Canon Aptex

Fumio Miyahara

Hideaki Kishida

Shigeru Inose

Yasuhiro Hamada

A printer requires no print buffer in a printer engine, and can efficiently use an image memory for bit-mapping print data into a print image. An enable signal for designating transfer of data for one page from a formatter to the engine is output in response to a request signal from the engine for requesting transmission of print data for one line. When a clock signal for requesting transfer of print data is output from the engine to the formatter in response to this enable signal, print image data is transferred from the formatter to the engine in synchronism with the clock signal and further transferred to a printhead to print an image. As to the nozzles, on the right and left ends of the printhead, which are not used for a print operation, a right margin area and a nozzle area used for a print operation are set in a data transfer circuit. With this operation, '0' is first set to a print data signal in the data transfer circuit, and reference clocks used for transferring data to the printhead are counted for the number corresponding to right margin area of the printhead. When the count operation is completed, a signal becomes active, and subsequently, print image data is transferred. When the number of reference clocks coincides with the number of nozzles corresponding to the print area, this is set to print data again. This operation is repeatedly performed for each line.

Printer including a formatter and a printing unit without a memory

A printer includes a full-line type printhead which can correct variations in the ink discharge amounts from the respective nozzles, and density unevenness of a printed image due to variations in the operations of many driving circuits in the printhead and changes in the internal temperature or a temperature gradient of the printhead, and can obtain a high-quality printed image without density unevenness in consideration of the print conditions and changes in operation environmental temperature. A pre-heating operation is performed by selecting an optimal pre-pulse signal for each nozzle of the printhead on the basis of information stored in an EEPROM of the printhead and pre-pulse selection data associated with each nozzle of the printhead. A heat signal is also generated to obtain a main pulse suitable for each IC of a printhead corresponding to an ink of each color. In addition, the internal temperature of the printhead or printing density information from the printhead is monitored. If the internal temperature or the printing density is high, control is performed to inhibit a pre-pulse selection signal from being output while applying pre-pulse and main pulse signals to each nozzle heater of the printhead, which is used for a print operation.

Printer

In a color printer, in order to perform a high-speed print operation and ensure a refresh operation and the like of an image memory, print images which correspond to a plurality of printheads, and are bitmapped and stored in a bitmap RAM in units of colors are consecutively read out and DMA-transferred by 16 bits at a time when a read operation is designated. After this DMA operation, the refresh operation of the bitmap RAM or access to the RAM is permitted. The printer includes the same number of latch circuits as that of printheads (e.g., four). Each latch circuit stores a data transfer start address (TOPA) and a data transfer end address (ENDA) in the bitmap RAM. With this arrangement, image data can be efficiently read out. If the capacity of the bitmap RAM is small, an upper address bit in the bitmap RAM is shifted to switch discontinuous addresses to continuous addresses on the bitmap memory side. If an optional memory is implemented, the normal addressing is restored to flexibly cope with a change in the capacity of the image memory.

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Sagamihara, Japan

Fumio Miyahara