Patent Application
20210331461
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.
Various examples are described below referring to the following figures:
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, and the heating elements may be arranged to heat different portions of the belt. A controller for the media conditioner is to provide separate power levels to the heating elements based on measurements from temperature sensors that monitor the conveying component. While active, the controller is to maintain the belt at a temperature set-point.
A complication may arise if, for example, one of the temperature sensors is misaligned. The sensor might detect a temperature that is lower than the actual belt temperature. This erroneously low temperature reading would be received by the controller. In this scenario, the controller is likely to provide more—or even too much—power to a heating element in an effort to drive the reading of the sensor up to the temperature set-point. The belt or a portion of the belt may become overheated, hotter than is desired or useful for conditioning the printable media.
To reduce the potential for this undesired outcome, in addition to other functions, the controller of the media conditioner is provided with 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. 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. 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. Other comparisons may be useful. 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 problem exists, allowing the issue to be addressed. The method disclosed herein can evaluate the performance of multiple heaters without consideration of temperature readings. More examples of media conditioners for media printing systems and techniques of evaluating them are described below.
The example of
Referring now to
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
Still referring to
The central, active portion 145 of inner heating element 142 is sized and positioned to heat the belt's inner portion 123 along the belt's inner surface 121A, and the first temperature sensor 163 is positioned to measure temperature on the outer surface 121B of inner portion 123. The outer, active portion 156 of heating element 152 of lamp 150 is sized and positioned to heat the belt's outer portion 124 along the belt's inner surface 121A, and the second temperature sensor 164 is positioned to measure temperature on the outer surface 121B of outer portion 124. In some examples, inner portion 123 and the first heating element 142 extend along 60% of the belt's width 122, and outer portion 124 and second heating element 152 extend along 40% of the belt'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
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 175A and code 175B. Code 175A, when executed by controller 170, is 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 175A is 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 the temperature of belt 120 at a desired temperature set-point. 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.
Machine executable code 175B in storage 174, when executed by controller 170, is to cause controller 170 (e.g., its processor 172) to evaluate the performance of heating elements 142, 152. In this process, the controller is to determine a first parameter based on the first power level and to determine a second parameter based on the second power level. The first parameter is to be indicative of the performance of the first heating element 142, and the second parameter is to be indicative of the performance of the second heating element 152. The first and second parameters may be selected from among a group of parameters associated with power level including, but not limited to: the power level signal of the controller, the power level received by the heating element, the current received by the heating element, a voltage across a heating element, and the temperature of the heating element, as examples. In various examples, media conditioner 110 has more or fewer of these or related parameters available for analysis by controller 170. For ease of conversation, a discussion given below will address examples in which the parameters evaluated by controller 170 while executing code 1756 include real-time values of a power level for the heating elements. The power levels are based on the needs that controller 170 perceives based on data from sensors 163, 164 according to code 175A, as discussed above. The methodology that is described is applicable to other power level parameters, such as those mentioned in this paragraph.
After controller 170 determines first and second parameters based on the power levels of the heater elements, the controller is to produce a result indicator based on a result of a comparison between the first and second parameters. The result indicator is, as examples, a signal from controller 170 that is initiated or a signal from controller 170 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 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 (e.g., a PWM signal) 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.
As an example, a comparison of parameters may be based on the first and second power levels for the heating elements 142, 152 of media conditioner 110 and may be calculated as show here using the difference between real-time values of those power levels:
PL1−PL2<−ΔPLmax
Or
PL1−PL2>ΔPLmax 1
where: PL1 is the power level of first heating element 142 of first heating lamp 140;
PL2 is the power level of second heating element 152 of second heating lamp 150; and
ΔPLmax is a threshold value equivalent to a maximum desired or maximum allowable difference between the power levels of the first and second heating elements.
Keeping the arithmetic difference between PL1 and PL2 less than the threshold value ΔPLmax is a goal of code 175B in this example. If a result of Expression 1 is true then the magnitude of the difference between power levels PL1 and PL2 is too large as compared to the threshold value, which is a failing condition for the operation of media conditioner 110. If instead, a result of following expression is true, then a “passing condition” has been determined for of media conditioner 110. This condition indicates that the power levels provided to heating elements 142, 152 are acceptably balanced, and temperature sensors 163, 164 are likely to be properly reading belt temperatures. The passing condition may be expressed as:
−ΔPLmax<PL1−PL2<ΔPLmax 2
The real-time values of PL1 and PL2 may be evaluated as single values or as averages, such as running averages calculated over a moving time period, as examples.
In the present example, the power levels for the heaters have been described in units of percent and may vary incrementally or smoothly from zero to 100% of a maximum power. Thus, a difference between power levels, such as the threshold value, ΔPLmax, may be expressed as a percent. Further, the threshold value, ΔPLmax, may be a constant value as exemplified here:
ΔPLmax=35% 3
In other examples, the threshold value is a constant value selected from the range: 5% to 40%. In still other examples, the threshold value is a constant value less than 5% or greater than 40%. In some of these examples, the threshold value is less than 60%.
The threshold value, ΔPLmax, may be evaluated based on an anticipated difference in power levels for a normal operating condition for media conditioner 110, which is identified by the variable: ΔPLnormal, in the next two expressions:
ΔPLmax=ΔPLnormal+20% 4
Like the 35% in Expression 3, the 20% in Expression 4 is provided as an example, and may be selected to be another value.
ΔPLnormal=(PL1−PL2)normal 5
The first and second power level values of PL1,normai and PL2, normal may be single values or may be averages, such as averages evaluated during a selected time period or averages of a selected number of data points collected earlier, as examples.
Whether using Expression 4 or 5 or another evaluation, the threshold value, ΔPLmax, may be determined based 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 determined based on the feed rate of media. The difference in power levels for a normal operating condition, ΔPLnormal, may be based on a design condition, such as the heating rate of the heat lamps 140, 150 and their heating elements 142, 152. Lamps 140, 150 and their heating rates may be selected based on the size ratio selected for the inner and outer portions 123, 124 of the width of belt 120 (
Referring to
In some examples discussed thus far, methods for comparing the performance of heating elements for a media conditioner can be accomplished without regard to any temperature measurements. Expressions 1 to 5 and the method of
In other examples, methods for comparing the performance of a first and a second heating element may be implemented with the additional knowledge of the temperature distribution across the heated conveying component, for example, belt 120. In general, controller 170 is to maintain a uniform temperature distribution across the width of belt 120, such that the difference in readings of the first temperature sensor 163 and second temperature sensor 164 is less than a predetermined temperature difference threshold value, using machine executable code 175A. If sensors 163, 164 have a difference greater than the threshold value, this condition may indicate that a portion of the belt has cooled too much and controller 170 may apply additional power to the corresponding heating element 142, 152 to make the belt temperature uniform again. However, if one of the temperature sensors is partially misaligned, that sensor might detect a temperature that is lower than the actual belt temperature. As a result, controller 170 may overheat a region of the belt in an effort to balance the temperature readings of sensors 163, 164. To check for this potential issue or for another cause of belt over-heating, controller 170 may implement a method for comparing the performance of a first and a second heating element, as described above.
In addition, in some examples of operating the machine executable code 175A, controller 170 is to determine a temperature difference before implementing the heating element performance comparison. For example, code 175B may cause controller 170 to determine a temperature difference between an average temperature on the belt's first portion 123 and average temperature on the belt's second portion 124. The averages may be evaluated over a time period or across a spatial distribution on belt portion 123 and on belt portion 124. In some examples, individual sets of temperature values from sensors 163, 164 may be used to calculate the temperature difference without averaging. If the calculated temperature difference is less than the temperature difference threshold value, then, for this example, the controller is to implement the heating element performance comparison, is to produce the result indicator, and may respond to it as described above.
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.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/042131 | 7/13/2018 | WO | 00 |
