Patent Publication Number: US-2019187611-A1

Title: Image forming apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. § 119 to Japanese patent Application No. 2017-241349, filed on Dec. 18, 2017, is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Technological Field 
     The present invention relates to an image forming apparatus. 
     Description of the Related art 
     There are conventional image forming apparatuses such as an electrophotographic complex machine that forms an image on a paper sheet using toner. In an image forming apparatus, scattering or leakage of toner occurs during a process such as development, and ozone is generated by the discharge during the process of charging the photoreceptors (drums). The generation of toner and ozone results in a mixed odor of an ultra fine particles (UFP) odor caused by the toner as UFP and an ozone odor caused by the ozone. 
     To counter this, there is a known image forming apparatus that eliminates and deodorizes odor components generated from the resin, the toner, and the carrier, having a structure in which microorganisms are contained in a porous stirring member or a hollow stirring member with porous surfaces (see JP 2009-286448 A). 
     The image forming apparatus of JP 2009-286448 A is designed to eliminate generated odor components, but is not designed to prevent generation of odor components. 
     The following aspects of an image forming apparatus are also known: (1) in a high-humidity environment (in moisture), (2) ozone generated in a charger and (3) scattered toner from a developing machine chemically react with each other because of the high voltage at the charger, and as a result, (4) unusual odor (butanol) is generated. The contribution of the (3) scattered toner to the generation of the (4) butanol is greater than that of the (1) high-humidity environment and the (2) ozone. 
     Even if an ozone filter is used to eliminate the (4) butanol, the ozone filter eliminates the unusual odor components with its adsorptive properties. Therefore, once the unusual odor components adsorb onto the filter surface, the removal performance becomes ineffective, and the ozone filter becomes poorer in filter durability. As a result, the frequency of ozone filter exchange and the frequency of dispatch of a service person increase, the labor costs become higher, and the component costs also become higher due to the larger surface area. For example, in a case where the ozone filter has a shape that is 80 mm in length, 40 mm in width, and 15 mm in thickness, and the ozone decomposing performance maintains a level of 90% when printing has been performed on about 600,000 paper sheets, the ozone filter against unusual odor drops to such a level that the ozone filter needs to be replaced when printing has been performed on about 100,000 paper sheets. 
     SUMMARY 
     An object of the present invention is to prevent generation of unusual odor, and lower the labor costs and the component costs required in removing unusual odor. 
     To achieve the abovementioned object, according to an aspect of the present invention, an image forming apparatus reflecting one aspect of the present invention comprises: a charger that charges a photoreceptor; a developing part that develops a toner image on the charged and exposed photoreceptor; a detector that detects at least one of humidity, ozone generated from the charger, and toner scattered from the developing part; and a processor that performs a process of reducing at least one of the detected humidity, ozone, and scattered toner, when the at least one of the detected humidity, ozone, and scattered toner is equal to or higher than a predetermined threshold value, predetermined threshold values having been set beforehand for humidity, ozone, and scattered toner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention: 
         FIG. 1  is a schematic view of the structure of an entire image forming apparatus according to an embodiment of the present invention; 
         FIG. 2  is a functional block diagram showing the control configuration of the image forming apparatus; 
         FIG. 3  is a schematic view of a collection mechanism; 
         FIG. 4  is a flowchart showing a first unusual odor prevention process; 
         FIG. 5A  is a diagram showing a prediction judgment table; 
         FIG. 5B  is a diagram showing a process table; and 
         FIG. 6  is a flowchart showing a second unusual odor prevention process. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, one or more embodiments and modification of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments and examples shown in the drawings. 
     1. Embodiment 
     Referring to  FIG. 1  to  FIG. 4 , an embodiment according to the present invention is described. 
     1-1. Structure of an Entire Image Forming Apparatus 
     Referring first to  FIG. 1  and  FIG. 2 , the structure of an entire image forming apparatus  1  according to this embodiment is described.  FIG. 1  is a schematic view of the structure of the entire image forming apparatus  1 .  FIG. 2  is a functional block diagram showing the control configuration of the image forming apparatus  1 . 
     As shown in  FIG. 1 , the image forming apparatus  1  is a tandem-type color-image forming apparatus that forms images on paper sheets by an electrophotographic method, and overlap toners of four colors, which are yellow (Y), magenta (M), cyan (C), and black (K), on one another. 
     As shown in  FIG. 2 , the image forming apparatus  1  includes a sheet storage unit  10 , an image reading unit  20 , an image forming part  30 , a fixing unit  40 , a control unit  50 , a storage unit  60 , an operation display part  70 , a detector  80 , a communicator  90 , a collection mechanism  100 , and an internal heater HE 1 , for example. The respective components of the image forming apparatus  1  are connected via a bus. As shown in  FIG. 1 , the image forming apparatus  1  also includes an indoor hygrometer HY 1  that is communicatively connected via the communicator  90 . 
     The sheet storage unit  10  is disposed at a lower portion of the image forming apparatus  1 , and trays  11  corresponding to the sizes and types of paper sheets are provided therein. In the sheet storage unit  10  under the control of the control unit  50 , a paper sheet is supplied from a tray  11 , and is conveyed to a conveying unit  12 . The conveying unit  12  then conveys the paper sheet to the image forming part  30  and the fixing unit  40 . 
     Under the control of the control unit  50 , the image reading unit  20  reads an image of a document conveyed by a document conveying unit (not shown) or a document placed on a document table  21 , and then generates image data. The image reading unit  20  also performs processing such as shading correction, dithering, or compression on image data generated through A-D conversion, and stores the processed image data into a RAM of the control unit  50  described later. The image data is not necessarily data that is output from the image reading unit  20 , but may be data that is received from an external device such as a personal computer or another image forming apparatus connected to the communicator  90  described later. 
     The image forming part  30  forms an image on a paper sheet, in accordance with an image forming job (hereinafter simply referred to as a “job”). The image forming part  30  includes four image forming units  30 Y,  30 M,  30 C, and  30 K corresponding to the respective color components Y, M, C, and K, an intermediate transfer belt  33 , and a transfer roller  34 . 
     Each of the image forming units  30 Y,  30 M,  30 C, and  30 K includes a drum-like photoreceptor  31 , a developing part  32  and a charger  35  disposed around the photoreceptor  31 , an exposure unit and a cleaning unit (not shown), and the like. 
     Under the control of the control unit  50 , the charger  35  charges the photoreceptor  31  with charge pressure. When the charge voltage becomes higher, the charger  35  changes the oxygen in the apparatus into ozone by discharging. Because of this, ozone can be generated. The exposure unit emits laser light onto the charged photoreceptor  31 , and thus, exposes the photoreceptor  31 . As a result, an electrostatic latent image is formed on the photoreceptor  31 . Under the control of the control unit  50 , the developing part  32  supplies toner of a predetermined color (Y, M, C, or K) onto the exposed photoreceptor  31  with a charged developing roller  32   a , and develops the electrostatic latent image formed on the photoreceptor  31 . 
     The developing part  32  stores the toner for development and the carrier for transferring the toner onto the photoreceptor  31 . However, the developing part  32  does not necessarily have this structure, and may be designed to store only the toner. The developing part  32  also includes a duct  32   b  as a path for attracting the toner scattered during the development. 
     Images (single-color images) formed with toner of Y, M, C, and K on the four photoreceptors  31  corresponding to Y, M, C, and K, respectively, are transferred onto the intermediate transfer belt  33  one by one from the respective photoreceptors  31  in a superimposing manner. As a result of this, a toner image having Y, M, C, and K as the color components is formed on the intermediate transfer belt  33 . The intermediate transfer belt  33  is an endless belt wound around conveying rollers, and rotates with the respective conveying rollers. A bias of the opposite polarity from that of the toner is then applied to the transfer roller  34 , so that the toner image formed on the intermediate transfer belt  33  is transferred onto a paper sheet. 
     In this embodiment, the image forming apparatus  1  includes the collection mechanism  100  for collecting toner scattered in the above described four image forming units  30 Y,  30 M,  30 C, and  30 K, and ozone generated from the charger  35 . The collection mechanism  100  will be described later in detail. 
     Under the control of the control unit  50 , the fixing unit  40  heats and pressurizes the paper sheet on which the toner image is formed by the image forming part  30 . The fixing unit  40  includes an endless fixing belt  41  as a heating member, a heating roller  42 , a fixing roller  43  disposed to face a pressure roller  44 , the pressure roller  44 , and an air separating unit  45 . The fixing belt  41  is stretched by the heating roller  42  and the fixing roller  43 . The heating roller  42  includes a heating means such as a halogen heater (not shown) that heats the fixing belt  41 . The fixing roller  43  forms a nip portion N between the fixing belt  41  and the pressure roller  44 . 
     In the above structure, when the pressure roller  44  is rotated in the counterclockwise direction by a drive means (not shown), the fixing belt  41 , the heating roller  42 , and the fixing roller  43  rotatively move or rotate in the clockwise direction. The fixing belt  41  is heated by the heating roller  42  in contact therewith, and the fixing roller  43  is also heated. The paper sheet on which the toner image is formed passes through the nip portion N, so that the paper sheet is heated and pressurized, and the toner image transferred onto the paper sheet is melted and fixed. 
     Under the control of the control unit  50 , the air separating unit  45  blows air against the paper sheet being discharged from the nip portion N, to separate the paper sheet from the fixing belt  41 . The air separating unit  45  includes a suction fan (not shown) that sucks air from the outside and sends the air toward the nip portion N, and a duct that is a path of the sent air. As the paper sheet is separated from the fixing belt  41  by the air separating unit  45 , it is possible to separate the paper sheet without bringing a member such as a separating claw into contact with the surface of the fixing belt  41 . Thus, the surface of the fixing belt  41  is damaged. 
     Meanwhile, the pressure roller  44  has a driving structure that can separate the pressure roller  44  from the fixing roller  43  under the control of the control unit  50 . The fixing roller  43  and the pressure roller  44  are separated from each other, and the air blown by the air separating unit  45  passes through the separation portion, so that warm air can be sent toward the chargers  35  of the image forming part  30 . 
     The control unit  50  includes a central processing unit (CPU) and a random access memory (RAM), for example. The CPU of the control unit  50  reads various kinds of programs, such as a system program and a processing program, from the storage unit  60 , and loads the programs into the RAM. In accordance with the loaded programs, the CPU performs various kinds of processes, such as an image forming process and a toner collecting process. 
     The storage unit  60  is formed with a hard disk drive (HDD) or a nonvolatile semiconductor memory, for example. The storage unit  60  stores various kinds of programs such as the system program and the processing program to be executed by the control unit  50 , and the data necessary for executing these programs. Particularly, the storage unit  60  stores a first unusual odor prevention program for performing a first unusual odor prevention process that will be described later. 
     The operation display part  70  includes a display part that displays various kinds of information on a display screen, and an operating unit that accepts inputs of various kinds of instructions from the user. Under the control of the control unit  50 , the operation display part  70  displays display information on the display part, and outputs information that has been input to the operation unit, to the control unit  50 . 
     The detector  80  detects various kinds of information, and outputs the detected information to the control unit  50 . The detector  80  includes an internal humidity sensor  81 , an ozone sensor  82 , a particle counter  83 , and an unusual odor detecting sensor  84 . The internal humidity sensor  81  is disposed in the image forming apparatus  1 . For example, the internal humidity sensor  81  is a detector that is disposed in the vicinity of the image forming part  30  (the chargers  35 ), and detects humidity. The ozone sensor  82  is a detector that is disposed in a suction duct  111  for each color in a duct unit  110  of the collection mechanism  100 , for example, and detects the ozone concentration in the sucked air. 
     The particle counter  83  is a measuring instrument that is disposed in a suction duct  112  for each color in the duct unit  110  of the collection mechanism  100 , for example, and counts toner particles as the fine particles in the sucked air. The particle counter  83  is of a light scattering type, and carries out measurement by measuring the intensity of light scattering from toner particles and extracting an electrical signal indicating the light intensity proportional to the size of the toner particles. The particle counter  83  may be of a light shielding type. The unusual odor detecting sensor  84  is a detector that is disposed in a flow path on the downstream side of a filter unit  126  of a collector  120  of the collection mechanism  100 , for example, and detects the gas concentration of butanol as an unusual odor component. 
     The detector  80  also includes a voltage measuring unit that measures the charge pressure of the charger  35  of each color of the image forming units  30 Y,  30 M,  30 C, and  30 K. The high-voltage discharge condition of the charger  35  is determined by the voltage, the current, and the time. When the charge pressure as the voltage rises, the discharge amount of the charger  35  also increases, and the discharge further leads to an increase in the amount of generated ozone. 
     The communicator  90  is formed with a network card or the like, and is connected to a communication network including the Internet, a dedicated line, and the like. The communicator  90  exchanges information with external devices in the communication network. The external devices in the communication network may be a personal computer that transmits jobs to the image forming apparatus  1 , a server device of a service center, and the like. The service person who maintains the image forming apparatus belongs to the service center. In accordance with the information being managed by the server device, the service person visits the location of installation of the image forming apparatus to be maintained, and then performs maintenance. The communicator  90  is also communicably connected to the indoor hygrometer HY 1 . 
     The internal heater HE 1  is a heater that is disposed below the sheet storage unit  10 , and raises the temperature inside the image forming apparatus  1 , under the control of the control unit  50 . The humidity inside the apparatus decreases with the temperature rise in the apparatus. 
     The indoor hygrometer HY 1  is a humidity detector installed outside the image forming apparatus  1  in the room where the image forming apparatus  1  is installed. The indoor hygrometer HY 1  measures the humidity in the room, and transmits humidity information to the control unit  50  via the communicator  90 . 
     1-2. Structure of the Collection Mechanism 
     Next, the structure of the collection mechanism  100  is described, with reference to  FIG. 1  and  FIG. 3 .  FIG. 3  is a schematic view of the collection mechanism  100 . 
     As shown in  FIG. 2 , the collection mechanism  100  includes: the duct unit  110  that forms an air passage for allowing air containing the ozone generated at the chargers  35  of the image forming units  30 Y,  30 M,  30 C, and  30 K and the toner scattered at the developing parts  32  of the image forming units  30 Y,  30 M,  30 C, and  30 K; and the collector  120  that collects and releases the toner and the ozone from the air flowing in from the duct unit  110 . 
     1-2-1. Structure of the Duct Unit 
     The duct unit  110  includes: suction ducts  111  provided for the respective chargers  35  of the four image forming units  30 Y,  30 M,  30 C, and  30 K; suction ducts  112  provided for the respective developing parts  32  of the image forming units  30 Y,  30 M,  30 C, and  30 K; a common duct  113  that integrates the respective suction ducts  111  and  112 ; assist fans F 1  and F 2 ; and shutter portions SH 1  and SH 2 . 
     The suction ducts  111  are disposed below the developing parts  32  of the respective colors. The inlet port  111   a  of each suction duct  111  is located in the vicinity of the charger  35  of each corresponding color, and sucks the air containing the ozone generated around the charger  35 . 
     The suction ducts  112  are disposed above the developing parts  32  of the respective colors. A duct  32   b  is formed in the developing part  32  of each color. The inlet port of each duct  32   b  is located in the vicinity of the photoreceptor  31  and the developing roller  32   a,  and sucks the air containing the toner scattered around the photoreceptor  31  and the developing roller  32   a.  The inlet port  112   a  of the suction duct  112  of each color is located in the vicinity of the outlet of the duct  32   b  of each corresponding color, and sucks the air containing the toner scattering around the photoreceptor  31  and the developing roller  32   a  via the duct  32   b.    
     The common duct  113  is formed in a hollow rectangular parallelepiped shape extending in the vertical direction. The common duct  113  functions to guide the toner-containing air to the collector  120 , and serves as a receiving unit that allows the collector  120  to be detachably attached to the duct unit  110 . 
     The common duct  113  has four communicating ports capable of connecting the suction ducts  111  and  112  to the side surface facing the four image forming units  30 Y,  30 M,  30 C, and  30 K. A connecting port  113 A for connecting the inlet port  121  of the collector  120  thereto is formed on the surface of the common duct  113  on the side opposite from the side facing the four image forming units  30 Y,  30 M,  30 C, and  30 K. 
     The assist fans F 1  are located in the vicinities of the chargers  35  of the respective colors, and, under the control of the control unit  50 , blows the air in the vicinities of the chargers  35  of the respective colors toward the inlet ports  111   a  by virtue of rotation of an impeller unit (not shown). In this manner, the assist fans F 1  assist the inflow of air at the inlet ports  111   a.  The assist fans F 2  are located in the vicinities of the photoreceptors  31  and the developing rollers  32   a  of the respective colors, and, under the control of the control unit  50 , blows the air in the vicinities of the photoreceptors  31  and the developing rollers  32   a  of the respective colors toward the inlet ports of the ducts  32   b  of the developing parts  32  by virtue of rotation of the impeller unit (not shown). In this manner, the assist fans F 2  assist the inflow of air at the inlet ports  112   a.    
     The shutter portions SH 1  are provided in the inlet ports  111   a  of the respective colors, and, under the control of the control unit  50 , open and close the cross-sectional areas of the air inlet paths of the inlet ports  111   a  of the respective colors. When the shutter portions SH 1  are closed, the air passing through the suction ducts  111  are blocked. When the shutter portions SH 1  are opened, air can pass through the suction ducts  111 . The shutter portions SH 2  are provided in the inlet ports  112   a  of the respective colors, and, under the control of the control unit  50 , open and close the cross-sectional areas of the air inlet paths of the inlet ports  112   a  of the respective colors. When the shutter portions SH 2  are closed, the air passing through the suction ducts  112  are blocked. When the shutter portions SH 2  are opened, air can pass through the suction ducts  112 . 
     As shown in  FIG. 3 , the collection mechanism  100  may include a shielding member  114  in the connecting port  113 A. The shielding member  114  is provided on the lower surface inside the connecting port  113 A, for example. Under the control of the control unit  50 , the shielding member  114  protrudes upward from the lower surface inside the connecting port  113 A, to narrow the cross-sectional area of the connecting port  113 A. The shielding member  114  preferably has such a shape that guides the toner-containing air in a direction along a tangent line of a cyclone unit  122  that will be described later. In such a structure, the direction of the wind generated when the scattered toner is sucked is parallel to a tangent line of the cyclone unit  122  (as indicated by an arrow W 1  in  FIG. 3 ). Thus, the centrifugal force at the cyclone unit  122  becomes greater than that in a case where the direction of the wind is not parallel to a tangent line of the cyclone unit  122  (as indicated by an arrow W 2  in  FIG. 3 ), and separation efficiency can be increased. 
     1-2-2. Structure of the Collector 
     The collector  120  can be detachably attached to the common duct  113 . The collector  120  includes the inlet port  121 , the cyclone unit  122  communicating with the inlet port  121 , a collecting unit  123 , a reversing unit  124 , an airflow path unit  125 , the filter unit  126 , the unusual odor detecting sensor  84 , an outlet port  128 , and a fan F 3  that generates an air flow. 
     The shielding member  114  also preferably has such a shape that guides air toward the top portion of the cyclone unit  122 . For example, the shielding member  114  may have a shape that increases in height in the direction from the suction ducts  111  toward the cyclone unit  122 . In such a structure, the wind generated when the scattered toner is sucked is guided toward the top portion of the cylindrical cyclone unit  122  (as indicated by the arrow W 1  in  FIG. 3 ). Thus, the separation distance becomes longer than that in a case where the wind is not guided toward the top portion of the cyclone unit  122  (as indicated by the arrow W 2  in  FIG. 3 ), and separation efficiency can be increased. 
     The inlet port  121  is a receiving port that receives the toner- and ozone-containing air that has passed through the duct unit  110 . When the collector  120  is attached to the common duct  113 , the inlet port  121  faces the connecting port  113 A of the common duct  113 . As a result, the cyclone unit  122  communicates with the common duct  113  via the inlet port  121 . 
     The cyclone unit  122  communicates with the space inside the common duct  113 , and centrifugally separates the toner from the inflowing air. The cyclone unit  122  is formed in a cylindrical shape, and its axis coincides with the vertical direction (the direction in which gravity acts). This arrangement in which the axis is made to extend in the vertical direction is an optimum arrangement for separating the toner from the air. 
     The air that has entered the cyclone unit  122  flows in a tangential direction of the inner periphery of the cyclone unit  122 . As a result, a swirling flow in which air circulates is generated inside the cyclone unit  122 . The toner in the swirling flow moves in a radial direction because of the centrifugal force that acts when an object circulates. Accordingly, most of the toner is separated from the air (centrifugal separation). The separated toner falls downward due to its own weight, and is stored in the collecting unit  123 . On the other hand, the air enters the reversing unit  124  provided above the cyclone unit  122 . 
     The reversing unit  124  has a shape like a U-shaped pipe, and reverses the air from the cyclone unit  122  upside down, to guide the air to the airflow path unit  125 . 
     The airflow path unit  125  communicates with the reversing unit  124 , and guides the air flowing from the cyclone unit  122  via the reversing unit  124  downward. The filter unit  126  that filters the toner is disposed in the airflow path unit  125 . 
     The filter unit  126  collects the small amounts of toner and ozone contained in the air having passed through the cyclone unit  122 . Thus, the air that has passed through the filter unit  126  is cleaned. It is preferable to use more than one filter unit  126  and stack the filter units  126  in the air flowing direction. With this arrangement, the air cleaning effect becomes greater. For example, the filter units  126  may be a toner dust preventing filter unit  126   a,  an ozone catalyst filter unit  126   b,  and a toner dust preventing filter unit  126   c  that are arranged in this order from the side of the cyclone unit  122 . The filter unit  126  may include an activated carbon filter. The unusual odor components sucked by the chargers  35  of the respective colors are collected by the ozone catalyst filter unit  126   b  (and the activated carbon filter). 
     The unusual odor detecting sensor  84  is provided in the flow path on the downstream side of the filter unit  126 . The outlet port  128  is provided on the opposite side of the airflow path unit  125  from the cyclone unit  122 . The outlet port  128  faces the fan F 3 , and the air that has passed through the filter unit  126  flows out from the outlet port  128  toward the fan F 3 . The fan F 3  functions as an ozone fan that causes ozone to flow in through the inlet port  121 , and as a suction fan that causes scattered toner to flow in through the inlet port  121 . Under the control of the control unit  50 , the fan F 3  rotates the impeller unit to allow air to pass, and is capable of controlling the wind speed of the passing air by increasing or decreasing the rotation speed of the impeller unit. 
     The fan F 3  is disposed above the outlet port  128 . The fan F 3  allows air to flow from the duct unit  110  to the collector  120 . That is, the air sucked by the suction ducts  111  passes through the common duct  113 , the cyclone unit  122 , the reversing unit  124 , the airflow path unit  125 , the filter unit  126 , and the outlet port  128 , and after that, further passes through the fan F 3 , to be released to the outside of the image forming apparatus  1 . 
     A handle  120 A to be gripped when the collector  120  is attached to or detached from the common duct  113  is provided on the surface on the opposite side from the surface on which the inlet port  121  of the collector  120  is formed. 
     1-3. Operation of the Image Forming Apparatus 
     Referring now to  FIG. 4 , operation of the image forming apparatus  1  is described.  FIG. 4  is a flowchart showing the first unusual odor prevention process. 
     In the image forming apparatus  1 , an image forming process for forming an image on a paper sheet is performed in accordance with a job that is input from an external device via the communicator  90  or from the operation display part  70 . Further, in the image forming apparatus  1 , during an image forming process or in a standby state, the control unit  50  causes the collection mechanism  100  to perform a collecting process to collect the toner and the ozone scattered at the image forming part  30  (the image forming units  30 Y,  30 M,  30 C, and  30 K). In this collecting process, the fan F 3  rotates at a normal rotation speed, the assist fans F 1  and F 2  are not operated, and the shutter portions SH 1  and SH 2  are opened, for example. 
     The first unusual odor prevention process to be performed during an image forming process or in a standby state in the image forming apparatus  1  is now described, with reference to  FIG. 4 . Butanol, which is an unusual odor component, is generated by a chemical reaction between ozone and scattered toner in a high-humidity environment when the chargers  35  have a high voltage. The first unusual odor prevention process is a process to take measures beforehand to prevent generation of an unusual odor component in a case where the cause of generation of an unusual odor component has been detected. The first unusual odor prevention process is performed at predetermined intervals, for example. In the image forming apparatus  1 , with the trigger being the elapse of a predetermined period of time during an image forming process and in a standby state, the control unit  50  performs the first unusual odor prevention process in accordance with the first unusual odor prevention program stored in the storage unit  60 . 
     First, the control unit  50  acquires detected information from the detector  80 , and determines whether there is a detected abnormality by determining whether the detected information is equal to or higher than a predetermined threshold value indicating abnormality detection (step S 11 ). More specifically, in step S 11 , the control unit  50  determines whether the detected information acquired from the internal humidity sensor  81  is equal to or higher than a predetermined threshold humidity indicating abnormality detection, determines whether the detected information acquired from the indoor hygrometer HY 1  is equal to or higher than a predetermined threshold humidity indicating abnormality detection, determines whether the detected information acquired from the ozone sensor  82  of each color is equal to or higher than a predetermined threshold ozone concentration indicating abnormality detection, determines whether the detected information about the chargers  35  acquired from the voltage measuring unit of each color is equal to or higher than a predetermined threshold voltage indicating abnormality detection, determines whether the detected information acquired from the particle counter  83  of each color is equal to or higher than a predetermined threshold toner particle value, and determines whether the detected information acquired from the unusual odor detecting sensor  84  is equal to or higher than a predetermined threshold butanol concentration indicating abnormality detection. If any of the detected information is equal to or higher than the corresponding threshold value, the control unit  50  determines that there is a detected abnormality. If all the detected information is lower than the threshold values, it is determined that there is a detected abnormality. 
     If there is no detected abnormality (step S 11 : NO), the first unusual odor prevention process comes to an end. If there is a detected abnormality (step S 11 : YES), the control unit  50  determines whether the type of the abnormality detection is related to a high-humidity environment (a humidity abnormality detected by the internal humidity sensor  81  or the indoor hygrometer HY 1 ) (step S 12 ). In the case of a high-humidity environment (step S 12 : YES), the control unit  50  determines the detector that has detected the abnormality (step S 13 ). 
     In a case where the detector that has detected the abnormality is the internal humidity sensor  81  (step S 13 : internal humidity sensor), the control unit  50  performs a process suitable for an abnormality detected by the internal humidity sensor  81  (step S 14 ). In step S 14 , the control unit  50  separates the fixing roller  43  and the pressure roller  44  from each other and activates the air separating unit  45  to blow warm air to the chargers  35 , and also activates the internal heater HE 1  to lower the internal humidity, for example. 
     In a case where the detector that has detected the abnormality is the indoor hygrometer HY 1  (step S 13 : indoor hygrometer), the control unit  50  performs a process suitable for an abnormality detected by the indoor hygrometer HY 1  (step S 15 ). In step S 15 , to indicate a warning to the user, the control unit  50  causes the operation display part  70  to display warning information to the effect that the indoor humidity is high, and there is a possibility of generation of unusual odor (butanol), for example. The user reads the warning information, and can lower the humidity in the room by driving the air-conditioner in the room or ventilating the room. 
     If the detected abnormality is not related to a high-humidity environment (step S 12 : NO), the control unit  50  determines whether the type of the detected abnormality is related to ozone (an ozone abnormality detected by the ozone sensor  82  or an abnormality detected by a voltage measuring unit in the charge pressure of the charger  35 ) (step S 16 ). In the case of an ozone high-humidity environment (step S 16 : YES), the control unit  50  determines the detector that has detected the abnormality (step S 17 ). 
     In a case where the detector that has detected the abnormality is the ozone sensor  82  (step S 17 : ozone sensor), the control unit  50  performs a process suitable for an abnormality detected by the ozone sensor  82  (step S 18 ). In step S 18 , to reduce the generation of ozone, the control unit  50  lowers the pages per minute (PPM: the number of pages printed per minute) in image formation, for example. To have the ozone sucked quickly and cause the ozone catalyst filter unit  126   b  to collect the ozone, the control unit  50  increases the wind speed of the fan F 3 , switches on operation of the assist fans F 1 , opens the shutter portions SH 1 , and closes the shutter portions SH 2 . It is preferable to switch on the operation of the assist fans F 1  and open/close the shutter portions SH 1  and SH 2  in accordance with the color in which the abnormality has been detected. 
     In a case where the detector that has detected the abnormality is a voltage measuring unit (step S 17 : voltage measuring unit), the control unit  50  performs a process suitable for an abnormality detected by a voltage measuring unit (step S 19 ). In step S 19 , if the charge pressure measured by the voltage measuring unit is equal to or higher than a certain level (a predetermined threshold value), the control unit  50  stops the image forming operation, to lower the charge pressure of the charger  35 , for example. 
     If the detected abnormality is not related to ozone (step S 16 : NO), the control unit  50  determines whether the type of the detected abnormality is a scattered toner abnormality or an unusual odor abnormality (step S 20 ). In the case of a scattered toner abnormality (step S 20 : scattered toner), the control unit  50  performs a process suitable for an abnormality detected by the particle counter  83  (step S 21 ). In step S 21 , to reduce the scattered toner, the control unit  50  switches the image formation mode to a low-coverage mode for reducing the amount of toner on paper sheets, and reduces the number of developing operations by lowering the PPM, for example. To have the scattered toner sucked quickly and cause the collector  120  to collect the scattered toner, the control unit  50  also increases the wind speed of the fan F 3 , switches on operation of the assist fans F 2 , opens the shutter portions SH 2 , and closes the shutter portions SH 1 . It is preferable to switch on the operation of the assist fans F 2  and open/close the shutter portions SH 1  and SH 2  in accordance with the color in which the abnormality has been detected. 
     In the case of an unusual odor abnormality (step S 20 : unusual odor), the control unit  50  performs a process suitable for an abnormality detected by the unusual odor detecting sensor  84  (step S 22 ). In step S 22 , to remove the unusual odor component with the filter unit  126  (the ozone catalyst filter unit  126   b  (and the activated carbon filter)), for example, the control unit  50  predicts the timing to exchange the filter unit  126  (or the ozone catalyst filter unit  126   b  (and the activated carbon filter)) with a new one, causes the operation display part  70  to display the predicted information, and transmits, by e-mail, information about the exchange timing to a service person (or to the server device of the service center) via the communicator  90 . The service person visits the place of installation of the image forming apparatus  1  as the transmission source of the e-mail, and exchanges the filter unit  126  (or the ozone catalyst filter unit  126   b  (and the activated carbon filter)) with a new one. 
     The control unit  50  then acquires detected information from the detector  80 , and determines whether the abnormality detection has recovered by determining whether the detected information has recovered from a value equal to or higher than a predetermined threshold value indicating abnormality detection (step S 23 ). More specifically, in step S 23 , regarding the detector that has detected the abnormality, the control unit  50  determines whether the detected information acquired from the internal humidity sensor  81  has recovered to a lower value than the predetermined threshold humidity indicating abnormality detection, determines whether the detected information acquired from the ozone sensor  82  of each color has recovered to a lower value than the predetermined threshold ozone concentration indicating abnormality detection, determines whether the detected information about the chargers  35  acquired from the voltage measuring unit of each color has recovered to a lower value than the predetermined threshold voltage indicating abnormality detection, determines whether the detected information acquired from the particle counter  83  of each color has recovered to a lower value than the predetermined threshold toner particle value, or determines whether the detected information acquired from the unusual odor detecting sensor  84  has recovered to a lower value than the predetermined threshold butanol concentration indicating abnormality detection. 
     If there is no abnormality detection recovery (step S 23 : NO), the process moves on to step S 12 . If there is an abnormality detection recovery (step S 23 : YES), the control unit  50  stops the processing being performed in step S 14 , S 15 , S 18 , S 19 , S 21 , or S 22  (step S 24 ), and ends the first unusual odor prevention process. 
     As described above, according to this embodiment, the image forming apparatus  1  includes the chargers  35  that charge the photoreceptors  31 , and the developing parts  32  that develop toner image son the charged and exposed photoreceptors  31 . The image forming apparatus  1  also includes: the detector  80  that detects humidity, ozone generated from the chargers  35 , and toner scattered from the developing parts  32 ; and a processor (the control unit  50 , the shutter portions SH 1  and SH 2 , the assist fans F 1  and F 2 , the fan F 3 , the air separating unit  45 , and the operation display part  70 ) that reduces the humidity, the ozone, or the scattered toner equal to or higher than a predetermined threshold, when at least one of the detected humidity, ozone, and scattered toner is equal to or higher than a predetermined threshold value that is set in advance. 
     With this structure, it is possible to prevent generation of unusual odor in advance, and unusual odor is not removed after generation thereof. Thus, it is possible to lower the labor costs and the component costs required in removing unusual odor. 
     In a process of lowering humidity, the control unit  50  also causes the internal heater HE 1  to heat the inside of the image forming apparatus  1 , causes the air separating unit  45  to blow warm air to the chargers  35 , or causes the operation display part  70  to display information about a result of detection. Accordingly, humidity can be automatically or manually lowered (through room temperature and humidity adjustment conducted by the user), and generation of unusual odor can be prevented in advance. 
     Further, the detector  80  (the ozone sensor  82 , and the voltage measuring units of the chargers  35 ) detects the ozone generated from the chargers  35  and the voltage of the chargers  35 . In a case where the detected ozone or the detected voltage becomes equal to or higher than a predetermined threshold value, the control unit  50  performs a process of reducing the ozone. Thus, generation of ozone can be accurately detected. 
     Further, in a process of reducing ozone, the control unit  50  reduces the number of times (per unit time) charging (discharging) is performed by the chargers  35 , to lower the voltage (by stopping image formation). Accordingly, generation of ozone can be effectively reduced, and generation of unusual odor can be effectively prevented. 
     The image forming apparatus  1  also includes the collection mechanism  100  that collects ozone. In a process of reducing ozone, the control unit  50  performs a process of increasing the amount of ozone to be captured by the collection mechanism  100 , by increasing the wind speed of the fan F 3 , driving the assist fans F 1 , and closing the shutter portions SH 2 . Accordingly, generation of ozone can be more effectively reduced, and generation of unusual odor can be more effectively prevented. 
     The control unit  50  also performs a process of reducing the amount of toner at the developing parts  32  at a time of image formation, as a process of reducing scattered toner. Accordingly, generation of scattered toner can be effectively reduced, and generation of unusual odor can be effectively prevented. 
     The image forming apparatus  1  also includes the collection mechanism  100  that collects toner. In a process of reducing scattered toner, the control unit  50  performs a process of increasing the amount of toner to be captured by the collection mechanism  100 , by increasing the wind speed of the fan F 3 , driving the assist fans F 2 , and closing the shutter portions SH 1 . Accordingly, generation of scattered toner can be more effectively reduced, and generation of unusual odor can be more effectively prevented. 
     The unusual odor detecting sensor  84  of the detector  80  detects unusual odor. In a case where the detected unusual odor is equal to or higher than a predetermined threshold value that is set in advance, the control unit  50  performs a process of notifying the service person of the timing to exchange the filter unit  126  with a new one through transmission to the server device of the service center via the communicator  90 , and notifying the user of the exchange timing through display on the operation display part  70 . Thus, the user and the service person can be prompted to perform maintenance such as exchanging the filter unit  126  with a new one without fail. 
     The control unit  50  also performs a process of reducing humidity, ozone, or scattered toner. In a case where the reduced humidity, ozone, or scattered toner is lower than the corresponding predetermined threshold value, the control unit  50  stops the process of reducing humidity, ozone, or scattered toner. Accordingly, in a case where humidity, ozone, or scattered toner has been appropriately reduced, the state of the image forming apparatus  1  can be promptly recovered. 
     2. Modification 
     A modification of the above embodiment is now described, with reference to  FIG. 5A ,  FIG. 5B  and  FIG. 6 . 
     As in the above embodiment, an image forming apparatus  1  is used as an apparatus configuration in this modification. However, the storage unit  60  stores a prediction judgment table T 1  and a process table T 2 , and also stores a second unusual odor prevention program, instead of the first unusual odor prevention program. 
     2-1. Configurations of the Tables 
     Referring now to  FIG. 5A  and  FIG. 5B , the prediction judgment table T 1  and the process table T 2  stored in the storage unit  60  are described.  FIG. 5A  is a diagram showing the prediction judgment table T 1 .  FIG. 5B  is a diagram showing the process table T 2 . 
     As shown in  FIG. 5A , the prediction judgment table T 1  includes information about the abnormality detection patterns of Examples 1 to 12 as case examples corresponding to the types of detection to be performed by the detector  80 , and information about presence/absence of predictions for unusual odor generation in the respective examples. 
     In a case where the detection type is “humidity”, the control unit  50  determines whether detected information acquired from the internal humidity sensor  81  is equal to or higher than a predetermined threshold humidity indicating abnormality detection. If the detected information is equal to or higher than the predetermined threshold value, “(abnormality) detected” is shown in the table. In a case where the detection type is “ozone”, the control unit  50  determines whether detected information acquired from the ozone sensor  82  of each color is equal to or higher than a predetermined threshold ozone concentration indicating abnormality detection. If the detected information is equal to or higher than the predetermined threshold value, “(abnormality) detected” is shown in the table. 
     In a case where the detection type is “scattered toner”, the control unit  50  determines whether detected information acquired from the particle counter  83  of each color is equal to or higher than a predetermined threshold toner particle value indicating abnormality detection. If the detected information is equal to or higher than the predetermined threshold value, “(abnormality) detected” is shown in the table. In a case where the detection type is “discharge amount”, the control unit  50  calculates the discharge amount of each charger  35  from detected information about each charger  35  acquired from the voltage measuring units of the respective colors, and determines whether the calculated discharge amount is “high” or is equal to or higher than a predetermined threshold discharge amount indicating abnormality detection, or determines whether the calculated discharge amount is “low” or is lower than the predetermined threshold discharge amount. 
     In the prediction judgment table T 1 , presence/absence of a prediction for unusual odor generation is set, in accordance with a pattern that shows presence/absence of a detected abnormality of the detection type “humidity”, presence/absence of a detected abnormality of the detection type “ozone”, presence/absence of a detected abnormality of the detection type “scattered toner”, and “high”/“low” in the detection type “discharge amount”. 
     As shown in  FIG. 5B , the process table T 2  shows the effectiveness of unusual odor prevention by Processes P 1  to P 9  in Examples 1 to 12 as the case examples shown in the prediction judgment table T 1 . “⊙” in effectiveness indicates that the effectiveness is very high. “∘” in effectiveness indicates that there is effectiveness. “x” in effectiveness indicates that the effectiveness is poor, and the corresponding process is not to be selected and performed. 
     Process P 1  is a process of reducing the discharge time of the high voltage of the charger  35  of each color of the image forming part  30 . Process P 2  is a process of reducing the load timing of the high voltage of the charger  35  of each color of the image forming part  30 . Process P 3  is a process of lowering the toner density and reducing the amount of scattered toner by controlling the developing part  32  of each color, and is performed in a low-coverage mode, for example. Process P 4  is a process of setting a toner refresh mode and reducing the amount of scattered toner, by controlling the developing part  32  of each color. The toner refresh mode is a mode in which the toner and the carrier in the developing parts  32  are stirred and refreshed. 
     Process P 5  is a process of lighting up and lowering the humidity in the image forming apparatus  1 , by controlling the internal heater HE 1 . Process P 6  is a process of causing the operation display part  70  to display information about a prediction for unusual odor generation, by controlling the operation display part  70 . Process P 7  is a process of predicting the timing to exchange the filter unit  126  with a new one, and causing the operation display part  70  to display the predicted exchange timing. 
     Process P 8  is a process of causing the operation display part  70  to display information indicating necessity of maintenance of the developer (the toner and the carrier) in the developing part  32  and the charger  35  of the color in which an abnormality has been detected, by controlling the operation display part  70 . Process P 9  is a process of transmitting information indicating the necessity of maintenance of the developer in the developing part  32  and the charger  35  of the color in which an abnormality has been detected, to the server device of the service center via the communicator  90 , by controlling the operation display part  70 . 
     The patterns of Processes P 1  to P 9  in the process table T 2  are merely examples, and Processes P 1  to P 9  do not necessarily have these patterns. Further, the patterns of Processes P 1  to P 9  in the process table T 2  may be changed in response to an operation input by the user, a service person, or the like via the operation display part  70 , or may be changed or set depending on conditions such as time slots. 
     2-2. Operation of the Image Forming Apparatus 
     Referring now to  FIG. 6 , operation of the image forming apparatus  1  is described.  FIG. 6  is a flowchart showing a second unusual odor prevention process. 
     The second unusual odor prevention process to be performed during an image forming process or in a standby state in the image forming apparatus  1  is now described, with reference to  FIG. 6 . The second unusual odor prevention process is a process to of taking measures beforehand to prevent generation of an unusual odor component in a case where the cause of generation of an unusual odor component has been detected. The second unusual odor prevention process is performed at predetermined intervals, for example. In the image forming apparatus  1 , with the trigger being the elapse of a predetermined period of time during an image forming process and in a standby state, the control unit  50  performs the second unusual odor prevention process in accordance with the second unusual odor prevention program stored in the storage unit  60 . 
     First, the control unit  50  refers to the prediction judgment table T 1  stored in the storage unit  60 , to acquire detected information from the detector  80 . The control unit  50  then determines whether to predict generation of unusual odor, by determining whether the pattern of abnormality detection and the fluctuation of the discharge amount of the respective types of detection in the detected information corresponds to a pattern (a case example) shown in the prediction judgment table T 1  (step S 21 ). More specifically, in step S 21 , the control unit  50  generates a pattern indicating that there is a detected abnormality and the discharge amount is high or low, in accordance with detected information acquired from the internal humidity sensor  81 , the ozone sensor  82 , and the particle counter  83 , as described above. The control unit  50  then determines whether there is a prediction for unusual odor generation, by comparing the generated pattern with the patterns in the prediction judgment table T 1 . 
     If unusual odor generation is not predicted (step S 21 : NO), the second unusual odor prevention process comes to an end. If unusual odor generation is predicted (step S 21 : YES), the control unit  50  refers to the process table T 2  stored in the storage unit  60 , refers to the process corresponding to the pattern (case example) predicted in step S 21  among Processes P 1  to P 9 , refers to the prediction selected in step S 21  from among Processes P 1  to P 9 , and determines the process pattern corresponding to the pattern (case example) predicted in step S 21  (step S 22 ). 
     The control unit  50  then performs a process corresponding to the process pattern of the process determined in step S 22  (step S 23 ). In step S 23 , the processes with “⊙” and “∘” in the determined process pattern (case example) in the process table T 2  are performed, for example. However, the processes to be performed are not limited to such processes. 
     In the same manner as in step S 21 , the control unit  50  then acquires the detected information from the detector  80  in accordance with the detection type of abnormality detection (“high” in the discharge amount) in the case example predicted in step S 21 , acquires the abnormality detection for the respective detection types and the levels (high/low) of the discharge amounts in the detected information, and determines whether the abnormality detection (“high” in the discharge amount) has recovered from step S 21  (step S 24 ). If the abnormality detection (“high” in the discharge amount) has not recovered (step S 24 : NO), the process moves on to step S 23 . 
     If the abnormality detection (“high” in the discharge amount) has recovered (step S 24 : YES), the control unit  50  stops the processing performed in step S 23  (step S 25 ), and ends the second unusual odor prevention process. 
     In this modification, in a case where the filter cost of the filter unit  126  is $10, the machine durability of the image forming apparatus  1  is one million pages, and the regular filter exchange timing is 100,000 pages, it is necessary to exchange filter units nine times within the machine endurance (the first one is mounted at the time of manufacture at the factory), and the labor cost is $90 (=$10/piece×9 exchanges). In a case where the amount of generated unusual odor can be reduced 30% by preliminary abnormality detection of this modification, the number of exchanges decreases to eight, and the labor cost becomes $80. Thus, a $10 reduction in the labor cost is achieved. 
     As described above, according to this modification, it is possible to prevent generation of unusual odor in advance, and unusual odor is not removed after generation thereof, as in the above embodiment. Thus, it is possible to lower the labor costs and the component costs required in removing unusual odor. 
     In a process of reducing ozone, the control unit  50  also reduces the charging (discharging) time and the number of times (per unit time) charging (discharging) is performed in the chargers  35 , to reduce the ozone to be generated. Accordingly, generation of ozone can be effectively reduced, and generation of unusual odor can be effectively prevented. 
     The control unit  50  also performs a refreshing process for the developing parts  32  as a process for reducing scattered toner. Accordingly, generation of scattered toner can be effectively reduced, and generation of unusual odor can be effectively prevented. 
     In a case where the discharge amount corresponding to the detected voltage of the charger  35  is equal to or higher than a predetermined threshold value, the control unit  50  also performs a process of reducing ozone. Thus, generation of ozone can be accurately detected. 
     The control unit  50  also notifies the user of a result of detection and information about necessity of maintenance as information based on a result of detection of humidity, ozone, or scattered toner, through display on the operation display part  70 . Alternatively, the control unit  50  notifies the service person of such information through transmission to the server device of the service center via the communicator  90 . Thus, the user and the service person can be prompted to perform maintenance of the image forming apparatus  1  without fail. 
     The above descriptions of the embodiment and the modification are about examples of preferred image forming apparatuses according to embodiments of the present invention, and do not limit the present invention. For example, the embodiment and the modification may be combined as appropriate. 
     Further, in the above described embodiment and the modification, the image forming apparatus  1  includes the image forming part  30  of the four colors Y, M, C, and K, and is designed to perform color image formation. With respect to the four colors Y, M, C, and K, the image forming apparatus  1  detects ozone (including the voltage of the chargers  35 ) and toner. If an abnormality is detected, the image forming apparatus  1  performs a process of reducing humidity, ozone, or scattered toner, using assist fans shutters, and the like. However, the image forming apparatus  1  is not necessarily designed in this manner. For example, ozone (including the voltage of the chargers  35 ) and toner may be detected with respect to at least one color (such as black, which is frequently used) of the four colors, and, when an abnormality is detected, a process of reducing humidity, ozone, or scattered toner may be performed with assist fans, shutters, and the like. Alternatively, the image forming apparatus  1  may include a black image forming part  30  to perform monochrome image formation, detect the ozone and the toner corresponding to black, and perform a process of reducing humidity, ozone, or scattered toner when an abnormality is detected. 
     Further, in the above described embodiment and the modification, in a case where the amount of detection performed by the detector  80  becomes lower than a predetermined threshold value after a process of preventing unusual odor is performed, the unusual odor prevention process is stopped. However, this operation is not necessarily performed. For example, after Process P 8  is performed, when the exchange of the filter unit  126  with new one is completed, the control unit  50  may stop the display of the information about the necessity of maintenance on the operation display part  70 . Alternatively, after Process P 9  is performed, and maintenance by a service person is completed, the control unit  50  may stop the transmission of the information about the necessity of maintenance to the server device of the service center via the communicator  90 . 
     Further, at the time of maintenance, the control unit  50  may cause the operation display part  70  to display the number of times action (process execution) has been taken after a prediction. 
     Further, in the above described embodiment and the modification, the detector  80  detects humidity, ozone, and scattered toner, but the present invention is not limited to this. For example, the image forming apparatus  1  may detect at least one of humidity, ozone, and scattered toner with the detector  80 , and perform a process of preventing unusual odor by reducing humidity, ozone, and scattered toner in accordance with the result of the detection. 
     Further, the control unit  50  of each image forming apparatus  1  may transmit information about the cause of unusual odor and the occurrence status of the unusual odor in at least one image forming apparatus  1 , to the server device of the service center via the communicator  90 . The server device is then caused to gather the information. The received information is analyzed in the server device, so that information about the unusual odor generated situation in each area and predictions for unusual odor generation is generated and provided. In accordance with the information about predictions, the number of filter units  126  to be produced and distributed are adjusted so as to smoothly respond to the market demand. 
     Further, the image forming apparatus  1  may also include an image calibrating unit on the downstream side of the fixing unit  40 , and the image calibrating unit reads an image formed on a paper sheet and calibrates each component of the image forming apparatus  1 . In a case where the image level of an image read by the image calibrating unit is equal to or higher than a predetermined normal image level, the control unit  50  may predict unusual odor and perform a process of taking a measure against the unusual odor. In a case where the image level is lower than the predetermined normal image level, the control unit  50  may transmit maintenance necessity information to the server device of the service center via the communicator  90 . In a case where the image calibrating unit is not provided, the user may visually determine the image level of an image formed on a paper sheet. If the image level is lower than the predetermined normal image level, the control unit  50  may transmit the maintenance necessity information to the server device of the service center via the communicator  90 , in accordance with an input from the user via the operation display part  70 . 
     Further, modifications may be made to the specific configurations and the specific operations of the respective components constituting the image forming apparatus  1  in the above embodiment, without departing from the scope of the present invention. 
     Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.