Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-06
2002-10-08
Hallacher, Craig (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S094000
Reexamination Certificate
active
06460978
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head for performing such operation as to record or print characters, symbols, images, or the like, among some others, on a recording medium that includes paper, plastic sheet, cloths, commodity, or the like by discharging a functionating liquid, such as ink, to enable it to adhere thereto. for example. The invention also relates to a method of manufacture therefor, and a liquid discharge apparatus.
2. Related Background Art
As a liquid discharge head (ink jet recording head), there is the one that records images by bubbling ink to be discharged by utilization of thermal energy generated by heat generating members, for example.
Conventionally, as an ink jet recording head such as this, there is the ink jet recording head as shown in
FIG. 9
, for example, which is structured by mounting a ceiling plate
102
, which is provided with an ink inlet port
103
, a common liquid chamber
104
, liquid flow paths
105
, and discharge ports
107
, on a base plate
101
having heat generating members
108
for bubbling use installed thereon for discharging ink.
For an ink jet recording head of the kind, various recording performances, such as image quality, resolution, and speed, among some others, are demanded to be higher still from now on. To materialize such higher recording performances, there is a need for structuring an ink jet recording head capable of discharging small ink liquid droplets with many numbers of discharge ports
107
.
For the ink jet recording head of the kind, a method is adopted to simply make the area of a bubbling heat generating member smaller as the method to make a discharging ink droplet small in order to enhance the resolution. However, if the area of the heat generating member is made smaller, a desired bubbling cannot be obtained, because among the thermal energy generated by the heat generating member, the ratio of energy that may contribute to bubbling is caused to be gradually reduced. In order to generate a sufficient bubbling energy, it is necessary to set the area of heat generating member at a slightly larger value. If the area of the heat generating member is made larger, the dissipation of energy is increased inevitably. Also, if the area of the heat generating member is made smaller, a bubble itself becomes smaller to result in the reduced efficiency of bubble that should contribute to discharging. Also, if the arrangement density of nozzles is made higher in order to make a higher recording possible, the number of heat generating members should increase, while there is the incapability that the area of the heat generating member is made very small as described earlier. A problem is then encountered that the energy dissipation becomes greater.
In contrast, as the ink jet recording head capable of enhancing the energy efficiency by conducting the pressure exerted by bubbling to each discharge port efficiently, an ink jet recording head is disclosed in the specification of European Laid-Open Patent 0436047, which is provided with various kinds of valve mechanisms between the common liquid chamber and the heat generating member in the liquid flow path in order to cut off the liquid flow path when pressure is exerted by driving the heat generating member, and to permit the liquid flow at the time of refilling that necessitates the generation of ink flow from the common liquid chamber to each heat generating member after liquid has been discharged. This ink jet recording head is structured for the purpose of enhancing the energy efficiency by suppressing the escape of the pressure exerted by driving the heat generating member to the common liquid chamber side which is opposite to the discharge port, and conduct the pressure thus exerted to the discharge port side efficiently.
Also, as the ink jet recording head that discharges ink liquid droplets by enabling the pressure exerted by piezoelement to act on ink by utilization of the piezoelement which serves as an electromechanical converting member, there has been disclosed in the specification of U.S. Pat. No. 4,514,742, the ink jet recording head which is provided with various kinds of valve mechanisms between the ink replenishing path, through which ink is replenished to a pressure chamber, and the pressure chamber, which is provided with piezoelement for exerting pressure whereby to discharge ink, in order to cut off the liquid flow path when pressure is exerted by driving the piezoelement, and to permit the liquid flow at the time of refilling that necessitates the generation of ink flow from the ink supply path to the pressure chamber.
SUMMARY OF THE INVENTION
However, the valve mechanisms disclosed in the specification of European Laid-Open Patent 0436047 use a valve member the height of which is the same as that of the liquid flow path as the valve member that closes the liquid flow path, which moves in the condition where the valve member is in contact with the upper and lower faces of the flow path. As a result, when the valve member moves, friction occurs between the upper and lower faces of the flow path and the valve member to make it difficult to enable the valve member to move smoothly, hence making this arrangement impracticable.
Also, in the same specification, there is disclosed the structure in which a valve mechanism is arranged between the heat generating element and discharge port in addition to the one between the common liquid chamber and heat generating member. However, since this valve mechanism is structured so that the liquid flow path is closed in a steady state, the liquid flow is not allowed to occur unless a force is exerted to move the valve member. Therefore, although it is possible to refill liquid by moving the valve member by means of the difference between pressures exerted across the valve mechanism for the portion of the heat generating member where the pressure is reduced due to debubbling, there is a fear that liquid cannot be refilled sufficiently on the discharge port portion, because only the surface tension of liquid is the force usable for refilling liquid to the discharge port portion, which is not strong enough to serve the purpose.
Also, in the specification of U.S. Pat. No. 4,514,742 referred to earlier, the disclosed structure is such that the valve mechanism is formed by a valve seat configured as if to make a part of the liquid flow path narrower, and an elastically formed plate type valve member that cuts off the liquid flow path by being in close contact with the valve seat in a steady state where no ink flow occurs. This valve member is displaced by liquid flow when refilling so as to permit the liquid flow, but being biased to the valve seat side to cut off the liquid flow path in the steady state, the valve member needs a force to a certain extent to be deformed when refilling. As a result, there is a fear that the replenishing characteristic of liquid is deteriorated, because the valve is allowed to cut off the liquid flow path again before refilling has been carried out sufficiently.
Also, in the same specification, the disclose valve mechanism is such that the valve member is structured so as to form a hole on the center thereof to release the central part of the liquid flow path in the steady state. With this structure, however, the pressure exerted by driving the heat generating member is allowed to escape to the common liquid chamber side during the period until the deformed valve member is closely in contact with the valve seat, thus inevitably making the effect smaller in enhancing the energy efficiency.
Further, in the same specification, the disclosed structure is such that another passage is arranged to detour around the liquid flow path provided for the valve mechanism, but with the structure thus arranged, the pressure exerted by driving the heat generating member is partly allowed to escape through this passage, thus making the effect smaller in enhancing the energy efficiency. Also, the difference of pressures across the val
Hallacher Craig
Stephens Juanita
LandOfFree
Liquid discharge head having narrowed portion of liquid flow... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid discharge head having narrowed portion of liquid flow..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid discharge head having narrowed portion of liquid flow... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2966163