Patent Publication Number: US-10329108-B2

Title: System and method for detecting a media supply

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Priority is claimed to U.S. Provisional application Ser. No. 62/550,150, provisionally filed on Aug. 25, 2017, entitled “SYSTEM AND METHOD FOR DETECTING A MEDIA SUPPLY”, in the names of Andrei Beletsky and James R. Gilbertson, which is incorporated herein by reference in its entirety. 
     Priority is claimed to U.S. Provisional application Ser. No. 62/598,617, provisionally filed on Dec. 14, 2017, entitled “SYSTEM AND METHOD FOR DETECTING A MEDIA SUPPLY”, in the names of Andrei Beletsky and James R. Gilbertson, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The disclosure relates generally to the field of imagers/printers, and in particular to a system and method for maintaining and distributing sheets of media. More specifically, the disclosure relates to a system and method for detecting a low media supply in a printer. 
     BACKGROUND 
     Media, for example paper or light sensitive, photothermographic film media, is used in many applications ranging from a standard photocopying apparatus, to graphic arts and/or medical imaging/recording printing systems. For example, in the medical industry, printing and imaging systems can range from more conventional printers that record textual, numeric, and graphical information onto paper media to high-performance laser imaging systems employing photothermographic film, such as are commonly used to produce photographic images from digital image data generated by magnetic resonance (MR), computer tomography (CT) or other types of scanners. Imaging systems that provide images from scanning systems typically include a laser imager for exposing an image on the photothermographic film, a thermofilm processor for developing the film through the application of heat, and an image management subsystem for coordinating the operation of the laser imager and the thermofilm processor. The resulting image is available for diagnostic use by medical radiologists and for communication to referring physicians and their patients. 
     Exemplary printers that are particularly suitable for printing medical x-ray images and other images used for diagnosis are known, for example, Carestream DryView Laser Imager (models include 5950 and 6950). Generally speaking, a photosensitive film laser imager includes a film supply system, a film exposure assembly, a film processing station (or developer), a film dispensing area and a film transport system. Each of these components are associated within a relatively large imager housing. 
     Sheets of unexposed photosensitive film are normally stacked in a sealed, standardized film cartridge, for delivery to the imager. The standard film cartridge can be sealed by a foil cover. During use, the film cartridge is inserted into the film supply system of the imager. The film supply system normally includes mechanisms for unsealing the film cartridge and subsequently removing individual sheets of film. In this regard, the film supply system separates and delivers an individual sheet of photosensitive film from the film cartridge to the film transport system. The film transport system, in turn, delivers the individual sheet of film to the film exposure assembly. Within the film exposure assembly, photographic images are exposed on the film from image data (e.g., digital or analog) using a laser imager. The exposed sheet of film is then transported, via the film transport system, to the film processing station where the film is developed. After thermal processing, the film is cooled and transported to the film dispensing area where the final image is available to the user. 
     The film supply system can be referred to as a Pickup Assembly, having an integrated pickup mechanism and a feed roller mechanism. The pickup mechanism separates the top sheet of film from the rest of the film supply/pack and lifts the film sheet into an open set of rollers in the feed roller mechanism. The feed roller mechanism then closes its set of transport rollers and transports the film into a Vertical Transport Assembly. 
     In various parts of the world, print kiosks are becoming widely used as print-on-demand systems for printing of medical data and images. Print kiosks can be configured with a variety of printer types, including both conventional off-the-shelf paper printers, monochrome or full-color, and high-performance laser-based film imagers. 
     While systems based on this model can provide suitable levels of performance and usability, there remains some room for improvement. In order to provide uninterrupted printing operation without requiring continuous monitoring and attendance by staff personnel, it is desirable that the media supply level be adequately tracked, so that a low paper or low film media condition can be detected and reported for correction before printing is interrupted. 
     Various methods for media supply tracking have been applied to other printer types. With today&#39;s high-performance imaging systems that record images onto film at high resolution, sufficient data for precise media tracking is often provided by the imager itself, commensurate with the cost of the system and media and with the need to maintain adequate levels of printer consumables in order to support imaging in the print-on-demand environment. 
     With more conventional paper printer equipment, however, media level tracking and reporting can be minimal and, even where provided, can be poorly suited to the demands of the print-on-demand kiosk environment. It may be difficult or impossible to provide accurate print media level information for support personnel without some type of printer reconfiguration or adding components within the printer. It is recognized that reconfiguration or invasive rework affecting print handling could affect printer performance and reliability as well as jeopardize printer warranty. Standard solutions that simply maintain a media count, measure relative stack thickness such as using surface contact or a magnetic threshold, or that test for successive lead edges, for example, can prove inaccurate or difficult to setup or adjust. Moreover, conventional measurement techniques may use sensing devices or mechanisms that are poorly suited to media type and packaging arrangements. Thus, it can be appreciated that there is a need for low media monitoring methods that are appropriate for applications for providing on-demand medical images and information to patients and health care providers. 
     SUMMARY 
     An object of the present disclosure is to address the problem of detecting a low media supply in a printer. Advantageously, embodiments of the present disclosure describe methods and mechanisms that provide non-contact media level sensing that is adaptable to different printer types and can be used with a range of print media substrates. 
     These objects are given only by way of illustrative example, and such objects may be exemplary of one or more embodiments of the invention. Other desirable objectives and advantages inherently achieved may occur to or become apparent to those skilled in the art. The invention is defined by the appended claims. 
     According to one aspect of the disclosure, there is provided a system and method for detecting a low media supply in a printer. The system comprises: a frame having a support/shelf for seating the printer thereon; a first light source that is positioned on the shelf and that is energizable to direct a first beam of light into the printer; a first detector that is positioned on the shelf and that provides an analog signal in response to reflection of the first beam of light from within the printer; and a control logic processor that is in signal communication with the first detector and that compares the analog signal to a predetermined/stored value and reports a low media condition according to the comparison. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings. The elements of the drawings are not necessarily to scale relative to each other. 
         FIG. 1  is a schematic diagram that shows components of a laser imaging system using film exposure according to an embodiment of the present disclosure. 
         FIG. 2  is a perspective view showing a print kiosk according to an embodiment of the present disclosure. 
         FIG. 3  is a schematic diagram showing functional components and interfaces of a self-serve print kiosk. 
         FIG. 4  is a perspective view that shows, from a rear view, internal components of a print kiosk with the outer chassis removed. 
         FIG. 5  is a perspective view that shows, from a front view, internal components of a print kiosk with the outer chassis removed and including printing and sensor apparatus related to media supply detection. 
         FIGS. 6A and 6B  show different types of printer apparatus provided with media sensor components of the present disclosure. 
         FIG. 7  is a perspective view that shows sensor apparatus provided on a printer support/shelf. 
         FIG. 8  is a perspective view that shows an upper media supply drawer. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following is a detailed description of the embodiments of the invention, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures. 
     The following references are incorporated herein in their entirely by reference: U.S. Pat. No. 6,883,796 (Nelson) entitled FILM SUPPLY SYSTEM FOR USING WITH A PHOTOSENSITIVE FILM IMAGER; U.S. Pat. No. 6,139,005 (Nelson) entitled FILM SUPPLY SYSTEM FOR USE WITH A PHOTOSENSITIVE FILM IMAGER; and U.S. Pat. No. 6,260,842 (Nelson) entitled FILM SUPPLY FOR USE WITH A PHOTOSENTIVE FILM IMAGER. These references are directed to film supply systems for use with a photosensitive film imager. 
     Reference is made to the following references, each of which is incorporated herein in their entirety: U.S. Pat. No. 6,661,979 (Barlow) entitled: SYSTEM AND METHOD FOR DETECTING LOW PAPER IN A PRINTER USING CONTINUOUSLY VARIABLE MEASUREMENTS; U.S. Pat. No. 5,629,672 (Brown) entitled: LOW PAPER DETECTION SYSTEM; and U.S. Pat. No. 6,929,417 (Boudreau) entitled: METHODS AND APPARATUS FOR SENSING A PAPER LOW CONDITION FOR FAN-FOLDED TICKETS IN A TICKET PRINTER. 
     Applicant has developed a method and system to prevent an out-of-media condition at a printer by generating a “low media” or “low paper” alert in advance of media depletion. It is intended to help prevent a situation wherein a customer is unable to print a report or wherein a report is only partially printed and the customer is unaware of it. 
     As used herein, the term “energizable” relates to a device or set of components that perform an indicated function upon receiving power and, optionally, upon receiving an enabling signal. 
     In the context of the present disclosure, the phrase “in signal communication” indicates that two or more devices and/or components are capable of communicating with each other via signals that travel over some type of signal path. Signal communication may be wired or wireless. The signals may be communication, power, data, or energy signals. The signal paths may include physical, electrical, magnetic, electromagnetic, optical, wired, and/or wireless connections between the first device and/or component and second device and/or component. The signal paths may also include additional devices and/or components between the first device and/or component and second device and/or component. 
     The description that follows describes apparatus and methods for tracking media supply levels at a device. With respect to print media management functions described herein, references to “paper” or to “film” in subsequent description can be interpreted broadly to be equivalent, encompassing any suitable type of sheet-based print substrate used for printer devices including photosensitive media. References to “printer” and “imager” can be considered equivalent and can be understood to relate to a range of imager devices that provide images on a substrate sheet, forming image content using exposure to light energy or by applying some type of marking material, such as toner, ink, ribbon-based colorant, or other marking material, to the imaging substrate. 
       FIG. 1  shows a front view of a laser imaging system  130  incorporating a film supply system in accordance with the present invention. The laser imaging system  130  generally includes an imager housing  132 , a film supply system  134 , a film exposure assembly  136 , a film processing station  138 , a film exit area  140  and a film transport system  142 . It should be understood that each of the components of the laser imaging system  130  are shown generally in  FIG. 1 . 
     The film supply system  134 , the film exposure assembly  136 , the film processing station  138 , the film exit area  140  and the film transport system  142  are all disposed at various locations within the imager housing  132 . During use, a cartridge of photosensitive film  144  is placed within the film supply system  134 . Upon activation, the film supply system  134  retrieves a single sheet of photosensitive film (not shown). The sheet of photosensitive film is delivered by the film supply system  134  to the film transport system  142  for delivery to the film exposure assembly  136 . Within the film exposure assembly  136 , photographic images are exposed on the film from image data (e.g., digital or analog), using a laser imager. The thusly exposed film is then transported via the film transport system  142  to the film processing station  138  where the film is developed. After thermal processing, the film is cooled and transported via the film transport system  142  to the film exit area  140 . For ease of illustration, the film travel path is represented by dashed lines  146 . 
     The film supply system  134  includes a cartridge receiving apparatus  148  and a film pick-up mechanism  150 . 
     A laser imaging system  130  such as that shown in  FIG. 1  can be incorporated into a self-service kiosk  10 , as illustrated in  FIGS. 2-3 , and described in U.S. 2017/0092036 (Wiens) published on Mar. 30, 2017, entitled KIOSK WITH PRINTER AND ROTATABLE SUPPORT, incorporated herein in its entirety. In a number of kiosk embodiments, two types of printing systems can be provided, such as laser imaging system  130  for imaging onto transparent film along with a monochrome or color printer for printing onto paper or similar reflective media. Alternately, two different paper printing systems could be used, such as of different types and having different paper stock types and sizes. 
     Kiosk  10  can be a stand alone unit, or can include means to communicate with other devices. For example, kiosk  10  can include a CPU/computer or a communication device (wired or wireless technology) for access to a CPU/computer/server located remote from the kiosk to obtain/access medical data including records and images. Kiosk  10  can include a communication device (wired or wireless technology) to communicate with other devices to obtain/access medical data. These devices can include, for example, another kiosk, systems of various medical modality (for example, MRI, Computed Tomography, Cone Beam Computed Tomography, or the like), and/or a network server allowing access to other CPUs/computers/servers. 
     In Applicant&#39;s system/method, to help prevent a printer that is used within a kiosk or used in some other unattended application from running out of media (i.e., paper, photopaper, film, photographic paper, and the like), the system/method monitors the media supply level using non-contact, optical sensing and generates a “low paper” alert, preferably in advance of the supply area becoming empty. 
     Applicant&#39;s solution is particularly suited for application in kiosk  10 , including managing the media supply for a printer that runs in a relatively unattended mode, having service intervention only when prompted. Using a self-service kiosk  10  such as illustrated in  FIG. 2 , a patient can enter identifying information and obtain a hard copy report that includes one or more diagnostic images. This system/kiosk can include one or more printers, housed within a cover chassis  26 . For example, in a preferred arrangement, the kiosk includes two high volume production paper printers, each with two media drawers (i.e., supply areas). Printers provided in the kiosk can be of the same type or of different types, such as printers that generate x-ray images on film in different size formats and printers that record onto paper media and generate full color image output, textual or graphical reports, and other data. 
     Without some type of low media detection and alert, a printer within kiosk  10  may run out of film or paper and be unable to start printing upon patient request. Or, if the media supply is exhausted during a print job, a requested report or series of images may print only partially, with the patient or other requester unaware that the full print job has not completed. 
     Using conventional monitoring approaches with kiosk printing systems, service personnel are generally alerted to a “no media” condition without any prior notice that the media supply is at low levels. Service personnel response can be delayed, inconveniencing patients and other print requesters. 
     Applicant&#39;s system/method adds a monitoring capability for the system to alert service personnel about low media supply status, with pre-determined “low paper” thresholds, i.e. approximate number of sheets of film or paper print substrate remaining in a tray when a “low paper” condition is triggered. 
     Applicant&#39;s system/method creates an advance warning, enabling the system to alert service personnel by displaying a message on the monitor screen or by sending an alert signal by other means. 
     Applicant&#39;s system/method can be used in a commercial (OEM), modular style system that has multiple media sizes and devices, including systems that print on different types of media or on different print media sizes. The solutions provided by the Applicant can be used on any of a number of printer types, including printers from different manufacturers, for example. The system described herein can sense multiple media sizes, maintaining sensors at the same location without obstructing movement of the printer tray(s), or without having excessive distance from the media edge. 
     Applicant&#39;s system/method uses optical sensing of the media supply level that can be configured and calibrated for the printer type that is used in a particular kiosk application. The Applicant&#39;s method can be used with any of a number of types of printers, including printers that record images onto film or paper. Advantageously, the method is not affected by variability in media sizes and fully or partially eliminates interference with internal parts and mechanisms of the printer, allowing it to be readily utilized for paper print systems using commercial OEM devices from various manufacturers. 
     Applicant&#39;s system/method for media supply sensing uses a reflective infrared sensor which is an analog device that outputs a gradually changing signal, based on the intensity of the reflected light, enabling the system to accurately determine media stack height. The sensor is in signal communication with control logic circuitry that analyzes the sensor signal to determine media level, either against a threshold “low media” value, or against a range of values indicative of media level. Advantageously, this type of sensing can be readily adapted to work with existing printer types that employ a media feeding mechanism conventionally used for paper printers of various sizes. In some applications, the Applicant&#39;s method can allow replacement or reconfiguration of printer types within a kiosk print system, requiring only minor recalibration for different media or printer types. The infrared sensing device is accurate in determining the media count when a suitable calibration method, as described below, is used. 
     Applicant&#39;s optical sensing system/method can be used having a sensor and associated printed circuit board (PCB) and cables installed completely outside an OEM (Original Equipment Manufacturer) printer, not requiring any OEM printer design change. Alternately, the sensing components can be fitted within an existing printer with minimal intrusion, as an add-on device, not interfering with printer paper-handling mechanisms and components and requiring minimal installation work. Communication between the sensor and control logic circuitry can be wired or wireless, such as using a Bluetooth or other high-frequency communication protocol. 
     Applicant has developed a system and method to increase accuracy of media supply/count detection and to avoid full or partial interference with internal parts of a printer. The method used by the Applicant employs non-contact surface sensing, with calibration that enables optical detection of media level based on thresholds set at calibration. Depending on printer configuration, the Applicant&#39;s method can use optical sensing of position of a mechanical surface within the device or reflection of light from an edge of the paper/film/media in the printer media drawer to reflect or block light. The Applicant&#39;s solution can be utilized among different types of printers and allows changes to be made to printer type using the same media level sensing hardware and logic control circuitry. 
     According to an embodiment, the surface of the lifting arm in the media feeder mechanism, located beneath the media stack for support from below, is used for sensing media level. A reflective sensor is energized to direct infrared (IR) light from below the printer, through the opening in the bottom of the media drawer and onto the bottom surface of the lifting arm of the feeder. Use of optical sensing in this way eliminates mechanical interaction with, or need of modification of, drawer or feeder mechanisms, especially when needed to enable the same detection method for different media sizes. Feeder arm behavior is the same for all sizes of compatible media, with different movement increments where media thickness changes from one type of media to another. 
     Rather than using visual (gradual) or magnetic (threshold) sensing of the feeder mechanism arm position, which gives very approximate information of remaining media level (possibly variable between printer loads and dependent on factors such as media sheet weight and overall printer condition), the reflected light is sensed to generate a variable analog signal which can be transformed into positional information for lifting arm proximity to the sensor. When used together with the calibration method described below, the analog signal output can be converted into accurate information about media stack height and corresponding remaining media count. 
     Applicant&#39;s method and system can be used with any printer type, but is especially suitable for use in a stand-alone imager, such as in kiosk printing system  10 , as illustrated in  FIGS. 2-3 . As noted previously, such a kiosk systems can be configured to use various different types of commercial printers having different media types and sizes, depending on the particular requirements of a site. Embodiments of the present disclosure provide a method that adapts to different printer and media types and minimizes interference with printer components and mechanisms, allowing reconfiguration of a kiosk print system without requiring replacement of media supply sensing hardware. As shown in  FIG. 3 , kiosk  10  includes a computer and, optionally, one or more additional control logic processors for functions such as media level monitoring and reporting, and one or more printers, having a display that provides operator and service messages. The kiosk  10  is typically in signal communication with a network server that can provide additional computational resources and can allow access to various types of imaging apparatus of different modality, including radiographic, MRI, and ultrasound systems, for example. 
       FIGS. 4, 5, 6A, 6B, 7, and 8  show aspects of positioning and configuration for detecting low media levels for a printer used within a self-serve kiosk or similar hardware architecture. 
       FIG. 4  shows, from a rear view perspective, a typical component layout within a frame  38  for kiosk  10 , with cover chassis  26  ( FIG. 2 ) removed. Media processing is provided by two imagers, an upper printer  90  and a lower printer  190 . Printers  90  and  190  can be of different types, such as one for film, one for paper or other reflective media, or one printer for color images, the other for monochrome. Printers  90  and  190  can also be used for media of different sizes. Control logic for kiosk  10  functions is provided through one or more control logic processors on a control PCB  34  and a computer motherboard PCB  36 . One or more cables  12  provide signal communication between these logic PCBs and other components. 
       FIG. 5  is a front view, showing a partially exploded view arrangement of kiosk  10  for upper printer  90 . In the configuration shown, printer  90  has two modular sections: a printer assembly  92  and an auxiliary feeder assembly  27 . Each of printer assembly  92  and feeder assembly  27  has a media supply drawer with a lifting arm for providing media, as described in more detail subsequently. The same basic sensing components can be used for sensing the lifting arm in each media supply drawer, with a mounting arrangement suitable to the upper or lower position. 
     As shown in  FIG. 5 , each printer  90  and  190  is seated on a support/shelf  46  or other support and has a lower media supply drawer  21  and an upper media supply drawer  22 . There is a printer assembly  92  for each printer  90 ,  190 ; each printer assembly  92  includes a corresponding upper media supply drawer  22 . There is also an auxiliary feeder assembly  27  for each printer; each feeder assembly  27  includes a corresponding lower media supply drawer  21 , as shown in  FIGS. 6A and 6B .  FIGS. 6A and 6B  show feeder assemblies  27  for two different printer models, along with the corresponding components that are added for sensing the position of the lifting arm that is in the printer assembly  92  above. 
     Within kiosk  10 , the printer support, shelf  46  as shown in  FIGS. 4 and 5 , can be rotatable about an axis, serving as a turntable to allow improved serviceability and positioning. This support can be rotated about an axis by any amount, for example, between 1 degree and 360 degrees. In a preferred arrangement, the support is rotatable about an axis by between 270 and 360 degrees. The embodiment of  FIG. 5  shows shelf  46  on drawer slides, making shelf  46  expendable to facilitate printer access for setup, paper loading, and maintenance. 
     To monitor the media supply level, there is an IR sensing apparatus  50  associated with each type of media supply drawer  21 ,  22 . A cable  32 , as shown in  FIG. 5 , connects IR sensing apparatus  50  with control and computer motherboard PCBs  34 ,  36 . A display monitor  48  provides an operator interface for kiosk  10  operation and shows alert messages related to media supply. As was shown in  FIG. 3 , a wired or wireless network connection also provides signal communication with other systems and devices for alerting support personnel to low media supply conditions. 
     IR sensing apparatus  50 , provided for each media supply drawer  21 ,  22  as noted above, includes a light source, such as an infrared (IR) light source, that is energizable to direct a beam of light into the printer mechanism and a reflective infrared sensor  52 , installed on Sensor PCB (printed circuit board)  2   a  or  2   b  connected by means of cable  32  or the like to Control PCB  34  which is, in turn, connected by means of cable  12  to Computer Motherboard PCB  36 . 
     For lower media supply drawer  21 , as shown in  FIG. 7 , sensor PCB  2   a  is installed outside printer  90 ,  190  and underneath a printer support, such as along a printer shelf  46 , through a cutout portion that lies right below the lower media supply drawer  21 . Sensor  52  directs IR light into the printer mechanism and senses reflection of the IR beam from a media supply lifting arm that rises when media is fed upward into the printer mechanism. 
     For upper media supply drawer  22 , as shown for two different imager types in  FIGS. 6A and 6B , sensor PCB  2   b  with sensor  52  is installed on top of feeder assembly  27  into a recession  56  in a plate  60 , such as a sheet metal cover, bracket, or other holder that is to be positioned right below the bottom opening in the upper drawer  22 . Plate  60  can be secured using tape, adhesive, or one or more fasteners, for example. 
     The relative position of recession  56  and of the corresponding bottom opening  58  in upper drawer  22  is illustrated in  FIG. 8 . Sensor  52  ( FIG. 7 ) directs IR light into the printer mechanism and senses reflection of the IR beam from a media supply lifting arm  54  or other type of media feed mechanism that raises when media is fed incrementally upward into the printer mechanism. 
     Referring to  FIG. 8 , lifting arm  54  rests on the drawer floor when printer  90 ,  190  is in standby mode. When printer  90 ,  190  is ready to feed media for printing, arm  54  is raised by the feeder mechanism up to the point when it starts compressing the media stack towards the feed rollers and the arm&#39;s movement stops. The range of travel of the arm between being raised with full stack of media on it (minimal travel) and with no media (maximal travel) is used as a proximity range for the sensor  52 , affecting intensity of the reflected infrared light and corresponding output voltage of the sensor which is processed by the Control PCB  34  and Computer Motherboard PCB  36  as described in the work flow. 
     The work flow includes three functions: (i) Calibration; (ii) Media Stack Height Calculation (employed during printing); and (iii) Low Paper Alert. 
     Calibration: 
     Signal calibration is typically a one-time procedure, performed during kiosk  10  assembly or installation, or whenever the corresponding operating system application executes. The printer  90 ,  190  is set to a ready state. The upper media supply drawer  22  is empty. As a result, feeder lifting arm  54  in the drawer  22  is raised by a feeder mechanism to its maximal travel point. In response to detection of the reflected light beam from the associated light source, sensor  52  outputs the corresponding analog voltage level which is converted to digital value by the Control PCB  34  software. That value is sent to the Computer Motherboard PCB  36  and stored (i.e., such that the value is a predetermined value), representing a calibration baseline voltage, for further comparison with values generated when printer  90 ,  190  is in normal operation and the media supply drawer  22  contains a stack of media. A similar procedure is executed for lower media supply drawer  21 . 
     Media Stack Height Calculation: 
     During printing, the feeder lifting arm  54  remains raised to a height that depends on the number of sheets of media remaining in the corresponding drawer  21 ,  22 . On each print cycle, the sensor  52  output voltage is converted to a digital value by Control PCB  34  software and then compared with the baseline voltage by requesting its digital value from the Computer Motherboard PCB  36  and calculating a difference value using Control board software  34 . 
     Low Paper Alert: 
     The resulting difference value from media stack height calculation is then compared, by a control logic processor, with a desired/pre-determined “low paper” threshold value. When this value goes below the threshold, a Low Paper alert is generated by Control PCB  34  software and is communicated to the Computer Motherboard PCB  36 . This generates a Low Paper alert message and displays it on the monitor screen and/or notifies service personnel by other means, such as using a wireless signal. This calculation, if desired, can use and display information about type of media that is to be loaded in the drawer (paper, photopaper, film, media, or the like), correcting the pre-determined system threshold (approximate media count below which Low paper alert is generated) for the different thickness of different media types. 
     An embodiment of the present disclosure can use reflected light to report a low media condition, such as where fewer than 20 sheets, or fewer than some other number such as 12 sheets, remain in the printer. A low paper threshold can be determined by the user or site where the kiosk  10  is installed, to provide a threshold media amount that is practical at that location. Thus, for example, the kiosk  10  control logic processor can be instructed to compare the analog sensor value against a value when the number of sheets remaining is at a particular level. Since the analog value returned from sensor apparatus  50  can be continuously monitored, an approximate “sheet remaining” value can be reported to staff assigned to printer maintenance. The sheet remaining value can be accessible remotely, allowing the maintenance staff to query kiosk  10  periodically using a wireless signal device for obtaining approximate media count, as an aid to scheduling and job assignment, for example. 
     For reconfiguration, such as for installation of a different printer  90 ,  190  in kiosk  10 , sensor apparatus  50  for the upper media supply drawer  22  can be repositioned. According to an embodiment, the same plate  60  can be used; alternately, plate  60  can be designed for the specific mechanical arrangement of a particular printer. The sensor apparatus  50  for the lower media supply drawer  21  is already in place on shelf  46 . However, it may be necessary to shift the position of sensor apparatus  50 . Shelf  46  can be fabricated to allow easy repositioning of sensor apparatus  50  for representative printer models. The calibration process can be repeated in order to put the newly installed printer into service. 
     It should be noted that sensor apparatus  50  is described using IR light, typically with wavelengths of about 700 nm or longer. However, light of other ranges can also be used, such as visible light, for example. 
     A computer program product may include one or more storage medium, for example; magnetic storage media such as magnetic disk (such as a floppy disk) or magnetic tape; optical storage media such as optical disk, optical tape, or machine readable bar code; solid-state electronic storage devices such as random access memory (RAM), or read-only memory (ROM); or any other physical device or media employed to store a computer program having instructions for controlling one or more computers to practice the method according to the present invention. 
     In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. 
     In the following claims, the terms “first,” “second,” and “third,” and the like, are used merely as labels, and are not intended to impose numerical requirements on their objects. 
     The invention has been described in detail with particular reference to a presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.