Facsimile and static presentation processing – Static presentation processing – Memory
Reexamination Certificate
1998-05-06
2001-05-01
Gaffin, Jeffrey (Department: 2841)
Facsimile and static presentation processing
Static presentation processing
Memory
C358S001150, C358S001170, C358S001180, C382S172000
Reexamination Certificate
active
06226099
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing apparatus, such as a laser beam printer, that generates bit map data from print data which are input from the outside and prints the data, and to a memory medium that is employed to store a control program.
2. Related Background Art
A page printer, such as a laser beam printer, must store an output image for one page in a bit map memory. To do this, there are a full paint method, which requires a full page bit map, and a banding method, by which a band bit map covering a fractional portion of a page is employed to generate an image for one page.
The full paint method requires a bit map memory for one page, and data to be printed are transferred to a printing mechanism (a printer engine) after an image is generated on a bit map memory. According to this method, for example, a bit map memory of about 8 MB is required for an A3 size sheet at a resolution of 600 DPI. However, since an output image for one page can be generated even for a great amount of data, or for data that require a long time for image generation, the print output of input data is ensured.
According to the banding method, data to be printed for one page are stored as intermediate data in the apparatus. A bit map memory for a fractional portion of a page is used as a ring buffer (band buffer), and the generation and the transfer of an output image must be controlled by employing a synchronization signal that is output by a printing mechanism (printer engine).
Compared with the full paint method, the banding method can be performed with a smaller memory capacity, and as the generation (rendering) of an output image and a transfer of the output image to the printing mechanism (printer engine) can be performed at the same time, the processing speed is increased.
Conventionally, in the full paint method, a bit map memory for one page is required, and in the banding method, a bit map memory for a fractional portion of a page is required. The capacity of a bit map memory, therefore, increases in proportion to the resolution of a printing apparatus and to the size of the sheet that can be handled.
Compared with the full paint method, the conventional banding method must store data for a single page that is to be printed as intermediate data in the apparatus. Therefore, when the intermediate data for one page can not be stored, printing can not be performed.
Further, an image must be generated and transferred in consonance with a synchronization signal from the printing mechanism (printer engine). However, because of the enormous amount of intermediate data, an output image can not be generated within a determined time period, an overrun occurs, and as a result, printing can not be performed.
As is described above, although the conventional banding method can reduce the memory capacity that is required for a bit map memory, with this method, print data that are input sometimes can not be output.
SUMMARY OF THE INVENTION
To overcome the above shortcomings, it is one object of the present invention to perform, for each band, an encoding process (encoding and compression) to generate encoded data from bit map data that are generated each time intermediate data for one page are stored; and to perform, for each band, a decoding process (decoding and decompression) to obtain data for one page from the encoded data that are stored, so that a time required for the generation of bit map data to be printed does not exceed a predetermined time, and so that bit map memory capacity may be reduced.
To overcome the above described shortcomings, it is another object of the present invention to manage, for each band, identification information that indicates whether or not a encoding process (coding and compression) has been performed for bit map data that are to be generated, and to perform a decoding process (decoding and decompression) for the bit map data in consonance with the identification information, so that a fast printing process is provided by efficient encoding decoding processes.
To resolve the above described shortcomings, it is an additional object of the present invention to determine whether or not a time period that is required for generating bit map data in consonance with intermediate data exceeds a predetermined period of time; and when the time period exceeds the predetermined time, to encode, compress and store bit map data for one page that have been generated based on the intermediate data for one page, so that the printing process for intermediate data is ensured.
To resolve the above described shortcomings, it is a further object of the present invention to determine whether or not intermediate data for one page can be stored in storage means, and when the intermediate data for one page can not be stored in the storage means, to encode, compress and store bit map data for one page that have been generated based on the intermediate data for one page, so that the printing process for the intermediate data is ensured.
To achieve the above described objects, a printing apparatus according to the present invention, which generates bit map data from intermediate data and prints the bit map data, comprises:
generation means for, when the intermediate data for one page are stored in first storage means, generating bit map data, for each band, from the intermediate data for one page, which are stored in the first storage means, for encoding and compressing the bit map data that are generated, and for generating encoded data for each band; and
control means for, when the encoded data that are generated for each band by the generation means are stored in second storage means for one page, decoding and decompressing, for each band, the encoded data for one page, which are stored in the second storage means, and for reproducing bit map data for one page.
To achieve the above objects, a printing apparatus according to the present invention, which generates bit map data from intermediate data and prints the bit map data, comprises:
storage means for sorting and storing the intermediate data for each band;
encoding means for generating bit map data from the intermediate data that are stored in the storage means, and for encoding and compressing the bit map data that are generated;
management means for storing and managing, for each band, identification information that indicates whether or not the encoding means has performed a encoding process; and
decoding means for decoding and decompressing the encoded data that are encoded and compressed by the encoding means to reproduce the bit map data; and
control means for controlling the decoding means in consonance with the identification information that is stored and managed by the management means.
To achieve the above objects, a printing apparatus according to the present invention, which generates bit map data from intermediate data to print the bit map data, comprises:
determination means for determining, for each band, whether or not a time period for generation of bit map data based on the intermediate data exceeds a predetermined time period; and
compression means for, when the determination means determines that the time period for generation exceeds the predetermined time period, encoding and compressing the bit map data for one page that have been generated based on the intermediate data for one page.
To achieve the above objects, a printing apparatus according to the present invention, which generates bit map data from intermediate data and prints the bit map data, comprises:
determination means for determining whether or not storage means is available for storing the intermediate data for one page; and
compression means for, when the determination means determines that the storage means is not available for storing intermediate data for one page, encoding and compressing the bit map data for one page that have been generated based on the intermediate data for one page.
To achieve the above described objects, provided is a memory medium according to the present inventio
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Gaffin Jeffrey
Tran Thanh Y.
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