Ink jet record apparatus

Claim 1

An ink jet recording apparatus for printing image data on record paper by using a drop-on-demand ink jet head, said ink jet recording apparatus comprising: a multiple-nozzle ink jet head including a plurality of nozzles, a respective pressure chamber for each nozzle and a respective piezoelectric element provided adjacent to a surface of each pressure chamber, the plurality of nozzles being aligned on the multiple-nozzle ink jet head along a sub scan direction to cover a plurality of main scan lines of ink dots printed on the record paper extending in a main scan direction; selection means for selecting an operation mode of said ink jet head from a first mode and a second mode in accordance with input image information; control means for supplying a first drive signal to each of said piezoelectric elements of said ink jet head when the first mode is selected by said selection means and for supplying a second drive signal to each of said piezoelectric elements of said ink jet head when the second mode is selected by said selection means, the operation mode of said ink jet recording head being changeable from the first mode to the second mode or vice versa; first drive means for driving and operating said ink jet head in the first mode so that rows of ink dots of relatively small dot density are printed along the main scan direction on the record paper; and second drive means for driving and operating said ink jet head in the second mode so that row of ink dots of relatively great dot density are printed along the main scan direction on the record paper. said control means allowing ink dots at a first dot density P (dpi) to be printed in the main scan direction on the record paper by said ink jet head when the selection means selects the first mode, and allowing ink dots at a second dot density 2P (dpi) to be printed in the main scan direction on the record paper when the selection means selects the second mode, said first dot density being equal to half said second dot density, said ink jet recording apparatus further comprising paper feed means for feeding the record paper in the sub scanning direction by a length equal to a dot pitch 1(2P) when the selection means selects the second mode, said second drive means driving and operating the ink jet head in the second mode so that first rows of ink dots are printed on the record paper at the second dot density 2P (dpi) by a first scan in said main scan direction, then said paper feed means feeding the record paper by a length equal to 1/(2P), and said second drive means again driving and operating the ink jet head in the second mode so that second rows of ink dots are printed on the record paper at the second dot density 2P (dpi) by a second scan in said main scan direction.

Claim 9

A method for recording image data on record paper by using a drop-on-demand ink jet head with dot density varying capability, said ink jet head including a nozzle, a pressure chamber containing ink and communicating with the nozzle, and an oscillation plate having a piezoelectric element provided adjacent to the pressure chamber, said method comprising steps of: selecting an operation mode of said ink jet head from among a first mode and a second mode in accordance with input image information, the image data being printed on the record paper at a relatively low dot density when said ink jet head is driven and operated in the first mode but the image data being printed on the record paper at a relatively high dot density when said ink jet head is driven and operated in the second mode; supplying a first drive signal to said piezoelectric element of said ink jet head when the first mode of said ink jet head is selected in accordance with the input image information but supplying a second drive signal to said piezoelectric element when the second mode of said ink jet head is selected in accordance with the input image information; driving and operating said ink jet head in the first mode in response to the first drive signal supplied to said piezoelectric element such that an ink drop of relatively large size is ejected from the nozzle of said ink jet head to print a dot included in he image data on the record paper when said piezoelectric element is stressed, when the pressure chamber is refilled with ink when said piezoelectric element returns back to a non-stressed condition; driving and operating said ink jet head in the second mode in response to the second drive signal supplied to said piezoelectric element such that said pressure chamber is refilled with ink when said piezoelectric element is changed from a stressed condition to a non-stressed condition and than an ink drop of relatively small size is ejected from the nozzle of said ink jet head to print a dot included in the image data on the record paper when said piezoelectric element is again stressed; and repeating the aforementioned steps until all the dots of one complete page included in the image data are printed on the record paper.

Claim 10

A method for recording image data on record paper by using a drop-on-demand ink jet head with dot density varying capability, said ink jet head including a nozzle, a pressure chamber containing ink and communicating with the nozzle, and an oscillation plate having a piezoelectric element provided adjacent to the pressure chamber, said method comprising steps of: selecting an operation mode of said ink jet head from among a first mode and a second mode in accordance with input image information, the image data being printed on the record paper at a relatively low dot density when said ink jet head is driven and operated in the first mode but the image data being printed on the record paper at a relatively high dot density when said ink jet head is driven and operated in the second mode; supplying a first drive signal to said piezoelectric element of said ink jet head when the first mode of said ink jet head is selected in accordance with the input image information but supplying a second drive signal to said piezoelectric element when the second mode of said ink jet head is selected in accordance with the input image information; driving and operating said ink jet head in the first mode in response to the first drive signal supplied to said piezoelectric element such that an ink drop of relatively large size is ejected from the nozzle of said ink jet head to print a dot included in he image data on the record paper when said piezoelectric element is stressed, when the pressure chamber is refilled with ink when said piezoelectric element returns back to a non-stressed condition; driving and operating said ink jet head in the second mode in response to the second drive signal supplied to said piezoelectric element such that said pressure chamber is refilled with ink when said piezoelectric element is changed from a stressed condition to a non-stressed condition and than an ink drop of relatively small size is ejected from the nozzle of said ink jet head to print a dot included in the image data on the record paper when said piezoelectric element is again stressed; and repeating the aforementioned steps until all the dots of one complete page included in the image data are printed on the record paper.

Claim 11

A method for recording image data on record paper by using a drop-on-demand, multiple-nozzle ink jet head with dot density varying capability, said ink jet head including a plurality of nozzles, each of said nozzles communicating with a pressure chamber and including an oscillation plate having a piezoelectric element provided adjacent to the pressure chamber for each of the nozzles, said method comprising steps of: selecting an operation mode of said ink jet head from among a first mode and a second mode in accordance with input image information, the image data being printed on the record paper at a relatively low dot density P (dpi) when said ink jet head is driven and operated in the first mode but the image data being printed on the record paper data relatively high dot density P (dpi) when said ink jet head is driven and operated in the second mode; supplying a first drive signal to each of said piezoelectric elements of aid ink jet head when the first mode of said ink jet head is selected in accordance with the input image information and supplying a second drive signal to each of said piezoelectric elements when the second mode of said ink jet head is selected in accordance with the input image information; driving and operating said ink jet head in the first mode in response to the first drive signal supplied to said piezoelectric elements such that a row of ink drops of relatively large size aligned along a sub scan line is printed on the record paper in a main scan direction at a first dot density P (dpi) in one main scan; driving and operating said ink jet head in the second mode in response to the second drive signal supplied to each said piezoelectric element such that a first row of ink drops of relatively small size aligned along a sub scan line is printed on the record paper in the main scan direction at a second dot density Q (dpi) in a first main scan, then feeding the record paper in sub scan direction by a length equal to a dot pitch 1/Q corresponding to the second dot density Q, and again driving and operating said ink jet head in the second mode so that a second row of ink drops of the relatively small size along a sub scan line is printed on the record paper in the main scan direction at the second dot density Q (dpi) by a second main scan; and repeating the aformentioned steps until all the dots of one complete page included in the image data are printed on the record paper.

Claim 12

A method for recording image data on record paper by using a drop-on-demand, multiple-nozzle ink jet head with dot density varying capability, said ink jet head including a plurality of nozzles, each of said nozzles communicating with a pressure chamber and including an oscillation plate having a piezoelectric element provided adjacent to the pressure chamber for each of the nozzles, said method comprising steps of: selecting an operation mode of said ink jet head from among a first mode and a second mode in accordance with input image information, the image data being printed on the record paper at a relatively low dot density P (dpi) when said ink jet head is driven and operated in the first mode but the image data being printed on the record paper data relatively high dot density P (dpi) when said ink jet head is driven and operated in the second mode; supplying a first drive signal to each of said piezoelectric elements of aid ink jet head when the first mode of said ink jet head is selected in accordance with the input image information and supplying a second drive signal to each of said piezoelectric elements when the second mode of said ink jet head is selected in accordance with the input image information; driving and operating said ink jet head in the first mode in response to the first drive signal supplied to said piezoelectric elements such that a row of ink drops of relatively large size aligned along a sub scan line is printed on the record paper in a main scan direction at a first dot density P (dpi) in one main scan; driving and operating said ink jet head in the second mode in response to the second drive signal supplied to each said piezoelectric element such that a first row of ink drops of relatively small size aligned along a sub scan line is printed on the record paper in the main scan direction at a second dot density Q (dpi) in a first main scan, then feeding the record paper in sub scan direction by a length equal to a dot pitch 1/Q corresponding to the second dot density Q, and again driving and operating said ink jet head in the second mode so that a second row of ink drops of the relatively small size along a sub scan line is printed on the record paper in the main scan direction at the second dot density Q (dpi) by a second main scan; and repeating the aformentioned steps until all the dots of one complete page included in the image data are printed on the record paper.