Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-11-13
2002-03-05
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06352327
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus and print control method and, more particularly, to a printing apparatus capable of performing printing in accordance with an ink-jet printing method, and print control method thereof.
Recently, as office automation devices such as personal computers, word processors or the like, are widely used, various printing methods and printing apparatuses are developed for printing data inputted by these apparatuses. Particularly, the printing apparatus adopting the ink-jet printing method is advantageous because the apparatus can perform full-color image printing despite its small size and inexpensive price, thus becoming rapidly popular.
In the ink-jet printing method, since ink droplets are discharged to a print medium to perform printing, the printing apparatus comprises means for recovering reliability of discharging ink droplets. Examples of recovery are: suction recovery in which ink is compulsorily suctioned from the printhead and drawn off as necessary; preliminary discharge recovery in which ink is periodically discharged to a predetermined position; a wiping operation in which the surface of the printhead where ink discharge nozzles are formed is wiped by a blade made of rubber or the like to remove ink on the surface; and so forth. Furthermore, by integrating a printhead and an ink tank into a cartridge of a maintenance-free disposable type, the operability and applicability for users are improved.
Meanwhile, as an attempt to improve the quality of printed images, a simplified color printing apparatus has been developed, taking advantage of the exchangeability of disposable printheads. In the simplified color printing apparatus, a monochrome printing apparatus can easily become a color printing apparatus by a user exchanging the printhead for monochrome printing with the printhead for color printing. Furthermore, various types of high-quality printing apparatuses have been developed, taking advantage of the exchangeability of disposable heads, as exemplified by a color printing apparatus capable of simultaneously printing images in plural colors by having a plurality of printheads, or an apparatus incorporating a plurality of printheads for printing at different densities of the same color by simultaneously using plural inks having the same color (tone) but different densities.
In addition, higher printing speed is also a vital technical issue, along with higher quality. To achieve this, the number of ink discharge nozzles in a printhead is increased (multi-nozzle printhead), having been supported by developments in semiconductor manufacturing technology. Although increasing the number of nozzles results in increase in the power supply in the apparatus, by virtue of adopting the time-divisional block driving method where nozzles are segmented into blocks and printing elements are driven block by block instead of simultaneously driving the entire printing elements to discharge ink from all the nozzles, it is possible to minimize the electric power consumed at once.
Taking into account that different densities of ink are used for gradation printing or a plurality of printheads, each using a particular color ink, are used for color printing, the controller which performs driving control and printing control using a printhead, and recovery mechanism of the printhead must be able to cope with any situations that may occur.
In a case of a printhead which discharges black ink for monochrome printing, color ink for color printing, or dark-colored ink and light-colored ink of the same color, all the ink is not always discharged under the same conditions. There are inks and printheads which require a large amount of energy, whereas there are inks and printheads which require a small amount of energy.
In order to simply realize high-speed printing by using a printhead, a larger amount of energy per unit time may be supplied. However, taking the diversity of printheads into account, a conventional printing apparatus limits its printing speed to a certain speed based on the assumption that the printhead which consumes the maximum electric power suppliable is driven, because the power capacity of the printing apparatus is limited. Therefore, even if a printhead consuming a small amount of electric power is used, there is a case where high-speed printing cannot be attained although such printhead has the potential to perform high-speed printing with a larger amount of energy per unit time.
Furthermore, in the conventional printing apparatus, the timing of recovery control for a printhead is predetermined based on the standard timing of a printhead having the least discharge reliability. Therefore, even if a printhead having high discharge reliability is used, recovery operation is automatically performed even when the recovery control is unnecessary. By performing recovery operation more than necessary, a problem of reduced printing speed occurs despite the fact that higher throughput is possible if the recovery operation is not performed.
SUMMARY OF THE INVENTION
The present invention is made in consideration of the above situation, and has as its object to provide a printing apparatus and print control method for achieving high throughput by performing optimized print control in accordance with the type and the number of printheads used, in a case where plural types of printheads are used.
The printing speed of a printing apparatus depends upon various aspects, e.g., the time required for driving printing elements, the capacity of the power source of the printing apparatus, the time necessary for ink refill which largely attributes to the printing speed in the ink-jet printing apparatus and so on. According to the present invention, each of the above aspects which affects the printing speed is considered in accordance with the type and the number of printheads mounted to the printing apparatus, and the driving period of the printhead as well as conditions related to various print controls are optimized so as to achieve printing at high speed.
According to one aspect of the present invention, the foregoing object is attained by providing a printing apparatus for performing printing on a print medium by mounting a printhead having a plurality of print elements and using the printhead, comprising: a mounting portion in which at least one printhead can be mounted; scanning means for reciprocally scanning the printhead; detecting means for detecting a type of printhead and a number of printheads mounted; first deciding means for deciding a driving condition of the printhead based on a result of detection by the detecting means; second deciding means for deciding scanning speed of the scanning means based on the driving condition decided by the first deciding means; and control means for executing printing by driving the printhead based on the driving condition decided by the first deciding means, and performing print operation by driving the scanning means based on the scanning speed decided by the second deciding means.
Herein, the printhead may be an ink-jet printhead which performs printing by discharging ink. In this case, it is preferable that the printhead comprises an electrothermal transducer for generating heat energy in order to discharge ink by utilizing the heat energy.
Furthermore, it is preferable that the printing apparatus comprises recovery means for performing recovery operation on the printhead; and recovery control means for setting a recovery condition of the recovery means based on the result of detection by the detecting means and executing the recovery means in accordance with the set recovery condition. The aforementioned recovery condition includes a time interval for performing preliminary discharge, a wiping interval for wiping an ink discharge surface of the printhead, and a time interval for performing suction recovery.
The printhead mentioned above includes a first head for discharging black ink; a second head for discharging yellow ink; a third head for discharging magenta ink; a
Iwasaki Osamu
Kanematsu Daigoro
Nishikori Hitoshi
Ohtsuka Naoji
Takahashi Kiichiro
Canon Kabushiki Kaisha
Feggins K.
Fitzpatrick ,Cella, Harper & Scinto
Le N.
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