Patent Publication Number: US-7581821-B2

Title: Head substrate, printhead, head cartridge, and printing apparatus

Description:
This is a divisional application of application Ser. No. 11/564,684, filed Nov. 29, 2006, now allowed, which is a continuation application of International application Ser. No. PCT/JP2005/009899, filed on May 30, 2005. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a head substrate, printhead, head cartridge, and printing apparatus, and, more particularly, to, e.g., a head substrate having a fuse ROM for holding/reading information, a printhead or head cartridge using the head substrate, and a printing apparatus using the printhead or head cartridge. 
     BACKGROUND ART 
     There is a proposal to arrange a ROM (Read Only Memory) on a head substrate integrated on an inkjet printhead (to be referred to as a printhead hereinafter) included in a recent inkjet printing apparatus (to be referred to as a printing apparatus hereinafter) to freely read out or hold information (individual information) unique to the head, including the ID (Identify) code of the printhead itself and the driving characteristic of the ink discharge mechanism. 
     In an arrangement using a printhead detachable from a printing apparatus main body, this approach is especially effective in acquiring information unique to the printhead. Patent reference 1 discloses arranging an EEPROM (Electrically Erasable Programmable ROM) in a printhead. 
     In another known method, a resistance indicating information unique to a head is formed on the base substrate of a head substrate together with the layer films of, e.g., an ink discharge mechanism. This approach is effective when the amount of information to be held in the printhead is relatively small. This method also allows a printing apparatus to obtain information unique to the printhead by reading the value of the resistance formed on the base substrate. The printing apparatus is capable of optimum driving for ink discharge based on the information. 
     Patent reference 2 discloses forming, on a base substrate used for manufacturing a head substrate, a fuse serving as a ROM (to be referred to as a fuse ROM hereinafter) simultaneously together with the layer films of, e.g., an ink discharge mechanism. When the fuse ROM is selectively melted under the control of a simultaneously formed logic circuit, the fuse ROM can hold binary data based on the presence/absence of the fuse. 
     A printhead having the above-described head substrate can simplify the structure, improve the productivity, reduce the cost, and reduce the weight and size while holding the information unique to the head. 
     Patent reference 1: Japanese Patent Publication Laid-Open No. 3-126560 
     Patent reference 2: Japanese Patent Publication No. 3428683 
     DISCLOSURE OF INVENTION 
     Problems that the Invention is to Solve 
     However, the printhead capable of storing individual information as described above in the prior art has the following problems to solve. 
     If the amount of data to be stored is large, it is useful to use an arrangement including a ROM chip such as an EEPROM separately from a head substrate. However, this inevitably increases the cost. Especially, when the amount of data to be stored is not large, a product according to this arrangement is not competitive in price in view of recent cost reduction of printing apparatuses. The printhead is also disadvantageous with regard to increasing productivity and reducing size and weight. 
     If the amount of data to be stored is not large, it is also possible to arrange, as a fuse ROM which serves as means for storing information, a heat generating element serving as an electrothermal transducer or a POLY wiring used as the gate wiring of a logic circuit, and simultaneously, apply the conventional manufacturing process to the logic circuit without increasing the number of processes of forming the substrate. In this method, the cost of wafer manufacture before individual substrates are formed is the same as before. Hence, it is possible to arrange a fuse ROM on a head substrate while suppressing the cost. 
     However, to print a high-quality image, the density of circuits in the head substrate is already high, and melting the fuse ROM may damage their functions. For this reason, any other circuit cannot be formed, e.g., on, under, and near the fuse ROM. 
     To melt or read-access a plurality of fuse ROMs, means for selecting one of them is necessary. To select a fuse RON as one method, a wiring connected to a fuse ROM connects to the outside of the head substrate to select the fuse ROM from the outside. In this case, electrode pads equal in number to fuse ROMs are necessary on the head substrate to electrically connect them to external wirings. The amount of data to be stored in the fuse ROMs after manufacturing and assembling the printhead is several ten bits, although it is not a large amount. To ensure pads to input/output such information on the head substrate, a considerable space is necessary, resulting in a bulky head substrate. In addition, the number of wirings outside the head substrate also increases in correspondence with the number of pads. 
       FIG. 20  is a view showing the layout of a conventional head substrate. 
     As shown in  FIG. 20 , many conventional head substrates have a large ink supply port H 1102  to supply ink from the back surface side to the front surface side of the substrate. For this reason, it is necessary to lay out, on the head substrate, electrothermal transducers, driving elements H 1116  to drive electrothermal transducers H 1103 , and selection circuits (AND circuits) H 1112  to select the driving elements while avoiding the ink supply port. An optimum layout is required even in mounting the fuses and their associated circuits on the head substrate. 
     The present invention has been made to solve the above-described problems, and has as its object to provide a head substrate having a storage element such as a fuse ROM, a printhead using the head substrate, a head cartridge using the printhead, and a printing apparatus using the printhead or head cartridge without increasing the head substrate size. 
     Means of Solving the Problems 
     In order to achieve the above object, a head substrate according to the present invention has the following arrangement. 
     More specifically, a head substrate comprises: an ink supply port which has a long hole shape elongated in a first direction; a plurality of printing elements arrayed along the first direction on both sides of the ink supply port; a plurality of first driving elements, arrayed along the first direction at positions spaced apart further away from the ink supply port than the plurality of printing elements, for driving the plurality of printing elements; a plurality of fuse ROMs for storing information; a plurality of second driving elements for driving the plurality of fuse ROMs; and a shared signal line used for driving the plurality of first driving elements and the plurality of second driving elements, wherein the first driving elements and the second driving elements are arrayed on both sides of an extension of the ink supply port. 
     Note that the plurality of second driving elements are preferably arranged at both ends of each array of the plurality of first driving elements. 
     Further mote that the plurality of fuse ROMs are preferably arranged in any of the following regions: 
     (1) an intermediate region which is sandwiched between extensions of the first driving elements on both sides of the ink supply port; 
     (2) in addition to (1), a region which is defined between the plurality of second driving elements; and 
     (3) a region which is defined adjacent to arrays of the plurality of printing elements, and between the plurality of second driving elements opposing the ink supply port. 
     Note that it is preferable in (2) and (3) arrangements that an external terminal commonly connects to a plurality of fuses included in the plurality of fuse ROMs. 
     Preferably, the head substrate further comprises a plurality of selection circuits, which are arrayed along the first direction at positions spaced apart further away from the ink supply port than the plurality of first driving elements and the plurality of second driving elements, for selectively driving the plurality of first driving elements and the plurality of second driving elements. 
     In the above arrangement, it is preferable that the plurality of printing elements comprise electrothermal transducers, and printing is executed by energizing the electrothermal transducers to generate heat and discharging ink by using the generated heat. 
     The head substrate having the above arrangement might further comprise a plurality of sets of the ink supply port, the plurality of printing elements, the plurality of first driving elements, the plurality of fuse ROMs, the plurality of second driving elements, and the shared signal line in correspondence with the number of inks to be used for printing. 
     Note that the plurality of fuse ROMs store information unique to a head. 
     A ground wiring of the plurality of printing elements and a ground wiring of the plurality of fuse ROMs are preferably a shared wiring. 
     According to another aspect of the invention, there is provided a printhead comprising a head substrate having the above arrangement, and a member to form an ink channel provided on the substrate. 
     The member to form the ink channel is preferably comprised of a resin layer, and a plurality of fuse ROMs are preferably provided closer to a side of an end of the head substrate than a removed part of the resin layer. 
     According to still another aspect of invention, there is provided an ink cartridge having the printhead and an ink tank which stores ink to be supplied to the printhead. 
     According to yet another aspect of the invention, there is provided a printing apparatus which prints by using a printhead or head cartridge with the above arrangement. 
     Effects of the Invention 
     Hence, according to the present invention, the plurality of first driving elements to drive the plurality of printing elements and the plurality of second driving elements to drive the plurality of fuse ROMs are arranged at appropriate positions, and the common signal line is used to drive these elements. This allows to efficiently use the space on the head substrate and prevent any increase in the head substrate size. 
     The utilization efficiency of the space on the head substrate can increase by arranging the plurality of fuse ROMs as in, e.g., claims  3  to  5 . 
     Other features and advantages of the present invention will be apparent from the following descriptions taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is an explanatory view showing an example of a printing apparatus capable of including an inkjet printhead of the present invention; 
         FIG. 2  is a block diagram showing the arrangement of the control circuit of the printing apparatus; 
         FIG. 3  is a perspective view showing the structure of a printhead cartridge H 1000 ; 
         FIG. 4  is an exploded perspective view of the printhead cartridge H 1000 ; 
         FIG. 5  is a partially cutaway perspective view for explaining the structure of a printhead H 1100 ; 
         FIG. 6  is a perspective view showing the structure of a printhead cartridge H 1001 ; 
         FIG. 7  is an exploded perspective view of the printhead cartridge H 1001 ; 
         FIG. 8  is a partially cutaway perspective view for explaining the structure of a printhead H 1101 ; 
         FIG. 9  is an enlarged view of the external signal input terminal portion of an electric wiring tape H 1301  of the printhead cartridge H 1001 ; 
         FIG. 10  is an enlarged view of the external signal input terminal portion of an electric wiring tape H 1300  of the printhead cartridge H 1000 ; 
         FIG. 11  is a view showing the layout of a head substrate H 1110  according to the first embodiment; 
         FIG. 12  is a view showing the overall layout of driving elements to drive fuse ROMs and AND circuits to select the driving elements; 
         FIG. 13  is a view showing the overall layout of the head substrate; 
         FIG. 14  is a view showing one example of the layout of the head substrate H 1110 ; 
         FIG. 15  is a view showing another example of the layout of the head substrate H 1110 ; 
         FIG. 16  is a view showing still another example of the layout of the head substrate H 1110 ; 
         FIG. 17  is a view showing another layout of the driving elements to drive fuse ROMs and the selection circuits; 
         FIG. 18  is a view showing the layout of a head substrate H 1110  according to the second embodiment; 
         FIG. 19  is a view showing the layout of a head substrate H 1110  according to the third embodiment; and 
         FIG. 20  is a view showing the circuit layout in a head substrate. 
     
    
    
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
         H 1000 , H 1001  printhead cartridge 
         H 1100 , H 1101  printhead 
         H 1102  ink supply port 
         H 1103  electrothermal transducer 
         H 1104  electrode 
         H 1105  bump 
         H 1106  ink channel wall 
         H 1107  orifice 
         H 1108  orifice group 
         H 1110  head substrate 
         H 1111  resistance for readout 
         H 1116  driving element 
         H 1117  fuse 
         H 1200 , H 1201  ink supply port 
         H 1300 , H 1301  electric wiring tape 
         H 1302  external signal input terminal 
         H 1303  opening 
         H 1304  electrode terminal 
         H 1500 , H 1501  ink supply holding member 
         H 1560  attachment guide 
         H 1570 , H 1580 , H 1590  butt portion 
         H 1600 , H 1601 , H 1602 , H 1603  ink absorber 
         H 1700 , H 1701 , H 1702 , H 1703  filter 
         H 1800 , H 1801  seal member 
         H 1900  lid member 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 
     In this specification, the term “print” (also referred to as “printing”) not only includes the formation of significant information such as characters and graphics, but also broadly includes the formation of images, figures, patterns, and the like on a printing medium, or the processing of the medium, regardless of whether they are significant or insignificant and whether they are so visualized as to be visually perceivable by humans. 
     Also, the term “printing medium” not only includes a paper sheet used in common printing apparatuses, but also broadly includes materials, such as cloth, a plastic film, a metal plate, glass, ceramics, wood, and leather, capable of accepting ink. 
     Furthermore, the term “ink” (to be also referred to as a “liquid”) should be extensively interpreted similar to the definition of “print (printing)” described above. That is, “ink” includes a liquid which, when applied onto a printing medium, can form images, figures, patterns, and the like, can process the printing medium, and can process ink (e.g., can solidify or insolubilize a coloring agent contained in ink applied to the printing medium). 
     Furthermore, unless otherwise stated, the term “nozzle” generally means a set of a discharge orifice, a liquid channel connected to the orifice and an element to generate energy utilized for ink discharge. 
     A printhead substrate (head substrate) indicates not a simple base made of silicon semiconductor but a structure including elements and wirings. 
     “On a substrate” indicates not only the upper side of a head substrate but also the upper surface of the head substrate and the inside of the head substrate near the upper surface. In the present invention, a term “built-in” indicates not simply separately arranging individual elements on the upper surface of a base but also integrally forming and manufacturing individual elements on an element substrate by, e.g., semiconductor circuit manufacturing steps. 
     &lt;Basic Arrangement of Printing Apparatus (FIGS.  1  and  2 )&gt; 
       FIG. 1  is an explanatory view showing an example of a printing apparatus capable of including an inkjet printhead or inkjet printhead cartridge (to be referred to as a printhead or printhead cartridge hereinafter) of the present invention. 
     As shown in  FIG. 1 , the printing apparatus has a carriage  102  having printhead cartridges H 1000  and H 1001  (to be described below) positioned and exchangeably mounted. The carriage  102  has an electrical connection portion to transmit driving signals to discharge portions through external signal input terminals on the printhead cartridges H 1000  and H 1001 . 
     The carriage  102  is supported along a guide shaft  103  to be reciprocally movable. The guide shaft  103  runs in the main scanning direction in the apparatus main body. A carriage motor  104  drives the carriage  102  via a driving mechanism including a motor pulley  105 , driven pulley  106 , and timing belt  107  and controls the position and movement of the carriage  102 . The carriage  102  has a home position sensor  130 . The home position sensor  130  on the carriage  102  detects the home position when passing through the position of a shielding plate  136 . 
     A feed motor  135  rotates pickup rollers  131  through a gear to separately feed each printing medium  108  on an automatic sheet feeder (ASF)  132 . A conveyance roller  109  rotates to convey the printing medium  108  through a position (printing position) facing the orifice surfaces of the printhead cartridges H 1000  and H 1001 . This conveyance direction is called a sub-scanning direction. Driving by a conveyance motor  134  is transmitted to the conveyance roller  109  through a gear. When the printing medium  108  passes through a paper end sensor  133 , whether or not a paper sheet has been fed is determined, and the edge position in paper feeding is determined. The paper end sensor  133  is also used to determine the actual trailing edge position of the printing medium  108  and finally detect the current printing position from the actual trailing edge position. 
     A platen (not shown) supports the back surface of the printing medium  108  to form a flat print surface in the printing position. In this case, the printhead cartridges H 1000  and H 1001  mounted on the carriage  102  are held between two pairs of conveyance rollers to be parallel to the printing medium  108  while making the orifice surfaces projecting downward from the carriage  102 . 
     The printhead cartridges H 1000  and H 1001  are mounted on the carriage  102  while making the array direction of orifices of each discharge portion intersect the scanning direction (main scanning direction) of the carriage  102 . The printhead cartridges H 1000  and H 1001  discharge ink from the orifice arrays to print. 
     If a printhead cartridge having the same structure as that of the printhead cartridge H 1001  and including light magenta, light cyan, and black inks replaces the printhead cartridge H 1000 , the printing apparatus can also serve as a high-quality photo printer. 
     A control arrangement to execute print control of the above-described printing apparatus will be described next. 
       FIG. 2  is a block diagram showing the arrangement of the control circuit of the printing apparatus. 
     Referring to  FIG. 2 , reference numeral  1700  denotes an interface to input a printing signal;  1701 , an MPU;  1702 , a ROM that stores control programs to be executed by the MPU  1701 ; and  1703 , a DRAM that saves various kinds of data (e.g., the printing signal and printing data to be supplied to the printhead cartridges). A gate array (G.A.)  1704  controls supply of printing data to the printhead cartridges H 1000  and H 1001 . The gate array  1704  also controls data transfer between the interface  1700 , MPU  1701 , and RAM  1703 . 
     A motor driver  1706  drives the conveyance motor  134 . A motor driver  1707  drives the carriage motor  104 . 
     The operation of the control arrangement will be described. A printing signal that has entered the interface  1700  is converted into printing data between the gate array  1704  and the MPU  1701 . The motor drivers  1706  and  1707  are driven. The printhead cartridges H 1000  and H 1001  are driven in accordance with the printing data sent to the carriage  102  to print an image on the printing medium  108 . 
     To optimally drive the printing element portions of the printhead cartridges H 1000  and H 1001 , the driving method of each printing element is determined by referring to characteristic information held in the fuse ROMs of the head substrate (to be described later). 
     &lt;Structure of Printhead (FIGS.  3  to  8 )&gt; 
       FIG. 3  is a perspective view showing the structure of the printhead cartridge H 1000 .  FIG. 6  is a perspective view showing the structure of the printhead cartridge H 1001 . 
     As shown in  FIGS. 3 and 6 , a printhead cartridge mounted on the printing apparatus according to this embodiment is a cartridge integrated with an ink tank and includes the printhead cartridge H 1000  filled with black ink, as shown in FIGS.  3 - a  and  3 - b , and the printhead cartridge H 1001  filled with color inks (cyan ink, magenta ink, and yellow ink), as shown in FIGS.  6 - a  and  6 - b . The printhead cartridges H 1000  and H 1001  are fixedly supported on the carriage  102  of the printing apparatus by positioning means and an electrical contact and are also detachable from the carriage  102 . If the contained inks run out, the printhead cartridge can be exchanged. 
     The constituent elements of the printhead cartridges H 1000  and H 1001  will be described below in detail. 
     Each of the printhead cartridges H 1000  and H 1001  is a printhead having electrothermal transducers that generate thermal energy to cause film boiling in accordance with an electrical signal. The printhead cartridge has a so-called side-shooter printhead in which electrothermal transducers face ink orifices. 
     [Printhead Cartridge H 1000 ] 
       FIG. 4  is an exploded perspective view of the printhead cartridge H 1000 . The printhead cartridge H 1000  includes a printhead H 1100 , electric wiring tape H 1300 , ink supply holding member H 1500 , filter H 1700 , ink absorber H 1600 , lid member H 1900 , and seal member H 1800 . 
     Printhead H 1100   
       FIG. 5  is a partially cutaway perspective view for explaining the structure of the printhead H 1100 . The printhead H 1100  includes a head substrate H 1110  that is made of, e.g., a 0.5 to 1 mm thick Si substrate having an ink supply port H 1102  serving as a through hole to flow ink from the lower surface of the substrate. 
     On the head substrate H 1110 , electrothermal transducers H 1103  are arrayed along the ink supply port H 1102  on its both sides (in this embodiment, an array of electrothermal transducers is arranged on each side of the ink supply port). In addition, electric wirings (not shown) made of, e.g., aluminum (Al) to supply power to the electrothermal transducers H 1103  are arranged while being spaced apart from the ink supply port H 1102  by a predetermined distance. It is possible to form the electrothermal transducers H 1103  and electric wirings by using a conventional film formation technique. In this embodiment, the electrothermal transducers H 1103  of the arrays on both sides of the ink supply port have a staggered pattern. That is, the positions of orifices H 1107  of the two arrays slightly shift without being located on one line in a direction perpendicular to the arrays. 
     It goes without saying that the present invention incorporates any structure except the staggered pattern. 
     Electrodes H 1104  to supply, to the electric wirings, power or an electrical signal to drive the electrothermal transducers H 1103  are arranged on the head substrate H 1110  while being arrayed along the sides located at the two ends of each array of the electrothermal transducers H 1103 . Each electrode H 1104  may have a bump H 1105  made of, e.g., Au. 
     On the surface of the head substrate H 1110  having a pattern of storage elements including the wirings and electrothermal transducers H 1103 , a structure made of resin material is formed by photolithography to form ink channels corresponding to the electrothermal transducers H 1103 . This structure has an ink channel wall H 1106  to partition the ink channels and a ceiling portion to cover the upper part of the ink channel wall H 1106 . The orifices H 1107  are open to the ceiling portion. The orifices H 1107  correspond to the electrothermal transducers H 1103 , respectively, to form an orifice group H 1108 . 
     In the printhead H 1100  having the above-described structure, ink supplied from the ink supply port H 1102  is discharged from the orifices H 1107  facing the electrothermal transducers H 1103  by the pressure of bubbles created by the heat from the electrothermal transducers H 1103 . 
     Electric Wiring Tape H 1300   
     The electric wiring tape H 1300  forms an electrical signal path to apply an electrical signal to the printhead H 1100  to discharge ink. The electric wiring tape H 1300  has an opening H 1303  to set the printhead H 1100  in it. The electric wiring tape H 1300  also has external signal input terminals H 1302  to receive an electrical signal from the printing apparatus. The external signal input terminals H 1302  and electrode terminals H 1304  are coupled by an interconnection pattern of a continuous copper foil. 
     For example, when the bumps H 1105  formed on the electrodes H 1104  of the printhead H 1100  join to the electrode terminals H 1304  of the electric wiring tape H 1300  corresponding to the electrodes H 1104  of the printhead H 1100 , electrical connection between the electric wiring tape H 1300  and the printhead H 1100  is ensured. 
     Ink Supply Holding Member H 1500   
     As shown in  FIG. 4 , the ink supply holding member H 1500  implements the function of an ink tank by having the absorber H 1600  to hold ink inside and generate negative pressure and the ink supply function by forming an ink channel to guide the ink to the printhead H 1100 . 
     The ink supply holding member H 1500  has an ink supply port H 1200  to supply black ink to the printhead H 1100 . The printhead H 1100  is accurately bonded to the ink supply holding member H 1500  to make the ink supply port H 1102  ( FIG. 5 ) of the printhead H 1100  communicate with the ink supply port H 1200  of the ink supply holding member H 1500 . 
     Lid Member H 1900   
     The lid member H 1900  has a fine port H 1910  to let a pressure variation in the ink supply holding member H 1500  relax and a fine groove H 1920  communicating with the fine port H 1910 . The seal member H 1800  covers most part of the fine port H 1910  and fine groove H 1920  while keeping one end of the fine groove H 1920  open, thereby forming an air communicating port H 1925  ( FIG. 3 ). The lid member H 1900  has an engaging portion H 1930  to fix the printhead cartridge H 1000  to the printing apparatus. 
     [Printhead Cartridge H 1001 ] 
       FIG. 7  is an exploded perspective view of the printhead cartridge H 1001 . The printhead cartridge H 1001  discharges inks of three colors, i.e., cyan, magenta, and yellow. As shown in  FIG. 7 , the printhead cartridge H 1001  includes a printhead H 1101 , electric wiring tape H 1301 , ink supply holding member H 1501 , filters H 1701  to H 1703 , ink absorbers H 1601  to H 1603 , lid member H 1901 , and seal member H 1801 . 
     Printhead H 1101   
       FIG. 8  is a partially cutaway perspective view for explaining the structure of the printhead H 1111 . The printhead H 1101  significantly differs from the printhead H 1100  in that three ink supply ports H 1102  for cyan, magenta, and yellow are juxtaposed. Arrays of the electrothermal transducers H 1103  and orifices H 1107  are arranged in a staggered pattern on both sides of each ink supply port H 1102 , A head substrate H 1110   a  has electric wirings, fuse ROMs, resistances, and electrodes, like the head substrate H 1110  of the printhead H 1100 . The ink channel wall H 1106  made of resin material and the orifices H 1107  are formed on the head substrate H 1110   a  by photolithography. Each electrode H 1104  to supply power to the electric wirings has the bump H 1105  made of, e.g., Au. 
     Electric Wiring Tape H 1301   
     The electric wiring tape H 1301  basically has the same structure as the electric wiring tape H 1300 , and a description thereof will be omitted. 
     Ink Supply Holding Member H 1501   
     The ink supply holding member H 1501  basically has the same structure and function as the ink supply holding member H 1500 , and a description thereof will be omitted. The ink supply holding member H 1501  has three independent spaces to hold three color inks. The spaces store the ink absorbers H 1601  to H 1603 . The three ink supply ports H 1201  provided on the bottom of the ink supply holding member H 1501  communicate with the ink supply ports H 1102  (see  FIG. 8 ) after assembly. 
     Lid Member H 1901   
     The lid member H 1901  has the same structure as the lid member H 1900 . The lid member H 1901  has fine ports H 1911  to H 1913  to let a pressure variation in the spaces of ink supply holding member H 1501  relax and fine grooves H 1921  to H 1923  communicating with the fine ports H 1911  to H 1913 . 
     Attachment of the above-described printheads to the inkjet printing apparatus will be described next in detail. 
     As shown in  FIGS. 3 and 6 , each of the printhead cartridges H 1000  and H 1001  has an attachment guide H 1560  to guide the printhead cartridge to the attachment position of the carriage  102  of the printing apparatus, the engaging portion H 1930  to attach and fix the printhead cartridge to the carriage by a head set lever, and an X-direction (main scanning direction) butt portion H 1570 , Y-direction (sub-scanning direction) butt portion H 1580 , and Z-direction (ink discharge direction) butt portion H 1590  to position the printhead cartridge to a predetermined attachment position of the carriage. These butt portions position the printhead cartridge to ensure accurate electrical contact between the external signal input terminals H 1302  on the electric wiring tapes H 1300  and H 1301  and the contact pins of the electrical connection portions provided in the carriage. 
     &lt;Structure of Contact Pads (FIGS.  9  and  10 )&gt; 
     Printhead Cartridge H 1001   
       FIG. 9  is an enlarged view of the external signal input terminal portion of the electric wiring tape H 1301  of the printhead cartridge H 1001 . Referring to  FIG. 9 , the electric wiring tape H 1301  has 32 external signal input terminals H 1302 . The external signal input terminals H 1302  include six ID contact pads H 1302   a  which are located almost at the center of the area where the external signal input terminals H 1302  are provided. The ID contact pads H 1302   a  connect to some of the electrodes H 1104  that exist at the two ends of each of the three ink supply ports H 1102  of the printhead H 1101  shown in  FIG. 8 . 
     Six VH contact pads H 1302   c  are arranged adjacent to one side (upper side in  FIG. 9 ) of the array of the ID contact pads H 1302   a  while being arrayed along them. The VH contact pads H 1302   c  connect to some of the electrode pads H 1104  at the two ends of the printhead H 1101  shown in  FIG. 8 . 
     Six GNDH contact pads H 1302   d  are arranged adjacent to the other side (lower side in  FIG. 9 ) of the array of the ID contact pads H 1302   a  while being arrayed along them. The GNDH contact pads H 1302   d  connect to some of the electrode pads H 1104  at the two ends of the printhead H 1101  shown in  FIG. 8 . 
     The remaining external signal input terminals H 1302  except the ID contact pads H 1302   a , VH contact pads H 1302   c , and GNDH contact pads H 1302   d  are used to supply power for transistors and other signals such as a control signal. 
     In the printhead cartridge H 1001 , the ID contact pads H 1302   a  relatively sensitive to static electricity are located almost at the center of the external signal input terminals H 1302 . With this layout, the user who is holding the printhead cartridge H 1001  hardly touches the ID contact pads H 1302   a . The user basically holds a printhead while taking precaution not to touch the external signal input terminals H 1302 . Hence, it is difficult to touch the pads located at the center. 
     Additionally, the ID contact pads H 1302   a  are adjacent to the VH contact pads H 1302   c  and GNDH contact pads H 1302   d  and are sandwiched between them. If a user puts his/her charged finger nearby the ID contact pads H 1302   a  and causes discharge, the discharge readily occurs in the VH contact pads H 1302   c  and GNDH contact pads H 1302   d . This structure can therefore almost prevent head specific information from being destroyed or accidentally rewritten by the discharge. 
     Printhead Cartridge H 1000   
       FIG. 10  is an enlarged view of the external signal input terminal portion of the electric wiring tape H 1300  of the printhead cartridge H 1000 . Referring to  FIG. 10 , the electric wiring tape H 1300  has 21 external signal input terminals H 1302 . Since the printhead cartridge H 1000  is a black ink cartridge, the number of terminals for power supply and control signal is smaller than in the above-described printhead cartridge H 1001  for inks of three colors, i.e., cyan, magenta, and yellow. The carriage  102  of the printing apparatus main body is designed such that a photo printhead having the same form as the printhead cartridge H 1001  is attachable in place of the printhead cartridge H 1000 . For this reason, the positions of the 21 external signal input terminals H 1302  of the printhead cartridge H 1000  correspond to the positions of the external signal input terminals H 1302  of the printhead cartridge H 1001 . 
     The external signal input terminals H 1302  provided on the electric wiring tape H 1300  include six ID contact pads H 1302   a  which are located almost at the center of the area where the external signal input terminals H 1302  are provided. The ID contact pads H 1302   a  connect to some of the electrode pads H 1104  that exist at the two ends of the ink supply port H 1102  of the head substrate H 1100  shown in  FIG. 5 . 
     Four VH contact pads H 1302   c  are arranged adjacent to one side (upper side in  FIG. 10 ) of the array of the ID contact pads H 1302   a  while being arrayed along them. The VH contact pads H 1302   c  connect to some of the electrode pads H 1104  at the two ends of the head substrate H 1100  shown in  FIG. 5 . 
     Four GNDH contact pads H 1302   d  are arranged adjacent to the other side (lower side in  FIG. 10 ) of the array of the ID contact pads H 1302   a  while being arrayed along them. The GNDH contact pads H 1302   d  connect to some of the electrode pads H 1104  at the two ends of the head substrate H 1100  shown in  FIG. 5 . 
     The remaining external signal input terminals H 1302  except the ID contact pads H 1302   a , VH contact pads H 1302   c , and GNDH contact pads H 1302   d  are used to supply power for transistors and other signals such as a control signal. 
     Even in the printhead cartridge H 1000 , the ID contact pads H 1302   a  relatively sensitive to static electricity are located almost at the center of the external signal input terminals H 1302 , like the printhead cartridge H 1001 . With this layout, the user who is holding the printhead cartridge H 1000  hardly touches the ID contact pads H 1302   a.    
     Additionally, the ID contact pads H 1302   a  are adjacent to the VH contact pads H 1302   c  and GNDH contact pads H 1302   d  and are sandwiched between them. If a user puts his/her charged finger nearby the ID contact pads H 1302   a  and causes discharge, this structure can almost prevent head specific information from being destroyed or accidentally rewritten by the discharge. 
     Several embodiments of the structure of the head substrate applied to the printing apparatus and printhead having the above-described arrangements will be described next. 
     First Embodiment 
       FIG. 11  is a view showing the layout of a head substrate according to the first embodiment. A printhead H 1100  has a head substrate H 1110  having semiconductor elements and wirings formed, by a semiconductor process, on a base made of silicon (Si). 
     As shown in  FIG. 11 , the head substrate H 1110  has fuse ROMs to store information (e.g., the head type, ink discharge characteristic, head individual identification information, use state, and ink consumption) unique to the head and necessary peripheral circuits.  FIG. 11  shows part of the head substrate. 
     Referring to  FIG. 11 , a long ink supply port H 1102  is formed in the silicon base. The long ink supply port can be of a rectangular, oblong, or elliptic shape. The ink supply port need only be an elongated opening capable of supplying ink in the longitudinal direction of the substrate. 
     Electrothermal transducers H 1103  such as resistors that form printing elements are arrayed on both sides of the ink supply port. In  FIG. 11 , the electrothermal transducers H 1103  on both sides of the ink supply port are arranged in a staggered pattern. However, they may be located without shift or need not always be arranged linearly. 
     Driving elements H 1116  to drive the electrothermal transducers H 1103  are arrayed at positions spaced apart further away from the ink supply port than the electrothermal transducers. Signal lines that supply signals to selectively drive the electrothermal transducers are arranged closer to the side of an end (an end of the long side of the substrate) of the substrate than the arrangement region of the driving elements H 1116 . 
     Reference numeral H 1117  denotes a fuse ROM. In this example, four fuse ROMs H 1117  each including a polysilicon resistor are arranged in the space on the extension of the ink supply port H 1102 . It is difficult to provide the circuits and wirings to drive the electrothermal transducers in the area near the ink supply port on its extension because of avoiding the ink supply port. This region having neither circuits nor wirings is usable to arrange the fuses close to each other while achieving space-saving. 
     In this embodiment, the fuse includes a polysilicon resistor. Instead, the fuse may include a metal film such as Al or a resistor made of the same material as that of the resistor of the printing element. This structure is more desirable because the fuses and electrothermal transducers can be formed in the same film formation step. 
     Each fuse ROM H 1117  connects to a driving element H 1118  to melt the fuse and read out information from it. The driving elements H 1118  are arranged on both sides of the extension of the ink supply port at positions adjacent to the other driving elements H 1116  for driving the electrothermal transducers H 1103 . 
     In this embodiment, signal lines to supply signals to select the driving elements H 1116  to drive the electrothermal transducers H 1103  are used as signal lines to supply signals to select the driving elements H 1118  to drive the fuse ROMs H 1117 . In this embodiment, the block enable signal lines to select the electrothermal transducers are shared to select fuses to be melted or accessed to read out information. 
     In order for the signal lines elongated along the long side end of the substrate to be shared, the driving elements H 1118  to drive the fuses have the same structure as the driving elements H 1116  to drive the electrothermal transducers and exist on the same arrays. The fuse ROMs H 1117  arranged on both sides of the extension of the ink supply port to be driven by the driving elements H 1118  are arranged in the intermediate region sandwiched between the extensions of the array directions of the driving elements H 1118 . This enables to obtain the ID terminal commonly connected to the fuses included in the fuse ROMs from a short side of the head substrate. Hence, the driving elements, fuse ROMs, and ID wirings can be arranged efficiently. 
     In this embodiment, a portion from a signal line (no electrode pad is illustrated) to receive a signal from the outside of the head substrate to a signal line connected to the driving element H 1118  through a shift register (S/R) H 1201 , latch circuit (LT) H 1202 , and decoder (DECODER) H 1203  shares the circuit to select the driving element H 1116 . A selection circuit (AND circuit) H 1112  for finally selecting the driving element H 1118  on the basis of the output from the shift register has the same structure as the selection circuit (AND circuit) for the driving element H 1116 . 
     Each VH pad  1104   c  to supply VH power connects to the electrothermal transducers H 1103  through a VH wiring H 1114 . Each GNDH pad H 1104   d  to supply GNDH power commonly connects to the driving elements H 1116  connected to the electrothermal transducers H 1103  and the driving elements H 1118  connected to the fuse ROMs H 1117  through a GNDH wiring H 1113 . That is, the driving elements H 1116  and H 1118  share the GNDH wirings H 1113 . 
     As described above, in this embodiment, a circuit having the same arrangement as the circuit for selecting the driving element H 1116  so as to select electrothermal transducer H 1103 , including a signal line to transfer a selection signal of the driving element H 1116 , the decoder (DECODER) H 1203  for generating a time-division selection signal (BLE), the latch circuit (LT) H 1202  and shift register (SIR) H 1201  including the other signals, and a signal input pad (not shown) from the outside of the head substrate, is used for selecting a fuse ROM. This makes it possible to select the driving element H 1118  to drive the fuse ROM H 1117  without adding any new signal line, wiring region, and circuit. 
     An ID pad H 1104   a  functions as a fuse melting power supply terminal to apply a voltage in melting the fuse ROM H 1117  and as a signal output terminal in reading out information from the fuse ROM. More specifically, to melt the fuse ROM H 1117 , a voltage (e.g., the driving voltage (24 V) of the electrothermal transducer) is applied to the ID pad H 1104   a  to drive the driving element H 1118  selected by the selection circuit and instantaneously melt the corresponding fuse ROM H 1117 . At this time, an ID power supply pad H 1104   b  serving as a fuse read power supply terminal is kept open. On the other hand, to read out information, a voltage (e.g., the power supply voltage (3.3 V) of the logic circuit) is applied to the ID power supply pad H 1104   b . If the fuse ROM H 1117  is open, a high-level (H) signal is output to the ID pad H 1104   a . If the fuse ROM H 1117  is not open, a low-level (L) signal is output to the ID pad H 1104   a  because of a read resistance H 1111  significantly larger than the resistance value of the fuse ROM H 1117 . 
     As is apparent from the above description, a fuse ROM is designed to be melt upon receiving a voltage (e.g., 24 V) to drive the electrothermal transducers. Hence, the conventional power supply arrangement is usable to melt the fuse ROM without adding any new power supply on the printing apparatus side. Similarly, use of the power supply voltage of the logic circuit allows to design the fuse ROM H 1117  that does not give any damage on elements on the head substrate upon reading, without adding any new power supply on the printing apparatus side. The printing apparatus side can receive a signal from the fuse ROM H 1117  by using an existing circuit. 
       FIG. 12  is a view showing the overall layout of the driving elements to drive the fuse ROMs and the AND circuits to select the driving elements. 
     As shown in  FIG. 12 , the driving elements H 1118  are arranged adjacent on both sides of the driving elements H 1116  which are arrayed in the substrate longitudinal direction (longitudinal direction) on both sides of the ink supply port H 1102  and its extension. The AND circuit H 1112  is arranged on the rear side of each driving element H 1118 . 
     On the basis of the layout arrangement of the driving elements and selection circuits of the fuse ROMs shown in  FIG. 12 , the logic circuits such as the shift registers (S/R) H 1201 , latch circuits (LT) H 1202 , and decoders (DECODER) H 1203  can have various layouts. 
       FIG. 13  is a view showing the overall layout of the head substrate. The same reference numerals as described above denote the same constituent elements in  FIG. 13 . 
     As shown in  FIG. 13 , the shift registers (S/R) H 1201  and latch circuits (LT) H 1202  may be arranged on one side of the printhead H 1100  in the longitudinal direction while the decoders (DECODER) H 1203  may be arranged on the other side. Power supply circuits (Tr power supplies) H 1204  to supply power to the driving elements H 1116  and H 1118  are arranged on the same side as the decoders (DECODER) H 1203 . 
     Referring to  FIG. 13 , the GNDH wirings H 1113  and VH wirings H 1114  are illustrated as wiring regions, unlike  FIG. 11 . The fuse ROMs H 1117  are collectively represented by “FUSE”. The electrode pad layout is different from  FIG. 11  because it reflects the embodiment. Reference numeral H 1104   g  denotes a data signal (DATA)/block selection signals (B 0  to B 3 ) input pad. An input pad H 11041  supplies power to the power supply circuits (Tr power supplies) H 1204 . Alignment marks H 1205  are used upon assembling the printhead. The fuse ROMs and electrothermal transducers share the GNDH wirings H 1113 . 
     According to the above-described embodiment, the logic circuit arrangement is partially shared to write/read information in/from a fuse ROM. The fuse ROMs are arranged by using the space between the logic circuits. Hence, a head substrate having a fuse ROM serving as a storage element can be provided without increasing the head substrate size. 
     The driving elements H 1118  are arranged adjacent to the driving elements H 1116  which are arrayed on both sides of the ink supply port H 1102  and its extension. This allows the elements for selectively driving the fuse ROMs to be well-balanced distributed in the head substrate regardless of the number of bits of fuse ROMs and the number of ink supply ports, resulting in suppressing any increase in the head substrate size. 
     The fuse ROMs are arranged in the intermediate region sandwiched between the extensions of the arrays of the driving elements. Hence, the fuses can be arranged while avoiding the VH wirings and GND wirings. 
     When the fuse ROMs are arranged in the intermediate region between the logic circuits such as shift registers and the ink supply port (example in  FIG. 13 ), a free space where there are no wirings and circuits on and under the fuse ROMs can effectively be used. Hence, the circuit layout efficiency on the head substrate becomes high. 
     The layout relationship between the ink supply port, the circuits including fuses, and the wirings on the head substrate has been described above. The following points are preferably taken into consideration even for the relationship with the members included in the liquid channel wall of the printhead. 
     A resin layer to form the ink channel is formed on the head substrate. If the fuses are arranged near the ink supply port, as described above, ink that has permeated between the substrate surface and the resin layer may corrode the fuses. To prevent this, the resin layer that forms the channel is partially removed, as indicated by H 1117   b  in  FIG. 5 . The fuses are arranged at positions (on the side close to an end of the substrate) spaced apart further away from the ink supply port than the removed part. This allows to maintain the layout arrangement and increase the reliability of the fuses. 
     A printhead H 1101  used in a printhead cartridge H 1001  for color printing basically has the same structure as described above. However, the logic circuits such as the shift registers (S/R) H 1201 , latch circuits (LT) H 1202 , and decoders (DECODER) H 1203  and the input pads around the head substrate can have various layouts. 
     Some layouts applicable to the head substrate for color printing will be described below. 
     FIRST EXAMPLE 
       FIG. 14  is a view showing an example of the layout of the head substrate H 1110 . 
     As shown in  FIG. 14 , the head substrate H 1110  has three ink supply ports H 1102  corresponding to three color inks. Identical circuit arrangements are arranged around the ink supply ports. 
     In this example, the shift registers (S/R) H 1201  and latch circuits (LT) H 1202  to supply a printing signal and control signal to the driving elements and selection circuits arranged on both sides of each ink supply port H 1102  are arranged in the region between the fuse ROMs (FUSE) and the input pad group on the upper side of the head substrate. On the other hand, the decoders (DECODER) H 1203  and power supply circuits (Tr power supplies) H 1204  to supply a time-division selection signal and driving power to the driving elements and selection circuits arranged on both sides of each ink supply port H 1102  are arranged in the region between the fuse ROMs (FUSE) and the input pad group on the lower side of the head substrate. 
     SECOND EXAMPLE 
       FIG. 15  is a view showing another example of the layout of the head substrate H 1110 . 
     As shown in  FIG. 15 , the head substrate H 1110  has three ink supply ports H 1102  corresponding to three color inks. Identical circuit arrangements are arranged around the ink supply ports. 
     In this example, the shift register (S/R) H 1201 , latch circuit (LT) H 1202 , and decoder (DECODER) H 1203  to supply a printing signal, control signal, time-division selection signal, and driving power to the driving elements and selection circuits arranged on the left side of each ink supply port H 1102  are arranged in the region between the fuse ROMs (FUSE) and the input pad group on the upper side of the head substrate. On the other hand, the shift register (S/R) H 1201 , latch circuit (LT) H 1202 , decoder (DECODER) H 1203 , and power supply circuit (Tr power supply) H 1204  to supply a printing signal, control signal, time-division selection signal, and driving power to the driving elements and selection circuits arranged on the right side of each ink supply port H 1102  are arranged in the region between the fuse ROMs (FUSE) and the input pad group on the lower side of the head substrate. 
     The power supply circuit (Tr power supply) to drive elements on the left side of each ink supply port H 1102  is arranged at the lower left on the drawing. The power supply circuit (Tr power supply) to drive elements on the right side is arranged at the upper right on the drawing. 
     THIRD EXAMPLE 
       FIG. 16  is a view showing still another example of the layout of the head substrate H 1110 . 
     As shown in  FIG. 16 , the head substrate H 1110  has three ink supply ports H 1102  corresponding to three color inks. Identical circuit arrangements are arranged around the ink supply ports. 
     In this example, the shift register (S/R) H 1201 , latch circuit (LT) H 1202 , and power supply circuit (Tr power supply) H 1204  to supply a printing signal, control signal, and driving power to the upper half of the driving elements and selection circuits arranged on both sides of each ink supply port H 1102  are arranged in the region between the fuse ROMs (FUSE) and the input pad group on the upper side of the head substrate. On the other hand, the shift register (S/R) H 1201 , latch circuit (LT) H 1202 , and power supply circuit (Tr power supply) H 1204  to supply a printing signal, control signal, and driving power to the lower half of the driving elements and selection circuits arranged on both sides of each ink supply port H 1102  are arranged in the region between the fuse ROMs (FUSE) and the input pad group on the lower side of the head substrate. The half portion need not be just ½ the substrate in the longitudinal direction. 
     The decoders (DECODER) H 1203  to supply a time-division selection signal to the driving elements and selection circuits arranged on both sides of each ink supply port H 1102  are arranged in the region between the fuse ROMs (FUSE) and the input pad group on the upper side of the head substrate. 
     As is apparent from  FIG. 16 , the four shift registers (S/R) H 1201  and four latch circuits (LT) H 1202  arranged around each ink supply port H 1102  are responsible for supplying a printing signal and control signal to the driving elements and selection circuits arranged at the upper left portion, lower left portion, upper right portion, and lower right portion of the ink supply port H 1102 , respectively. 
     In the above-described examples, the driving elements H 1118  are arranged adjacent on both sides of each of the arrays of the driving elements H 1116  on both sides of the ink supply port H 1102 . The AND circuit H 1112  is arranged on the rear side of each driving element H 1118 . However, the present invention is not limited to this. For example, if the information storage amount required of the fuse ROM is small, it is unnecessary to arrange the fuse ROMs shown in  FIGS. 13 to 16  on both sides of the head substrate. Instead, they may be arranged on one side of the head substrate. In this case, for example, the driving elements H 1118  may be arranged on only one side of each of the arrays of the driving elements H 1116  on both sides of the ink supply port H 1102 , as shown in  FIG. 17 . Even this layout allows the elements for selectively driving the fuse ROMs to be well-balanced distributed. This results in efficiently utilizing the space on the head substrate. 
     Second Embodiment 
     All the examples described in the first embodiment employ an arrangement with the fuse ROMs laid out on the extension of the rectangular ink supply port in the longitudinal direction. An arrangement with fuse ROMs laid out between an ink supply port and driving elements, like electrothermal transducers H 1103 , will be described here. Even in this embodiment, the fuses are arranged in the intermediate region sandwiched between the extensions of the driving elements arranged on both sides of the ink supply port. 
       FIG. 18  is a view showing the layout of a head substrate according to the second embodiment. A printhead H 1100  has semiconductor elements and wirings formed on a head substrate H 1110  by a semiconductor process. 
     In the second embodiment, the head substrate H 1110  has fuse ROMs to store information unique to the head and necessary peripheral circuits, as in the first embodiment.  FIG. 18  shows part of the head substrate. The same reference numerals as described above denote the same constituent elements in  FIG. 18 , and a description thereof will be omitted. 
     As shown in  FIG. 18 , fuse ROMs H 1117  are arranged between an ink supply port H 1102  and driving elements H 1118  for driving the fuse ROMs, like the electrothermal transducers H 1103 . In this case, considering the safety in melting a fuse ROM, the interval between the fuse ROM H 1117  and the electrothermal transducer H 1103  is equal to or greater than that between the electrothermal transducers H 1103 . 
     According to the above-described embodiment, the fuse ROMs are arranged in a space between the ink supply port and the driving elements, compared to the arrangement described in the first embodiment with reference to  FIG. 11 . Hence, it is possible to more efficiently use the space on the head substrate. 
     Third Embodiment 
     The examples described in the first and second embodiments have the logic circuits such as a shift register, latch circuit, and decoder mounted on the head substrate. An arrangement with logic circuits outside a head substrate will be described here. 
     Although shift registers, latch circuits, and decoders are present outside the head substrate, they still share signal lines for selecting driving elements to drive heating elements and driving elements to drive the fuses. 
       FIG. 19  is a view showing the layout of a head substrate according to the third embodiment. A printhead H 1100  has semiconductor elements and wirings formed on a head substrate H 1110  by a semiconductor process. 
     In the third embodiment, the head substrate H 1110  has fuse ROMs to store information unique to the head, as in the first and second embodiments.  FIG. 19  shows part of the head substrate. The same reference numerals as described above denote the same constituent elements in  FIG. 19 , and a description thereof will be omitted. 
     As shown in  FIG. 19 , driving elements H 1118  are arranged adjacent at one end of driving elements H 1116  which are arrayed on both sides of an ink supply port H 1102 . An AND circuit H 1112  is arranged on the rear side of each driving element H 1118 . This allows the arrangement up to the selection circuit (AND circuit) H 1112  for inputting a selection signal to the driving element H 1118  to be laid out in the same manner as the driving elements H 1116 . This results in avoiding influence on the layout of the opening of the ink supply port H 1102  and signal lines. 
     The driving elements H 1116  for driving electrothermal transducers H 1103  and the driving elements H 1118  for driving the fuse ROMs H 1117  share GNDH wirings H 1113 , as described in the first embodiment. This arrangement results in eliminating the necessity of collective arrangement of the circuits for selectively driving the fuse ROMs H 1117 , and it contributes to effective utilization of the space on the head substrate. 
     In the layout according to this embodiment, the fuse ROMs are arranged in a region H 1120  surrounded by a broken line. As shown in  FIG. 19 , the region H 1120  is defined as not only a region that exists on the extension of the rectangular ink supply port H 1102  in the longitudinal direction but also a region that is sandwiched between the opposing driving elements H 1118  arranged adjacent at the ends of the arrays of the driving elements H 1116  on both sides of the ink supply port H 1102 . 
     Since there are no power supply wirings of the electrothermal transducers H 1103  in the region H 1120 , the fuse ROMs H 1117  can advantageously be arranged without influencing the wirings. 
     This layout will be compared with a conventional art. 
     As described in the conventional art, the fuse ROMs H 1117  are melted. Hence, it is impossible to place any elements and wirings on or under the layout region of the fuse ROMs on the head substrate from the viewpoint of safety and reliability. Especially the fuse ROMs need be arranged while avoiding the power supply wirings to the electrothermal transducers H 1103 , which cover most part of the surface of the head substrate so as to accurately control the thermal energy to be generated and suppress excess heating. Additionally, the fuse ROMs need to be arranged while avoiding the ink orifices and the ink supply port passing through the head substrate from the back surface to the front surface to supply ink to the ink orifices. 
     To the contrary, the layout according to the third embodiment enables to lay out the fuse ROMs by efficiently using a region, near the ink supply port, where there are no power supply wirings of the electrothermal transducers H 1103 , and which is sandwiched between the opposing driving elements. Hence, the space on the head substrate can effectively be used without wasting the space. 
     A printhead H 1101  basically has the same structure as described above. 
     In the above-described embodiments, the droplet discharged from the printhead is an ink droplet, and the liquid stored in the ink tank is ink. However, the content is not limited to ink. The ink tank may store, e.g., process liquid that is discharged to the printing medium to increase the adhesion and water repellency of a printed image and/or increase the quality of the image. 
     The present invention is also effective for the above-described serial type printhead, a printhead fixed to the apparatus main body, or an exchangeable cartridge type printhead capable of ensuring electrical connection to the apparatus main body when attached to it and receiving ink from the apparatus main body. 
     The inkjet printing apparatus of the present invention can take any form such as an image output device for an information processing device such as a computer, a copying machine combined with a reader, or a facsimile apparatus having a transmitting/receiving function. 
     The present invention is not limited to the above embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, to apprise the public of the scope of the present invention, the following claims are made. 
     CLAIM OF PRIORITY 
     This application claims the benefit of Japanese Patent Application No. 2004-164555, filed Jun. 2, 2004 and Japanese Patent Application No. 2005-149620, filed May 23, 2005 which are hereby incorporated by reference herein in their entirety.