Patent Publication Number: US-2021162777-A1

Title: Comparisons of temperatures on conveying components of media conditioners

Description:
BACKGROUND 
     Printing images or text on printable media in a printer includes various media processing activities, including pick-up, delivery to a print engine, printing, and conditioning of sheets of printable media. Conditioning involves heating and pressing the sheets through or past a heated pressure roller (HPR) to remove liquid (for printers using liquid ink), to remove wrinkles or curvature, or to reform or flatten fibers in the sheets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various examples are described below referring to the following figures: 
         FIG. 1  shows a media printing system, which includes a media conditioner in accordance with various examples; 
         FIG. 2  shows a partially schematic view of the media conditioner of  FIG. 1 , which includes heat lamps, a heated belt, and a controller in accordance with various examples; 
         FIG. 3  shows a bottom view of the heat lamps and a heated belt of  FIG. 2  in accordance with various examples; 
         FIG. 4  shows a schematic view of the media conditioner of  FIG. 2  in accordance with various examples; 
         FIG. 5  shows a flow diagram of a method of operating the media conditioner of  FIG. 2  in accordance with various examples; and 
         FIG. 6  shows a flow diagram of a method of operating the media conditioner of  FIG. 2  in accordance with various examples. 
     
    
    
     DETAILED DESCRIPTION 
     In the figures, certain features and components disclosed herein may be shown exaggerated in scale or in somewhat schematic form, and some details of certain elements may not be shown in the interest of clarity and conciseness. In some of the figures, in order to improve clarity and conciseness, a component or an aspect of a component may be omitted. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” Also, the term “couple” or “couples” is intended to be broad enough to encompass both indirect and direct connections. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally refer to positions along or parallel to a central or longitudinal axis (e.g., a central axis of a body or a port). As used herein, including in the claims, the word “or” is used in an inclusive manner. For example, “A or B” means any of the following: “A” alone, “B” alone, or both “A” and “B.” 
     In various examples, a media printing system includes a media conditioner coupled to a printer apparatus, which may also be called a print engine. The print engine is capable of forming an image on a sheet of printable media by a technology such as inkjet, laser, or digital offset, as examples. The media conditioner is positioned to receive sequentially sheets of printed media from the printing device after images are formed on the sheets. The images may include text, figures, or photographic images and may be black, monochrome, or multi-color, as examples. In various examples, conditioning the media includes heating the media, removing an ink solvent, melting an ink, or improving the flatness of the media. In various examples, the media printing system may also be called a printer, an all-in-one printer, or a photocopier. The media conditioner includes a conveying component to conductively heat and move a sheet of printable media and a first heating element and a second heating element to heat the conveying component. The conveying component may be a roller or a belt, as examples. In an example, the first conveying component is a belt, and the media conditioner includes a first heating element to heat an inner portion of the width of the belt, a first temperature sensor positioned to measure the inner portion, a second heating element to heat the outer portion of the width of the belt, which includes the two sides of the belt, a second temperature sensor positioned to measure the outer portion, and a controller to provide separate power levels to the heating elements based on measurements from the temperature sensors While active, the controller is to maintain the belt at a temperature set-point. 
     During operation, the controller is to make a determination based on recently measured values of operating temperatures from the first and second sensors, in view of set-point values or other anticipated values. A large difference between the measured and the anticipated temperatures or temperature differences may indicate a hardware or firmware issue needs attention. The determination may occur during various stages of operation, such as a heat-up, a cool-down, or steady state. 
     In addition, the controller may include functionality to compare the power levels of the heaters, or another set of parameters associated with the power levels, to evaluate the performance of the media conditioner, which may be helpful, for example, while the first and second sensors provide results that are or that appear acceptable. For example, the controller may calculate a running average of the power level that is provided to the first heating element over a time period and to calculate a running average of the separate power level that is provided to the second heating element over the same time period. The controller is to calculate an arithmetic difference between these two power levels and to compare that difference against a predetermined threshold value for the power levels. The controller is to perform a task if the difference is greater than the threshold value. The task may include, as examples, refusing to accept printable media, shutting-down, or sending a notification. In some examples, arithmetic differences are calculated for each reading of the two power levels, and the multiple values of these power level differences are then averaged and evaluated against the threshold value. In a scenario in which both temperature sensors are fully functional, but a temperature sensor is misaligned, a comparison of readings from the temperature sensors might not reveal the misalignment. In some examples, evaluating the relative power levels of the heaters, as described, could indicate that a heating issue may merit attention. Examples of media conditioners for media printing systems and techniques of evaluating them are described below. 
     The example of  FIG. 1  shows a media printing system  100  that includes multiple media trays  102  to hold multiple sheets of printable media  104 , a print engine  106 , a media conditioner  110 , and a finisher  112 . A media path  114  extends from media trays  102  to print engine  106 , media conditioner  110 , and finisher  112 . In the separate media trays  102 , the sheets of printable media may vary by face size, thickness, paper type, color, etc. 
     Referring now to  FIG. 1  and  FIG. 2 , media conditioner  110  includes a first conveying component coupled to engage a second conveying component to receive, contact, heat, and convey a sheet of printable media  104 . In this example, the first conveying component is a heated belt  120 , and the second conveying component is a driven roller  130 , which may be driven to rotate by a motor. Roller  130  extends widthwise along a central axis  131 . Media conditioner  110  includes a platen  134  and a platen support structure  135  to support and guide the belt  120 , a first and a second heater, a first and a second temperature sensor  163 ,  164 , a chassis  166 , and a controller  170 . In this example, the heaters are radiant heaters, which include a first lamp  140  having a first heating element  142  and a second lamp  150  having a second heating element  152 . Lamps  140 ,  150  are located within belt  120  to heat the belt by thermal radiation from the inside. During operation, roller  130  is conductively heated by contact with belt  120 , and media, when present, is to be heated by contact with belt  120  and roller  130 . In some examples, heating elements  142 ,  152  may be disposed outside belt  120 . Lamps  140 ,  150  may be halogen-type lamps, but other types of lamps or other types of heating elements may be used in various other examples to heat belt  120  or roller  130 . 
     Belt  120  and roller  130  contact and press against each other along a nip region  136  to receive and convey the media. Nip region  136  extends along the shared width of belt  120  and roller  130 . During operation, rotational movement of the roller  130  drives the belt  120  to rotate, with or without media, in between the roller  130  and the belt  120 . First and second temperature sensors  163 ,  164  are non-contacting thermistors located outside and below belt  120 . Other examples may include another form of non-contact temperature sensor or may include a contact temperature sensor located in an appropriate position. 
     Some examples of a media conditioner  110  include temperature sensors to monitor the temperatures at locations along the width of the second conveying component, for example roller  130 . Some examples of a media conditioner may include a conveying component, such as a belt  120  or a roller  130 , that is conductively heated. 
     Referring now to the bottom view of  FIG. 3 , belt  120  is shown as if a portion were removed, creating a window  126  that exposes an interior region of the belt, making lamps  140 ,  150  visible. Belt  120  includes an inner surface  121 A, an outer surface  121 B, and a width  122 , which can be considered to include a first or inner portion  123  and a second or outer portion(s)  124 . Belt  120  wraps around an axis  125  that extends widthwise. Outer portion  124  includes the two sides of the belt that extend in opposite directions from inner portion  123 . Thus, these “inner” and “outer” portions  123 ,  124  are defined along width  122  and are distinguished by vertical, dashed lines in  FIG. 3 . A portion or the entirety of first heating element  142  of lamp  140  and a portion or the entirety of second heating element  152  of lamp  150  extend axially within the loop formed by belt  120 , extending parallel to width  122 . Belt  120  is thus to travel in its loop around heating elements  142 ,  152 . 
     Still referring to  FIG. 3 , the first lamp  140  and its first heating element  142  extend lengthwise along a longitudinal axis  143  within a tubular bulb  144 , and the second lamp  150  and its second heating element  152  extend lengthwise along a longitudinal axis  153  within a tubular bulb  154 . Axes  143 ,  153  extend parallel to axis  125  of belt  120  and axis  131  of roller  130 . (Roller axis  131  is visible in  FIG. 2 .) When energized, a central portion  145  of first heating element  142  is active and producing heat, while the outer portion(s)  146  (e.g., beyond each end of central portion  145 ) produces little or negligible heat. When energized, the axially central portion  155  of second heating element  152  produces little or negligible heat; while the outer portion(s)  156  (e.g., beyond each end of central portion  155 ), of second heating element  152  are active, and producing heat. Thus, first heating element  142  may also be called an inner heating element, and second heating element  152  may also be called an outer heating element for width  122  of belt  120 . 
     The central, active portion  145  of inner heating element  142  is sized and positioned to heat the belt&#39;s inner portion  123  along the belt&#39;s inner surface  121 A, and the first temperature sensor  163  is positioned to measure temperature on the outer surface  121 B of inner portion  123 . The outer, active portion  156  of heating element  152  of lamp  150  is sized and positioned to heat the belt&#39;s outer portion  124  along the belt&#39;s inner surface  121 A, and the second temperature sensor  164  is positioned to measure temperature on the outer surface  121 B of outer portion  124 . In some examples, inner portion  123  and the first heating element  142  extend along 60% of the belt&#39;s width  122 , and outer portion  124  and second heating element  152  extend along 40% of the belt&#39;s width. A size ratio of 60:40 thus may exist for the inner and outer portions  123 ,  124  and between the effective heating lengths of lamps  140 ,  150 . In some examples, the ratio is greater than 60:40, and in some examples the ratio is less than 60:40. In some examples, the ratio is greater than or equal to 50:50 and less than or equal to 90:10. Other ratios are possible. 
     As shown in  FIG. 4 , controller  170  includes a processor  172 , storage  174 , electrical couplings  180  for heat lamps  140 ,  150 , and electrical couplings  182  for sensors (of which temperature sensors  163 ,  164  are examples). In various examples, controller  170  may be assigned to govern the operation of media printing system  100  as a whole or may be assigned to govern media conditioner  110  alone, being coupled to communicate with another controller of media printing system  100 . In some examples, controller  170  shares components, such as storage  174 , with another controller of media printing system  100 . 
     Storage  174  is a computer-readable storage medium storing, for example, machine executable code to be executed by processor  172 . In various examples, machine executable code may also be called machine readable instructions or computer executable code. The machine executable code stored in storage  174  includes code  175 A, code  175 B, and code  175 C. When executed by controller  170 , code  175 A governs the normal heating operations of lamps  140 ,  150 , code  175 B governs a power level evaluation for lamps  140 ,  150 , and code  175 C governs a temperature level evaluation for sensors  163 ,  164 . Code  175 A, when executed by controller  170 , includes instructions to cause controller  170  (e.g., its processor  172 ) to provide a first power level to first lamp  140  and its heating element  142  and to provide a second power level to the second lamp  150  and its heating element  152 , and to cause the first and second heating elements  142 ,  152  to generate heat to heat the belt  120 . In addition, code  175 A includes instructions to cause controller  170  to monitor signals or data from sensors  163 ,  164  to modulate the power supplied to heating elements  142 ,  152  and maintain a uniform temperature or a selected temperature distribution across the width of belt  120 , based on a targeted temperature set-point or set-points. The first and second power levels are variable. During operation, controller  170  is to provide separate first and second power level signals and may vary the signals to vary the first and second power levels provided to heating elements  142 ,  152 , respectively. In an example, the power level signals are pulse-width-modulated (PWM) signals. Whether controller  170  uses a PWM signal, another analog power level signal, or a digital power level signal, the signals may vary incrementally or smoothly from zero to 100%. The value of 100% power refers to the maximum power that the heating element can accept or the maximum power that the system can provide, whichever is lower. Broadly, the term “power level” will refer to the electrical power available to a heating element or used by a heating element, or it will refer to the power level signal for controlling the electrical power to a heating element. Although electrical couplings  180  are simply shown as a direct connection between controller  170  and heating lamps  140 ,  150 , in various examples, electrical couplings  180  connect the controller  170  to a power supply that feeds heating lamps  140 ,  150 . 
     Referring again to  FIG. 4 , machine executable code  175 C in storage  174  includes instructions that, when executed by controller  170 , cause controller  170  (e.g., its processor  172 ) to evaluate the performance of temperature sensors  163 ,  164  and heating elements  142 ,  152 . As a consequence of the performance evaluation of temperature sensors  163 ,  164 , controller  170  is to produce a result indicator based on comparisons between the temperatures and temperature differences for belt  120 . The result indicator may be, as examples, a signal from controller  170  that is initiated or a signal from controller  170  that is stopped. The result indicator may communicate a command to a component in media conditioner  110  or to a component in media printing system  100 . The command may be to stop or pause functioning or to perform an action. For example, the media conditioner may stop receipt of printable media in response to the result indicator. In some examples, the result indicator includes a signal that causes print engine  106  ( FIG. 1 ) to stop processing sheets of printable media. The result indicator may provide indication to a user. In some examples, the result indicator causes the media conditioner (e.g., controller  170 ) to set to zero the power level of heating element  142  or of heating element  152 . In several of these examples, the controller  170  is to transmit the result indicator to a component that is external to the controller. 
     The following discussion will describe an example of a temperature sensor performance evaluation for belt  120  in media conditioner  110  as may be implemented by controller  170  executing code  175 C. Expression 1, shown here, presents a failing condition for temperature measurements from sensors  163 ,  164  during the operation of media conditioner  110 : 
       ( T   1   −T   2 )−Δ T   ref   &lt;−T   tolerance  
 
       Or 
       ( T   1   −T   2 )−Δ T   ref   &gt;T   tolerance  
 
     In Expression 1, T 1  is a temperature of the belt inner portion  123 , as may be measured by sensor  163  during operation. The parameter T 2  is a temperature of the belt outer portion  124 , as may be measured by sensor  164  during operation. 
     The value ΔT ref  is a reference value describing an anticipated difference in temperatures for belt inner portion  123  and outer portion  124 . This reference temperature difference will be discussed below. The value T tolerance  is a tolerance or threshold value. 
     If a result of Expression 1 is true, then the difference between temperatures T 1  and T 2  is too large, which is a failing condition for the operation of media conditioner  110 . Detecting whether or not media conditioner  110  has reached a failing condition is a goal of code  175 C. Controller  170  is to produce the result indicator as a result of the failing condition being determined from Expression 1. 
     If instead a result of the following expression, Expression 2, is true, then a “passing condition” has been determined for media conditioner  110 . A passing condition indicates that the temperatures for belt inner portion  123  and outer portion  124  are acceptably balanced or have an acceptable difference and indicates that power levels provided to heating elements  142 ,  152  are likely to be set properly. A passing condition may be expressed as: 
       − T   tolerance ≤( T   1   −T   2 )−Δ T   ref   ≤T   tolerance     2 
 
     A passing condition is achieved when a comparison between the temperature difference (T 1 −T 2 ) during operation and the reference temperature difference, ΔT ref , returns a value that is equal to or less than the threshold value, T tolerance . For Expressions 1 or 2 the comparison is a subtraction, but in some examples, the comparison may use a ratio between the temperature difference (T 1 −T 2 ) and the reference temperature difference. A passing condition may be determined by Expression 2 producing a true result or by Expression 1 producing a false result. For convenience, the temperature difference (T 1 −T 2 ) may be called a first temperature difference, the reference temperature difference (ΔT ref ) may be called a second temperature difference, and the subtraction of these values ((T 1 −T 2 )−ΔT ref ) may called a third temperature difference. 
     In various examples, as a result of a passing condition, controller  170  is to produce no result indicator equivalent to the result indicator for the true result of Expression 1, or controller  170  is to cancel a result indicator that was activated based on Expression 1. For example, in a first time period (e.g., time period Δt 0 ) the controller may use Expression 1 or 2 and make a determination that activates the result indicator. During a subsequent time period (e.g., time period Δt 1 ), the controller is to evaluate updated values of the first, second, and third temperature differences and is to make an updated determination. If the magnitude of the updated value of the third temperature difference is less than or equal to the magnitude of the threshold value, the controller is to make a determination that a passing condition exists. As a result, the controller may cease to produce the result indicator. 
     Considering the parameters of Expression 1 and Expression 2 in more detail, the temperatures T 1  or T 2  may be measured by temperature sensors  163 ,  164 , respectively. Temperatures T 1  or T 2  reflect the current operating condition of lamps  140 ,  150  and may be called present or real-time temperature values, and the expression (T 1 −T 2 ) may be called a real-time temperature difference. The real-time values T 1  and T 2  may be evaluated as single values (for example, single values at a given time t 0 ) or as averages of a plurality of temperature values, such as running averages calculated over a moving time period, as examples. As used herein, including the claims, an operating condition of media conditioner  110 , its belt  120 , or its roller  130  may refer to a condition when media is being processed or when the equipment is in a standby or waiting mode, with heating elements  142 ,  152  active but waiting to process a piece of media, as examples. Thus, in various examples, an operating condition may be a processing condition or a stand-by condition. 
     The threshold value, T tolerance , may be a constant value as shown in this example: 
         T   tolerance =10 C   3
 
     In other examples, the threshold value is a constant value selected from the range: 5 C to 15 C. In still other examples, the threshold value is a constant value less than 5 C or greater than 15 C. In some examples, the threshold value is within the range zero to 20 C. The threshold value, T tolerance , may be determined based on limits of accuracy or on thermodynamic or heat transfer parameters related to belt  120 , roller  130 , heating lamps  140 ,  150 , another component, or the media (e.g., thickness, material properties, etc.), as examples. The threshold value may be based on the feed rate of the media. Although units of degrees Celsius are shown, any unit for temperature may be used. In some examples, voltage, current, or resistance values from a temperature sensor are used without converting the data to a unit that is specifically associated with temperature. 
     The difference in temperatures for a reference operating condition, ΔT ref , may be evaluated as: 
       Δ T   ref =( T   1ref   −T   2ref )   4
 
     In Expression 4, the parameter T 1ref  is a temperature of the belt inner portion  123 , and the parameter T 2ref  is a temperature of the belt outer portion  124  for the reference condition. The first and second reference temperatures may be single values or may be averages of multiple data points collected during an earlier time period, for example. The reference temperature difference ΔT ref  of Expression 4 is based on a reference condition, which may be a design condition related to a specified heating rate of the heat lamps  140 ,  150 , may be an operational period when the media conditioner  110  is known or perceived to be operating properly, or may be a desired condition or setting based on operational attributes (e.g., media size, density, or thickness or image size or density), as examples. The reference condition may be steady state, a heat-up ramp, or a cool-down ramp. 
     The evaluation of Expression 1 can also be written as: 
       |( T   1   −T   2 )−Δ T   ref   |&gt;T   tolerance    5
 
     Expression 5 provides a true result when an absolute value taken after subtracting the reference temperature difference, ΔT ref , from the real-time temperature difference, (T 1 −T 2 ), is greater than the threshold value, T tolerance . A true result from Expression 5 indicates a failing condition for media conditioner  110 . 
     Referring to  FIG. 5 , an example process  199  of controller  170  evaluating the performance of temperature sensors  163 ,  164  is depicted. During operation, at block  200 , controller  170  is to start executing machine executable code  175 C. At block  201 , the current value of the first temperature is to be retrieved or measured, and at block  202 , the current value of the second temperature is to be retrieved or measured. At block  203 , controller  170  is to perform a comparison between the first and second temperatures to determine whether they are improperly balanced or proportioned, as may be accomplished by selecting and evaluating Expressions 1, 3, and 4, for example. If the result of block  203  or Expression 1 is false (“No” in  FIG. 5 ), then controller  170  determines that the measured temperatures read by sensors  163 ,  164  are acceptable, such as according to process  199 , which is a passing condition, and operation of media conditioner  110  and printing system  100  continues. At block  204 , controller  170  is to wait a predetermined length of time (e.g., x seconds or milliseconds), and then to begin the comparison again from block  201 . If the result of block  203  or Expression 1 is true (“Yes”), then the temperatures provided to the first and second heating elements  142 ,  152  are determined to be improperly balanced, and controller  170  is to produce a result indicator at block  205 . As a consequence, at block  206 , controller  170  may perform an appropriate action, such as reducing the first and second power levels to zero or any of the other actions previously mentioned, as examples. In some examples, block  203  utilizes Expression 2 and the logic for process  199  is adjusted accordingly. In some examples, controller  170  continues to run process  199  and is to cease to produce the result indicator when a subsequent evaluation of Expression 1 returns a false value or Expression 2 returns a true value. In those examples, the operation of media conditioner  110  and system  100  may return to normal, assuming no other fault has occurred in system  100 . 
     In some examples, controller  170  includes wired circuits that accomplish some aspects of the functionality described for codes  175 A,  175 B,  175 C. Controller  170  may be implemented within a single housing or may be distributed in multiple housings or circuits through the extent of media conditioner  110  or printing system  100 . 
       FIG. 6  presents an example of a method  300  for comparing the temperatures on portions of a conveying component in a media conditioner. A goal of method  300  is to confirm that a uniform temperature or a selected temperature distribution exists across the width of the conveying component. Block  302  of method  300  includes forming a first comparison between a first temperature measurement of a first width portion of a conveying component of a media conditioner and a second temperature measurement of a second portion of the conveying component. Block  304  includes forming a second comparison between a first reference temperature of the first portion of the conveying component and a second reference temperature of the second portion of the conveying component. Block  306  includes forming a third comparison between the first comparison and the second comparison. Block  308  includes producing a result indicator based on a result of the third comparison. 
     In an example, method  300  includes the use of Expression 1 (above). In this example, forming the first comparison of Block  302  includes determining a first temperature difference, e.g., (T 1 −T 2 ), the real-time temperature difference between the first and second measured temperatures. Forming the second comparison of Block  302  includes determining a second temperature difference, which may be the reference temperature difference, ΔT ref , evaluated from first and second reference temperatures, T 1ref  and T 2ref , as shown in Expression 4, above. Forming the third comparison of Block  306  includes determining a third temperature difference between the first temperature difference and the second temperature difference. For example, in Expression 1, the third temperature difference is (T 1 −T 2 )−ΔT ref . At Block  308 , the result indicator is to be generated or produced when the third temperature difference of Block  306  is greater than the threshold value, e.g., T tolerance , or less than the negative of the threshold value, which would be a “true” result from Expression 1, representing a failing condition for media conditioner  110 . This outcome may also be described by stating that the result indicator is to be produced if the magnitude of the third temperature difference is greater than the magnitude of the threshold value. Thus, in this example, method  300  evaluates a comparison that includes the first temperature difference, the second temperature difference, and a threshold value and is to produce a result indicator based on the comparison. The method may further include ceasing to produce or negating the result indicator in response to the magnitude of the third difference becoming equal to or dropping below the magnitude of the threshold value in a subsequent time period. 
     The third comparison of Block  306  may also be evaluated using Expression 5, which also involves a first, a second, and a third temperature difference. Then, At Block  308 , the result indicator may be generated or produced when the absolute value of a subtraction of the second temperature difference from the first temperature difference is greater than a threshold value. 
     In some examples, method  300  includes the use of Expression 2 to perform corresponding activities and to achieve the accomplishments described herein. Some implementations of method  300  may incorporate other functionalities disclosed herein. Various examples of method  300  may be implemented in media conditioner  110 , and some examples, the functionality of method  300  is included in code  175 C ( FIG. 4 ). 
     The above discussion is meant to be illustrative of the principles and various examples of the present disclosure. Numerous variations and modifications will become apparent to those skilled in the art. It is intended that the following claims be interpreted to embrace all such variations and modifications.