Patent Publication Number: US-6708005-B2

Title: Image forming apparatus and method of controlling memory thereof

Description:
FIELD OF THE INVENTION 
     This invention relates to an image forming apparatus into which a cartridge having a built-in memory is inserted, and to a method of controlling the memory. 
     BACKGROUND OF THE INVENTION 
     An image forming apparatus known in the art employs a non-volatile memory mounted on a replaceable unit for the purpose of improving the image quality of a copier or printer, or other device, and in order to perform accurate management of the lifetime of the replaceable unit. In an image forming apparatus of this kind, the connection between the non-volatile memory of the replaceable unit and the apparatus proper is achieved by a connector. However, since the signal to the non-volatile memory is very weak, a malfunction can occur even if there is only a slight imperfection in electrical contact within the connector. 
     Accordingly, in an effort to avoid faulty contact in the connector, an image forming apparatus in which a main body of the apparatus proper and the non-volatile memory are coupled electromagnetically has been proposed in the specification of Japanese Patent Application Laid-Open No. 11-338329. 
     More specifically, in a printer that employs an electrophotographic process, for example, a process cartridge (replaceable unit), which is obtained by integrating a photosensitive drum, a developing device and a toner accommodating compartment, or other device, is removably installed in the printer and is equipped with a non-contact IC memory unit for recording such information as the history of use and the process conditions, or other data. 
     In a case where information is recorded in the IC memory unit or information in the IC memory unit is updated, specified information is merely recorded in a designated memory area and, as a consequence, there is the possibility that items of related data will no longer be in conformity with each other. Accordingly, the IC memory unit is so arranged that items of data that are interrelated are rewritten automatically when information serving as the reference is recorded. Among these items of interrelated information, the information serving as the reference is referred to as higher-order information and the information that is rewritten in association with the higher-order information is referred to as lower-order information. 
     Consider a case where information (denoted by “NewCartridgeBit” below) indicating a cartridge that is brand new and information (denoted by “FirstInstallDate” below) indicating first date of use is registered in the IC memory unit. In this instance, the former is higher-order information and the latter is lower-order information. If the cartridge is a new cartridge, a NewCartridgeBit is set in the mounted IC memory unit and a date serving merely as an initial value is recorded as the FirstInstallDate. 
     If printing is executed upon installing the new cartridge in the printer, the NewCartridgeBit constituting the higher-order information is reset and, in association therewith, the date of print execution is recorded as the FirstInstallDate, which is the lower-order information. However, a printer control unit within the printer does not possess data indicative of the current date. In actuality, therefore, the FirstInstallDate is recorded in response to receipt of current-date data possessed by a controller that has been connected to the printer or by an external host computer that has been connected to the printer via this controller. 
     However, in a conventional printer in which the cartridge having the built-in memory is installed, the items of information that have been recorded in the memory of the cartridge will not necessarily be in harmony with each other. 
     For example, the above-mentioned printer often possesses a test-print function that enables the printing function to be checked in the development stage of the printer without connecting a controller that assists in data communication with, e.g., an external host computer. 
     When test printing is performed in the above-mentioned conventional printer, a new (unused) cartridge is installed in the printer. However, because a controller or host computer has not been connected to the printer, data indicative of the current date cannot be acquired in the printer control unit and, as a consequence, the FirstInstallDate cannot be recorded in the IC memory unit of the cartridge, and the NewCartridgeBit is merely reset. 
     The problem that arises in this case is that even if a controller is connected and printing is performed after the test print, the fact that the NewCartridgeBit will already have been reset means that nothing will be recorded for the FirstInstallDate, which is the lower-order information updated in association with the NewCartridgeBit. 
     Thus, if only the higher-order information of interrelated information within the IC memory unit of the above-described conventional printer is updated or if the lower-order information is not capable of being updated for some reason, then it will not be possible to subsequently update only the related lower-order information. Thus, the problem arises that the information that is recorded in the memory unit will be defective. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide an image forming apparatus, in which a cartridge with a built-in memory is installed, and a method of controlling the memory, wherein the apparatus is capable of maintaining the conformity between mutually related information that has been recorded in the memory within the cartridge. 
     In order to attain the above-described objects, an image forming apparatus of the present invention comprises a structure as follows. 
     An image forming apparatus from which a unit having a non-volatile memory for storing first and second information can be removed, comprises: update designation means for designating the updating of information stored in the non-volatile memory; and update means for updating the information, which has been recorded in the non-volatile memory, based upon a designation by the update designation means; wherein the update means updates the second information after the completion of updating of the first information in a case where the designation is to update the first information, and the update means updates the second information if the second information is a predetermined value, in a case where the designation is to update the second information. 
     In order to attain the above-described objects, a memory control method of the present invention comprises the steps as follows. 
     A memory control method in an image forming apparatus from which a unit having a non-volatile memory for storing first and second information can be removed, comprises: an update designation step of designating the updating of information stored in the nonvolatile memory; a first update step of updating the second information after a completion of updating of the first information in a case where it is designated to update the first information at the update designation step; and a second update step of updating the second information if the second information is a predetermined value, in a case where it is designated to update the second information at the update designation step. 
     Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and, together with the description, serve to explain the principles of the invention. 
     FIG. 1 is a diagram showing a schematic representation of a printer according to a first embodiment of the present invention; 
     FIG. 2 is a block diagram of the printer according to this embodiment; 
     FIG. 3 is a flowchart illustrating processing for updating higher-order information according to this embodiment; 
     FIG. 4 is a flowchart illustrating processing for updating lower-order information according to this embodiment; and 
     FIG. 5 is a flowchart illustrating processing for updating lower-order information according to a second embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will now be described in detail with reference to the drawings. 
     First Embodiment 
     [Structure of Apparatus] 
     Described first will be the structure of an electrophotographic printer (referred to simply as a “printer” below), which is one example of an image forming apparatus to which this embodiment is applied. The printer according to this embodiment is so adapted as to enable removable installation (replacement) of a process cartridge obtained by integrating a photosensitive drum, a developing device and a toner accommodating compartment, and/or other devices. The process cartridge is equipped with a non-contact IC memory unit for recording such information as the history of use and the process conditions, and/or other data. 
     FIG. 1 is a diagram useful in describing the general structure of the printer according to this embodiment. 
     As shown in FIG. 1, the printer includes a photosensitive drum  101  serving as a carrier for an electrostatic latent image. A charging roller  102  for uniformly charging the surface of the photosensitive drum  101  is provided above the photosensitive drum  101  in contact with the surface thereof. The charged surface of the photosensitive drum  101  downstream from the point of contact with the charging roller  102  in the direction of rotation is irradiated with a light beam  103  by light generating means. The light generating means includes a semiconductor laser  104  for emitting the light beam  103 , a scanner  105  that causes the light beam  103  to scan the surface of the photosensitive drum  101 , and an optical lens  106  for adjusting the light beam  103  so as to form a spot on the surface of the photosensitive drum  101 . An electrostatic latent image is formed on the surface of the photosensitive drum  101  owing to irradiation with the light beam  103  based upon the image data. 
     The electrostatic latent image is developed as a toner image on the photosensitive drum  101  by a developing unit  107  disposed so as to contact the photosensitive drum  101  at a point farther downstream, in the direction of rotation, of the point irradiated by the light beam  103 . The toner image is transferred to paper P, which serves as a transfer medium, by a transfer roller  108  disposed below the photosensitive drum  101  so as to oppose the same. Though the paper P is accommodated in a paper cassette  109  disposed in front of the photosensitive drum  101  (on the right-hand side of the photosensitive drum  101  in FIG.  1 ), the paper P can be fed manually if desired. A paper-feed roller  110  is disposed at the end of the paper cassette  109  and rotates to feed the paper P from the interior of the paper cassette  109  to a transport path. Disposed in the transport path between the paper-feed roller  110  and the transfer roller  108  is a registration roller  111  for correcting skew of the paper P and synchronizing formation of the image on the photosensitive drum  101  and transport of the paper P. Thus the paper P is fed to the above-mentioned transfer point at a predetermined timing. A paper-presence sensor  112  is disposed between the registration roller  111  and paper-feed roller  110  and is adapted to sense the absence or presence of the paper P. 
     The paper P to which the unfixed toner image has thus been transferred is transported to a fixing device in back of the photosensitive drum  101  (on the left-hand side of the photosensitive drum  101  in FIG.  1 ). The fixing device comprises a fixing roller  113  having an internal fixing heater (not shown), and a pressurizing roller  114  placed so as to come into pressured contact with the fixing roller  113 . The paper P transported from the transfer point is heated while being subjected to pressure at the pressurizing point between the fixing roller  113  and pressurizing roller  114 , whereby the unfixed toner image on the paper P is fixed to the paper P. A paper ejection sensor  115  for checking that the paper P has been ejected from the pressurizing point is disposed in back of the pressurizing point. Ejection rollers  116  are provided in back of the paper ejection sensor  115  and eject, to the exterior of the machine, the printed paper P to which the toner image has been fixed. 
     Reference will now be had to the block diagram of FIG. 2 to describe the structure of the electrophotographic printer having the mechanism illustrated in FIG.  1 . 
     As shown in FIG. 2, a host computer  201 , which is disposed externally of the electrophotographic printer, sends parallel or serial image code data that has been created by a user operation to a controller  203  via a communication line  202 . 
     The controller  203  expands the image code data sent from the host computer  201 , converts the data to image information to be sent to the printer, issues a command to a printer control unit  204 , reads internal data from the printer control unit  204  as status data and sends the printer control unit  204  a print start request and a preliminary paper-feed request. Further, an operation panel  205  that allows the user to set the printer to various modes (and to set the margin of an image area, and/or other parameters) is connected to the printer control unit  204 . 
     It should be noted that the controller  203  may reside within the printer or within the host computer  201 . 
     In order to control the timing for starting and stopping each component in the mechanism shown in FIG.  1  and in order to read input information from each of the sensors, the printer control unit  204  is connected to a transport drive unit  206 , a high-voltage drive unit  207 , an optical drive unit  208 , a fixing heater control unit  209 , and a sensor input unit  210 . Each of these drive units will now be described. 
     On the basis of commands from the printer control unit  204 , the transport drive unit  206  drives and halts motor  211  and various rollers  212  and the high-voltage drive unit  207  drives and halts the charging unit  213 , the development unit  214 , and the transfer unit  215 . 
     On the basis of commands from the printer control unit  204 , the optical drive unit  208  drives and halts the laser  104  and scanner  105  and the fixing heater control unit  209  drives and halts the fixing heater  216 . 
     The sensor input unit  210  reads information from the paper-presence sensor  112  and the paper ejection sensor  115  and supplies this information to the printer control unit  204 . 
     The control operation in the printer having the structure set forth above will now be described. 
     First, the printer attains a state in which it awaits a print signal from the controller  203 . 
     If a print signal has not yet been received, the printer determines whether a preliminary paper-feed request has been issued by the controller  203 . If such a request has been received, then the motor  211  is driven into operation and paper feed is started. The printer then checks to see whether the paper P has arrived at the position of the paper-presence sensor  112 . When the leading edge of the paper P is sensed by the paper-presence sensor  112 , the printer halts the paper-feed operation upon elapse of a predetermined period of time. At this moment the motor  211  is stopped and the printer waits for a print signal. 
     If a print signal is received from the controller  203 , the printer starts up the scanner  105  and the high voltage system when the motor  211  is driven into operation again. When the scanner motor (not shown) reaches a stipulated rotation, the paper-presence sensor  112  checks for the absence/presence of the paper P because the paper P has already been fed preliminarily. If the paper P is not present at the paper-presence sensor  112  at this time, processing (jam processing, and/or other processing) for dealing with an abnormal situation is executed. If the paper-presence sensor  112  senses the presence of the paper P, a vertical-synchronization request signal is output to the controller  203 . 
     Upon receiving the vertical-synchronization request signal, the controller  203  supplies a vertical synchronization signal to the printer control unit  204 . When the printer control unit  204  receives the vertical synchronization signal, the printer control unit  204  enables writing of an image onto the photosensitive drum  101  and drives the registration roller  111  into rotation. Upon the elapse of a predetermined period of time from detection of the trailing edge of the paper P by the paper ejection sensor  115 , the operation of the high-voltage drive unit  207  and the scanner motor is stopped and the rotation of the motors in the roller drive system is halted, thereby terminating print processing. 
     In the electrophotographic printer described here, use is made of a process cartridge, which is obtained by integrating the photosensitive drum  101 , the developing unit  107  and the toner compartment shown in FIG.  1 . The process cartridge is capable of being removably installed in the printer proper. Furthermore, the process cartridge is equipped with a non-contact IC memory unit  219  shown in FIG.  2 . By storing print condition data such as the number of sheets printed and the length of current application time in the IC memory unit  219 , the optimum process conditions (high-voltage conditions, and/or other conditions) can be found for every print job. 
     The electrophotographic printer is equipped with a memory-communication control board  220  for communication with the non-contact IC memory unit  219 . The memory communication control board  220  has a memory communication control unit  220   a , a modulator/demodulator circuit  220   b , a transmit circuit  220   c  and a receive circuit  220   d . The transmit circuit  220   c  includes a resonance circuit  220   e.    
     The modulator/demodulator circuit  220   b  is connected to an antenna coil  221  via the transmit circuit  220   c  and the receive circuit  220   d , the modulator/demodulator circuit  220   b  is connected to the memory communication control unit  220   a , and the memory communication control unit  220   a  is connected to the printer control unit  204 . The sending and receiving of data between the printer control unit  204  and non-contact IC memory unit  219  is performed over the above path. 
     The non-contact IC memory unit  219  has an IC  219   a  and an antenna coil  219   b  for producing electromagnetic induction. As a result of electromagnetic induction produced by the antenna coil  219   b , the IC  219   a  acquires electric power and communication data from the printer proper that is sent and received via the memory-communication control board  220 . 
     The IC  219   a  incorporates a demodulator circuit for demodulating modulated data at the time of data reception and a modulator circuit for modulating demodulated data and sending the modulated data to the antenna coil  219   b  at the time of data transmission. These circuits make it possible to send and receive data to and from the printer proper. 
     The printer control unit  204  communicates with the memory communication control unit  220   a  on the memory communication control board  220  using the serial communication function of a microcontroller. 
     An example of information recorded in the non-contact IC memory unit  219  mounted in the process cartridge is information indicating the number of sheets printed, the length of current application time, the first date of use and whether the cartridge is a new cartridge, information indicating the status of use of the printer such as the amount of remaining toner, a warning of little remaining toner, and a warning of toner depletion, and information indicating printing process conditions such as the sensitivity of the photosensitive drum and a timing threshold value for changing over the value of a charging current. Furthermore, the non-contact IC memory unit  219  has a non-volatile memory. When the power supply of the printer proper is turned off, therefore, the contents recorded in the memory will be preserved for use the next time the power supply is turned on. 
     [Updating of Data in Non-contact IC Memory Unit  219 ] 
     In a case where information of interest is to be recorded or updated in the non-contact IC memory unit  219 , there is the possibility that interrelated items of data will no longer be in conformity with each other if specified information is merely recorded in a designated memory area. This can lead to certain contradictions. For example, information indicating that the cartridge is a new cartridge may be set despite the e fact that the number of printing sheets is not “0”, or the date of last use may be earlier than the date of first use. 
     In order to avoid these contradictions, the interrelated items of information are updated automatically when reference information is recorded. Among these items of interrelated information, the reference information is referred to as higher-order information and the information that is updated in association with the higher-order information is referred to as lower-order information. 
     Consider a case where information (denoted by “NewCartridgeBit” below) indicating a cartridge that is brand new (unused) and information (denoted by “FirstInstallDate” below) indicating first date of use of the cartridge is registered in the IC memory unit  219 . In this instance the higher-order information is the NewCartridgeBit and the lower-order information is the FirstInstallDate. If the cartridge is a new cartridge, the NewCartridgeBit will have been placed in the set state in the mounted IC memory unit  219  and a date serving merely as an initial value will have been recorded as the FirstInstallDate. 
     If printing is executed upon installing the new cartridge in the printer, the state of the NewCartridgeBit is reset and the date of print execution should be recorded as the FirstInstallDate. The printer control unit  204 , however, does not possess date data. Here the printer control unit  204  can record the FirstInstallDate by accepting date data, which is possessed by the controller  203  or host computer  201 , via communication between the controller  203  and the printer control unit  204 . 
     However, as pointed out in the example of the prior art described earlier, the printer of this embodiment also is equipped with a test-print function that enables the printing function to be checked even in a state in which the controller  203  is not connected. Accordingly, if a new cartridge is installed and test printing is carried out, the fact that the controller  203  and host computer  201  have not been connected to the printer means that the FirstInstallDate cannot be recorded in the non-contact IC memory unit  219  and only the NewCartridgeBit is placed in the reset state. 
     Accordingly, in this embodiment when printing is performed upon connecting the controller  203  following a test printing, the FirstInstallDate, which is the lower-order information, is recorded independently in suitable fashion, in a case where the NewCartridgeBit, which is the higher-order information, has already been reset. Control for updating related information within the non-contact IC memory unit  219  according to this embodiment will now be described. 
     In the example described below, the NewCartridgeBit serving as the higher-order information and the FirstInstallDate serving as the lower-order information will be the items of interrelated information recorded in the non-contact IC memory unit  219 . That is, it is assumed that the NewCartridgeBit has been placed in the set state in the non-volatile memory within the non-contact IC memory unit  219  mounted in a new cartridge and that date information serving a simple initial value has been recorded as the FirstInstallDate in the non-volatile memory. 
     This embodiment is characterized in that the initial value of the FirstInstallDate serving as the lower-order information is not made “0” but is made a value (a predetermined date or null (0) which must not be set) that cannot possibly be set during usage of the image forming apparatus because it is possible to be written as “0” when an error (e.g., the memory writing operation is halted due to power OFF) or during writing data into the IC memory unit. 
     [Higher-order Information Update Processing (Relationship Update Processing)] 
     First, reference will be had to the flowchart of FIG. 3 to describe processing for associating and updating related information within the non-contact IC memory unit  219 , namely processing for a case where a command to rewrite the higher-order information has been received. 
     If a command to rewrite related higher-order information (NewCartridgeBit) has been received by the memory communication control unit  220   a  from the printer control unit  204  at step S 31 , control proceeds to step S 32 . Here the memory communication control unit  220   a  first determines whether the NewCartridgeBit is an initial value (in this case the set state “1”). If the bit is not the initial value, control proceeds to step S 37  without a rewrite being executed. Here error processing is executed and the process ends. On the other hand, if it is found at step S 32  that the NewCartridgeBit is the initial value “1”, control proceeds to step S 33 , where the NewCartridgeBit is reset (to state “0”). Then, at step S 34 , it is determined whether the FirstInstallDate is the initial value (a predetermined date or null which must not be set). If it is found that the FirstInstallDate is not the initial value, control proceeds to step S 37 , where a rewrite error is sent back. If the FirstInstallDate is the initial value, however, then control proceeds to step S 35 . Here time information given by the rewrite command is written as the FirstInstallDate. The operation is then ended normally (step S 36 ). 
     Thus, the rewriting of the NewCartridgeBit, which is the higher-order information, is accompanied also by the rewriting of the FirstInstallDate serving as the lower-order information. 
     [Lower-order Information Update Processing] 
     Reference will be had to the flowchart of FIG. 4 to describe the characterizing feature of this embodiment, namely processing for updating the lower-order information, i.e., processing for a case where a command to rewrite the lower-order information has been received. 
     If a command to rewrite the FirstInstallDate, which is the lower-order information, has been received by the memory communication control unit  220   a  from the printer control unit  204  at step S 41 , the control proceeds to step S 42 . Here the memory communication control unit  220   a  first determines whether the NewCartridgeBit, which is the related higher-order information, is an initial value (i.e., whether it is in the set state). If the bit is not the initial value, control proceeds to step S 43 , where it is determined whether the FirstInstallDate serving as the lower-order information is the initial value. If it is found at step S 43  that the FirstInstallDate is the initial value, then control proceeds to step S 44 . Here the specified date information is written to the memory and processing is ended normally (S 45 ). On the other hand, if it is found at step S 43  that the FirstInstallDate is not the initial value, then it is construed that a rewrite has already been performed and, hence, control proceeds to step S 46 . Here processing abends without a rewrite command being received. Further, if it is found at step S 42  that the NewCartridgeBit serving as the higher-order information is the initial value, control proceeds to step S 46 . Since it would be unnatural for a rewrite command to be generated solely with respect to the FirstInstallDate, which is the lower-order information, processing abends without such a command being received. 
     In accordance with the first embodiment, as described above, it is possible to update only the lower-order information of items of interrelated information, which have been recorded in the non-contact IC memory unit  219 , based upon control exercised by the memory communication control unit  220   a . As a result, it is possible to maintain the conformity between items of interrelated information. 
     Further, a value that cannot be taken on in ordinary processing is adopted as the initial value of the lower-order information. As a result, if an error of some kind occurs, not only in the lower-order information, but also in the content of the related higher-order information, this can be detected in highly precise fashion. 
     Second Embodiment 
     A second embodiment of the present invention will now be described. 
     As the structure and operation of the printer in the second embodiment are similar to those of the first embodiment set forth above, these need not be described again. In the second embodiment, also a value that cannot be taken on in ordinary processing is adopted as the initial value of lower-order information recorded in the non-contact IC memory unit  219 , and processing for updating related information, i.e., the operation in response to the command to rewrite the NewCartridgeBit serving as the higher-order information, is similar to that illustrated in the flowchart of FIG. 5 in the first embodiment. 
     [Lower-order Information Update Processing] 
     FIG. 5 is a flowchart illustrating processing according to a second embodiment in a case where a command to rewrite lower-order information has been received. 
     If a command to rewrite the FirstInstallDate, which is the lower-order information, has been received from the printer control unit  204  at step S 51 , the memory communication control unit  220   a  determines whether the NewCartridgeBit, which is the related higher-order information, is an initial value (the set state “1”) at step S 52 . If the NewCartridgeBit is not the initial value, control proceeds to step S 53 , where it is determined whether the FirstInstallDate is the initial value. If it is found at step S 53  that the FirstInstallDate is the initial value, then control proceeds to step S 54 . Here the specified date information is written to memory and processing is ended normally (step S 55 ). On the other hand, if it is found at step S 53  that the FirstInstallDate is not the initial value, then it is construed that a rewrite has already been performed and, hence, processing abends without a rewrite command being received (S 57 ). 
     If it is found at step S 52  that the NewCartridgeBit serving as the higher-order information is the initial value, control proceeds to step S 56 . Here the NewCartridgeBit is rewritten to the reset value “0” after which control proceeds to step S 53 , where it is determined whether the FirstInstallDate serving as the lower-order information is the initial value. Thereafter, in the manner described above, the specified time information is written to the memory and processing ends normally (S 54 , S 55 ) if the FirstInstallDate is the initial value, or processing abends (S 57 ) if the FirstInstallDate is not the initial value. 
     In accordance with the second embodiment, as described above, if an update command is issued solely with regard to lower-order information of items of interrelated information that have been recorded in the non-contact IC memory unit  219 , even the related higher order information can be updated as necessary. As a result, it is possible to maintain the conformity between items of interrelated information to an even greater extent than in the first embodiment. 
     [Other Embodiment] 
     In the first and second embodiments, an arrangement in which the printer control unit  204  and the memory-communication control board  220  are in dependent of each other is described. However, it is also possible to incorporate the memory-communication control board  220  within the printer control unit  204 . In accordance with such an arrangement, communication between the printer control unit  204  and memory-communication control board  220  can be made unnecessary. As a result, it is possible to lower the cost of the microcontroller used in the memory communication control unit  220   a  and to eliminate a delay in operation ascribable to communication between the printer control unit  204  and memory communication control unit  220   a.    
     The present invention can be applied to a system constituted by a plurality of devices (e.g., a host computer, interface, reader, printer, or other device) or to an apparatus comprising a single device (e.g., a copier or facsimile machine, or another device). 
     Furthermore, it goes without saying that the object of the invention is attained also by supplying a storage medium (or recording medium) storing the program codes of the software for performing the functions of the foregoing embodiments to a system or an apparatus, reading the program codes with a computer (e.g., a CPU or MPU) of the system or apparatus from the storage medium, and then executing the program codes. In this case, the program codes per se read from the storage medium implement the functions of the above embodiments and the storage medium storing the program codes constitutes the invention. Furthermore, besides the case where the aforesaid functions according to the embodiments are implemented by executing the program codes read by a computer, it goes without saying that the present invention covers a case where an operating system or the like running on the computer performs a part of or the entire process in accordance with the designation of program codes and implements the functions according to the embodiment . 
     It goes without saying that the present invention further covers a case where, after the program codes read from the storage medium are written in a function expansion card inserted into the computer or in a memory provided in a function expansion unit connected to the computer, a CPU or the like contained in the function expansion card or the function expansion unit performs a part of or the entire process in accordance with the designation of program codes and implements the function of the above embodiment. 
     The present invention is not limited to the above embodiments and various changes and modifications can be made within the spirit and scope of the present invention. 
     Therefore, to apprise the public of the scope of the present invention, the following claims are made.