JPH11227205A - Ink jet arrangement print head and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high production yield by cutting a wafer square to a plurality of channel plate elements, preparing a nozzle plate having orifices defining nozzles arranged by a different pitch from a pitch of the elements and arranging the nozzles to coincide within a section of one opening end of a channel. SOLUTION: A sheet of printing paper passes a print head 10 in a direction at right angles to an array of nozzles 26. When electricity is supplied to all actuators periodically with the same timing, a regular matrix pattern of dots is printed on the sheet. An ink jet printer comprises some print heads 10 arranged alternately properly and operating with a proper timing. Additional dots print a gap between nozzles 26 of the other print head, thereby achieving high resolution. Channel plate elements 36 can easily be manufactured by regularly cutting linear grooves at a wafer surface with neglecting a boundary of the channel plate elements to be formed on the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet array print head and a method for manufacturing the same.

[0002]

BACKGROUND OF THE INVENTION U.S. Pat. No. 5,410,340 discloses an ink jet array printhead including a channel plate comprising a plurality of channel plate elements, each channel plate element comprising a plurality of parallel channels separated from each other by partitions. Each channel has an open end forming a nozzle, and the channel plate elements are arranged in parallel so that the nozzles form a linear array.

[0003] This known device is a so-called bubble jet printhead, the heating element of which is associated with each channel in order to heat the ink in the channels in a timely manner, thereby forming bubbles in the ink and causing ink droplets to form. Generate sufficient pressure to blow out of the nozzle. The manufacturing process of this printhead forms heating elements arranged in rows on the surface of a silicon wafer, cuts square into tiles of the same size as the channel plate elements, and matches the position of the heating elements with the position of the channels And sandwiching the tile and channel plate elements to perform the same.
At least the first and last heating elements of each tile are displaced slightly inward to provide sufficient space for the square cuts and to avoid damage to the heating elements adjacent to these square cuts, so that the corresponding channels Slightly offset from the center of the

[0004] EP-A-0402172 discloses an array printhead in which the pressure required to eject an ink drop is generated by a piezoelectric actuator. The actuators are each provided with a flexible plate interposed on the ink channel, which is bent by the expansion / contraction stroke of the piezoelectric actuator so that a pressure wave is generated in the ink volume in the channel. In this type of printhead, the width of the end of the channel forming the nozzle must be reduced such that the width of the channel itself is greater than the width of the nozzle.

[0005] A similar device is found in Applicant's 199 Applicant.
It is disclosed in co-pending European Patent Application No. 96202043.4, filed July 18, 6th. It is, of course, desirable that the linear array of nozzles be arranged at a constant pitch through the printhead. When the channel plate has an integral structure, this can be easily achieved by forming the channels and nozzles in a regular pattern. It is further desirable that the nozzle pitch be made as small as possible to achieve high image resolution. As a result, the width of the channel, and in particular the width of the partition separating it, must be made very small. In certain instances, the width of the septum is on the order of only 40 μm.
In the manufacture of such fine structures, it is inevitable that accidental manufacturing errors render the entire device unusable. As the number of channels increases, the likelihood of such errors also increases, thus lowering the manufacturing yield.
For the manufacture of large array printheads, e.g., printheads extending across the width of the page to be printed, it is desirable to divide the channel plate into a plurality of separate channel plate elements, thereby causing a defect. It is sufficient to replace defective elements without discarding the entire channel plate.

[0006] The channel plate elements must be properly squared to achieve a continuous nozzle with a constant pitch. However, this results in the problem that only limited space is available for the outer wall limiting the channel adjacent to the squared end of the channel plate element. The thickness of these outer walls should not be more than half the thickness of the partition separating the individual channels in the channel plate. It is problematic to manufacture an outer wall that is only half of this thickness because the thickness of the septum is already quite small, which also increases the likelihood of a defect.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a channel plate which is composed of a plurality of channel plate elements, wherein the nozzles are arranged at a constant pitch across the boundaries of the channel plate elements and which is manufactured with a high production yield. The present invention is to provide an ink jet array print head having the same.

[0008]

The above object is achieved by the features set forth in claim 1. Suitable methods of manufacturing such a printhead are set forth in claims 7 and 8. According to the invention, the channels of each channel plate element are arranged at a constant pitch smaller than the pitch of the nozzles.

[0009] As a result, the position of the nozzle relative to the channel varies across the width of the nozzle plate element. Generally, there is a zone in the center of the nozzle plate element, where the nozzles are located near the center of the width of the associated channel, while in other zones of the channel plate element, the nozzles are lateral from the center of the channel. Offset. This offset increases in proportion to the distance of the nozzle from the zone in the center of the channel. Thus, if the width of the channel plate element is infinite, it will be skipped in a series of nozzles, resulting in a "blind channel" that does not overlap with any of the nozzles. These "blind channel" arrangements are appropriate to make a square cut to separate the channel plates into respective channel plate elements, thereby providing sufficient space to make the outer walls of adjacent channels thicker. is there.

[0010] Further details of the printhead according to the invention are set out in the dependent claims. In a preferred embodiment, the thickness of the outer wall adjacent the end of the channel plate element is the same thickness as the partition. This eliminates fluctuations in the course of droplet generation in the various channels that would otherwise fluctuate the mechanical strength of the walls limiting the channel. If the printhead is of the type using piezoelectric actuators, these actuators are arranged at the same constant pitch as the channels. Preferably, the actuators are integrated into a number of actuator members, each comprising a plurality of actuators. At this time, the boundaries between the actuator members coincide with the boundaries between the channel plate elements.

The center-to-center distance between the two channels on each side of the boundary between different channel plate elements is equal to twice the pitch of the channels in the channel plate element. This has the advantage that the actuator members can be dimensioned and arranged ignoring the boundaries between the channel plate elements. This is because the pitch of the actuator always matches the pitch of the channel. Actuators which are located at the boundaries of the channel plate elements and thus have no channels associated therewith are of course not actuated and are provided as support members which carry the repulsion generated by the active actuator.

One method of manufacturing a printhead according to the present invention forms channels and nozzles on the surface of a wafer such that the pitch of the channels is smaller than the pitch of the nozzles, and obtains a plurality of channel plate elements from one and the same wafer. Cutting the wafer at an appropriate position. When the nozzles are formed on the surface of the wafer, the distance between the centers of two nozzles located on each side of the location of the square cut is equal to, less than or greater than the pitch of the other nozzles. These differences can either be provided by providing a suitable gap between adjacent channel plate elements, or by increasing the width of the square cut so that the channel plate elements are closer together when the distance is greater than a specified pitch. Will be corrected.

An alternative method of manufacturing a printhead according to the present invention is to form a channel in the surface of a wafer, square cut the wafer into a plurality of channel plate elements, and form the channel plate elements to form a complete channel plate. Providing nozzle plates having orifices arranged in parallel and defining nozzles arranged at a pitch different from the channel pitch, channeling the nozzle plates such that each nozzle coincides with the cross section of one open end of the channel. It consists of steps provided before the board.

In this case, the nozzle plate is divided into several elements by the same pattern as the channel plate or a different pattern.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. The print head 10 shown in FIG.
It comprises a channel plate 14, a flexible plate 16, an actuator system 18, and a back plate 20.

As shown more clearly in FIG. 2, a plurality of parallel channels 22, 24 are formed on the upper surface of the channel plate 14, preferably made of graphite. As shown in FIG. 1, the nozzles 2 and
6 are formed. The open upper sides of the channels 22, 24 and the nozzle 26 are covered with a flexible plate 16, for example a thin glass plate. The actuator system 18 has a comb-like structure and is formed by a plurality of piezoelectric actuator members 28 each consisting of a number of parallel fingers 30, 32 each having a lower end coupled to the flexible plate 16. The upper ends of the fingers are connected by a bridge portion of the actuator member, and the back plate 20 includes various actuator members 28.
Is fixed to the upper surface of the bridge portion.

The fingers 30, 32 are connected to the channels 22,
24 in parallel. The piezoelectric material of the fingers 30 is polarized so that these fingers are provided as piezoelectric actuators. These actuators are arranged in pairs, and the fingers 32 are interposed between the actuators 30 of each pair, and are provided as support members that carry the operating force of the actuators.

As shown in FIG.
Each of the zeros is disposed on one of the channels 22, 24, while the support member 32 is disposed directly on a partition 34 that separates the individual channels. The print head 10 further comprises an ink supply system for supplying liquid ink to each of the channels 22 and 24, and the
0 and an electric control means. These components are generally known to those skilled in the art and are therefore not shown or described herein. Actuator 3 by operation
When one of the zeros is powered, it first undergoes a contraction stroke such that the portion of the flexible plate 16 connected to this actuator is bent upwards and additional ink is drawn into the associated channel. The actuator then undergoes an expansion stroke such that the flexible plate 16 is bent down into the channel and the liquid in this channel is compressed so that the ink droplets are ejected from the nozzle 26.

The channel plate 14 comprises a plurality of other channel plate elements 36, only one of which is shown generally in FIG. The channel plate elements 36 are arranged in parallel, the boundaries between these elements being indicated by the reference numeral 38.
As shown in FIG. 2, the nozzles 26 are arranged at a constant pitch Dn through the printhead, ie the distance between two adjacent nozzles belonging to the same channel plate element 36 is two Equal to the distance between the nozzles. Thus, a sheet of printed paper passes through the printhead 10 in a direction perpendicular to the rows of nozzles 26, and a regular matrix pattern of dots is formed on the paper when all actuators are periodically powered at the same timing. Printed on In certain applications, an ink jet printer consists of several printheads 10 that are properly interleaved and operate at the right time, so that additional dots are printed in the gaps between nozzles 26 of other printheads. , Thereby achieving a high resolution.

For purposes of illustration, the channel plate element 36 of FIGS. 1 and 2 is shown as comprising only eight channels 22,24. However, actually, the number of channels per channel plate element is considerably large, for example, 150 or more. Channel 2 belonging to the same channel plate element 36
2, 24 are also arranged at a constant pitch Dc. However, as shown in FIG.
6 is slightly smaller than the pitch Dn. The width of the nozzle 26 is significantly smaller than the width of the channels 22,24. In a practical example, the width of the nozzle is 40 μm, while the width of each channel is about 300 μm. In the case of the channel 22 arranged at the center position of the channel plate element 36, the nozzle 26
Is substantially located at the center of the channel, while the nozzle is offset more outward from the center of the channel as it approaches the lateral edge of the channel plate element. As a result, two channels 24 located on each side of the boundary 38
Is much larger than the regular pitch Dc of the channel. This has the advantage that, despite the constant pitch Dn of the nozzles, the channels 24 close to the boundary 38 are limited by an outer wall 40 having the same thickness as the partition 34 between the channels 22 in the channel plate element.

In the embodiment shown, each channel plate element 36 is positioned on the support plate 12 such that the distance between the nozzles of the channels 24 adjacent the boundary 38 is equal to Dn and a small gap is formed between the channel plate elements. Have been. Alternatively, this gap may be filled with a suitable spacer element, or the outer wall 40 may be made thicker so that the channel plate elements 36 can directly balance one another.

In the embodiment shown in FIGS. 1 and 2, there is a one-to-one relationship between the channel plate element 36 and the actuator member 28. In a variant, a large actuator member is provided which extends over the boundary between the channel plate elements 36. In this case, the distance Dc 'is preferably equal to twice Dc, so that the actuator member can have a uniform pattern of fingers 30, 32 ignoring the boundary 38 of the channel plate element.

A plurality of channel plate elements 36 form channels 22, 24 and nozzles 26 on the surface of a large wafer portion 42, a top view of which is shown in FIG. 3, and a square cut 44 to form each channel plate element. Can be produced efficiently. Channels 22, 24
Is formed on the wafer, the distance between the channels 24 is appropriately selected in view of the width of the square cut 42.
If desired, the thickness of the outer wall 40 can be made larger or smaller than the thickness of the septum 34. Preferably, however, the thickness of the outer wall 40 is greater than half the thickness of the septum 34.

Since there is a one-to-one correspondence between the actuator members 28 and the channel plate elements 36, and the actuators 30 are arranged in pairs in the embodiment shown in FIG. 1, each channel plate element 36 has an even number. Has a channel. Preferably, the actuator 30 is separated from the partition wall 34 and the outer wall 40 of the channel to avoid sharp bending of the flexible plate 26 when the flexible plate is displaced by the actuator. This is why the fingers 30, 32 in FIG. 1 are arranged in an irregular pattern, which is problematic from a manufacturing point of view.

FIG. 4 shows a modification in which all the fingers 30, 32 of the actuator member 28 are arranged at equal intervals. In this case, the channels 46, 48 of the channel plate 14 are arranged in pairs corresponding to the pairs of actuators 30. Sufficient spacing of the actuator from the partition walls and end walls of the channels is achieved by two channels 46,48.
Are slightly displaced outwardly with respect to the associated support finger 32. Thus, the channels 46, 48 of the channel plate element 36 are no longer arranged at a constant pitch. However, it is possible to determine the effective pitch Dc to be half the distance between adjacent pairs of the two channels 46,48. This effective pitch Dc is constant over the entire channel element 36.

In the above embodiment, the nozzle 26 was formed on the channel plate 14 by converging the channel at the end forming the nozzle. 5 and 6, the channel 50 is formed by a straight groove, and the nozzle 52 is the channel plate 1.
4 shows an embodiment defined by orifices formed in another nozzle plate 54 fixed to the front surface of the flexible plate 16, etc. The channel plate element 36 according to this embodiment is easily manufactured by cutting a regular pattern of linear grooves in the surface of the wafer 42 ignoring the boundaries between the channel plate elements formed thereon. A square cut 44 is then formed along the centerline where the groove 50 is to be removed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a part of a print head according to a first embodiment of the present invention.

FIG. 2 is a plan view of a channel plate of the print head shown in FIG.

FIG. 3 is a plan view of a wafer on which the channel plate shown in FIG. 2 is made;

FIG. 4 is a sectional view of a main part of a print head according to another embodiment of the present invention.

FIG. 5 is a horizontal sectional view of a print head according to still another embodiment of the present invention.

6 is a plan view of a wafer on which the channel plate of the print head shown in FIG. 5 is formed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Print head 12 Support plate 14 Channel plate 16 Flexible plate 18 Actuator system 20 Back plate 22, 24, 46, 48, 50 Channel 26, 52 Nozzle 30, 32 Finger 28 Piezoelectric actuator member 36 Channel plate element 38 Boundary 40 Outer wall 42 Wafer 44 Square cut 50 Groove 54 Nozzle plate Dc Channel pitch Dn Nozzle pitch

Claims (9)

[Claims] 1. A channel plate (14) comprising a plurality of channel plate elements (36), each channel plate element comprising a plurality of parallel channels (22, 24; 50) formed therein, each channel having an open end forming a nozzle (26; 52), and the channel plate element being an ink jet array printhead in which the nozzles are arranged in parallel to form a linear array. There are channels (22, 24; 5)
0) is larger than the width of the nozzle (26; 52), and the channels of each channel plate element (36) are arranged at a constant effective pitch (Dc) smaller than the nozzle pitch (Dn). Inkjet printhead. 2. The channel (24) adjacent to the boundary (38) between the different channel plate elements (36) has a partition (3).
2. An ink jet array printhead according to claim 1, wherein the outer wall is limited by a thickness greater than half the thickness of 4). 3. The ink-jet printhead as claimed in claim 2, wherein the thickness of the outer wall (40) is equal to or greater than the thickness of the partition (34). 4. Two channels (2) on each side of a boundary (38) between different channel plate elements (36).
4. An ink jet array printhead according to claim 1, wherein the center-to-center distance (Dc ') between them is equal to twice the pitch (Dc) of the channels in the channel plate element. 5. An ink jet arrangement according to claim 1, wherein each channel (22, 24; 50) is associated with a piezoelectric actuator (30) which pressurizes a liquid ink contained in the channel. Print head. 6. An ink-jet printhead as claimed in claim 1, wherein the nozzles (52) are defined by orifices formed in the nozzle plate (54). 7. Channels (24) forming parallel channels (22, 24) on the surface of the wafer (42);-Channels (24) defining ends of each group to form a plurality of channel plate elements (36). A square cut (44) between the nozzles (26) of the various channel plate elements (36)
Comprises the steps of arranging channel plate elements (36) in parallel to form an array having a constant pitch (Dn), each channel having a reduced end to form a nozzle (26); The channels (22, 24) have a constant pitch (Dn) where the nozzles (26) have a constant pitch (Dn) and the channels (22, 24) have a constant pitch (Dc) that is smaller than the pitch of the nozzles. Are offset outwardly with respect to the center of the width of the channel, the offset increasing towards both ends of the group.
A method for producing an ink jet array printhead according to any one of the preceding claims. 8. Forming straight parallel channels (50, 50) having open ends on the surface of the wafer (42) and arranged in groups with a constant pitch (Dc) of the channels; Separate from each other and separate channel plate elements (3
6) making square cuts (44) of the wafer to form:-channel plate elements (36) arranged in parallel;-nozzle orifice pitch (Dn) greater than channel pitch (Dc) Forming a linear array of nozzle orifices (52) in the plate (54);-channels (5) in the nozzle plate element (36) such that each nozzle orifice (52) communicates with one of the channels.
7. The method of claim 6, further comprising the steps of providing a channel plate (54) before the open end of (0). 9. All channels (50, 50 ') formed in the wafer (42) have a constant pitch, and some of the channels (50) are at least partially cut by making a square cut (44). An ink jet array printhead according to claim 8, wherein said ink jet printhead is removed.