Method and apparatus for controlling raster scan printer

Claim 1

An apparatus for controlling a raster scan printer comprising: a bit map memory for storing bit information corresponding to print dots with a bit sequence direction being in a raster scan direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; and means for reading said bit information from said bit map memory and sending said bit information to the raster scan printer having a print are of words in the raster scan direction by m rasters in a sheet feed direction; wherein addresses of said bit map memory ascend in the sheet feed direction along said helical ring; wherein a memory width of said bit map memory in the sheet feed direction is n rasters which is smaller than m rasters of said raster scan printer; wherein an address of a word adjacent in the raster scan direction to another word under consideration of the bit map memory is given by adding n rasters to the address of the word under consideration; wherein a memory capacity of said bit map memory is a predetermined amount larger than l·n words; and wherein each ring of said helical ring is shifted by one word every n rasters in the raster scan direction.

Claim 2

An apparatus for controlling a raster scan printer comprising: a bit map memory for storing bit information corresponding to print dots with a bit sequence direction being in a raster scan direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; and means for reading said bit information from said bit map memory and sending said bit information to the raster scan printer having a print are of words in the raster scan direction by m rasters in a sheet feed direction; wherein addresses of said bit map memory ascend in the sheet feed direction along said helical ring; wherein a memory width of said bit map memory in the sheet feed direction is n rasters which is smaller than m rasters of said raster scan printer; wherein an address of a word adjacent in the raster scan direction to another word under consideration of the bit map memory is given by adding n rasters to the address of the word under consideration; wherein a memory capacity of said bit map memory is a predetermined amount larger than l·n words; and wherein each ring of said helical ring is shifted by one word every n rasters in the raster scan direction.

Claim 3

An apparatus for controlling a raster scan printer comprising: a bit map memory for storing bit information corresponding to print dots with a bit sequence direction in a raster scan direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; and means for reading said bit information from said bit map memory and sending said bit information to the raster scan printer having a print area of words in the raster scan direction by m rasters in a sheet feed direction; wherein addresses of said bit map memory ascend in the sheet feed direction along said helical ring; wherein a memory width of said bit map memory in the sheet feed direction is n rasters which is smaller than m rasters of said raster scan printer; wherein an address of a word adjacent in the raster scan direction to another word under consideration of the bit map memory is given by adding n rasters to the address of the word under consideration; wherein an address for the first word of the first raster of the bit map memory is given by a residual address of m rasters and n rasters, plus one; wherein a memory capacity of said bit map memory is a predetermined amount larger than (-1)×(n+m); and wherein each ring of said helical ring is shifted by one word every n rasters in the raster scan direction.

Claim 4

An apparatus for controlling a raster scan printer comprising: a bit map memory for storing bit information corresponding to print dots with a bit sequence direction in a raster scan direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; and means for reading said bit information from said bit map memory and sending said bit information to the raster scan printer having a print area of words in the raster scan direction by m rasters in a sheet feed direction; wherein addresses of said bit map memory ascend in the sheet feed direction along said helical ring; wherein a memory width of said bit map memory in the sheet feed direction is n rasters which is smaller than m rasters of said raster scan printer; wherein an address of a word adjacent in the raster scan direction to another word under consideration of the bit map memory is given by adding n rasters to the address of the word under consideration; wherein an address for the first word of the first raster of the bit map memory is given by a residual address of m rasters and n rasters, plus one; wherein a memory capacity of said bit map memory is a predetermined amount larger than (-1)×(n+m); and wherein each ring of said helical ring is shifted by one word every n rasters in the raster scan direction.

Claim 5

A method for controlling a raster scan printer comprising the steps of: storing bit information corresponding to print dots in a bit map memory sequentially in a sheet feed direction and consecutively in a raster scan direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; reading said bit information from said bit map memory in the raster scan direction and sending the bit information to said raster scan printer; storing bit information corresponding to print dot into an area of said bit map memory from which bit information has been read; and reading the latter bit information and sending the latter bit information to said raster scan printer.

Claim 6

A method for controlling a raster scan printer comprising the steps of: storing bit information corresponding to print dots in a bit map memory sequentially in a sheet feed direction and consecutively in a raster scan direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; reading said bit information from said bit map memory in the raster scan direction and sending the bit information to said raster scan printer; storing bit information corresponding to print dot into an area of said bit map memory from which bit information has been read; and reading the latter bit information and sending the latter bit information to said raster scan printer.

Claim 8

A method for controlling a raster scan printer comprising the steps of: temporarily storing one part of dot data to be printed in a bit map memory having a memory capacity less than l×m bits, said raster scan printer having a printable area of dot data of words in a raster scan direction by m rasters in a sheet feed direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; reading said dot data from said bit map memory and supplying said dot data to said raster scan printer, and simultaneously storing a remaining part of the dot data to be printed in a region of said bit map memory where said reading and supplying operation is finished; and reading said remaining part of dot data from said bit map memory after said reading and supplying operation and supplying said remaining part of dot data to the raster scan printer; wherein said bit map memory is used for storing dot data to be printed so that an address increasing direction of said bit map memory corresponds to said sheet feed direction, and first parts from a top to n rasters in the sheet feed direction are partitioned as a first print area, and the dot data of l×m bits to be printed are assigned and stored in addresses of the bit map memory in the raster scan direction in word units in each of said first parts along said helical ring; wherein said dot data is successively read in the raster scan direction and is supplied to the raster scan printer and then second parts after n+1 rasters in the sheet feed direction are partitioned as a second print area, and the dot data of l×m bits to be printed are assigned and stored in addresses of the bit map memory in the raster scan direction in word units in each of said second parts; wherein said dot data is successively read in the raster scan direction and is supplied to the raster scan printer; and wherein each ring of said helical ring is shifted by one word every n rasters in the raster scan direction.

Claim 9

A method for controlling a raster scan printer comprising the steps of: temporarily storing one part of dot data to be printed in a bit map memory having a memory capacity less than l×m bits, said raster scan printer having a printable area of dot data of words in a raster scan direction by m rasters in a sheet feed direction, said bit map memory being in the form of a helical ring to permit said bit information to be stored in a sequential manner in said bit map memory; reading said dot data from said bit map memory and supplying said dot data to said raster scan printer, and simultaneously storing a remaining part of the dot data to be printed in a region of said bit map memory where said reading and supplying operation is finished; and reading said remaining part of dot data from said bit map memory after said reading and supplying operation and supplying said remaining part of dot data to the raster scan printer; wherein said bit map memory is used for storing dot data to be printed so that an address increasing direction of said bit map memory corresponds to said sheet feed direction, and first parts from a top to n rasters in the sheet feed direction are partitioned as a first print area, and the dot data of l×m bits to be printed are assigned and stored in addresses of the bit map memory in the raster scan direction in word units in each of said first parts along said helical ring; wherein said dot data is successively read in the raster scan direction and is supplied to the raster scan printer and then second parts after n+1 rasters in the sheet feed direction are partitioned as a second print area, and the dot data of l×m bits to be printed are assigned and stored in addresses of the bit map memory in the raster scan direction in word units in each of said second parts; wherein said dot data is successively read in the raster scan direction and is supplied to the raster scan printer; and wherein each ring of said helical ring is shifted by one word every n rasters in the raster scan direction.