Patent Publication Number: US-7212756-B2

Title: Image forming apparatus with extraordinary state detection

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an image forming apparatus which performs image forming form image data; for example, a printer, a facsimile, a copying machine, an image processing apparatus with image presenting section etc. 
   2. Description of the Related Art 
   An example of image forming apparatus is a printer. A printer performs printing the image data on a paper. There are various kinds of printers such as printers of electro-photography, thermal transcribing, wire dotting etc. 
     FIG. 11  shows a configuration of a conventional printer adopting electro-photography. 
   As shown in  FIG. 11 , a host device  1  is connected via interface  2  to system bus  3 . And, processor  4 , program ROM  5 , working memory  6 , font ROM  7 , image memory  8 , print engine interface  9  are connected to the system bus  3 . Further, a print engine as image forming section  20  is connected to the print engine interface  9 . 
   An image processing section  10  is made up of elements from the interface  2  to the print engine interface  9 . The image forming section  20  comprises controlling unit  21  and print mechanism  22 . Moreover, fan  23  is equipped to the print mechanism  22 . 
   The host device  1  is what makes up data for printing, such as computer, word processor, image reader etc. And, the interface  2  is a circuit which comprises RS232C interface or parallel interface etc. The processor  4  performs the overall control of the printer as an image forming apparatus. The control program which is executed in the processor  4  is installed in the program ROM  5 . 
   Moreover, the working memory  6  is a memory for memorizing and managing data which is received or sending via the interface  2 . And, the font ROM  7  is a memory which is used for transforming character code or other code received via the interface  2 , into bitmap font data for printing. 
   Moreover, the image memory  8  comprises random access memory for containing for example one page of printing data which is an image data edited by the processor  4 . The print engine  20  is a device which performs printing on papers according to the printing data contained in the image memory  8 . It comprises paper carrier or electro-photographic process device etc. 
   The print engine interface  9  is an interface circuit for reading out printing data  9   a  from image memory  8  according to the indication of processor  4  to transfer it to print engine  20 , or receiving print control signal  9   b  put out from print engine  20  to send it to processor  4  etc. 
   In the printer mentioned above, control command or character code, graphic code, bitmap image data etc. are temporarily contained in working memory  6  if necessary. And, it is transformed into image data for printing according to the control of processor  4 , to be compiled on image memory  8 . 
   As mentioned above, when characters are printed, the bitmap font contained in font memory  7  is used. But, in the occasion when the bitmap data corresponding to the character to be printed is not contained in font memory  7 , the bitmap data is obtained from DLL (Down Line Loading) font of the host device  1 . And, this data is registered in a certain area of DLL memory  6   a  in working memory  6 . 
   Moreover, in the occasion when high resolution printing is performed the image memory  8  needs large capacity fit for the high resolution. Therefore, a method for realizing high resolution with comparatively small capacity of memory at low cost is offered by the applicant of the present invention (JP 63-146764, 1988). 
     FIG. 12  shows an example of the side view of the printer as image forming apparatus in  FIG. 11 . 
   In  FIG. 12 , charging roller  101  supplies electric charge to the surface of photo-sensitive drum  102  which turns to the direction indicated by an arrow shown in the drawing. The photo-sensitive drum  102  comprises a cylinder made of metal such as aluminum etc. with photo-sensitive material painted on its surface. And, it is supplied with electric charge uniformly over its surface by the charging roller  101 . Then, its surface is partially lighted by exposer  103  comprised of an array of LED etc. And, only electric charge on the lighted part of surface is taken away, so as to form image to be printed. 
   On the other hand, toner feeding roller  105  feeds the developing roller  106  with the charged toner preserved in toner tank  104 . And, the charged toner is transferred from the surface of developing roller  106  to non-charged part of the surface of photo-sensitive drum  102 , by the pulling force of static electricity caused by the difference of electric potential between toner and photo-sensitive drum  102 . 
   And, transfer roller  107  is given a certain electric potential which is able to attract the charged toner from the photo-sensitive drum  102  to transfer roller  107 . Meanwhile, paper feeding roller  108  feeds a paper between the photo-sensitive drum  102  and transfer roller  107 . The paper feeding roller  108  confronts backup roller  110 , so as to put a paper between them. The paper feeding roller  108  is driven by a motor not shown in the drawings. And, the paper is carried from right hand side to left hand side in the drawings as the paper feeding roller turns. 
   Thus, the paper is carried to be put between photo-sensitive drum  102  and transfer roller  107 . Then, the charged toner is transferred from the surface of photo-sensitive drum  102  to the surface of paper by the attraction force of static electricity caused from the electric potential of transfer roller  107 . Here, the toner is not fixed to the paper. 
   And, the paper is carried to be put between fixing roller  111  and fixing backup roller  112 . Then, the plastic material in toner is momentarily melted by the fixing roller  111  which is heated up to high temperature, so as to fix toner to the paper. 
   By the way, there are, for example, two heat emitting elements in the printer housing. One is the fixing roller  111  which fixes toner on papers with proper heat. The other is the processor  4  which processes making up of image data to be printed. 
   As for a printer, in general, cooling means like fan  23  is necessary to control heat for fixing toner. On the other hand, such cooling means is also necessary to control temperature of processor  4 , because the processor  4  operates at proper temperature. And, effective cooling means is needed to keep the proper temperature, as process speed increases because printing speed becomes faster and resolution becomes higher in today&#39;s printer. Therefore, it is important to cool both of the two heat emitting elements sufficiently. 
   Meanwhile, the same cooling means for control fixing toner is used for controlling data processing, because it costs much to equip another cooling means. Therefore, two or three routes for leading wind are formed in the printer housing from the same cooling means to each of heat emitting elements. 
   However, there is a problem to be solved in this occasion. That is, the routes for wind can change according to the state of printer housing, for example, opening of the cover of housing or jamming of paper in the housing. Therefore, either of heat emitting elements cannot be cooled sufficiently. 
   And, not only printer but also other image forming apparatus such as image recording apparatus including facsimile, copying machine etc. or image presenting apparatus including display etc. has the same problem. 
   SUMMARY OF THE INVENTION 
   Therefore, the present invention adopts next configurations aiming at solving the problem mentioned above. 
   The first configuration comprises an image processing section for processing image data inputted from an external apparatus, an image forming section for forming image from the image data processed by the image processing section, a state detecting means to detect the state of said image forming apparatus, a state judging means to judge whether said image forming apparatus is in ordinary state or extraordinary state according to the state of said image forming apparatus and an operating mode changing means to change the operating mode of said image processing section into the other operating mode of different electricity consumption. 
   The second configuration comprises an image processing section for processing image data inputted from an external apparatus, an image forming section for forming image from the image data processed by the image processing section, a state detecting means to detect the state of said image forming apparatus, a state judging means to judge whether said image forming apparatus is in ordinary state or extraordinary state according to the state of said image forming apparatus and an operating frequency changing means to change the operating frequency of said image processing section into different operating frequency. 
   The last configuration comprises a memory, an access controlling means to control access to data in said memory, an image processing section for processing image data inputted from an external apparatus, an image forming section for forming image from the image data processed by the image processing section, a state detecting means to detect the state of said image forming apparatus, a state judging means to judge whether said image forming apparatus is in ordinary state or extraordinary state according to the state of said image forming apparatus and an access frequency changing means to change the access frequency for said memory into different access frequency. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing a configuration of an image forming apparatus according to Embodiment 1. 
       FIG. 2  shows a side view of the image forming apparatus of  FIG. 1  when its cover is shut. 
       FIG. 3  shows a plan view of the image forming apparatus of  FIG. 1  when its cover is shut. 
       FIG. 4  shows a side view of the image forming apparatus of  FIG. 1  when its cover is open. 
       FIG. 5  shows a plan view of the image forming apparatus of  FIG. 1  when its cover is open. 
       FIG. 6  is a flowchart showing the operation of the image forming apparatus of  FIG. 1 . 
       FIG. 7  is a block diagram showing a configuration of an image forming apparatus according to Embodiment 2. 
       FIG. 8  is a flowchart showing the operation of the image forming apparatus of  FIG. 7 . 
       FIG. 9  is a block diagram showing a configuration of an image forming apparatus according to Embodiment 3. 
       FIG. 10  is a flowchart showing the operation of the image forming apparatus of  FIG. 9 . 
       FIG. 11  is a block diagram showing a configuration of a conventional image forming apparatus. 
       FIG. 12  shows a plan view of a general printer by electro-photography. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereafter, preferred embodiments of the present invention are described referring to the drawings. 
   &lt;Embodiment 1&gt; 
     FIG. 1  shows a configuration of a printer as an example of image forming apparatus according to Embodiment 1 of present invention. 
   As shown in  FIG. 1 , a host device  1  is connected via interface  2  to system bus  3 . And, processor  4 , program ROM  5 , working memory  6 , font ROM  7 , image memory  8 , print engine interface  9  are connected to the system bus  3 . Further, a print engine as image forming section  20  is connected to the print engine interface  9 . Moreover, the processor  4  has a function of changing electricity consumption mode into low mode. So, it has a low electricity consumption changing register  41  for realizing this function. 
   An image processing section  10  is made up of elements from the interface  2  to the print engine interface  9 . The image forming section  20  comprises controlling unit  21  and print mechanism  22 . Moreover, fan  23  is equipped to the print mechanism  22 . And, state detecting means  24  is equipped in the image forming section  20 , so as to detect the physical state of the image forming section  20 . For example, the state detecting means  24  comprises a sensor for detecting the cover of the printer housing opening or shutting. 
   The host device is what makes up data for printing, such as computer, word processor, image reader etc. And, the interface  2  is a circuit which comprises RS232C interface or parallel interface etc. 
   The processor  4  performs the overall control of the printer as an image forming apparatus. The control program which is executed in the processor  4  is installed in the program ROM  5 . And, the low electricity consumption changing register  41  which is equipped in the processor  4  indicates “ON” or “OFF”, so as to represent the low electricity consumption mode of halting circuits in the processor  4  which is not used or represent the ordinary mode of functioning all circuits in the processor  4 . 
   The control program executed in processor  4  includes state judging means  44  and operating mode changing means  45 . The former detects the cover of printer open or shut according to the signal from state detecting means  24 . The latter controls the power supply to the processor  4  according to the representation in the low electricity consumption changing register  41 . 
   Moreover, the working memory  6  is a memory for memorizing and managing data which is received or sending via the interface  2 . And, the font ROM  7  is a memory which is used for transforming character code or other code received via the interface  2 , into bitmap font data for printing. 
   Moreover, the image memory  8  comprises random access memory for containing for example one page of printing data which is an image data edited by the processor  4 . The print engine  20  is a device which performs printing on papers according to the printing data contained in the image memory  8 . It comprises paper carrier or electro-photographic process device etc. 
   The print engine interface  9  is an interface circuit for reading out printing data  9   a  from image memory  8  according to the indication of processor  4  to transfer it to print engine  20 , or receiving print control signal  9   b  put out from print engine  20  to send it to processor  4  etc. 
   In the printer mentioned above, control command or character code, graphic code, bitmap image data etc. are temporarily contained in working memory  6  if necessary. And, it is transformed into image data for printing according to the control of processor  4 , to be compiled on image memory  8 . 
     FIG. 2  shows the side view of the printer as image forming apparatus when the cover is shut. 
   In  FIG. 2 , charging roller  101  supplies electric charge to the surface of photo-sensitive drum  102 . The photo-sensitive drum  102  comprises a cylinder made of metal such as aluminum etc. with photo-sensitive material painted on its surface. And, it is supplied with electric charge uniformly over its surface by the charging roller  101 . Then, its surface is partially lighted by exposer  103  comprised of an array of LED etc. And, only electric charge on the lighted part of surface is taken away, so as to form image to be printed. 
   On the other hand, toner feeding roller  105  feeds the developing roller  106  with the charged toner preserved in toner tank  104 . And, the charged toner is transferred from the surface of developing roller  106  to non-charged part of the surface of photo-sensitive drum  102 , by the pulling force of static electricity caused by the difference of electric potential between toner and photo-sensitive drum  102 . 
   And, transfer roller  107  is given a certain electric potential which is able to attract the charged toner from the photo-sensitive drum  102  to transfer roller  107 . Meanwhile, paper feeding roller  108  feeds a paper between the photo-sensitive drum  102  and transfer roller  107 . The paper feeding roller  108  confronts backup roller  110 , so as to put a paper between them. The paper feeding roller  108  is driven by a motor not shown in the drawings. And, the paper is carried from right hand side to left hand side in the drawings as the paper feeding roller turns. 
   Thus, the paper is carried to be put between photo-sensitive drum  102  and transfer roller  107 . Then, the charged toner is transferred from the surface of photo-sensitive drum  102  to the surface of paper by the attraction force of static electricity caused from the electric potential of transfer roller  107 . Here, the toner is not fixed to the paper. 
   And, the paper is carried to be put between fixing roller  111  and fixing backup roller  112 . Then, the plastic material in toner is momentarily melted by the fixing roller  111  which is heated up to high temperature, so as to fix toner to the paper. Here, the temperature of fixing roller  111  must be controlled to keep the best temperature for fixing. 
   Therefore, intake fan  23  and exhaust fan  23 ′ are equipped. The intake fan  23  is located near one of the lower corner of the printer housing. And, the exhaust fan  23 ′ is located near the opposite corner on the diagonal of housing. Thus, cooling wind is blown up from intake fan  23  to exhaust fan  23 ′ through the ventilation pass of route B shown in  FIG. 2 . 
     FIG. 3  shows a plan view of the printer housing. 
   As shown in  FIG. 3 , there are three ventilation passes of route A, B and C in the printer housing. 
   The route A runs through the image processing section  10  which is equipped between the side frame  121  and the side cover of the printer housing. Thus, the hot air heated by the image processing section  10  is let out through route A. 
   The route B runs below the transfer roller  107  and runs above the fixing roller  111 . Thus, the hot air heated by the fixing roller  111  is let out through route B. 
   The route C runs through the controlling unit  21  of image forming section  20  which is equipped between side frame  122  and side cover of printer housing. Thus, the hot air heated by the controlling unit  21  is let out through route C. 
     FIG. 4  shows the side view of the printer when the cover is open. And,  FIG. 5  shows the plan view of the printer when the cover is open. 
   As shown in  FIG. 4 , almost all the air let in by the intake fan  23  is let out from the upper opening when the cover is open. So, as shown in  FIG. 5 , only small quantity of wind is let out from the exhaust fan  23 ′. And, little wind blows in each of route A′ and route C′. Therefore, little cooling effect is given to each of the image processing section  10  and the controlling unit  21 . 
   &lt;Operation of Embodiment 1&gt; 
   The operation of the printer according to Embodiment 1 of present invention is described referring to the flowchart shown in  FIG. 6 . In addition, in description to be mentioned below, opening of the cover of printer housing is adopted as a parameter for predicting cooling ability drop. But, it can also be predicted by other parameters. An example of this is paper jam in printer which disturbs the wind blowing in the ventilation pass of printer. 
   When the power-supplying switch of printer is turned on, at first, the state judging means  44  judges whether the cover of printer is opened or not. Unless the cover is opened, it keeps watching the cover opening or shutting (step S 31 ). 
   If the cover of printer is opened by the user own or some other person for some reason, the low electricity consumption mode is set to the low electricity consumption changing register  41  of processor  4  by the operating mode changing means  45  (step S 32 ). By this mode setting, processor  4  enters in the low electricity consumption mode. And, the power supply to the circuits which are not operating in processor  4  is shut off. As a result, heating of processor  4  is lowered. While the cover is opening, the low electricity consumption changing register is kept “ON”. And, the low electricity consumption mode of processor  4  is kept. As a result, the temperature of processor  4  goes down. 
   If the state judging means  44  detects the cover getting shut by the user or somebody (step S 33 ), the operating mode changing means  45  changes the low electricity consumption mode register  41  into “OFF”, so as to get processor  4  returned from the low electricity consumption mode to the ordinary mode (step S 34 ). 
   In addition, as shown in  FIG. 2 , in the occasion when the paper jammed between the transfer roller  107  and fixing roller  111 , it crosses the route B. So, the cooling wind blows below the fixing backup roller  112 . As a result, cooling effect to the fixing roller  111  which has a heater, becomes weak. In such occasion like this, similar effect is obtained by adopting present invention. 
   Moreover, the present invention is not applied to printer but also applied to facsimile or copying machine which cover are able to be opened or shut. Further, it is also applied to image presenting apparatus which is equipped with a image presenting section instead of the image recording section. 
   &lt;Effect of Embodiment 1&gt; 
   As mentioned above, according to Embodiment 1, the invention can provide a printer which is able to keep down the temperature of it easily and at low cost without equipping extra fan to the image processing section even if the printer should go into an extraordinary state such as cover opening or paper jam in the printer, because it can keep the temperature rise under control with the low electricity consumption mode of processor  4  when the cooling ability drop occurred from insufficient flow of wind to the cooling subject owing to the internal wind pass change in the printer which cover was opened or paper jammed. 
   &lt;Embodiment 2&gt; 
     FIG. 7  shows a configuration of a printer as an example of image forming apparatus according to Embodiment 2 of present invention. 
   As shown in  FIG. 7 , a host device  1  is connected via interface  2  to system bus  3 . And, processor  4 , program ROM  5 , working memory  6 , font ROM  7 , image memory  8 , print engine interface  9  are connected to the system bus  3 . Further, a print engine as image forming section  20  is connected to the print engine interface  9 . Moreover, an oscillator (OSC)  42  is connected to the processor  4 . This oscillator  42  is able to change its clock frequency. 
   An image processing section  10  is made up of elements from the interface  2  to the print engine interface  9 . The image forming section  20  comprises controlling unit  21  and print mechanism  22 . Moreover, fan  23  is equipped to the print mechanism  22 , so as to cool the print mechanism  22  and the image processing section  10 . And, state detecting means  24  is equipped in the image forming section  20 , so as to detect the physical state of the image forming section  20 . For example, the state detecting means  24  comprises a sensor for detecting the cover of the printer housing opening or shutting. 
   The host device  1  is what makes up data for printing, such as computer, word processor, image reader etc. And, the interface  2  is a circuit which comprises RS232C interface or parallel interface etc. 
   The processor  4  performs the overall control of the printer as an image forming apparatus. The control program which is executed in the processor  4  is installed in the program ROM  5 . And, the oscillator  42  connected to the processor  4  changes its clock frequency according to the indication of processor  4 . 
   The control program executed in processor  4  includes state judging means  44  and operating frequency changing means  46 . The former detects the cover of printer open or shut according to the signal from state detecting means  24 . The latter indicates the clock frequency of the oscillator  42  according to the judgement of state judging means  44 . 
   Moreover the working memory  6  is a memory for memorizing and managing data which is received or sending via the interface  2 . And, the font ROM  7  is a memory which is used for transforming character code or other code received via the interface  2 , into bitmap font data for printing. 
   Moreover, the image memory  8  comprises random access memory for containing for example one page of printing data which is an image data edited by the processor  4 . The print engine  20  is a device which performs printing on papers according to the printing data contained in the image memory  8 . It comprises paper carrier or electro-photographic process device etc. 
   The print engine interface  9  is an interface circuit for reading out printing data  9   a  from image memory  8  according to the indication of processor  4  to transfer it to print engine  20 , or receiving print control signal  9   b  put out from print engine  20  to send it to processor  4  etc. 
   In the printer mentioned above, control command or character code, graphic code, bitmap image data etc. are temporarily contained in working memory  6  if necessary. And, it is transformed into image data for printing according to the control of processor  4 , to be compiled on image memory  8 . 
   &lt;Operation of Embodiment 2&gt; 
   The operation of the printer according to Embodiment 2 of present invention is described referring to the flowchart shown in  FIG. 8 . In addition, in description to be mentioned below, opening of the cover of printer housing is adopted as a parameter for predicting cooling ability drop. But, it can also be predicted by other parameters. An example of this is paper jam in printer which disturbs the wind blowing in the ventilation pass of printer. 
   When the power-supplying switch of printer is turned on, at first, the state judging means  44  judges whether the cover of printer is opened or not. Unless the cover is opened, it keeps watching the cover opening or shutting (step S 51 ). 
   If the cover of printer is opened by the user own or some other person for some reason, the prescribed value n-Low set in advance at the oscillator  42  to slow down the operation speed of processor  4  is selected by the operating frequency changing means  46  (step S 52 ). By this selecting, processor  4  operates with low clock frequency. As a result, heating of processor  4  is lowered. While the cover is opening, the low clock frequency is kept. And, the slow operation of processor  4  is kept. As a result, the temperature of processor  4  goes down. 
   If the state judging means  44  detects the cover getting shut by the user or somebody (step S 53 ), the operating frequency changing means  46  changes the low clock frequency into the ordinary frequency, so as to get processor  4  returned from the slow operation to the ordinary operation (step S 54 ). 
   &lt;Effect of Embodiment 2&gt; 
   As mentioned above, according to Embodiment 2, the invention can provide a printer which is able to keep down the temperature of it easily and at low cost without equipping extra fan to the image processing section even if the printer should go into an extraordinary state such as cover opening or paper jam in the printer, because it can keep the temperature rise under control with the control of lowering operating frequency of processor  4  when the cooling ability drop occurred from insufficient flow of wind to the cooling subject owing to the internal wind pass change in the printer which cover was opened or paper jammed. 
   &lt;Embodiment 3&gt; 
   Although the basic configuration of the apparatus of Embodiment 3 is almost the same as Embodiment 1 or 2, a significant difference is that the processor  4  in the third embodiment has a cache memory. Additionally, the apparatus of the third embodiment does not have neither a means for changing into low electricity consumption mode nor a means for slowing down the operation speed of the processor  4 . 
     FIG. 9  shows a configuration of a printer as an example of image forming apparatus according to Embodiment 3 of present invention. 
   As shown in  FIG. 9 , a host device  1  is connected via interface  2  to system bus  3 . And, processor  4 , program ROM  5 , working memory  6 , font ROM  7 , image memory  8 , print engine interface  9  are connected to the system bus  3 . Further, a print engine as image forming section  20  is connected to the print engine interface  9 . Moreover, the processor  4  has a cache memory  43 . 
   An image processing section  10  is made up of elements from the interface  2  to the print engine interface  9 . The image forming section  20  comprises controlling unit  21  and print mechanism  22 . Moreover, fan  23  is equipped to the print mechanism  22 . And, state detecting means  24  is equipped in the image forming section  20 , so as to detect the physical state of the image forming section  20 . For example, the state detecting means  24  comprises a sensor for detecting the cover of the printer housing opening or shutting. 
   The host device  1  is what makes up data for printing, such as computer, word processor, image reader etc. And, the interface  2  is a circuit which comprises RS232C interface or parallel interface etc. 
   The processor  4  performs the overall control of the printer as an image forming apparatus. The control program which is executed in the processor  4  is installed in the program ROM  5 . A cache memory  43  is equipped in the processor  4 . The cache memory  43  memorizes the contents of other memories outside of the processor  4 , that is program memory  5 , working memory  6 , font memory  7  or image memory  8 , which have ever been accessed. Thus, the cache memory  43  enables access to the same contents rapidly. 
   The control program executed in processor  4  includes state judging means  44 , access controlling means  47  and access frequency changing means  48 . The first detects the cover of the printer open or shut according to the signal from the state detecting means  24 . The second controls access to data in the cache memory  43 . For example, it controls not getting access to the cache memory  43  but the other memory which contains original data, by flushing data in the cache memory  43 . The last controls access frequency to the cache memory  43 , for example, by flushing data in the cache memory  43 . Thus, the cache memory  43  is temporarily without access to the original data. So, by adopting cache flush, the access controlling means  47  and access frequency changing means  48  are embodied in the same means. 
   Moreover, the working memory  6  is a memory for memorizing and managing data which is received or sending via the interface  2 . And, the font ROM  7  is a memory which is used for transforming character code or other code received via the interface  2 , into bitmap font data for printing. 
   Moreover, the image memory  8  comprises random access memory for containing for example one page of printing data which is an image data edited by the processor  4 . The print engine  20  is a device which performs printing on papers according to the printing data contained in the image memory  8 . It comprises paper carrier or electro-photographic process device etc. 
   The print engine interface  9  is an interface circuit for reading out printing data  9   a  from image memory  8  according to the indication of processor  4  to transfer it to print engine  20 , or receiving print control signal  9   b  put out from print engine  20  to send it to processor  4  etc. 
   In the printer mentioned above, control command or character code, graphic code, bitmap image data etc. are temporarily contained in working memory  6  if necessary. And, it is transformed into image data for printing according to the control of processor  4 , to be compiled on image memory  8 . 
   &lt;Operation of Embodiment 3&gt; 
   The operation of the printer according to Embodiment 3 of present invention is described referring to the flowchart shown in  FIG. 10 . In addition, in description to be mentioned below, opening of the cover of printer housing is adopted as a parameter for predicting cooling ability drop. But, it can also be predicted by other parameters. An example of this is paper jam in printer which disturbs the wind blowing in the ventilation pass of printer. 
   When the power-supplying switch of printer is turned on, at first, the state judging means  44  judges whether the cover of printer is opened or not. Unless the cover is opened, it keeps watching the cover opening or shutting (step S 61 ). 
   If the cover of printer is opened by the user own or some other person, cache flush control is performed to clear away the contents of cache memory  43 , so as to miss the cache memory  43  (step S 62 ). By this setting, processor  4  is made not to hit the cache memory  43 . So, it becomes not to operate rapidly. And, the processor  4  has a long wait for access because it cannot hit the cache memory  43 . As a result, the operating frequency is relatively lowered. Then, the electricity consumption in processor  4  is lowered. And, at the same time, the temperature of processor  4  goes down. In addition, this cache flush control can be performed by either of cache memory&#39;s own function or processor&#39;s own writing function. 
   Next, the processor  4  has a wait of a prescribed time with timer&#39;s counting (step S 63 ). Thus, the cache flush is not performed for the prescribed time. These steps S 62 , S 63  and S 64  are repeated until the cover of printer is shut by the user or somebody. 
   If the state judging means  44  detects the cover getting shut by the user or somebody (step S 64 ), these steps S 62 , S 63  and S 64  are not repeated no longer, so as to get processor  4  returned from the low electricity consumption mode of cache flush to the ordinary mode. 
   &lt;Effect of Embodiment 3&gt; 
   As mentioned above, according to Embodiment 3, the invention can provide a printer which is able to avoid extraordinary temperature rise in it easily and at low cost without equipping extra fan or other costly cooling system to the image processing section even if the printer should go into an extraordinary state such as cover opening or paper jam in the printer, because it can keep the temperature rise under control with the cache flush in processor  4  which drops access frequency of processor  4  when the cooling ability drop occurred from insufficient flow of wind to the cooling subject owing to the internal wind pass change in the printer which cover was opened or paper jammed. 
   &lt;Other Embodiment&gt; 
   In each Embodiment mentioned above, described is a temperature controlling apparatus of detecting only one kind of extraordinary state of apparatus. That is either of the cover open state or paper jammed state etc. But, the present invention is not limited to this, it can also be embodied in apparatus which can detect more than two kinds of extraordinary state. For example, both of cover open state and paper jammed state are detected. And, two kinds of temperature control are performed about two kinds of state respectively; because changes of wind blowing pass in the apparatus are different between cover open and paper jam, and temperature rises are different. 
   Moreover, control of the processor  4  is described in each Embodiment mentioned above. But, the temperature control is also adopted to the other part of the image processing section  10  or the controlling unit  21  of image forming section  20 . And, the oscillator  42  in  FIG. 7  can be equipped inside of the processor  4 . Further, other elements than the processor  4  can be replaced by different form of elements which have similar function. And, the print engine as image forming section  20  can be replaced by other printing means than electro-photography means.