Abstract:
A device for monitoring the status or condition of a filter assembly for an imaging device which employs an optical sensing device to monitor a concentration of toner particles. In one embodiment, the optical sensing device monitors a concentration of toner particles captured in a filter assembly within an electrostatic imaging device. The optical sensing device is connected to an imaging device controller. An output connected to the controller displays data representative of a degree to which the filter element is clogged by toner particulate.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical Field  
           [0002]    The present invention relates generally to imaging devices and more particularly to a device for monitoring the condition of a toner filter assembly for an imaging device.  
           [0003]    2. Background Art  
           [0004]    The process of electrostatic imaging, whether in an electrophotographic copier, a laser printer, or another imaging device, typically involves the light-directed distribution of electrostatic charge over the surface of a photoconductor. A developing system deposits toner particles on the photoconductor and said toner particles are in turn deposited as an image onto a sheet of paper. In order to prolong the life of the system, imaging systems typically use replaceable assemblies including consumable elements of the system such as toner and wear-sensitive elements including developing systems and photoconductors.  
           [0005]    During the imaging process, toner particles may become airborne and deposit undesirably within the system or may escape the imaging system entirely. Loose toner can create print quality problems, clog replaceable and non-replaceable moving parts within the system, and contaminate the environment outside the imaging system. Attempting to clean loose toner out of the device is difficult and may damage fragile parts within the system. An imaging device may therefore include a filter assembly which removes toner particles from the air circulating within the system. Similarly, a replaceable toner cartridge or developer assembly may also include a filter assembly which removes toner particles from the air circulating within the system. A loss of toner may also occur if elements within a toner cartridge or developer assembly, such as the toner seals, break. Breakage is more common when the toner within the toner cartridge or developer assembly is refilled or, if many images requiring little toner are printed, and the lifetime of the moving parts within the developer assembly expires before toner levels dwindle. This may lead to breakage of the toner seals or other parts. Toner spillage due to breakage rapidly clogs the filter assembly. Over the life of a toner cartridge or developer assembly, toner can clog the filter assembly even without a breakage event. In either case, the clogging of the filter assembly may go unnoticed by the user, inadvertently degrading the performance of the imaging device.  
           [0006]    Therefore, it may be advantageous to provide a device for monitoring the condition of imaging device air/toner filter assemblies. It may also be advantageous to prevent usage of the imaging system if the toner filter assembly is clogged. There may also be advantage in providing for a qualitative estimate of filter life that may also aid in detecting toner seal leakage or breakage if filter blockage increases more quickly than normal.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed to a device for monitoring an air transport efficiency of an air/toner filter element for an imaging device. The device employs an optical sensing device to monitor a concentration of toner particles in the filter element. The air/toner filter assembly may be installed in a wall of the imaging device housing or in the alternative it may be incorporated directly in the toner cartridge or developer assembly. In a preferred embodiment, the optical sensing device monitors a concentration of toner particles captured in a filter element. The optical sensing device is connectable to an output or display for displaying data representative of an air transport efficiency of the filter element. The output may indicate that the filter exhibits a predetermined condition, for instance that the filter element is functioning with an air transport efficiency of a measured percentage of full efficiency. According to the present invention, the optical sensing device determines filter status by detecting the optical characteristics of the filter. A relatively clean filter will exhibit greater transmission of light indicating a relatively greater air transport efficiency. Conversely, a clogged filter will be darker and more opaque due to the toner trapped within it indicating a relatively lesser air transport efficiency.  
           [0008]    In a preferred embodiment of the invention, the optical sensing device is electrically connected to an imaging device controller. When a condition which indicates clogging of the filter is detected by the optical sensing device, the controller may disable the imaging device to prevent inadvertent use of a defective toner cartridge assembly. Additionally, or in the alternative, the imaging device controller output may enable a signal in the form of a sensory output, i.e. a visual or audible signal. Alternately, the imaging device output from the controller may be in the form of a message displayed on a video output device of an attached or networked computer. This obviates the need for the user to inspect or monitor the optical sensing device directly.  
           [0009]    In one embodiment of the invention, the optical sensing device includes an optical element which measures the amount of light that can pass through the filter, determining its translucency. In another embodiment of the invention, the optical monitor measures the reflectivity, or lightness and darkness, of the filter surface. An optical element senses the degree of blockage of the filter as a function of the amount of light being sensed by the optical element. Alternatively, the optical sensing device may simply sense and determine a binary pass/no-pass determination, once again, as a function of the amount of light being sensed by the optical element.  
           [0010]    An optical sensor device may operate based on a change in reflectance of light from a source to a receptor. For sensor applications, photodetector arrays require the objects they sense to be illuminated by some means. An illumination source is directed at an object, in this case the filter element, and the sensing device is positioned relative to the illumination source and the filter element to permit sensing of either the amount of light that passes through the filter or, in the alternative, the sensing device senses reflectivity of an illuminated surface of the filter element. The optical filter monitor may sense both the level and the rate of filter blockage. If the filter begins to plug quickly, it can be assumed that excessive toner is leaking from the cartridge through the seals and the imaging device may be disabled before excessive toner is released into the internals of the printer/imaging device.  
           [0011]    The present invention consists of the parts hereinafter more fully described, illustrated in the accompanying drawings and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions and minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a schematic representational diagram of an electrophotographic imaging device connected to a personal computing device;  
         [0013]    [0013]FIG. 2 is a representational schematic cutaway view of an electrophotographic imaging device including a developer assembly and a device for monitoring a developer assembly filter element;  
         [0014]    [0014]FIG. 3 is a representational schematic cutaway view of an electrophotographic imaging device including a developer assembly and a device for monitoring a developer assembly filter element; and  
         [0015]    [0015]FIG. 4 is a representational schematic cutaway view of an electrophotographic imaging device including a toner cartridge assembly and a device for monitoring a filter element. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Imaging device  10  is shown in FIG. 1 connected to personal computer  50 . Personal computer  50  is connected to imaging device  10  through cable  51 . Imaging device  10  includes controller  11  which controls the various operating functions of imaging device  10  including print engine  12 . Power supply  13  provides DC electrical current to various components of imaging device  10 . Display  16  provides a visual signaling device for displaying information relating to function and status of various components of imaging device  10 . Personal computer  50  includes processing device  52 . Video output device  53  is connected to personal computer  50  by cable  54 . It should be noted that the connection between personal computer  50  and imaging device  10  and personal computer  50  and video output device  53  is not limited to parallel connection and could just as well be through a serial cable connection, network connection, a remote connection via a telecommunication link, an infrared link, a radio frequency link, or the like.  
         [0017]    Referring to FIGS. 2 and 3, imaging device  10  is enclosed within housing  45  and includes controller  11  which controls various functions of imaging device  10 . Power supply  13  provides power to imaging device  10  including controller  11 . Print engine  12  comprises in part scanning laser  17 , producing laser beam B, developer assembly  20 , transfer drum  14  and charging roller  15 . Scanning laser  17  emits laser beam B as a scanning sequence of impulses which correspond to processed information input to imaging device  10 . Laser beam B is directed at toner cartridge drum  22 .  
         [0018]    As shown in FIGS. 2 and 3, developer assembly  20  includes housing  21  enclosing toner cartridge drum  22  and toner reservoir  23 . Developing drum  29  transfers toner T to surface  24  of toner cartridge drum  22 . Media M is transported through imaging device  10  by transport rollers  37 A and  37 B. Toner T is transferred to media M at nip  38  located between transfer drum  14  and toner cartridge drum  22 . Toner T is fused to media M between fuser roller  41  and pressure roller  42 . Primary seals  34 A and  34 B inhibit passage of toner T past developing drum  29 . Seals  25 A and  25 B and  26 A and  26 B inhibit the passage of airborne toner AT at the interface with toner cartridge drum  22 . Charging roller  15  provides an electromotive potential to surface  24  of toner cartridge drum  22 .  
         [0019]    Filter element  30  is installed in outer wall  32  of housing  21 . Air may transfer from internal chamber  31  of toner cartridge assembly  20  either under ambient air pressure or under a pressure differential. Airborne toner AT is removed from air passing through filter element  30 .  
         [0020]    Filter monitoring device  35  includes illumination source  36  which is connected to controller  11  and directed at surface  33  of filter element  30 . Filter monitoring device  35  also includes optical sensor  40  shown connected to controller  11 . Data D representative of a condition of filter element  30  may be displayed at imaging device display  16 .  
         [0021]    [0021]FIG. 2 shows optical sensor  40  located in housing  21  and connected to controller  11 . Illumination source  36  is connected to controller  11  and directed at surface  33  and optical sensor  40  through filter element  30 . Controller  11  includes algorithm  18 A for determining the condition of filter element  30  as a function of the amount of light L passing through filter element  30  to optical sensor  40  and generating data D representative of a condition of filter element  30  for display at imaging device display  16 .  
         [0022]    [0022]FIG. 3 shows both illumination source  36  and optical sensor  40  located external to housing  21 . FIG. 3 also shows illumination source  36  and optical sensor  40  configured as an integral unit. Illumination source  36  is connected to controller  11  and directed at surface  33  of filter element  30 . Optical sensor  40  senses light reflected from surface  33  of filter element  30 . Controller  11  includes algorithm  18 B for determining the condition of filter element  30  as a function of the amount of light L passing through filter element  30  to optical sensor  40  and generating data D representative of a condition of filter element  30  for display at imaging device display  16 .  
         [0023]    Referring to FIG. 4, imaging device  110  includes controller  111  enclosed within housing  112 . Controller  111  controls various functions and of imaging device  110  including print engine  119 . Power supply  113  provides power to imaging device  110  including controller  111 . Imaging device  110  comprises in part scanning laser  117 , producing laser beam B as a scanning sequence of impulses which correspond to processed information input to imaging device  110 . Laser beam B is directed at surface  124  of photoconductor  122 . Imaging device  110  also includes transfer drum  114  and charging roller  115 .  
         [0024]    As shown in FIG. 4, imaging device  110  includes toner cartridge assembly  120  including housing  123  and developing drum  129 . Developing drum  129  transfers toner T to surface  124  of photoconductor  122 . Media M is transported through imaging device  110  by transport rollers  125 A and  125 B. Toner T is transferred to media M at nip  128  located between transfer drum  114  and photoconductor  122 . Toner T is fused to media M between fuser roller  126  and pressure roller  127 . Primary seals  134 A and  134 B inhibit passage of toner T past developing drum  129 . Charging roller  115  provides an electromotive potential to surface  124  of photoconductor  122 .  
         [0025]    Filter element  130  is shown installed in housing  112  of imaging device  110 . Air transfers from internal chamber  131  of imaging device  110  either under ambient air pressure or under a pressure differential. Airborne toner AT is removed from air passing through filter element  130 . Optical sensor  135  includes an optical sensor connected to controller  111 . Optical sensor  135  senses ambient light L through filter element  130 . Data D representative of a condition of filter element  130  may be displayed at imaging device display  116 . Controller  111  includes algorithm  118 A for determining the condition of filter element  130  as a function of the amount of light L passing through filter element  130  to optical sensor  135 .  
         [0026]    While this invention has been described with reference to the detailed embodiments, this is not meant to be construed in a limiting sense. Various modifications to the described embodiments as well as the inclusion or exclusion of additional embodiments will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.