WO1994016897A1

WO1994016897A1 - Electrode assembly for an ink jet printer

Info

Publication number: WO1994016897A1
Application number: PCT/GB1994/000146
Authority: WO
Inventors: Colin Edward Chamberlain; Ammar Lecheheb; Danny Charles Palmer; Jerzy Zaba
Original assignee: Domino Printing Sciences Plc
Priority date: 1993-01-27
Filing date: 1994-01-26
Publication date: 1994-08-04
Also published as: GB9301600D0; JPH08507007A

Abstract

A method of manufacturing an electrode assembly for an ink jet printer comprises disposing, in a mould body having a passage defined therethrough, a plurality of disk electrodes (5, 14) and a cylindrical electrode (1) in longitudinal alignment at fixed positions. An adhesive (26) is then injected into the mould around the electrodes (1, 5, 14) allowing the adhesive (26) to set. The assembly of electrodes is then removed from the mould and inserted into a bore (28) in an electrode-supporting body (27). Further adhesive (26) is injected into the body (27) to fix the electrode assembly (1) therein.

Description

ELECTRODE ASSEMBLY FOR AN ^{τ r}. JET PRINTER

The present invention relates to an electrode assembly for a continuous ink jet printer. Such printers are well known and comprise a nozzle through which a jet of ink is ejected under pressure, modulated by .a transducer which is usually of the piezoelectric type. After leaving the nozzle the jet breaks up into droplets of uniform size and these are selectively charged by passage through or past a charge electrode and then deflected correspondingly by passage between a pair of charged plates on to a substrate in order to print characters or the like on to the substrate. Additional electrodes, known as the phase detector electrode and the velocity sensing electrode may be provided.

However, accurate location of the various components relative to one another is difficult to achieve and so it has been proposed to form the electrodes as a monolithic block and in an integral unit by electrodeposition of the various electrode components on a single substrate. These methods, although involve less costly manufacturing techniques, give a low signal to noise ration and present a problem as regards material compatibility with the inks generally used in ink jet printing which tend to attack many materials. Furthermore, connecting together the various components to form the whole is difficult to achieve accurately and there may be problems with unreliability. According to the present invention therefore, there is provided a method of manufacturing an electrode assembly for an ink jet printer, which comprises disposing, in a mould body having a passage defined therethrough, a plurality of disk electrodes and a cylindrical electrode in longitudinal alignment at fixed positions, injecting an adhesive into the mould around the electrodes, allowing the adhesive to set, removing the assembly of electrodes from the mould, inserting the assembly into a bore in an electrode-supporting body, and injecting adhesive into the body to fix the electrode assembly therein.

By this means, the precise relative location of the electrodes can be accurately determined in advance, but the manufacturing costs can be kept to acceptable levels.

Preferably, the mould body comprises a plurality of annular recesses around the passage and the electrodes are disposed in respective recesses to fix their position relative to one another.

Preferably, the electrodes are ring-shaped and the mould body is split to enable insertion of the electrodes and removal of the fixed assembly.

After fixing of the assembly in the electrode- supporting body, a longitudinal slot can be formed through the body and assembly in order to provide a passageway from the centre of the electrodes to the outside of the electrode body, so that it may be moved laterally into position once a stream of droplets has been established in the printhead.

To reduce cross-talk between the electrodes, intermediate earthed shields of similar shape may be provided in positions between the electrodes, being moulded in position in the same steps as defined above. The invention also includes an electrode assembly and electrode body manufactured by the method defined above.

One example of a method according to the present invention and an electrode body formed by the method will now be described with reference to the accompanying drawings, in which:-

Figure 1 is a side elevation of a charge electrode shown attached to its associated conductor;

Figure 2 is a similar view of a phase detector electrode and associated shield, again connected to the associated conductors;

Figure 3 is a similar view of a velocity detecting electrode and a pair of shield plates; Figure 4 is a partially sectioned view of the assembled electrodes;

Figure 5 is a partially sectioned side view of the electrode assembly mounted in the electrode body; and, Figure 6 is a plan view of the assembled electrode body.

Figure 1 shows a partially sectioned view of the charge electrode 1 which is generally tubular in shape and which is connected to a conductor 2 which has an insulation 3, after insertion within a supporting insulating cup 4, the electrode l being soldered to the conductor 2 as usual.

Figure 3 shows a circular disk-like phase detector electrode 5 similarly soldered at 6 to a conductor 7 which has a surrounding insulating sleeve 8 and around which is provided a shield 9 with an outer insulator 10. The shield 9 is connected by a wire 11 to a disk-like shield plate 12, again by soldering, at 13.

Figure 3 is similar to Figure 2, but shows a velocity detecting disk-like electrode 14 soldered at 15 to a conductor 16 which has a surrounding insulating sleeve 17. A pair of shield plates 18, 19 are soldered, at 20,21, to respective wires 22,23 which extend from a shield conductor 24 and around which is provided an external insulating sheath 25. The disk electrodes 5 and 14 and their respective shield plates 12, 18, 19 are assembled as shown in order that they can be stacked as shown in Figure 4. Figure 4 shows the stack of charge electrode 1 in its cup 4 positioned on top of, in order, the shield plate 12 phase detector electrode 5, shield plate 18, velocity detector electrode 14 and shield plate 19. These components are disposed in one half of a hollow mould (not shown) which has a generally cylindrical passageway with annular grooves around it disposed to position, accurately, the various electrodes and shield plates. After the components have been placed in the first mould half the second mould half is brought to the first mould half and thereafter the components are united by the injection into the spaces between and around the electrodes, shield plates etc. of an adhesive such as a two-part epoxy adhesive 26. Once the adhesive has cured, the electrode assembly is located (as seen in Figure 5 and Figure 6) in an electrode body 27 which is formed with a main cavity 28, a side cavity 30 and a connecting cavity 29. The side cavity 30 is a blind cavity and has three holes 31 through which the connector cables for the electrode extend after assembly. The electrode assembly (Figure 4) is then mounted in the main cavity 28 as shown in Figure 5, the connecting cables extended sideways through the cavity 29 and into the side cavity 30 and through the apertures 31. Further adhesive 26 is then injected into the electrode body around the cables and electrode assembly within the cavities in the body 27 in order to fix the electrode component firmly in position within the body in order to complete the assembly.

Claims

1. A method of manufacturing an electrode assembly for an ink jet printer, which comprises disposing, in a mould body having a passage defined therethrough, a plurality of disk electrodes (5,14) and a cylindrical electrode (1) in longitudinal alignment at fixed positions, injecting an adhesive (26) into the mould around the electrodes, (1,5,14) allowing the adhesive (26) to set, removing the assembly of electrodes from the mould, inserting the assembly into a bore (28) in an electrode-supporting body (27) , and injecting adhesive (26) into the body (27) to fix the electrode assembly (1) therein.

2. A method according to claim 1, wherein the mould body comprises a plurality of annular recesses around the passage and the electrodes (5,14) are disposed in respective recesses to fix their position relative to one another.

3. A method according to claim 1 or claim 2, wherein the electrodes (5,14) are ring-shaped and the mould body is split to enable insertion of the electrodes and removal of the fixed assembly.

4. A method according to any of the preceding claims, wherein a longitudinal slot (29) is formed through the body (27) and assembly in order to provide a passageway from the centre of the electrodes (5,14) to the outside of the electrode body, so that it can move laterally into position once a stream of droplets has been established in a printhead.

5. A method according to any of the preceding claims, wherein intermediate earthed shields (12,18,19) of similar shape are provided in positions between the electrodes, being moulded in position in the same steps as defined in any of the preceding claims.

6. An electrode assembly and electrode body (27) manufactured by the method defined in any of the preceding claims.