Abstract:
An image forming apparatus having a reading unit which reads image information on an original, a first compression unit which compresses the image information into compressed image information, a first encoding unit which encodes the compressed image information, an interface unit which acquires printing information in a page description language from exterior, a generating unit which generates printing image information on the basis of the printing information, a second compression unit which compresses the printing image information into compressed printing image information, a second encoding unit which encodes the compressed printing image information, a decoding expansion unit which decodes and expands the encoded compressed image information and the encoded compressed printing image information, and a forming unit which forms an image onto a recording medium on the basis of the image information and the printing image information which have been decoded and expanded.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Recently, there exist digital multifunction devices having a copying function, a printer function, a facsimile function, and the like. In such a digital multifunction device, there are two or more areas generating image data. For example, at the time of copying, an image is inputted from a scanner of the device itself. Further, at the time of printing, an image described in a page description language is transmitted via an external interface from a personal computer at the exterior. The multifunction device develops the page description language into image data at the interior thereof. The image data is temporarily stored in a storage device in the multifunction device, for example, a hard disk or the like. At the time of printing, the image data is read out of the hard disk, and printed.  
         [0002]     Accompanying a rise in the need for improved data security in recent years, among the digital multifunction devices, a multifunction device which encodes and stores image data has appeared. In Jpn. Pat. Appln. KOKAI Publication No. 6-303440, there is disclosed a copier with an encoding function, and there has been shown a technique in which image information of a document or a drawing to stored is stored in a storage means, and at that time, the image information is encoded in order to improve the security, and is decoded at the time of using thereof.  
         [0003]     However, with respect to the multifunction devices in which image data is encoded and handled, for example, there can be considered a multifunction device in which both of image information from a scanner and a page description language (PDL) from a personal computer connected thereto are handled, and when the both compete with one another, there is the problem that a sufficient processing speed cannot be obtained because one processing is delayed if the other processing is given priority.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     One embodiment of the image forming apparatus is an image forming apparatus having a reading unit which reads image information on an original, a first compression unit which compresses the image information read by the reading unit into compressed image information, a first encoding unit which encodes the compressed image information, an interface unit which acquires printing information in a page description language from the exterior, a generating unit which generates printing image information on the basis of the printing information, a second compression unit which compresses the printing image information into compressed printing image information, a second encoding unit which encodes the compressed printing image information, a decoding expansion unit which decodes and expands the encoded compressed image information and compressed printing image information, and a forming unit which forms an image onto a recording medium on the basis of the image information and the printing image information which have been decoded and expanded by the decoding expansion unit. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0005]      FIG. 1  is a block diagram showing one example of an electrical configuration of an image forming apparatus.  
         [0006]      FIG. 2  is a cross sectional view showing one example of a mechanical configuration of the image forming apparatus.  
         [0007]      FIG. 3  is a flowchart showing one example of image processing of the image forming apparatus.  
         [0008]      FIG. 4  is a flowchart showing another example of image processing of the image forming apparatus.  
         [0009]      FIG. 5  is a flowchart showing even another example of image processing of the image forming apparatus.  
         [0010]      FIG. 6  is a flowchart showing other example of image processing of the image forming apparatus. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     Hereinafter, an image forming apparatus such as a multifunction digital copier will be described in detail with reference to the drawings.  
         [0000]     &lt;Image Forming Apparatus&gt; 
         [0000]     (Electrical Configuration)  
         [0012]     First, an electrical configuration of the image forming apparatus will be described with reference to the drawings.  FIG. 1  is a block diagram showing one example of the electrical configuration of the image forming apparatus. The image forming apparatus has a CPU  101  and a system controller  102  which are a control unit, a main memory  103  connected thereto by a data bus, and a compression accelerator  104  for handling printing image information based on a page description language (PDL). The compression accelerator  104  includes at least a second expansion circuit, a second compression circuit, a second encoding circuit, and a second decoding circuit. Further, an external I/F  107  such as Ether, MAC, USB2.0, and IEEE1284, a FAX-I/F  115 , a FAX board  116 , an IDE-I/F108, and an HDD  109  are connected via a PCI bus to the system controller  102 .  
         [0013]     Further, the image forming apparatus has an operation panel  110  connected to a system bus, for overall operational control, a scanner unit  111  for reading an original image, and an image processing circuit  112  connected thereto, for carrying out image processing of the read image, an image memory controller  105  for handling the original image information read from the scanner unit  111 , an image memory  106  connected thereto, an image processing circuit  113  for carrying out image processing on the image information from the image memory controller  105 , and a printer unit  114  for carrying out image formation on the basis of the image information from the image processing circuit  113 . In addition, the image memory controller  105  includes at least a first encoding circuit, a first decoding circuit, a first compression circuit, and a first expansion circuit.  
         [0014]     Here, it is preferable from the standpoint of improving the security that the image memory controller  105  including at least the first encoding circuit, the first decoding circuit, the first compression circuit, and the first expansion circuit is provided so as to be integrated in one LSI chip. In the same way, it is preferable from the standpoint of improving the security that the compression accelerator  104  including at least the second expansion circuit, the second compression circuit, the second encoding circuit, and the second decoding circuit is provided so as to be integrated in one LSI chip. However, the present invention is not limited thereto.  
         [0015]     Further, it is preferable that the image memory controller  105  and the compression accelerator  104  respectively have functions of controlling memories such as the image memory  106 , and the main memory  103 . However, the present invention is not limited thereto.  
         [0016]     Because the image forming apparatus has such an electrical configuration, a copying system image produced by a scanner, and a printer system image provided in PDL or the like can be processed in encoding circuits, or the like, respectively independent of one another. Therefore, even when a copying operation and a a printing operation are simultaneously requested, data can be encoded and stored in a hard disk without an increase in processing time being brought about.  
         [0000]     (Mechanical Configuration)  
         [0017]      FIG. 2  is a structural view for explanation of an internal structure of a color printing control unit. This image forming apparatus  1  is composed of a color scanner unit  4  serving as an image reading unit, an image forming unit (process unit)  5  for forming an output image, a printer unit  6 , an automatic document feeder (hereinafter, ADF)  7 , and the operating panel  80  which will be described later, etc.  
         [0018]     The scanner unit  4  has the ADF  7  at the top portion thereof, and there is provided a transparent glass document platen  8  which is disposed so as to face the ADF  7  in a state of being closed, and on which a document is set. Below the document platen  8 , an exposure lamp  25  for illuminating the document placed on the document platen  8 , and a first mirror  26  for concentrating light from the exposure lamp  25  on the document and refracting the reflected light from the document, for example, to the left direction with respect to the drawing, are fixed to a first carriage  27 .  
         [0019]     The first carriage  27  is disposed so as to be movable in parallel with the document platen  8 , and is made to move reciprocally below the document platen  8  by a scanning motor (not shown) via a toothed belt (not shown) or the like.  
         [0020]     Further, below the document platen  8 , a second carriage  28  which is movable in parallel with the document platen  8  is disposed. Second and third mirrors  30  and  31  which successively reflect the reflected light from the document reflected by the first mirror  26  are attached so as to be perpendicular to one another at the second carriage  28 . The second carriage  28  is driven so as to be coupled with the first carriage  27  by the toothed belt that drives the first carriage  27 , or the like, and is moved in parallel along the document platen  8  at a half-speed of that of the first carriage  27 .  
         [0021]     Furthermore, below the document platen  8 , there are disposed an imaging lens  32  for focusing the reflected light from the third mirror  31  on the second carriage  28 , and a CCD (photoelectric conversion element)  34  for receiving and photoelectrically converting the focused reflected light by the imaging lens. The imaging lens  32  is disposed so as to be movable via a driving mechanism within the plane including the optical axis of the light reflected by the third mirror  31 , and forms the reflected light into an image at a desired magnification due to the image-forming lens  32  itself moving. Then, the CCD  34  photoelectrically converts the incident reflected light, and outputs an electric signal corresponding to the read document.  
         [0022]     On the other hand, the printer unit  6  has a laser exposure device  40  serving as latent image forming means. The laser exposure device  40  has a semiconductor laser serving as a light source, a polygon mirror serving as a scanning member which continuously reflects the laser beam radiated from the semiconductor laser, a polygon motor serving as a scanning motor which drives the polygon mirror so as to be rotated at a predetermined rotation speed, and an optical system which reflects the laser beam from the polygon mirror and which guides the reflected laser beam to a photosensitive drum  44  which will be described later.  
         [0023]     Moreover, the printer unit  6  has the freely rotatable photosensitive drum  44  which is disposed at the substantial center of the apparatus body and serves as an image carrier. The peripheral surface of the photosensitive drum  44  is exposed by the laser beam from the laser exposure device  40 , and a desired electrostatic latent image is formed thereon. At the periphery of the photosensitive drum  44 , there are arranged an electrifying charger  45  which electrifies the peripheral surface of the photosensitive drum  44  to a predetermined electric charge, a developing machine unit  46  which supplies a toner serving as a developer to the electrostatic latent image formed on the peripheral surface of the photosensitive drum  44  to carry out development at a desired picture image density, and a transfer charger  48  which transfers a toner image formed on the photosensitive drum  44  onto a paper.  
         [0024]     At the lower portion of the apparatus body, an upper stage cassette  52  and a lower stage cassette  54  which can be respectively withdrawn from the apparatus body are disposed in a state of superimposing on one another. A large capacity feeder  55  is provided at the side of these cassettes, and a paper feeding cassette  57  serving as a hand feed tray  56  as well is mounted so as to be freely attachable and detachable above the large capacity feeder  55 .  
         [0025]     A resist roller pair  65  is provided at the upper stream side of the photosensitive drum  44 . The resist roller pair  65  corrects an inclination of the ejected paper sheet, and matches the front end of the toner image on the photosensitive drum  44  with the front end of the paper sheet, and feeds the paper sheet to a transfer belt unit  49  at a speed which is the same as a moving speed of the peripheral surface of the photosensitive drum  44 .  
         [0000]     &lt;Image Processing Method of Image Forming Apparatus&gt; 
         [0026]     Next, an image processing method of the image forming apparatus will be described in detail with reference to flowcharts.  
         [0000]     (Operations at the Time of Copying)  
         [0027]     First, the operations at the time of copying of the image forming apparatus will be described in detail with reference to the flowchart of  FIG. 3 . At the time of copying, an image is read at scanner unit  111  (S 11 ). Then, with respect to the read image, various corrections, filtering processing, binarizing, etc. are carried out at the image processing circuit  112  (S 12 ). Thereafter, the processed image is transmitted to the image memory controller  105  (S 13 ).  
         [0028]     The image data transmitted from the image processing circuit  112  is temporarily written into a scanner buffer in the image memory  106 . In parallel therewith, image data is successively read out of the scanner buffer, and compressed by the first image compression circuit in the image memory controller  105  (S 14 ). The compressed data is transmitted to the first encoding circuit and encoded (S 15 ), and is returned to the image memory  106  again.  
         [0029]     Next, the encoded compressed image data is read out of the image memory  106  (S 16 ), and is transmitted via the system controller  102  to the IDE-I/F  108  connected to a PCI bus. The hard disk drive  109  (hereinafter HDD) is connected to the IDE-I/F, and the encoded compressed image data is written and stored into the HDD (S 17 ).  
         [0030]     Next, the encoded compressed image data stored in the HDD  109  is read out again (S 17 ), and is stored in the image memory  106  (S 18 ). Then, the compressed image data is transmitted to the image memory controller  105 , and the decoding thereof is performed by the internal first decoding circuit (S 20 ). Thereafter, the image data is uncompressed by being expanded at the first image expansion circuit (S 21 ), and the data returns to the original image data. The image data is written into the page buffer in the image memory  106 .  
         [0031]     The data written in the page buffer is read out with a timing of the printer unit (S 22 ), and is inputted to the image processing circuit  113  via the image memory controller  105 . Here, image processing such as smoothing or the like is carried out thereon (S 23 ), and the data is transmitted to the printer unit and printed (S 24 ). When two or more originals which are the same are outputted, the data stored in the HDD is read out again, and printed.  
         [0032]     Normally, after the entire printing is completed, the data stored in the HDD is erased. However, when a user instructed to maintain the contents of the HDD from the operation panel  110 , the data is not erased, but maintained as is.  
         [0033]     The user can arbitrarily print the stored data by instructing from the operation panel as needed. There is described above the processing method, which uses a scanner or the like in the image forming apparatus, at the time of copying.  
         [0000]     (Operations at the Time of Printer)  
         [0034]     Next, the operations at the time of printing of the image forming apparatus will be described hereinafter with reference to  FIG. 4 .  FIG. 4  is the flowchart showing another example of the image processing of the image forming apparatus. In  FIG. 4 , at the time of a printing operation, data described in a page description language such as Postscript, or PCL is inputted from an external device such as, mainly, a personal computer, which is connected to the external I/F  107  (S 31 ).  
         [0035]     At the time of a printing operation, the printing data inputted from the external I/F  107  is temporarily spooled (S 32 ). Thereafter, the CPU  101  analyzes the page description language of the printing data, and expands it into raster image data (S 33 ). The expanded image data is temporarily stored in the main memory (S 34 ).  
         [0036]     Because the image data prepared by the CPU has a large capacity, the image data is transmitted to the compression accelerator  104 , and compressed by the internal second compression circuit (S 35 ). The compressed image data is encoded by the second encoding circuit in the compression accelerator in the same way (S 36 ). The encoded compressed image data is temporarily stored in the main memory again.  
         [0037]     Next, the encoded compressed image data is read out of the main memory (S 37 ), and is transmitted via the system controller  102  to the IDE-I/F  108  connected to the PCI bus. The hard disk drive  109  (hereinafter HDD) is connected to the IDE-I/F, and the encoded compressed image data is written and stored into the HDD  109  (S 38 ).  
         [0038]     Hereinafter, the encoded compressed image data stored in the HDD  109  is transmitted to the printer unit  114  through the same route at the time of copying.  
         [0039]     Namely, the encoded compressed image data stored in the HDD  109  is read out by the image memory  106  via the IDE-I/F  108 , the system controller  102 , and the image memory controller  105  (S 39 , S 40 ). Then, the encoded compressed image data is transmitted to the image memory controller  105  again, and the decoding thereof is performed by the internal first decoding circuit (S 41 ). Thereafter, the image data is uncompressed at the first image expansion circuit (S 42 ), and the image data returns to the original data prepared by the CPU. The image data is written into the page buffer in the image memory  106 .  
         [0040]     The data written in the page buffer is read out with a timing of the printer unit (S 43 ), and is inputted to the image processing circuit  113  via the image memory controller  105 . Here, image processing such as smoothing or the like is carried out thereon (S 44 ), and finally, the data is transmitted to the printer unit  114  and printed (S 45 ). Here, when two or more originals which are the same are outputted, the data stored in the HDD  109  is read out again, and printed.  
         [0041]     Basically, after the entire printing is completed, the data stored in the HDD  109  is erased. However, when a user instructs to maintain the contents of the HDD  109  in advance at the time of instructing of printing from the external device, the data is not erased, but maintained as is. The user can instruct to merely store the image into the HDD  109  without printing. In addition, in the same way as in the case of copying, the user can arbitrarily print the data stored in the HDD  109 .  
         [0000]     (Operations when Copying and Printing are Simultaneously Requested)  
         [0042]     Next, a case where copying and a printing operations are simultaneously requested will be described. In the image forming apparatus, because there are respectively provided the image memory controller  105  serving as the encoding-decoding and compression-expansion functions of the copying system and the system controller  102  serving as the encoding-decoding and compression-expansion functions of the printer system which are independent of each other, basically, processings on two image information can be independently processed in parallel.  
         [0043]     However, when a copying operation and a a printing operation are simultaneously requested, as an example, there are cases in which the copying operation is given priority. This is the specification which is under consideration of the convenience of the user. The copying operation is carried out in the same way as described above. Because the printer unit  114  is occupied by the copying operation, the a printing operation is in a standby state with the encoded compressed image data stored in the HDD  109 .  
         [0044]     After the copying operation is completed, the encoded compressed image data stored in the HDD  109  for a a printing operation is transmitted to the printer unit  114  and printed by the same procedure as described already.  
         [0045]     In the a printing operation, it takes a relative long time for the CPU  101  to analyze the page description language of the printing data, and to expand it into raster image data. In the case described above, because the CPU  101  can carry out developing work into raster image data during the copying operation, at the time of printing after the copying is completed, the image data already prepared is outputted, so that it is possible to rapidly output without the printer unit  114  being made to wait. This operation is possible because the image forming apparatus of the present invention has the respective circuits for compression and encoding of two systems independent of one another.  
         [0046]     Further, the compression accelerator  104  processes the data on the main memory  103 . On the other hand, the image memory controller  105  processes the data on the image memory  106  which the image memory controller  105  itself manages. In this way, because the compression accelerator  104  and the image memory controller  105  respectively use the separate memories, memory accessing conflicts do not arise, even in a situation in which the compression accelerator  104  and the image memory controller  105  respectively operate, so that there is no deterioration in the performance thereby.  
         [0047]     Moreover, the compression accelerator  104  has the second decoding circuit and the second expansion circuit built-in. In a case where the compressed image data encoded and stored in the HDD  109  is edited at the CPU  101 , by using these circuits, it is possible to operate at a speed higher than a case where the CPU processes by using only software. Because this operation can be operated independently of the copying operation, even when this operation is requested to be executed with the copying operation at the same time, it is possible to cope therewith without the entire performance deteriorating.  
         [0000]     (Reading from the Exterior)  
         [0048]     There are cases where the second decoding circuit and the second expansion circuit of the compression accelerator  104  are used for reading out the compressed image data encoded and stored in the HDD  109  on an external device such as, mainly, a personal computer, which is connected to the external I/F  107 .  
         [0000]     (Simplification of Compression Processing and Encoding Processing, and Expansion Processing and Decoding Processing)  
         [0049]     Moreover, the compression processing and encoding processing, and the expansion processing and decoding processing which have been described above can be respectively simplified by replacing those with one-time information conversion processing. Namely, because all of the compression processing and encoding processing, and the expansion processing and decoding processing are the processings for converting information, the conversion processing of the compression unit and the conversion processing of the encoding unit are synthesized, and the image information can be converted into the encoded compressed image information by the synthesized one-time conversion processing. By carrying out such processing, it is possible to make a conversion time and memory resources.  
         [0050]     In the same way, decoding conversion processing and expansion conversion processing of the decoding expansion unit are synthesized, and the compressed image information encoded by the encoding unit can be converted into the image information by the synthesized one-time conversion processing. Similarly, by carrying out such processing, it is possible to make a conversion time and memory resources in small scales.  
         [0051]     As shown in step S 25  in the flowchart of  FIG. 5 , such a simplification of the compression processing and encoding processing, and the expansion processing and decoding processing is possible in the encoding processing and the compression processing of the image memory controller  105 . Further, as shown in step S 26  in the flowchart of  FIG. 5 , it is possible in the decoding processing and the expansion processing of the image memory controller  105 .  
         [0052]     In the same way, as shown in step S 46  in the flowchart of  FIG. 6 , such a simplification of the compression processing and encoding processing, and the expansion processing and decoding processing is possible in the encoding processing and the compression processing of the compression accelerator  104 . Further, as shown in step S 47  in the flowchart of  FIG. 6 , it is possible in the decoding processing and the expansion processing of the compression accelerator  104 .  
         [0000]     (Non-compression/Non-encoding Mode)  
         [0053]     Moreover, in the CPU  101 , which is, for example, the control unit, of the image forming apparatus, it is preferable that there is provided a non-compression/non-encoding mode in which neither the compression processing nor encoding processing onto the image information is carried out in the compression unit and the encoding unit. By selecting the non-compression/non-encoding mode from the operation panel  110  or the like, the respective units are controlled by the CPU  101  or the like so as to carry out image formation by supplying at least one of the image information on the original and the printing information in the page description language as is to the forming unit. In accordance therewith, by avoiding compression processing and encoding processing of unnecessary image information, rapid image processing can be carried out in accordance with a situation.  
         [0054]     As described above, in the image information apparatus relating to the present invention, the independent chips of the compression processing and encoding processing, and the expansion processing and decoding processing which are independent of one another are provided in the copying system and the printer system, whereby an image of the copying system and an image of the printer system are processed at the separated encoding circuits even when a copying operation and a a printing operation are simultaneously requested. Accordingly, data can be encoded and stored in a hard disk without an increase in a processing time being brought about.  
         [0055]     Moreover, because the data has been prepared on the hard disk, printing of another job made to wait can be started immediately after printing of a prior job is completed, and the operations can be efficiently carried out without the printer being not in use, so that the productivity is improved.  
         [0056]     Further, because the data on the hard disk has been encoded, even if the hard disk is stolen or the hard disk is disposed as remaining the data by some rare accident, there is little possibility of leaking of confidential information. Accordingly, in accordance with the image forming apparatus of the present invention, a multifunction device having a high productivity can be realized while ensuring the safety of data.  
         [0057]     In accordance with various embodiments described above, the skilled in the art can realize the present invention. However, it is easy for those skilled in the art to further conceive of various modified examples of these embodiments, and the present invention can be applied to various embodiments without inventive ability. Accordingly, the present invention extends over a broad range which does not contradict the disclosed principles and the novel features, and is not limited to the embodiments described above.