A method for manufacturing a liquid jet recording head, a liquid jet recording head manufactured by such method, and a liquid jet recording apparatus having such head mounted thereon

Abstract: A method for manufacturing a liquid jet recording head comprises the steps of obtaining a laminated body by laminating a liquid path formation layer (2) forming liquid paths on a metallic base board (1) having discharge energy generating elements on it, forming an orifice surface by cutting the laminated body thus obtained, and grinding the orifice surface thus formed by use of a cutting tool or a milling cutter. With this method that uses a metallic base board (1), it is possible to obtain a high-performance yet an inexpensive liquid jet recording head without any defects on the orifice surface, which contributes to implementing more stabilized liquid discharge.

Description: The present invention relates to method of manufacturing a liquid jet recording head used for a liquid jet recording apparatus of a bubble jet type or the like that discharges recording liquid (ink) from orifices (discharge ports) as droplets. Related Background Art A liquid jet recording apparatus of a bubble jet type or the like is powerful against external disturbances, and provides a good frequency of liquefaction. Therefore, it is made easier for the apparatus to perform a high-speed printing in good precision, and in colors, among others advantages. The future of this type of apparatus is greatly expected. As shown in Figs. 13A and 13B, a liquid jet recording head used for a liquid jet recording apparatus of the kind is provided with a base board 1001 having discharge energy generating elements, and a nozzle layer (liquid path formation layer) 1002 that forms liquid paths 1002b conductively connected to orifices (discharge ports) 1002a and a liquid chamber. Generally, there are formed on the base board 1001 discharge energy generating elements 1011 by the known means of photo-lithography after an SiO 2 thermal oxidation film 1001a is provided for a monocrystal Si substrate. The surface thereof is covered by an electric insulation layer of SiO 2 , SiC, Si 3 N 4 , or the like, and also, by a protection layer 1001b formed by Ta film or the like for the prevention of damages (such as cavitation erosion) that may be caused to the discharge energy generating elements due to mechanical shock at the time of discharging recording liquid. Here, if necessary, a film of Ta 2 O 5 or the like is provided between the electric insulation layer and the Ta film in order to intensify the contact between them. Also, on the nozzle layer 1002, a glass ceiling plate 1003 and others are arranged with an injection inlet to supply ink or other recording liquid. A liquid jet recording head of the kind is generally manufactured in the following steps of: coating a photoresist on the base board having discharge energy generating elements on it; providing a resist pattern having an inverted shape of the nozzle layer by causing the board thus coated to be exposed and developed; covering the board thus prepared with the glass ceiling plate, and then, injecting molten resin into the space on the circumference of the resist pattern; hardening the resin and forming the orifice surface by cutting it along the predetermined cutting face; and lastly, eluding the resist pattern by use of a solution to cavitate each of the liquid paths on the nozzle layer. In place of the injection molding method described above, there is another method for forming the nozzle layer wherein a photohardening resin is coated on the base board having a resist pattern on it, and then, after the glass ceiling plate is installed on it, a beam is irradiated from above it to harden the resin. In this case, too, such steps are needed that after the resin is hardened, it is cut along the predetermined face, and that the resist pattern is eluded. In order to enhance the productivity of the liquid jet recording heads, a method is adopted as actual steps of the head manufacture that the nozzle layers are laminated for a portion of plural liquid jet recording heads on a base board having a large area, such as a six-inch or an eight-inch wafer as in the case of a semiconductor process, and then, the laminated body is cut off by use of a cutting blade into each individual liquid jet recording head, and that the cutting faces serving as each of the orifice surfaces are ground and polished for finishing. However, in accordance with the conventional techniques described above, the nozzle layers are laminated on a large base board for a portion of plural liquid jet recording heads, and the laminated body thus obtained is cut off into each of the liquid jet recording heads. This cutting process is executed by use of the cutting blade adopted for a usual semiconductor process, which has a cutting width of several tens of µm to one mm. Therefore, as shown in Fig. 14, it is impossible to avoid creating a chipped portion V 1 on the base board 1001 with respect to the cutting face of the liquid jet recording head, which is an orifice surface, a chipped portion V 2 on the nozzle layer 1002, or a crack V 3 on the nozzle layer 1002. Compared with the chipped portion V 2 and the crack V 3 on the nozzle layer 1002, the chipped portion V 1 on the base board, in particular, tends to produce adverse effect on the shapes of the discharge ports 1002a and liquid paths 1002b on the nozzle layer 1002 to a considerable extent. For example, if an Si substrate of 0.5 mm or more in thickness is used for the basic material for the base board 1001, the discharging direction of ink is caused to change conspicuously, thus resulting in the twisted prints and others defects, because the depth of the chipped portion V 1 of the base board 1001 may be as much as 10 µm or more. This is due to the fact that the basic material of the base board is an Si substrate, which is hard and brittle, and the heat accumulation layer, protection layer, and others provided on it are also formed mainly by SiO 2 , which is equally hard and brittle. As a result, the base board has properties as whole that it is extremely easy to be chipped off. In this context, it is referred to the documents US-A-4,657,631 and JP-A-02-048953. The US-A-4,657,631 discloses a method of manufacturing a liquid jet recording head comprising the steps: obtaining a laminated body by laminating a liquid path wall forming layer forming liquid paths on a metallic substrate having discharge energy generating elements thereon; cutting the obtained laminated body so as to optimize the distance between the discharge energy generating elements and the orifices of the liquid flow paths; and polishing and smoothing the orifice surface to optimize the liquid ejection. The post-published document US-A-5,581,285, which claims the priority of JP-A-02-048953, discloses a method of manufacturing a liquid jet recording head comprising the steps: obtaining a laminated body by laminating a partition wall portion forming liquid paths on a substrate of silicon having electrothermal conversion elements thereon; cutting the obtained laminated body by means of a slicing machine using a diamond cutting grinding stone to obtain a pear-like orifice surface of uniform irregularity; regrinding the orifice surface by means of a diamond cutting grinding stone having a finer diamond grain size. In place of regrinding the pear-like orifice surface, it is strongly suggested to spray an ink repellent onto the orifice surface and to smooth the ink repellent by wiping it with a rubber blade. Among the conventional liquid jet recording heads, in an elongated head such as a head of a full-line type, which corresponds to the maximum width of a recording medium such as a recording sheet, a metallic board is often used. This is due to the fact that the currently available configuration of wafers used for the production of the Si substrate described above is only round. Therefore, in case of elongated heads, it is natural that the number of individual heads obtainable therefrom is extremely limited. Also, the costs of Si substrate is comparatively high. For the metallic base board, there are no problems as to the creation of chipped portions and cracking encountered when the Si base board is cut as described earlier. Therefore, the present inventor et al. have tried to produce liquid jet recording heads using metallic base boards in order to solve the problems described above. However, when using a metallic base board, the grinding jig used for grinding each orifice surface after cutting is often caused to be clogged, Thus, a problem is encountered anew that the production yield of liquid jet recording heads cannot be increased easily. SUMMARY OF THE INVENTION In view of the above, it is an object of the invention to provide a method of manufacturing a high-performance liquid jet recording head which is inexpensive or whose production yield is high having no defects such as chipped portions on the orifice surface on the base board with respect to the orifice surface to which orifices (discharge ports) are open. In order to achieve the above object, there is provided a method of manufacturing a liquid jet recording head according to claim 1. In accordance with the invention, burrs created on the orifice surface of the metallic base board in the cutting step can be removed at the same time in the finishing step by using a milling cutter comprising a plurality of different cutting tools. In this way, it is possible to obtain a high-performance liquid jet recording head whose discharge is stabilized with a smooth and perfect orifice surface. Further, since the base board is formed by a metallic substrate, it can be produced at low costs as compared with the method whereby to adopt an Si substrate as a thin material as in the conventional art. In addition to it, the metallic substrate is better in heat radiation. These advantages significantly contribute to providing a higher performance liquid jet recording head at lower costs. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partly broken partial perspective view which shows the principal part of a liquid jet recording head manufactured in accordance with a method which is beyond the scope of the present invention. Figs. 2A and 2B illustrate the steps of manufacture for the liquid jet recording head shown in Fig. 1. Fig. 2A is a partial perspective view showing the principal part of the liquid jet recording head in such steps of manufacture. Fig. 2B is a cross-sectional view taken along line 2B-2B in Fig. 2A. Fig. 3 is a partially enlarged view which shows a part of the orifice surface of the liquid jet recording head represented in Figs. 2A and 2B. Figs. 4A, 4B and 4C illustrate the step of finishing the liquid jet recording head represented in Figs. 2A and 2B. Fig. 4A is a cross-sectional view which schematically shows the liquid jet recording head in such finishing step and a diamond cutting tool. Figs. 4B and 4C are a plan view and a side view showing only the diamond cutting tool, respectively. Figs. 5A, 5B and 5C illustrate the step of finishing the liquid jet recording head using an end mill instead of the diamond cutting tool. Fig. 5A is a cross-sectional view which schematically shows the liquid jet recording head in such finishing step and the end mill. Figs. 5B and 5C are an elevational view and a side view showing only the end mill, respectively. Figs. 6A, 6B and 6C illustrate a side milling cutter and a method for manufacturing a liquid jet recording head in accordance with an embodiment of the present invention. Fig. 6A is a view which illustrates the method for manufacturing a liquid jet recording head. Fig. 6B is an elevated sectional view which shows the side milling cutter. Fig. 6C is a view which illustrates the dimensional relationship between the cutting tool and the finishing tool shown in Fig. 6B. Fig. 7 is a view which shows a cut groove formed by the side milling cutter represented in Figs. 6A, 6B and 6C. Figs. 8A, 8B, 8C and 8D illustrate the cutting and finishing tools of the side milling cutter represented in Figs. 6A, 6B and 6C together with a shank. Figs. 8A and 8B are a side view and an elevational view showing the cutting tool and its shank, respectively. Figs. 8C and 8D are a side view and an elevational view showing the finishing tool and its shank, respectively. Figs. 9A and 9B show one variational example of the side milling cutter in accordance with the embodiment of the present invention. Fig. 9A is the side view thereof. Fig. 9B is a view which illustrates each edge width of the tools. Fig. 10 is a view which shows a cut groove formed by the side milling cutter represented in Figs. 9A and 9B. Figs. 11A and 11B are views which illustrate two other variational examples, respectively. Fig. 12 is a view which schematically illustrates a liquid jet recording apparatus capable of mounting a liquid jet recording head manufactured according to the present invention. Figs. 13A and 13B show liquid jet recording heads in accordance with the prior art. Fig. 13A is a perspective view which shows the principal part thereof. Fig. 13B is a cross-sectional view taken along line 13B-13B in Fig. 13A. Fig. 14 is a partially enlarged elevational view which shows a part of the orifice surface of the liquid jet recording head represented in Figs. 13A and 13B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail. (Illustrative examples) Now, in conjunction with Fig. 1, 2A, 2B, 3, 4A, 4B and 4C, a method will be described which is beyond the scope of the present invention. Fig. 1 shows a liquid jet recording head which comprises a base board 1 having discharge energy generating elements 11, and a nozzle layer (liquid path formation layer) 2 that forms liquid paths 2c conductively connected to orifices (discharge ports on the orifice surface) 21 and a liquid chamber 2c. The base board 1 is formed by an aluminum substrate serving as a metallic base board having a sputtered SiO 2 film provided on it as a heat accumulation layer, and then, by means of known photo-lithography the discharge energy generating elements 11 are formed. The surface thereof is covered by an electric insulation layer formed by SiO 2 , SiC, Si 3 N 4 , or the like, and a protection layer and others formed by a Ta film or the like to prevent any damages (such as cavitation erosion) from being caused to the discharge energy generating elements due to mechanical shocks when recording liquid is discharged. If needed, a Ta 2 O 5 film or the like is provided between the electric insulation layer and the Ta layer in order to intensify the contact between them. Also, there is arranged on the nozzle layer 2, an aluminum ceiling plate 3 and others serving as a second base board having an injection inlet 3a on it to supply ink or other recording liquid. This liquid jet recording head is manufactured in the following steps: As shown in Figs. 2A and 2B, a photoresist is coated on the base board 1 having the discharge energy generating elements 11 on it. The photoresist thus coated is exposed and developed to provide a resist. pattern P having the inverted shape of the nozzle layer 2, and then, the aluminum ceiling plate 3 serving as the second base board is covered on it. A molten resin is injected into the space on the circumference of the resist pattern P, and it is hardened to obtain a laminated body. An orifice surface 21 is formed by cutting this body along the predetermined cutting face. Lastly, by use of solution, the resist pattern P is eluded to cavitate each of the liquid paths 2b and the liquid chamber 2c on the nozzle layer 2 formed by resin as described earlier. In place of a method of the kind, there is another method for forming a nozzle layer, in which a photohardening type resin is coated on a base board having a resist pattern on it, and after installing a transparent ceiling plate on it, a beam is irradiated from above the ceiling plate to harden the resin for the formation of the nozzle layer. In this case, too, there is a need for a step of cutting the hardened resin along the predetermined cutting face, and also for a step of eluding the resist pattern. In order to enhance the productivity of liquid jet recording heads, a method is adopted in the actual steps of head manufacture that the nozzle layer for a portion of plural liquid jet recording heads is formed on a large area substrate such as a six-inch or eight-inch wafer as in the semiconductor process, and the laminated body thus obtained is cut off by use of a cutting blade into each of the liquid jet recording heads, and then, the orifice surface is ground and polished for finishing. As described earlier, an aluminum base board of 2 mm thick is used for the base board 1 instead of the Si base board that has been used for the conventional art. The heat accumulation layer is mainly formed by an SiO 2 film of 2.7 µm thick, and the protection layer is mainly formed by an SiO 2 film of 1.3 µm thick. Also, the ceiling plate 3 is formed by aluminum instead of the glass that has been used for the conventional art. Since the base board 1 is formed by aluminum (a metallic base board), which is an extensible material, it has an advantage that chipped portions are not easily created as compared with the Si base board. Besides, it is inexpensive, while having a good heat radiation, and also, it presents an excellent smoothness, among other advantages. Therefore, using an aluminum base board it is possible to obtain a liquid jet recording head whose discharge performance is stabilized without any chipped portions on its orifice surface. Moreover, with a good heat radiation, it is possible to provide a higher discharge frequency, while obtaining a good adhesive coverage of a thin film pattern of 0.1 µm to several µm in the step of forming discharge energy generating elements, because the surface of the aluminum base board is smooth and flat. This contributes to the provision of another advantage that wiring is not easily broken. Here, instead of aluminum, it may be possible to use copper, brass, or other metals for the metallic base board if only such metallic material has a good extensibility, and cut machinability as well. In the cutting step, it is found that the metal bonded diamond edge conventionally in use is clogged heavily to make cutting impossible. Consequently, a resin bonded GC (silicon carbonate) blade is used. In other words, the cutting is executed by use of a resin bonded GC edge whose grain size is 320; diameter, 125 mm; thickness, 0.9 mm; at 4,600 rpm with a feeding speed of 180 mm/min. On the cutting face (orifice surface) 21, a burr B 1 is created in this stage as shown in Fig. 3 in a shape to close the orifice 2a. Although a resin bonded edge or a resin bonded diamond edge is usable for cutting, the burr B 1 is created equally in either cases. The resist pattern P is yet to be removed, but the burr B 1 in the lower part of the nozzle layer 2 is considerably large. It partly clogs the orifice 2a. Also, chips B 2 are caused on the nozzle layer 2. It is also found that an extrusion B 3 is created on the orifice surface 21 (see Fig. 2B and Fig. 4A). Therefore, as shown in Fig. 4A, a finish cutting is executed by use of a diamond cutting tool T. As shown in Figs. 4B (plan view) and 4C (side view), the diamond cutting tool (JISB10107) T is provided with a diamond tip T 1 for use of the mirror finish of aluminum alloy or the like. Here, it may be possible to use a diamond-tipped milling cutter (JIS0172) or a cemented carbide cutting tool or milling cutter for the finishing cut. By the use of the diamond tip T 1 for finish cutting as described above, it is possible to remove the burr B 1 and the extrusion B 3 created on the orifice surface in the cutting step. The finish cutting is executed in the condition given below. A diamond cutting tool T (diamond curvature: 10 mm) is mounted on a flange F having a diameter of 100 mm. The cutting step is repeated five times each at 4,600 rpm, with a feeding speed of 46 mm/min, and for a biting amount of 10 µm. A liquid jet recording head thus produced is used for printing test with the result that excellent printing properties are obtained. In place of the diamond cutting tool, a cemented carbide cutting tool is also used for finish cutting. In this case, too, the result of a test has shown the excellent printing properties. However, it is found that the diamond cutting tool should preferably be adopted, because using it the unwanted elements that may be created on the orifice surface are smaller. Now, the description will be made of one variational example of the above method. Figs. 5A, 5B and 5C are views which show such examples. In accordance with this example, a liquid jet recording head is manufactured by use of an end mill E having a diamond cutting tool R as shown in Fig. 5A for its finish cutting. Any other aspects than this use of end mill are the same as those described in the first embodiment. With the end mill E, the roughness of the cutter edge is transferred to the orifice surface, because the feeding direction of the base board 1 is the same as the rotational direction of the cutter or it is opposite thereto. Therefore, instead of the usual diamond end mill that uses a sintered compact, the tip R 1 is formed by natural diamond for use as shown in Figs. 5B and 5C, which are the elevated and side views thereof, respectively, in order to make the surface roughness of the orifice surface smaller. Here, the cutting condition is that an end mill of 10 mm diameter having its edge of 5 mm long is used at 15,000 rpm with the feeding speed of 150 mm/min for an amount of bite of 10 µm per cutting step. This step is repeated five times. As compared with the use of a milling cutter, this cutting setup results in a better orifice configuration above the ceiling plate as well as below the base board. Also, an advantage is obtainable that the extrusions remaining on the nozzle layer are smaller. In this respect, each of the finishes obtained by use of the sintered diamond and cemented carbide end mills is examined, with the result that each of them indicates excellent printing properties. However, in consideration of the frequency in which defects are found on the orifice surface, it is preferable to use the sintered diamond to the cemented carbide, and the natural diamond to the sintered diamond. For the materials of the base board and the ceiling plate, it may be possible to use copper, brass, or some other metal that contains aluminum as its main component, besides aluminum itself, if only such metallic material has an excellent cut machinability. Now, as a second variational example, a liquid jet recording head is manufactured in the same manner as the above with the exception of the ceiling plate, which is formed by a phenol resin containing a filler, instead of aluminum. With a filler being contained in the phenol resin, the linear expansion coefficient thereof is made equal to that of aluminum. This ceiling plate has an advantage over the aluminum ceiling plate in that it is easier to be formed to incorporate an ink supplying system in it, and the liquid jet recording head can be manufactured at lower costs accordingly. Also, there is another advantage that both the cutting and the finish cutting are easier to be executed than those required for the aluminum ceiling plate. As the material of the ceiling plate, it may be possible to use a polyetherimide containing a filler or pholyphenylene sulfide containing a filler, which provide a linear expansion coefficient closer to that of aluminum, besides the filler-contained phenol resin. Further, as a third variational example, a liquid jet recording head is manufactured in the same manner as above with the exception of the ceiling plate, which is formed by polysulfone (PSF) instead of aluminum. With the ceiling plate formed by a PSF of ultraviolet transmission type, it becomes possible to use a photohardening injection resin for the formation of a nozzle layer. In this way, a time required for hardening can be shortened significantly. Also, an advantage is obtainable that the inner condition of the nozzles can be observed, among others. However, since the linear expansion coefficient becomes larger than that of aluminum, warping tends to occur during the heating process while manufacturing the liquid jet recording heads in this way. There is a need for a temperature control. Also, there is a tendency that the shape of the ceiling plate is made more convex than that of the aluminum ceiling plate after cutting. Instead of the polysulfone, it may be possible to use a polyethersulfone of ultraviolet type or amorphous polyolefin for the ceiling plate. (Embodiment) In accordance with the above method, the cutting step of a liquid jet recording head, and the finishing step of the orifice surface are separately executed. However, the present embodiment presents a method for manufacturing a liquid jet recording head wherein the cutting step and the finishing step are executed at a time. The structural feature of the present embodiment is to adopt a side milling cutter for cutting the base board. Here, particularly, the side milling cutter is provided with a rotational body, and also, with a plurality of cutting tips held in different positions in the circumferential direction of the rotational body, and also, with driving means to rotate this rotational body. Here, one of the plural cutting tips is provided with a top cutting edge having a larger rotational radius than those of the tips of the other cutting edges. In this way, this side milling cutter serves as a cutting tool to form a cut groove on a work piece, while each of the remaining cutting tools are provided with the side cutting edge serving as finishing cutter to cut the side faces of the cut groove thus formed. In this respect, these finishing cutters may be held on the rotational body stepwise in the width direction of each cutting edge, respectively. Also, the width of cutting edge of the finishing cutter should preferably be larger in the circumferential direction of the rotational body as it is farther away from the one serving as the cutting tool. With the structure thus arranged, the present embodiment can contribute to simplifying the manufacturing steps of a liquid jet recording head, as well as to making the time of manufacturing cycle significantly shorter. Also, a cutting tool and finish tools are held on the same rotational body for revolution. As a result, it is possible to curtail the installation expenditures and maintenance costs to a considerable extent as compared with the separate use of cutting equipment for the cutting step and the finishing step, respectively. Moreover, since the cutting step and the finishing step are executed by each of different cutting tools, the cutting amount of each cutting tool is made smaller as compared with the case where the same cutting tool is applied both to cutting and finishing. Therefore, it becomes possible to enhance the precision remarkably when finishing the orifice surface by use of the cutting tool dedicated only to the finish operation. Further, since the cutting amount is smaller for each of the cutting tools, the width of each cutting edge can be made smaller as a whole. Consequently, there is an advantage that the width of cut groove can be made smaller accordingly, thus making it possible to obtain more numbers of liquid jet recording heads from one substrate. Now, with reference to the accompanying drawings, the description will be made of the above embodiment in accordance with the present invention. Figs. 6A, 6B and 6C illustrate a side milling cutter and a method for manufacturing a liquid jet recording head in accordance with the present embodiment. As a finished product, the liquid jet recording head comprises a base board 1 having discharge energy generating elements, and a nozzle layer (liquid path formation layer) 2 that forms liquid paths conductively connected to the discharge ports (orifices) 2a on an orifice surface 21, and a liquid chamber. The base board 1 is formed by an aluminum substrate serving as a metallic base board having a sputtered SiO 2 film provided on it as a heat accumulation layer, and then, by means of known photo-lithography the discharge energy generating elements are formed. The surface thereof is covered by an electric insulation layer formed by SiO 2 , SiC, Si 3 N 4 , or the like, and a protection layer and others formed by a Ta film or the like to prevent any damages (such as cavitation erosion) from being caused to the discharge energy generating elements due to mechanical shocks when recording liquid is discharged. If needed, a Ta 2 O 5 film or the like is provided between the electric insulation layer and the Ta layer in order to intensify the contact between them. At first, in the same manner known as semiconductor process, a large area substrate 10, such as a six-inch or eight-inch wafer, a nozzle layer 20 for a portion of plural liquid jet recording heads is laminated to produce a laminated body W. By cutting the laminated body W along cutting lines M, each of the liquid jet recording heads is cut off. Here, a side milling cutter 30 shown in Figs. 6B and 6C is used for the simultaneous execution of the cutting step to cut off each of the liquid jet recording heads and the finishing step to perform the surface finish of the orifice face 21 of each liquid jet recording head. The side milling cutter 30 is formed by holding a cutting tool 32 and a finishing tool 33 on the circumference of a circular flange 31 serving as a rotational body that rotates around the center of the rotational shaft O. Both of the tools are mounted outwardly on the same diameter in the diametral direction of the circular flange 31. Both the cutting tool 32 and finishing tool 33 are provided with trapezoidal cutting edges, respectively, and each of them is head on the flange 31 through each of shanks 34 and 35. As shown in Fig. 6C, the bottom width of the trapezoidal cutting edge of the cutting tool 32, that is, the edge width T 1 , is smaller than the edge width T 2 of the finishing tool 33. Also, the tip of the cutting tool 32, that is, the rotational radius R 1 of the top side (leading edge) 32a of the trapezoidal cutting tool is larger than the rotational radius R 2 of the top side 33a at the tip of the trapezoidal cutting edge of the finishing tool 33. When the circular flange 31 rotates by use of driving means (not shown), the cutting edge of the cutting tool 32 executes the cutting operation to cut the laminated body W, that is, a work piece, into each of the liquid jet recording heads by use of the top side 32a and both sides 32b and 32c of the trapezoid thereof, and then, in continuation, the cutting edge of the finishing tool 33 executes finishing operation by use of only both sides (side edges) 33b and 33c to finish the orifice surface 21 of each of the liquid jet recording heads. Fig. 7 illustrates the shape of a cut groove S to be formed on the laminated body during the simultaneous steps of cutting and finishing by the revolution of the circular flange 31 as described above. The tip S 1 of the cut groove S is formed by use of the cutting tool 32, and the side face S 2 of the cut groove S is formed by use of the finishing tool 33. In order not to allow the tip 33a of the finishing tool 33 to cut the top end S 1 of the cut groove S formed by the cutting tool 32, it is necessary to satisfy the following relationships between the revolution of the circular flange 31, that is, the revolution N of the side milling cutter and the feeding speed F, and the rotational radii R 1 and R 2 of the finishing tool 33: (R 1 - R 2 ) > F / N / n where n is the number of tools mounted on the circular flange 31. Here, as shown in Figs. 8A to 8D, guide grooves 34a and 35a are provided for the shanks 34 and 35 of the cutting tool 32 and finishing tool 33. Along these guide grooves, the mounting unit of the circular flange 31 is caused to move relatively to change the amounts of protrusions for the cutting tool 32 and finishing tool 33 in the respective diametral directions, hence adjusting the rotational radii R 1 and R 2 accordingly. In accordance with the present embodiment, the laminated body is cut off into each of the liquid jet recording heads, and then, the finishing step of each orifice surface is executed by the separate tool. As a result, the amount of cutting for each tool can be small, and there is no need for the use of a tool whose edge width is great as in the case of the same tool being used for the cutting and finishing steps at a time. Therefore, while there is no possibility that the number of liquid jet recording heads obtainable from one base board (wafer) is reduced, the finish of each orifice surface can be made in an extremely high precision. Also, with the cutting and finishing tools being mounted on one and the same circular flange for revolution, there is no possibility that the steps of manufacturing liquid jet recording heads become complicated, and that the installation expenditures and maintenance costs become higher unlike the case where each of the cutting and finishing tools should be rotated individually. As a result, the manufacturing costs of liquid jet recording heads are significantly reduced. In this respect, the cutting edge of the cutting tool can be either a sintered diamond or a cemented carbide, but it is desirable to use a natural diamond for the cutting edge of the finishing tool. Now, a specific example will be described. Liquid jet recording heads are cut and finished by use of a natural diamond cutting tool having an edge width of 900 micron, and also, a natural diamond finishing tool having an edge width of 1,000 micron. The revolution N is set at 4,600 rpm with the feeding speed F of 120 mm/min. Now that the number n of tools is 2, the feeding speed f per tool is: f = F / N / n Therefore, it is 13 micron. Now, with a setup being arranged at (R 1 - R 2 ) > 13 micron, the tip of the finishing tool is not allowed to execute any cutting. Here, it is important that the R 1 and R 2 are defined so that even when the revolution N and the feeding speed f change, the setup is always at (R 1 - R 2 ) > f. If the maximum feeding speed Fmax of an apparatus is 300/min, while the minimum revolution Nmin is 2,000 rpm, the maximum feeding amount fmax is 75 micron/tool. Therefore, it should be good enough if only the (R 1 - R 2 ) is adjusted to be 100 micron. Here, each of the orifice surfaces of the liquid jet recording heads thus obtained as finished products is examined with the result: none of them present any burs, scratches, and chippings. The result of printing tests is also favorable. Fig. 9 shows one variational example of the side milling cutter. This cutter has three tools 42 to 44, each having different edge width, mounted on the circumference of a circular flange 41 at equal intervals. Each edge width of the tools 42 to 43 is varied stepwise in the circumferential direction of the circular flange 41 as shown in Fig. 9B. The tool 42 having the smallest edge width is to cut off a laminated body into liquid jet recording heads. The remaining two tools 43 and 44 are to finish each of the orifice surfaces. In this case, as shown in Fig. 10, the shape of a cut groove U formed on the laminated body V has two stages U 1 and U 2 at its top. Like this, a plurality of finishing tools may be arranged. Also, instead of tools having different edge widths, it may be possible to use tools 52 to 54 having the same edge width as shown in Fig. 11A, which are staged to be shifted in the direction of edge width, that is, in the axial direction of the circular flange when mounted thereon. In this case, a cut groove is formed by the tool 52, which is the forerunner, and only one side of the orifice surface of the cut groove is finished by the remaining two tools 53 and 54. Further, as shown in Fig. 11B, tools 62 to 66 having the same edge width may be mounted on a circular flange in the direction of the edge width by shifting each of them alternately. With this arrangement, it is possible to finish both sides of the orifice surface of the cut groove. Now, with reference to Fig. 12, the description will be made of a liquid jet recording apparatus to which a liquid jet recording head manufactured according to the present invention is applicable. In Fig. 12, reference numeral 101a to 101d designate each of line type liquid jet recording heads (hereinafter referred to as a head), respectively. These heads are fixedly supported in parallel to each other by a holder 102, which serves as a supporting member, at given intervals in the direction indicated by an arrow X. On the bottom end of each of the heads 101a to 101d, 3,456 discharge ports are arranged downward in one line at an interval of 16 discharge ports/mm in the direction indicated by arrows Y. With this arrangement, it is possible to record in a width of 216 mm. These heads 101a to 101d are of the type that discharges recording liquid by use of thermal energy. The discharge thereof is controlled by a head driver 120. In this respect, a head unit is structured, which includes the heads 101a to 101d and the holder 102, and the head unit moves in the top and bottom directions by head moving means 124. Also, each of the caps 103a to 103d arranged adjacently to the lower part of each of the heads 101a to 101d correspondingly is provided with an ink absorbent such as sponge in its interior, respectively. The caps 103a to 103d are fixedly supported by a holder (not shown). Then, a cap unit is structured, which includes the holder and caps 103a to 103d. The cap unit moves in the direction indicated by the arrow X by cap moving means 125. To each of the heads 101a to 101d, cyan, magenta, yellow, and black ink are supplied from ink tanks 104a to 104d through each of the ink supply tubes 105a to 105a, respectively, thus making color recording possible. Also, the ink supply is made by utilization of capillary phenomenon created by the discharge ports of each head, and the liquid level of each of the ink tanks 104a to 104d is arranged lower by a specific distance than the position of discharge ports. A belt 106 is carrier means to carry a recording sheet 127, which serves as a recording material, and formed by a chargeable seamless belt. The belt 106 is drawn around a driving roller 107, idle rollers 109 and 109a, and a tension roller 110 by way of a given path, and then, connected to the driving roller 107. The belt runs by a belt driving motor driven by means of a motor driver 121. Also, the belt 106 runs in the direction indicated by the arrow X directly underneath the discharge ports of the heads 101a to 101d. Here, its lower side deviation is suppressed by means of a fixedly supporting member 126. On the lower part where the belt 106 shown in Fig. 12, a cleaning unit 117 is arranged to remove paper particles and others adhering to the surface of the belt 106. An electrifier 112 that charges the belt 106 is turned on and off by means of an electrifier driver 122. The recording sheet 127 is adsorbed to the belt 106 by electrostatic adsorption when the belt is charged. In the front and rear of the electrifier 112, pinch rollers 111 and 111a are arranged, which press a recording sheet 127 on the belt 106 to carry it in cooperation with the idler rollers 109 and 109a. Recording sheets 127 in a sheet feeding cassette 113 is fed out one by one by the rotation of a sheet feeding roller 116. Then, by means of the carrier roller 114 and the pinch roller 115, which are driven by the motor driver 123, the sheet is carried to an angled guide 113 in the direction indicated by the arrow X. The angled guide 113 has an angled space that allows the recording sheet 127 to bend. After recording, the recording sheet 127 is delivered to a tray 118 to receive delivered sheets. The head driver 120, head moving means 124, cap moving means 125, the motor drivers 121 and 123, and the electrifier driver 122 are all controlled by a controller 119. Of the liquid jet recording methods, the present invention demonstrates particularly excellent effects when it is applied to a recording head and a recording apparatus of the so-called ink jet recording method that performs recording by forming flying droplets by utilization of thermal energy. Regarding the typical structure and operational principle of such method, it is preferable for the present invention to adopt those which can be implemented using the fundamental principle disclosed in the specifications of U.S. Patent Nos 4,723,129 and 4,740,796, for example. This method is applicable to the so-called on-demand type recording system and a continuous type recording system as well. To briefly describe this recording method, discharge signals are supplied from a driving circuit to electrothermal transducing elements, which serve as discharge energy generating elements, disposed on a liquid (ink) retaining sheet or liquid path. In other words, in accordance with recording information, at least one driving signal is given in order to provide recording liquid (ink) with a rapid temperature rise so that film boiling phenomenon, which is beyond nuclear boiling phenomenon, is created in the liquid, thus generating thermal energy to cause film boiling on the thermoactive surface of the recording head. Since an air bubble can be formed from the recording liquid (ink) by means of the driving signal given to an electrothermal transducing element one to one, this method is particularly effective for a recording method of on-demand type. By the development and contraction of the bubble, the liquid (ink) is discharged through a discharge port to produce at least one droplet. The driving signal is more preferably in the form of pulses because the development and contraction of the bubble can be effectuated instantaneously and appropriately. The liquid (ink) is discharged with quicker response. The driving signal in the form of pulses is preferably such as disclosed in the specifications of U.S. Patent Nos. 4,463,359 and 4,345,262. In this respect, the temperature increasing rate of the thermoactive surface is preferably such as disclosed in the specification of U.S. Patent No. 4,313,124 for an excellent recording in a better condition. The structure of the recording head may be as shown in each of the above-mentioned specifications wherein the structure is arranged to combine the discharging ports, liquid paths, and the electrothermal transducing elements (linear type liquid passages or right-angled liquid passages). Besides, the structure such as disclosed in the specifications of U.S. Patent Nos. 4,558,333 and 4,459,600 wherein the thermal activation portions are arranged in a curved area is also included in the present invention. Furthermore, the present invention is effectively applicable to the structure disclosed in Japanese Patent Laid-Open Application No. 59-123670 wherein a common slit is used as the discharging ports for plural electrothermal transducing elements, and to the structure disclosed in Japanese Patent Laid-Open Application No. 59-138461 wherein an aperture for absorbing pressure wave of the thermal energy is formed corresponding to the discharge ports. Further, the present invention is effectively applicable to a recording head of full-line type having a length corresponding to the maximum width of a recording medium recordable by the recording apparatus. For the full-line recording head, it may be possible to adopt either a structure whereby to satisfy the required length by combining a plurality of recording heads or a structure arranged by one recording head integrally formed. In addition, the present invention is effectively applicable to an exchangeable recording head of a chip type that can be electrically connected with the apparatus main body, the ink supply therefor being made possible from the apparatus main body, when mounted on the apparatus main body or to the use of a cartridge type recording head provided integrally for the recording head itself. Also, it is preferable to additionally provide a recording head with recovery means and preliminarily auxiliary means because these additional means will contribute to making the effectiveness of a recording apparatus more stabilized. To name them specifically, these are capping means, cleaning means, suction or compression means, preheating means such as electrothermal transducing elements or heating elements other than such transducing elements or the combination of those types of elements, and a predischarge means for performing discharge other than the regular discharge with respect to the recording head. Also, as the recording modes of a recording apparatus, the present invention is not only applicable to a recording mode in which only one main color such as black is used for recording, but also, extremely effective in applying it to an apparatus having plural recording heads provided for use of at least one of multiple colors prepared by difference colors or a full-color prepared by mixing colors, irrespective of whether the recording heads are integrally structured or structured by a combination of plural recording heads. For the present invention, the most effective method applicable to various kinds of ink referred to in the preceding paragraph is the one that enables the film boiling method to be effectuated as described above. Furthermore, as the mode of the recording apparatus of the present invention, it may be possible to adopt a copying apparatus combined with a reader, in addition to the image output terminal for a computer or other information processing apparatus. Also, it may be possible to adopt a mode of a facsimile equipment provided with transmitting and receiving functions. In the embodiments of the present invention described above, while the ink has been described as liquid, it may be an ink material which is solidified below the room temperature but soften or liquefied at the room temperature or soften or liquefied within a temperature range of the temperature adjustment, that is, not lower than 30°C but not higher than 70°C applicable to the general liquid jet recording. In other words, if only ink is liquefied at the time of giving recording signals for use, any one of them should be good enough for use. In addition, while positively preventing the temperature from rising due to thermal energy by the use of such energy as an energy to be consumed for changing states of ink from solid to liquid, or by the use of the ink which will be solidified when left intact for the purpose of preventing the ink from being evaporated, it may be possible to adopt for the present invention the use of an ink having a nature of being liquefied only by the application of thermal energy, such as an ink capable of being discharged as ink liquid by enabling itself to be liquefied anyway when the thermal energy is given in accordance with recording signals, and an ink which will have already begun solidifying itself by the time it reaches a recording medium. In such a case, it may be possible to retain ink in the form of liquid or solid in the recesses or through holes of a porous sheet such as disclosed in Japanese Patent Laid-Open Application No. 54-56847 or 60-71260 in order to keep ink to be in the facing position with respect to the electrothermal transducing elements. In the present invention, the most effective method for the various kinds of ink mentioned above is the one that enables the film boiling method to be effectuated as described above.

Claims: A method of manufacturing a liquid jet recording head comprising the following steps: obtaining a laminated body by laminating a liquid path formation layer (2) forming liquid paths (2b) on a metallic base board (1) having discharge energy generating elements (11) thereon; and cutting said obtained laminated body so as to form an orifice surface (21), and finishing said orifice surface (21), characterized in that the cutting step and the finishing step are executed at the same time by using a milling cutter comprising a plurality of different cutting tools (32,33; 42-44; 52-54; 62-66). A method according to claim 1, wherein said metallic base board (1) is formed by a material having aluminum or copper as its main component. A method according to claim 1, wherein a second base board (3) of metal or resin is provided on said liquid path formation layer (2). A method according to claim 3, wherein said second base board (3) is formed by a material containing as the main component at least one of aluminum, copper, polysulfone, polyethersulfone, amorphous polyolefin, phenol resin, polyetherimide, and polyphenylene sulfide. A method according to claim 1, wherein said milling cutter is provided with a diamond edge. A method according to claim 1, wherein said cutting and finishing steps are executed by a side milling cutter provided with a rotational body (31; 41) holding said cutting tools (32,33; 42-44; 52-54; 62-66) in different positions in the circumferential direction thereof, and driving means for driving said rotational body; and one of said tools (32; 42; 52; 62) is provided with a tip edge having a larger rotational radius than that of each remaining tool (33; 43,44; 53,54; 63-66) to form a cut groove (S; U) on a work piece as a cutting tool, while each of the remaining tools has a side edge to cut the side face of said cut groove as a finishing tool. A method according to claim 6, wherein the edge widths of the finishing tools (43,44) of said side mill cutter are the larger the farther from said cutting tool (42). A method according to claim 6, wherein the finishing tools (53,54; 63-66) of said side mill cutter are held on said rotational body in a shifted state in the direction of each edge width, respectively. A method according to claim 1, wherein orifices (2a) for discharging ink are formed in said orifice surface (21) to obtain the liquid jet recording head (101a-101d). A method according to claim 9, wherein said discharge energy generating elements (11) are electrothermal transducing elements. A method according to claim 9, wherein the obtained liquid jet recording head (101a-101d) is mounted on a liquid jet recording apparatus comprising: supply means (120) for supplying signals to the discharge energy generating elements (11) of said liquid jet recording head (101a-101d); and carrying means (106) for carrying a recording medium (127) so as to enable it to face said liquid jet recording head (101a-101d).

Inventors: SUZUKI TOSHIO, SUZUKI, TOSHIO
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1996
Main classification: B41J2
IPC codes: B41J2