more.

  Further, the grid portions 9a and 9b are periodically arranged on both surfaces of the filter 7 at a predetermined interval, and the upper and lower sides of the filter 7 are formed to be concave portions, thereby improving the handleability of the filter 7 portion. .

  Each downstream lattice portion 9b that partitions the filter 7 faces the partition wall portion 4a that partitions and forms the pressure chamber 3, and the contact surfaces of the partition wall portion 4a and the lattice portion 9b are integrally bonded with an adhesive.

  FIGS. 9A and 9B are diagrams showing a comparison of ink flows in the common supply flow path 8 in the example and the comparative example. FIG. 5A schematically shows the flow of ink in the ink jet recording head according to the first embodiment, and FIG. 5B shows the ink jet recording head of the comparative example in which the downstream side lattice portion 9b is not provided. An ink flow is schematically shown.

  In the case where the downstream side lattice portion 9 b is not provided as shown in FIG. 5B, a large area space that remains the common supply flow path 8 is formed under the filter 7. Therefore, there is a sudden change in the cross-sectional area before and after passing through the filter 7, and a turbulent flow 18c is generated, which causes pressure loss. Further, with the generation of the turbulent flow 18c, stagnation occurs in the ink flow in the vicinity of the filter 7 and bubbles are generated, which adversely affects the ink ejection characteristics.

  On the other hand, as shown in FIG. 5A, the upstream lattice portion 9a and the downstream lattice portion 9b are provided at the same position on the upstream side and downstream side of the filter 7 as a boundary. The side is divided into a plurality of upstream ink chambers 8a, and the downstream side is divided into a plurality of downstream ink chambers 8b. Therefore, the cross-sectional area before and after transmission through the filter is the same. The ink flow 18a flowing into the upstream ink chamber 8a passes through the filter 7 and passes through the downstream ink chamber 8b as it is as the ink flow 18b. Accordingly, the downstream side lattice portion 9b also functions as an ink rectifying plate, and problems such as the generation of the turbulent flow 18c, the stagnation of the flow in the vicinity of the filter 7, or the generation of bubbles do not occur.

  10A and 10B are diagrams showing a comparison of thermal convection flows in the inkjet recording heads of the example and the comparative example. FIG. 5A schematically shows thermal convection in the inkjet recording head according to the first embodiment, and FIG. 4B shows thermal convection in the comparative inkjet recording head in which the downstream side lattice portion 9b is not provided. Is schematically shown.

  As shown in FIG. 2, in an ink jet recording head in which ink is heated by a heater 20 to reduce the viscosity and eject ink, when the ink is ejected in a large amount per unit time for high speed printing, the vicinity of the ink introduction unit 13 is sufficient. The ink temperature is low. On the other hand, since the ink is heated by the heater 20 in the vicinity of the frame-side common supply channel 11, the ink temperature on the common supply channel 11 side is high.

  Therefore, in both FIGS. 10A and 10B, a relatively large heat convection 21a is generated in the frame-side common supply flow path 11, and the comparison is made in the upstream common supply flow path 8a divided by the next upstream lattice portion 9a. Small thermal convection 21b is generated.

  In the case where the downstream side lattice portion 9 b is not provided as shown in FIG. 5B, a large area space that remains the common supply flow path 8 is formed under the filter 7. For this reason, the ink temperature is low near the ink introduction portion 13 and the ink temperature is high near the frame-side common supply flow path 11 to generate a relatively large heat convection 21c. When the thermal convection 21c occurs in the common supply flow path 8 in such a large space, a temperature distribution is generated in the common supply flow path 8, thereby changing the viscosity of the ink supplied to each pressure chamber 3, and the nozzles. There is a problem in that the discharge performance between the units varies.

  On the other hand, as shown in FIG. 9A, a plurality of downstream lattice portions 9b are also provided on the downstream side of the filter 7 and divided into a plurality of downstream ink chambers 8b, whereby each downstream ink chamber 8b. The heat convection 21c generated in the inside becomes smaller than that shown in FIG. Therefore, it is possible to provide an ink jet recording head in which the ink viscosity distribution is reduced and the variation in ejection performance between the nozzles 1 is small.

  In this embodiment, as shown in FIG. 1, the wrist reactor plate 5 in which the pressure chamber 3 and the individual supply flow path 4 are integrally formed is used, but the chamber plate in which the pressure chamber 33 is formed as shown in FIG. 34 and the wrist reactor plate 36 in which the wrist reactor 35 is formed can be used in an overlapping manner.

  11 is a cross-sectional view of an ink jet recording head according to Embodiment 2 of the present invention, FIG. 12A is a plan view of a diaphragm plate viewed from the nozzle side, and FIG. 11B is a plan view of the diaphragm plate viewed from the piezoelectric actuator side. FIG.

  The installation positions of the upstream lattice portion 9a and the downstream lattice portion 9b that partition the filter 7 are different on the projection plane. As shown in FIG. 11, the upstream lattice portions 9a are arranged at intervals of the downstream lattice portions 9b. It is located in the middle. In the case of this embodiment as well, the arrangement interval between the upstream lattice portions 9a and the arrangement interval between the downstream lattice portions 9b are equal. Further, the downstream side lattice portion 9b and the partition wall 4a forming the pressure chamber 3 are bonded with an adhesive.

  In addition, as shown in FIG. 11, the arrangement | positioning space | interval of the upstream grid | lattice part 9a (downstream grid | lattice part 9b) is set for every multiple flow paths like 4, 6, 8,. If the design is made to correspond to the partition 4a, the upstream lattice portion 9a and the partition 4a are arranged on the same vertical line, and the pressure loss caused by shifting the installation positions of the upstream lattice portion 9a and the downstream lattice portion 9b from each other. There is virtually no increase. Also in the present embodiment, the width dimension in the nozzle array direction of the upstream lattice part 9a and the downstream lattice part 9b is substantially the same as the width dimension in the nozzle array direction of the partition walls 4a that partition the individual supply flow paths 4. ing.

  By providing the upstream lattice portion 9a and the downstream lattice portion 9b with respect to the filter 7 so as to be shifted from each other as in the present embodiment, the area of the thick portion joined to the lattice portion in the filter 7 can be doubled. The mechanical strength of the filter 7 can be increased, and the risk of breakage during work can be reduced. If the lattice portions 9 are simply provided at twice the arrangement pitch to obtain the same effect, the transmission area of the filter 7 decreases and the pressure loss increases. Therefore, according to this embodiment, it is possible to improve the handling performance while suppressing an increase in pressure loss due to the arrangement of the lattice portion 9.

  Also in this embodiment, the effect of suppressing the turbulence of the ink flow described with reference to FIG. 9 and the effect of reducing the distribution of the ink viscosity described with reference to FIG. 10 can be exhibited.

  Next, an ink jet recording head according to Example 3 will be described with reference to FIGS. 13 is an exploded perspective view of the ink jet recording head according to the present embodiment, FIG. 14 is a cross-sectional view of the ink jet recording head cut in a direction orthogonal to the nozzle arrangement direction, and FIG. FIG. 16 is a schematic diagram seen through from the side surface in the nozzle arrangement direction.

The overall configuration of the ink jet recording head according to the present embodiment will be described with reference to FIG.
An orifice plate 32 has a plurality of nozzles 31 formed in a row. Reference numeral 34 denotes a chamber plate in which a pressure chamber 33 is formed, and the pressure chamber 33 is disposed so as to correspond to the nozzle 31.

  Reference numeral 36 denotes a restrictor plate in which a restrictor 35 is formed, and the restrictor 35 is disposed so as to correspond to the pressure chamber 3. Reference numeral 39 denotes an elastic diaphragm plate in which a diaphragm 37 and a filter 38 are formed. The chamber plate 34, the restrictor plate 36, and the diaphragm plate 39 are made by a stainless steel etching method, a nickel electroforming method, or a precision press method.

  Reference numeral 42 denotes a manifold plate in which a plate-side common supply channel 40 and a plate-side insertion opening 41 are formed. The manifold plate 42 is made of a material having good thermal conductivity and excellent corrosion resistance, and is made by, for example, a stainless steel etching method. In the plate-side common supply flow path 40, a lattice portion 43 is formed integrally with the manifold plate 42 so as to cross the plate-side common supply flow path 40 in a direction orthogonal to the nozzle arrangement direction for each channel.

  The lattice portion 43 is provided so as to face a restrictor partition wall 44 (see FIG. 13) that partitions each restrictor 35 and a pressure chamber partition wall 45 (see FIGS. 13 and 16) that partitions the pressure chamber 33. ing. Further, as shown in FIGS. 13 and 16, the lattice portion 43 is not provided at an intermediate position in the thickness direction of the manifold plate 42, but is provided so as to be offset toward the housing 46 described later. In the assembled state, a gap having the same area as the plate-side common supply flow path 40 is formed between the lattice portion 43 and the filter 38.

  In this way, to manufacture the manifold plate 42 having the lattice portion 43 on one side and having a concave section, the manifold plate half without the lattice portion 43 on the pressure chamber 33 side, and the lattice portion 43 on the housing 46 side. It is also possible to manufacture the manifold plate 42 by overlapping the manifold plate halves having In this case, the manifold plate 42 can be easily manufactured.

  A housing 46 is formed with a frame-side common supply channel 47 and a frame-side insertion opening 48, and holds and fixes the plates 32, 34, 36, 39, and 42 described above. The housing 46 is formed by cutting a stainless material or the like, and an ink introduction passage 49 that guides ink from an ink tank (not shown) to the frame-side common supply channel 47 is formed.

  As shown in FIG. 13, the frame-side insertion opening 48 of the housing 46 and the plate-side insertion opening 41 of the manifold plate 42 are widely opened, but a partition portion is integrally provided for each piezoelectric vibrator 52 described later. By increasing the rigidity, crosstalk: mechanical factors of mutual interference between channels can be reduced.

  As shown in FIG. 14, a heater 50 is bonded and fixed to one side surface of the partition wall that defines the plate-side common supply channel 40 of the manifold plate 42 and the frame-side common supply channel 47 of the housing 46. As shown in FIGS. 13 and 15, the heater 50 extends along the arrangement direction of the nozzles 31 and is formed over almost the entire length of the plate-side common supply channel 40 and the frame-side common supply channel 47.

  In order to discharge high-viscosity ink such as UV ink from the nozzles 31, means for preheating the ink using the heater 50 to lower the viscosity is used. Although it is possible to attach the heater 50 from the outside of the manifold plate 42 and the housing 46, the manifold plate 42 and the housing 46 are inserted as shown in FIG. The heater 50 is affixed from the openings 41 and 48 side.

  A piezoelectric actuator 51 includes a piezoelectric vibrator 52 and a fixing member 53. One end of the piezoelectric vibrator 52 is fixed to one end surface of the fixing member 53 using an adhesive, and the other end (free end) of the piezoelectric vibrator 52 is joined to the vibration plate 37. An electric signal is input to the individual electrode pattern and the common electrode pattern of the piezoelectric actuator 51 via an FPC (not shown), and the free end of the piezoelectric vibrator 52 is displaced. This displacement is transmitted to the pressure chamber 33 via the vibration plate 37, and the volume of the pressure chamber 33 expands and contracts accordingly, whereby ink droplets are ejected from the nozzle 31 and an image is displayed on a recording medium (not shown). Form.

  As shown in FIG. 14, when the heater 50 is attached to one side of the partition wall of the common supply passages 40 and 47 of the manifold plate 42 and the housing 46, there is a temperature distribution in a direction orthogonal to the nozzle 31 arrangement direction.

  Therefore, in this embodiment, the lattice portion 43 extending in the direction crossing the common supply flow path 40, that is, the direction orthogonal to the nozzle arrangement direction, is formed in the manifold plate 42 in the common supply flow path 40 of the manifold plate 42. Provided integrally. Since the manifold plate 42 is made of a material having good thermal conductivity, heat is transferred uniformly and quickly in the direction perpendicular to the nozzle arrangement direction for each channel by the action of the lattice portion 43, and the ink Temperature distribution is almost eliminated, and the ink viscosity can be made uniform.

  Although not shown, a thermistor for detecting the temperature and controlling the ink temperature is attached in the vicinity of the common supply flow path 47 (40). As a result, the ink temperature in the common supply channels 47 and 40 can be controlled to be constant, and an ink jet recording head with little variation in ejection characteristics can be provided for each channel.

  In the present embodiment, as shown in FIG. 13, the lattice portion 43 is provided on the manifold plate 42, but it is also possible to form a lattice portion extending in a direction orthogonal to the arrangement direction of the nozzles 31 in the formation region of the filter 38. It is.

  In this embodiment, as shown in FIG. 13, the chamber plate 34 in which the pressure chambers 33 are formed and the wrist reactor plate 36 in which the wrist reactors 35 are formed are separated. However, as shown in FIG. It is also possible to use a wrist reactor plate 5 in which the supply flow path 4 is integrally formed.

  Next, FIG. 17 shows a cross-sectional view of the ink jet recording head according to Example 4 cut in a direction orthogonal to the nozzle arrangement direction.

  In this embodiment, as shown in the figure, the common supply flow path 47 of the housing 46 is also provided with a multistage grid portion 54 extending in a direction crossing the common supply flow path 47, that is, a direction orthogonal to the nozzle arrangement direction. Provided. The housing 46 is also made of a material having good thermal conductivity such as stainless steel.

  Thus, by providing the grid portion 54 also in the common supply flow path 47 of the housing 46, the heat transfer efficiency for the ink can be further increased. Even if the ejection drive frequency is increased to increase the printing speed and the ink supply flow rate is increased, the ink temperature can be sufficiently equalized and ink with uniform viscosity can be supplied to each channel, thus increasing the speed. An ink jet recording head that can be applied and has little variation in ejection characteristics can be provided.

  Next, an ink jet recording head according to Example 5 will be described with reference to FIGS. FIG. 18 is a schematic view of the inkjet recording head seen through from the nozzle forming surface side, and FIG. 19 is a schematic view of the inkjet recording head seen through from the side in the nozzle arrangement direction.

  In the third embodiment, the lattice portion 43 is provided at a position facing the pressure chamber partition wall 45 as shown in FIG. 16, but in this embodiment, the lattice portion 43 is provided in each pressure chamber 33 (each reductor 33) as shown in FIG. 35) at a position facing the center position.

  Also in the case of this embodiment, the lattice portion 43 is not provided at the intermediate position in the plate thickness direction of the manifold plate 42 but is provided so as to be offset toward the housing 46 side, and in the assembled state of the ink jet recording head, A wide space portion of the plate-side common supply flow path 40 is formed between the lattice portion 43 and the filter 38.

  FIG. 20 is a perspective view of an ink jet printer in which the ink jet recording head according to each of the embodiments can be mounted.

  The ink jet recording head 60 is reciprocally moved on guide shafts 61 and 61 extending from the frame by forward and reverse rotation of a driving motor connected to a timing belt (not shown), and the recording medium 63 conveyed by the conveying roller 62. Images such as letters and figures are printed by ejecting ink droplets on the top.

  Ink supply to the ink jet recording head 60 is sent from the main ink tank 64 to the sub ink tank 66 via the flexible tube 65 and further supplied to the ink jet recording head 60 via the flexible tube 65. Although not shown, a supply pump is provided in the middle of the flexible tube 65.

  The head maintenance unit 67 is a cap 68 to prevent ink from drying or adhesion of foreign matter from the nozzle 1 (31) of the ink jet recording head 60 when not printing, or although not shown, ink attached to the nozzle surface, etc. A wiper blade or the like is provided for removing water. The cap 68 is also used as a suction cap at the time of a purge operation performed for the purpose of filling ink from the sub ink tank 66 into the ink jet recording head 60 or removing bubbles remaining in the ink jet recording head 60. The

  Cyan, magenta, yellow, and black inks are individually supplied to and discharged from each nozzle of the inkjet recording head 60, and a color image can be formed by superimposing the ink on each color on the recording medium 63.

  In this embodiment, a liquid droplet ejection apparatus according to the present invention includes a liquid tank such as a main ink tank 64 and a sub ink tank 66 for storing liquid to be ejected, a liquid droplet ejection head composed of an ink jet recording head 60, and the liquid tank. Liquid supply means including a flexible tube 65 and a supply pump for supplying the liquid stored in the liquid droplet ejection head to the liquid droplet ejection head.

Next, the function and effect of each claim of the present invention will be described as follows.
According to the invention described in claim 1, by forming a plurality of lattice portions in the common supply flow path, the rigidity of the common supply flow path forming member such as the diaframe plate and the manifold plate can be increased. Can improve the performance.

  According to the third and fourth aspects of the present invention, even if a plurality of lattice portions are formed, an increase in pressure loss can be suppressed, the flow of liquid in the droplet discharge head is smooth, and the droplet discharge characteristics are stable. doing.

  According to the inventions of claims 8 and 9, even if the heater is provided on one side surface, the thermal conductivity through the plurality of lattice portions is good, and the temperature of the liquid can be kept uniform, Even with a liquid having a high viscosity at room temperature such as an ultraviolet curable liquid, the viscosity can be lowered and the droplet discharge characteristics are stable.

  According to the second aspect of the present invention, since the common supply flow path forming member, the filter, the upstream lattice portion, and the downstream lattice portion are integrally formed, the rigidity of the filter forming region is increased, and the durability of the filter is increased. The service life becomes longer and the handling property of the common supply flow path forming member is good.

  According to the invention described in claim 5, since the upstream lattice portion and the downstream lattice portion are arranged on substantially the same line along the liquid flow direction from the common supply flow path to the individual supply flow path, The increase in pressure loss is suppressed, the flow of liquid in the droplet discharge head is smooth, and the droplet discharge characteristics are stable.

  According to the seventh aspect of the present invention, since the upstream side lattice portion and the downstream side lattice portion are provided at positions corresponding to the partition walls for every 4 to 16 flow paths of the individual supply flow paths, there is no lattice portion. Thus, almost the same filter permeation performance as when the filter is provided over the entire common supply flow path can be obtained. Furthermore, handling strength during handling can be increased.

  According to the tenth aspect of the present invention, there is provided a droplet discharge device having the above-described features.

  According to the eleventh aspect of the present invention, an image forming apparatus compatible with high density and high speed printing is provided.

  In the above embodiment, the case of the ink jet recording apparatus has been described. However, the present invention is not limited to this, and is used for forming an electrode film such as a color material liquid used for manufacturing a color filter of a liquid crystal display and an organic EL display. The present invention can also be applied to a droplet discharge device that discharges another liquid such as an electrode material liquid.

  1: nozzle, 2: orifice plate, 3: pressure chamber, 4: individual supply flow path, 4a: partition wall, 5: restrictor plate, 6: diaphragm, 7: filter, 7a: filter hole, 7b: connecting portion, 8: Common supply flow path, 8a: Upstream common supply flow path, 8b: Downstream common supply flow path, 9: Lattice portion, 9a: Upstream lattice portion, 9b: Downstream lattice portion, 10: Diaphragm plate, 11 : Frame side common supply flow path, 12: Actuator insertion opening, 13: Ink introduction passage, 14: Housing, 15: Piezoelectric vibrator, 16: Fixing member, 17: Piezoelectric actuator, 20: Heater, 31: Nozzle, 32 : Orifice plate, 33: Pressure chamber, 35: Restrictor, 36: Restrictor plate, 37: Vibration plate, 38: Filter, 39: Diaphragm plate, 40: On both sides of plate Supply channel 41: Plate side insertion opening 42: Manifold plate 43: Grid part 44: Restrictor partition 45: Pressure chamber partition 46: Housing 47: Frame side common supply channel 48: Frame Side insertion opening, 49: ink introduction passage, 50: heater, 51: piezoelectric actuator, 52: piezoelectric vibrator, 53: fixing member, 54: lattice portion, 60: inkjet recording head, 61: guide shaft, 62: transport Roller, 63: recording medium, 64: main ink tank, 65: flexible tube, 66: sub ink tank, 67: head maintenance section, 68: cap.

Japanese Patent No. 40000695 JP 2006-305767 A JP-A-2005-161617

Claims (11)

A plurality of nozzles arranged in a row, a pressure chamber provided in communication with each nozzle individually, a pressure generating means for changing the pressure in the pressure chamber, and a communication with each pressure chamber individually And a common supply flow path forming member that forms a common supply flow path that communicates with the individual supply flow paths and the individual supply flow paths,
The liquid supplied through the common supply flow channel is introduced into the pressure chambers through the individual supply flow channels, and the pressure generation means applies pressure fluctuations to the pressure chambers. In the droplet discharge head that lands on
A filter is provided in the common supply flow path of the common supply flow path forming member,
In the common supply flow path with the filter in between, the upstream common supply flow path formed upstream of the filter in the liquid flow direction, and the downstream common supply formed downstream of the filter in the liquid flow direction Divided into channels,
In the upstream common supply flow path and the downstream common supply flow path, an upstream lattice portion and a downstream lattice portion extending in a direction perpendicular to the nozzle arrangement direction are respectively spaced along a nozzle arrangement direction. And a plurality of droplet discharge heads formed respectively.   2. The droplet discharge head according to claim 1, wherein the common supply flow path forming member, the filter, the upstream lattice portion, and the downstream lattice portion are integrally formed.   3. The droplet discharge head according to claim 1, wherein a thickness of the upstream lattice portion and a downstream lattice portion in a nozzle arrangement direction is substantially equal to a thickness of a partition wall defining the individual supply flow path in a nozzle arrangement direction. A droplet discharge head having the same size.   4. The liquid droplet ejection head according to claim 1, wherein the upstream lattice portion and the downstream lattice portion are arranged along the flow direction of the liquid from the common supply flow channel to the individual supply flow channel. A droplet discharge head, which is disposed at a position corresponding to   5. The droplet discharge head according to claim 1, wherein the upstream lattice portion and the downstream lattice portion are substantially along a flow direction of the liquid from the common supply flow path to the individual supply flow path. A droplet discharge head characterized by being arranged on the same line.   5. The droplet discharge head according to claim 1, wherein the upstream lattice portion is disposed at an intermediate position of a lattice interval of the downstream lattice portion. 6.   7. The liquid droplet ejection head according to claim 1, wherein the upstream lattice portion and the downstream lattice portion are provided at positions corresponding to the partition walls of the individual supply flow paths 4 to 16. A droplet discharge head characterized by comprising:   8. The droplet discharge head according to claim 1, wherein the common supply flow path forming member is made of a material having good thermal conductivity, and the nozzle is formed on one side surface of the common supply flow path forming member. A heater extending along the arrangement direction is attached, and the heat generated from the heater passes through the common supply flow path through the common supply flow path forming member, the upstream lattice section, and the downstream lattice section. A droplet discharge head characterized by being configured to be supplied to a liquid.   9. The droplet discharge head according to claim 8, wherein the liquid is an ultraviolet curable liquid. A liquid tank that stores a liquid to be discharged; a liquid droplet discharge head; and a liquid supply unit that supplies the liquid stored in the liquid tank to the liquid droplet discharge head, and the liquid droplets discharged from the liquid droplet discharge head In a droplet discharge device that lands on a deposition medium,
10. A liquid droplet ejection apparatus, wherein the liquid droplet ejection head is the liquid droplet ejection head according to claim 1.   An image forming apparatus comprising the liquid droplet ejection apparatus according to claim 10, wherein the liquid is an image forming ink, and the deposition medium is a recording medium.