Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-09-04
2003-03-04
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S062000, C347S065000
Reexamination Certificate
active
06527367
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head and an ink jet recording apparatus provided with such recording head. More particularly, the invention relates to the structure of the element base plate (heater board) of an ink jet recording head.
2. Related Background Art
In recent years, many recording apparatuses have been used, and for these recording apparatuses, the higher recording speed, the higher resolution, the higher quality, and the lower amount of noises are demanded, among some others. Here, an ink jet recording apparatus can be cited as the recording apparatus that meets these demands.
For the typical structure and operational principle of the method used therefor, it is preferable to adopt those implemental by the application of the fundamental principle disclosed in the specifications of U.S. Pat. Nos. 4,723,129 and 4,740,796, for example. This method is applicable to the so-called on-demand type recording and a continuous type recording as well. Here, in particular, with the application of at least one driving signal that corresponds to recording information, the on-demand type provides an abrupt temperature rise beyond nuclear boiling by each of the heaters arranged corresponding to a sheet or a liquid path where ink is retained. Then, the heat generating resistive member is caused to generate thermal energy, hence creating film boiling on the thermal activation surface of a recording head to effectively form resultant bubbles in ink one to one corresponding to each driving signal. Then, by the growth and shrinkage of each bubble, liquid is discharged through each of the discharge openings, hence forming at least one droplet. The driving signal is more preferably in the form of pulses because the growth and shrinkage of each bubble can be made instantaneously and appropriately so as to attain the performance of excellent discharges of liquid, in particular, in terms of the response action thereof.
For the ink jet recording head of the kind, thermal energy is given to ink in each nozzle to create bubbles, and by means of bubbling power, ink is discharged for recording. Therefore, it is extremely important to provide the stabilization of ink discharges for the fulfillment of the aforesaid demands, and also, to control the temperature of the recording head in order to stabilize the discharging amount of ink.
To describe them more precisely, for the ink jet recording head that discharges ink by utilization of such energy as described above, the temperature of the base plate (hereinafter, may also be referred to as a heater board), where the heat generating resistive elements and the recording head wiring circuit are arranged, is influenced by the printing patterns at the time of actual printing and the environmental temperature as well. Also, depending on the temperature of the heater board at the time of driving, the time required for the application of driving signal until the actuation of bubbling is caused to be varied. As a result, the printing patterns in actual printing and the environmental temperature exert influence on the time required for the application of driving signal until the discharge is conditioned to perform an actual printing normally when the ink jet recording apparatus is driven for actual printing that begins with the status of being at rest, that is, the status of the so-called “initial discharge performance”.
If the status of “initial discharge performance” is unfavorable, the influence that may be exerted on the actual printing becomes greater. As means for counteracting this condition, a method is adopted to perform preliminary ink discharges before printing by applying designated driving signals prior to the execution of the actual printing. However, this means requires the consumption of ink for the operation other than the actual printing.
Under the circumstances, a control method for controlling the temperature of the heater board within a designated range is taken as an effective measure in which temperature detecting means (diode sensor) is provided for detecting temperature on the heater board where the heaters are arranged for use of ink discharges, and the heaters for use of temperature control (sub-heaters), which are arranged in the vicinity of both end portions of the arrangement of heaters for use of ink discharges, and then, on the basis of the temperature detected by temperature detecting means, the heaters for use of temperature control are driven appropriately.
SUMMARY OF THE INVENTION
On the other hand, the performance required for the ink jet recording head at present should be such as to record in the image quality in precision higher still at recording speed faster still. Further, it is desired to make such head smaller still.
Now, therefore, in order to perform recording in an image quality higher still, it is required to discharge finer ink droplets under well-conditioned control. Also, in order to record at a recording speed faster still, it is required to increase the number of heaters for use of ink discharges. Then, for the attainment of the higher precision of recorded images at the faster recording speed, it is considered effective to adopt the structure of the so-called side shooter type where ink droplets are discharged in the direction perpendicular to the heater board which is the base plate having heat generating resistive elements for use of ink discharges formed therefor. For the recording head of side shooter type, the structure is adopted so that the ink supply into the head is made from the reverse side of each heat generating resistive element of the heater board by way of the through opening that penetrates the heater board. With the structure whereby to supply ink from the reverse side of the heater board, it becomes unnecessary to make the distance between the discharge ports and a recording medium larger owing to the presence of a member for supplying ink to the head. Consequently, the degradation of impact precision of discharged ink droplets can be prevented. Also, for the recording head of side shooter type, a plurality of discharge ports can be arranged on the plane with the advantages in forming a structure in which ink droplets of plural colors should be discharged.
However, any increased number of heaters on one heater board for the implementation of higher speed recording should present itself as a cause to make the heater board larger in size. Therefore, in order to make the size of the heater board as small as possible, there is a need for reducing the number of such elements as the aforesaid diode sensors and sub-heaters other than the regular heaters. Thus, the area occupied by them on the heater board should be made the smallest possible.
Here, therefore, with the purpose of attaining the provision of image quality in higher precision at higher speed of recording, and also, making the head smaller, the inventors hereof have simply attempted to reduce the number of diode sensors and sub-heaters for the recording head of the so-called side shooter type, where, as described above, heater lines for use of discharging ink of plural colors and ink discharge ports for use of plural colors are arranged on one heater board. Then, it is found that if the number of the diode sensors and sub-heaters is simply reduced, the “initial discharge performance” is degraded, and there occurs a problem that the color tone of recording images is not stabilized, among some others.
Under such circumstances, the inventors hereof have earnestly made a study to find the solution of such problems. As a result, it is ascertained that as compared with the recording head of the so-called edge shooter type where ink is discharge in the direction substantially horizontal to the heater board, these problems are encountered more conspicuously in the recording head of the side shooter mode. More precisely, it is found that in the mode of the side shooter recording head, a plurality of ink supply ports provided for the heater board demonstrate the he
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