Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-07-28
2001-03-13
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06199972
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid discharging head having a movable member displaceable by the utilization of the creation of a bubble occurring by heat energy being caused to act on liquid, a head cartridge, a liquid discharging apparatus and a liquid discharging method using the liquid discharging head.
Particularly, the present invention relates to a liquid discharging head for controlling the discharge state of liquid by a movable member displaceable by pressure resulting from the disappearance of a bubble, a head cartridge, a liquid discharging apparatus and a liquid discharging method using the liquid discharging head.
2. Related Background Art
As a method of steeply varying the pressure in a liquid flow path having a discharge port for discharging liquid therethrough to thereby discharge the liquid in the liquid flow path through the discharge port, there is known a bubble jet recording method of giving energy such as heat to liquid to thereby cause a state change accompanied by a steep volume change (the creation of a bubble) in the liquid, and discharging the liquid from a discharge port by an action force based on this state change, and causing the liquid to adhere to a recording medium to thereby effect image formation. In a recording apparatus using this bubble jet recording method, as disclosed in U.S. Pat. No. 4,723,129, etc., there are generally disposed a discharge port for discharging liquid, a liquid flow path communicating with this discharge port, and an electrothermal converting member as energy generating means for discharging liquid disposed in the liquid flow path.
According to such a liquid discharging method, images of high dignity can be recorded at a high speed and with low noise, and in a head carrying out this liquid discharging method, discharge ports for discharging the liquid can be disposed highly densely, and this leads to many excellent advantages that recorded images of high resolution and further, colored images can be easily obtained by a compact apparatus. Therefore, in recent years, this bubble jet recording method has been utilized in many office machines such as printers, copying apparatuses and facsimile apparatuses, and has further come to be utilized even in an industrial system such as a textile printing apparatus.
Also, in such a liquid discharging method, the condition for driving the electrothermal converting member is a simple rectangular pulse, and this leads to the feature that there is obtained a very stable discharging state.
On the other hand, as another liquid discharging method, there is known a piezo system whereby electricity is applied to a piezoelectric element and the deformation thereof is utilized to discharge liquid from a discharge port.
In such a liquid discharging method, the volume of a nozzle storing liquid therein can be changed to both an increase side and a decrease side and therefore, depending on the driving condition of the piezoelectric element, it is possible to change the discharge state of the liquid.
Now, in recent years, gradation recording in which the discharge amount is variably controlled has been effected with a view to improve the quality of image. However, if an attempt is made to variably control the discharge amount in the prior-art liquid discharging method as described above, the driving condition and circuit become complicated and the mechanical reaction after the operation of the piezoelectric element necessarily occurs, and this adversely affects the discharge. Therefore, in such a liquid discharging method, control for repeating a stable discharge state must be effected, and this leads to the problem that the control method becomes complicated.
Particularly, the influence of this reaction is great in an operation which is not accompanied by discharge and therefore, it is practically impossible to effect the control as described above. Further, in the piezoelectric element itself, the structure thereof is complicated and the amount of displacement thereof is small and therefore, to discharge the liquid, it is necessary to make the area of the piezoelectric element relative to the liquid flow path large, and this is impossible to realize in a system wherein parts are disposed highly densely as in the bubble jet system.
SUMMARY OF THE INVENTION
The present invention intends to realize a highly dense arrangement which could not be provided from the above-described prior-art liquid discharging method and yet achieve the control of the discharge state by a very simple circuit and driving method, and the main objects thereof are as follows.
A first object of the present invention is to provide a liquid discharging head and method which can realize a highly dense nozzle arrangement and yet can achieve the stabilization of the discharge state.
A second object of the present invention is to provide a liquid discharging head and method which can realize a highly dense nozzle arrangement and yet can variably control the discharge amount.
A third object of the present invention is to provide a liquid discharging head and method which can realize a highly dense nozzle arrangement and yet make the multistage harmony of the discharge amount possible.
To achieve the above objects, the present invention is a liquid discharging method of discharging liquid from a discharge port for discharging liquid by a liquid discharging element in a first liquid flow path communicating with the discharge port and supplying the liquid to the discharge port, characterized by the use of a variable member for causing negative pressure to act on the first liquid flow path.
Also, it is characterized in that provision is made of a movable member displaceable relative to the first liquid flow path only by the disappearance of a bubble, and the negative pressure is caused to act by the displacement of the movable member.
Also, it is characterized in that the movable member is displaced away from the first liquid flow path by the disappearance of the bubble.
Also, it is characterized in that the movable member is a movable valve having a free end at the discharge port side.
Also, it is characterized in that the movable member is movable film constituting a part of the flow path wall of the first liquid flow path.
Also, it is characterized in that the movable member is displaced at predetermined timing.
Also, it is characterized in that the movable member is displaced in a state in which the liquid is discharged from the discharge port.
Also, it is characterized in that the movable member is displaced on the basis of the displacement of the meniscus of the liquid in the discharge port.
Also, it is characterized in that detecting means for detecting the presence or absence of the liquid is provided near the discharge port, and the detection result in a state in which the movable member is not displaced and the detection result in a state in which the movable member is displaced are compared with each other to thereby detect the state of the liquid.
Also, the present invention is a liquid discharging head having:
a discharge port for discharging liquid therefrom;
a first bubble creating area for creating a first bubble in the liquid; and
a first liquid flow path provided with the first bubble creating area and communicating with the discharge port;
the liquid discharging head discharging the liquid in the first liquid flow path from the discharge port by the creation of the first bubble,
characterized by:
a second bubble creating area for creating a second bubble in the liquid;
a second liquid flow path provided with the second bubble creating area; and
negative pressure acting means provided between the first liquid flow path and the second liquid flow path and using a variable member for causing only negative pressure to act in the first liquid flow path by the disappearance of the second bubble.
Also, it is characterized in that the negative pressure acting means is displaced away from the first liquid flow path by the disappearance of the second bubble.
Also, it is
Ishinaga Hiroyuki
Kashino Toshio
Sugiyama Hiroyuki
Taneya Yoichi
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Stephens Juanita
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