Process for producing an ink jet recording head

Abstract: An ink jet recording head is produced by forming in a first substrate (308) a plurality of orifices (317) for ejecting an ink droplet and a reference object for registration; forming in a second substrate (307) ejection energy generating elements (315) for supplying energy for ejecting the ink placed in liquid passages (314) communicating with the orifices (317); and joining the first substrate 308 and the second substrate (307) together on the basis of the reference object for registration.

Description: The present invention relates to a process for producing an ink jet recording head and more particularly to a process for producing orifices in the ink jet recording head. Ink jet recording is a non-impact recording method which is almost free from noise generation during recording which is capable of high-speed recording and which enables to perform recording without requiring any special operations for fixing onto an ordinary paper. Of the currently known various recording methods, this method is very useful. Wide varieties of proposals have been put forward for this method and improvements have been applied to it. These efforts have led to some commercially available products, whereas some ideas are still on the way to commercialization. Ink jet recording method is one in which ink droplets are ejected by various mechanisms and are deposited it on a recording medium such as a paper, so as to perform recording. The applicant of the present invention has also made a proposal on a novel method related to an ink jet recording. This novel method was proposed in Japanese Patent Application Laying-open No. 118798/1977, and its fundamental principle is outlined as follows: Thermal pulses as information signals are applied to the ink introduced in an ink passage that can accommodate the ink. As a result, the ink generates a vapor bubble and produces an actuating force during its growth and contraction. This force causes the ink to be ejected as the droplets from orifices communicating with the ink passage, whereafter the droplets are deposited on a recording medium to perform recording. This method provides the orifices in a high-density, multi-array layout which can easily fit for high-speed recording as well as color recording. In addition, the apparatus employed in this method is simpler in construction than conventional apparatuses. Hence, a recording head can be reduced in size as a whole and is suitable for mass-production. This method can also easily provide a wide-rage recording head in which many orifices are arranged by taking advantage of remarkable IC technologies and microscopic processing techniques and of an increase of reliabilities in the semiconductor field. Thus, the method is broad in the scope of applications. As shown in Fig. 1, the ink jet recording head for use in ink jet recording is composed of a first substrate 101 (hereinafter to be referred to as a heater board) equipped with electro-thermal converting elements and a second substrate 102 which has grooves for forming a liquid chamber accommodating the ink and ink passages by joining the first substrate 101 to the second substrate 102. The second substrate 102 integrally has an orifice plate 104 which includes ink ejection outlets 109, that is, orifices, communicating with the ink passages (the second substrate will hereinafter to be referred to as a grooved top plate). The heater board 101 is adhered and fixed to a supporting base plate 103 with the use of an adhesive. The grooved top plate 102 is bonded with the heater board 101 in such a manner that the electro-thermal converting elements disposed on the heater board 101 register with the grooves for ink passages formed in the grooved top plate 102. The orifice plate 104 of the grooved top plate 102 is disposed so as to project forward and downward like an apron from a front end surface of the supporting base plate 103. Grooves 103A are formed in a part of the area of the supporting base plate 103 which is covered by the orifice plate 104, more specifically, in the area that is covered by right and left end portions of the orifice plate 104. The ink is supplied from an ink feed member 105 through an ink feed port 102a provided in an upper portion of the grooved top plate 102. The ink feed member 105 has a projecting bar and is fixed to the supporting base plate 103 by inserting this projecting bar into a through hole provided in the supporting base plate 103 and thermally caulking the through hole. The gaps 110a and 110b, between the ink feed member 105 and the heater board 101, and, between the ink feed member 105 and the grooved top plate 102, as well as a joining area with a tiny gap between the orifice plate 104 and the front end surface of the supporting base plate 103 which is to be sealed with an adhesive, constitute an adhesion space which is filled with a sealing compound from above the ink feed member 105 through the grooves 103A. The ink jet recording head as described above has several problems with production as indicated below. 1) In Fig. 1, the joining area between the orifice plate 104 and the front end surface of the supporting base plate 103 has so small gap that the sealing compound often fails to reach the gap, particularly, its central portion, in a sufficient amount. To avoid this problem, it has been a customary practice to lower the viscosity of the sealing compound. The lowering of its viscosity, however, causes the sealing compound to go out of holes provided in the supporting base plate 103, i.e. a mounting hole for a presser spring to be mounted to provide a close contact between the second substrate 102 with the ink passages and the heater board 101, and a hole for insertion of an ink supply pipe of the ink feed member 105 for suppling the ink from an ink tank, as well as a gap in a posterior portion of the ink feed member 105. As a result, the amount of the sealing compound may be insufficient. Moreover, a protrusion which will serve as a reference object when the ink jet recording head is mounted on the carriage may be coated with the sealing compound, thus deteriorating the accuracy and precision of mounting, thereby, for instance, causing a recorded line to be curved. Furthermore, the sealing compound may invade the orifices, causing the ink not to be ejected. 2) In bringing the electro-thermal converting elements and the orifices into registration, it has been a customary practice to register them manually using a specialized jig while alternately observing the electro-thermal converting elements and the orifices under a metallurgical microscope. This manual adjustment by an operator for registration of the electro-thermal converting elements and the orifices has the following problems: a) Variations in the manual work cause variations in the accuracy and precision of adjustment. b) Visual measurements and manual operations of the jig for repeated use take much time for adjustment. c) The operator suffers from asthenopia due to the long-term visual measurements, and ultraviolet irradiation for setting the adhesive when fixing the members after registration of the orifices and the electro-thermal converting elements. To solve these problems, the applicant of the present invention proposed an apparatus for performing registration of the orifices without relying on manual work. According to this apparatus, the positions of the electro-thermal converting elements and the positions of the orifices are confirmed with an ITV camera via an optical system, and informations on the positions of them are converted into image signals, which are transmitted to an image processing unit. In the image processing unit, the image signals of the two members are processed and their positional coordinates are calculated. On the basis of the calculated results, the difference in position is determined, and the top plate is moved so that the positions of the electro-thermal converting elements and the positions of the orifices are brought into registration with each other.This conventional apparatus still involves the following problems: Generally, the orifices formed in the. orifice plate integral with the top plate and the grooves for the ink passages of the top plate are arranged in plural numbers with similar shapes. When these members are to be brought into registration in joining the top plate with the heater board while observing the orifices with the ITV camera, the determinations of the orifices to be registered have been impossible with a conventional image processing unit. Consequently, the electro-thermal converting elements and the orifices are generally out of register; the orifice may be positioned at a place where the electro-thermal converting elements are not located, or no orifices may be positioned at a place where the electro-thermal converting elements are located. Such a failure in the accurate registration of the orifices and the electro-thermal converting elements will adversely affect ink ejection performance, and would become the cause of the ink not being ejected in the worst case. Particularly, when the ink jet recording head becomes more accurate, more precise and speedier, the orifices and the grooves for ink passages become micro-sized. This requires the exact registration between the orifices and the electro-thermal converting elements as an indispensable task for the production of the ink jet recording head. 3) When the orifices of the recording head are formed, it has been a common practice to use a laser capable of emitting an ultraviolet radiation such as a fourfold wave of an excimer laser or a YAG laser. The formation of the orifices in this case has been carried out in two roughly manners as follows. a) First, the orifice plate for forming the orifices is joined to an end surface of the top plate where the groove for the ink passages has been formed. Then, the orifices are formed by irradiating a laser beam onto the orifice plate via a mask. The groove for the ink passages is open at the end surface of the top plate, and the formation of the orifices is performed so that the orifices will communicate with the opening. The orifice plate may be formed of a resin film or the like. During the formation of the orifices, the position of the orifice to be formed and the position of the groove for the ink passages are brought into registration. The above-mentioned procedure is shown in Fig. 2. In this drawing, the reference numeral 301 denotes an ultraviolet laser apparatus, 302 a laser beam emitted by the ultraviolet laser apparatus 301, 303 a lens system, 304 a projection mask having aluminum evaporation-deposited thereon which has all or some of the patterns of the orifices and which can be shielded to the laser beam 302, 305 a top plate provided with a groove for the ink passages and a groove for a common liquid chamber, 305A an orifice plate, and 305B a support member for supporting the top plate 305. A movable stage 306 moves the support member 305B horizontally, thereby moving the top plate 305 supported thereon, and eventually adjusting the position of the groove for the ink passages with respect to the laser beams.Details of the ink jet recording head body in which the orifices have been formed in accordance with such a construction are illustrated in Fig. 3.Fig. 3 is a schematic sectional view of the recording head body.In Fig. 3, 408 is a heater board with an electro-thermal converting element patterned, and 411 is an orifice formed in an orifice plate 405A. The reference numeral 414 designates an ink passage, and 415 is an electro-thermal converting element provided in correspondence to the ink passage 414. The ink passage 414 is composed of the groove for the ink passage and the heater board. b) Alternatively, an orifice is formed by irradiating an ultraviolet laser beam from the side where the groove for the ink passage 414 has been formed, onto a member having the top plate 405 and the orifice plate 405A formed integrally. This procedure is illustrated in Fig. 4. Fig. 4 shows a manner in which an ultraviolet laser beam is irradiated from the ink passage side onto the orifice plate formed integrally with the top plate, thereby forming an orifice. The same members as shown in Fig. 2 are indicated by the same reference numerals.The procedure for forming the orifice as mentioned above has been performed in the following manner: A laser beam that has passed the projection mask is irradiated onto the orifice plate to form an orifice. For registration of the laser beam, the shape of the groove for the ink passage is incorporated as image informations by means of an ITV camera, and the position of the groove is confirmed by recognizing the image. Then, the position of the groove for the ink passage is brought into registration via the projection mask with the position where the laser beam is to be irradiated.A third problem with the laser beam machining for forming orifices is as follows: Since there are a plurality of the grooves for the ink passages with the same shape, whichever the above-mentioned methods may be employed, it has been difficult to determine by image processing which of the grooves for ink passages should be registered with the laser beam.For example, it has been conventionally used to form the orifices after counting the number of grooves for the ink passages from the end groove for the ink passage to the aimed groove for the ink passage, or to form the orifice after registering the top plate with a movable stage, and then irradiating the laser beam onto the orifice plate.The former method, however, takes a wasteful time for the formation of the orifices because the number of grooves for the ink passages has to be counted from the end grooves for the ink passages to the aimed groove for the ink passage each time the orifice is to be formed.On the other hand, according to the latter method, if the dimensions of the top plate are varied, the dimensions of the top plate mounting panel have to be varied with response to dimensional variation, or data on how much the movable stage should be moved must be incorporated again into the image recognition apparatus. Thus, the steps for laser beam machining become complicated. 4) Fourthly, there has been the problem that when orifices are to be formed by laser beam machining, their shapes may be different depending on the positions of the orifices arranged. As shown in Fig. 5, a laser beam emitted by a laser oscillation apparatus (not shown) is divided into laser beams L 1 to L n indicated by a plurality of thick arrows as shown in Fig. 5 that have passed the mask.An optical axis 616 k (indicated by a one dot chain line in Fig. 5) of the laser beam L k in the neighborhood of the center of the laser beam, coincides with an axis 620 k of the orifice 611 k , which is a symmetrical axis for the shape of the orifice, but the intensity of the laser beam becomes weaker at a peripheral portion apart from the center of the laser beam. Therefore, when the orifice plate 610 is formed, the shape of the orifice formed is such that its end heads toward the inside where the intensity of the laser beam is strong.This trend is noticeable at orifices 611 1 and 611 n at both end portions. The axes of ink ejection outlets 620 1 and 620 n do not coincide with the optical axes 616 1 and 616 n of the laser beams L 1 and L n and incline toward the center of the orifice. As a result, ink droplets are ejected more inwardly than the direction for ejecting ink droplets in the vicinity of the center of the laser beam. Furthermore, the orifices 611 k-1 , 611 k , and 611 k+1 in the neighborhood of the central axis of the laser beam, and the orifices 611 1 , 611 n at peripheral portions of the laser beam are different in the direction of laser beam machining and have different shapes. This also results in the deterioration of the grade of recorded images.To solve the above-described problems, the following methods have been adopted:The orifice plate is machined only with use of laser beam in the neighborhood of the center of the laser beam to form an orifice. The orifice plate is laser beam machined in such an manner that an optical system thought out so that the intensity of the laser beam at peripheral portions of the laser beam coincides with the intensity in the neighborhood of the center of the laser beam, thereby to form an orifice. According to the method for forming the orifice using only the laser beam in the neighborhood of the center of the laser beam, however, the area where the orifice is formed is narrow, thus making it impossible to form a number of orifices at a time. The formation of multiple orifices requires that the area of laser beam machining be varied frequently, and the orifice plate be machined for many times. Consequently, the machining time is prolonged, and the throughput is decreased. At each laser beam machining, moreover, there tends to be large variations in the positions, shapes and diameters of the orifices, thus lowering the accuracy and precision of machining.The method of working out such an optical system that the intensity of the laser beam is the same in the vicinity of the center of the laser beam and at the peripheral portions of the laser beam has the following disadvantages: Since the construction of the optical system is complicated, many lenses are used, thus making their adjustment difficult and decreasing the throughput. Also, the apparatus is separately needed to adjust the optical system, thereby rising the costs of the orifice formation. 5) Laser beam machining for orifice formation also has the following problems: When a work such as an ink jet recording head is to be laser beam machined to form orifices, the formation of numerous orifices takes much time such a construction in which a laser beam is converged to one point to form orifices one by one. Particularly, much time is required for registration intended for accurate laser beam machining of an orifice, thus lowering remarkably the operational efficiency. To avoid these disadvantages, a laser beam machining apparatus is conceivable in which a desired number of orifices can be perforated in the work, or in which the position of the orifice is measured, and its position can be corrected on the basis of the results measured. In such an apparatus, the orifices with the intended diameter or area are perforated under the conditions where the laser power and/or the irradiation time with response to the thickness of the orifice plate are setted in advance. In the laser beam machining apparatus as mentioned above, however, it may be difficult to perforate orifices with the same diameter or area under the same conditions for long periods of time, owing to variations in the thickness of the orifice plate according to lot differences, changes in the laser power due to changes with time in the laser oscillator and so forth. Hence, regular sampling may become necessary to reset the laser power and/or the irradiation time. This resetting step may lower the operating efficiency of the apparatus. In addition, whenever the lot of the top plate is changed and the interval of the grooves is changed, resetting must be done manually. When many top plates are to be formed from one lot, in particular, an operational step for setting the laser power for each top plate will become necessary. Such preparatory tasks for the apparatus are laborious, thereby lowering the operating efficiency. Furthermore, from the prior art according to JP-A-03121854, an ink jet recording head is known comprising a possibility to recognize the registration from the discharge port formed surface side when groove parts on a second substrate and ink discharge energy generating elements are registered by a method wherein a pattern for registration is provided at a spot which is the vicinity of discharge ports on a substrate having discharge energy generating elements for ink and which is previously designated with respect to the previously mentioned elements. The pattern for registration is in particular provided on a substrate on which the head discharge energy generating elements for ink are also provided. It is an object of the present invention to provide a process for producing an ink jet recording head which permits the accurate registration between the orifice and the electrothermal recording elements. This object is achieved by a method according to claim 1. Further advantageous improvements of the invention are the subject-matters of claims 2 and 3. Fig. 1 is a simplified front view showing an example of a conventional ink jet recording head. Fig. 2 is a schematic constructional view showing a conventional orifice-processing apparatus in which an orifice is formed by laser beam machining. Fig. 3 is a sectional view showing an orifice formed by the laser beam machining apparatus illustrated in Fig. 2. Fig. 4 is a schematic constructional view showing another conventional orifice-processing apparatus in which an orifice is formed by laser beam machining. Fig. 5 is a schematic view of an ink jet recording head showing another conventional mode of forming orifices by laser beam machining. Fig. 6 is a simplified sectional view showing an ink jet recording head which is not part of the present invention. Fig. 7 is a simplified front view showing the ink ejection outlet side as shown in Fig. 6. Fig. 8 is a perspective view showing an example of a supporting base plate constituting the ink jet recording head. Figs. 9A to 9D are perspective views showing other examples of a supporting base plate constituting the ink jet recording head. Fig. 10 is an exploded perspective view of the ink jet recording head. Fig. 11 is a block diagram showing an assembled apparatus for use in the present invention. Fig. 12 is a perspective view of an optical system for detecting the position of the electro-thermal converging element. Fig. 13 is a schematic view of an image obtained with an ITV camera. Fig. 14 is a perspective view of an optical system for detecting the position of the orifice. Fig. 15 is a perspective view showing the situation in which component parts are supplied to the assembled apparatus as shown in Fig. 11. Figs. 16A to 16C are explanatory views showing a method of measuring the deviation of the optical axis with the use of a calibration chart. Figs. 17A and 17B are explanatory views showing a method of measuring the position of the electro-thermal converting element. Figs. 18A to 18G are explanatory views showing a method of conforming the position of the orifice to the position of the electro-thermal converting element with each other, and fixing their positions relative to each other. Fig. 19 is a schematic constructional view of an orifice-forming apparatus for forming an orifice by means of laser beam machining. Fig. 20 is a schematic constructional view of another orifice-forming apparatus for forming an orifice by means of laser beam machining. Figs. 21A and 21B are explanatory views for explaining the top plate member in accordance with the present invention. Figs. 22A to 22C are front views of another orifice plate of the ink jet recording head in accordance with the present invention. Fig. 23 is a schematic perspective view of the ink jet recording head in accordance with the present invention. Fig. 24 is a rear view of still another orifice plate of the ink jet recording head in accordance with the present invention. As illustrated in Fig. 6, an ink jet recording head is composed of a heater board 101 equipped with electro-thermal converting elements, and a second substrate 102 which is joined to the heater board 101 to form recesses and projections constituting a liquid chamber 107 accommodating an ink, and ink passages 108. The second substrate 102 integrally has an orifice plate 104 which includes orifices 109 communicating with the ink passages 108 for ejecting the ink (the second substrate will hereinafter be referred to as a grooved top plate). The heater board 101 is fixed to a supporting base plate 103 with the use of an adhesive. The grooved top plate 102 is joined to the heater board 101 in such a manner that the electro-thermal converting elements disposed on the heater board 101 will register with the ink passages 108 of the grooved top plate 102. The orifice plate 104 of the grooved top plate 102 is disposed so as to project forward and downward like an apron from a front end surface of the supporting base plate 103. The ink is supplied from an ink feed member 105 through an ink feed port 102a provided in an upper portion of the grooved top plate 102. The ink feed member 105 has a projecting bar (not shown), and is fixed to the supporting base plate 103 by inserting this projecting bar into a through hole provided in the supporting base plate 103 and thermally caulking the through hole. The gaps 110a and 110b (see Fig. 7) between the ink feed member 105 and the heater board 101 and between the ink feed member 105 and the grooved top plate 102 as well as a joining area with a tiny gap between the orifice plate 104 and the front end surface of the supporting base plate 103 which is to be sealed with an adhesive, are filled with a sealing compound as an adhesion space. A neighborhood of the orifice plate 104 which constitutes the ink jet recording head is about 30-40 µm in thickness, but desirably becomes thicker toward a lower portion of the supporting base plate 103 and has a thickness of 0.2 mm in the present embodiment. In view of the costs and ink resistance of the materials, thermoplastic resins such as polyimide, polyether ether ketone, or polysulfone can be cited as examples of the materials for the grooved top plate 102 having the orifice plate 104. In the present embodiment, polysulfone with a small amount of heat deformation at high temperatures was used. In Fig. 7, the shaded portion represents the area filled with the sealing compound. As illustrated in Fig. 8, the supporting base plate 103 has grooves 103A formed at the right and left end portions of the area hung over by the orifice plate, and also has grooves 103B formed within an area, where the heater board 101 is to be bonded, and extending beyond this area. The groove 103B is 0.5 mm wide, 0.5 mm deep, and 1 mm in the dimension beyond said area. The thickness of the adhesive is 0.04 mm so that the adhesive usable for the heater board 101 is not to fill up the groove 103B. The groove 103B is not restricted to this size, and may be of any size which permits a thoroughly satisfactory sealing with the adhesive. The heater board 101 is fixed onto the supporting base plate 103 with the use of the adhesive, and the grooved top plate 102 is fixed onto the heater board 101 so that the electro-thermal converting elements disposed on the heater board 101 and the ink passages 107 of the grooved top plate 102 can be registered with each other. The grooved top plate 102 has the orifice plate 104, and the orifice plate 104 is disposed like an apron in front of the front end surface of the supporting base plate 103. The ink feed member 105 is fixed to the supporting base plate 103 by inserting a projecting bar (not shown) provided in the ink feed member 105 into a through hole provided in the supporting base plate 103, and thermally caulking the through hole. In this case, uniform gaps 110a and 110b are formed between the orifice plate 104 and the ink feed member 105. In this embodiment, the gaps 110a and 110b are within the range form 0.1 to 0.2 mm. The sealing compound is poured through a pour port (not shown) in an upper portion of the ink feed member 105, thereby sealing a wire bonding for transmitting electrical signals, and simultaneously sealing the gaps 110a and 110b between the orifice plate 104 and the ink feed member 105. Then, the sealing compound passes through the grooves 103A and 103B provided in the supporting base plate 103, and completely seals the gapped area between the orifice plate 104 and the front end surface of the supporting base plate 103. That is, the shaded portion as shown in Fig. 7 is filled with the sealing compound. The sealing compound in the present embodiment is a two-part setting polyurethane adhesive which permits the admission of little air into the liquid chamber 107 and which is suitable for the sealing of the wire bonding as mentioned above. Its available viscosity is within the range form 3,000 to 7,000 cps and making the viscosity, making a higher value than that of the prior art. The groove 103B formed in the upper surface of the supporting base plate 103 can be press-molded in the case of mass production. A plurality of the grooves 103B may be formed, and in this case, these grooves may be arranged in a parallel or in a radial form. The shape of this groove may be square or semicircular in cross section. Figs. 9A to 9D show examples of its shape. Irrespective of the number and shape of the grooves 103B, it is necessary to determine the method of applying the adhesive for the heater board 101, the thickness of the adhesive, etc. so that the adhesive may not fill up these grooves. As described above, the supply of the sealing compound into those gaps can be facilitated by the grooves provided in the supporting base plate 103 below the heater board 101 with regard to the sealing of the gaps between the front end surface of the supporting base plate and the orifice plate region. Hence, the use of a high-viscosity sealing compound can be achieved in the present invention. Embodiment 1 Fig. 10 is an exploded perspective view of the ink jet recording head in accordance with the present invention. In Fig. 10, the reference numerals 1105a, 1105b and 1105c denote electro-thermal converting elements provided at predetermined positions of a heater board 1102. The heater board 1102 is provided on a support member 1101. A top plate member 1103 is constituted of an integral combination of an orifice plate 1103A where orifices 1106a, 1106b and 1106c are open, and a top plate 1103B where the grooves for the ink passages and a common liquid chamber are provided. An ink jet recording head is constituted by joining the top plate member 1103 with the heater board 1102 together by use of adhesives 1104a and 1104b. The joining of the top plate member 1103 and the heater board 1102 requires the registration of these members. A mechanism of positional adjustment for this purpose will be described below. Fig. 11 is a block diagram showing an assembled apparatus for use in the present embodiment. The support member 1101 onto which the heater board 1102 is fixed is gripped by a support member 10 for gripping jig. The support member 10 is provided to be movable in the Y, Z and X directions via a portion 11 for generating joint force by means of a Y stage 5a, a Z stage 6a and an X stage 7a, respectively. The portion 11 generates a pressure in contact with the top plate member 1103 and the heater board 1102, thus bringing the top plate member 1103 and the heater board 1102 into close contact. The top plate member 1103 is mounted to a spacer 8 via the top plate members 9a and 9b for gripping jigs. The spacer 8 is mounted to a surface plate 1 so as to be movable by a Y stage 2a, a Z stage 3a and an X stage 4a. To move the heater board 1102 for registration, there are used the Y stage 5a for moving it in the Y direction, the Z stage 6a for moving it in the Z direction, and the X stage 7a for moving it in the X direction. That is, the position of the heater board 1102 is determined primarily by the Y stage 5a, Z stage 6a and X stage 7a. To move the top plate member 1103, there are used the Y stage 2a for moving it in the Y direction, the Z stage 3a for moving it in the Z direction to move the top plate member 1103 used and the X stage 4a for moving it in the X direction. The Y stage 2a, Z stage 3a and X stage 4a determine the position of the top plate member 1103. That is, the positions of the orifices 1106a, 1106b and 1106c are determined primarily by these stages. An optical system for detecting the positions of the electro-thermal converting elements 1105a, 1105b and 1105c is composed of an objective lens 31, an objective lens holder 32, an illumination member 33a, a optical system 34 for discriminating focal situation, a lens-barrel 35, and an ITV camera 36. This optical system is mounted to the surface plate 1 via a supporting column (not shown). The optical system 34 mentioned above transmits a signal to for detecting focal situation to a control computer 50 via a focal situation detector 70. The ITV camera 36 transmits an image signal to an image processing unit 60 via a signal converter 64. In this way, a mechanism for detecting the positions of the electro-thermal converting elements is constituted. For performing registration, an optical system for detecting the positions of the orifices 1106a, 1106b and 1106c of the orifice plate 1103A is composed of an objective lens 21, an objective lens holder 22, an illumination member 23a, an optical system 24 for discriminating focal situation, a lens-barrel 25, and an ITV camera 26. This optical system is mounted to the surface plate 1 via a supporting column (not shown). The optical system 24 transmits a signal for detecting focal situation to the control computer 50 via a focal situation detector 71. The ITV camera 26 transmits an image signal to the image processing unit 60 via a signal converter 65. In this way, a mechanism for detecting the positions of the electro-thermal converting elements is constituted. Fig. 12 is a perspective view for illustrating the details of the above-described optical system for detecting the positions for the electro-thermal converting elements. When the registration of the electro-thermal converting element 1105 is to be carried out, the support member 1101 is moved in the directions indicated by arrows 5 and 7 as shown in Fig. 12 by operating the Y stage 5a and X stage 7a, respectively, while confirming the position of the electro-thermal converting element 1105 with the ITV camera 36. In Fig. 12, the reference numerals 5, 6 and 7 designate the Y, Z and X directions in which the heater board 1102 is moved. In Fig. 12, the same reference numerals as in Fig. 11 represent the same construction as shown in Fig. 11. Fig. 13 is a schematic view of an image obtained with the ITV camera 36. In Fig. 13, x 1 designates the coordinate value in the X direction as calculated after processing the image obtained with the ITV camera 36 by means of the image processing unit 60. The image processing unit 60 transmits the value of x 1 for the position of the electro-thermal converting element 1105 to the control computer 60, which stores this data. The coordinate value in the Y direction can be obtained in the same manner. On the basis of the coordinate values in the X and Y directions that have been stored, the X stage 7a and the Y stage 5a are moved to move the heater board 1102, thereby performing the registration of the electro-thermal converting element 1105. Fig. 14 is a perspective view illustrating the details of the optical system for detecting the position of the orifice. When the registration of the orifice 1106 is to be carried out, the top plate member 1103 is moved in the directions indicated by arrows 4 and 3 by operating the X stage 4a and Z stage 3a, respectively, while confirming the position of the orifice 1106 with the ITV camera 26. In Fig. 14, the reference numerals 2, 3 and 4 designate the Y, Z and X directions in which the top plate member 1103 is moved. In Fig. 14, the same reference numerals as shown in Fig. 11 represent the same constructions as in Fig. 11. Now, referring to Fig. 11 again, a light guide 45 is installed beside the top plate member 1103. This light guide 45 enables ultraviolet rays emitted by an ultraviolet light source 57 to be projected onto the adhesive 1104 at a joint portion between the top plate member 1103 and the heater board 1102, whereby the adhesive can be set. The image processing unit 60 calculates the positions of the orifice and the electro-thermal converting element on the basis of image signals obtained with the ITV cameras 26 and 36, and transmits this data to the control computer 50. To the image processing unit 60 are connected an ITV monitor 63 for confirming an image measured, a keyboard 62 for entry of an apparatus for adjusting program and inputting data, and a CRT monitor 61 for data display, thereby establishing an man-machine interface. The control computer 50 calculates the data transmitted by the focal situation detectors 70, 71 and the image processing unit 60. On the basis of such data, the control computer 50 drives and controls the stages 2a, 3a, 4a and 5a, 6a and 7a via stage drivers 80 to 85, thereby moving the top plate member 1103 and the heater board 1102 to bring the positions of the heater and the orifice into agreement. These operations are performed on the basis of an operation program stored in a program disk 54. To the control computer 50 are connected an operating panel 56 for operating the assembled apparatus, a keyboard 52 for setting and switching the operation program, a CRT monitor 51 for data display, a printer 53 for data recording, and a data disk 55 for data storage, thereby establishing a man-machine interface. Next, details of assemblage of the ink jet recording head in accordance with the present embodiment will be described by use of Fig. 15. Fig. 15 shows a situation in which when the recording head is to be assembled, the top plate member 1103 and the support member 1101 having the heater board 1102 fixed thereto are supplied to the top plate member for gripping jigs 9a, 9b and the support member for gripping jig 10. In Fig. 15, the top plate members for gripping jigs 9a, 9b and the support members for gripping jig 10 are positioned at places retreated from the position of assembly operation a, by operating the X stages 4a and 7a, thus facilitating automatically or by use of a robot. Then, the X stage 7a is operated to move a calibration chart 40 fixed onto the base plate for gripping jig 10 to the position of assembly operation a. In Fig. 15, the same reference numerals as in Figs. 10 and 11 represent the same members, and for this reason their descriptions will be omitted. Fig. 16A shows a method for calibrating a deviation of the position of detection by mechanism 31 to 36 for detecting a heater position and an orifice detection mechanism 21 to 26 for detecting the orifice position by use of a calibration chart 40. In Fig. 16A, when a corner of the rectangular parallelepiped calibration chart 40 is measured with the mechanism 31 to 36 for detecting the position of the electro-thermal converting elements and the orifice detection mechanisms 21 to 26 in the positional relationship, the images obtained with the ITV cameras 36 and 26 are as shown in Figs. 16B and 16C. In Figs. 16B and 16C, x b and x c designate the coordinate values obtained, when images obtained with the ITV cameras 36 and 26 are processed and calculated by the image processing unit 60. Since x b and x c are the measured results of the same place of the calibration chart 40, Δx 3 = x b - x c is determined by the deviation of the optical axis between the mechanism 31 to 36 for detecting the position of the electro-thermal converting elements and a detection mechanism 21 to 26 for detecting the position of the orifices. Here, the image processing unit 60 transmits the measured values of x b and x c to the control computer 50, which calculates and stores the amount of deviation of the optical axis, Δx 3 = x b - x c . Then, the X stage 7a is operated to move the support member 1101 and heater board 1102 held on the support member for gripping jig 10 to the position of assembly operation a (see Fig. 15). Fig. 17A shows a manner in which the position of the electro-thermal converting element 1105 on the heater board 1102 is measured with the use of the position detection mechanism 31 to 36 for the electro-thermal converting element. In Fig. 16A, the deviation of the heater board 1102 from the focus is measured with the optical system 34 for discriminating the focal situation and the focal situation detector 70, and this data is transmitted to the control computer 50. The computer 50 calculates the amount of deviation, and operates the Z stage 6a, to bring about a focal situation. Then, the deviation of the end of the heater board 1102 from the focus is measured with the optical system 24 and the focal situation detector 71, and this data is transmitted to the control computer 50. The computer 50 calculates the amount of deviation, and operates the Y stage 5a, to bring about a focal situation. This procedure gives a clear image of the electro-thermal converting element 1105 as shown in Fig. 17B. Then, the X stage 4a is operated to bring the top plate member 1103 gripped by the top plates for gripping jigs 9a, 9b to the position of assembly operation a. Figs. 18A to 18G show procedures for conforming the position of the orifice to the position of the electro-thermal converting element, followed by fixing these positions. Since the top plate member 1103, the heater board 1102 and the electro-thermal converting element 1105 are microscopically processed parts, they may be damaged if an excessive force is applied. Hence, an external force to be exerted on the top plate member 1103, the heater board 1102 and the electro-thermal converting element 1105 needs to be minimized during adjustment. The assembly procedure will be described with reference to Figs. 18A to 18G. When the top plate member 1103 is to be brought to the position of assembly operation a, the top plate member 1103 is positioned above the heater board 1102, with determined gaps Δz and Δx secured therebetween as shown in Fig. 18A. The top plate member 1103 and the heater board 1102 can be prevented from being damaged when the top plate member 1103 being moved is slid on the heater board 1102. Then, the top plate member 1103 is moved in the directions of arrows 3 and 2 as shown in Figs. 18B and 18C by means of the Z stage 3a and the Y stage 2a, bringing the top plate member 1103 and the heater board 1102 into contact. Then, the X stage 4a is operated to move the electro-thermal converting element 1105 and the orifice 1106 in the direction of arrow 4, thereby bringing their positions into conformity. At this time, if the thickness of the top plate member 1103 is large, a frictional force produced between the top plate member 1103 and the heater board 1102 is large, thus taking the risk of damaging both members during their registration. If the thickness of the top plate member 1103 is small, on the other hand, a gap appears between the top plate member 1103 and the heater board 1102, making the movement of the top plate member 1103 unstable during registration, and making accurate registration impossible. Hence, the thickness of the. top plate member 1103 needs to be measured. The method for measuring the thickness of the top plate member will be described in the following. In Fig. 18C, when the top plate member 1103 and the heater board 1102 are brought into close contact, the mechanisms 21 to 26 are used to measure the position of the orifice 1106. Fig. 18D shows the situation of measuring the position of the orifice 1106, and an image as shown in Fig. 18E is obtained with the ITV camera 26. In Fig. 18E, z 2 and x 2 designate the coordinate values in the z and x directions, respectively, these values have been obtained by processing and calculating on the image of the orifice 1106 obtained with the ITV camera 26 by means of the image processing unit 60. The image processing unit 60 transmits the measured values z 2 and x 2 to the control computer 50, which in turn calculates the value for t = z 1 - z 2 from the value of z 1 , the position of the top plate member for gripping jig 9b, the position of the orifice Z 2 at this time, whereby the thickness t of the top plate member 1103 is determined. The pressure of contact between the top plate member 1103 and the heater board 1102 can be made constant by moving the Z stage on the basis of the value t. Then, the control computer 50 calculates Δx m , the amount of movement of the orifice on the basis of the already stored values, i.e. the coordinate value x 1 of the heater 1105, the deviation Δx 3 of the optical axis of the position detecting mechanism, and the position x 2 of the orifice measured as shown in Figs. 18D and 18E. Δx m can be calculated as follows: The amount of movement of the orifice Δx m = x 1 - x 2 + Δx 3 . The control computer 50 actuates the X stage 4a on the basis of the value Δx m , bringing the position of the electro-thermal converting element and the position of the orifice into conformity. Then, the Z stage 3a is moved from z 1 to z 3 in the direction of arrow 3 as shown in Fig. 18F. At this time, a pressure is exerted on a portion 11 for generating joining force, which in response to this, generates a resisting force in a direction opposite to the direction of the movement of the Z stage 3a. Since the top plate member 1103 is fixed in place by means of the top plate gripping jig 9b, a stress N is concentrated in the contact portion between the top plate member 1103 and the heater board 1102. This stress N acts as a joining force, securing a close contact between the top plate member 1103 and the heater board 1102. As shown in Fig. 18G, ultraviolet rays are irradiated from the light guide 45 onto the adhesive 104, thereby setting the adhesive. Thus, the registration and assembly of the top plate member 1103 and the heater board 1102 are completed. After each stage has been moved to the positions as shown in Fig. 15, an assembly is discharged automatically or by use of a robot, thereby completing a series of steps for assembling the recording head. Successively, a next top plate member 1103 and a next support member 1101 are supplied to permit an continuous assembly operation. Then, the method of forming orifices will be described. A first method of orifice formation comprises the steps of joining the orifice plate to an end surface of the top plate which has been processed to have grooves for ink passages and then of irradiating a laser beam onto the orifice plate through the mask, thereby forming orifices. Fig. 19 is a schematic constructional view of an orifice forming apparatus for processing an orifice by the use of a laser beam. In Fig. 19, the laser beam is irradiated onto the orifice plate at its front surface. The reference numeral 201 designates an ultraviolet laser machine, 202 a laser beam irradiated by the ultraviolet laser machine 201, 203 a lens system, 204 a mask with all or some of patterns of the orifice, 1102 a heater board, and 5a, 6a and 7a stages for moving the heater board 1102 in the Y, Z and X directions. The second method for forming orifices is to irradiate an ultraviolet laser beam onto a top plate member 1103 composed integrally of a top plate and an orifice plate from its rear surface with grooves for the ink passages formed. Fig. 20 is a schematic constructional view showing another orifice forming apparatus for forming an orifice with the use of a laser beam. In this drawing, the same elements as shown in Fig. 19 designate the same reference numerals. The ultraviolet laser beam source for use is a KrF excimer laser apparatus, which produces a pulsed laser beam with a wavelength of 248 nm and a pulse width of 15 nsec. The lens system includes synthetic quartz lenses with an anti-reflection coating. The mask is an aluminum-vapor-deposited projection mask capable of shielding the KrF laser beam. Figs. 21A and 21B show schematic views of the top plate member 1103 in accordance with the embodiment of the present invention. As shown in Fig. 21, the orifices formed in an orifice plate 1103A of the present embodiment include square and round orifices. The orifices of such shapes are obtained by irradiating laser beam onto the orifice plate 1103A through the mask by means of the apparatuses as shown in Figs. 19 and 20. The orifice plate 1103 of the present embodiment is provided integrally with the top plate 1103B as shown in Fig. 21B. Fig. 21A is a schematic rear view of the members of Fig. 21B as viewed in the direction of an arrow A, and Fig. 21B is a schematic perspective view of the orifice plate 1103. As are apparent from Figs. 21A and 21B, the orifice plate 1103A has a square orifice 1106' formed in the center, and round orifices 1106 arranged in a row on both sides of the square orifice 1106'. The reference numeral 1107 is an ink feed port for feeding an ink to the common liquid chamber (not shown). This formation of one orifice different from the other orifices in shape facilitates the aforementioned registration of the electro-thermal converting element 1105 and the orifice 1106. This will be described in more detail below. The square orifice 1106' can be easily discriminated by image recognition on the basis of the data on the different shapes of the other orifices stored in the control computer 50. Since the position of the square orifice 1106' in the orifice plate 1103A has been already known, the square orifice 1106' can be registered in correspondence to electro-thermal converting element 1105. Consequently, the orifice and the electro-thermal converting element become free from deviation unlike the conventional embodiments, thus making it possible to produce a highly reliable ink jet recording head without adversely affecting the ink ejection characteristics. In the present embodiment, the orifice 1106' as a reference object for registration which is different from the orifices 1106 of an ordinary round shape is made into a square shape. However, any shape is acceptable so long as it is different from the round shape. For example, a triangular, hexagonal or trapezoidal shape as illustrated in Fig. 22A to 22C may be used. Embodiment 2 Fig. 23 is a schematic perspective view showing another embodiment of the present invention. In the present embodiment, the procedure for forming orifices using the laser beam is the same as the aforementioned method of orifice formation. In this embodiment, a tiny hole 1218 is formed as a reference object for registration in the vicinity of the orifice 1106 at the stage of laser beam machining. In this case, the tiny hole 1218 is confirmed by image processing in the manner as mentioned above, and then the orifice closest to this hole 1218 is detected. Once this orifice is detected, the electro-thermal converting element and the orifice plate integrated with the top plate are brought into registration for joining in the same manner as in embodiment 2 to produce an ink jet recording head. In this embodiment, the tiny hole 1218 is perforated to detect the position of the orifice, but a cruciform opening as shown in Fig. 24 may be formed. When its shape is to be recognized with an image processing unit, the cruciform opening can be completely distinguished from a dust or a scar because of its characteristic shape, and its shape can be discriminated correctly. In addition, such a shape clearly includes an X component and a Y component in image processing, thus facilitating the detection of its position, and permitting the accurate registration of the electro-thermal converting element with the orifice.

Claims: A process for producing an ink jet recording head comprising a first substrate (1103) provided integrally with an orifice plate (1103A) having a plurality of orifices (1106) for ejecting an ink, and a second substrate (1102) combined with said first substrate (1103) and provided with ejection energy generating elements for supplying energy for ejecting the ink, said process contains the following steps: detecting a reference object (1106', 1218, 216A, 216B) for registration which is provided in said first substrate (101) and which is used when said second substrate (1102) is combined with said first substrate (1103); and joining together said first substrate (1103) and said second substrate (1102) with reference to said detected reference object (1106', 1218, 216A, 216B) for registration, wherein said reference object (1106', 1218) for registration is an opening provided in said orifice plate (1103A), and the opening as the reference object for registration is different in shape or size from the orifice (1106). A process as claimed in claim 1, characterized in that said ejection energy generating elements generate thermal energy to generate a bubble and the ink is ejected accompanied by generating said bubble. A process as claimed in claim 1, characterized in that said ink jet recording head accommodates ink to be ejected from said orifices (1106).

Inventors: GOTO AKIRA, ICHIKAWA FUMIO, MAEOKA KUNIHIKO, MASUDA KAZUAKI, ORIKASA TSUYOSHI, SATO OSAMU, WATANABE TAKASHI, GOTO, AKIRA, ICHIKAWA, FUMIO, MAEOKA, KUNIHIKO, MASUDA, KAZUAKI, ORIKASA, TSUYOSHI, SATO, OSAMU, WATANABE, TAKASHI
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1992
Main classification: B41J2
IPC codes: B41J2