Abstract:
An image formation apparatus, an image formation method, an image formation program, and a computer-readable recording medium are disclosed. The image formation apparatus, wherein a developer supply roller supplies a developer to a development unit, includes a quality information acquiring unit for acquiring quality information chosen by a user out of a plurality of predefined quality information sets about quality of image formation, an environmental information acquiring unit for acquiring environmental information about a present operational environment of the image formation out of a plurality of predefined environmental information sets, and a controlling unit for controlling rotation of the developer supply roller in order to prevent plugging of the developer supply roller based on the quality information and the environmental information.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an image formation apparatus, an image formation method, an image formation program, and a computer-readable recording medium.  
         [0003]     2. Description of the Related Art  
         [0004]     A conventional method of preventing plugging by toner, a component of developer that is supplied from a toner holder to a development unit of an image formation apparatus, of a toner supply roller is proposed. For example, the method gives vibration to the toner supply roller at predetermined intervals by a vibrating unit that is arranged adjacent to a shaft that supports the toner supply roller or an outside surface of the toner supply roller (for example, Patent Reference 1).  
         [0005]     [Patent reference 1] JPA 11-84872  
         [0006]     [Objective of the Invention] 
         [0007]     However, according to the conventional method, there is a problem in that the vibrator unit is required to include an expensive component such as a piezo-electric vibrator (such as crystal), a porcelain vibrator (such as one using barium titanate), or a magnetostrictive vibrator (such as a ferrite). Further, in order to protect the expensive vibrator, the configuration tends to be complicated, adding further costs.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides an image formation apparatus, an image formation method, an image formation program, and a computer-readable recording medium that substantially obviate one or more of the problems caused by the limitations and disadvantages of the related art.  
         [0009]     More specifically, the present invention offers an image formation apparatus, an image formation method, an image formation program, and a computer-readable recording medium, whereby toner plugging, an apparatus breakdown, and apparatus damage are prevented without a special mechanical configuration.  
         [0010]     Features of embodiments of the present invention are set forth in the description that follows, and in part will become apparent from the description and the accompanying drawings, or may be learned by practice of the invention according to the teachings provided in the description. Problem solutions provided by an embodiment of the present invention may be realized and attained by an image formation apparatus, an image formation method, an image formation program, and a computer-readable recording medium particularly pointed out in the specification in such full, clear, concise, and exact terms as to enable a person having ordinary skill in the art to practice the invention.  
         [0011]     To achieve these solutions and in accordance with an aspect of the invention, as embodied and broadly described herein, an embodiment of the invention provides an image formation apparatus, an image formation method, an image formation program, and a computer-readable recording medium as follows.  
         [0012]     [Means For Solving a Subject] 
         [0013]     In order to solve the problem described above, the embodiment of the present invention provides an image formation apparatus, wherein a developer (toner) supply roller supplies a developer (toner) to a development unit, the image formation apparatus including,  
         [0014]     a quality information acquiring unit for acquiring a quality information set chosen by a user out of two or more predefined quality information sets about the quality of image formation,  
         [0015]     an environmental information acquiring unit for acquiring an environmental information set about the present operational environment out of two or more predetermined environmental information sets about the operational environment of image formation, and  
         [0016]     a controlling unit for controlling rotation of the developer (toner) supply roller in order to prevent plugging of the developer supply roller when forming an image based on the acquired quality information and the acquired environmental information.  
         [0017]     According to another aspect of the embodiment of the present invention, the image formation apparatus includes  
         [0018]     a storage unit for storing a table wherein information about contents of the control to be performed by the controlling unit is associated with the quality information and the environmental information, wherein  
         [0019]     the controlling unit controls the rotational speed, the direction of the rotation, and the rotation time of the developer supply roller based on the table stored in the storage unit.  
         [0020]     According to another aspect of the embodiment of the present invention, the image formation apparatus controls the developer supply roller with a combination of control before the image formation, control performed during the image formation, and control after the image formation based on the table stored in the storage unit.  
         [0021]     According to another aspect of the embodiment of the present invention, the controlling unit measures an interval during which the image formation apparatus has been in a non-operating state (for example, with the power source turned off, or in an energy-saving mode), and rotates the developer supply roller at a predetermined speed for a predetermined time before the image formation, if the measured interval is greater than a predetermined interval.  
         [0022]     The embodiment of the present invention further provides an image formation method, wherein a developer supply roller supplies a developer to a development unit, the image formation method including,  
         [0023]     a quality information acquisition step of acquiring a quality information set chosen by a user out of two or more predefined quality information sets about the quality of image formation,  
         [0024]     an environmental information acquisition step of acquiring an environmental information set about the present operational environment out of two or more predetermined environmental information sets about the operational environment of image formation, and  
         [0025]     a control step of controlling rotation of the developer supply roller in order to prevent plugging of the developer supply roller when forming an image based on the acquired quality information and the acquired environmental information.  
         [0026]     According to another aspect of the embodiment of the present invention, the control step of the image formation method controls the rotational speed, the rotational direction, and the rotation time of the developer supply roller based on stored information, which stored information includes contents of control to be carried out at the control step which contents are associated with the acquired quality information and the environmental information.  
         [0027]     According to another aspect of the embodiment of the present invention, the control step of the image formation method controls the developer supply roller by combining control performed before the image formation, control performed during the image formation, and control after the image formation based on the stored information.  
         [0028]     According to another aspect of the embodiment of the present invention, the control step measures an interval during which the image formation apparatus is in the non-operating state, and rotates the developer supply roller for a predetermined time at a predetermined speed before the image formation, if the measured interval is greater than a predetermined interval.  
         [0029]     The embodiment of the present invention further provides an image formation program for a computer to perform the image formation method of the present invention.  
         [0030]     The embodiment of the present invention further provides a computer-readable recording medium that stores the image formation program of the present invention.  
         [0031]     [Effectiveness of Invention] 
         [0032]     With the image formation apparatus, the image formation method, the image formation program, and the computer-readable recording medium according to the embodiment of the present invention, plugging of a toner supply roller can be prevented with a simple configuration wherein the rotation of the toner supply roller is controlled so that an apparatus breakdown and damage can be prevented. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]      FIG. 1  is a cutaway view of an image formation apparatus according to an embodiment of the present invention;  
         [0034]      FIG. 2  is a hardware block diagram of the image formation apparatus according to the embodiment of the present invention;  
         [0035]      FIG. 3  gives a table of contents of a toner plugging preventive operation carried out by the image formation apparatus according to the embodiment of the present invention; and  
         [0036]      FIG. 4  is a flowchart of the toner plugging preventive operation carried out by the image formation apparatus according to the embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]     In the following, embodiments of the image formation apparatus, the image formation method, an image formation program, and the computer-readable recording medium of the present invention are described with reference to the accompanying drawings.  
       Embodiment  
       [0038]     First, an image formation apparatus  100  according to the embodiment of the present invention is described with reference to  FIG. 1 , which is a cutaway view of the image formation apparatus  100  configured according to the embodiment of the present invention. The image formation apparatus  100  includes:  
         [0039]     toner (developer) supply rollers  101 B,  101 M,  101 C, and  101 Y, collectively referenced as  101 ;  
         [0040]     toner (developer) holders  102 B,  102 M,  102 C, and  102 Y, collectively referenced as  102 ;  
         [0041]     development units  103 B,  103 M,  103 C, and  103 Y, collectively referenced as  103 ;  
         [0042]     photo conductors  104 B,  104 M,  104 C, and  104 Y, collectively referenced as  104 ;  
         [0043]     electrification units  105 B,  105 M,  105 C, and  105 Y, collectively referenced as  105 ;  
         [0044]     an exposure unit  106 ;  
         [0045]     a transfer belt  108 ;  
         [0046]     primary transfer rollers  109 B,  109 M,  109 C, and  109 Y, collectively referenced as  109 ;  
         [0047]     cleaner blades  110 B,  110 M,  110 C, and  110 Y, collectively referenced as  110 ;  
         [0048]     a feed roller  111 ;  
         [0049]     a paper feed tray  112 ;  
         [0050]     a recording medium (paper)  113 ;  
         [0051]     a secondary transfer roller  114 ;  
         [0052]     a fixing assembly  115 ; and  
         [0053]     a delivery roller  116 .  
         [0054]     The image formation apparatus  100  is of a tandem type wherein the toner holders  102 B,  102 M,  102 C, and  102 Y containing toner of colors black (B), magenta (M), cyan (C), and yellow (Y), respectively, are arranged along the transfer belt  108 .  
         [0055]     With reference to  FIG. 1 , the transfer belt  108  rotates counterclockwise, and the toner holders  102 B,  102 M,  102 C, and  102 Y are arranged in this sequence from the upstream side of rotation of the transfer belt  108 . The toner holders  102 B,  102 M,  102 C, and  102 Y are identical to each other, except that each toner holder contains toner of a uniquely assigned color as described above. Then, in the following, the toner holder  102 B and the toner supply roller  101 B are described as the representatives of the toner holders  102  and the toner supply rollers  101 , respectively.  
         [0056]     When forming an image, the toner supply roller  101 B shown in  FIG. 1  is rotated clockwise (the clockwise rotational direction is called a “positive direction”, a rotation in the positive direction is called a “positive rotation”, a counterclockwise rotational direction is called a “negative direction”, and a rotation in the negative direction is called a “negative rotation”), and supplies black toner contained in the toner holder  102 B to the corresponding development unit  103 B. The rotational speed of the toner supply roller  101 B can be adjusted between 50 mm/sec and 160 mm/sec, where the rotational speed of 160 mm/sec is called a “full speed”.  
         [0057]     The surface of the photo conductor  104 B is uniformly charged by the electrification unit  105 B. Then, the exposure unit  106  irradiates and exposes a laser light  107 B corresponding to the image of black onto the photo conductor  104 B that is uniformly charged by the electrification unit  105 B. In this way, an electrostatic latent image of the black image is formed on the photo conductor  104 B.  
         [0058]     The development unit  103 B forms a toner image by applying the black toner to the electrostatic latent image, and the black toner image is formed on the photo conductor  104 B. The black toner image is transferred onto the transfer belt  108  by the primary transfer roller  109 B at a primary transfer position where the photo conductor  104 B and the transfer belt  108  make contact. In this way, the toner image formed with the black toner is placed on the transfer belt  108 . Then, the cleaner blade  110 B wipes away residual toner that remains on the surface of the photo conductor  104 B so that it is ready for the next image formation. Similarly, toner images in magenta, cyan, and yellow are formed on the transfer belt  108  so that all the toner images may be superposed.  
         [0059]     The secondary transfer roller  114  transfers the superposed toner image to the paper  113  conveyed from the paper feed tray  112  with the feed roller  111 . Then, the fixing assembly  115  fixes the toner image to the paper  113 . Then, the paper  113  on which the toner image is fixed is discharged to the exterior of the image formation apparatus  100  by the delivery roller  116 .  
         [0060]     Now, in image formation, low-speed printing is performed when, e.g., printing onto pasteboard, and printing at high density. If low-speed printing is continuously performed for a long time, since the flow of the toner in the vicinity of the toner supply rollers  101  becomes slow, there is a problem in that toner plugging of the toner supply rollers  101  is generated. If the operation is forced to continue with toner plugging occurring, the amount of the toner being supplied to the photoconductors  104  falls, and printing consistency becomes low. In the worst case, the toner supply rollers  101  may be damaged, and use of the image formation apparatus  100  may become impossible. Then, the image formation apparatus  100  according to the embodiment of the present invention prevents toner plugging by controlling the rotational speed, the rotational direction, and the rotation time of the toner supply rollers  101  before, during, and after image formation.  
         [0061]     Next, the hardware configuration of the image formation apparatus  100  according to the embodiment of the present invention is described with reference to a block diagram in  FIG. 2 . As shown in  FIG. 2 , the image formation apparatus  100  includes a CPU  201 , a storage unit  202 , an LSI  203  for I/O control, a motor  204 , a clutch  205 , a drive transfer device  206 , and the toner supply rollers  101 B,  101 M,  101 C, and  101 Y, and a computer-readable recording medium  207  such as a CD-ROM for storing the image formation program.  
         [0062]     The CPU  201  is for controlling processes of the image formation apparatus  100 . Further, the CPU  201  performs a toner plugging preventive operation before image formation, during image formation, and after image formation. The storage unit  202  stores information about the rotational speed, the rotational direction, and the rotation time of the toner supply rollers  101  for the toner plugging preventive operation.  
         [0063]     Further, the CPU  201  controls the motor  204  and the clutch  205  by the LSI  203  for I/O control. The motor  204  is for rotating the toner supply rollers  101  through the drive transfer device  206 . Further, the clutch  205  is for stopping the rotation of the toner supply rollers  101  through the drive transfer device  206 . The rotational speed, the rotational direction, and the rotation time of the toner supply rollers  101  can be adjusted by the CPU  201  controlling the motor  204  through the LSI  203  for I/O control.  
         [0064]     Next, the toner plugging preventive operation performed by the image formation apparatus  100  according to the embodiment of the present invention is described with reference to a table given in  FIG. 3 . First, a critical rotational speed S at which toner plugging may occur is described. The critical rotational speed S varies with the operational environment (such as temperature and humidity), quality and magnitude of the toner, the toner supply roller  101 , and the toner holder  102 . Here, about the configuration shown in  FIG. 1 , parameters Z are defined, namely, the diameter of toner (grain) is about 8 μm, the diameter of the toner supply rollers  101  is about 10 mm, and the smallest distance between the wall of each toner holder  102  and the corresponding toner supply roller  101  is about 0.75 mm. With the parameters Z, experiments conducted by the inventor hereto show that toner plugging can occur at a rotational speed of 60 mm/s or less. Accordingly, the critical rotational speed S is defined as 60 mm/s.  
         [0065]     Further, the experiments show that the probability of toner plugging occurring depends on the time or the number of sheets processed when the toner supply rollers  101  are rotating below the critical rotational speed S. Specifically, if the operational environment is poor with the parameters Z, whenever one sheet is printed, toner plugging may occur; if the operational environment is normal, toner plugging may occur in 300 seconds or more; and if the operational environment is good, toner plugging does not occur.  
         [0066]     Further, the experiments show how long the non-operating state of the toner supply rollers  101  may last before the toner plugging preventive operation should start. Specifically, with the parameters Z, toner plugging may occur if the non-operating state lasts 24 hours or more (non-operating state is such as a power source being turned off, or being in an energy-saving mode). Further, in the case that the non-operating state continues 24 hours or more, the experiments show that toner plugging can be fully prevented if the toner supply rollers  101  are rotated at the full speed in the positive direction for 2 seconds.  
         [0067]     Next, the rotational speed of the toner supply rollers  101 , at which rotational speed toner plugging can be prevented, is described. The experiments show that toner plugging can be prevented if the rotational speed of the toner supply rollers  101  is 150 mm/s or greater with the parameters Z.  
         [0068]     Further, the experiments show that, with the parameters Z, toner plugging of the toner supply rollers  101  can be prevented if the toner supply rollers  101  are rotated at the full speed (160 mm/s) for 2 to 10 seconds in either of the positive and the negative directions. Specifically, when the operational speed of the toner supply rollers  101  is less than the critical rotational speed S (60 mm/s), at which speed toner plugging may be generated, toner plugging can be prevented by rotating the toner supply rollers  101  at the full speed for 10 seconds if during the operation,  
         [0069]     at the full speed for 2 seconds if resuming operations from the non-operating state, and  
         [0070]     at the full speed for 4 seconds in the positive direction and at the full speed for 2 seconds in the negative direction if entering the non-operating state.  
         [0071]     Information about the contents (specific operations) of the toner plugging preventive operation that the image formation apparatus  100  performs is defined based on the experimental results, which information is stored in the storage unit  202 .  FIG. 3  is a table showing the contents of the toner plugging preventive operation that the image formation apparatus  100  according to the embodiment of the present invention performs. With reference to  FIG. 3 , the image formation apparatus  100  performs the toner plugging preventive operation based on the kind of printing request that is input by a user. Here, for example, three kinds are offered, namely, speed important, normal, and quality important. Further, the toner plugging preventive operation is based on the environmental conditions, which conditions are, for example, poor, normal, and good. Here, the CPU  201  determines the environmental condition based or operational environmental factors such as temperature and humidity.  
         [0072]     For example, if the printing request that the user has input is “speed important”, and if the environmental condition is “poor”, the toner supply rollers  101  are rotated at the full speed in the positive direction for 10 seconds every 600 seconds during printing as shown in  FIG. 3 . Then, after printing, the toner supply rollers  101  are rotated at the full speed for 4 seconds in the positive direction, and at the full speed in the negative direction 2 seconds. If the printing request that the user has input is “normal”, and if the environmental condition is “normal”, the toner supply rollers  101  are rotated at the full speed in the positive direction for 10 seconds every 300 seconds during printing as shown in  FIG. 3 . Then, after printing, the toner supply rollers  101  are rotated at the full speed in the positive direction for  4  seconds, and then are rotated at the full speed in the negative direction for 2 seconds. Further, if the printing request that the user has input is “quality important”, and if the environmental condition is “good”, the toner supply rollers  101  are rotated at the full speed in the positive direction for 2 seconds before printing as shown in  FIG. 3 .  
         [0073]     Next, with reference to  FIG. 4 , process steps of the toner plugging preventive operation carried out by the image formation apparatus  100  according to the embodiment of the present invention are described.  FIG. 4  is a flowchart that shows the process steps of the toner plugging preventive operation. As shown in  FIG. 4 , first, whether the CPU  201  receives a printing request is determined at step S 401 . The printing request is issued by the user operating a control panel (not illustrated). Here, three choices are available as for the printing request in this example as described above, namely, speed important, normal, and quality important.  
         [0074]     At step S 401 , if no printing request is received (No at step S 401 ), the process returns to step S 401 ; and if the printing request is received (Yes at step S 401 ), the process proceeds to step S 402  wherein the CPU  201  determines the environmental condition. Three environmental conditions are available for selection in this example as described above, namely, poor, normal, and good. The CPU  201  determines a choice based on operational environment factors such as temperature and humidity.  
         [0075]     Then, at step S 403 , the CPU  201  determines whether the non-operating state has lasted for 24 hours or more. If the determination is negative (No at step S 403 ), the process proceeds to step S 405  wherein the toner plugging preventive operation before printing is performed.  
         [0076]     Otherwise, if the determination at step S 403  is affirmative (Yes at step S 403 ), the CPU  201  causes the toner supply rollers  101  to rotate at the full speed in the positive direction for 2 seconds at step S 404 . Specifically, the CPU  201  rotates the motor  204  through the LSI  203  for I/O control, and rotates the toner supply rollers  101  at the full speed in the positive direction for 2 seconds through the drive transfer device  206 .  
         [0077]     Then, at step S 405 , the CPU  201  performs the toner plugging preventive operation before printing. Specifically, if, for example, the printing request acquired at step S 401  is “quality important”, and if the environmental condition determined at step S 402  is “normal”, the information for the toner plugging preventive operation before printing corresponding to “quality important” and “normal” environment is read from the storage unit  202  (refer to  FIG. 3 ), and the toner supply rollers  101  are rotated at the full speed in the positive direction for 2 seconds.  
         [0078]     Then, at step S 406 , the CPU  201  starts printing. While printing, the CPU  201  performs the toner plugging preventive operation during printing at step S 407 . For example, if the printing request acquired in step S 401  is “quality important”, and the environmental condition determined at step S 402  is “normal”, the CPU  201  reads the information about the toner plugging preventive operation during printing corresponding to “quality important” and “normal” environment from the storage unit  202  (refer to  FIG. 3 ), and rotates the toner supply rollers  101  at the full speed in the positive direction for 10 seconds every 300 seconds during printing.  
         [0079]     Then, the CPU  201  ends printing at step S 408 . After printing, the CPU  201  performs the toner plugging preventive operation after printing at step S 409 , and the series of processes is ended. Specifically, for example, if the printing request acquired in step S 401  is “quality important” and the environmental condition determined in step S 402  is “normal”, the toner plugging preventive operation after printing is rotating the toner supply rollers  101  at the full speed in the positive direction for 4 seconds and rotating the toner supply rollers  101  at the full speed in the negative direction for  2  second as shown in  FIG. 3 .  
         [0080]     As described above, according to the embodiments of the present invention, the image formation apparatus, the image formation method, the image formation program, and the computer-readable recording medium can be provided. According to them, plugging by toner can be prevented by only controlling the rotation of the toner supply roller so that the apparatus breakdown and damage can be prevented.  
         [0081]     The embodiment of the image formation method as described above can be realized by a computer, such as a personal computer or a workstation, executing a program comprising the above process steps beforehand prepared. The program may be stored in a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, a MO, and a DVD, and is executed by the computer reading from the recording medium. Further, the program may be obtained through a transmission medium that can distribute the program through networks such as the Internet.  
         [0082]     [Availability to Industry] 
         [0083]     As described above, the image formation apparatus, the image formation method, the image formation program, and the computer-readable recording medium of the present invention are useful to in multifunction machines having, e.g., copying, facsimile, and printer functions; and are especially suitable for a copying machine that reads a manuscript and prints an output.  
         [0084]     Further, the present invention is not limited to these embodiments, but variations and modifications may be made without departing from the scope of the present invention.  
         [0085]     The present application is based on Japanese Priority Application No. 2006-032388 filed on Feb. 9, 2006 with the Japanese Patent Office, the entire contents of that are hereby incorporated by reference.