Printer using direct memory access and refreshing

A printer for receiving print data from an external device and printing an image on a recording medium by using a plurality of printheads, comprising:

• storage means for storing the print data in correspondence with said plurality of printheads;
• print means for receiving the print data from said storage means and printing the image on the recording medium by outputting the print data to said plurality of printheads;
• address storage means for storing read start and end addresses of each of the print data stored in correspondence with said plurality of printheads;
• and
• transfer means for reading out the print data from addresses, in said storage means, which are between the read start and end addresses stored in said address storage means, and transferring the print data to said corresponding printheads, wherein the print data corresponding to said plurality of printheads are stored at different addresses in said storage means, and a plurality of lower bits of the addresses are the same.

A printer for receiving print data from an external device and printing an image on a recording medium by using a plurality of printheads, comprising:

• storage means for storing the print data in correspondence with said plurality of printheads;
• print means for receiving the print data from said storage means and printing the image on the recording medium by outputting the print data to said plurality of printheads;
• signal generation means for generating an optional memory signal indicating that an optional memory is added to said storage means;
• and
• address changing means for changing an address for accessing said storage means in accordance with the optional memory signal, wherein said address changing means includes:
• a first circuit separating a read address signal for said storage means from an address signal from a main control circuit for controlling said storage means, shifting the address signal from the main control circuit, and outputting the shifted signal as an address signal for said storage means, and
• a second circuit shifting a part of an address signal for reading out the print data from said storage means, and outputting the shifted signal as an address signal for said storage means.

A printer for receiving print data from an external device and printing an image on a recording medium by using a plurality of printheads, comprising:

• storage means for storing the print data in correspondence with said plurality of printheads;
• print means for receiving the print data from said storage means and printing the image on the recording medium by outputting the print data to said plurality of printheads;
• signal generation means for generating an optional memory signal indicating that an optional memory is added to said storage means;
• and
• address changing means for changing an address for accessing said storage means in accordance with the optional memory signal, wherein the memory areas, in said storage means, which correspond to said plurality of printheads are set such that absolute values of the addresses of the print data become the same.

A data processing method applied to a printer including print means for receiving print data from an external device and printing an image on a recording medium by using a plurality of printheads, comprising the steps of:

• storing the print data in correspondence with the plurality of printheads into a memory;
• consecutively reading out the print data corresponding to each of the plurality of printheads from the memory by a predetermined amount using a direct memory access method when a read operation for the print data stored in the memory is designated by the print means;
• printing the image on the recording medium by receiving the print data and outputting the print data to the plurality of printheads;
• and
• refreshing or accessing the memory after the read operation is completed in said reading step,
• wherein the predetermined amount is a data amount which corresponds to each of the plurality of printheads, and a period of time required for consecutively reading out the data amount ensures a refresh interval required by the memory.

A data processing method applied to a printer for receiving print data from an external device and printing an image on a recording medium by using a plurality of printheads, comprising the steps of:

• storing the print data in correspondence with the plurality of printheads into a first memory;
• storing read start and end addresses of each of the print data in correspondence with the plurality of printheads stored in the first memory, into a second memory;
• reading out the print data from addresses, in the first memory, which are between the read start and end addresses stored in the second memory, and transferring the print data to the corresponding printheads;
• and
• printing the image on the recording medium by receiving the print data from the first memory and outputting the print data to the plurality of printheads,
• wherein the print data corresponding to the plurality of printheads are stored at different addresses in the first memory, and a plurality of lower bits of the addresses are the same.

A data processing method applied to a printer for receiving print data from an external device and printing an image on a recording medium by using a plurality of printheads, comprising the steps of:

• storing the print data in correspondence with the plurality of printheads into a memory;
• generating an optional memory signal indicating that an optional memory is added to the memory if the optional memory is added;
• changing an address for accessing the memory in accordance with the optional memory signal;
• and
• printing the image on the recording medium by receiving the print data from the memory and outputting the print data to the plurality of printheads,
• wherein said changing step includes the steps of:
• (1) separating a read address signal for the memory from an address signal from a main control circuit for controlling the memory, shifting the address signal from the main control circuit, and outputting the shifted signal as an address signal for the memory;
• and
• (2) shifting a part of an address signal for reading out the print data from the memory, and outputting the shifted signal as an address signal for the memory.

A data processing method applied to a printer for receiving print data from an external device and printing an image on a recording medium by using a plurality of printheads, comprising the steps of:

• storing the print data in correspondence with the plurality of printheads into a memory;
• generating an optional memory signal indicating that an optional memory is added to the memory if the optional memory is added;
• changing an address for accessing the memory in accordance with the optional memory signal;
• printing the image on the recording medium by receiving the print data from the memory and outputting the print data to the plurality of printheads;
• wherein the memory areas, of the memory, which correspond to the plurality of printheads are set such that absolute values of the addresses of the print data become the same.

A printing apparatus having a plurality of printheads, each arraying a plurality of printing elements and printing in a different color on a recording medium, comprising:

• a memory, having a plurality of areas corresponding to color components of print data, for storing the color components of the print data in the respective areas;
• control means for controlling an access operation to said memory from an external circuit, and controlling a refresh operation on said memory;
• and
• read means for reading out the print data, corresponding to each of the plurality of printheads, stored in said memory by a predetermined amount,
• wherein, when reading out the print data with said read means, each time the predetermined amount of the print data corresponding to each of said plurality of printheads is read out, said control means enables the access operation to said memory and the refresh operation on said memory.

A printing apparatus for printing on a recording medium by using a plurality of printheads, each arraying a plurality of printing elements in an arraying direction, comprising:

• mounting means for mounting the plurality of printheads along a direction different from the arraying direction of the plurality of printing elements;
• a memory, having a plurality of areas corresponding to the plurality of printheads, for storing print data corresponding to the plurality of printheads in the respective areas;
• conveyance means for conveying the recording medium in the direction in which the plurality of printheads are mounted;
• storage means for storing information indicating each of the plurality of areas in said memory;
• and
• control means for updating the information stored in said storage means based on a signal indicating a start for transferring the print data corresponding to each of the plurality of printheads,
• wherein, in correspondence with a signal indicating a start for transferring print data to a predetermined one of the plurality of printheads, said control means updates information indicating areas in which print data corresponding to the rest of the plurality of printheads are stored.

A printing apparatus for printing on a recording medium by using a plurality of printheads, comprising:

• a memory, having a plurality of areas corresponding to the plurality of printheads, for storing print data corresponding to the plurality of printheads in the respective areas;
• a slot to which an optional memory is attached;
• an address output circuit for outputting an address to access said memory and the optional memory;
• and
• address change means for changing an address used for accessing said memory and the optional memory such that an absolute address is not changed regardless of whether or not the optional memory is attached to said slot.