Facsimile and static presentation processing – Static presentation processing – Size – resolution – or scale control
Reexamination Certificate
2000-03-28
2003-05-27
Wallerson, Mark (Department: 2622)
Facsimile and static presentation processing
Static presentation processing
Size, resolution, or scale control
C358S001500, C358S001900, C358S001110, C358S001130, C358S001160, C358S501000, C358S504000, C358S401000, C358S404000, C358S406000
Reexamination Certificate
active
06570672
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a printing system and method and, more particularly, to a printing system and method allowing a low-resolution printer to perform printing based on print data prepared at high resolution.
2. Description of Related Art
Recently, printers have become increasingly higher in resolution, and laser printers capable of printing at a resolution as high as 1200×1200 dpi have become commercially available. In order to increase the resolution of a printer, it is required to increase a kind of response speed of the printer, for example, by adopting a photoconductive member responsive to a laser beam even when its irradiation time is short, by increasing the modulation frequency of the laser beam, or by speeding print data transmission to a laser beam drive circuit. Further, it is required to increase mechanical accuracy, for example, by increasing rotation accuracy of a laser scanner, which is crucial to formation of a latent image on a photoconductive member based on image data, by increasing rotation accuracy of the photoconductive member, or by increasing image development and transfer accuracy, which is crucial to development of a latent image with toner and transfer of a toner image to recording paper. Especially, when the circumference of the photoconductive member is less than the length of one page of printing paper, formation of a latent image, development of the latent image, and transfer of a developed image concurrently occur on the same photoconductive member. As a result, paper feed accuracy at the image transfer portion becomes a determinant of the overall accuracy of the printer.
As described above, since a laser printer attaining a high resolution of, for example, 1200×1200 dpi requires higher response speed and accuracy, such a printer becomes very expensive compared to a laser printer having a resolution of 600×600 dpi.
The maximum output speed, at which the printer resolution determined by the above-described mechanical accuracy is stably attained, is termed the process speed of the printer. For example, in the printer using a photoconductive member whose circumference is less than the paper length, the process speed is determined by the paper feed speed at the image transfer portion, and thus the paper feed speed is preset such that the printer can attain a specified resolution.
A direction along which a laser beam is scanned is termed herein a scanning direction, while a direction perpendicular to the scanning direction is termed a sub-scanning direction. The process speed is a speed pertinent to the sub-scanning direction.
Aiming at an increase in resolution, the response speed can be increased to some extent by making the process speed lower than its preset speed. Thus, the response speed will be excluded from the major factors limiting the resolution. However, in this case, the printing speed will be reduced instead. In addition, even when the process speed is reduced, limited mechanical accuracy, such as limited paper feed accuracy, is hard to resolve and directly defines the limitations of the printer. Increasing other mechanical accuracy, for example, by maintaining rotation accuracy of the laser beam scanner high enough to allow its high-speed rotation will result in a price increase. The laser beam scanner, if rotated at high speed, produces noise, and an additional measure is required to reduce the noise, resulting in a further price increase.
Under the above-described circumstances, demands for high-quality printouts at the lowest price are great. Also, there are demands for a laser printer that is even inexpensive and of low-resolution but capable of producing printouts using high-quality image data prepared for a high-resolution laser printer. Such a printer, if available, makes it unnecessary to prepare print data separately for resolutions varying from printer to printer.
SUMMARY OF THE INVENTION
In view of the foregoing, a first object of the invention is to provide a printing system and method that allow a low-resolution printer to produce printouts perceived to be comparable to those produced by a high-resolution printer. A second object of the invention is to provide a printing system and method in which printing is selectively performed at a high resolution and a normal resolution. A third object of the invention is to provide a printing system and method in which no displacements are produced in boundaries of a printed image.
To achieve the first and the second objects, a printing system according to one aspect of the invention includes a memory device that stores image data; a first developer that develops print data into first image data having a first resolution in two crosswise directions, the first image data being stored in the memory device; a rearranger that breaks the first image data stored in the memory device into blocks of N consecutive lines, N being not smaller than two, and retrieves therefrom the first image data in blocks of N consecutive lines to rearrange N lines of retrieved image data into one line of image data according to a predetermined rearrangement scheme; a printing device that prints at the second resolution lower than the first resolution; a first printing controller that controls the printing device to execute printing based on the image data rearranged by the rearranger; a second developer that develops print data into second image data having a second resolution in two crosswise directions, the second image data being stored in the memory device; a second printing controller that controls the printing device to execute printing based on the second image data stored in the memory device; and a switching device that switches between the first developer and the second developer prior to development of print data.
In the printing system as described above, the switching device switches between a fine mode and a normal mode when print data is stored in the memory device. In the fine mode, print data is developed into the first image data having the first resolution and stored in the memory device. On the other hand, in the normal mode, print data is developed into the second image data having the second resolution that agrees with the capability of the printing device, and is stored in the memory device.
In the fine mode, the first developer develops print data into the first image data having the first resolution in two crosswise directions. The first image data is stored in the memory device. Then the rearranger breaks the first image data into blocks of N consecutive lines (N being not smaller than two), retrieves the first image data in blocks of N consecutive lines from the memory device, and rearranges the retrieved image data according to a predetermined rearrangement scheme. Finally, the first printing controller controls the printing device to execute printing based on the image data rearranged by the rearranger.
On the other hand, in the normal mode, print data is developed into the second image data having the second resolution in two crosswise directions. The second image data is stored in the memory device. The second printing controller reads the second image data from the memory device and controls the printing device to execute printing based on the read image data, which is not rearranged by the rearranger.
Accordingly, in the fine mode, for example, image data having 2400×1200 dpi is produced based on the image data developed to have a first resolution of 1200×1200 dpi and stored in the memory device. Then, using a printer having a process speed of 600 dpi, such printouts can be produced that appear to be of high resolution and as if produced by a printer having a process speed of 1200 dpi.
On the other hand, on the normal mode, printing can be performed, for example, at a second resolution of 600 dpi.
According to another aspect of the invention, the printing system further includes a mode determiner that determines which mode is designated as a print mode, the fine mode in which printing is exec
Brother Kogyo Kabushiki Kaisha
Lamb Twyler
Oliff & Berridg,e PLC
Wallerson Mark
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