Patent Description:
Inkjet printers and inkjet plotters that utilize inkjet recording methods are known as printing apparatuses. In recent years, inkjet recording systems have also been widely used in industrial applications such as forming electronic circuits, manufacturing color filters for liquid crystal displays, manufacturing organic EL displays, and the like.

In such inkjet printing apparatuses, a liquid discharge head for discharging liquid is mounted. A thermal method and a piezoelectric method are commonly known in this type of liquid discharge head. The liquid discharge head of the thermal method includes a heater as a pressurizing means in an ink channel, heats and boils ink by using the heater, and pressurizes and discharges the ink by air bubbles generated in the ink channel. The liquid discharge head of the piezoelectric type causes a wall of a part of the ink channel to be bent and displaced by a displacement element to mechanically pressurize and discharge the ink in the ink channel.

In addition, examples of such a liquid discharge head include a serial type that performs recording while the liquid discharge head is being moved in a direction (main scanning direction) orthogonal to a transport direction (sub-scanning direction) of a recording medium, and a line type that performs recording on a recording medium transported in the sub-scanning direction in a state where the liquid discharge head, which is longer than the recording medium in the main scanning direction, is fixed. The line type has an advantage that high-speed recording is possible because there is no need to move the liquid discharge head, unlike the serial type.

Such a liquid discharge head includes a head body, a drive IC configured to drive the head body, and a head cover configured to cover at least a part of the head body while housing the drive IC. In addition, in the liquid discharge head, heat generated by the drive IC is released by being brought into contact with an inner surface of the head cover covering the head body, the drive IC being housed in the head cover. The thickness of a top plate and a side plate of such a head cover is constant (see, for example, Patent Document <NUM>).

From e.g. <CIT> a liquid discharge head is known, comprising: a head body, a drive IC and a head cover, wherein the head cover includes a top plate and a first side plate that is connected to the top plate and that is in contact with the drive IC, the first side plate having a thickness that is thinner than a thickness of the top plate.

Now, in order to improve heat radiating properties in the liquid discharge head, it is conceivable to reduce a thickness of the head cover. However, in the liquid discharge head described in Patent Document <NUM>, the thickness of the top plate and the side plate of the head cover is constant, and thus, for example, when the thickness of the side plate is reduced in order to improve the heat radiating properties of the top plate and the side plate, the strength of the head cover may decrease.

An aspect of an embodiment has been made in view of the above-described problem, and an object thereof is to provide a liquid discharge head and a recording device that are capable of suppressing a decrease in strength of a head cover while improving heat radiating properties.

In order to solve said technical problem, the present invention provides a liquid discharge head with the features according to claim <NUM> and a recording device with the features according to claim <NUM>. Further preferred embodiments of the liquid discharge head are described in the dependent claims.

According to an aspect of an embodiment, it is possible to suppress a decrease in strength of the head cover while improving heat radiating properties.

Embodiments of a liquid discharge head and a recording device disclosed in the present application will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments that will be described below.

First, an overview of a recording device (hereinafter, referred to as a printer) <NUM> according to an embodiment will be described with reference to <FIG> are explanatory diagrams of the printer <NUM> according to an embodiment. Specifically, <FIG> is a schematic side view of the printer <NUM> and <FIG> is a schematic plan view of the printer <NUM>. Note that in <FIG>, a color inkjet printer is illustrated as an example of the printer <NUM>.

As illustrated in <FIG>, the printer <NUM> transports printing paper P from guide rollers 82A to transport rollers 82B. The printing paper P moves relative to a liquid discharge head <NUM>. A control unit <NUM> controls the liquid discharge head <NUM> based on image and character data, and discharges liquid toward the printing paper P. By landing droplets on the printing paper P, the printer <NUM> records images and characters on the printing paper P. A distance between the liquid discharge head <NUM> and the printing paper P is, for example, approximately <NUM> to <NUM>.

In the present embodiment, the liquid discharge head <NUM> is fixed to the printer <NUM>, and the printer <NUM> is a so-called line printer. Note that other forms of the printer <NUM> include so-called serial printers in which an operation of moving the liquid discharge head <NUM> and recording by causing the liquid discharge head <NUM> to reciprocate in a direction intersecting the transport direction of the printing paper P, for example, in a substantially orthogonal direction, and transport of the printing paper P are alternately performed.

The liquid discharge head <NUM> has a shape extending in a depth direction from the illustrated surface according to <FIG> and extending in a vertical direction according to <FIG>, and the extending direction may be described below as a longitudinal direction. In the example illustrated in <FIG>, in the printer <NUM>, a plurality of liquid discharge heads <NUM> are disposed. The liquid discharge head <NUM> is positioned such that the longitudinal direction of the liquid discharge head <NUM> is orthogonal to the transport direction of the printing paper P, and a head group <NUM> is constituted by five liquid discharge heads <NUM>. <FIG> illustrates an example in which three liquid discharge heads <NUM> are positioned frontward in the transport direction of the printing paper P, and two liquid discharge heads <NUM> are positioned rearward in the transport direction of the printing paper P, and respective centers of the liquid discharge heads <NUM> are positioned so as not to overlap with each other in the transport direction of the printing paper P.

The five liquid discharge heads <NUM> constituting the head group <NUM> are fixed to a frame <NUM> having a flat plate shape. The frame <NUM> having the flat plate shape is also positioned such that the longitudinal direction of the frame <NUM> is orthogonal to the transport direction of the printing paper P. In <FIG>, an example is illustrated in which the printer <NUM> includes four head groups <NUM>.

The four head groups <NUM> are positioned along the transport direction of the printing paper P. Liquid, for example, ink, is supplied to each of the liquid discharge heads <NUM> from a liquid tank (not illustrated). The liquid discharge heads <NUM> belonging to one head group <NUM> are supplied with ink having the same color, and four colors of ink can be printed by using the four head groups <NUM>. The colors of the ink discharged from the respective head groups <NUM> are, for example, magenta (M), yellow (Y), cyan (C), and black (K). In a case where such ink is controlled by the control unit <NUM> and printing is performed, a color image can be printed. In addition, liquid such as a coating agent may be printed in order to perform surface treatment of the printing paper P.

The number of the liquid discharge heads <NUM> mounted in the printer <NUM> may be one in a case where a single color is used and printing is performed within a range capable of being printed by one liquid discharge head <NUM>. The number of the liquid discharge heads <NUM> included in the head group <NUM> and the number of the head groups <NUM> can be appropriately changed depending on an object to be printed and printing conditions.

The printing paper P is wound on a paper feed roller 80A before use, and after passing between the two guide rollers 82A, the printing paper P passes under the plurality of frames <NUM>, passes between two transport rollers 82C and 82D, and is finally collected by a collection roller 80B.

In addition to the printing paper P, cloth in a rolled state or the like may be used as a printing target. Furthermore, instead of directly transporting the printing paper P, the printer <NUM> may have a configuration in which the printing paper P is put on a transport belt and transported. By using the transport belt, the printer <NUM> can perform printing on a sheet of paper, a cut cloth, wood, a tile, or the like as a printing target. In addition, a wiring pattern or the like of electronic equipment may be printed by discharging liquid containing electrically conductive particles from the liquid discharge head <NUM>. In addition, chemicals may be produced by discharging a chemical agent that is a predetermined amount of liquid or liquid containing a chemical agent from the liquid discharge head <NUM> toward a reaction vessel or the like.

The printer <NUM> includes a coating applicator <NUM>. The coating applicator <NUM> is controlled by the control unit <NUM>, and uniformly applies a coating agent to the printing paper P. Thereafter, the printing paper P is transported under the liquid discharge head <NUM>.

The printer <NUM> includes a head case <NUM> that houses the liquid discharge head <NUM>. The head case <NUM> is connected to the outside in a part of a portion where the printing paper P enters and exits or the like, but is a space substantially separated from the outside. As necessary, for the head case <NUM>, control factors (at least one) such as temperature, humidity, air pressure and the like are controlled by the control unit <NUM> and the like.

The printer <NUM> includes a dryer <NUM>. The printing paper P moving out from the head case <NUM> passes between the two transport rollers 82C and passes inside the dryer <NUM>. By drying the printing paper P by the dryer <NUM>, the printing paper P that is overlapped and wound is adhered to itself at the collection roller 80B, and it is difficult for the undried liquid to be rubbed.

The printer <NUM> includes a sensor unit <NUM>. The sensor unit <NUM> is configured by a position sensor, a speed sensor, a temperature sensor, or the like. The control unit <NUM> may determine a status of each portion of the printer <NUM> from information from the sensor unit <NUM> to control each portion of the printer <NUM>.

The printer <NUM> may include a cleaning unit configured to clean the liquid discharge head <NUM>. The cleaning unit performs cleaning by wiping or capping, for example. For example, by rubbing a surface of a portion from which liquid is to be discharged, for example, a discharge hole surface 4A (see <FIG>) of the liquid discharge head <NUM> by using a flexible wiper, wiping removes liquid that has been attached to the surface.

The cleaning by the capping will be done as follows, for example. First, the portion where liquid is to be discharged, for example, the discharge hole surface 4A, is covered with a cap (this is referred to as capping), and the discharge hole surface 4A and the cap create a substantially sealed space. By repeating discharge of liquid in such a state, liquid having viscosity higher than that of the standard state, foreign matters, and the like that have become clogged in the discharge hole <NUM> (see <FIG>, and the like) are removed.

Next, the liquid discharge head <NUM> according to an embodiment will be described with reference to <FIG>. <FIG> is an exploded perspective view schematically illustrating the liquid discharge head <NUM> according to an embodiment. <FIG> is an enlarged plan view of the liquid discharge head <NUM>. <FIG> illustrates a part of the liquid discharge head <NUM> in an enlarged manner, and a piezoelectric actuator substrate <NUM> is omitted in the right half of the figure. <FIG> is an enlarged view of a region surrounded by a dashed-dotted line illustrated in <FIG>. In <FIG> and <FIG>, some channels are omitted for the purpose of explanation, and in order to facilitate the understanding of the drawings, manifolds <NUM> and the like to be illustrated by using a dashed line are illustrated by using a solid line. <FIG> is a cross-sectional view along a line A-A illustrated in <FIG>.

As illustrated in <FIG>, the liquid discharge head <NUM> includes a head body 2a including a flow channel member <NUM> and a piezoelectric actuator substrate <NUM>, a reservoir <NUM>, an electrical circuit substrate <NUM>, and a head cover <NUM>. The head body 2a has a first surface configured to discharge liquid and a second surface facing the first surface. In the following, the first surface will be described as the discharge hole surface 4A in the flow channel member <NUM> and the second surface will be described as a pressurizing chamber surface 4B.

The piezoelectric actuator substrate <NUM> is positioned on the pressurizing chamber surface 4B of the flow channel member <NUM>. Two signal transmission units <NUM> are electrically connected to the piezoelectric actuator substrate <NUM>. Each signal transmission unit <NUM> includes a plurality of drive integrated circuits (ICs) <NUM>. Note that, in <FIG>, one of the signal transmission units <NUM> is omitted.

The signal transmission unit <NUM> provides a signal to each of displacement elements <NUM> (see <FIG>) of the piezoelectric actuator substrate <NUM>. The signal transmission unit <NUM> can be formed by, for example, a flexible printed circuit (FPC) or the like.

Drive ICs <NUM> are mounted on the signal transmission unit <NUM>. The drive IC <NUM> controls driving of each displacement element <NUM> (see <FIG>) of the piezoelectric actuator substrate <NUM>.

The reservoir <NUM> is positioned on the pressurizing chamber surface 4B other than the piezoelectric actuator substrate <NUM>. The reservoir <NUM> includes a channel therein, and is supplied with liquid through an opening 40a from the outside. The reservoir <NUM> has a function of supplying liquid to the flow channel member <NUM> and a function of storing the liquid.

An electrical circuit substrate <NUM> is erected on the reservoir <NUM>. A plurality of connectors <NUM> are positioned on both main surfaces of the electrical circuit substrate <NUM>. An end portion of the signal transmission unit <NUM> is housed in each connector <NUM>. Connectors <NUM> for power supply are positioned on an end surface on an opposite side to the reservoir <NUM> of the electrical circuit substrate <NUM>. The electrical circuit substrate <NUM> distributes an electrical current supplied from the outside via the connectors <NUM> to the connectors <NUM>, and supplies the electrical current to the signal transmission unit <NUM>.

A head cover <NUM> has openings 90a. The head cover <NUM> is positioned on the reservoir <NUM>, and covers the electrical circuit substrate <NUM>. With this, the electrical circuit substrate <NUM> is sealed. The connectors <NUM> of the electrical circuit substrate <NUM> are inserted so as to be exposed to the outside from the openings 90a. The drive IC <NUM> is in contact with a side surface of the head cover <NUM>. The drive IC <NUM> is pressed against the side surface of the head cover <NUM>, for example. Due to this, heat generated by the drive IC <NUM> is dissipated (radiated) from a contact portion on the side surface of the head cover <NUM>. A more specific configuration of the head cover <NUM> will be described later with reference to <FIG> and the subsequent figures.

Note that the liquid discharge head <NUM> may further include other members other than these members.

As illustrated in <FIG>, <FIG>, and <FIG>, the head body 2a includes the flow channel member <NUM> and the piezoelectric actuator substrate <NUM>.

The flow channel member <NUM> has a flat plate shape and includes a channel therein. The flow channel member <NUM> includes the manifolds <NUM>, a plurality of discharge holes <NUM>, and a plurality of pressurizing chambers <NUM>. The plurality of pressurizing chambers <NUM> are connected to the manifolds <NUM>. Each of the plurality of discharge holes <NUM> is connected to the corresponding one of the plurality of pressurizing chambers <NUM>. The pressurizing chamber <NUM> is open in the upper surface of the flow channel member <NUM>, and the upper surface of the flow channel member <NUM> is the pressurizing chamber surface 4B. Furthermore, openings 5a connected to the manifolds <NUM> are provided on the pressurizing chamber surface 4B of the flow channel member <NUM>. Liquid is supplied through the openings 5a from the reservoir <NUM> (see <FIG>) to the interior of the flow channel member <NUM>.

In the example illustrated in <FIG>, the head body 2a is provided with four manifolds <NUM> inside the flow channel member <NUM>. The manifold <NUM> has a long thin shape extending along the longitudinal direction of the flow channel member <NUM>, and at both ends thereof, the opening 5a of the manifold <NUM> is formed in the upper surface of the flow channel member <NUM>. In the present embodiment, the four manifolds <NUM> are independently provided.

The flow channel member <NUM> is formed such that the plurality of pressurizing chambers <NUM> expand in two dimensions. The pressurizing chamber <NUM> is a hollow region having a substantially diamond-shaped planar shape with corner portions that are rounded. The pressurizing chambers <NUM> are open in the pressurizing chamber surface 4B that is the upper surface of the flow channel member <NUM>, and are blocked by the piezoelectric actuator substrate <NUM> being connected.

The pressurizing chambers <NUM> constitute rows of pressurizing chambers that are arranged in the longitudinal direction. The pressurizing chambers <NUM> constituting each row of pressurizing chambers are arranged in a staggered manner so that the corner portions of the pressurizing chambers are positioned between two rows of pressurizing chambers in adjacent rows of pressurizing chambers. A pressurizing chamber group is configured by four rows of pressurizing chambers connected to one manifold <NUM>, and the flow channel member <NUM> has four pressurizing chamber groups. The relative arrangement of the pressurizing chambers <NUM> within each pressurizing chamber group is the same, and each of the pressurizing chamber groups is arranged so as to be slightly shifted to each other in the longitudinal direction.

The pressurizing chamber <NUM> and the manifold <NUM> are connected through a separate supply channel <NUM>. The separate supply channel <NUM> includes a squeeze <NUM> having a width narrower than those of the other portions. The squeeze <NUM> has a higher channel resistance due to the width narrower than those of the other portions of the separate supply channel <NUM>. In this way, when the channel resistance of the squeeze <NUM> is high, the pressure generated in the pressurizing chamber <NUM> is less likely to be released to the manifold <NUM>.

The discharge hole <NUM> is disposed at a position that avoids a region of the flow channel member <NUM> facing the manifold <NUM>. In other words, the discharge hole <NUM> does not overlap with the manifold <NUM> when the flow channel member <NUM> is viewed as being transmitted from the pressurizing chamber surface 4B. Furthermore, in a plan view, the discharge holes <NUM> are disposed so as to fit within a mounting region of the piezoelectric actuator substrate <NUM>. These discharge holes <NUM> occupy a region having approximately the same size and shape as those of the piezoelectric actuator substrate <NUM> as one group, and droplets are discharged from the discharge holes <NUM> by displacing the corresponding displacement elements <NUM> of the piezoelectric actuator substrate <NUM>.

As illustrated in <FIG>, the flow channel member <NUM> has a laminated structure in which a plurality of plates are laminated. These plates are a cavity plate 4a, a base plate 4b, an aperture (squeeze) plate 4c, a supply plate 4d, manifold plates 4e to <NUM>, a cover plate <NUM>, and a nozzle plate 4i in order from the upper surface of the flow channel member <NUM>.

Many holes are formed in these plates. Due to a thickness of each plate being approximately <NUM> to <NUM>, the forming accuracy of the holes to be formed can be increased. The respective plates are laminated in alignment such that these holes communicate with each other to form the separate channels <NUM> and the manifolds <NUM>. The head body 2a has a configuration in which the pressurizing chambers <NUM> are disposed on the upper surface of the flow channel member <NUM>, the manifolds <NUM> are provided at a lower surface side of the interior of the flow channel member <NUM>, the discharge holes <NUM> are disposed on a lower surface of the flow channel member <NUM>, respective portions constituting the separate channels <NUM> are disposed close to each other at different positions, and the manifolds <NUM> and the discharge holes <NUM> are connected through the pressurizing chambers <NUM>.

As illustrated in <FIG> and <FIG>, the piezoelectric actuator substrate <NUM> includes piezoelectric ceramic layers 21a and 21b, a common electrode <NUM>, separate electrodes <NUM>, connecting electrodes <NUM>, dummy connecting electrodes <NUM>, and surface electrodes <NUM>. The piezoelectric actuator substrate <NUM> is laminated with the piezoelectric ceramic layers 21a, the common electrode <NUM>, the piezoelectric ceramic layers 21b, and the separate electrodes <NUM> in this order.

Each of the piezoelectric ceramic layers 21a and 21b has a thickness of approximately <NUM>. Any layer of the piezoelectric ceramic layers 21a and 21b extends across the plurality of pressurizing chambers <NUM>. A lead zirconate titanate (PZT)-based ceramic material having ferroelectricity may be used for these piezoelectric ceramic layers 21a and 21b.

The common electrode <NUM> is formed over substantially the entire surface in a surface direction in a region between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode <NUM> overlaps with all of the pressurizing chambers <NUM> in a region facing the piezoelectric actuator substrate <NUM>. A thickness of the common electrode <NUM> is approximately <NUM>. For example, a metal material such as an Ag-Pd-based material may be used for the common electrode <NUM>.

The separate electrode <NUM> includes a separate electrode body 25a and an extraction electrode 25b. The separate electrode body 25a is positioned in a region facing the pressurizing chamber <NUM> on the piezoelectric ceramic layer 21b. The separate electrode body 25a is slightly smaller than the pressurizing chamber <NUM>, and has a shape substantially similar to that of the pressurizing chamber <NUM>. The extraction electrode 25b is extracted from the separate electrode body 25a. The connecting electrode <NUM> is formed in a portion extracted out of the region facing the pressurizing chamber <NUM> at one end of the extraction electrode 25b. For example, a metal material such as an Au-based material may be used for the separate electrode <NUM>.

The connecting electrode <NUM> is positioned on the extraction electrode 25b, has a thickness of approximately <NUM>, and is formed in a protruding shape. In addition, the connecting electrode <NUM> is electrically connected to an electrode provided in the signal transmission unit <NUM> (see <FIG>). For example, silver-palladium containing glass frit may be used for the connecting electrode <NUM>.

The dummy connecting electrode <NUM> is positioned on the piezoelectric ceramic layer 21b and is positioned so as not to overlap with various electrodes such as the separate electrodes <NUM>. The dummy connecting electrode <NUM> connects the piezoelectric actuator substrate <NUM> and the signal transmission unit <NUM>, and increases connection strength. Also, the dummy connecting electrode <NUM> equalizes the distribution of the contact positions of the piezoelectric actuator substrate <NUM> and the piezoelectric actuator substrate <NUM>, and stabilizes electrical connection. The dummy connecting electrode <NUM> may be formed of an equivalent material and by an equivalent process as the connecting electrode <NUM>.

The surface electrode <NUM> is formed at a position where the separate electrodes <NUM> are avoided on the piezoelectric ceramic layer 21b. The surface electrode <NUM> is connected to the common electrode <NUM> through a via hole formed in the piezoelectric ceramic layer 21b. As a result, the surface electrode <NUM> is grounded and held at a ground potential. The surface electrode <NUM> may be formed of an equivalent material and by an equivalent process as the separate electrode <NUM>.

The plurality of separate electrodes <NUM> are individually electrically connected to the control unit <NUM> (see <FIG>) via the signal transmission unit <NUM> and wirings in order to individually control the electrical potentials. Regarding the piezoelectric ceramic layer 21b sandwiched between the separate electrode <NUM> and the common electrode <NUM>, when the separate electrode <NUM> and the common electrode <NUM> are set to different potentials and an electric field is applied to the piezoelectric ceramic layer 21b in a polarization direction thereof, the portion where the electric field is applied serves as an active section that is distorted due to the piezoelectric effect. As a result, the separate electrode <NUM>, the piezoelectric ceramic layer 21b, and the common electrode <NUM> that face the pressurizing chamber <NUM> function as the displacement element <NUM>. Then, due to unimorph deformation of the displacement element <NUM>, the pressurizing chamber <NUM> is pressed and liquid is discharged from the discharge hole <NUM>.

Here, a driving procedure in the present embodiment will be described. The separate electrodes <NUM> are set in advance to a higher potential (hereinafter referred to as a high potential) than that of the common electrode <NUM>. Each time there is a demand for discharge, the separate electrodes <NUM> are set to the same potential as that of the common electrode <NUM> (hereinafter referred to as a low potential) once, and then are set to the high potential again at a predetermined timing. As a result, when the separate electrodes <NUM> are set to the low potential, the piezoelectric ceramic layers 21a and 21b return to their original shape, and a volume of the pressurizing chamber <NUM> is increased compared with an initial state (a state in which the potentials of the two electrodes are different).

At this time, negative pressure is applied to the pressurizing chamber <NUM>, and liquid is sucked from the manifold <NUM> side into the interior of the pressurizing chamber <NUM>. Then, when the separate electrodes <NUM> are set to the high potential again, the piezoelectric ceramic layers 21a and 21b are deformed so as to have a protruding shape toward the pressurizing chamber <NUM> side, and pressure inside the pressurizing chamber <NUM> becomes positive pressure due to a decrease in the volume of the pressurizing chamber <NUM>. As a result, the pressure on the liquid inside the pressurizing chamber <NUM> rises, and droplets are discharged. That is, in order to discharge the droplets, a driving signal including a pulse with the high potential being as a reference will be supplied to the separate electrodes <NUM>. The pulse width may be set to an acoustic length (AL) that is a length of time when a pressure wave propagates from the squeeze <NUM> to the discharge hole <NUM>. Due to this, when the interior of the pressurizing chamber <NUM> is inverted from the negative pressure state to the positive pressure state, pressure in both states is combined, and droplets can be discharged at a higher pressure.

Additionally, in gradation printing, gradation expression is performed by the number of droplets to be continuously discharged from the discharge hole <NUM>, that is, an amount (volume) of droplets to be adjusted by the number of droplets to be discharged. Thus, the number of droplets to be discharged corresponding to the specified gradation expression is continuously performed from the discharge hole <NUM> corresponding to the specified dot region. In general, when the liquid discharge is continuously performed, an interval between the pulses that are supplied to discharge the droplets may be set to the AL. Due to this, a period of a residual pressure wave of pressure generated in discharging the droplets discharged earlier matches a period of a pressure wave of pressure to be generated in discharging droplets to be discharged later. As a result, the pressure for discharging the droplets can be amplified by superimposing the residual pressure wave and the pressure wave. Note that in this case, the speed of the droplets to be discharged later is increased, and impact points of the plurality of droplets become close.

Next, the head cover <NUM> will be described with reference to <FIG>. <FIG> is a schematic cross-sectional view of the liquid discharge head <NUM> according to an embodiment. Note that an X direction illustrated in <FIG> is a direction from a top plate <NUM> toward a second surface <NUM> of the head body 2a. <FIG> is a perspective view of the head cover <NUM>. <FIG> is a plan view of the head cover <NUM>. <FIG> is a side view of the head cover <NUM>. <FIG> is a cross-sectional view taken along a line B-B illustrated in <FIG>. <FIG> is an enlarged view of a portion D1 illustrated in <FIG> is an enlarged view of a portion D2 illustrated in <FIG>. <FIG> is a cross-sectional view taken along a line C-C illustrated in <FIG>. <FIG> is an enlarged view of a portion D3 illustrated in <FIG>.

As described above, the liquid discharge head <NUM> includes the flow channel member <NUM>, the piezoelectric actuator substrate <NUM>, the reservoir <NUM>, the electrical circuit substrate <NUM>, and the head cover <NUM>. The flow channel member <NUM> and the piezoelectric actuator substrate <NUM> constitute the head body 2a. The flow channel member <NUM> includes the discharge hole surface 4A and the pressurizing chamber surface 4B. In addition, the flow channel member <NUM> includes a side cover <NUM> on the pressurizing chamber surface 4B. The side cover <NUM> protrudes from the pressurizing chamber surface 4B toward the top plate <NUM> side in a state where the head cover <NUM> is mounted.

The piezoelectric actuator substrate <NUM> is electrically connected to the signal transmission unit <NUM>. The signal transmission unit <NUM> includes the plurality of drive ICs <NUM> that drive the head body 2a. The signal transmission unit <NUM> is drawn upward from the piezoelectric actuator substrate <NUM> through the side of the reservoir <NUM>. Note that the plurality of drive ICs <NUM> may be included. The plurality of drive ICs <NUM> are arranged side by side, for example, in a direction orthogonal to the X direction (in the longitudinal direction of the liquid discharge head <NUM>).

As described above, the electrical circuit substrate <NUM> is provided with a connector <NUM> for power supply. The connector <NUM> protrudes in a direction opposite to the X direction from the electrical circuit substrate <NUM>. Note that a plurality of connectors <NUM> may be provided. In this case, a plurality of openings 90a of the head cover <NUM> in the top plate <NUM> are provided according to the plurality of connectors <NUM>.

As illustrated in <FIG>, the head body 2a includes a first surface <NUM> that discharges liquid and a second surface <NUM> that faces the first surface <NUM>. Note that the first surface <NUM> of the head body 2a is the discharge hole surface 4A in the flow channel member <NUM>, and the second surface <NUM> is the pressurizing chamber surface 4B in the flow channel member <NUM>.

As illustrated in <FIG>, the head cover <NUM> has a bottomed cylindrical shape. In other words, the head cover <NUM> has a box shape having openings. The head cover <NUM> can be made of metal such as aluminum, or resin or the like, for example. As illustrated in <FIG>, the head cover <NUM> is positioned on the head body 2a so as to cover at least the second surface <NUM> of the head body 2a while housing the signal transmission unit <NUM> including the drive ICs <NUM>, the reservoir <NUM>, and the electrical circuit substrate <NUM>. The head cover <NUM> extends in the X direction.

The head cover <NUM> includes the top plate <NUM>, a first side plate <NUM>, and a second side plate <NUM>. The top plate <NUM> has a rectangular shape having long sides and short sides, and faces the second surface <NUM> of the head body 2a. The top plate <NUM> is long in the longitudinal direction of the liquid discharge head <NUM>. The first side plate <NUM> has a rectangular shape, and is connected to the long side of the top plate <NUM>. A pair of the first side plates <NUM> are provided, for example, and face each other with the top plate <NUM> sandwiched. The first side plate <NUM> is long in the longitudinal direction of the liquid discharge head <NUM>.

As illustrated in <FIG>, the first side plate <NUM> includes a first portion <NUM> and a second portion <NUM>. The first portion <NUM> is a portion that extends in the X direction. The second portion <NUM> is a portion positioned closer to the second surface <NUM> than the first portion <NUM>. Of an inner surface 92a of the first side plate <NUM>, an inner surface of the first portion <NUM> (that is, an inner surface 92a of the first side plate <NUM>) is in contact with the drive IC <NUM> in a state where the head cover <NUM> is mounted. Of the inner surface 92a of the first side plate <NUM>, an inner surface of the second portion <NUM> (that is, the inner surface 92a of the first side plate <NUM>) includes a diameter expanding portion <NUM>, which will be described below, having a diameter expanding toward the second surface <NUM>.

The second side plate <NUM> has a rectangular shape, is connected to the short sides of the top plate <NUM>, and is connected to the first side plate <NUM>. Furthermore, a pair of the second side plates <NUM> are provided, for example, and face each other with the top plate <NUM> sandwiched. Note that the drive IC <NUM> is not in contact with an inner surface 93a of the second side plate <NUM> in a state where the head cover <NUM> is mounted. In addition, respective areas of the top plate <NUM>, the first side plate <NUM>, and the second side plate <NUM> are larger in the order of the first side plate <NUM>, the top plate <NUM>, and the second side plate <NUM>.

As illustrated in <FIG>, a thickness d2 of the first side plate <NUM> is thinner than a thickness d1 of the top plate <NUM>. Also, although not illustrated, the thickness d2 of the first side plate <NUM> is thicker than a thickness d3 of the second side plate <NUM>. Also, although not illustrated, the thickness d3 of the second side plate <NUM> is thinner than the thickness d1 of the top plate <NUM>. In other words, regarding the magnitude relationship among the thickness d1 of the top plate <NUM>, the thickness d2 of the first side plate <NUM>, and the thickness d3 of the second side plate <NUM>, d1 > d2 > d3 is satisfied, the first side plate <NUM> having the largest area is the thickest, the top plate <NUM> is the second thickest, and the second side plate <NUM> having the smallest area is the thinnest.

Here, each of the thicknesses d1, d2, and d3 of the top plate <NUM>, the first side plate <NUM>, and the second side plate <NUM> is an average value of each of the plates <NUM>, <NUM>, and <NUM>. In other words, for each of the top plate <NUM>, the first side plate <NUM>, and the second side plate <NUM>, for example, thicknesses at three points are measured, and the average value thereof is defined as each thickness. As the thicknesses d1, d2, and d3 of the respective plates <NUM>, <NUM>, and <NUM>, when the liquid discharge head <NUM> is an inkjet head, for example, the thickness d1 of the top plate <NUM> is approximately <NUM>, the thickness d2 of the first side plate <NUM> is approximately <NUM>, and the thickness d3 of the second side plate <NUM> is approximately <NUM>. The head cover <NUM> is manufactured by pressing a single plate.

As illustrated in <FIG>, the head cover <NUM> has a first side S1, a second side S2, and a third side S3. The first side S1 is a portion connecting the first side plate <NUM> and the second side plate <NUM>. The first side S1 extends in the X direction illustrated in <FIG>. The second side S2 is a portion connecting the top plate <NUM> and the first side plate <NUM>. The second side S2 extends in the longitudinal direction of the head cover <NUM>. The third side S3 is a portion connecting the top plate <NUM> and the second side plate <NUM>. The third side S3 extends in a direction orthogonal to the longitudinal direction of the head cover <NUM> (in a lateral direction of the head cover <NUM>). A length of the second side S2 is longer than a length of the first side S <NUM>, and is longer than a length of the third side S3. Also, the length of the first side S <NUM> is longer than the length of the third side S3.

As illustrated in <FIG>, <FIG>, the first side S1 has a first radius R1 such that the outer surface is a curved surface. Note that the third side S3 may also have the first radius R1. Additionally, as illustrated in <FIG>, the second side S2 has a second radius R2 such that the outer surface is a curved surface. Here, regarding curvatures of the two radii R1 and R2, that of the first radius R1 is larger than that of the second radius R2. Note that the curvatures of the radii R1 and R2 are measured by using a known laser curvature measuring device.

As illustrated in <FIG>, the diameter expanding portion <NUM> is positioned at an end portion, of the inner surface 92a of the second portion <NUM> of the first side plate <NUM>, on the pressurizing chamber surface 4B side. When viewed from the top surface of the head cover <NUM>, in other words, when viewed from the top plate <NUM> side, the diameter expanding portion <NUM> is a portion where a diameter of the inner surface 92a is widened. In other words, the head cover <NUM> has a shape in which an opening expands when viewed from the top plate <NUM> side.

The diameter expanding portion <NUM> has a pointed tip and a tip edge portion. The inner surface 92a of the tip edge portion has a radius (third radius) R3. This third radius R3 forms the diameter expanding portion <NUM> of the second portion <NUM>. In other words, the third radius R3 that curves outward is provided on the inner surface 92a of the tip edge portion, and thus, the diameter expanding portion <NUM> is formed in which the diameter of the head cover <NUM> expands. In other words, the cross-section shape of the diameter expanding portion <NUM> is a rounded shape.

With the first side plate <NUM> having the third radius R3 on the inner surface 92a of the second portion <NUM>, a tip opening of the head cover <NUM> expands outward. Note that the third radius R3 may also be provided at the tip edge portion serving as the second surface <NUM> side in the inner surface 93a of the second side plate <NUM>.

The diameter expanding portion <NUM> includes a protruding portion <NUM> that protrudes outward (see <FIG>), on the outer surface. That is, the diameter expanding portion <NUM> may include the protruding portion <NUM>, which protrudes outward, on the outer surface. Furthermore, the protruding portion <NUM> extends in the X direction (see <FIG>). The protruding portion <NUM> is a portion, which is illustrated in <FIG>, positioned on the right side of the page relative to an imaginary line extending from the first portion 921a in the X direction. In the protruding portion <NUM>, a length in the X direction is longer than a length (thickness) in the thickness direction of the first side plate <NUM>. Furthermore, the protruding portion <NUM> extends in the X direction. According to such a configuration, when the atomized liquid (for example, ink mist) travels through the protruding portion <NUM>, the liquid can be guided along one direction to a tip edge of the first side plate <NUM>. As a result, the intrusion of liquid into the interior of the head cover <NUM> can be suppressed.

Next, an attachment operation of the head cover <NUM> will be described with reference to <FIG> are explanatory diagrams of the attachment operation of the head cover <NUM>, <FIG> illustrates a state before the attachment of the head cover <NUM>, and <FIG> illustrates a state after the attachment of the head cover <NUM>.

As illustrated in <FIG>, the head cover <NUM> is mounted to the head body 2a from the X direction. At this time, since the tip edge portion of the first side plate <NUM> is not in contact with the drive IC <NUM> housed in the head cover <NUM> by the diameter expanding portion <NUM>, the drive IC <NUM> is less likely to be damaged. Alternatively, since the head cover <NUM> includes the diameter expanding portion <NUM>, even when the diameter expanding portion <NUM> and the drive IC <NUM> are in contact with each other, the diameter expanding portion <NUM> can smoothly guide the drive IC <NUM> to the interior of the head cover <NUM>, and the drive IC <NUM> is less likely to be damaged.

As illustrated in <FIG>, in a state where the head cover <NUM> is mounted, the connectors <NUM> are inserted through the plurality of openings 90a of the top plate <NUM>, thereby are positioned, and as a result, the head cover <NUM> is fixed to the head body 2a.

According to such a configuration, since the head cover <NUM> is fixed by inserting the connectors <NUM> through the openings 90a of the top plate <NUM> having a thick thickness, it is possible to firmly fix the head cover <NUM> and the electrical circuit substrate <NUM>. That is, the head cover <NUM> can be firmly fixed to the head body 2a.

Next, the tip edge portion (diameter expanding portion <NUM>) in an attached state of the head cover <NUM> will be described with reference to <FIG> are enlarged views of a portion E illustrated in <FIG>, and <FIG> illustrates a state before a sealing member <NUM> is disposed, and <FIG> illustrates a state after the sealing member <NUM> is disposed.

As illustrated in <FIG>, the head cover <NUM> is disposed separated from the flow channel member <NUM> in a state of being mounted to the head body 2a. That is, the head cover <NUM> has a gap with the flow channel member <NUM>, and is not in contact with the flow channel member <NUM>. Since the tip edge portion of at least the first side plate <NUM>, of the tip edge portion of the first side plate <NUM> serving as the tip edge portion of the head cover <NUM>, is not in contact with the flow channel member <NUM>, heat is less likely to be transferred from the first side plate <NUM> to the flow channel member <NUM>. As a result, transfer of heat generated by the drive IC <NUM> to the flow channel member <NUM> can be suppressed. As a result, the temperature of the liquid flowing through the flow channel member <NUM> is less likely to increase, and the discharge characteristics are less likely to decrease.

Further, the head cover <NUM> may cover the side cover <NUM> in the state of being mounted to the head body 2a. According to such a configuration, it is difficult for atomized liquid (for example, ink mist) to intrude from a gap between the head cover <NUM> and the side cover <NUM>. As a result, it is possible to suppress the intrusion of liquid into the interior of the liquid discharge head <NUM>. This can improve sealing properties of the liquid discharge head <NUM>.

As illustrated in <FIG>, the sealing member <NUM> is, for example, sealing resin, and is positioned between the head cover <NUM> and the side cover <NUM> so as to seal the gap between the head cover <NUM> and the flow channel member <NUM>. With such a configuration, by configuring a dual sealing structure of the side cover <NUM> and the sealing member <NUM>, the sealing properties can be further improved. In addition, since the diameter expanding portion <NUM> has the third radius R3, and thus, a surface area thereof increases, a contact area with the sealing member <NUM> increases, which can improve the sealing properties of the liquid discharge head <NUM>. The sealing member <NUM> is formed of epoxy-based, silicon-based, or urethane-based thermosetting resin.

According to the above-described embodiment, since the thickness d2 of the first side plate <NUM> is thinner than the thickness d1 of the top plate <NUM>, the heat generated by the drive IC <NUM> can be released more by the thin first side plate <NUM>, and the strength of the head cover <NUM> can be maintained by the thick top plate <NUM>. In other words, by reducing the thickness of the first side plate <NUM> being in contact with the drive IC <NUM>, it is possible to maintain the strength of the head cover <NUM> by increasing the thickness of the top plate <NUM>, where external force easily occurs, while improving the heat radiating properties of heat generated by the drive IC <NUM>. As a result, it is possible to suppress a decrease in strength of the head cover <NUM> while improving the heat radiating properties.

Additionally, the thickness d3 of the second side plate <NUM> may be thinner than the thickness d2 of the first side plate <NUM>. According to such a configuration, more heat can be released from the first side plate <NUM> to the thin second side plate <NUM>.

Additionally, the area of the first side plate <NUM> may be larger than the area of the second side plate <NUM>. Also in such a configuration, since heat transmitted to the first side plate <NUM> can be radiated to the second side plate <NUM>, and the second side plate <NUM> is less likely to be in contact with other members, even when the second side plate <NUM> is thin, the second side plate <NUM> is less likely to be damaged. That is, it is possible to suppress a decrease in strength of the head cover <NUM> while improving the heat radiating properties of the liquid discharge head <NUM>.

Additionally, the thickness d2 of the first side plate <NUM> may be larger than the thickness d3 of the second side plate <NUM>. With such a configuration, since the strength of the first side plate <NUM> in contact with the drive IC <NUM> can be ensured and the first side plate <NUM> is less likely to be damaged, it is possible to suppress a decrease in sealing properties of the liquid discharge head <NUM>.

Additionally, the first side S1 may have the first radius R1. With such a configuration, stress generated in the first side S1 of the head cover <NUM> due to the elongation of the first side plate <NUM> can be relaxed. As a result, the strength of the head cover <NUM> is increased, the head cover <NUM> is less likely to be broken, and it is possible to suppress the decrease in sealing properties of the liquid discharge head <NUM>.

Furthermore, the second side S2 may have the second radius R2. With such a configuration, stress generated in the second side S2 of the head cover <NUM> due to the elongation of the first side plate <NUM> can be relaxed. As a result, the strength of the head cover <NUM> is increased, the head cover <NUM> is less likely to be broken, and it is possible to suppress the decrease in sealing properties of the liquid discharge head <NUM>.

Additionally, the size of the first radius R1 may be larger than the size of the second radius R2. With such a configuration, stress generated in the first side S1 to which larger stress is applied among stress generated in each of the sides S1, S2, and S3 of the head cover <NUM> due to the elongation of the first side plate <NUM> can be more relaxed. That is, even when the first side plate <NUM> largely extends in the longitudinal direction thereof, the stress can be relaxed by the large first radius R1. As a result, the strength of the head cover <NUM> is increased, the head cover <NUM> is less likely to be broken, and it is possible to suppress the decrease in sealing properties of the liquid discharge head <NUM>.

In addition, the inner surface 92a of the tip edge portion of at least the first side plate <NUM> among the tip edge portions of the side plates that serve as the tip edge portion of the head cover <NUM> may have a rounded shape. With such a configuration, the contact area of the sealing member (sealing resin) <NUM> is increased, the sealing member <NUM>, such as sealing resin, is easily applied, and the applied sealing member <NUM> is firmly held. As a result, the sealing properties of the liquid discharge head <NUM> and the sealing workability of applying the sealing member <NUM> can be improved.

Then, with the printer <NUM> according to the above-described embodiment, in the liquid discharge head <NUM>, it is possible to suppress a decrease in strength of the head cover <NUM> while improving the heat radiating properties.

Next, a modified example of the head cover will be described with reference to <FIG> are explanatory diagrams of modified examples (head covers 90A, 90B, and 90C) of the head cover <NUM> described above, respectively. As illustrated in <FIG>, in the head cover 90A according to the modified example, a surface roughness of the outer surface 92b in the first side plate <NUM> is rougher than a surface roughness of the inner surface 92a. For example, the roughness of the outer surface 92b is in a range from <NUM> to <NUM>. Additionally, the roughness of the inner surface 92a is in a range from <NUM> to <NUM>. Additionally, the surface roughness of the inner surface 92a in the first side plate <NUM> is rougher than the surface roughness of the top plate <NUM>.

According to such a configuration, since the surface roughness of the outer surface 92b in the first side plate <NUM> is rougher than the surface roughness of the inner surface 92a that is in contact with the drive IC <NUM>, contact properties between the inner surface 92a and the drive IC <NUM> can be ensured, and at the same time, since the surface area of the outer surface increases, heat radiating properties by the first side plate <NUM> can be improved.

Note that the surface roughness refers to a surface roughness measured in accordance with "JIS B <NUM> (<NUM>)", for example. A contact type surface roughness gauge or a non-contact type surface roughness gauge may be used for the measurement. As measurement conditions, for example, a measurement length is set to <NUM>, a cutoff value is set to <NUM>, a spot diameter is <NUM>, and a scanning speed is set to <NUM>/sec. Note that the measurement conditions may be set as appropriate.

As illustrated in <FIG>, the head cover 90B according to the modified example includes a groove (recessed portion) <NUM> so as to be positioned between the plurality of drive ICs <NUM> in at least any one of the surfaces 92a and 92b of the inner surface 92a and the outer surface 92b in the first side plate <NUM>. The groove <NUM> is along the X direction. Note that a plurality of grooves <NUM> may be provided.

According to such a configuration, when the plurality of drive ICs <NUM> are provided, heat is not easily transferred between the adjacent drive ICs <NUM>. This makes the drive IC <NUM> less likely to malfunction.

<FIG> is a drawing corresponding to <FIG> of an embodiment. As illustrated in <FIG>, the head cover 90C according to the modified example is disposed so as to be in contact with the side cover <NUM>. For example, in the example of <FIG>, the diameter expanding portion <NUM> of the head cover 90C is in contact with a tip portion 43a of the side cover <NUM>.

Additionally, in the example illustrated in <FIG>, the side cover <NUM> is configured of an electrically conductive material (for example, metal). Furthermore, a base end portion 43b of the side cover <NUM> fits a recessed portion 4B <NUM> formed in the pressurizing chamber surface 4B of the flow channel member <NUM>.

With such a configuration, it is possible to electrically connect between the flow channel member <NUM> and the head cover 90C via the side cover <NUM>. As a result, when the flow channel member <NUM> is charged by static electricity generated during printing, such static electricity can be smoothly released to a GND terminal of the electrical circuit substrate <NUM> (see <FIG>) via the side cover <NUM> and the head cover 90C.

Thus, according to the example of <FIG>, it is possible to suppress a reduction in printing quality of the recording device <NUM> due to the static electricity generated during printing.

Additionally, in the example of <FIG>, the electrical connection between the flow channel member <NUM> and the side cover <NUM> can be improved by fitting the base end portion 43b of the side cover <NUM> to the recessed portion 4B <NUM> formed in the pressurizing chamber surface 4B of the flow channel member <NUM>.

Thus, according to the example of <FIG>, it is possible to further suppress the reduction in printing quality of the recording device <NUM> due to the static electricity generated during printing.

Note that, in the example of <FIG>, although the example is illustrated in which the tip portion 43a of the side cover <NUM> is in contact with the diameter expanding portion <NUM> of the head cover 90C. a portion which the tip portion 43a of the side cover <NUM> contacts is not limited to the diameter expanding portion <NUM> of the head cover 90C.

Additionally, in the above-described embodiment, although the displacement element <NUM> using piezoelectric deformation is illustrated as a pressurizing portion, the present invention is not limited thereto, and other elements are applicable as long as liquid in the pressurizing chamber <NUM> can be pressurized, for example, an element in which the liquid in the pressurizing chamber <NUM> is heated and boiled to generate pressure, or an element in which micro electro mechanical systems (MEMS) are used may be applicable.

Further, in the above-described embodiment, the cross-section shape of the inner surface 92a of the diameter expanding portion <NUM> in the first side plate <NUM> is a rounded shape, but the cross-section shape may not be a rounded shape, and, for example, a flared, inclined surface may be formed. Even when such an inclined surface is employed, since the tip opening of the head cover <NUM> expands outward, the tip edge portion of the first side plate <NUM> is not in contact with the drive IC <NUM> housed in the head cover <NUM>. This makes it difficult for the drive IC <NUM> to be damaged.

Claim 1:
A liquid discharge head (<NUM>), comprising:
a head body (2a) having a first surface (<NUM>) configured to discharge a liquid and a second surface (<NUM>) facing the first surface (<NUM>);
a drive IC (<NUM>) configured to drive the head body (2a); and
a head cover (<NUM>) manufactured by pressing a single plate and configured to cover at least the second surface (<NUM>) while housing the drive IC (<NUM>), wherein
the head cover (<NUM>) includes
a top plate (<NUM>) facing the second surface (<NUM>) and
a first side plate (<NUM>) that is connected to the top plate (<NUM>) and that is in contact with the drive IC (<NUM>),
the first side plate (<NUM>) having a thickness that is thinner than a thickness of the top plate (<NUM>).