Background

[0001] Printing systems, such as scanning printers, page wide printers, copiers, etc., may generate text or images on to print media (e.g., paper, plastic, etc.). Printing systems can utilize a print substance that can be deposited on to the print media to generate the text or images on the print media. Printing systems can utilize a printbar with a plurality of dies that can include a corresponding plurality of orifices to deposit a print substance on to the print media.

Brief Description of the Drawings

[0002] Figure 1 is an example system for printbar spacing calibrations according to examples of the present disclosure.

[0003] Figure 2 is an example system for printbar spacing calibrations according to examples the present disclosure.

[0004] Figure 3 is a flow diagram illustrating an example method according to the present disclosure.

[0005] Figure 4 is a flow chart illustrating an example calibration system according to the present disclosure.

Detailed Description

[0006] in some examples, a printing device can be utilized to generate an image on a print medium by depositing a print substance on to the print medium. For example, the printing device can include a page wide printing device, a scanning

SUBSTITUTE SHEET (RULE 26) printing device, or other printing device. As used herein, a print substance can include a substance that is capable of generating an image on a print medium. For example, the print substance can include, but is not limited to, a fluid such as ink, a solid powder mixture such as toner, among other substances that can be utilized to generate images. As used herein, a print medium can be a substrate that can receive the print substance to generate a permanent or semi-permanent image. For example, a print medium can include, but is not limited to, paper, polymer, adhesive paper, metal, among other medias that can receive the print substance.

[0007] In some examples, a prihting device can include a printbar or print head that includes a plurality of print dies or a plurality of orifices to deposit a print substance. As used herein, a printbar can include a mechanism that can deposit a print substance at particular locations on the print medium to generate the image to be printed on the print medium. As used herein, a print head can include a mechanism that is capable of depositing a print substance on to a print medium. In some examples, the printbar and print head can be used interchangeably to describe a mechanism that can deposit a print substance onto a print medium. The printbar can include a plurality of print dies that each inciude orifices to deposit the print substance on to the print medium. In some examples, the plurality of print dies can be spaced along the printbar such that the plurality of print dies are capable of depositing the print substance across the entire surface of the print medium.

[0008] The printbar and corresponding print dies can be positioned at a particular distance from the print medium during printing operations (e.g., when the depositing print substance, etc.). This distance is referred to herein as pen to paper spacing and can have an effect on the print quality of images generated on the print medium. In some examples, the printing device can include a PPS value that can be a manufacturer pen to paper spacing vajue (e,g. , pen to paper spacing value utilized by the manufacturer, etc.) that the printing device is manufactured with by the manufacturer. In some examples, the manufacturer setting of the pen to paper spacing value can be considered a nominal pen to paper spacing value.

[0009] Manufacturer settings may have large tolerances between the printbar and the platen that result in setting a larger distance that would cause optimal performance to prevent the printbar from contacting media or other components of the printing system. Additionally, different printers may have dlfferent performance characteristics based on variance in manufacturing of the systems. Caltbraiion and adjustment of pen to paper spacing in a manufacturing setting can use substantial resources, tooling, and have errors. These calibrations may also be affected by shipping, installation, and over time of use.

[0010] The present disclosure relates to printbar spacing calibrations generated based on datuming the printbar to the platen based on electrical contact between the printbar and platen. In some examples, the printbar is lowered toward the platen until a controller receives an electrical signal indicating that the printbar is within a threshold proximity of the platen. The signal may be based on electrical contact such as a switch, based on a sensed capacitance, or based on other electrical signals, the electrical contact discussed herein Is generally discussed as between a portion of the printbar and a portion of the platen or media path. For example, the portion of the printbar may be a pen shield, a specific contact point, or another component that moves in a fixed position with relation to the printbar. In some examples, the electrical contact point me be grounded with respect to other voltage potentials in the system. The platen or media path contact may be the platen itself, a media bias arm, rollers supporting the platen, or other elements associated with the location of the paper when in the paper path, the media path contact may be electrically connected to a known voltage level such that when in contact or proximity to the grounded portion of the printbar and electrical signal is generated indicating that the contact is made.

[0011] Based on the position of the printbar with respect to the platen that the contact is detected, the printing system can store that value. For example, a motor that moves the printbar may have an encoder that provides a value indicating the relative position of the printbar. The position of contact can then be used as a reference point to move the printbar a preset distance back from the platen to provide an accurate pen to paper spacing for printing operations.

[0012] Elements shown In the various figures herein may be capable of being added, exchanged, and/or eliminated so as to provide a number of additional examples of the present disclosure. In addition, the proportion and the relative scale of the elements provided in the figures are intended to illustrate the examples of the present disclosure and should not be taken in a limiting sense.

[0013] Figure 1 is a block diagram illustrating components of an example printing system 100 for printbar spacing calibrations consistent with the present disclosure. The example printing system 100 includes a print zone 101. In these examples, the print zone 101 can be a portion of the printing system 100 where a print substance is deposited on to a print media. The printing system 100 includes a printbar 110 that includes print dies (not shown), or the like, to apply printing substance to print media; The printbar 110 may include s pen shroud 11S that protects print dies and/or pens,

[0014] In some examples, the print zone 101 can include a platen 150 id: support print media through the print zone 101. Print media may be directed across the platen 150 by one or more media bias members 125. The spactng between the platen 150 and the pen shroud 115 may be representative of the pen to paper spacing that is experienced during printing operations. As described herein, pen to paper spacing can affect the print quality of images generated by the printing device

100.

[0015] The printing systerfi 100 includ es an adjustment mechanism 130 to alter a distance bihyeen the printbar 110 andthe platen 150 in orderto adjust pen to paper spacing. In some examples; the adjustment mechanism 130 ean alter the position of the printbar 110 in fixed incremenis (e.g., 0,1 millimeter increments, 0.2 millimeter increments, etc,). In other examples, the adjustment meehanism 130 can alter the pen to paper spacing in a continuous way such that the alteration can be a non-fixed increment (e.g., slides down a rail, lowered along a rail system, etc,), [0016] The adjustment mechanism 130 is communicatively coupied to a controller 140 to control the adjustment mechanism 130 to position the printbar 110,

In some examples, the controller 140 may controller other operations of the printing system 100 such as drive mechanisms, ejection of printing fluids, image analysis, conditioning, or the like. As described herein, the controller 140 can include a number of processing resources capable of executing instructions stored by a memory resource, The memory resource, as used herein, can inciude a number of memory components capable of storing non-transitory instructions that can be executed by the controller 140.

[0017] In some examples, the wtmiler 140 can determine a plurality of pen to paper spacing values to be utilized for different types of print media, types of print jobs, or the like. The printing system 100 may position print bar 110 to those pen to paper spacing values based on a reference position determined based on datuming of the printbar to the platen 150.

[0018] in order to determine a reference position of the printbar 110 with respect to the platen, the controller 140 may instruct the adjustment mechanism 140 to move toward the platen 150 until a contact is detected between the electrical contact 120 and the media bias member 125. The electrical contact 120 as shown in Figure 1 is located on the pen shroud 115, however it could be located on another portion of the printbar 110, may be a separate contact extending from 110, but with a known position with respect to the printbar 110, or may be located on another part of the print head 110. The electrical contact 120 is held at a known voltage, such as ground, in order to aid in determining contact with the media bias member 125, [0019] The media bias member 125 may be charged at a different voltage than the electrical contact 120, For exampie, the media bias member 125 may be charged to a general purpose input/output value, or another voltage level utilized by the printing system 110, in various examples, other components of the printing system than the media bias member 125 may be used as contact point for contact member 120. For example, the charged element may be the platen 150, roller that support the platen, a separate contact point, or the like, in some examples, the charge between the electrical contact 120 and a contact point associated with the platen 150 may be reversed in polarity compared to as described herein.

[0020] In order to calibrate pen to paper spacing, the controller 140 moves the printbar 110 toward the platen 150 while monitoring signals from sensor 150. The electrical signals from sensor 150 change as the electrical contact 120 reaches a threshold proximity from the charged media bias member 125. For example, the sensor 150 may be coupled to the media bias member 125 and detect a voltage or current change when the electrical contact 120 comes into contact with the media bias member 125. For instance, a resistor (not shown) may separate the media bias member 125 from the voltage source such that the voltage at the sensor 150 drops to ground upon contact between the electrical contact 120 and the media bias member 125.

[0021] in sdme exampies, the eiectricai contact 120 and media bias member 125 may generate a capacitance that is measured by sensor 150. Accortiingly, the sensor 150 may monitor a signal representative of the capadtance and determine that the electrical contact is v«thin a threshold: distance of the media bias member

125 based on the change In capacitance. Accordingly, the Sensor 150 may output an electrical signal satisfying a threshold monitored by the controller 140 before actual contact between the electrical contact and the media bias member 125.

[0022] In various examples, the sensor 150 may be connected in a different position than shown in Figure 1. For example, the sensor may be connected in series or parallel in a circuit coupled to the media bias member 125. Furthermore, the sensor 150 may monitor other electrical signals than those discussed above.

The signals provided by sensor 150 are provided to the controller 140 in order to datum the printbar 110 at a reference position indicative of a minimum spacing between the printbar 110 to the platen 150. The: controller 140 can then use an encoder value of the adjustment mechahism 140 at thai mference position to determine: positions of the adjuStment mechanism I40 for pen to paperspacing based oh print media used fbr a print job.

[0023] In some examples, jhere may be multiple media bias members 125 and one or mom of those may be charged. For example, one media bias member 125 may be charged to reduce resources used for datumlng the printbar 110 to the platen 150, in some examples, multiple media bias members 125 may be charged to provide information about multiple points of spacing between the platen 150 and printbar 125 in the case that there Is a difference between the spacing.

[0024] Figure 2 is a block diagram illustrating an example system printing system 200 for calibrating pen to paper spacing based on contact datuming between a printbar 210 and a platen 230. The controller 2-40 executes caiibraboh instructions 245 to eaiibrate the position behA®en i|ie pphtbar ato and the platen 230 to a reference position to pse for pen to paper spacing during printing operations. The printbar 210 may be the same or similar to the printbar 110 discussed with reference to Figure 1 and the platen 230 may fee the same or similar to the platen 150 as discussed with respect to Figure 1.

[0025] The controller 240 executes the calibration instructions 245 to move the printbar 210 toward the platen 150. For example, the controller 240 may cause an adjustment mechanism, such as a motor, to move the printbar 210 toward the platen 230. The adjustment mechanism may include an encoder indicating a relative position of the mechanism as it moves. As the printbar 210 approaches or contact the platen 230, the controller 240 monitors electrical signals received from a sensor. when an electrical contact 220 of the printbar 210 contacts or reaches a threshold distance from the platen contact 235, the controller 240 determines that a threshold eiectticafsigriaiis Satisfied and stop movement ofihe printbar 210. The encoder poeitidri of the ddfuetmerit machariiamM that point can be used as a reference positipri indicating a miriimtim distance: between the printbar 210 and the platen 150.

The controller 240 can then instruct the adjustment mechanism to move a determined distance from the reference position to a pen to spacing distance for printing operations. [0026] The electrical contact 220 may be located on a pen shroud of the printbar 210, or another component that moves in a fixed position with the printbar

210 as the adjustment mechanism is actuated. The platen contact 235 may be a media bias member as shown in Figure 1, or may be another component in a fixed position relative to the platen 210. In various examples, the electrical signals interpreted by controller 240 may be representative of conductance, capacitance, or other physical measurements indicating electrical conduction between the electrical contact 220 and the platen contact 235.

[0027] Figure 3 is a flow diagram illustrating an example method to calibrate prinbar spacing according to the present disclosure. For example, the method may be performed by the components of a printing system or calibration system as described with reference to Figures 1 and 2 above. In various examples, the processes described in reference to flow diagram 300 may be performed in different order or the method may include fewer or additional blocks than are shown in figure 3.

[0028] Beginning in block 320, a printing system monitors an electrical signal to determine whether the electrical signal indicates the printbar satisfies a threshold proximity to a platen. For example, the threshold may be set as an indication that an electrical contact of the printbar contacted a platen contact of the piaten. The electrical signal may indicate conductance between the contacts, for instance. In some examples, the threshold may be an indication that the electrical contact is within a threshold distance from the platen contact, For instance, the electrical signal may be based on a capacitance measurement between the contacts.

[0029] The electrical signal may be generated and change as the printbar is moved toward the platen by an adjustment mechanism. The printbar may be moved to determine the reference position in response to installation of a printbar, start-up of a printing system, an predetermined intervals, in response to certain events, or at other times.

[0030] In block 340, the printing system sets a reference position of the printbar in response to the electrical signal satisfying the threshold. For example, the reference position may be based on an encoder value of an adjustment mechanism as the threshold is satisfied. Alter the reference position of the printbar is set based on datuming of the printbar to the platen, the printing system can use the reference position and predetermined pen to paper spacing settings lo adjust the position of the printbar to a spacing enabling printing operations.

[0031] Figure 4 is a block diagram illustrating an example calibration system 400 of a printing system according to the present disclosure. Calibration system 400 may include at least one computing device that is capable of communicating with at least one remote system, in the example of Figure 4, calibration system 400 indudes a controller 410 and a memory 420. Although the following descriptions refer to a single processor and a single computer-readable medium, the descriptions may aiso apply to a system with multipie processors and computer-readable mediums, in such examples, the instructions may be distributed (e.g., stored) across multiple computer-readable mediums and: the instructions may be distributed; {e,g executed by) across multiple processors. Controller 410 may be a central proceeding unit (CPUs), a microprocessor, and/or other hardware devices suitabie for retrieval and execution of instructions stored in memory 420, in the example calibration system 400, controller 410 may receive, determine, and send movement instructions 422, monitoring instructions 424, and positioning instructions 426 to calibrate pen to paper spacing of a printbar for a printing system. As an alternative or in addition to reirteving aod executing hstructions, coniroijer 410 may include an electronic circuit comprising a number of electronic components for performing the functionality of an instruction in memory 420, With respect to the executable instruction representations (e.g., boxes) described and shown herein, it should be understood that part or all of the executable instructions and/or electronic circuits included within a parttcular box and/or may be included in a different box shown in the figures or in a different boxnot shown: Memory 420 may be any eiectronic, magnetic, optical, or other physical storage device stores executable instructions, Thus, memory 4-20 may be for example, Random Access Memory

(RAM), an EIectrically-Erasable Programmable Read-Only Memory (EEPROM), a storage drive, an optical disc, and the like. Memory may be disposed within printing system 100, as shown in Figure 1 or printing system 200 as shown in Figure 2. In this situation, the executable instructions may be "installed” on the system 500.

[0032] Movement instructions 422 stored on memory 420 may, when executed by controller 410, cause the controller 410 to cause a printbar 430 to move toward a platen of a printing system. The monitoring instructions 424 stored on memory 420 may, when executed by controller 410, cause the controller 410 to monitor an electrical signal received from a sensor circuit 440 to set a reference position of the printbar 430. For example, the reference position may be set based on the electrical signal satisfying a threshold indicating a proximity between the printbar and the platen. The position instructions 426, when executed by controller

410, may cause the controller 410 to position the printbar based on the reference position to a predetermined pen tp paper spacing position. Aecordingly, the printbar may be positioned in a proper spacing to improve print quality as well as reduce potential damage to components of the printing system, in addition to the operations discussed, memory 420 may include additional instructions that enable additional systems and operations as described herein. For example, those processes described with respect to Figure 1-3 may be performed based on instructions stored on memory 420.

[0033] It will be appreciated that examples described herein can be reaiized in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM , whether erasable of rewritabie or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are examples of machine-readable storage that are suitable for storing a program or programs that, when executed, implement examples described herein. In various examples other non-transitory computer- readable storage medium may be used to store instructions for implementation by processors as described herein. Accordingly, some examples provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine-readable storage storing such a program.

[0034] The features disciosed in this specification (including any accompanying claims, abstract and drawings), and/or the operations or processes of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes are mutually exclusive.

[0035] Each feature disclosed in this specification (including any accompanying claims, abstract, and drawings), may be replaced by alternative features serving the same, equiva lent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is an example of a generic series of equivalent or similar features