The present invention relates to a recording head that discharges liquids such as ink (hereunder, referred to collectively as “ink”) in accordance with input electrical signals.
As one kind of ink jet recording head, a recording head is known that discharges ink droplets utilizing energy generated by an electrothermal converting element. In this kind of recording head, as shown in
The electrothermal converting element 203 generates a phase change in the ink inside the liquid chamber 201 by imparting thermal energy to the ink, thereby causing minute ink droplets to be discharged from the discharge port 200 by the pressure of air bubbles generated in the ink at that time. Surplus heat is transmitted to the supporting member 205 through the liquid discharge substrate 204 and dissipated.
In this type of ink jet recording head, because ink droplets are discharged utilizing the pressure of air bubbles generated when ink develops into foams, when the temperature of the liquid discharge substrate becomes high the discharge control becomes difficult, resulting in disadvantages such as the erroneous discharge of ink droplets. Therefore, conventional ink jet recording apparatuses are equipped with a mechanism that temporarily suspends discharge operations when the temperature of the liquid discharge substrate has become high. Meanwhile, there is an ever-growing trend towards densification of electrothermal converting elements in order to respond to demands for high-speed recording at higher resolutions, and the electrical power consumption of electrothermal converting elements is also continuing to increase. As a result, the temperatures of liquid discharge substrates during operation are tending to increase, and if this trend continues it is anticipated that the recording heads will frequently fall into a suspended state during operation.
An object of this invention takes into consideration the circumstances described above, and is directed at efficiently releasing the heat of a liquid discharge substrate to effectively suppress increases in the substrate temperature.
Another object of this invention is to provide an ink jet recording head having a supporting member comprising a liquid supply hole; and a liquid discharge substrate comprising a liquid supply port that communicates with the liquid supply hole, a discharge port from which liquid that was supplied from the liquid supply port is discharged, and a discharge energy generation means that generates energy for discharging the liquid from the discharge port; wherein, the liquid discharge substrate is mounted on a supporting member through a heat dissipation member, and the area of the heat dissipation member is larger than the projected area of the liquid discharge substrate that faces the supporting member. A further object of this invention is to provide an ink jet recording apparatus that uses this ink jet recording head.
The embodiments of this invention described hereunder are apparatuses that efficiently dissipate heat generated from a liquid discharge substrate by disposing between a supporting member and a liquid discharge substrate a foil-shaped heat dissipation member having an area that is larger than the projected area of the liquid discharge substrate with respect to the supporting member. More specifically, one side of the liquid discharge substrate mounted on top of the supporting member faces the external surface of the supporting member. Thus, the invention is directed at increasing the heat dissipating efficiency of the apparatus by diffusing over a wide area heat generated from the liquid discharge substrate, by disposing between the external surface of the supporting member and the external surface (opposing surface) of the liquid discharge substrate with respect to the external surface of the supporting member a heat dissipation member having an area that is larger than the opposing surface. In this connection, when the aforementioned foil-shaped heat dissipation member with an area larger than the opposing surface is disposed between the supporting member and the liquid discharge substrate, normally the entire circumference of the heat dissipation member extends to outside of the liquid discharge substrate. However, depending on the relative location or aspect ratio of the heat dissipation member with respect to the liquid discharge substrate, there are also cases where one part of the circumference of the heat dissipation member is concealed below the liquid discharge substrate. Naturally, even if one part of the circumference of the heat dissipation member is concealed below the liquid discharge substrate, the objects of this invention are achieved as long as the area of the heat dissipation member satisfies the above condition. Likewise, even in a case where a notch or a slit is formed in one part of the heat dissipation member, the objects of this invention are achieved as long as the area of the heat dissipation member satisfies the above condition. Further, even when two or more heat dissipation members are provided or a heat dissipation member is separated into two or more parts and heat conduction is possible between the two or more heat dissipation members, the objects of the invention are achieved as long as the apparatus is one in which the total area of these heat dissipation members satisfies the aforementioned condition. Furthermore, although copper foil is exemplified as a heat dissipation member in each of the following embodiments, the heat dissipation member is not limited to a foil-shaped member and it may be a sheet-shaped member with a thickness that is greater than a member that is generally referred to as foil. In addition, the material for the heat dissipation member may be material at least having thermal conductivity more excellent than the adhesive and the supporting member used therein. Moreover, the material for the heat dissipation member may be material having thermal conductivity more excellent than the liquid discharge substrate.
By contacting the aforementioned liquid discharge substrate and heat dissipation member through a bump, the heat conduction efficiency from the liquid discharge substrate to the heat dissipation member can be increased and the heat dissipating characteristics can also be enhanced. In addition, by providing a metal film on the liquid discharge substrate and contacting the metal film and the heat dissipation member through a bump, the heat conduction efficiency can be increased even more.
Hereunder, an example of one embodiment of the recording head of this invention is described referring to FIGS. 1 to 3.
As shown in
The supporting member 1 is made from alumina and, as shown in
The area of the copper foil 31 is larger than the projected area of the liquid discharge substrate 2 with respect to the top surface 21 of the supporting member 1, and as illustrated most clearly in
According to the recording head of this example having the above structure, heat of the liquid discharge substrate 2 is conducted to the copper foil 31 and diffused throughout the entire copper foil 31 to dissipate, and also conducted to the supporting member 1 to dissipate. More specifically, because heat of the liquid discharge substrate 2 is diffused by the copper foil 31 that has an area larger than the underside 11 of the substrate 2, heat dissipating characteristics are realized that are superior to those of a structure in which the underside 11 of the liquid discharge substrate 2 is bonded directly to the top surface 21 of the supporting member 1. Furthermore, with respect to the operational effects, it will be understood that the material of the heat dissipation member is not limited to copper, and any material may be used as long as it is a material with better heat conductivity than at least the bonding agents 40, 41 and the supporting member 1. Moreover, it is preferable that the heat dissipation member is a material with better heat conductivity than the liquid discharge substrate 2. In addition, similarly, the material for the supporting member 1 is not limited to alumina and the material for the liquid discharge substrate 2 is not limited to silicon. This is also applicable to the embodiments described hereinafter.
The bonding agent 41 that bonds the underside 11 of the liquid discharge substrate 2 and the top surface 32 of the copper foil 31 has thermal resistance that inhibits heat conduction from the liquid discharge substrate 2 to the copper foil 31. Further, the bonding agent 40 that bonds the underside 30 of the copper foil 31 and the top surface 21 of the supporting member 1 has thermal resistance that inhibits heat conduction from the copper foil 31 to the supporting member 1. Accordingly, it is preferable from the viewpoint of enhancing the heat dissipation characteristics to decrease as much as possible the aforementioned thermal resistance by reducing the thickness of the bonding agents 40 and 41 or using a bonding agent with favorable heat dissipation characteristics. For example, the thickness of the bonding agent 40 is preferably 10 μm or less.
Hereunder, another example of an embodiment of the recording head of this invention is described referring to
The difference between the recording head of this example and the recording head of Embodiment 1 is the structure of the bond between the liquid discharge substrate 2 and the copper foil 31. More specifically, a metallic thin film 50 is formed on the underside 11 of the liquid discharge substrate 2, and the thin film 50 and the top surface 32 of the copper foil 31 are bonded through a plurality of heat-dissipating bumps 51. As illustrated most clearly in
According to the recording head of this example having the above structure, the heat conduction efficiency from the liquid discharge substrate 2 to the copper foil 31 is increased and more favorable heat dissipation characteristics are obtained. In this connection, with regard to the aforementioned operational effects of the thin film 50 and the heat-dissipating bumps 51, the materials of the thin film 50 and the heat-dissipating bumps 51 are not limited to specific materials, and it will be understood that any materials may be used as long as they are materials that have better heat conductivity than the bonding agents 40 and 41. For example, although in this example the material of the thin film 50 is aluminum, the thin film 50 may be formed by gold. Further, although in this example the heat-dissipating bumps 51 are solder bumps, they can be substituted with gold bumps. Furthermore, although according to this example the thin film 50 is formed only on one part (circumference of the liquid supply port 12) of the underside 11 of the liquid discharge substrate 2, it is possible to further enhance the heat dissipation characteristics by expanding the area of the thin film 50 or increasing the number of the heat-dissipating bumps 51.
Hereunder, a further example of an embodiment of the recording head of this invention is described. The basic structure of the recording head of this example is the same as that of the recording head of Embodiment 1. The difference between the recording head of this embodiment and the recording head of Embodiment 1 is that the copper foil as a heat dissipation member is formed on a film-shaped electric circuit board (hereunder, referred to as “flexible printed circuit”) on which wiring patterns for supplying driving signals or the like to electrothermal converting elements were formed. Therefore, after giving a general description of the structure of the flexible printed circuit comprising the recording head of this example referring to
A flexible printed circuit 62 shown in
Next, the structure of the recording head of this example will be described referring to
It is also possible to form a metallic thin film on the underside 11 of the liquid discharge substrate 2 and bond the thin film with the copper foil 60 through the heat-dissipating bumps. That is, the bonding structure described Embodiment 2 can also be employed for the recording head of this example. Further, when providing electrodes (underside electrodes) on the underside of the liquid discharge substrate 2 and bringing the underside electrodes into conduction with the surface electrodes 69 through electrodes that penetrate the substrate 2 (penetrating electrodes), the aforementioned metallic thin film can be utilized as an underside electrode. For example, it is possible to utilize the aforementioned metallic thin film as an underside electrode by connecting the metallic thin film and the penetrating electrodes through bumps. At that time, the aforementioned heat-dissipating bumps may be used as the bumps that bring the metallic thin film into conduction with the penetrating electrodes, or bumps for electrical connection may be used that are provided separately to the heat-dissipating bumps.
Furthermore, as shown in
Hereunder, a further embodiment of the recording head of this invention is described. The recording head of this example is the same as the recording head of Embodiment 3 in the respect that a liquid discharge substrate is mounted on a supporting member via a flexible printed circuit on which a copper foil was formed as a heat dissipation member. The difference between the recording head of this example and that of Embodiment 3 is that a plurality of liquid discharge substrates is mounted on a single flexible printed circuit. Thus, after giving a general description of the structure of the flexible printed circuit comprising the recording head of this example referring to
A flexible printed circuit 80 shown in
Next, the structure of the recording head of this example is described referring to
In the recording head of this example having the above structure, the heat of the liquid discharge substrate 2 is conducted to the copper foil 83a through the thin film 88 and the heat-dissipating bumps 87 and diffused and dissipated, and is also conducted to the copper foil 83b for diffusion and dissipation. Further, heat that is conducted to the copper foil 83b is also conducted to the supporting member 1 and dissipated.
Next, a recording apparatus (ink jet recording apparatus) that is capable of mounting the type of recording head described above is described as the fifth embodiment of this invention.
In the recording apparatus shown in
The carriage 102 is supported in a guided condition by guide shafts 103 that are provided in the main body of the apparatus extending in the main scanning direction. The carriage 102 is capable of moving back and forth along the guide shafts 103.
The carriage 102 is driven by a main scanning motor 104 through a driving mechanism comprising a motorized pulley 105, a driven pulley 106 and a timing belt 107 and the like, and the position and movement of the carriage 102 is also controlled thereby. The carriage 102 is also equipped with a home position sensor 130. Thus, the apparatus can know the position when the home position sensor 130 on the carriage 102 has passed the location of a shield 136.
At the carriage position at which the home position sensor 130 detects the shield 136 (home position) is disposed a cap 137 that seals the face on which the discharge port of the recording head H1001 is formed. The cap 137 is used to execute an ink vacuum recovery operation for the recording head through an opening within the cap by vacuum means (not shown). The cap 137 can move by means of a driving force transmitted through a gear or the like, and is capable of covering the face that forms the discharge port. A cleaning blade 138 is provided in the vicinity of the cap 137. The apparatus is configured so that the respective operations of capping, cleaning and vacuum recovery are performed with respect to the face that forms the ink discharge port of the recording head when the carriage 102 has moved to the home position.
A recording medium 108 such as a recording paper or a plastic thin sheet is supplied from an auto sheet feeder (hereafter, referred to as “ASF”) 132 by a pickup roller 131 that is driven in a rotational manner by a sheet feeding motor 135 after being separated into single sheets. The supplied recording medium 108 is transported (fed) through a position (print part) that faces the discharge port forming face of the recording head H1001 by a transport roller 109 rotated by the driving force of an LF motor 124 which is conveyed through a gear. At that time, determination as to whether or not the sheet was supplied and verification of the start position at the time of sheet feeding is performed when the recording medium 108 passes a paper end sensor 133. The paper end sensor 133 is also used for determining the actual location of the trailing end of the recording medium 108 and for ultimately determining the current recording position based on the actual trailing end.
In this connection, the underside of the recording medium 8 is supported by a platen (not shown) so that a flat printing surface is formed at the print part. In this case, the recording head H1001 mounted on the carriage 102 is supported so that the face that forms the discharge port thereof protrudes downwards from the carriage 102 to be parallel with the recording medium 108 between the above-described pair of transport rollers.
The recording head H1001 is mounted on the carriage 102 such that the direction of alignment of the discharge ports in each of the discharge port rows is a direction that intersects the above-described scanning direction of the carriage 102, to thus execute recording by discharging ink from the discharge port rows.
According to the ink jet recording head of each of the embodiments described in detail in the foregoing, since a foil-shaped heat dissipation member having an area larger than the projected area of a liquid discharge substrate with respect to a supporting member is disposed between the supporting member and the liquid discharge substrate, heat of the liquid discharge substrate is dissipated with a high degree of efficiency through the heat dissipation member and an increase in the substrate temperature is effectively suppressed.
This application claims priority from Japanese Patent Application No. 2004-214238 filed Jul. 22, 2004, which is hereby incorporated by reference herein.
Number | Date | Country | Kind |
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2004-214238 | Jul 2004 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP05/13523 | 7/15/2005 | WO | 11/22/2006 |