Air Flow Through An Interior Space Of A Printer BACKGROUND

In various types of printer, a print applicator is used to transfer a print material such as ink, in the case of inkjet printers, or toner, in the case of laser printers, onto a print medium, such as paper. For example, in the case of an inkjet printer, a print applicator in the form of a print head comprising an array of nozzles may be used to transfer ink onto paper.

BRIEF DESCRIPTION

Reference will now be made by way of example only to the accompanying drawings in which:

Fig. 1 illustrates an example apparatus 101 ;

Fig. 2 illustrates the apparatus 101 including a print applicator 201 according to an example;

Fig. 3 illustrates a side interior view of an apparatus 301 according to an example;

Fig. 4 illustrates a perspective view of an assembly 501 comprising a fan 106 and manifold 31 1 according to an example;

Fig. 5 illustrates a bottom view of the assembly 501 shown in Fig. 4 according to an example;

Fig. 6 illustrates a front interior view of the apparatus 301 shown in Fig. 3 according to an example;

Fig. 7 illustrates a side interior view of an apparatus 701 according to an example;

Fig. 8 illustrates a front interior view of the apparatus 701 shown in Fig. 7 according to an example; and

Fig. 9 illustrates a method of printing according to an example. DETAILED DESCRIPTION

The Figures illustrate an apparatus 101 comprising: a housing 102 defining an interior space 103 of a printer, the interior space 103 to contain a print applicator 201 at a location 104; and a fan 106 to cause a flow of air from the fan 106 through the interior space 103 of the printer towards the location 104 when a print applicator 201 is located at the location 104. In an example, the fan 106 may be configured to cause a flow of air from the fan 106 through the interior space 103 of the printer towards the location 104 when a print applicator 201 is located at the location 104 and also when a print applicator 201 is not located at the location 104. In an alternative example, the fan 106 may be configured to cause a flow of air from the fan 106 through the interior space 103 of the printer towards the location only when a print applicator 201 is located at the location 104.

The apparatus may comprise a component 105 of the printer that would otherwise be susceptible to contamination by aerosol from a print applicator during printing, but the fan 106 is configured to cause a flow of air from the fan past the component 105 towards the location 104 of the print applicator 201 . Therefore the flow of air helps to resist movement of aerosol towards the component. In the examples of Figures 1 and 2 the component 105 is electronic circuitry 105 to control a print applicator 201 (not shown in Figure 1 ) at the location 104, but in other examples the component may be a user operable latch, or an encoder strip, or another component that is sensitive to contamination.

The apparatus 101 may comprise a printer, such as an inkjet printer or a laser printer, or the apparatus may be a module from which a printer may be formed. As used here 'module' refers to a unit or apparatus that excludes certain parts/components that would be added by an end manufacturer or a user.

In the examples shown in the Figures the apparatus 101 is itself a printer. The word 'printer' is used here to mean an apparatus that is usable to print a print material such as ink or similar fluid or toner onto a flexible print medium such as paper. Thus, a 'printer' may also have additional functionality such as the ability to scan an image, in order to produce a reprographic copy of an image. The apparatus may also include a mechanism 107 for moving print medium past the location 104 of the print applicator 201 .

In an example, the apparatus 101 comprises an inkjet printer, and the print applicator 201 is a print head comprising an array of nozzles. The print head may be supported on a carriage that is arranged to move back and forth along a rail across the width of the print media as the media moves past the rail and the print head prints onto the media.

In another example, the apparatus 101 comprises a page-wide array (PWA) inkjet printer, and the print applicator 201 is a page-wide array print head comprising an array of nozzles. The array contains many nozzles (possibly several hundred thousand) that are arranged to extend across the full width of an area that it is intended to print on. In this case, the print head is static during printing, i.e. it does not scan across the print media.

In each case, when the printer is performing print operations the print head generates aerosol that could contaminate surfaces within the printer.

The electronic circuitry 105 of Figure 1 and Figure 2, in the form of a printed circuit assembly (PCA), is used to provide power to the print head and also provide data to instruct each of its nozzles when to eject ink and how much ink to eject. As shown in Fig. 2, the electronic circuitry 105 may itself comprise a processor 203 that is used to process instructions received from a main printed circuit assembly 202 to generate the instructions for the print head. In an example, the processor 203 may comprise a field programmable gate array (FPGA).

Higher print speeds and larger arrays of nozzles on the print head may require faster processing by the processor 203, and consequently large amounts of heat may be produced by the processor. In the case of a page- wide array print head, this problem is enhanced by the fact that the print head, and hence the processor, is static during operation. I.e. there is no forced-air cooling by movement of the processor. Consequently, in order to allow the electronic circuitry to lose its heat it is preferable for the circuitry 105 not to be encapsulated but to be exposed to the air within the printer. A potential problem with this is that the electronic circuitry could become contaminated by the above-mentioned aerosol, and this could create short-circuits in the circuitry.

However, the fan 106 is configured to cause a flow of air from the fan 106 past the electronic circuitry 105 towards the location 104 where the print head 201 is positioned. Thus, the fan is configured to cause a flow of air from the fan into the interior space to control movement of aerosol during printing, and aerosol generated by the print head is blown away from the electronic circuitry. The flow of air over the electronic circuitry 105 also assists cooling of the electronic circuitry.

The housing 102 may define an inlet and the fan 106 may be configured to provide a flow of air through the inlet 108 into the interior space 103 of the printer. The flow of air produced by the fan may cause a positive pressure in the interior space compared to outside the housing, that is, the fan may be configured to provide an air pressure within the interior space that is higher than the pressure outside of the housing 102. Therefore, in the case where the apparatus is a printer and the housing 102 is the outer casing of the printer, the fan 106 may be configured to produce an air pressure within the inner space 103 that is above ambient atmospheric pressure.

The housing 102 may be provided with an outlet specifically for the purpose of releasing air from within the housing. The fan is therefore configured to provide a flow of air through the air inlet, through the fan into the interior space and through the outlet. In addition to, or alternatively to, such an outlet, other gaps that are inherently present may also provide an outlet to allow air within the housing to escape. For example, an inlet and/or an outlet 109 for media, and/or gaps around doors, paper trays etc. may provide air outlets. In examples of the invention, the fan 106 is configured to provide sufficiently high air pressure within the housing such that air tends to be forced out through the inherent outlets, such as the media inlet/outlet, gaps around doors, gaps around paper trays, etc.

By creating this positive air pressure within the housing 102, which forces air out through the media inlet/outlet 109, door/paper tray gaps, etc., external contaminants such as dust, etc., that might otherwise enter through these gaps, are prevented from entering into the printer housing.

In the example of Figure 1 , the printer 101 is shown without the print applicator 201 fitted at the location 104. However, the printer comprises a supporting structure 1 10, to receive the print applicator 201 , which defines the location 104 for the print applicator when fitted. In an example, the printer 101 is a scanning inkjet printer and the supporting structure is a moveable carriage for receiving a print head.

The example shown in Figure 2, is similar to that of Figure 1 , in that the printer 101 has a fan 106 to blow air into the space 103 defined by the housing 102 of the printer. However, in Figure 2 the printer 101 is provided with a print applicator 201 , located at the location 104 within the supporting structure 1 10. Consequently, during printing, the flow of air from the fan causes a flow of air from the fan past the electronic circuitry towards the location of the print head and past the print head before escaping from the housing through an outlet. The example of Figure 2 also has additional components 204, 205 located within the housing 102 to ensure that the flow of air from the fan 106 passes close to the electronic circuitry 105 and flows past the location 104 of the print applicator 201 . Components 204, 205 may be positioned spaced from the electronic circuitry and print head location 104 so that a constriction in the air flow is provided as it passes the electronic circuitry and/or the print head.

In the examples of Figures 1 and 2, the fan 106 is located above the interior space 103 of the housing and the electronic circuitry 105 is located above the location 104 of the print applicator 201 , such that in use the flow of air from the fan passes the electronic circuitry and down opposing sides of the print head. However, in alternative examples, the fan may be positioned in other parts of the printer and ducting may be used to channel an air flow from the fan into the interior space at the position and direction required. The fan 106 may be located inside the housing 102 adjacent to the air inlet 108 as illustrated in Figs. 1 and 2. In the illustrated examples, the fan 106 is an axial fan, but other means for causing the required flows of air may be used. For example, the fan 106 may be replaced by a radial fan. Another example printer 301 is shown in the side view of Fig. 3 and front view of Fig. 4. The printer 301 is a page wide array (PWA) inkjet printer having a print applicator 201 in the form of a print head mounted within a support structure 1 10 in the form of a print bar. The support structure 1 10 also supports electronic circuitry 105 and a user releasable latch 302. By releasing the latch a user is able to obtain access to the print head. The latch 302 partially covers the electric circuitry 105, but to ensure air flow cooling for the electronic circuitry the latch has an open structure. The printer 301 has a fan 106 providing a flow of air towards the electronic circuitry 105 and down past the print head 201 . Because the latch is adjacent to the electronic circuitry, the flow of air from the fan also blows over the latch and therefore prevents aerosol from the print head reaching the latch.

The example of Figure 3 also has a filter 303 upstream of the fan 106. Thus, the fan is configured to draw air in through an air inlet 304, through the filter 303 and blow it into the interior space 103 of the printer. In an example the filter comprises polyurethane foam that is porous but having hole sizes small enough to trap larger dust particles, paper fibres and the like. In an example the polyurethane foam is sandwiched between grid-like layers of a more rigid material to keep it in position.

In an alternative example to that shown in Fig. 3, the filter 303 is provided downstream of the fan 106, but in either case, filtered air is caused to flow from the filter into the interior space 103 of the printer. In the example of Fig.3, the fan 106 and the filter 303 are mounted on a door

305 which forms a part of the housing 102 and which provides access to the interior space 103 of the printer.

Features within the printer 301 provide constrictions to the flow of air around the print bar 1 10. To one side of the print bar 1 10 there is a structural element

306 (known as a link bar) that extends across the width of the printer and which produces a constriction 307 between itself and the print bar 1 10.

A service station 308 is located on the opposite side of the print bar 1 10 to the structural element 306. The service station 308 is supported on a service station beam 308A. The service station is configured to maintain the operability of the print head 201 . When printing is not being performed, the print bar is elevated from the position shown in Fig. 3 to allow the service station 308 to access the print nozzles on its lower surface 309. The service station may comprise a service cap used to cap the nozzles of the print head when it is not being used to prevent the nozzles from drying out and/or to perform a nozzle cleaning process.

The print head 201 and the service station 308 are shown in Fig. 3 in their printing positions. In this printing configuration, a narrow channel 310 is formed between the print applicator 201 (i.e. the print head) and the service station beam 308A. The narrow channel 310 provides a constriction through which air from the fan is able to flow, and blow aerosol produced by the printing process away from the electronic circuitry 105 and the latch 302.

In the example of Fig. 3, the printer also comprises an encoder strip 314. In the example, the service station has a component that moves across the width of the printer during a cleaning process, and the encoder strip is used to determine the position of this component. The encoder strip is mounted near to the upper face of the print beam 1 10 and close to the channel 310. Consequently the flow of air from the fan 106 down through the channel 310 also prevents aerosol from the print head reaching the encoder strip.

The printer 301 of Fig. 3 also comprises a manifold 31 1 having an inlet 312 to receive air from the fan 106 and an outlet 313 to release air into the interior space 103. The manifold 31 1 is shaped to direct air onto the upper side of the print bar.

An assembly 501 comprising the fan 106 and the manifold 31 1 is shown in the perspective view of Fig. 4 and the bottom view of Fig. 5. The inlet 312 of the manifold has a length (indicated by arrow 601 in Fig.5) and a width (indicated by arrow 602), and the outlet 313 has a length (indicated by arrow 603) that is longer than the length of the inlet and a width (indicated by arrow 604) that is narrower than the width of the inlet. The fan 106 is an axial fan, and so the length and width of the inlet 312 are substantially equal to match the circular shape of the fan. In contrast, the outlet 313 has an elongate shape having a length (603) much longer than its width (604). Consequently, the fan and manifold assembly 501 is able to provide a relatively wide flow of air across substantially the full width of the print bar, as shown in Fig. 4.

The outlet 313 may be a continuous opening, but as illustrated in Figs. 4 and 5, it may be divided up by inner walls 605 extending from the inlet 312 to the outlet 313. The inner walls 605 may be provided to equalise the rate of flow of the air across the width (603) of the outlet of the manifold.

For larger printers than that of Figs. 3 and 6, the printer may contain several assemblies 501 of fans 106 and manifolds 31 1 . An example of such a printer 701 is shown in the interior side view of Fig. 7 and interior front view of Fig. 8. It may be noted that the side view of printer 701 appears identical to that of the side view of printer 301 , and the components of the printer 701 have been labelled in the same manner as those of printer 301 in Fig. 3. However, printer 701 differs from that of printer 301 in that it is substantially wider, to enable printing onto a wider print media, and, as shown in Fig. 8, the transport mechanism 107 and the print head 201 are also correspondingly longer. Consequently, to provide a flow of air across substantially the whole width of the print bar 1 10, the printer 701 has been provided with a plurality (in this case 4) assemblies 501 of fans 106 and manifolds 31 1 .

A method of printing that may use one of the above described printers is illustrated by the flow chart of Fig. 9. At block 901 a flow of air is provided from a fan into the interior space of the printer over the electronic circuitry and past the print applicator. The flow of air may be through an air inlet of the printer into an interior space of the printer to provide an air pressure within the interior space that is greater than the ambient air pressure. Consequently, air is caused to flow out of openings such as gaps around doors, media inlets, paper trays, etc. to prevent external contaminants entering through these openings. In examples where the print applicator is a print head of an inkjet printer, and the print head is capped when not in use, the flow of air may be started a period of time before the print head is uncapped. In this way, a flow of clean air past the print head may be established before the nozzles of the print head are exposed, and so the risk of the nozzles becoming contaminated is minimised.

A period of time after starting the flow of air in block 901 , printing onto a print medium is started at block 902. During printing, print material (such as ink) is transferred from the print applicator to the print medium to form an image on the print medium, and aerosol is formed as a consequence of the printing. During printing, portions of the flow of air passing through the interior space pass downwards past the print applicator to control movement of the aerosol within the internal space of the printer and so, for example, resist movement of the aerosol towards electronic circuitry. In some examples, portions of the flow of air are caused to flow past opposing sides of the print applicator.

Printing is ended at block 903 before the flow of air is stopped at block 904. In examples where the print applicator is a print head of an inkjet printer, the print head may be capped before the air flow is stopped at block 904.

Although examples of the present invention have been described in the preceding paragraphs, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon. l/we claim: