GB2449939A

GB2449939A - Method of manufacturing a printhead support

Info

Publication number: GB2449939A
Application number: GB0711117A
Authority: GB
Inventors: Jagdish Pankhania
Original assignee: FFEI Ltd
Current assignee: FFEI Ltd
Priority date: 2007-06-08
Filing date: 2007-06-08
Publication date: 2008-12-10
Also published as: GB0711117D0

Abstract

A method of manufacturing a printhead support 7, the method comprises: providing a support member 7 with printhead connecting apertures 2D,2E-3D,3E etc positioned approximately where corresponding printhead alignment members are to be located; positioning the support member 7 on a jig 1 having spigots 2A,2B-6A,6B accurately located to correspond with the position of the print head alignment members, the spigots 2A,2B-6A,6B being received in respective ones of the apertures 2D,2E-3D,3E; supplying a hardenable material into the gaps defined between each spigot 2A,2B-6A,6B and the surrounding aperture 2D,2E-3D,3E; causing the material to harden and adhere to the apertures 2D,2E-3D,3E; and, removing the support member 7 from the jig 1. The hardenable material may be Diamant Moglice and it may be hardened through heating and/or curing. There is also provided an inkjet printhead (20, Fig.4) having alignment members and means for securing the printhead (20, Fig.4) to the printhead support member 7.

Description

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METHOD OF MANUFACTURING A PRINT HEAD SUPPORT

The invention relates to a method of manufacturing a print head support.

Conventional print heads such as inkjet print heads are mounted on a support member such as a metal plate which is then secured in a printer. In order to be able to print ink accurately on a record medium, it is important that each print head position is accurately known and controlled. This becomes even more important when a number of print heads are provided on the same support member since their relative positions must be known accurately.

In order to achieve accurate positioning, it is conventional practice to accurately machine print head connecting apertures in the support plate. The problem with this approach is that it is expensive and time consuming to achieve accurate machining of such apertures for each plate being manufactured.

In accordance with the present invention a method of manufacturing a print head support comprises i) providing a support member with print head connecting apertures positioned approximately where corresponding print head alignment members are to be located; ii) positioning the support member on a jig having spigots accurately located to correspond with the position of the print head alignment members, the spigots being received in respective ones of the apertures; iii) supplying a hardenable material into the gaps defined between each spigot and the surrounding aperture; iv) causing the material to harden and adhere to the apertures, and, v) removing the support member from the jig.

With this invention, a single, accurately machined jig is used but it is not necessary accurately to machine each support member. Instead, the walls of the final apertures within the support member are defined by the hardened material which will automatically be accurately aligned. Since only the jig needs to be precision machined, the overall expense in producing support members is significantly reduced.

Typically, the support member comprises a plate, particularly a metal plate, made of a material with a low coefficient of thermal expansion For example 1 7- 2.Opm/m at 20-90 C. Suitable materials include INVAR, molybdenum and machinable ceramics. Typically, more than one set of connecting apertures will be provided on the support member with corresponding spigots on the jig so that more than one print head can be mounted to the support member.

Furthermore the support member will typically include a slot positioned relative to the connecting apertures to receive the body of a print head mounted to the support member. This ensures that the print head is firmly held on the support member.

Suitable hardenable materials include Diamant Moglice. These materials can be hardened by heating and/or curing.

An example of a method according to the invention will now be described with reference to the accompanying drawings, in which:-Figure 1 is a perspective view of a jig or replication fixture; Figure 2 is a perspective view of a support plate mounted on the jig of Figure 1 but following the supply of hardenable material; Figure 3 is a perspective view of the support member or plate following separation from the jig, Figures 4 and 5 are perspective views of a print head from different angles; and, Figures 6 and 7 are a perspective view and cross-section respectively of a print head being offered up to the support plate.

As can be seen in Figure 1, the jig or replication fixture 1 is provided with five pairs of spigots 2A,2B-6A,6B which are accurately located to correspond with the required locations of alignment members of corresponding print heads. Typically, the jig 1 is a one-piece precision machined item.

A print head support plate (or support member) 7, made of a low coefficient of thermal expansion material such as INVAR, is then mounted on the jig 1 as shown in Figure 2. The plate 7 has five elongate slots 2C-6C machined in it which will receive respective print heads in use. In addition, on either side of the slots 2C- 6C are machined printed head connecting apertures 2D,2E,3D,3E etc. The connecting apertures 2D,2E etc are roughly machined and have a larger diameter than the corresponding spigots 2A,2B etc so that the plate 7 is a loose fit on the jig

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In view of this loose fit, small spaces exist between each spgot 2A,2B etc. and the corresponding apertures 2D,2E. While the plate 7 is held securely in place on the jig 1 by a clamp (not shown), these spaces are filled with a suitable, hardenable matenap such as Diamant Moglice. With the plate 7 still held firmly on the jig 1, this material is then hardened by heating and/or curing as shown in Figure 3, the material being indicated at 8-12.

Once the material has hardened and adhered to the walls of the apertures 2D,2E-6D6E, the plate 7 is released from the jig 1 as shown in Figure 3. The spigots 2A-6A are coated with release agent to prevent the hardenable material adhering to them This then leaves the apertures 2D,2E-6D,6E with walls defined by the hardened material 8-12. Because the relative positions of the spigots 2A,2B-6A,6B on the jig 1 are very accurately defined, the relative positions between the centres of the apertures 2D,2E-6D,6E as defined by the hardened material 8-12 are also accurately defined It is thus not necessary to precision machine the apertures in each plate 7.

Following manufacture of the support member as just described, a print head is mounted into each of the slots 2C-6C. We will describe the mounting of a print head to the slot 5C with reference to Figures 4-7.

Figure 4 illustrates a typical print head 20 having a main body 22 from which nozzles 24 protrude. A pair of mounting arms 26 extend from opposite sides of the body 22. A ribbon wire 28 extends from the body 22 to connect the print head to controlling electronics (not shown).

Each mounting arm 26 has a frusto-conical centring or alignment member 30 secured to it.

In order to secure the print head 20 to the support plate 7, the print head is offered up to the slot 5C (Figures 6 and 7) and bolts 32 are inserted into respective bores 34 in the mounting arms 26 while the frusto-conical centring members 30 are inserted into the connecting apertures 5A,5B. It will be appreciated that these apertures 5A5B have been lined by the hardenable material as explained above.

A pair of cylindrical locating slugs 34,35 are inserted into the apertures 5B,5A respectively and engage with the frusto-conical members 30.

The bolts 32 extend through the slugs 34,35 and through respective springs 36 and washers 37 and engage respective nuts 38 which are screw-threaded onto the bolts.

These assemblies are screwed together so that the nuts 38 are tightened onto the bolts 32 causing the washers 37 to engage the upper surface of the support plate 7 and portions of the frusto-conical centring members 30 to engage the locating slugs 34,35. In this way, the print head 20 is firmly secured to the support plate 7.

It will be noted in Figure 5 that the locating slugs 34,35 have slightly different forms. Thus, the locating slug 35 has an elongate slot 40 extending diametrically across its lower end while the locating slug 34 does not have a slot. The purpose of this slot is to enable left-right centring of the print head while it is being secured.

Claims

I CLAIMS

1 A method of manufacturing a print head support, the method comprising: I) providing a support member with print head connecting apertures positioned approximately where corresponding print head ahgnment members are to be located; ii) positioning the support member on a jig having spigots accurately located to correspond with the position of the print head ahgnment members, the spigots being received in respective ones of the apertures; iii) supplying a hardenable material into the gaps defined between each spigot and the surrounding aperture, iv) causing the material to harden and adhere to the apertures; and, v) removing the support member from the jig.

2. A method according to claim 1, wherein the support member comprises a plate, preferably a metal plate.

3. A method according to claim 2, wherein the plate has a low thermal coefficient of expansion, for example I.7-2.Opm/m at 20-90 C.

4 A method according to any of the preceding claims, wherein the support member and jig comprise a plurality of sets of connecting apertures and spigots respectively to enable more than one print head to be mounted to the support member.

A method according to any of the preceding claims, wherein the support member includes a slot positioned relative to the or each set of apertures to receive the body of a print head mounted to the support.

6. A method according to any of the preceding claims, wherein the hardenable material comprises Diamant Moglice

7. A method according to any of the preceding claims, wherein step iv) comprises heating and/or curing the material.

8 An ink jet print head assembly comprising a support member having a pair of connecting apertures; a print head having a pair of alignment members, the connecting apertures being aligned with the alignment members, first and second location slugs positioned in respective connecting apertures and receiving respective alignment members, wherein one of the slugs is constructed so as to permit lateral movement of the associated alignment member therein; and means for securing the print head to the support member.

9 An assembly according to claim 8, wherein said one of the inserts has a laterally extending slot which engages with a conically shaped one of the alignment members.

An assembly according to claim 8 or claim 9, wherein the print head is secured to the support member via respective securement members which extend through the corresponding alignment members and location slugs.

11. An assembly according to any of claims 8 to 10, wherein the support member has been manufactured according to any of claims 1 to 7.