This invention relates to a printing apparatus and, more particularly to a printing apparatus having a printhead which performs printing in accordance with an ink-jet printing method.
A conventional printer having a plurality of print modes employs gate circuits to obtain selection pulses to select print elements as parts of a printhead for printing in accordance with one of the print modes.
FIG. 10 is a block diagram showing selection-pulse generators of the conventional printer having two print modes. When a drive trigger indicating the start of printing is inputted from a controller (not shown) of the printer a selector 80 selects one of two selection-pulse generators 81. The selector 80 operates in accordance with a print-mode signal similarly inputted from the controller. Next, the selected selection-pulse generator outputs six signals COM11, COM12, COM21, COM22, UPPER ENABLE and LOWER ENABLE, to a head driver 83, at a predetermined period. On the other hand, a heat-pulse generator 82 generates a heat pulse based on a control signal (not shown) inputted via an address bus and a data bus provided in the controller, and also outputs the heat pulse to the head driver 83. The head driver 83 drives a printhead 84 based on these input signals.
Recently, print speed has become increasingly higher, and high-speed printing using a printhead having a large number of print elements (e.g., heaters or ink-discharge nozzles) has been proposed. However, with increase of the number of print elements, complicated printhead controls such as interlaced drive and/or print controls in accordance with a plurality of print modes are required. In consideration of requirements such as apparatus downsizing, cutting costs and high-speed printing, it is difficult to implement such complicated controls with gate circuits.
Accordingly, it is an object of the present invention to provide a printing apparatus and print-control method which enables complicated printhead control without a complicated logic circuit.
According to one aspect of the present invention, the foregoing object is attained by providing a printer for printing an image on a printing medium by using a printhead including a plurality of print elements, comprising: selection means for selecting print elements from the plurality of print elements; memory means for storing a selection pattern used by the selection means; and selection control means for controlling the selection means so as to read the selection pattern stored in the memory means and select the print elements from the plurality of print elements, in accordance with the read selection pattern.
According to another aspect of the present invention, the foregoing object is attained by providing a print control method of controlling print operation to print an image on a print medium by using a printhead including a plurality of print elements, comprising: a reading step of reading a selection pattern from a storage medium; and a selection step of selecting print elements from the plurality of print elements, based on the read selection pattern.
In accordance with the present invention as described above, for selecting print elements to perform print operation using a plurality of print elements, a selection pattern related to the selection is stored in the memory means, then the stored selection pattern is read, and the selection is performed based on the read selection pattern. The selected print elements are driven for printing.
Note that the selection pattern stored in the memory means is rewritable. The memory means includes a RAM.
Then, a new selection pattern and an address of the memory means for storing the new selection pattern are inputted from an external device. The selection pattern stored in the memory means may be rewritten based on the input new selection pattern and the corresponding address.
The selection pattern may be stored in the memory means in the form of a table.
On the other hand, the control means issues a trigger signal to start a print operation. Upon inputting the trigger signal, an address of the memory means where the selection pattern is stored is generated, and a read trigger signal is generated for reading the selection pattern from the memory means. Upon inputting the trigger signal, a head address of the selection pattern is generated, thereafter, in synchronization with the generation of the read trigger signal, the address is incremented by one. The selection pattern is sequentially read by the increment of the address. When the print operation corresponding to all the print elements has been completed, the address is reset.
Note that the printhead may be an ink-jet printhead which performs printing by discharging ink, or a printhead which discharges ink by utilizing thermal energy. The latter printhead may have thermal-energy generators for generating thermal energy to be provided to the ink.
The printhead may be a color printhead. In this case, the printhead comprises a first printhead unit for discharging yellow ink, a second printhead unit for discharging cyan ink, a third printhead unit for discharging magenta ink, and a fourth printhead unit for discharging black ink.
The invention is particularly advantageous since various complicated print controls can be performed without complicated logic circuit.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same name or similar parts throughout the figures thereof.