Abstract:
A method and apparatus for controlling conditions in a printer that includes a print engine that is operative upon an article to print marks upon the article. Sensors are provided for detecting relative humidity and temperature within a moving airstream in the printer. A controller in the printer determines if the detected relative humidity within the apparatus falls within a range of acceptable relative humidities and the detected temperature within the apparatus falls within a range of acceptable temperatures. The range of acceptable relative humidities and acceptable temperatures defines a predetermined target area. When outside the range of the predetermined target area a determination is made of needed minimal adjustments to bring the temperature and humidity within the target area. Subject to such a determination, mist and/or heating of the airstream are provided to implement the needed adjustments.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is related to U.S. application Ser. No. ______ filed by the same inventors on even date herewith and entitled “Printing Apparatus and Method With Improved Control of Airflow.” 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to printer or copier apparatus and methods and more particularly to the control of temperature and humidity in the apparatus.  
       BACKGROUND OF THE INVENTION  
       [0003]     In printing apparatus generally and more particularly of interest to electrophotography or xerography, there is a need to provide control of temperature and humidity within the copier or printer machine in order to provide for optimum performance and ensure image quality. Heretofore, control of temperature and/or humidity was provided by employing individual sensors for each of humidity and temperature in the machine and controlling temperature of the certain component that was particularly critical, such as a photoconductor or xerographic imaging drum or belt, and controlling humidity at a different locations such as at the development station. Each is controlled to a particular set point. A problem with such an approach is that it is relatively energy inefficient and thus increases cost of production and operation of the machine. The other large printing machines employ expensive refrigeration units which also adds to the cost and energy use of the machine.  
       SUMMARY OF THE INVENTION  
       [0004]     The invention is directed to a low-cost solution for control of temperature and humidity in a printer. In accordance with a first aspect of the invention there is provided a printer apparatus comprising a print engine that is operative upon an article to be printed to impart markings upon the article; a sensor for detecting humidity within the printer apparatus; a sensor for detecting temperature within the printer apparatus; and a controller for determining if the detected humidity within the apparatus falls within a range of acceptable humidities and the detected temperature within the apparatus falls within a range of acceptable temperatures wherein the range of acceptable humidities and acceptable temperatures defines an area of setpoints of acceptable humidities and temperatures.  
         [0005]     In accordance with a second aspect of the invention, there is provided a method of controlling conditions in a printer apparatus that includes a print engine that is operative upon an article to print marks upon the article, the method comprising detecting humidity within the printer apparatus; detecting temperature within the printer apparatus; and determining if the detected humidity within the apparatus falls within a range of acceptable humidities and the detected temperature within the apparatus falls within a range of acceptable temperatures wherein the range of acceptable humidities and acceptable temperatures defines an area of setpoints of acceptable humidities and temperatures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     Other objects and advantages will become apparent upon reading the following detailed description and upon reference to the drawings, in which  
         [0007]      FIG. 1  is a front elevation view of a xerographic or electrophotographic printer apparatus or machine that includes the inventive features of the invention;  
         [0008]      FIG. 2  is a side elevation view of the printer apparatus of  FIG. 1 ;  
         [0009]      FIG. 3  is a graph illustrating a temperature and relative humidity area of set points for control of temperature and relative humidity in the machine of  FIG. 1  in accordance with the invention; and  
         [0010]      FIG. 4  is a control diagram illustrating the control elements associated with the printer apparatus of  FIG. 1  and in accordance with the invention;  
         [0011]      FIG. 5  is a flowchart illustrating operation of a programmed control for controlling operation of a heater and a mist producing device to control temperature and relative humidity within the printer apparatus of  FIG. 1  in accordance with the invention. 
     
    
       [0012]     While the present invention will be described in connection with regard to preferred embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     With reference now to  FIGS. 1 and 2 , there is illustrated an exemplary printer apparatus or machine in this regard shown as an electrophotographic or xerographic reproducing apparatus  10  having an electrophotoconductive engine or module  15 . As is well known with regard to such apparatus, an EP processor includes an electrophotoconductive recording member  16  that is uniformly electrostatically charged by a primary charger  14 . The uniform electrostatic charge is then imagewise modulated or selectively removed using an exposure device such as an LED or laser imaging device  11  or by optical exposure of the electrophotoconductive member to a document. The recording member with the remaining electrostatic charge is selectively developed by an electroscopic toner from one or more development stations  17  that selectively develops the recording member in accordance with the charge remaining on the recording member. The developed toner image is then transferred to a recording sheet moving along a paper path  27 . The recording sheet may be either paper or plastic and may be supplied in the form of a roll of continuous recording sheets or discrete sheets stored in one or more trays  22 . The recording sheet with the developed image thereon is then passed through a fusing device  28  to fuse the image to the recording sheet. The recording sheet with the fused image thereon may be advanced so as to exit from the machine or collected in a tray or moved along the path  27 A in which the sheet is turned over for recording a second image on the opposite side of the recording sheet. The recording member  16  may be in the form of a belt or drum and the toner image on the recording member may be either directly transferred to the recording sheet or one or more images, such as plural color toner images, may be collected on an intermediate transfer drum  19  and then transferred to the recording sheet as a composite multicolor image. Alternatively, the recording sheet may have transferred thereto different color images to record a multicolor image. A cleaning device  26  may clean remnants of untransferred toner remaining on the recording member to prepare the recording member for recording each image.  
         [0014]     Also shown in  FIGS. 1 and 2  is an airflow inlet  12  into which cooling air is circulated into the apparatus and introduced from the bottom of the apparatus  10 . The airflow then exits at the top of the machine shown in  18 . With reference now to  FIG. 2 a  side elevation view of the apparatus  10  is shown and particularly illustrates in schematic form various components associated with the management of temperature and relative humidity within the apparatus  10 . As best seen in  FIG. 2  inlet air  12  enters a chamber and then is caused to be filtered by a particulate filter  30  for removal of dust particles and then by an amine filter  35  which removes amine compounds in the air. The air then passes over a heating coil  75  which heats the air in accordance with an algorithm to be described below. The airstream is then subjected to passage through a humidifier  55  which includes water for increasing humidity to the airstream entering the EP engine. As may be seen in  FIG. 2  the airstream is now positioned at the rear of the machine and is now caused to flow upwardly so as to flow over and provide cooling air to cool one or more electrical control board (s)  21  which provide electrical control of the EP process and the other components of the apparatus. The electrical control board(s)  21  is/are supported, so as to be vertically upstanding, by the back cover  23  of the apparatus  10 . The board(s)  21  may comprise a spaced series of boards that are spaced to allow air flow between them. (one of the boards is cut away to show the flow of air between them). The airstream is then moved transversely of the EP process path; i.e crosswise of the main path of movement or rotation of the belt or drum, to cool or temperature modulate components of the EP process, such as the photoconductive drum or belt  16  and the associated exposure and/or charging stations associated therewith, the intermediate transfer roller  19  and the development station  17 . The airstream also collects dust particles and ozone released as a result of the image forming process. The airstream then flows into a duct  37  formed integral with the front cover  24 . The front cover is pivotably supported to the housing of the apparatus  10  so as to be openable by the machine operator or a technician for service. Preferably, the air duct  37 , being integral with the front cover moves therewith when the front cover is opened. When the front cover door is in the closed position as shown the duct provides a passageway from the median portion of the machine to the top portion of the machine shown by the arrows. In the top portion of the machine the airstream is again subject to a filtration by a coarse filter  36 , a fine filter  32  and an ozone filter  32   a  before entering the blower  45 . This latter filtration protects the blower from contamination by toner collected through movement of the airstream through the machine and also reduces the particulate matter exiting the machine via the airstream. The airstream when exiting the blower  45  is then caused to pass over temperature and relative humidity sensors  38  and then exits the machine or apparatus as exhausted air at  18 .  
         [0015]     The airstream path described above has several advantages. Firstly, when the front cover or door  24  is opened to provide access to a serviceperson for service to the EP processor components the airstream path will be from where the air enters at the front door and then upwardly. Thus the airflow will not be in the case of a front cover or door opened condition as shown in  FIG. 2  with the solid arrow but will instead be in accordance with the dotted arrow  62 . Thus, the flow of air at the opened front cover will be substantial movement of outside air into the apparatus and away from the serviceperson, which may include the operator, and will not provide contaminated air that is coming from the EP process stations into the face of the operator. The above is also true if the back cover  23  is opened. A second advantage is that the airstream path being transverse to the EP process causes less disruption to that process in terms of dislodging or otherwise adversely affecting the image creation process.  
         [0016]     With reference now to  FIG. 3  there is shown a graph of temperature vs. relative humidity which comprises the potential operating space for these parameters in operation of the apparatus. An area identified as “target space” identifies an area of acceptable combinations of temperature and relative humidity for operation of the apparatus. In  FIG. 3  there are shown selected operating points A,B and C that are outside of the optimal target space. These may represent possible operating points that require adjustment in order for the machine to be operating within the optimal target space. As may be seen with regard to point A the minimum change needed to move into the target space is to increase relative humidity from 20 percent to about 50 percent without the need to change temperature. This may be accomplished by turning on the mist humidifier  55 . In the example where the current operating temperature and humidity is at point B and minimum change needed to be operating within the target space is to increase relative humidity from about 20 percent to 50 percent and to increase temperature from 60 degrees Fahrenheit to 70 degrees Fahrenheit. In the example of the current operating condition of point C, the minimum change needed to be operating within the target space is to increase temperature from 60 degrees Fahrenheit to 70 degrees Fahrenheit without increasing the relative humidity. It will be understood that since the humidity of the air within the machine changes with temperature that even though no change in relative humidity is required that some use of the mist humidifier will be required in order to maintain the relative humidity at the elevated temperature. It will further be appreciated that by not providing a single separate set point for each of temperature and relative humidity that great savings in controls necessary to maintain the environmental conditions within the machine are realized because of the tie-in between temperature and humidity.  
         [0017]     With reference now to  FIG. 4  there is shown a control diagram of movement of the airstream through various stations. The inlet air  12  enters the machine through the bottom of the machine as noted previously and is subject to filtration by particulate filter  30  and amine filter  35 . The airstream then passes over a heating coil  75  where it may be heated assuming that the heating coil is enabled by a heating control unit  120 . The heating control unit  120  may in turn control a rheostat or other variable regulator of electrical energy which may include solid-state devices. Power to the heating coil is provided by a power input module  170  which provides the input electrical power for all the electrical requirements for the machine including the EP module. The airstream then passes over the mist humidifier  55  which is supplied with water from the waterline  140  having a water filter. A valve or other mist regulator  150  may be provided to control the mist humidifier  55 . The mist regulator  150  may also include an electrically operated mechanical device which rotates to create mist. The mist regulator in turn is controlled by an RH controller  130  which may receive periodic control signals from the microprocessor  95  to operate the mist humidifier. Subsequently to being heated and subjected to the addition of moisture in the airstream, the airstream passes through the EP module  15  to provide the correct conditions of temperature and moisture to the components of the EP module. After passing through the EP module the airstream is subjected to filtration (filters  36 ,  32 ) again to remove contaminants swept up during passage through the EP module. The airstream is then subjected to being sensed by temperature and relative humidity sensors  38  before being exited from the machine at exit  18 . This may be seen in the diagram of  FIG. 4  and only one blower fan  45  may be needed to pull air into the machine and exit same from the top at exit  18 . When the front cover door is opened for maintenance of the EP processor components by the serviceperson, the blower  45  may be on to cause air to flow as illustrated by dotted line  62  in  FIG. 2 .  
         [0018]     With reference now to the flowchart  200  of  FIG. 5  in step  210 , temperature (T) and humidity, preferably relative humidity (RH) are sensed by sensors  38  and signals representing same are communicated to the microprocessor  95 . In step  220  the microprocessor determines whether or not the temperature and relative humidity are within the target space. As noted above the target space is generally a predetermined area in the temperature, relative humidity coordinate space and may be represented and stored in memory by values defining the boundaries thereof. For example in the illustration of  FIG. 3  the target space is represented by an area wherein the relative humidity is from about 50 percent to 70 percent and the temperature is in the range of 70 degrees Fahrenheit to 84 degrees Fahrenheit. Of course, other areas and not necessarily rectangular ones, may be used, to define the target space. If both temperature and relative humidity are within the ranges defined by the target space, no additional heating or additions of moisture to the airstream are needed. However, if the determination in step  220  is that a change is needed to temperature and/or relative humidity to place both the temperature and relative humidity in the target area or space then, depending upon the current condition of temperature and relative humidity and the minimum change needed to reach target space, temperature and/or relative humidity may be changed or adjusted in accordance with the determination, step  240 . The changes or adjustments are implemented by the microprocessor  95  controlling the heating control unit  120  and the relative humidity control unit  130  which in turn control the various mechanical and/or electrical devices  150 ,  160  associated with heating coil  75  and mist humidifier  55 .  
         [0019]     Although the invention has been described with reference to an electrophotographic engine for printing, other printers may make use of the invention. For example, photographic printers, electrostatographic printers, ink-jet printers, thermal printers and other printers requiring control of temperature and relative humidity. The term “process direction” is generally well-known and implies a direction of a paper path or movement of an imaging member such as a photoconductive belt or drum. In addition although description has provided with regard to sensing temperature of the airstream, it will be understood that temperatures of various components of the EP process may be measured and determination made based on a temperature of a certain component or a certain combination of components.  
         [0020]     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.  
       Parts List  
       [0000]    
       
           10  reproducing apparatus  
           11  imaging device  
           12  airflow inlet  
           14  primary charger  15  EP engine  
           16  Electrophotoconductive recording member  
           17  toner development stations  
           18  airflow exit  
           19  intermediate transfer drum  
           21  electrical control board(s)  
           22  receiver member (paper) supplies  
           23  back cover  
           24  front cover  
           26  cleaning device  
           27 A return path for receiver member  
           28  fusing station  
           30  particulate filter  
           32  fine filter  
           32   a  ozone filter  
           35  amine filter  
           36  coarse filter  
           37  air duct  
           38  temperature and relative humidity sensors  
           45  blower  
           55  mist humidifier  
           62  alternate are path flow (front cover door open)  
           75  heating coil  
           95  microprocessor controller  
           120  heating control  
           130  relative humidity controll  
           140  water line with water filter  
           150  water valve  
           170  EP module power input