Typewriting machines – Including control of format by programmed-control-system
Reexamination Certificate
1999-11-17
2001-03-06
Hilten, John S. (Department: 2854)
Typewriting machines
Including control of format by programmed-control-system
C400S070000, C400S061000
Reexamination Certificate
active
06196735
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an interface system for watching the status of a stencil printer when printing data generated by a computer is output to the stencil printer.
2. Description of the Related Art
A stencil printer is sometimes connected to a computer by way of an interface system to print on request from the computer. As a printer driver installed in the computer, there has been known one which has function of watching the status of the stencil printer. When printing data are transmitted to the interface system by way of the printer driver from the computer, the interface system analyzes the printing data and converts the data to raster data. The interface system outputs the raster data as page data and the stencil printer prints on the basis of the page data. The interface system is provided with a status control means which sets instruction on the action of the stencil printer on request from the computer. The interface system takes information on whether the stencil printer is in a stopped state, in action, or in an error state as status information through the status control means and stores the information in an updated status memory means. The interface system sends the updated status of the stencil printer on request from the computer. The printer driver of the computer outputs request to switch the direction of data transfer to the interface system when the status information becomes necessary during transfer of the printing data, and the interface system sends the updated status information in a predetermined data length to the computer upon receipt of the request.
During receiving the status information, the printer driver transfers and receives the status information in a fixed format wherein it outputs request to switch the direction of data transfer to the printing data transfer direction after it receives the predetermined data length. Further there has been known a variable format wherein the printer driver watches the time interval between adjacent series of data (time-out period) at a breakpoint of status information from the interface system, recalculates the time- out period each time it receives a series of data, and outputs request to switch the direction of data transfer to the printing data transfer direction after the time-out period lapses.
As the standard of data transmission between the computer and the printer, there have been known a compatibility mode, a nibble mode, a byte mode, an ECP mode and an EPP mode. When the computer and the printer are connected in parallel, the compatibility mode is generally used in the case of one-way communication which is a conventional system. In order to realize two-way communication, the nibble mode is employed as a basic system. That is, when normal printing data are send to the printer from the computer, the printing data is transferred in the compatibility mode and when the computer requires status information on the printer, the status information is transferred from the printer to the computer in the nibble mode. Accordingly, during printing, the printing data and the status information are alternately transferred at predetermined intervals.
In the case of the fixed format, communication of a predetermined amount of data is constantly required even if change in status of the stencil printer is small, which results in low utilization of data. In the case of the variable format, the last time-out period is vain, which also results in low utilization of data when switching between transfer of the status information and that of the printing data is frequent.
SUMMARY OF THE INVENTION
In view of the foregoing observations and description, the primary object of the present invention is to provide an interface system which can efficiently transfer the status information.
In accordance with the present invention, there is provided an interface system which transmits printing data from a computer to a stencil printer and transmits status information on the stencil printer to the computer, characterized by having
a previously-transmitted status information memory which stores status information on the stencil printer which has been previously transmitted to the computer,
an updated status information receiving means which receives from the stencil printer updated status information on the stencil printer,
a status difference information generation means which generates status difference information which represents difference of the updated status information from the status information which has been previously transmitted to the computer, and
a status difference information transmitting means which transmits the status difference information to the computer on request from the computer.
The term “status information” used here means information on whether the stencil printer is in a stopped state, in action, or in an error state.
It is preferred that the interface system of the present invention be provided with a means for transmitting the updated status information in place of the status difference information when so requested by the computer.
Further it is preferred that the status difference information generation means be provided with a means which separates the updated status information into fixed status information which represents the fixed status of the stencil printer and variable status information which represents the variable status of the stencil printer, and generates the status difference information on the basis of the variable status information.
In accordance with the present invention, since only the status difference information which represents difference of the updated status information from the previously transmitted status information is transmitted to the computer, the amount of data to be transmitted is minimized and the status information on the stencil printer can be efficiently transmitted to the computer. Accordingly, even in the case where the amount of printing data is large as in a host base printer driver, the status of the stencil printer can be watched without deteriorating data transmission efficiency. Especially when the status information is transmitted to the computer from the interface system interrupting transfer of the printing data from the computer to the interface in a nibble mode of IEEE 1284, where data are transmitted 4 bits by 4 bits, the status information can be more efficiently transmitted by reducing the amount of data in the manner described above. Further, in the case where a plurality of computers are connected to the interface system through a LAN or the data are transferred via a modem, data traffic can be reduced and data transfer efficiency is improved by reducing the amount of data of status information.
When the interface system of the present invention is provided with a means for transmitting the updated status information in place of the status difference information when so requested by the computer, the whole updated status information can be transmitted to the computer in situations where the previously transmitted status information has been lost from the computer, e.g., by disconnecting the computer from the power source or a different computer is connected to the interface system.
Further when the status difference information is generated on the basis of the variable status information by separating the updated status information into the fixed status information and the variable status information, the communication load between the interface system and the stencil printer can be lightened, whereby the status information can be transferred more efficiently.
REFERENCES:
patent: 5214772 (1993-05-01), Weinberger et al.
patent: 5502543 (1996-03-01), Aboujaoude
patent: 5561501 (1996-10-01), Honma
patent: 5798738 (1998-08-01), Yamada
Hilten John S.
Nolan, Jr. Charles H.
Peabody LLP Nixon
Riso Kagaku Corporation
Studebaker Donald R.
LandOfFree
Interface system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Interface system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Interface system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2480932