Patent Description:
Among liquid discharge heads, for example, some are designed to include a plurality of nozzles arranged in a two-dimensional matrix manner and to not only supply liquid from a supply main channel to a pressure chamber via a supply branch channel but also collect the liquid from the pressure chamber via a collection branch channel into a collection main channel.

Conventionally, a liquid discharge head including a bypass channel and a flow rate controller is known. The bypass channel connects a common liquid chamber and a circulation common liquid chamber without a pressure chamber (an individual liquid chamber), and the flow rate controller controls a flow rate of liquid flowing through the bypass channel (<CIT>). In <CIT>, the liquid discharge head is provided to enhance bubble dischargeability and retain an effect of reducing or eliminating a change in viscosity due to circulation.

In addition, a liquid discharge head including a common supply channel, a common collection channel, and a communication path connected from the common supply channel to the common collection channel is known. In such a liquid discharge head, liquid flows from the common supply channel to the common collection channel via a pressure chamber, and one portion of the common collection channel is disposed above the common supply channel (<CIT>). In <CIT>, the liquid discharge head is provided to enhance dischargeability of bubbles inside the common supply channel.

According to each of the related-art techniques, the configuration including the bypass channel has been proposed to enhance dischargeability of bubbles inside the head. However, bubbles are not adequately discharged although a bypass channel including a unit for adjusting a flow rate of matter to be discharged (hereinafter also referred to as liquid) is disposed between a supply-side common liquid chamber and a collection-side common liquid chamber as described in the related-art techniques. For example, bubbles may remain in an individual liquid chamber at the time of initial filling or maintenance work. Moreover, bubbles may flow from a common liquid chamber or a tank to the individual liquid chamber at the time of printing operation. In such a case, discharge of liquid becomes unstable.

The present disclosure is directed to provide a discharge head that enhances bubble dischargeability at the time of initial filling and/or maintenance work and has enhanced stability of liquid discharge at the time of printing operation.

The present disclosure can provide a discharge head that enhances bubble dischargeability at the time of initial filling and/or maintenance work, and has enhanced discharge stability of liquid at the time of printing operation.

A discharge head includes: multiple nozzles from each of which a liquid is discharged; multiple pressure chambers respectively communicating with the multiple nozzles; multiple supply branch channels each communicating with two or more of the multiple pressure chambers to supply the liquid to the two or more of the pressure chambers; multiple collection branch channels each communicating with two or more of the multiple pressure chambers to collect the liquid from the two or more of the pressure chambers; a supply main channel communicating with each of the multiple supply branch channels to supply the liquid to the multiple supply branch channels; a collection main channel communicating with each of the multiple collection branch channels to collect the liquid from the multiple collection branch channels; a first bypass channel communicating with each of the supply main channel and the collection main channel to connect the supply main channel and the collection main channel; and a first open-close unit configured to: openably close the first bypass channel; and decrease a flow rate of the liquid flowing through the first bypass channel with an increase in a first pressure difference between an upstream side and a downstream side of the first open-close unit.

A discharge head is disclosed in claim <NUM>.

Hereinafter, a discharge head and a discharge apparatus according to the present disclosure are described with reference to the drawings. The present disclosure is not limited to the embodiments described below, and various modifications and enhancements are possible without departing from the scope of the disclosure. It is therefore to be understand that the present disclosure may be practiced otherwise than as specifically described herein. However, the scope of the invention is defined by the appended claims.

The discharge head of the present disclosure includes a plurality of nozzles, a plurality of pressure chambers, a plurality of supply branch channels, a plurality of collection branch channels, a supply main channel, a collection main channel, a first bypass channel, and a first open-close unit. The plurality of nozzles discharges liquid, and the plurality of pressure chambers communicates with the plurality of respective nozzles. The plurality of supply branch channels each communicates with two or more of the pressure chambers, and the plurality of collection branch channels each communicates with two or more of the pressure chambers. The supply main channel communicates with the plurality of supply branch channels, and the collection main channel communicates with the plurality of collection branch channels. The first bypass channel communicates with each of the supply main channel and the collection main channel to connect the supply main channel and the collection main channel. The first open-close unit opens and closes the first bypass channel. The supply branch channel is a channel that supplies the liquid to the two or more of the pressure chambers, and the collection branch channel is a channel that collects the liquid from the two or more of the pressure chambers. The supply main channel is a channel that supplies the liquid to the plurality of supply branch channels. The collection main channel is a channel that collects the liquid from the plurality of collection branch channels. The liquid to flow through the first bypass channel has a flow rate that is decreased with an increase in a pressure difference between an upstream side and a downstream side of the first open-close unit.

<FIG> are cross-sectional views illustrating a discharge head <NUM> according to the present disclosure. <FIG> is a cross-sectional view along the line B-B of <FIG> is a cross-sectional view along the line C-C of <FIG> is a plan view illustrating a channel arrangement of the discharge head <NUM>, and <FIG> is a cross-sectional view along the line A-A of <FIG>.

The discharge head <NUM> includes a nozzle plate <NUM>, an actuator member <NUM>, and a common channel member <NUM> that also serves as a frame member. The actuator member <NUM> includes an individual channel member (channel plate) <NUM>, a diaphragm member <NUM>, a piezoelectric element <NUM>, and a common channel member <NUM>.

The nozzle plate <NUM> includes a plurality of nozzles <NUM> that discharge liquid that is material (medium) to be discharged. The plurality of nozzles <NUM> is arranged in a two-dimensional matrix manner.

The individual channel member <NUM> provides a plurality of pressure chambers (individual liquid chambers) <NUM>, a plurality of individual supply channels <NUM>, and a plurality of individual collection channels <NUM>. The plurality of pressure chambers <NUM> communicates with the plurality of respective nozzles <NUM>, and the plurality of individual supply channels <NUM> communicates with the plurality of respective pressure chambers <NUM>. The plurality of individual collection channels <NUM> communicates with the plurality of respective pressure chambers <NUM>. The individual supply channel <NUM> includes a supply-side fluid-resistant portion <NUM>, whereas the individual collection channel <NUM> includes a collection-side fluid-resistant portion <NUM>.

The diaphragm member <NUM> forms a diaphragm <NUM> that is a deformable wall of the pressure chamber <NUM>, and the piezoelectric element <NUM> is integrally provided with the diaphragm <NUM>. In the diaphragm member <NUM>, a supply-side opening <NUM> that communicates with the individual supply channel <NUM>, and a collection-side opening <NUM> that communicates with the individual collection channel <NUM> are formed. The piezoelectric element <NUM> is a pressure generator that deforms the diaphragm <NUM> to compress liquid inside the pressure chamber <NUM>.

The common channel member <NUM> serves as a common branch channel member, and provides a plurality of supply branch channels <NUM> as common supply branch channels communicating with two or more individual supply channels <NUM>, and a plurality of collection branch channels <NUM> as common collection branch channels communicating with two or more individual collection channels <NUM>. The supply branch channels <NUM> and the collection branch channels <NUM> are alternately provided in an adjacent manner. The supply branch channel <NUM> is a channel through which liquid as matter to be discharged is supplied to two or more pressure chambers <NUM>, whereas the collection branch channel <NUM> is a channel through which liquid as matter to be discharged is collected from two or more pressure chambers <NUM>.

In the common channel member <NUM>, a supply port <NUM> and a collection port <NUM> are formed. The supply port <NUM> communicates with each of the supply-side opening <NUM> of the individual supply channel <NUM> and the supply branch channel <NUM> to connect the supply-side opening <NUM> and the supply branch channel <NUM>. The collection port <NUM> communicates with each of the collection-side opening <NUM> of the individual collection channel <NUM> and the collection branch channel <NUM> to connect the collection-side opening <NUM> and the collection branch channel <NUM>.

In addition, the common channel member <NUM> provides one portion 156a of one or a plurality of common supply main channels <NUM> communicating with the plurality of supply branch channels <NUM>, and one portion 157a of one or a plurality of common collection main channels <NUM> communicating with the plurality of collection branch channel <NUM>. The one portion 156a and the one portion 157a are provided by the common channel member <NUM> and the common channel member <NUM>.

The common channel member <NUM> serves as a common main channel member, and provides one portion 156b of the supply main channel <NUM> communicating with the plurality of supply branch channels <NUM> and one portion 157b of the collection main channel <NUM> communicating with the plurality of collection branch channels <NUM>. The one portion 156b and the one portion 157b are provided by the common channel member <NUM> and the common channel member <NUM>. The one portion 156b of the supply main channel <NUM> communicates with a supply port <NUM>, and the one portion 157b of the collection main channel <NUM> communicates with a supply port <NUM>.

The supply main channel <NUM> is a channel through which liquid as matter to be discharged is supplied to the plurality of supply branch channels <NUM>, and the collection main channel <NUM> is a channel through which liquid as matter to be discharged is collected from the plurality of collection branch channels <NUM>.

A supply-side tank <NUM> and a collection-side tank <NUM> are arranged outside the common channel member <NUM>. The supply-side tank <NUM> is a tank from which liquid is supplied to the supply main channel <NUM> via the supply port <NUM>, and the collection-side tank <NUM> is a tank to which liquid is discharged from the collection main channel <NUM> via the supply port <NUM>. The supply-side tank <NUM> includes a supply port <NUM> to which liquid is externally supplied. The collection-side tank <NUM> includes a collection port <NUM> from which liquid is externally discharged.

In the present disclosure, a first bypass channel <NUM> is arranged. The first bypass channel <NUM> communicates with each of the supply main channel <NUM> and the collection main channel <NUM> to connect the supply main channel <NUM> and the collection main channel <NUM>. Herein, the first bypass channel <NUM> is preferably a channel that connects a downstream end portion of the supply main channel <NUM> and an upstream end portion of the collection main channel <NUM>. In <FIG>, although the supply port <NUM> and the collection port <NUM> are omitted for the sake of simplicity, the supply port <NUM> is arranged on the left side (i.e., the upstream side) of the supply main channel <NUM>, and the collection port <NUM> is arranged on the left side (i.e., the downstream side) of the collection main channel <NUM>.

Bubbles tend to be accumulated in a downstream end portion (the extreme downstream side) of the supply main channel <NUM> and an upstream end portion (the extreme upstream side) of the collection main channel <NUM> since pressure is weaker and a flow rate is lower in each of the downstream end portion of the supply main channel <NUM> and the upstream end portion of the collection main channel <NUM>. Thus, the connection of the downstream end portion of the supply main channel <NUM> and the upstream end portion of the collection main channel <NUM> by the first bypass channel <NUM> can enhance bubble dischargeability.

In addition, a second bypass channel <NUM> is arranged. The second bypass channel <NUM> communicates with each of the supply branch channel <NUM> and the collection main channel <NUM> to connect the supply branch channel <NUM> and the collection main channel <NUM>. The second bypass channel <NUM> connects an end portion (the extreme downstream side) of the supply branch channel <NUM> and the collection main channel <NUM>. Accordingly, bubbles are prevented from remaining in the end portion of the supply branch channel <NUM> at the time of filling.

A third bypass channel <NUM> is also arranged. The third bypass channel <NUM> communicates with each of the collection branch channel <NUM> and the supply main channel <NUM> to connect the collection branch channel <NUM> and the supply main channel <NUM>. The third bypass channel <NUM> connects an end portion (the extreme upstream side) of the collection branch channel <NUM> and the supply main channel <NUM>. Thus, bubbles are prevented from remaining in the end portion of the collection branch channel <NUM> at the time of filling.

The first bypass channel <NUM> has a first open-close unit <NUM> that opens and closes the first bypass channel <NUM>. The second bypass channel <NUM> has a second open-close unit <NUM> that opens and closes the second bypass channel <NUM>. The third bypass channel <NUM> has a third open-close unit <NUM> that opens and closes the third bypass channel <NUM>.

Each of the first open-close unit <NUM>, the second open-close unit <NUM>, and the third open-close unit <NUM> opens and closes the corresponding channel depending on a pressure difference (differential pressure), and an opening amount of the channel changes in response to the pressure difference (depending on a degree of differential pressure). Such a configuration in which an opening amount of the channel changes in response to a pressure difference can be obtained by, for example, a method using a valve described below. A change in opening amount of the channel in response to a pressure difference changes a flow rate of liquid that flows through a bypass channel in response to the pressure difference.

The term "pressure difference" used herein represents a difference in pressure between an upstream side and a downstream side of the open-close unit. The term "upstream side of the open-close unit" is, for example, an area not only on an upstream side of the open-close unit but also in the vicinity of the open-close unit. Similarly, the term "downstream side of the open-close unit" is, for example, an area not only on a downstream side of the open-close unit but also in the vicinity of the open-close unit. Alternatively, an upstream side of the open-close unit may be an inlet of the open-close unit, and a downstream side of the open-close unit may be an outlet of the open-close unit. In such a case, a pressure difference is a difference in pressure between an inlet and an outlet of each of the first open-close unit <NUM>, the second open-close unit <NUM>, and the third open-close unit <NUM>.

In the present disclosure, a pressure difference when the first open-close unit <NUM> is opened is also referred to as a first predetermined value. A pressure difference when the second open-close unit <NUM> is opened is also referred to as a second predetermined value, and a pressure difference when the third open-close unit <NUM> is opened is also referred to as a third predetermined value.

<FIG> is a cross-sectional view along the line D-D of <FIG>. In <FIG>, the first bypass channel <NUM>, which communicates with the supply main channel <NUM> and the collection main channel <NUM> to connect the supply main channel <NUM> and the collection main channel <NUM>, is illustrated. The first bypass channel <NUM> includes the first open-close unit <NUM> which opens and closes the first bypass channel <NUM>. In <FIG>, the nozzle plate <NUM> is omitted. Other elements including the pressure chamber (the individual liquid chamber) <NUM> are schematically illustrated, and shapes thereof are not limited thereto.

<FIG> are sectional views along the line D-D of <FIG> and illustrating a configuration of a comparative example that is not included in one example of the present disclosure. <FIG> illustrates a case where a pressure difference is small, whereas <FIG> illustrates a case where a pressure difference is large. An arrow in each of <FIG> schematically indicates a flow of liquid. <FIG> are diagrams illustrating a flow rate adjustment mechanism in the comparative example. <FIG> illustrates a case where a pressure difference is small and corresponds to the case illustrated in <FIG>. <FIG> illustrates a case where a pressure difference is large and corresponds to the case illustrated in <FIG>.

In each of <FIG>, a valve <NUM> and a regulation member <NUM> are illustrated. In a case where the valve <NUM> contacts the regulation member <NUM>, a first open-close unit <NUM> is closed. In a case where the valve <NUM> is not in contact with the regulation member <NUM>, the first open-close unit <NUM> is opened. The regulation member <NUM> can be disposed as a separate member or as one portion of the channel.

As illustrated in <FIG> and <FIG>, in a case where a pressure difference is small, the valve <NUM> contacts the regulation member <NUM>, and the first open-close unit <NUM> is closed. Accordingly, in a case where a pressure difference is small, liquid does not flow through a first bypass channel <NUM>. On the other hand, in a case where pressure difference is large as illustrated in <FIG> and <FIG>, an inclination of the valve <NUM> is changed to separate the valve <NUM> from the regulation member <NUM>, and the first open-close unit <NUM> is opened. Accordingly, liquid flows through the first bypass channel <NUM>. In the comparative example, the adjustment mechanism by which an increase in pressure difference increases a flow rate of the first bypass channel <NUM> is provided.

A description is given of an example of bubble discharge at the time of initial filling or maintenance work in the comparative example. First, a supply main channel <NUM> and the downstream side of the supply main channel <NUM> (i.e., a supply branch channel <NUM> and a pressure chamber <NUM>) are filled with liquid. Subsequently, liquid is supplied such that a pressure difference of the first open-close unit <NUM> is increased. Thus, the first open-close unit <NUM> is opened, and a flow rate of the first bypass channel <NUM> is increased. Such an increase in the flow rate causes bubbles, for example, generated or mixed in the supply main channel <NUM> or the supply branch channel <NUM> to move to a collection main channel <NUM>, and the bubbles are discharged to an external circulation path from the collection main channel <NUM>.

When initial filling or maintenance work is performed, in general, a supply amount of liquid is adjusted to increase a flow rate of the entire head, and thus a pressure difference between a supply port <NUM> and a collection port <NUM> increases. Accordingly, in the comparative example, a flow rate of the first bypass channel <NUM> increases at the initial filling or maintenance work as illustrated in <FIG> and <FIG>. In this case, liquid is not adequately supplied to the pressure chamber <NUM>. Consequently, the bubbles inside the pressure chamber <NUM> cannot be discharged adequately. The bubbles remaining inside the pressure chamber <NUM> causes irregularity in an image.

When discharge is performed, on the other hand, a meniscus pressure difference is expected to be small. Accordingly, a supply amount of liquid is adjusted to reduce a pressure difference between the supply port <NUM> and the collection port <NUM>. In the comparative example, as illustrated in <FIG> and <FIG>, a flow rate of the first bypass channel <NUM> is lower at the time of discharge. In this case, a flow rate of the entire head is lower, and bubbles in the supply-side tank <NUM> or the supply main channel <NUM> flows to the pressure chamber <NUM>. Consequently, stable discharge is affected by the bubbles which have flowed to the pressure chamber <NUM>.

In the comparative example, although the bypass channel having the mechanism capable of adjusting a flow rate of liquid is disposed between a supply-side common liquid chamber and a collection-side common liquid chamber, bubbles do not tend be adequately discharged. For example, when initial filling or maintenance work is performed, bubbles inside an individual liquid chamber do not tend to move. Consequently, the bubbles remain inside the individual liquid chamber. Moreover, when discharge is performed, bubbles from a common liquid chamber or a tank may flow to the individual liquid chamber. In such a case, discharge becomes unstable.

In embodiments of the present disclosure, on the other hand, a flow rate adjustment mechanism of the first open-close unit <NUM> is devised. In the embodiments, a flow rate of liquid that flows through the first bypass channel <NUM> is decreased with an increase in a pressure difference between the upstream side and the downstream side of the first open-close unit <NUM>. In other words, a flow rate of the first bypass channel <NUM> changes in response to a pressure difference. Thus, a flow rate decreases as a pressure difference increases, and a flow rate increases as a pressure difference decreases. According to the embodiments, bubble dischargeability at the time of initial filling or maintenance work can be enhanced, and discharge stability at the time of discharge can be enhanced.

<FIG> illustrate one example (a first embodiment) of the present disclosure. Each of <FIG> is a cross sectional view along the line D-D of <FIG>. <FIG> schematically illustrates a case where a pressure difference is small, and <FIG> schematically illustrates a case where a pressure difference is large. An arrow in each of <FIG> schematically indicates a flow of liquid. <FIG> are diagrams illustrating a flow rate adjustment mechanism according to the first embodiment. <FIG> illustrates a case where a pressure difference is small, and corresponds to the case illustrated in <FIG>. <FIG> illustrates a case where a pressure difference is moderate. <FIG> illustrates a case where a pressure difference is large, and corresponds to the case illustrated in <FIG>.

In each of <FIG>, a valve <NUM> and a regulation member <NUM> are illustrated. In a case where the valve <NUM> contacts the regulation member <NUM>, the first open-close unit <NUM> is closed. The first open-close unit <NUM> is configured such that a flow rate is adjusted in response to a pressure difference. In a case where the valve <NUM> is not in contact with the regulation member <NUM>, the first open-close unit <NUM> is opened. The regulation member <NUM> can be disposed as a separate member or as one portion of the channel.

As illustrated in <FIG> and <FIG>, in a case where a pressure difference is small, an inclination of the valve <NUM> is changed to separate the valve <NUM> from the regulation member <NUM>, and the first open-close unit <NUM> is opened. Accordingly, liquid flows through the first bypass channel <NUM>. In the first embodiment, the adjustment mechanism by which reduction in pressure difference increases a flow rate of the first bypass channel <NUM> is provided. On the other hand, in a case where a pressure difference is large as illustrated in <FIG> and <FIG>, the valve <NUM> contacts the regulation member <NUM>, and the first open-close unit <NUM> is closed. Accordingly, liquid does not flow through the first bypass channel <NUM>.

The phrase "a case where a pressure difference is small" represents not only a case where there is no pressure difference but also a case where a pressure difference is smaller than a predetermined value. The phrase "a pressure difference is small" used herein represents a case where a pressure difference is smaller than a first predetermined value, where the first predetermined value is a pressure difference when the first open-close unit <NUM> is opened. Moreover, in a case where a pressure difference is generated, a pressure on the upstream side is increased, whereas a pressure on the downstream side is reduced since liquid is supplied from the upstream side and then collected on the downstream side.

A description is given of an example of bubble discharge at the time of initial filling or maintenance work according to the first embodiment. First, the supply main channel <NUM> and the downstream side of the supply main channel <NUM> (i.e., the supply branch channel <NUM> and the pressure chamber <NUM>) are filled with liquid Subsequently, liquid is supplied such that a pressure difference of the first open-close unit <NUM> is increased. In the first embodiment, as illustrated in <FIG> and <FIG>, the first open-close unit <NUM> is closed, and liquid does not flow through the first bypass channel <NUM> or a flow rate decreases. In such a case in which liquid does not flow through the first bypass channel <NUM> or a flow rate decreases, a flow rate of liquid to the pressure chamber <NUM> increases, so that pressure can be applied to the pressure chamber <NUM>. Accordingly, bubbles inside the pressure chamber <NUM> moves to the collection main channel <NUM>, and then the bubbles are discharged to an external circulation path from the collection main channel <NUM>. Hence, bubbles dischargeability at the time of filling or maintenance work can be enhanced.

The phrase "at the time of filling or maintenance work" used herein represents at the time of filling and/or maintenance work. That is, bubbles dischargeability not only at the time of filling but also even at the time of maintenance work can be enhanced.

At the time of discharge, since a meniscus pressure needs to be reduced, a pressure difference between the supply port <NUM> and the collection port <NUM> is reduced. Accordingly, in the first embodiment, as illustrated in <FIG> and <FIG>, the first open-close unit <NUM> is opened, and a flow rate of liquid in the first bypass channel <NUM> is increased. Thus, a flow rate of the entire head can be increased, thereby enhancing fillability. At the time of printing operation, since liquid can flow through the first bypass channel <NUM>, the liquid can be prevented from excessively flowing into the pressure chamber <NUM>, and a suitable amount of liquid flows into the pressure chamber <NUM>. Thus, bubbles generated or mixed in the supply main channel <NUM> or the supply-side tank <NUM> can be prevented from moving to the pressure chamber <NUM>. Hence, discharge stability at the time of printing operation can be enhanced.

In the printing operation, since a flow rate of the entire head can be increased, a temperature is more easily controlled at the time of circulation. This also enhances fillability and dischargeability. The fillability herein is not limited to fillability of the pressure chamber <NUM>, and fillability of the supply main channel <NUM> and the supply-side tank <NUM> can be enhanced.

For example, a pressure difference between a supply side and a collection side (e.g., a pressure difference between the supply port <NUM> and the collection port <NUM>) is increased at the time of maintenance work (including initial filling), and a pressure difference between the supply side and the collection side is reduced at the time of discharge. For such adjustment of the pressure difference, for example, an air pump is disposed to each of a supply-side tank and a collection-side tank that are externally attached to a discharge head, so that a pressure can be controlled by the air pumps.

<FIG> illustrates one example of a circulation-type ink supply system for description of the aforementioned air pump. However, the present embodiment is not limited thereto. As illustrated in <FIG>, air pumps <NUM> and <NUM> are respectively disposed to the supply-side tank <NUM> and the collection-side tank <NUM>. In <FIG>, arrows schematically indicate one example of control of positive pressure and negative pressure by the air pumps <NUM> and <NUM>. The air pumps <NUM> and <NUM>, a valve <NUM>, and an ink supply pump <NUM> are adjusted to supply ink from an ink tank <NUM>. In addition, the ink can be circulated, and a pressure difference can be adjusted.

In the present embodiment, each of the second open-close unit <NUM> and the third open-close unit <NUM> is configured such that a flow rate of liquid becomes smaller as a pressure difference becomes larger, and a flow rate of liquid becomes larger as a pressure difference becomes smaller, as similar to the first open-close unit <NUM>. With the second open-close unit <NUM> and the third open-close unit <NUM>, a flow rate of liquid becomes smaller as a pressure difference becomes larger so that pressure can be applied to an individual channel and bubbles in the individual channel can be efficiently discharged.

In the present embodiment, each of the second open-close unit <NUM> and the third open-close unit <NUM> is preferably opened by a pressure difference that is larger than a pressure difference by which the first open-close unit <NUM> is opened. That is, where a pressure difference when the first open-close unit <NUM> is opened is a first predetermined value, a pressure difference when the second open-close unit <NUM> is opened is a second predetermined value, and a pressure difference when the third open-close unit <NUM> is opened is a third predetermined value, the second predetermined value is preferably greater than the first predetermined value, and the third pressure difference value is preferably greater than the first predetermined value. If such relations are satisfied, opening of the second open-close unit <NUM> and the third open-close unit <NUM> tends to be more difficult than opening of the first open-close unit <NUM> when a printing operation is performed subsequent to filling, and liquid can be prevented from flowing to a portion other than the nozzle portion. Thus, liquid is supplied to the pressure chamber <NUM> more easily when a printing operation is performed.

In the present embodiment as described above, the first open-close unit <NUM> is configured such that a flow rate of liquid changes in response to a pressure difference, and a flow rate of liquid becomes smaller as a pressure difference becomes larger. As illustrated in <FIG>, the first open-close unit <NUM> in the present embodiment has a cantilever structure, and includes the valve <NUM> including a fixed end 273a on one end side and a free end 273b on the other end side. In a case where the free end 273b of the valve <NUM> and the regulation member <NUM> are in contact with each other, the first open-close unit <NUM> is closed. Such a state is illustrated in <FIG>.

The regulation member <NUM> is disposed in the first bypass channel <NUM> to regulate the free end 273b of the valve <NUM> in a predetermined position.

If a pressure difference between the upstream side and the downstream side of the first open-close unit <NUM> is smaller than a threshold value, the free end 273b of the valve <NUM> is positioned upstream from a position in which the free end 273b contacts the regulation member <NUM> in a direction in which liquid flows. Such a state is illustrated in <FIG>.

The valve <NUM> may be made of, for example, an elastically deformable member.

In the first open-close unit <NUM> according to the present embodiment, if there is no pressure difference or a pressure difference is smaller than a predetermined pressure difference, the first open-close unit <NUM> is opened as illustrated in <FIG>. In <FIG>, the valve <NUM> is widely opened, and a flow rate increases.

An inclination of the valve <NUM> changes as illustrated in <FIG> in order as a pressure difference increases, and the first open-close unit <NUM> is closed. On the other hand, an inclination of the valve <NUM> changes as illustrated in <FIG> in order as a pressure difference decreases, and the first open-close unit <NUM> is opened.

Such a configuration can be expressed differently as follows. That is, where a line connecting the fixed end 273a and the free end 273b of the valve <NUM> is a first line, and a direction in which liquid in the first bypass channel <NUM> flows is a second line, an angle between the first line and the second line changes with an increase in a pressure difference between the upstream side and the downstream side of the first open-close unit <NUM>. If the pressure difference exceeds a threshold value, an angle at which the free end 273b of the valve <NUM> contacts the regulation member <NUM> is provided. Accordingly, in the first open-close unit <NUM>, an increase in the pressure difference can reduce a flow rate more easily.

In this case, however, the valve <NUM> does not need to be a straight member, for example, a plate member. The valve <NUM> may be deformed in a curved manner. Even in such a case, a first line can be defined. Moreover, even in a case where a direction in which liquid flows changes in the first open-close unit <NUM> as illustrated in <FIG>, a second line can be defined. For example, a direction from the left to the right on a paper surface can be defined as a second line. In a state in which a pressure difference is small, the configuration can be expressed as long as inclination of the valve <NUM> to the upstream side in a direction in which liquid flows can be expressed.

Next, another example (a second embodiment) of the present disclosure is described with reference to <FIG>. A discharge head <NUM> according to the second embodiment is illustrated in <FIG> is a sectional view along a supply main channel, and <FIG> is a sectional view along a collection main channel.

The discharge head <NUM> of the second embodiment includes a fourth bypass channel <NUM> that communicates with a supply-side tank <NUM> and a collection-side tank <NUM> to connect the supply-side tank <NUM> and the collection-side tank <NUM>. The fourth bypass channel <NUM> includes a fourth open-close unit <NUM> that opens and closes the fourth bypass channel <NUM>. The fourth open-close unit <NUM> includes a valve. The valve opens and closes the fourth bypass channel <NUM> depending on a pressure difference, and an opening amount of the fourth bypass channel <NUM> changes in response to the pressure difference.

In the second embodiment, a pressure difference by which a first open-close unit <NUM> is opened is greater than a pressure difference by which the fourth open-close unit <NUM> is opened. In the second embodiment, each of a second open-close unit <NUM> and a third open-close unit <NUM> can be opened by a pressure difference that is greater than a pressure difference by which the first open-close unit <NUM> is opened, as similar to the first embodiment. In the second embodiment, where a pressure difference when the first open-close unit <NUM> is opened is a first predetermined value, and a pressure difference when the fourth open-close unit <NUM> is opened is a fourth predetermined value, the first predetermined value is greater than the fourth predetermined value. In the second embodiment, moreover, the fourth open-close unit <NUM> is configured such that an increase in a pressure difference reduces a flow rate of liquid.

In the second embodiment, as similar to the above-described embodiment, when an initial filling is performed, a first bypass channel <NUM> between a supply main channel <NUM> and a collection main channel <NUM> is opened, and then a pressure difference is further increased. Such a further increase in the pressure difference causes the fourth open-close unit <NUM> is opened. With the opening of the fourth open-close unit, a supply-side tank <NUM> and a collection-side tank <NUM> communicate with each other via the fourth bypass channel <NUM>.

Accordingly, liquid flows from the supply-side tank <NUM> to the collection-side tank <NUM>, and the collection-side tank <NUM> is reliably filled with liquid.

Therefore, first, a pressure chamber <NUM> is filled with liquid by low pressure circulation, and then a circulation pressure is gradually increased. Such a gradual increase in the circulation pressure opens a bypass channel between a common main channel and a common branch channel, a bypass channel between common main channels, and a bypass channel between tanks in order, thereby filling the common branch channel, the common main channel, and the collection-side tank with liquid in order.

Herein, the fourth bypass channel <NUM> communicating with each of the supply-side tank <NUM> and the collection-side tank <NUM> may be a channel that is constantly opened. In such a case, liquid flows from the supply-side tank <NUM> to the collection-side tank <NUM> from the beginning when initial filling is performed.

Consequently, liquid needs to be supplied by large pressure to discharge bubbles inside channels such as the supply main channel <NUM>, a supply branch channel <NUM>, the collection main channel <NUM>, a collection branch channel <NUM>, the pressure chamber <NUM>, an individual supply channel <NUM>, and an individual collection channel <NUM>.

In the second embodiment, on the other hand, since second and third bypass channels <NUM> and <NUM>, the first bypass channel <NUM>, and the fourth bypass channel <NUM> are opened in order, a circulation differential pressure is gradually increased after the pressure chamber <NUM> is filled by low pressure circulation. Such a gradual increase in the circulation differential pressure enables a bypass channel between the common main channel and the common branch channel, a bypass channel between the common main channels, and a bypass channel between the tanks to be opened in order, thereby filling the common branch channel, the common main channel, and the tank with liquid in order.

The fourth bypass channel <NUM> can be disposed in a position as illustrated in <FIG>. However, the fourth bypass channel <NUM> is preferably disposed in the uppermost portion of the supply-side tank <NUM> and the collection-side tank <NUM>. <FIG> are diagrams illustrating other examples of the fourth bypass channel <NUM>. <FIG> is a cross-sectional view along a supply main channel, and <FIG> is a cross-sectional view along a collection main channel. The arrangement of the fourth bypass channel <NUM> in the uppermost portion of the tanks as illustrated in <FIG> enables bubbles in an upper portion of the tanks to be removed by circulation.

Next, another example (a third embodiment) of the present disclosure is described with reference to <FIG> is a plan view illustrating a channel arrangement of a discharge head <NUM> according to the third embodiment.

The discharge head <NUM> of the third embodiment includes a first bypass channel <NUM> that communicates with each of a supply main channel <NUM> and a collection main channel <NUM> to connect the supply main channel <NUM> and the collection main channel <NUM>, as similar to the above-described embodiments. The first bypass channel <NUM> includes a first open-close unit <NUM> that opens and closes the first bypass channel <NUM>.

The third embodiment differs from the above-described embodiments in having a fifth bypass channel 261a on the supply side and a fifth bypass channel 261b on the collection side. The fifth bypass channels 261a and 261b communicate with a supply branch channel <NUM> and a collection branch channel <NUM> that are adjacent to each other to connect the supply branch channel <NUM> and the collection branch channel <NUM>.

Thus, for example, two fifth bypass channels 261a communicating with respective two supply branch channels <NUM> disposed on both sides of one collection branch channel <NUM> are disposed. Similarly, two fifth bypass channels 261b communicating with two respective collection branch channels <NUM> disposed on both sides of one supply branch channel <NUM> are disposed.

On a side nearer to the entry to the supply branch channel <NUM> from the supply main channel <NUM> and on a side nearer to the supply main channel <NUM> relative to a supply port <NUM> and a collection port <NUM>, the fifth bypass channel 261b communicates with each of the supply branch channel <NUM> and the collection branch channel <NUM> to connect the supply branch channel <NUM> and the collection branch channel <NUM>.

On a side nearer to the entry to the collection main channel <NUM> from the collection branch channel <NUM> and on a side nearer to the collection main channel <NUM> relative to the supply port <NUM> and the collection port <NUM>, the fifth bypass channel 261a communicates with each of the supply branch channel <NUM> and the collection branch channel <NUM> to connect the supply branch channel <NUM> and the collection branch channel <NUM>.

The fifth bypass channel 261a includes a fifth open-close unit 262a that opens and closes the fifth bypass channel 261a. Moreover, the fifth bypass channel 261b includes a fifth open-close unit 262b that opens and closes the fifth bypass channel 261b.

Similar to the first open-close unit <NUM>, any of the fifth open-close units 262a and 262b includes a valve that opens and closes a channel depending on a pressure difference and an opening amount of the channel changes depending on a degree of the pressure difference.

In the present embodiment, any of the fifth open-close units 262a and 262b can open the channel by using a pressure difference that is smaller than a pressure difference used for the first open-close unit <NUM>, and the fifth bypass channels 261a and 261b are opened by using a pressure difference that is smaller than a pressure difference used for the first bypass channel <NUM>.

Next, liquid filling to the discharge head <NUM> having such a configuration is described. When the discharge head <NUM> is initially filled with liquid, bubbles inside channels such as a supply main channel <NUM>, a supply branch channel <NUM>, a collection main channel <NUM>, a collection branch channel <NUM>, a pressure chamber <NUM>, an individual supply channel <NUM>, and an individual collection channel <NUM> need to be discharged to a collection-side tank <NUM> or a collection port <NUM>, as described above.

In the present embodiment, when a channel of the discharge head <NUM> is filled with liquid, first, liquid is supplied from the supply-side tank <NUM> to the supply main channel <NUM> via a supply port <NUM> by using a pressure that provides a pressure difference by which the fifth open-close units 262a and 262b are closed. Herein, each of the first open-close unit <NUM>, the fifth open-close units 262a and 262b is being closed, and the first bypass channel <NUM>, the fifth bypass channels 261a and 261b are closed.

Accordingly, the liquid supplied to the supply main channel <NUM> flows from the supply branch channel <NUM> and reaches the collection branch channel <NUM> via the individual supply channel <NUM>, the pressure chamber <NUM>, and the individual collection channel <NUM>. Then, the liquid flows to the collection main channel <NUM> from the collection branch channel <NUM>.

Subsequently, a pressure of the liquid to be supplied to the supply main channel <NUM> from the supply-side tank <NUM> via the supply port <NUM> is increased, and a pressure difference between the supply branch channel <NUM> and the collection branch channel <NUM> becomes a fifth predetermined value or more (the fifth predetermined value < a first predetermined value). Thus, the fifth open-close units 262a and 262b are opened. Such opening of the fifth open-close units 262a and 262b opens the fifth bypass channels 261a and 261b, and the supply branch channel <NUM> and the collection branch channel <NUM> communicate with each other via the fifth bypass channels 261a and 261b.

Accordingly, the liquid which has entered the supply branch channel <NUM> from the supply main channel <NUM> flows from the supply branch channel <NUM> to the upstream side of the collection branch channel <NUM> via the fifth bypass channel 261a, and then flows to the downstream side of the collection branch channel <NUM> via the fifth bypass channel 261b.

Herein, bubbles remaining on the downstream side within the supply branch channel <NUM> are discharged to the downstream side of the collection branch channel <NUM> via the fifth bypass channel 261a. Moreover, bubbles remaining on the upstream side within the collection branch channel <NUM> are transferred to the upstream side within the collection branch channel <NUM> by liquid that flows in from the fifth bypass channel 261a. Hence, the supply branch channel <NUM> and the collection branch channel <NUM> are reliably filled with liquid.

Then, a pressure of the liquid to be supplied to the supply main channel <NUM> from the supply-side tank <NUM> via the supply port <NUM> is increased, and a pressure difference between the supply main channel <NUM> and the collection branch channel <NUM> becomes a third predetermined value or more. Thus, the first open-close unit <NUM> is opened. Such opening of the first open-close unit <NUM> opens the first bypass channel <NUM>, and the supply main channel <NUM> and the collection main channel <NUM> communicate with each other via the first bypass channel <NUM>.

Accordingly, the liquid which have been supplied to the supply main channel <NUM> flows to the collection main channel <NUM> via the first bypass channel <NUM>. Herein, bubbles remaining inside the supply main channel <NUM> are discharged to the collection main channel <NUM>, and the supply main channel <NUM> is reliably filled with liquid.

Then, the bubbles which have been transferred to the collection main channel <NUM> are transferred to the collection-side tank <NUM> via the supply port <NUM>, and the collection main channel <NUM> is reliably filled with liquid.

Even in the present embodiment, a fourth bypass channel <NUM> and a fourth open-close unit <NUM> can be disposed by application of the above-described example. The fourth bypass channel <NUM> communicates with the supply-side tank <NUM> and the collection-side tank <NUM> to connect the supply-side tank <NUM> and the collection-side tank <NUM>, and the fourth open-close unit <NUM> opens and closes the fourth bypass channel <NUM>.

Next, one example of a printing apparatus <NUM> as a discharge apparatus according to the present disclosure is described with reference to <FIG> is a schematic view illustrating the printing apparatus <NUM>, and <FIG> is a plan view illustrating a discharge unit of the printing apparatus <NUM>.

The printing apparatus <NUM> is an apparatus that discharges liquid, and includes a loading unit <NUM> to which sheets P are loaded, a pre-processing unit <NUM>, a printing unit <NUM>, a drying unit <NUM>, and an ejection unit <NUM>.

In the printing apparatus <NUM>, the pre-processing unit <NUM> applies (coats) pre-processing liquid as necessary to a sheet P that is loaded (supplied) from the loading unit <NUM>, and the printing unit <NUM> performs a required printing operation by applying liquid to the sheet P. The drying unit <NUM> dries the liquid adhering to the sheet P, and then the resultant sheet P is ejected to the ejection unit <NUM>.

The loading unit <NUM> includes a loading tray <NUM> (a lower loading tray 11A and an upper loading tray 11B) in which a plurality of sheets P is stored, and a feed device <NUM> (a lower feed device 12A and an upper feed device 12B) that separates and feeds the sheets P one by one from the loading tray <NUM>. The loading unit <NUM> supplies the sheet P to the pre-processing unit <NUM>.

The pre-processing unit <NUM> includes a coating unit <NUM> as a processing-liquid applying unit that applies processing liquid to a print surface of the sheet P. The processing liquid has, for example, an effect of preventing ink from bleeding through the sheet P by aggregating the ink.

The printing unit <NUM> includes a drum <NUM> as a bearer (a rotator) and a liquid discharger <NUM>. The drum <NUM> rotates with a circumferential surface bearing the sheet P, and the liquid discharger <NUM> discharges liquid toward the sheet P on the drum <NUM>.

In addition, the printing unit <NUM> includes delivery drums <NUM> and <NUM>. The delivery drum <NUM> receives the sheet P fed from the pre-processing unit <NUM> to deliver the sheet P toward the drum <NUM>. The delivery drum <NUM> receives the sheet P conveyed by the drum <NUM> to deliver the sheet P to the drying unit <NUM>.

When the sheet P is conveyed from the pre-processing unit <NUM> to the printing unit <NUM>, a leading end of the sheet P is gripped by a gripper (a sheet gripper) disposed to the delivery drum <NUM>, and the sheet P is conveyed with rotation of the delivery drum <NUM>. The sheet P conveyed by the delivery drum <NUM> is delivered to the drum <NUM> in a position opposite the drum <NUM>.

The drum <NUM> has a surface on which a gripper (a sheet gripper) is disposed, and the leading end of the sheet P is gripped by the gripper. A plurality of suction holes is dispersedly formed on the surface of the drum <NUM>, and a suction airflow inward from a required suction hole of the drum <NUM> is generated by a suction unit.

Then, the leading end of the sheet P delivered from the delivery drum <NUM> to the drum <NUM> is griped by the sheet gripper, and the sheet P is conveyed with rotation of the drum <NUM> with the drum <NUM> bearing the sheet P attracted to the drum <NUM> by the suction airflow generated by the suction unit.

The liquid discharger <NUM> includes discharge units <NUM> (33A through 33D) as dischargers. For example, the discharge units 33A, 33B, 33C, and 33D respectively discharge cyan (C) liquid, magenta (M) liquid, yellow (Y) liquid, and black liquid (K). In addition, the liquid discharger <NUM> can use a discharge unit that discharges special liquid such as white liquid and gold (silver) liquid.

The discharge unit <NUM> is, for example, a full line head as illustrated in <FIG>, and includes a plurality of discharge heads <NUM> arranged in a staggered pattern on a base member <NUM>. Each of the discharge head <NUM> includes a plurality of nozzles <NUM> that are arranged in a two-dimensional matrix manner.

A discharge operation of each discharge unit <NUM> of the liquid discharger <NUM> is controlled based on a driving signal corresponding to print information. When the sheet P on the drum <NUM> passes an area opposite the liquid discharger <NUM>, each color of liquid is discharged from the discharge unit <NUM>, and an image corresponding to the print information is printed.

The drying unit <NUM> dries the liquid which has adhered to the sheet P in the printing unit <NUM>. The use of the drying unit <NUM> evaporates a liquid substance such as moisture in the liquid, and a colorant contained in the liquid is fixed on the sheet P. Moreover, the use of the drying unit <NUM> prevents the sheet P from being curled.

A reverse unit <NUM> reverses a sheet P that has passed the drying unit <NUM> when duplex printing is performed on the sheet P. The reversed sheet P is fed backward to the upstream side relative to the delivery drum <NUM> via a conveyance path <NUM> of the printing unit <NUM>.

The ejection unit <NUM> includes an ejection tray <NUM> on which a plurality of sheets P is to be stacked. The sheets P conveyed from the drying unit <NUM> via the reverse unit <NUM> are sequentially stacked and held on the ejection tray <NUM>.

Liquid to be discharged by such a discharge head <NUM> is not particularly limited as long as liquid has surface tension and viscosity enabling the liquid to be discharged from the discharge head <NUM>. Liquid preferably has a viscosity of <NUM> mPa· s or less under normal temperature and normal pressure or by heating or cooling. More particularly, examples of liquid include an emulsion, a suspension, and a solution including: a solvent such as water and an organic solvent; a colorant such as a dye and a pigment; a functionality adding material such as a polymerizable compound, a resin, and a surface-active agent; a biocompatible material such as a deoxyribonucleic acid (DNA), an amino acid, protein, and calcium; and an edible material such as a natural coloring agent. Such liquid can be used for, for example, inkjet ink, a surface treatment liquid, a liquid for forming an electronic circuit resist pattern or a component of an element such as an electronic element and a light emitting element, and a three-dimensional shaping liquid.

Herein, an example of the liquid (the three-dimension shaping liquid) to be used for formation of a three-dimensional object is a hydrogel formation material for formation of a three-dimensional structure to be used, for example, in treatment manipulation training.

The hydrogel formation material contains water and a polymerizable monomer, and preferably contains a mineral and an organic solvent. In addition, the hydrogel formation material can contain a polymerization initiator and other components as necessary. The polymerizable monomer is a compound having one or more unsaturated carbon-carbon bonds, and is preferably polymerized by activation energy rays such as ultraviolet rays and electron beams.

Examples of the polymerizable monomers include a monofunctional monomer and a multifunctional monomer. These may be used alone or in combination. Examples of the multifunctional monomers include a bifunctional monomer, a trifunctional monomer, and a tetra or higher functional monomer.

The mineral is not limited to any particular mineral. Although a mineral can be appropriately selected for each purpose, a clay mineral is preferred since a main component of the hydrogel is water. Furthermore, a layered clay mineral that is uniformly dispersible in water at a primary crystal level is preferred, and a water-swellable layered clay mineral is more preferred.

An example of the organic solvent includes a water-soluble organic solvent. Water solubility of the water-soluble organic solvent means that the organic solvent is soluble at <NUM>% by mass or greater relative to water.

The water-soluble organic solvent is not particularly limited, and can be appropriately selected for each purpose. Examples of water-soluble organic solvents include: alkyl alcohols having one or more and four or less carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; amides such as dimethylformamide and dimethyl acetamide; ketone or ketone alcohols such as acetone, methyl ethyl ketone, and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyhydric alcohol such as ethylene glycol, propylene glycol, <NUM>, <NUM>-propanediol, <NUM>, <NUM>-butanediol, <NUM>, <NUM>-butanediol, <NUM>, <NUM>-butanediol, diethylene glycol, triethylene glycol, <NUM>,<NUM>,<NUM>-hexanetriol, thioglycol, hexylene glycol, and glycerin; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; lower alcohol ethers of polyhydric alcohol such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether; alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine; and other such as N-Methyl-<NUM>-pyrrolidone, <NUM>-pyrrolidone, and <NUM>,<NUM>-dimethyl-<NUM>-imidazolidinone. These may be used alone or in combination. Among such organic solvents, polyhydric alcohol, glycerin, and propylene glycol are preferred in terms of moisture-retaining property, and glycerin and propylene glycol are more preferred.

The polymerization initiator is not particularly limited, and can be appropriately selected for each purpose. Examples of polymerization initiators include a photopolymerization initiator and a thermal polymerization initiator. As for the photopolymerization initiator, an optional material that generates a radical by using light that is emitted (particularly, an ultraviolet (UV) ray having a wavelength of <NUM> to <NUM>) can be used.

In a case where a hydrogel formation material is used to form a three-dimensional object, a UV emitting device is disposed to irradiate a discharged hydrogel formation material with UV rays, so that the hydrogel formation material is hardened, and a three-dimensional object is formed.

While agitating <NUM> parts by mass of ion exchanged water that had undergone pressure reduction and deaeration for <NUM> minutes, <NUM> parts by mass of synthetic hectorite (Laponite-XLG manufactured by Rockwood Inc. ) having a composition of [Mg<NUM>Li<NUM>. <NUM>Si<NUM>O<NUM>(OH)<NUM>]Na-<NUM> as a layered clay mineral was added little by little and agitated. In addition, <NUM> parts by mass of etidronic acid (manufactured by Tokyo Chemical Industry Co. ) was added and agitated, so that dispersion liquid was produced.

Subsequently, <NUM> parts by mass of acryloylmorpholine (manufactured by KJ Chemicals Corporation) from which polymerization inhibitor had been removed by passing through an activated alumina column, and <NUM> parts by mass of methylenebisacrylamide (manufactured by Tokyo Chemical Industry Co. ) were added as polymerizable monomer to the dispersion liquid. Furthermore, <NUM> mass of glycerin (manufactured by Sakamoto Yakuhin Kogyo Co. ) and <NUM> parts by mass of N,N,N',N'-Tetramethylethylenediamine (manufactured by Tokyo Chemical Industry Co. ) were mixed, so that a hydrogel formation material was obtained.

The discharge head <NUM> according to the present disclosure, as described above, can be used for an inkjet method for optional arrangement of cells to artificially form an organism containing cells, and can discharge a cell suspension (cell ink).

The cell suspension (cell ink) at least contains cells and a cell drying inhibitor. Moreover, the cell suspension (cell ink) contains a dispersant that causes cells to be dispersed, and can contain other additive materials such as a dispersing agent and a pH adjuster as necessary.

A type of the cell is not particularly limited, and can be appropriately selected for each purpose. Every cell can be used regardless of whether, for example, a cell is taxonomically a eukaryotic cell, a procaryotic cell, a multicellular organism cell, or a unicellular organism cell. These may be used alone or in combination.

Examples of the eukaryotic cells include an animal cell, an insect cell, a plant cell, and a fungus. These may be used alone or in combination. In these examples, the animal cell is preferred. In a case where cells form a cell aggregate, an adherent cell having cell adhesiveness by which cells adhere to each other and are not isolated unless a physicochemical process is performed is more preferred.

The cell drying inhibitor has a function of covering a surface of a cell to inhibit dryness of the cell. Examples of the cell drying inhibitors include polyhydric alcohols, gel polysaccharides, and a protein selected from an extracellular matrix.

The dispersant is preferably a buffer solution or a culture medium for cell culture. The culture medium contains components necessary for formation and maintenance of a cell organism, and is a solution that prevents dryness and arranges an external environment such as an osmotic pressure. A solution or medium known as a culture medium can be appropriately selected and used. In a case where cells do not need to be constantly immersed in a culture medium, the culture medium can be appropriately removed from a cell suspension. The buffer solution adjusts pH depending on a cell or a purpose, and a known buffer solution may be appropriately selected and used.

A green fluorescent dye (Cell Tracker Green manufactured by Life Technologies Ltd. ) was dissolved in dimethyl sulphoxide (DMSO) at a concentration of <NUM> mmol/L(mM), and the resultant solution was mixed with serum-free Dulbecco's modified Eagle medium (manufactured by Life Technologies Ltd. Thus, a green fluorescent dye-containing serum-free medium having a concentration of <NUM>µmol/L(µM) was prepared.

Subsequently, <NUM> of the green fluorescent dye-containing serum-free medium was added into a dish having a cultured NIH/3T3 cells (Clone <NUM>, JCRB Cell Bank), and the resultant cells were cultured for <NUM> minutes in an incubator (KM-CC17RU2 manufactured by Panasonic Corporation, <NUM>, <NUM> % by volume CO2 environment).

Then, a supernatant was removed using an aspirator. Five milliliters of phosphate buffered saline (hereinafter also referred to as PBS (-), manufactured by Life Technologies Ltd. ) was added to the dish, and the PBS (-) was removed by suction using an aspirator to clean the surface. After cleaning with the PBS (-) was repeated twice, <NUM> of trypsin-ethylene diamine tetra acetic acid (EDTA) solution (manufactured by Life Technologies Ltd. ) was added per dish. The trypsin-EDTA solution added herein was <NUM>% by mass of trypsin with <NUM>% by mass of EDTA.

Next, the resultant solution containing the cells was heated for <NUM> minutes in the incubator, and the cells were exfoliated from the dish. Subsequently, <NUM> of D-MEM containing <NUM>% by mass of a fetal bovine serum (hereafter also referred to as FBS) and <NUM>% by mass of an antibiotic (Antibiotic-Antimycotic Mixed Stock Solution (100x), manufactured by NACALAI TESQUE, INC. ) was added.

Next, a cell suspension in which trypsin had been devitalized was transferred to a single <NUM>-mL centrifuge tube. The cell suspension in the centrifuge tube was centrifuged (at <NUM>,<NUM> rpm for <NUM> minutes at <NUM> by a machine named H-19FM manufactured by KOKUSAN Co. ), and a supernatant was removed using an aspirator. After the removal, <NUM> of D-MEM containing <NUM>% by mass of FBS and <NUM>% by mass of antibiotic was added to the centrifuge tube, and pipetting was gently performed to disperse the cells. Hence, a cell suspension was acquired.

After <NUM>µL of the cell suspension was extracted into an Eppendorf tube and <NUM>µL of a culture medium was added into the tube, <NUM>µL of the resultant cell suspension was extracted into another Eppendorf tube. Then, <NUM>µL of a trypan blue stain solution in an amount of <NUM>% by mass was added, and pipetting was performed. From the stained cell suspension, <NUM>µL of the suspension was removed and placed on a plastic slide made of polymethyl methacrylate (PMMA). The number of cells was counted using a counter named Countess Automated Cell Counter (manufactured by Invitrogen), so that a cell suspension containing cells the cell number of which had been counted was obtained. Moreover, a PBS (-) was used as a dispersant. Glycerin (a molecular biology grade, manufactured by Wako Pure Chemical Industries, Ltd. ) as a cell drying inhibitor was dissolved in the PBS (-) so as to have a mass ratio of <NUM>% by mass, and an NIH/3T3 cell suspension was dispersed in a dispersant so as to be <NUM> × <NUM> cell/mL Accordingly, a cell ink was obtained.

Claim 1:
A discharge head (<NUM>) comprising:
multiple nozzles (<NUM>) from each of which a liquid is discharged;
multiple pressure chambers (<NUM>) respectively communicating with the multiple nozzles (<NUM>);
multiple supply branch channels (<NUM>) each communicating with two or more of the multiple pressure chambers (<NUM>) to supply the liquid to the two or more of the pressure chambers (<NUM>);
multiple collection branch channels (<NUM>) each communicating with two or more of the multiple pressure chambers (<NUM>) to collect the liquid from the two or more of the pressure chambers (<NUM>);
a supply main channel (<NUM>) communicating with each of the multiple supply branch channels (<NUM>) to supply the liquid to the multiple supply branch channels (<NUM>);
a collection main channel (<NUM>) communicating with each of the multiple collection branch channels (<NUM>) to collect the liquid from the multiple collection branch channels (<NUM>);
a first bypass channel (<NUM>) communicating with each of the supply main channel (<NUM>) and the collection main channel (<NUM>) to connect the supply main channel (<NUM>) and the collection main channel (<NUM>); and
a first open-close unit (<NUM>) configured to:
openably close the first bypass channel (<NUM>); and characterized in that the first open-close unit (<NUM>) is also configured to
decrease a flow rate of the liquid flowing through the first bypass channel (<NUM>) with an increase in a first pressure difference between an upstream side and a downstream side of the first open-close unit (<NUM>).