Abstract:
A printing apparatus receives print data described by a printer language from a host computer and prints an image of characters and figures on the basis of the print data. The printing apparatus includes a bit map image developing circuit for receiving print data from the host computer through a bidirectional interface and developing the print data into a bit map image, a bit map image transmitter for transmitting the bit map image of one page developed by the bit map image developing circuit to the host computer through the bidirectional interface, an input unit for inputting instruction information to instruct a printing process from the host computer through the bidirectional interface, and a print controller for printing the bit map image on the basis of the instruction information received through the input unit.

Description:
This application is a continuation of application Ser. No. 08/281,176, filed Jul. 27, 1994, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a printing apparatus and, more particularly, to a printing apparatus for receiving data which is described by a printer language from a host computer and for printing an image such as characters, figures, or the like on the basis of the data. 
     2. Description of the Related Art 
     Hitherto, a printing apparatus generally individually has resources such as print fonts or the like which are actually used in the printing. The printing apparatus receives the data described by a printer language from a host computer and develops the data by using the above resources and prints it. 
     In case of printing data by using a printer as mentioned above, however, there is a problem such that the resource such as a font or the like which is used by the host computer in order to display data on a screen does not exist in the resources which are used in the printer or, even the case of a resource of the same name, the print result which the user expects cannot be obtained because of a reason such that the implement of the source slightly differs in dependence on the supplying side. 
     Namely, as shown in a conceptual diagram of FIG. 1, in the case where print data  101  described by the printer language is formed on a host computer  103  having a resource  102  and the formed print data  101  is printed by a printer  105  having a resource  104 , when the font designated by the print data  101  does not exist in the printer  105 , there is a case where a display result  106  on the screen of the host computer  103  does not coincide with a print result  107  of the printer  105 . Reference numeral  108  denotes an interface cable to connect the host computer  103  and the printer  105 . The interface cable  108 , however, cannot bidirectionally transmit and receive information. 
     It is an object of the present invention to provide a printing apparatus and printing method, in which it is possible to prevent a print result different from that expected by the user from being obtained and an undesirable printing can be suppressed in consideration of the above problems. 
     According to the present invention, the above object is accomplished by a printing apparatus comprising: bit map image developing means for receiving print data from a host computer through a bidirectional interface and developing it into a bit map image; bit map image transmitting means for transmitting the bit map image developed by the bit map image developing means to the host computer through the bidirectional interface; input means for inputting instruction information to instruct a printing process through the bidirectional interface; and print control means for printing the bit map image on the basis of the instruction information received through the input means. 
     According to the present invention, in consideration of the problem such that there is a case where the result which is obtained on the screen of the host computer differs from the result from the printing apparatus, the printer transmits the bit map image developed from the print data to the host computer, the bit map image is displayed on the host computer, the user is allowed to judge whether the output result from the printer can be admitted as a result expected by the user or not, and only the output result which can be admitted is printed. Therefore, it is possible to prevent that the print result different from the result expected by the user is obtained, and the undesirable printing can be suppressed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a conceptual diagram showing a conventional processing function which includes a case where an image on a host computer differs from an image that is derived from a printer; 
     FIG. 2 is a conceptual diagram showing a function which is realized by the present invention; 
     FIG. 3 is a flowchart showing a processing procedure in the case where a bit map image which is obtained by developing print data in the first embodiment of the present invention can be stored in a RAM of a printer; 
     FIG. 4 is a flowchart showing a processing procedure in the case where a bit map image of one page in the second embodiment of the present invention can be stored in a RAM of a printer; and 
     FIG. 5 is a flowchart showing a processing procedure in the case where a bit map image of one page in the third embodiment of the present invention cannot be stored in a RAM of a printer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be described in detail hereinbelow with reference to the drawings. 
     FIG. 2 shows a schematic construction around a printer of an embodiment of the invention. 
     In FIG. 2, reference numeral  201  denotes a RAM installed in the printer  105  of the embodiment. A formed bit map image or the like is stored into the RAM  201 . Reference numeral  202  denotes a bit map image developed on the RAM  201  on the basis of a character code or control code which was input from the host computer  103  denotes through a bidirectional interface  208 ;  203  a screen display of the bit map image  202  on the host computer;  204  denotes a program which is installed into the printer  105  and is executed by a CPU  206 ; and  205  denotes a program which is installed into the host computer  103  and is executed by a CPU  207 . 
     Programs shown in flowcharts of FIGS. 3,  4 , and  5  are executed by the CPU  206  or  207 . 
     FIG. 3 shows an operating procedure of the first embodiment of the invention. The operation of the embodiment of the invention will now be described with reference to FIGS. 2 and 3. First, on the basis of an instruction of the user, the CPU  207  executes an application program or the like in the host computer  103  and forms the print data  101  described by a printer language (step  301  in FIG.  3 ). By an instruction of the user, the CPU  207  transmits the formed print data  101  (for example, comprising a character code or control code or image data) to the printer  105  (step  302 ). The CPU  206  in the printer  105  develops the bit map image  202  from the received print data  101  onto the RAM  201  (step  303 ). 
     After the bit map image  202  is developed, the CPU  206  in the printer  105  halts the printing process of the printer  105  and transmits the bit map image  202  to the host computer  103  through the bidirectional interface  208  (step  304 ). The CPU  207  in the host computer  103  receives the bit map image  202  by the program  205  and displays the received bit map image  202  onto the screen  203  (step  305 ). 
     The CPU  207  in the host computer  103  discriminates whether the bit map image  202  displayed on the screen of the host computer  103  for the user should be printed or not, for instance, whether instruction information to instruct the continuation of the printing operation has been input or not (step  306 ). If YES, the continuation of the printing operation of the printer  105  is instructed to the CPU  206  of the printer  105  and the CPU  206  of the printer  105  continues the printing operation (step  307 ). 
     When it is judged in step S 306  that the instruction information to instruct the continuation of the printing has not been inputted, the CPU  207  of the host computer  103  instructs the initialization of the printer  105  to the CPU  206  of the printer  105  through the bidirectional interface  208 . The CPU  206  of the printer  105  initializes the printer  105  (step  308 ). The instruction information to instruct the continuation of the printing mentioned above is input by a method whereby the user selects a print continuation icon (not shown) on the display screen of the host computer  103  by using, for example, a keyboard or a pointing device (not shown). 
     [Another Embodiment 1] 
     An example in which the print data  101  is converted into the bit map image in a lump has been shown in the first embodiment of the invention. An embodiment (second embodiment) in the case where the RAM  201  for bit map image of one page or more has initially been installed in the printer  105  will now be described with reference to a flowchart of FIG.  4 . 
     The CPU  207  in the host computer  103  forms print data described by the printer language by using an application program or the like (step  401  in FIG.  4 ). In response to an instruction of the user, the CPU  207  transmits the formed print data  101  to the printer  105  through the bidirectional interface  208  (step  402 ). The CPU  206  in the printer  105  checks to see if the print data to be printed exists in a reception buffer (RAM) (not shown) or not (step  403 ). If it doesn&#39;t exist, the processing routine is finished. If it exists, one page of the print data  101  received is developed into the bit map image on the RAM  201  (step  404 ). 
     The CPU  206  in the printer  105  halts the printing process of the printer  105  and transmits the bit map image  202  to the host computer  103  through the bidirectional interface  208  (step  405 ). The CPU  207  in the host computer  103  receives the bit map image  202  and displays the received bit map image  202  onto the display screen  203  (step  406 ). 
     The CPU  207  of the host computer  103  allows the user to confirm whether the bit map image  202  displayed on the screen of the host computer  103  should be printed or not by, for instance, discriminating whether the instruction information has been input or not (step  407 ). When it is confirmed that the printing is executed, the CPU  206  of the printer  105  instructs to resume the printing process of the printer  105  through the bidirectional interface  208  and the CPU  206  of the printer  105  instructs the printing of one page of data (step  408 ). 
     When it is confirmed that the printing is not executed, the CPU  207  of the host computer  103  instructs the cancellation of the bit map image  202  to the CPU  206  of the printer  105  through the bidirectional interface  208  and the CPU  206  cancels the bit map image  202  (step  409 ). 
     The printer  105  restarts the processes from the foregoing step  403 . 
     The above processes are repeated until the received print data  101  is consumed. 
     [Another Embodiment 2] 
     An embodiment (third embodiment) in the case where only the RAM  201  for bit map image of an amount less than one page has been installed in the printer  105  will now be described in detail with reference to a flowchart of FIG.  5 . 
     The CPU  207  in the host computer  103  forms the print data described by the printer language  101  by using the application program or the like (step  501  in FIG.  5 ). In response to an instruction of the user, the CPU  207  transmits the formed print data  101  to the printer  105  through the bidirectional interface  208  (step  502 ). The CPU  206  in the printer  105  checks to see if the print data  101  to be printed exists in the reception buffer (RAM) (not shown) or not (step  503 ). If the print data  101  doesn&#39;t exist, the processing routine is finished. If it exists, a part of one page of the print data  101  received is developed into the bit map image on the RAM  201  (step  504 ). 
     The CPU  206  in the printer  105  halts the printing process of the printer  105  and transmits the bit map image  202  to the host computer  103  through the bidirectional interface  208  (step  505 ). The CPU  207  in the host computer  103  receives the bit map image  202  and displays the received bit map image  202  onto the screen  203  (step  506 ). 
     The CPU  206  in the printer  105  discriminates whether the bit map image of one page has been transmitted to the host computer  103  or not (step  507 ). When an amount of transmitted bit map is less than one page, the processes from step  504  are repeated until the bit map image of one page has been transmitted. 
     When the data of one page is transmitted to the host computer  103  and the bit map image of one page is displayed on the screen of the host computer  103 , the CPU  207  in the host computer  103  allows the user to judge whether the bit map image  202  displayed on the screen of the host computer  103  should be printed or not by, for example, checking whether the instruction information has been input or not (step  508 ). When it is confirmed that the printing is executed, the data of the relevant page of the print data  101  from the host computer  103  or the bit map image displayed on the screen of the host computer  103  is transmitted to the CPU  206  of the printer  105  through the bidirectional interface  208  and the CPU  206  instruct the printing of one page (step  509 ). 
     When it is confirmed that the printing is not performed, the CPU  206  of the printer  105  cancels the bit map image  202  (step  510 ). 
     The processes are again started from step  503  mentioned above. 
     The above processes are repeated until the received print data  101  is consumed. 
     In the description of each of the above embodiments, it is assumed that the memory location to develop the print data  101  is the RAM. However, a similar effect can be also obviously obtained even by using a secondary memory such as hard disc drive (HDD). 
     According to the invention as described above, before the print result itself which is obtained from the printer is printed, a confirmation by the user is performed on the host computer and, after that, the print image is printed. Therefore, it is possible to prevent that the print result different from that expected by the user is obtained. Undesirable printing can thus be avoided.