Abstract:
An image processing apparatus for receiving a plurality of data groups, each of which belongs to a different command system of an external apparatus. A data analyzer is included in each command system. A data receiver receives the data from the external apparatus, and a judgment is made as to whether each of the data groups received by the data receiver contains the data analyzer corresponding to the command system of the corresponding data group. A print controller bypasses a data group of a command system judged not to include the data analyzer, and printing is disabled for that data group.

Description:
This application is a continuation of application Ser. No. 07/818,357 filed Jan. 9, 1992, abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image processing apparatus capable of processing a plurality of command systems, and more particularly to an image processing apparatus suitable for use with a printer which prints out a plurality of data, each of which is described in a different page description language. 
     2. Related Background Art 
     In a conventional printer of this type, a first control program and a second control program, different from the first control program, are selectively used. The first control program is mounted fixedly on the printer main body. The second control program is stored in a storage medium which can be removably mounted on the printer main body. 
     The second control program is generated by emulating a command system (page description language) of another printer. Therefore, application programs of the other printer can be used by a host computer without modifying them. 
     In this manner, for example, a high quality command system of the first control program and a conventional command system of low quality can be used compatibly with each other. 
     In printing data of the second command system supported by the second control program, the host computer first sends a control program selecting command, and then sends data from the second command system to the printer. 
     However, since the printer is structured to removably mount a storage medium, it may occur that a storage medium storing a third control program supporting a third command system is mounted, and the third command system not supported by the host computer. 
     In such a case, since the third command system contains some part different from the command system of print data sent form the host computer, printing is disabled. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to solve the above problem. 
     It is another object of the present invention to provide an image processing apparatus capable of processing a data group of various command systems preset to the apparatus. 
     According to the present invention, there is provided an image processing apparatus for receiving a plurality of data groups each belonging to a different command system from an external apparatus and processing the data groups, comprising: 
     data receiving means for receiving the data groups from the external apparatus; 
     data analyzing means provided in correspondence with each command system; 
     means for judging if each of the data groups received by the data receiving means contains the data analyzing means corresponding to the command system of the data group; and 
     print controlling means for passing by a data group of a command system judged by the judging means as not containing the data analyzing means, without printing the data group. 
     It is another object of the present invention to provide an image processing apparatus capable of processing a plurality of command systems (page description languages) without cumbersome operations by a user. 
     It is a further object of the present invention to provide an image processing apparatus capable of preventing waste operation when data of a command system unable to be processed by the apparatus is inputted. 
     The other objects, advantages and effects of the present invention will become more apparent from the following detailed description and claims when read in conjunction with the accompanying drawings, 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing an embodiment of the present invention, 
     FIG. 2 is a schematic diagram showing the memory structure of a program cartridge according to the embodiment of FIG. 1. 
     FIG. 3 is a schematic diagram showing the format of a command for instructing to shift a main body side program to a program cartridge side program according to the embodiment of FIG. 1. 
     FIG. 4 is a schematic diagram showing the format of a command for instructing to shift a program cartridge side program to the main body side program according to the embodiment of FIG. 1. 
     FIG. 5 is a schematic diagram showing the data structure of a main body shift command table according to the embodiment of FIG. 1. 
     FIG. 6 is a flow chart showing the operation of the main body side program according to the embodiment of FIG. 1. 
     FIG. 7 is a flow chart showing the operation of a program cartridge side program. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be described with reference to the accompanying drawings. 
     FIG. 1 is a block diagram showing the structure of a laser beam printer according to an embodiment of the present invention. A controller 100 of the printer includes a CPU 102 for controlling the printer, and an interface 103 for receiving data from a host computer 101 via an input signal line S11. The interface 103 informs CPU 102 of data reception. 
     A ROM 104 stores a first control program (refer to FIG. 6) of a first printer command system (page description language), control information (refer to FIG. 5 for example) used by the first control program, and character dot patterns. 
     A RAM 105 is used by the control program, and includes a work area for the control program andan image memory area for storing a bit map image of one page of data. 
     A display panel 106 is constructed of a seven segment LED to display various operation states under control of the CPU 102. 
     An image signal generator 107 converts an one page bit map image data developed on the image memory area of RAM 105 into an image signal. The generator 107 outputs an image signal 22 to a printing mechanism 109 synchronously with a synchronizing signal S21 sent from the printing mechanism 109. 
     An output interface 108 interfaces between the controller 100 and the printing mechanism 109. 
     The printing mechanism 109 receives an image signal from the controller 100, and executes a series of laser beam printer operations, including supply of a recording sheet, turn-on/off of a laser beam, transfer of an image to a recording sheet, and fixation of a transferred image. 
     An interface 110 interfaces between a program cartridge 112 connected to a cartridge connector 111 and the controller 100. CPU 102 accesses a ROM of the program cartridge 112 via the interface 110, and senses a presence/absence of the cartridge 112. 
     The program cartridge 112 has a ROM circuit board on which are mounted a ROM and its peripheral circuit elements. The cartridge 112 stores a second control program of a printer command system (hereinafter called a second command system) different from the first control program stored in ROM 104. The second control program controls the laser beam printer, in the same manner as the first control program. 
     The program cartridge 112 is structured so as to be removably mounted on the cartridge connector 111 of the controller 100. The program cartridge 112 can be replaced with another program cartridge 112 (not shown) which stores a third control program. 
     The first control program in ROM 104 is called hereinafter a program A, and the second control program in the program cartridge 112 is called a program Bj (j=1, 2, . . . : a symbol &#34;B&#34; is used for collectively indicating the second control programs). 
     FIG. 2 is a schematic diagram showing the memory structure of the program B stored in the program cartridge 112. 
     In FIG. 2, an area 201 is a program identification area for storing a program ID number. Each ID number of the control program is stored in this area, having four bytes from the start address &#34;0&#34;. 
     Another area 202 is a program area for storing object codes of the program B, starting from an address &#34;4&#34; of ROM. 
     FIG. 3 is a schematic diagram showing the format of a program command 300 in the program A stored in the ROM 104. This program command 300 instructs to shift from the program A to the program B in the program cartridge 112. 
     This command format is of a so-called escape sequence command system. Defined in this command are a control code ESC (1B H) 301 representing the start of the command, an ID number 302 of the shifted program B, and a command terminator P 303 (also used as a command discriminator). 
     When control is shifted from the program A to the program B in the program cartridge 112, the host computer sends the command 300. The program A analyzes this command 300 to pass the control to the program B in the program cartridge 112. 
     This command 300 is called hereinafter a cartridge shift command. 
     FIG. 4 is a schematic diagram showing the format of a program command 400 of the program Bj stored in the program cartridge 112. This program command 400 instructs to shift from the program Bj to the program A stored in ROM 104. 
     The function of this program command 400 is similar to that of the program command 300 of FIG. 3 for instructing to shift from the program A to the program B. The format matches its command system. In this example, the format is of a text type. A character code sequence 401. &#34;@%&#34; is a command start discriminator followed by a command character sequence 402. 
     The command character sequence &#34;GOTONATIVE&#34; instructs to shift from the program B to the program A. When the program Bj detects this command 400, it passes the control to the program A. Similar to the cartridge shift command 300, this command 400 is sent by the host computer 101. 
     This command 400 is called hereinafter a main body shift command. Such a main body shift command 400 is prepared for each program Bj matching its command system. 
     FIG. 5 is a schematic diagram showing the data structure of a main body shift command table stored in ROM 104. 
     As described above, this printer can use various program cartridges 112, each of which stores different control programs, by mounting each selected program cartridge on the side of the controller 100. The main body shift command table 500 stores main body shift commands matching the command systems of each of these programs B, with table 500 including areas 501, 502 and 503. The area 501 is a program ID number area for storing the ID number of each program B. The area 502 is a command length area for setting the length 1 of the main body shift command. The area 503 is a code area for storing a code sequence of the main body shift command. Sets of these areas are provided, equal in number to the number of available program cartridges, to constitute the table 500. 
     For example, a set 504 is constructed of an ID number area of a program Bj, a command length area 502, and a main body shift command code area 503. 
     Next, the control operation of switching between the control program A on the main body side and the control program Bj on the program cartridge side will be described. 
     FIG. 6 is a flow chart showing the operation of the program A. An initializing operation for the program A is first executed (S601). The input interface 103 is checked, and data from the host computer is waited for (S602). When data is received, it is taken from the input interface 103 and analyzed (S603). The input data is discriminated as to whether it is a command or a character code. If the input data conforms with the cartridge shift command 300 shown in FIG. 3 (S604), the flow advances to step S608 to enter a program switching process to be described later. If the input data is discriminated as a character code at step S604, a corresponding character dot pattern is read from ROM 104 (S605) and developed on the image memory area of RAM 105 to generate an image at an output page. The operations from step S602 to step S605 are repeated until data analysis of one page is completed (S606). When an image of one page has been generated, information in the image memory area of RAM 105 is sent to the image signal generator 107(S607) to print the image at the printing mechanism 109. Then, the flow returns to step S602 to process information for the next page. 
     If the cartridge shift command 300 is detected at step S604, it is determined whether or not the program cartridge 112 is mounted (S608). If the cartridge 112 is mounted, it is determined whether or not the program ID number 302 indicated by the cartridge shift command 300 is the same as the program ID number set in the program identification area 201 at the cartridge 112 (S609). If they coincide with each other, it means that the designated program Bj exists so that the flow jumps to the top of the program area 202 at the cartridge 112 to pass the control to the program Bj (i.e., jump to step S701 to be described later) (S610). 
     If it is determined at step S608 that the program cartridge 112 is not mounted, or if the program ID numbers are not coincident with each other at step S609, this means that the program Bj designated by the host computer 101 does not exist. In this case, the flow advances to step S611. 
     An alarm mark is displayed as an error indication on the display panel 106 (S611) to thereby notify an operator of an absence of the designated program Bj. Character dot patterns representative of the character sequence of an error message are developed on the image memory area of RAM 105 to print out the error message at the printing mechanism 109 (S612). 
     After the host computer 101 sends the cartridge shift command to the printer, it transfers a data group for the program Bj. 
     Using the program ID number 302 of the cartridge shift command 300 detected at step S604, the main body shift command table 500 is searched to read the code sequence in the corresponding main body shift command area 503 (S613). In this example, the set 504 corresponding to the program Bj is selected to read the main body shift command code sequence &#34;@% GOTONATIVE&#34;. 
     Thereafter, data from the host computer 101 is waited for in a manner similar to step S602 (S614). The operation at step S614 continues without printing the received data until the main body shift command code sequence &#34;@% GOTONATIVE&#34; is received (S615). 
     After the main body shift command code sequence is detected, the host computer 101 transfers a data group for the program A. Therefore, the alarm mark on the display panel 106 is deleted (S616), and the flow returns to step S602 to further continue the data processing. 
     FIG. 7 is a flow chart showing the operation of the program Bj at the program cartridge 112. 
     When control is passed to the program BJ from step S610 for the program A, an initializing operation for the program Bj is executed to reset the state of the controller 100 used by the program A (S701). 
     Next, data from the host computer 101 is waited for (S702). The inputted data is analyzed (S703) to discriminate between a command and a character code which match the command system supported by the program Bj. 
     If the inputted data is the same as the main body shift command 400 shown in FIG. 4 (S704), the control is passed to the program A in ROM 104 (i.e., to step S601) (S708). 
     If the inputted data is a character code at step S704, a corresponding character pattern is developed on the image memory area of RAM 104 (S705). The operations from step S702 to step S705 are repeated until an image of one complete page is generated (S706). Upon generation of an image of one page, the image information is sent to the image signal generator 107 to print one page image at the printing mechanism 109 (S707). 
     The flow returns to step S702 to further process the next page. 
     As described above, the main body shift command table stores the format of a shift command to the first control program, the shift command having been defined by the second control program. Therefore, even if a designated second control program does not exist, a data group used for the second control program sent from the host computer can be passed by without printing it, until the first control program is obtained. As a result, it is possible to avoid waste prints without temporarily stopping the printer. 
     In the above embodiment, only one cartridge connector 111 is used. A plurality of connectors may be used to mount a plurality of program cartridges each having a different control program. In such a case, the first control program selects one of the control programs having a program ID number the same as that in the cartridge shift command. In this manner, the host computer can automatically select one of a plurality of control programs, allowing to print various data, each having a different command system. 
     Furthermore, in the above embodiment, one program cartridge has one control program. A plurality of program identification areas 201 and program areas 202 as shown in FIG. 2 may be provided. Similar to a plurality of cartridges, the host computer can automatically select one of a plurality of control programs. 
     Still further, in the above embodiments, the first control program is stored in ROM 104 of the printer. The present invention is not limited only to such a case. All control programs including the first control program may be of a cartridge type connected to a plurality of cartridge connectors. In such a case, each control program defines a shift command of FIG. 3 to allow the operations at steps S608 to S611 shown in FIG. 6. 
     In the above embodiment, the end of the data which is passed by without printing it because the second control program does not exist, is determined by searching the main body shift command table in ROM 104. The present invention is not limited only to such a case. For example, the main body shift command table may be down-loaded from the host computer into a RAM, e.g., at the time immediately after power is turned on. 
     A plurality of main body shift command tables may be stored in ROM cartridges to be detachably connected to cartridge connectors. 
     By preparing a plurality of main body shift command tables, it is possible to readily deal with an addition of a program cartridge supporting a new command system. 
     In the above embodiment, switching between control programs is performed by using two commands including the cartridge shift command and main body shift command. The present invention is not limited only to such a case. For example, the characteristic of a command system may be derived from a data sequence sent from the host computer, to automatically select the corresponding control program. 
     In such a case, provided on the printer side is a table for deriving a characteristic of a command system corresponding to the main body shift command from table the or an analysis program. Using this table or program, a transition position between command systems is checked. After detecting the transition position, if the control program for the command system to be transferred does not exist on the main body side or as a program cartridge, the data is passed by without printing it until the next transition position is detected upon deriving the characteristic of the command system. A user can deal with various command system data without considering switching between control programs. 
     In the printer of the above embodiment which can mount a plurality of control programs, data which does not match a command type is passed by without printing it. The present invention is not limited only to such a case. For example, also in a printer supporting only one control program and one command system, a shift command may be checked or the characteristic of a command type may be derived, to pass by data other than that of a command system supported by the printer. 
     According to the present invention, of various data each having a different command system, data having a command system not supported by the printer can be passed by without printing it. Therefore, it is possible to avoid waste prints and allow continuous operation of the printer even if there is improper data. 
     The present invention is not limited to the above embodiment, but various modifications are possible which fall within the scope of the appended claims.