Internal circulation high-speed printing head for PCB or FPC character printing equipment

Abstract

The present invention provides an internal circulation high-speed printing head applied to PCB or FPC character printing equipment, by arranging a first fluid groove and a second fluid groove on the first plane of a substrate, and arranging a plurality of connecting grooves between the first fluid groove and the second fluid groove; a plane groove connected to the connecting groove is concavely arranged on the second plane of the substrate, an upper cover plate is covered on the first plane, and a first piezoelectric crystal corresponding to the connecting groove is arranged on the upper cover plate; a lower cover plate is buried in the plane groove of the second plane, and micropores and a second piezoelectric crystal corresponding to the connecting groove are arranged on the lower cover plate; the first piezoelectric crystal and the second piezoelectric crystal are configured as follows: when an electric field is applied, the first piezoelectric crystal and the second piezoelectric crystal are deformed in opposite ways. When the first piezoelectric crystal and the second piezoelectric crystal are deformed from the upper and lower ends of the connecting groove into the connecting groove, the ink will be squeezed more, so as to meet the needs of the PCB character inkjet printer for high ink volume and faster printing speed.

Description

Technical Field

[0001] The invention relates to the technical field of PCB character printing, and in particular to an internal circulation high-speed printing head applied to PCB or FPC character printing equipment. Background Art

[0002] As the speed of electronic product updates and iterations becomes faster and faster, the demand for PCB / FPC production is also increasing.

[0003] The traditional PCB production method is mainly based on screen printing technology, which has gradually failed to meet the production needs of modern PCBs. Inkjet printing technology, as a new technology, can be directly used to print anti-corrosion and anti-plating graphics, print characters, and even print circuits. Compared with the traditional screen printing process, PCB inkjet printers using inkjet printing technology are fully in line with the development direction of industrial policies of energy saving, emission reduction, consumption reduction, and efficiency improvement, and have gradually become the mainstream of PCB production.

[0004] The application of PCB inkjet printers in PCB production is mainly in the areas of graphic transfer, embedding passive components and directly forming conductive lines. In the application of PCB graphic transfer, character printing is a relatively mature application. The nozzles used in existing PCB character inkjet printers are piezoelectric nozzles. The piezoelectric crystals in the piezoelectric nozzles will deform under the applied voltage. When the voltage with image information is applied to the nozzle, the volume of the device storing the liquid in the nozzle will suddenly change, and the ink will be ejected from the fixed small holes, thereby forming characters on the circuit substrate.

[0005] Piezoelectric nozzles use an internal circulation technology in their applications, that is, the ink circulates in the channel to prevent the pigment particles in the nozzle from settling and clogging the nozzle. The piezoelectric crystal is set on the side wall or end of the channel. When ink droplets need to be sprayed, an electric field is applied to the piezoelectric crystal to drive the piezoelectric crystal to deform, thereby squeezing the ink in the channel out of the nozzle and spraying it onto the PCB substrate.

[0006] Compared with wire lines, PCB characters have lower requirements, consume more ink, and require faster printing speed. However, ink is generally viscous. When the ink flows at high speed in the channel, the piezoelectric crystal needs to exert greater force on the ink when squeezing the high-speed flowing ink in order to quickly and effectively press the ink out of the nozzle. The existing nozzles are not good at high-speed printing of large amounts of ink, so they need to be improved. Summary of the invention

[0007] The invention provides an internal circulation high-speed printing head applied to a PCB or FPC character printing device, so as to meet the needs of the PCB character inkjet printer for a high ink volume and a faster printing speed.

[0008] The technical solution of the present invention is as follows:

[0009] An internal circulation high-speed printing head for PCB or FPC character printing equipment, comprising:

[0010] A substrate, the substrate having a first plane and a second plane, a first fluid groove and a second fluid groove are arranged on the first plane, a plurality of connecting grooves arranged along the length direction of the first fluid groove and the second fluid groove are arranged between the first fluid groove and the second fluid groove, and a planar groove connected to each of the connecting grooves is arranged on the second plane;

[0011] an upper cover plate, the upper cover plate covers the first plane, and a surface of the upper cover plate away from the first plane is provided with first piezoelectric crystals corresponding to the connecting grooves one by one;

[0012] and a lower cover plate, the upper cover plate covers the planar groove, is provided with micro holes corresponding to the connecting grooves in a one-to-one correspondence, and a surface of the upper cover plate away from the planar groove is provided with second piezoelectric crystals corresponding to the connecting grooves in a one-to-one correspondence;

[0013] The first piezoelectric crystal and the second piezoelectric crystal are configured such that when an electric field is applied, the first piezoelectric crystal and the second piezoelectric crystal deform in opposite ways.

[0014] In some embodiments of the present invention, each of the communicating grooves corresponds to two micro-holes, each of the communicating grooves corresponds to two first piezoelectric crystals, and the first piezoelectric crystals correspond to the micro-holes.

[0015] In some embodiments of the present invention, the length of the connecting groove is 10 mm-20 mm, and the distance between two microholes corresponding to the same connecting groove is 5 mm-10 mm.

[0016] In some embodiments of the present invention, a central axis of the microhole intersects with a deformation midline of the first piezoelectric crystal.

[0017] In some embodiments of the present invention, when an electric field is applied, the squeezing force of the first piezoelectric crystal on the ink is greater than the squeezing force of the second piezoelectric crystal.

[0018] In some embodiments of the present invention, a ratio of Young's modulus between the upper cover plate and the lower cover plate is greater than 1.

[0019] In some embodiments of the present invention, the upper cover plate is made of any one of polyimide, polyamide or polyetheretherketone, and the lower cover plate is made of polytetrafluoroethylene.

[0020] In some embodiments of the present invention, the thickness of the upper cover plate is 70-150 microns, and the thickness of the lower cover plate is 50-70 microns.

[0021] In some embodiments of the present invention, the sum of the thicknesses of the lower cover plate and the second piezoelectric crystal is less than the depth of the planar groove.

[0022] In some embodiments of the present invention, the print head also includes a base, a first surface of which is joined to the base, and has an avoidance groove for avoiding the upper cover plate and an ink inlet cavity and an ink return cavity connected to the first fluid groove and the second fluid groove.

[0023] The beneficial effects of the present invention are:

[0024] The first fluid groove and the second fluid groove are arranged on the first plane of the substrate, and a plurality of connecting grooves are arranged between the first fluid groove and the second fluid groove; a plane groove corresponding to the connecting groove is recessed on the second plane of the substrate, an upper cover plate is covered on the first plane, and a first piezoelectric crystal corresponding to the connecting groove is arranged on the upper cover plate; a lower cover plate is buried in the plane groove of the second plane, and micropores and a second piezoelectric crystal corresponding to the connecting groove are arranged on the lower cover plate; and the first piezoelectric crystal and the second piezoelectric crystal are configured so that when an electric field is applied, the first piezoelectric crystal and the second piezoelectric crystal are deformed in opposite ways. Thus, during printing, an electric field can be applied to the first piezoelectric crystal and the second piezoelectric crystal, so that the first piezoelectric crystal and the second piezoelectric crystal are deformed into the channel, thereby squeezing the ink out of the channel. Due to the use of upper and lower end extrusion, the channel is squeezed more, and more ink can be squeezing out of the channel faster, meeting the needs of the PCB character inkjet printer for high ink volume and faster printing speed.

[0025] Moreover, compared with the previous side printing structure in which the piezoelectric crystal is arranged on the inner side wall of the groove, the structure provided by the present invention is easier to implement. Specifically, during manufacturing, the entire piezoelectric crystal can be bonded to the upper cover plate and the lower cover plate, and then the piezoelectric crystal can be cut to form independent piezoelectric units. The cover plate is then bonded to the connecting groove to close the connecting groove to form a connecting channel, which greatly reduces the manufacturing difficulty of the printing head. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of an exploded view of an embodiment of the present invention.

[0027] Figure 2 FIG. 4 is a schematic structural diagram of a substrate in one embodiment of the present invention.

[0028] Figure 3 FIG. 4 is another schematic diagram of the structure of a substrate in an embodiment of the present invention.

[0029] Figure 4 It is a schematic diagram of the cooperation between the upper cover plate and the base in one embodiment of the present invention.

[0030] Figure 5 FIG. 1 is a schematic diagram of the structure of a base in one embodiment of the present invention.

[0031] Figure 6 FIG. 1 is a schematic diagram of ink flow in one embodiment of the present invention.

[0032] Figure 7 FIG. 4 is another schematic diagram of the flow of ink in one embodiment of the present invention.

[0033] Figure 8 for Figure 6 Partial cross-sectional view at AA in the middle.

[0034] Fig. 9 FIG. 1 is a schematic diagram of ink jetting in one embodiment of the present invention.

[0035] Fig.10 Another schematic diagram of ink jetting in one embodiment of the present invention

[0036] Fig.11 for Figure 6 Partial cross-sectional view at the middle BB.

[0037] Fig.12 Schematic diagram of a first piezoelectric crystal ejecting ink in a channel according to an embodiment of the present invention.

[0038] Fig.13 Schematic diagram of two first piezoelectric crystals ejecting ink in a channel in one embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0040] like Figure 1 As shown, the internal circulation high-speed printing head applied to PCB or FPC character printing equipment provided by the present invention includes a substrate 10, an upper cover plate 20 and a lower cover plate 30.

[0041] like Figure 2 As shown, the substrate 10 has a first plane and a second plane parallel to each other in the Z-axis direction, and the first plane is provided with a first fluid groove 10b and a second fluid groove 10c along the Y-axis. The first fluid groove 10b and the second fluid groove 10c are spaced apart on the X-axis, and a plurality of connecting grooves 10f arranged along the Y-axis are provided in the spaced apart area. Each connecting groove 10f is provided along the X-axis to connect the first fluid groove 10b and the second fluid groove 10c. Thus, as shown in FIG. Figure 6 As shown, when ink is introduced into the first fluid groove, the ink in the first fluid groove flows to the second fluid groove through these connecting grooves. By connecting the first fluid groove and the second fluid groove with the ink cartridge connected to the print head, a circulation loop can be formed, so that the ink in the nozzle can always maintain a flowing state in the nozzle, avoiding the particulate matter in the ink from being deposited in the fluid groove or the connecting groove to cause blockage.

[0042] like Figure 4 As shown, the upper cover plate 20 covers the first plane, closing the first fluid groove, the second fluid groove and the opening of the connecting groove along the Z axis to form the first fluid channel, the connecting channel and the second fluid channel on the substrate 10. Figure 8 As shown, first piezoelectric crystals 22 corresponding to the connecting grooves are arranged on the surface of the upper cover plate 20 facing away from the first plane. The first piezoelectric crystals 22 are located directly above the connecting grooves, and the upper cover plate body between adjacent first piezoelectric crystals 22 is bonded to the end of the groove wall 10e of the connecting groove to support the first piezoelectric crystals 44.

[0043] It should be noted that, in order to facilitate the display of the slot structure of the substrate 10 , the portion of the upper cover plate 20 covering the first fluid slot, the second fluid slot and both ends of the connecting slot is not shown.

[0044] like Figure 3 As shown, a plane groove 10g is recessed along the Z axis on the second plane, and the plane groove 10g is connected with each of the connecting grooves, so that the bottom notch of each connecting groove is exposed outward from the plane groove 10g. The width of the plane groove 10g is smaller than the length of the connecting groove, which is about 2 / 3 of the length of the connecting groove, so that the two ends of the groove wall of the connecting groove are connected to the substrate body, and will not be separated from the substrate body due to the opening of the plane groove.

[0045] The lower cover is buried in the plane groove to close the bottom notch of each connecting groove, thereby forming a plurality of connecting channels arranged along the Y axis on the substrate. At least one micro hole is opened in the lower cover corresponding to each connecting groove so that the ink in the connecting channel can be sprayed out from inside and outside the channel. In order to drive the ink to spray out from inside the channel, Figure 8 As shown, a second piezoelectric crystal 32 corresponding to the connecting grooves is arranged on the surface of the lower cover plate 30 away from the plane groove. Fig.11 As shown, the portion of the second piezoelectric crystal 32 opposite to the microhole is cut away to avoid the microhole.

[0046] In addition, the first piezoelectric crystal and the second piezoelectric crystal are configured such that when an electric field is applied, the first piezoelectric crystal and the second piezoelectric crystal are deformed in opposite ways. Specifically, after the electric field is applied, the middle portion of the first piezoelectric crystal can be concave toward the connecting channel, while the middle portion of the second piezoelectric crystal can be convex toward the connecting channel, squeezing the upper cover plate and the lower cover plate to deform toward the connecting channel, compressing the ink in the connecting channel, and causing the ink to be ejected from the connecting channel.

[0047] In the above-mentioned high-speed printing head, a first fluid groove and a second fluid groove are arranged on the first plane of the substrate, and a plurality of connecting grooves are arranged between the first fluid groove and the second fluid groove; a plane groove corresponding to the connecting groove is recessed on the second plane of the substrate, an upper cover plate is covered on the first plane, and a first piezoelectric crystal corresponding to the connecting groove is arranged on the upper cover plate; a lower cover plate is buried in the plane groove of the second plane, and micropores and a second piezoelectric crystal corresponding to the connecting groove are arranged on the lower cover plate; and the first piezoelectric crystal and the second piezoelectric crystal are configured so that when an electric field is applied, the first piezoelectric crystal and the second piezoelectric crystal are deformed in opposite ways. Thus, during printing, an electric field can be applied to the first piezoelectric crystal and the second piezoelectric crystal, so that the first piezoelectric crystal and the second piezoelectric crystal are deformed into the channel, thereby squeezing the ink out of the channel. Due to the use of upper and lower end extrusion, the channel is squeezed more, and more ink can be squeezed out of the channel faster, meeting the needs of the PCB character inkjet printer for high ink volume and faster printing speed.

[0048] Moreover, compared with the previous side printing structure in which the piezoelectric crystal is arranged on the inner side wall of the groove, the structure provided by the present invention is easier to implement. Specifically, during manufacturing, the entire piezoelectric crystal can be bonded to the upper cover plate and the lower cover plate, and then the piezoelectric crystal can be cut to form independent piezoelectric units. The cover plate is then bonded to the connecting groove to close the connecting groove to form a connecting channel, which greatly reduces the manufacturing difficulty of the printing head.

[0049] In the above embodiment, the first piezoelectric crystal and the second piezoelectric crystal can selectively drive the first piezoelectric crystal and / or the second piezoelectric crystal to deform as needed to control the amount of injection. Fig. 9 As shown, it is possible to select to apply an electric field only to the first piezoelectric crystal 22, so that the first piezoelectric crystal 22 deforms into the connecting channel and a small amount of ink liquid is ejected. Fig.10 As shown, an electric field is applied to the first piezoelectric crystal 22 and the second piezoelectric crystal 32 to compress the space of the communication channel to a greater extent, and more ink liquid is ejected. Through the cooperation of the first piezoelectric crystal 22 and the second piezoelectric crystal 32, each micropore has more optional printing amounts and faster printing response to meet the high-speed printing requirements of different ink amounts.

[0050] As preferably, Fig.11 As shown, in the above embodiment, the number of micropores corresponding to each of the connecting grooves 10f is set to two, and accordingly, the number of first piezoelectric crystals (21, 22) corresponding to each of the connecting grooves 10f is also set to two, and the first piezoelectric crystals (21, 22) correspond to the micropores. Thus, the printing density is increased and characters are formed quickly.

[0051] Optionally, the length of the connecting groove is 10mm-20mm, and the spacing between the two microholes corresponding to the same connecting groove is 5mm-10mm. In this way, two first piezoelectric crystals arranged along the length direction of the groove body can be arranged above the connecting groove, and a sufficient distance can be ensured between the two first piezoelectric crystals, so that the two first piezoelectric crystals can work independently of each other, and avoid one first piezoelectric crystal from affecting the upper cover part on the upper side of the other first piezoelectric crystal when deforming. The spacing between the microholes is maintained at 5mm-10mm, and at the same time, the second piezoelectric crystals arranged on the lower cover part can be kept at a reasonable distance, avoiding mutual influence between the two second piezoelectric crystals.

[0052] Specifically, Fig.12 As shown, the first piezoelectric crystal 21 and the second piezoelectric crystal 31 are deformed into the connecting groove 10f, squeezing the ink in the groove to eject it outward. Fig.13 As shown, the first piezoelectric crystal (21, 22) and the second piezoelectric crystal (31, 32) are deformed into the connecting groove 10f, squeezing the ink in the groove so that it is ejected outward.

[0053] Preferably, in the above embodiment, the central axis of the micropore intersects with the deformation centerline of the first piezoelectric crystal. When the first piezoelectric crystal works alone, the extrusion of the ink by the deformation of the first piezoelectric crystal can be better transmitted to the micropore, so that the ink can be ejected more smoothly.

[0054] Preferably, in the above embodiment, when an electric field is applied, the squeezing force of the first piezoelectric crystal on the ink is greater than the squeezing force of the second piezoelectric crystal. In this way, the ink is squeezed onto the lower cover plate and ejected. The main function of the second piezoelectric crystal during the printing process is to compress the space of the connecting channel, so that the ink tends to be ejected from the micropores, so that the first piezoelectric crystal can squeeze out the micropores quickly and in large quantities.

[0055] Furthermore, in the above embodiment, the ratio of the Young's modulus of the upper cover plate to the lower cover plate is greater than 1, that is, the Young's modulus of the upper cover plate is greater than that of the lower cover plate, and the lower cover plate is easier to deform than the lower cover plate. When the first piezoelectric crystal and the second piezoelectric crystal on the upper cover plate and the lower cover plate simultaneously receive external electric field signals, the lower cover plate deforms before the upper cover plate, thereby avoiding the offset of part of the extrusion force caused by the simultaneous deformation of the two, thereby affecting the ink injection effect in the connecting channel.

[0056] Specifically, the upper cover plate is made of polyimide, polyamide or polyetheretherketone, while the lower cover plate is made of polytetrafluoroethylene with a smaller Young's modulus.

[0057] Furthermore, in the above embodiment, the thickness ratio of the upper cover plate to the lower cover plate is greater than 1. Specifically, the thickness of the upper cover plate is 70-150 microns, and the thickness of the lower cover plate is 50-70 microns. This allows the lower cover plate to complete deformation before the upper cover plate, and allows part of the ink to form suspended droplets at the micropores of the lower cover plate. When the lower cover plate is deformed, the suspended droplets are enlarged and ejected from the micropores, ensuring that the ink can be ejected in large quantities in a short time.

[0058] In addition, if Figure 8 As shown, in the above embodiment, the sum of the thickness of the lower cover plate 30 and the second piezoelectric crystal 32 is less than the depth of the planar groove 10g. The lower cover plate 30 and the second piezoelectric crystal 32 are buried in the planar groove 10g. On this basis, by adding a metal guard plate (not shown) outside the substrate 10, the lower cover plate 30 and the second piezoelectric crystal 32 can be well protected.

[0059] like Figure 1 As shown, in the above embodiment, the printing head further includes a base 40, and a first surface of the base 40 is bonded to the substrate 10. Figure 5 As shown, the base 40 has an avoidance groove 40c for avoiding the upper cover plate 20, and an ink inlet cavity 40a and an ink return cavity 40b connected to the first fluid groove 10b and the second fluid groove 10c. When the number of connecting grooves 10f is large, the length of the first fluid groove 10b and the second fluid groove 10c is long, which is not conducive to connecting with the external pipeline. By setting the base 40, and setting the ink inlet cavity 40a and the ink return cavity 40b at both ends of the first surface of the base 40, and setting the ink inlet groove 10a and the ink return groove 10d arranged along the X axis at both ends of the first surface of the substrate 10, the ink inlet groove 10a is connected to the first fluid groove 10b, and the ink return groove 10d is connected to the second fluid groove 10c; after the base 40 and the substrate 10 are closed and joined, the ink inlet cavity 40a is connected to the ink inlet groove 10a, and the ink return cavity 40b is connected to the ink return groove 10d. Thus, an ink inlet tube 41 connected to the ink inlet cavity 40a and an ink return tube 42 connected to the ink return cavity 40b can be directly arranged on the base 40, so that the print head is connected to the ink supply circuit. Figure 7 shown.

[0060] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An internal circulation high-speed printing head used in PCB or FPC character printing equipment, characterized in that: include: A substrate, the substrate having a first plane and a second plane, a first fluid groove and a second fluid groove are arranged on the first plane, a plurality of connecting grooves arranged along the length direction of the first fluid groove and the second fluid groove are arranged between the first fluid groove and the second fluid groove, and a planar groove connected to each of the connecting grooves is arranged on the second plane; an upper cover plate, the upper cover plate covers the first plane, and a surface of the upper cover plate away from the first plane is provided with first piezoelectric crystals corresponding to the connecting grooves one by one; and a lower cover plate, the upper cover plate covers the planar groove, and is provided with micro-holes corresponding to the connecting grooves one by one, and a surface of the upper cover plate away from the planar groove is provided with second piezoelectric crystals corresponding to the connecting grooves one by one; a portion of the second piezoelectric crystals corresponding to the micro-holes is cut off to avoid the micro-holes; The first piezoelectric crystal and the second piezoelectric crystal are configured such that when an electric field is applied, the first piezoelectric crystal and the second piezoelectric crystal deform in opposite ways.

2. The internal circulation high-speed printing head used for PCB or FPC character printing equipment according to claim 1 is characterized in that: Each of the communicating grooves corresponds to two micro-holes, each of the communicating grooves corresponds to two first piezoelectric crystals, and the first piezoelectric crystals correspond to the micro-holes.

3. The inner circulation high-speed printing head for PCB or FPC character printing equipment according to claim 2 is characterized in that: The length of the connecting groove is 10mm-20mm, and the distance between two microholes corresponding to the same connecting groove is 5mm-10mm.

4. The inner circulation high-speed printing head for PCB or FPC character printing equipment according to claim 2 is characterized in that: The central axis of the microhole intersects with the deformation center line of the first piezoelectric crystal.

5. The internal circulation high-speed printing head used for PCB or FPC character printing equipment according to any one of claims 1 to 3, characterized in that: When an electric field is applied, the squeezing force of the first piezoelectric crystal on the ink is greater than the squeezing force of the second piezoelectric crystal.

6. The inner circulation high-speed printing head used for PCB or FPC character printing equipment according to claim 5, characterized in that: The ratio of Young's modulus between the upper cover plate and the lower cover plate is greater than 1.

7. The internal circulation high-speed printing head used for PCB or FPC character printing equipment according to claim 6, characterized in that: The upper cover plate is made of any one of polyimide, polyamide or polyetheretherketone, and the lower cover plate is made of polytetrafluoroethylene.

8. The internal circulation high-speed printing head used for PCB or FPC character printing equipment according to claim 6, characterized in that: The thickness of the upper cover plate is 70-150 microns, and the thickness of the lower cover plate is 50-70 microns.

9. The internal circulation high-speed printing head used for PCB or FPC character printing equipment according to claim 1, characterized in that: The sum of the thicknesses of the lower cover plate and the second piezoelectric crystal is smaller than the depth of the planar groove.

10. The internal circulation high-speed printing head used for PCB or FPC character printing equipment according to claim 1, characterized in that: It also includes a base, the first surface of which is connected to the base, and has an avoidance groove for avoiding the upper cover plate, and an ink inlet cavity and an ink return cavity connected to the first fluid groove and the second fluid groove.

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