Head module and liquid ejection apparatus

Abstract

A head module includes a head, a driver IC, a heat spreader, a holder and a heat insulator. The head ejects liquid in response to the driver IC. The heat spreader is in thermal communication with the driver IC. The holder supports the head. The heat insulator is located to thermally isolate the heat spreader and the holder.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2016-255562 filed on Dec. 28, 2016, the content of which is incorporated herein by reference in its entirety.

FIELD OF DISCLOSURE

The disclosure relates to a head module and a liquid ejection apparatus including the head module.

BACKGROUND

There is a known semiconductor module including a chip-mounted board and a heat sink, as disclosed in, for example, FIGS. 1-4 of Japanese Laid-Open Patent Publication No. 11-330328. A surface of the chip-mounted board is in intimate contact with the heat sink via thermal grease. In the semiconductor module, the heat sink dissipates heat produced by the chip-mounted board. A resin-made or plastic enclosure case is directly bonded to the heat sink.

SUMMARY

In the semiconductor module, the enclosure case is directly bonded to the heat sink, so that the enclosure case may deform due to the heat from the heat sink. The deformed enclosure case may create a space or gap, between the heat sink and the enclosure case. For example, if such semiconductor module is employed in a head module configured to eject liquid, the liquid fragmented into mist during ejection may enter a space between the heat sink (e.g., a heat spreader) and the enclosure case (e.g., a holder), leading to a short-circuit failure in the chip-mounted board (e.g., a driver IC).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a printer in an illustrative embodiment according to one or more aspects of the disclosure, illustrating relevant interior components of the printer.

FIG. 2 is a plan view of a head unit of the printer.

FIG. 3 is a perspective view of a head module of the printer.

FIG. 4 is an exploded perspective view of the head module of the printer.

FIG. 5 is a partial cross-sectional view of a head module of the printer.

FIG. 6 is a side view of the head module viewed in the direction of the arrow VI of FIG. 3.

FIG. 7 is a side view of the head module viewed in the direction of the arrow VII of FIG. 3.

FIG. 8 is a cross-sectional view of the head module taken along the line VIII-VIII of FIG. 6.

FIG. 9 is a cross-sectional view of the head module taken along the line IX-IX of FIG. 7.

DETAILED DESCRIPTION

As depicted in FIG. 1, a printer 1 includes four head units 10, a platen 20, roller pairs 30 and 40, and a controller 50. The roller pairs 30 and 40, each include a pair of rollers. The controller 50 is configured to control the pair of rollers of each roller pair 30 and 40 to rotate in opposite directions while the pair of rollers holds a sheet 100 therebetween and to convey the sheet 100 in a conveying direction. The four head units 10 and the platen 20 are located between the roller pair 30 and the roller pair 40 in the conveying direction. The platen 20 is located below the four head units 10. The four head units 10 are spaced equi-distantly in the conveying direction. The controller 50 is configured to control each head unit 10 to eject one of different color inks. The head units 10 eject ink while the sheet 100 passes between the head units 10 and the platen 20. The ink landing on the sheet 100 forms an image on the sheet 100.

Each of the four head units 10 has the same or similar configuration. Accordingly, one head unit 10 is described in detail below. The head unit 10 is of a line type in which the head unit 10 fixed at a prescribed position ejects ink to the sheet 100. The head unit 10 is elongated in a main scanning direction which is perpendicular to the conveying direction and is parallel to a sheet support surface of the platen 20.

As depicted in FIG. 2, the head unit 10 includes nine head modules 10m and a frame 10f that supports the nine head modules 10m. The nine head modules 10m are arranged in a staggered manner along the main scanning direction. Each of the nine head modules 10m has the same or similar configuration. Accordingly, one head module 10m is described in detail below. The head module 10m has a plurality of orifices 11x formed in a lower surface thereof.

As depicted in FIGS. 3 and 4, the head module 10m includes a head 11, a pair of driver ICs 12, a holder 13, a heat spreader 14, a heat insulator 15, a support plate 16, and four pipes 17. The holder 13 supports the head 11. The holder 13 is made of, for example, epoxy resin. The heat spreader 14 is thermally connected to the driver ICs 12. The heat spreader 14 is made of metal, such as aluminum, having a relatively high thermal conductivity. The heat insulator 15 is disposed between the heat spreader 14 and the holder 13, and is in contact with the heat spreader 14 and the holder 13. The support plate 16 supports the holder 13. The support plate 16 is made of, for example, stainless steel (e.g., SUS430). The support plate 16 is supported by the frame 10f (refer to FIG. 2).

As depicted in FIG. 4, the holder 13 has six screw holes 13h. The head 11 has also six screw holes 11h (one of which is hidden and not depicted in FIG. 4). The support plate 16 has also six screw holes 16h (one of which is depicted in FIG. 9). A screw 19 is inserted into a first screw hole 11h of the head 11, a first screw hole 13h of the holder 13, and a first screw hole 16h of the support plate 16. Similarly, another screw 19 is inserted into a second screw hole 11h of the head 11, a second screw hole 13h of the holder 13, and a second screw hole 16h of the support plate 16. In short, six screws 19 are each inserted into a respective one of the six screw holes 11h of the head 11, the six screw holes 13h of the holder 13, and the six screw holes 16h of the support plate 16. The head 11, the holder 13 and the support plate 16 are fixed relative to one another by screwing the six screws 19 into the head 11, the holder 13 and the support plate 16 in their thickness direction.

As depicted in FIGS. 3-5, the head 11 includes a flow channel substrate 11m, an actuator 11n, and a head frame 11f.

The flow channel substrate 11m has a lower surface (e.g., an ejection surface 11a) that is the lowest portion of the head module 10m. As depicted in FIGS. 2 and 5, the flow channel substrate 11m has a plurality of orifices 11x formed in the ejection surface 11a. As depicted in FIG. 2, the orifices 11x are arranged into four orifice rows 11xr. The four orifice rows 11xr, each extending in the main scanning direction, are arranged along the conveying direction. The flow channel substrate 11m has four common channels 11y and a plurality of individual channels 11z formed therein. The number of the individual channels 11z is the same as the number of the orifices 11x. Each of the individual channels 11z fluidly communicates with a respective one of the orifices 11x. Each of the four common channels fly is provided in correspondence with a respective one of the four orifice rows 11xr. The four common channels 11y, each extending in the main scanning direction, are arranged along the conveying direction. Each of the common channels 11y fluidly communicates with the individual channels 11z communicating with the orifices 11x of a corresponding one of the orifice rows 11xr. Each of the four common channels 11y fluidly communicates with a corresponding one of ink tanks (not depicted) via a respective one of the four pipes 17. The individual channel 11z extends from an outlet of the common channel fly to the orifice 11x, via a pressure chamber 11z1. Pressure chambers 11z1 are formed into an upper surface of the flow channel substrate 11m.

The actuator 11n is located at a generally central portion of the upper surface of the flow channel substrate 11m. The actuator 11n includes a diaphragm 11n1, a piezoelectric layer 11n2, a common electrode 11n3, and a plurality of individual electrodes 11n4. The diaphragm 11n1 is disposed on the upper surface of the flow channel substrate 11m, covering the plurality of pressure chambers 11z1. The piezoelectric layer 11n2 is disposed above the diaphragm 11n1. The common electrode 11n3 is disposed between the diaphragm 11n1 and the piezoelectric layer 11n2. The plurality of individual electrodes 11n4 is disposed on an upper surface of the piezoelectric layer 11n2. The common electrode 11n3 extends across the plurality of pressure chambers 11z1. Each of the individual electrodes 11n4 faces a respective one of the pressure chambers 11z1. The common electrode 11n3 is grounded. A voltage may be applied by the driver IC 12 to the individual electrode 11n4. The voltage may cause particular portions of the diaphragm 11n1 and the piezoelectric layer 11n2 between the individual electrode 11n4 and the pressure chamber 11z1 to deform toward the pressure chamber 11z1. This may reduce the volumetric capacity of the pressure chamber 11z1, thereby applying pressure to ink in the pressure chamber 11z1. The pressure may cause the ink to be ejected through the orifice 11x.

The driver ICs 12, electrically connected to the actuator 11n, drive the actuator 11n. The driven actuator 11n may apply energy to ink in the individual channels 11z to eject ink through the orifices 11x.

As depicted in FIG. 4, the head frame 11f is frame-shaped. The head frame 11f is fixed on the upper surface of the flow channel substrate 11m and outside a region where the plurality of orifices 11x are formed (the region occupied by the orifices 11x as depicted in FIG. 2). In other words, the plurality of orifices 11x is not formed under the frame-shaped portion of the head frame 11f. The head frame 11f has one opening 11fx and four through-holes 11fy. The opening 11fx and the through-holes 11fy extend through the head frame 11f in its thickness direction. As depicted in FIG. 2, each of the four through-holes 11fy fluidly communicates with a corresponding one of the four common channels 11y.

The actuator 11n and a chip on film (“COF”) 11c, as depicted in FIG. 4, are disposed in the opening 11fx. The COF 11c has flexibility and includes a bonding portion 11c1 and a pair of folded portions 11c2. The bonding portion 11c1 is disposed at an upper surface of the actuator 11n and includes a plurality of terminals (not depicted). Each of the terminals of the bonding portion 11c1 is electrically connected to a corresponding one of terminals of the individual electrodes 11n4 formed on an upper surface of the actuator 11n. The folded portions 11c2 extend upward from ends of the bonding portion 11c1 and bend toward each other. Each folded portion 11c2 faces the upper surface of the actuator 11n with a space therebetween. Each of the folded portions 11c2 has a respective one of the driver ICs 12 disposed at an upper surface thereof.

As depicted in FIG. 4, opposing end portions of the folded portions 11c2 are each connected to a horizontal portion 11d1 of a flexible printed circuit (“FPC”) 11d. The FPC 11d includes the horizontal portion 11d1 and a vertical portion 11d2. The horizontal portion 11d1 has a plurality of electrical terminals (not depicted). In correspondence with the electrical terminals of the horizontal portion 11d1, each of the folded portions 11c2 has a plurality of electrical terminals at an end portions thereof. Each electrical terminal of the horizontal portion 11d1 is electrically connected to a corresponding electrical terminal of the folded portions 11c2. The vertical portions 11d2 extends upward from one end of the horizontal portion 11d1. The vertical portion 11d2 is connected to the controller 50 (refer to FIG. 1). A control signal from the controller 50 is input to the driver ICs 12, via the FPC 11d and the COF 11c. Each of the driver ICs 12 is configured to generate a drive signal based on the control signal, and to output the drive signal to the actuator 11n.

As depicted in FIGS. 8 and 9, a pressing member 11p and a biasing member 11s are disposed in the opening 11fx. The pressing member 11p is disposed on an upper surface of the bonding portion 11c1 at a peripheral end of the bonding portion 11c1. The bonding portion 11c1 is located between the pressing member 11p and the actuator 11n. The pressing member 11p may prevent the bonding portion 11c1 from separating from the actuator 11n. The pressing member 11p has two projections 11p1 formed at an upper surface thereof. The projections 11p1 are in contact with the biasing member 11s. The biasing member 11s is supported by the pressing member 11p via the two projections 11p1. In other words, the pressing member 11p supports the biasing member 11s from below via the two projections 11p1. The biasing member 11s includes a pair of elastic portions 110. Each of the elastic portions 11s1 is in contact with a particular portion of a lower surface of a respective one of the folded portions 11c2. The particular portion corresponds to a position where the driver IC is located. The elastic portions 11s1 urge the driver ICs 12 upward (e.g., in a direction in which the driver ICs 12 approach the heat spreader 14).

As depicted in FIG. 4, the holder 13 is frame-shaped and fixed to an upper surface of the head frame 11f. A lower surface of the holder 13 is in contact with the upper surface of the head frame 11f. The holder 13 has one opening 13x and four through-holes 13y. The opening 13x and the four through-holes 13y extend through the holder 13 in its thickness direction. As depicted in FIG. 9, the folded portions 11c2 and the driver ICs 12 are disposed in the opening 13x. Further, as depicted in FIG. 9, the heat spreader 14 and the heat insulator 15 are disposed in the opening 13x. A first through-hole 13y fluidly communicates with a first through-hole 11fy. A second through-hole 13y fluidly communicates with a second through-hole 11fy. A third through-hole 13y fluidly communicates with a third through-hole 11fy. A fourth through-hole 13y fluidly communicates with a fourth through-hole 11fy. In short, each of the through-holes 13y fluidly communicates with a corresponding one of the through-holes 11fy.

The holder 13 further includes a protruding portion 13z. As depicted in FIGS. 8 and 9, the protruding portion 13z protrudes from a peripheral surface of the holder 13 defining the opening 13x, into the opening 13x. As depicted in FIGS. 8 and 9, the heat insulator 15 holding the heat spreader 14 is supported on the protruding portion 13z.

As depicted in FIG. 4, the support plate 16 is frame-shaped, and fixed at an upper surface of the holder 13. A lower surface of the support plate 16 contacts the upper surface of the holder 13. The support plate 16 has one opening 16x and four through-holes 16y. The opening 16x and the four through-holes 16y extend through the support plate 16 in its thickness direction. The heat spreader 14 is exposed to an exterior of the head module 10m, via the opening 16x. A first through-hole 16y fluidly communicates with the first through-holes 13y. A second through-hole 16y fluidly communicates with the second through-hole 13y. A third through-hole 16y fluidly communicates with the third through-hole 13y. A fourth through-hole 16y fluidly communicates with the fourth through-hole 13y. In short, each of the through-holes 16y fluidly communicates with a corresponding one of the through-holes 13y. Each of the through-holes 16y has a diameter smaller than a corresponding one of the through-holes 13y.

A lower end portion of a first pipe 17 engages in the first through-hole 13y and the first through-hole 16y. A lower end portion of a second pipe 17 engages in the second through-hole 13y and the second through-hole 16y. A lower end portion of a third pipe 17 engages in the third through-hole 13y and the third through-hole 16y. A lower end portion of a fourth pipe 17 engages in the fourth through-hole 13y and the fourth through-hole 16y. In short, the four pipes 17 are independent of one another. A lower end portion of each of the four pipes 17 engages in a corresponding one of the through-holes 13y of the holder 13 and a corresponding one of the through-holes 16y of the support plate 16. An upper end portion of each of the four pipes 17 protrudes upward relative to an upper surface of the support plate 16. The pipes 17 fluidly communicate with the ink tanks (not depicted) disposed in the printer 1, via tubes connected to the upper end portions of the pipes 17. Ink in the ink tanks is supplied, via the pipes 17, to the through-holes 11fy fluidly communicating with the pipes 17. The ink is then supplied to the common channels 11y communicating with the through-holes 11fy. To return ink in the four common channels 11y to the ink tanks, the ink may flow to the through-holes 11fy communicating with the common channels 11y. The ink may then be returned to the ink tanks, via the pipes 17 communicating with the through-holes 11fy.

As depicted in FIG. 4, the heat spreader 14 has a generally rectangular plate shape. The heat spreader 14 entirely overlaps the actuator 11n when viewed in the vertical direction. As depicted in FIGS. 8 and 9, a lower surface 14a of the heat spreader 14 is in contact with an upper surface of the driver ICs 12. The lower surface 14a serves as a thermal contact surface with the driver ICs 12.

The driver ICs 12 are located between the head 11 and the heat spreader 14. The driver ICs 12 are enclosed by the holder 13 in the horizontal direction and held between the head 11 and the heat spreader 14 in the vertical direction. In other words, the driver ICs 12 are covered by the holder 13, the head 11 and the heat spreader 14, as depicted in FIGS. 4, 8 and 9.

As depicted in FIG. 4, the heat insulator 15 includes a generally rectangular frame having two sets of opposed ends defining an open center portion. The frame extends around side peripheral surfaces 14b of the heat spreader 14. Each side peripheral surface 14b is perpendicular to the lower surface 14a. A bridge portion 15b extends across the open center portion between one set of the ends of the frame. A pair of tabs 15c are spaced apart from one another in a thickness direction of the heat insulator 15 (i.e. vertical direction) and extend from one end of the frame into the open center portion, with a connecting portion 15d extending vertically between the tabs 15c. An outer edge of the heat spreader 14 is received between the tabs 15c so as to be held therebetween. In other words, as depicted in FIG. 4, a recess is formed between the tabs 15c in an inner peripheral surface of one end of the frame 15a, and an outer edge of the heat spreader 14 is held between the tabs 15c.

A portion of the frame portion 15a defining a bottom of the recess corresponds to the connecting portion 15d. A portion of the frame portion 15a defining a pair of sides of the recess corresponds to the pair of tabs 15c. The pair of sides interposes the bottom of the recess therebetween in the vertical direction. In other words, one of the sides of the recess formed in the frame portion 15a is defined by one of the tabs 15c. The other one of the sides of the recess formed in the frame portion 15a is defined by the other one of the tabs 15c.

The outer edge of the heat spreader 14A engages in the recess defined by the pair of tabs 15c and the connecting portion 15d. More specifically, one of the tabs 15c contacts an end portion of an upper surface of the heat spreader 14. The other one of the tabs 15c contacts an end portion of a lower surface of the heat spreader 14. The connecting portion 15d defining the bottom of the recess of the frame portion 15a contacts the side peripheral surface 14b of the heat spreader 14. The side peripheral surface 14b connects an edge of the end portion of the upper surface of the heat spreader 14 and an edge of the end portion of the lower surface of the heat spreader 14a to each other. The connecting portion 15d is located between the side peripheral surface 14b and the holder 13.

The heat insulator 15 further includes a projection 15p. The projection 15p is disposed at and around an outer peripheral surface of the frame portion 15a. In other words, the projection 15p is provided at a particular portion of the connecting portion 15d or a particular side of the connecting portion 15d. The particular portion faces the holder 13, and the particular side is one of the two side surfaces of the connecting portion 15d opposite to the recess.

The heat insulator 15 is a single or one-piece member having the portions 15a-15d. In short, one heat insulator 15 is provided with the portions 15a-15d. The heat insulator 15 is made of elastic material, such as rubber (e.g., nitrile rubber (“NBR”), fluorine-based rubber, silicone-based rubber, ethylene-propylene-diene rubber (“EPDM”), and elastomer), and thus is able to self-restore to its original shape. The heat insulator 15 has higher elasticity than the heat spreader 14 and the holder 13. In shorter, the heat insulator 15 is more flexible than the heat spreader 14 and the holder 13.

A portion of the heat insulator 15 that overlaps or contacts other members or components in FIGS. 8 and 9 may be elastically deformed and compressed during the assembly of the head module 10m.

The head module 10m may be assembled as follows:

First, the heat insulator 15 holds the heat spreader 14. At this time, the outer edge of the heat spreader 14 engages in the recess defined by the pair of tabs 15c and the connecting portion 15d, and the lower surface 14a contacts an upper surface of the bridge portion 15b.

The heat insulator 15 holding the heat spreader 14 is positioned on the protruding portion 13z in the opening 13x of the holder 13. At this time, the projection 15p is pressed against the peripheral surface of the holder 13 defining the opening 13x and compressed.

Each of the pipes 17 is engaged in a respective one of the through-holes 13y of the holder 13. Subsequently, the head 11 is positioned at the lower surface of the holder 13, and the support plate 16 is positioned at the upper surface of the holder 13.

Subsequently, each of the screws 19 is screwed into the head 11, the holder 13 and the support plate 16. At this time, an upper portion of the heat insulator 15 is pressed against the lower surface of the support plate 16 and compressed. Assembly of the head module 10m thus completes.

The heat insulator 15 has a thermal conductivity lower than the heat spreader 14. More specifically, the thermal conductivity of the heat insulator 15 formed of, for example, silicone-based rubber, is approximately 0.16 [unit: W/(m·K)]. The thermal conductivity of the heat spreader 14 formed of, for example, aluminum, is approximately 236 [unit: W/(m·K)]. The thermal conductivity of the holder 13 formed of, for example, epoxy resin, is approximately 0.21 [unit: W/(m·K)].

As described above, the head module 10m includes the heat insulator 15 disposed between the heat spreader 14 and the holder 13 (refer to FIG. 9). The heat insulator 15 has a thermal conductivity lower than the heat spreader 14. This configuration may reduce thermal transfer between the heat spreader 14 and the holder 13, and may prevent deformation of the holder 13 due to the heat from the heat spreader 14.

The driver ICs 12 are covered by the holder 13, the head 11 and the heat spreader 14 (refer to FIGS. 4 and 9). This configuration may shield the driver ICs 12 with the holder 13, the head 11, and the heat spreader 14, and may prevent or reduce mist reaching the driver ICs 12.

The heat insulator 15 includes the pair of tabs 15c, configured to clamp the outer edge of the heat spreader 14 in its thickness direction (refer to FIGS. 4 and 9). This configuration may allow the heat spreader 14 to be held by the pair of tabs 15c.

The heat insulator 15 further includes the connecting portion 15d connecting the tabs 15c to each other and extending in the thickness direction of the heat spreader 14 (refer to FIGS. 4 and 9). This configuration may allow the heat spreader 14 to be held more securely by the pair of tabs 15c and the connecting portion 15d.

The heat insulator 15 is a single or one-piece member including the tabs 15c and the connecting portion 15d (refer to FIGS. 4 and 9). This configuration may allow the heat insulator 15 to be handled more readily than a heat insulator including the tabs 15c and the connecting portion 15d that are separate members. In addition, the heat spreader 14 may just be engaged in the recess defined by the pair of tabs 15c and the connecting portion 15d of the heat insulator 15 to assemble the heat spreader 14 and the heat insulator 15 together. In short, the head module 10m may be manufactured readily.

The heat insulator 15 includes the projection 15p disposed at a portion of the heat insulator 15 facing the holder 13. The projection 15p contacts the holder 13 and has elasticity (refer to FIGS. 4 and 9). Such a configuration that employs point contact between the holder 13 and the heat insulator 15 at the projection 15p, may ensure the sealability or effectiveness of seal between the holder 13 and the heat insulator 15 more reliably than a configuration that employs face contact between the holder 13 and the heat insulator 15.

The heat insulator 15 includes an intervening portion (e.g., the connecting portion 15d) located between the side peripheral surface 14b of the heat spreader 14 and the holder 13 (refer to FIG. 9). The projection 15p may be located at a portion of the intervening portion (e.g., the connecting portion 15d) facing the holder 13. In this configuration, the projection 15p may help to maintain the sealability or effectiveness of seal between the holder 13 and the heat insulator 15 when the heat spreader 14 is moved in a direction perpendicular to a thickness direction thereof, for example, due to the movement of the head module 10m during an image formation.

The heat insulator 15 is in contact with the heat spreader 14 and the holder 13 (refer to FIGS. 8 and 9). This configuration may prevent a gap or space from being created between the heat spreader 14 and the holder 13, leading to reduction in short-circuit failures in the driver ICs 12 due to the entry of mist.

The heat insulator 15 includes the frame portion 15a that surrounds the side peripheral surfaces 14b of the heat spreader 14 (refer to FIG. 4). In this configuration, the frame portion 15a enclosing the side peripheral surfaces 14b may reduce the holder 13 from being deformed by the heat from the heat spreader 14.

The heat insulator 15 has elasticity. In this configuration, elasticity of the heat insulator 15 may provide improved sealing between the heat spreader 14 and the holder 13. This may reliably reduce short-circuit failures in the driver ICs 12.

The heat insulator 15 includes the frame portion 15a that has elasticity and surrounds the side peripheral surfaces 14b of the heat spreader 14 (refer to FIG. 4). In this configuration, the frame portion 15a surrounding the side peripheral surfaces 14b of the heat spreader 14 may prevent the entry of mist, which may prevent short-circuit failures in the driver ICs 12 more reliably.

The heat insulator 15 further includes the bridge portion 15b connecting two opposing portions of the frame portion 15a (refer to FIG. 4). When the heat insulator 15 having elasticity supports the heat spreader 14, the heat insulator 15 may curl up, resulting in poor assembly. The configuration of the heat insulator 15 including the bridge portion 15b may reduce or prevent the heat insulator 15 from curling up, reducing poor assembly.

The heat insulator 15 is disposed between the heat spreader 14 and the support plate 16 (refer to FIGS. 8 and 9). This configuration may allow the heat insulator 15 to hold the heat spreader 14 securely in cooperation with the holder 13 and the support plate 16, as well as may prevent the support plate 16 from being deformed by the heat from the heat spreader 14.

While aspects are described in detail with reference to specific embodiments thereof, this is merely an example, and various changes, arrangements and modifications may be made therein without departing from the spirit and scope of the disclosure.

As long as the heat spreader is in thermal communication with the driver IC such that heat exchange occurs between the heat spreader and the driver IC, the heat spreader does not necessarily contact the driver IC directly but may contact the driver IC indirectly (e.g., via thermal grease).

A radiator (e.g., a member with a plurality of fins) may be disposed above a heat spreader. In this configuration, the radiator may be integral with the heat spreader and formed at an upper portion of the heat spreader. Alternatively, a radiator may be separate from a heat spreader and may be fixed to the heat spreader in contact with an upper surface of the heat spreader.

The heat spreader is not limited to being made of aluminum but may be made of another material having heat radiating effect (e.g., copper, alloy including copper, stainless steel, ceramic, and metal oxide including ceramic).

The heat spreader is not limited to being formed into a generally rectangular shape when viewed in the thickness direction of the heat spreader, but may be formed into another shape (e.g., a circular or elliptical shape).

The heat insulator is not limited to being made of rubber but may be made of material having elasticity (e.g., sponge) other than rubber.

As long as the projection has elasticity, the whole heat insulator does not necessarily have elasticity.

The heat insulator does not necessarily have elasticity.

The pair of tabs and the connecting portion of the heat insulator may be separate members.

The heat insulator does not necessarily include a pair of tabs. In other words, the heat insulator may only have a portion intervening between an end face of the heat spreader and the holder (e.g., the connecting portion or the intervening portion).

As long as the projection is disposed at a portion of the heat insulator facing the holder, the projection is not necessarily disposed at a side surface of the heat insulator. For example, the projection may be disposed at a lower surface of the heat insulator.

The projection may be omitted. In other words, contact between the holder and the heat insulator is not limited to point contact at the projection but may be face contact.

The heat insulator does not necessarily contact the heat spreader and the holder, but may face at least one of the heat spreader and the holder via a space.

The frame portion is not limited to being formed into a rectangular shape but may be formed into another shape (e.g., a circular or elliptical shape) corresponding to an outer edge of a heat spreader.

The holder, the heat insulator, and the supporting member are not limited to being formed in a frame shape, but may be formed in another shape.

The holder is not limited to being made of epoxy resin, but may be made of another material (e.g., metal or ceramic).

The supporting member is not limited to being made of stainless steel (e.g., SUS430), but may be made of another material (e.g., metal other than stainless steel, or ceramic). The supporting member may be omitted.

The number of the driver ICs is not limited to two, but may be one, or three or more. The driver IC may not necessarily be covered by the holder, the head and the heat spreader.

The actuator is not limited to a piezoelectric type that employs piezoelectric elements, but may be a thermal type that employs heating elements, or an electrostatic type that employs electrostatic force.

The head module of the disclosure is not limited to a line type, but may be a serial type.

The disclosure may be applied to various liquid ejection apparatuses including, but not limited to printers. The disclosure may also be applied to, for example, facsimile machines, copiers, and multi-functional devices.

Objects or media to which liquid is ejected are not limited to sheets but may be textiles, wood, and labels.

Liquid to be ejected from the orifices is not limited to ink, but may be another type of liquid (e.g., treatment liquid for agglutinating or precipitating ingredients in ink).

Claims

1. A head module, comprising: a head including: a flow channel substrate having an orifice and a flow channel in fluid communication with the orifice; andan actuator adjacent the flow channel;a driver IC that is electrically connected to the actuator;a heat spreader in thermal contact with the driver IC to facilitate heat exchange between the heat spreader and the driver IC, wherein the driver IC is located between the head and the heat spreader;a holder that supports the head; anda heat insulator located between the heat spreader and the holder, the heat insulator having a thermal conductivity lower than the heat spreader.

2. The head module of claim 1, wherein the driver IC is surrounded by the holder, the head, and the heat spreader.

3. The head module of claim 1, wherein the heat insulator includes a pair of tabs including first and second tabs spaced apart in a thickness direction of the heat insulator and projecting from an inner surface of one end of the heat insulator, wherein an outer edge of the heat spreader is received between the first and the second tabs.

4. The head module of claim 3, wherein the heat insulator further includes a connecting portion that extends in the thickness direction and connects the first and second tabs to each other.

5. The head module of claim 4, wherein the heat insulator is a single member, wherein first and second tabs and the connecting portion are integrally formed portions of the single member.

6. The head module of claim 1, wherein the heat insulator includes a projection extending from an outer surface of the heat insulator towards the holder to contact the holder, and wherein the contact of the projection against the holder elastically deforms the projection.

7. The head module of claim 6, wherein the heat insulator includes an intervening portion located opposite an end face of the heat spreader in a horizontal direction perpendicular to the thickness direction of the heat insulator, the end face extending in the thickness direction of the heat spreader, the heat spreader having a thermal contact surface in thermal communication with the driver IC, the thermal contact surface extending perpendicularly to the end surface of the end face of the heat spreader; and wherein the projection is located at a portion of the intervening portion facing the holder.

8. The head module of claim 1, wherein the heat insulator is in contact with the heat spreader and the holder.

9. The head module of claim 8, wherein the heat insulator comprises an elastic material.

10. The head module of claim 9, wherein the heat insulator includes a frame portion that surrounds a side peripheral surface of the heat spreader.

11. The head module of claim 10, wherein the heat insulator further includes a bridge portion disposed in an area enclosed by the frame portion and connecting two opposing portions of the frame portion.

12. The head module of claim 1, wherein the heat insulator includes a frame portion that surrounds a side peripheral surface of the heat spreader.

13. The head module of claim 1, further including a support plate fastened to the head; wherein the heat insulator is located between the heat spreader and the support plate such that an upper surface of the heat insulator contacts a lower surface of the support plate.

14. A liquid ejection apparatus, comprising: the head module of claim 13; anda frame that supports the support plate.

15. A head module, comprising: a driver IC;a head configured to eject liquid in response to the driver IC;a holder supporting the head;a heat spreader in thermal communication with the driver IC, the heat spreader including a peripheral side surface;a support plate opposite the head such that the holder is between the support plate and the head; anda heat insulator receiving the heat spreader so as to surround the peripheral side surface of the heat spreader to thermally isolate the holder and the support plate from the heat spreader.

16. The head module of claim 15, wherein the holder receives the heat insulator so as to surround a side surface of the heat insulator extending around an outer periphery of the heat spreader.

17. The head module of claim 15, wherein the heat insulator receives the heat spreader such than the heat spreader does not directly contact the holder.

18. The head module of claim 15, wherein the heat insulator receives the heat spreader such that the heat spreader does not directly contact the support plate.

19. The head module of claim 15, further comprising a plurality of fasteners connecting the support plate to the head such that the heat insulator and the holder are sandwiched between the support plate and the head.

20. The head module of claim 19, wherein the fasteners extend through openings in the holder.

21. The head module of claim 19, wherein the fasteners comprise screws, and wherein the head defines screw holes receiving the screws.

22. The head module of claim 15, wherein the heat insulator includes an inner surface defining an opening and surrounding at least a portion of the side of the heat spreader, wherein the heat spreader is within the opening of the heat insulator, andwherein the inner surface of the heat insulator receives at least the portion of the side surface of the heat spreader.

23. The head module of claim 15, wherein the heat insulator has a thermal conductivity lower than the heat spreader.

24. The head module of claim 15, wherein the holder defines an opening with a protruding portion extending into the opening, and wherein the heat insulator is supported on the protruding portion.

25. The head module of claim 15, wherein the heat insulator includes a projection extending from an outer peripheral surface of the heat insulator, and wherein the projection contacts an inner side surface of the holder.

26. The head module of claim 25, wherein the inner side surface of the holder elastically deforms the projection.

27. The head module of claim 15, further including a support plate fastened to the head; wherein the heat insulator is located between the heat spreader and the support plate such that an upper surface of the heat insulator contacts a lower surface of the support plate.

28. A liquid ejection apparatus, comprising: the head module of claim 27; anda frame that supports the support plate.

29. A method of assembling a head module, comprising; providing a head including: a flow channel substrate having an orifice and a flow channel communicating with the orifice; andan actuator adjacent the flow channel;thermally attaching a heat spreader to a driver IC that is electrically connected to the actuator;attaching the head to a holder; andthermally insulating the heat spreader from the holder, including situating the heat spreader in a heat insulator such that the heat insulator surrounds peripheral side surfaces of the heat spreader.

30. The method of claim 29, further comprising; situating the heat insulator in a central opening of the holder.

31. The method of claim 30, wherein situating the heat spreader in the heat insulator includes situating the heat spreader in a central opening of the heat insulator.

32. The method of claim 31, wherein situating the heat spreader in the central opening of the heat insulator includes inserting an end of the heat spreader in a recess formed in an inside surface of the heat spreader.

33. The method of claim 29, wherein thermally insulating the heat spreader from the holder includes arranging the heat spreader such that the heat spreader does not directly contact the holder.

34. The method of claim 29, further comprising providing a support plate, wherein attaching the head to the holder includes situating the holder between the support plate and the head, and attaching the support plate to the head.

35. The method of claim 34, further comprising thermally insulating the heat spreader from the support plate.

36. The method of claim 35, wherein thermally insulating the heat spreader from the support plate includes arranging the heat spreader such that the heat spreader does not directly contact the support plate.