Patent Publication Number: US-9902163-B2

Title: Liquid ejecting head and liquid ejecting apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a liquid ejecting head and a liquid ejecting apparatus. 
     Description of the Related Art 
     There is known a method in which a liquid ejecting apparatus main body and a liquid ejecting head are electrically connected by contacting contact points provided in both. In the connection, in the case where a contact point of a signal system for control for controlling a liquid ejecting element provided in the liquid ejecting head is connected before a contact point of a ground system for control is connected, so-called latch-up may be generated. In Japanese Patent Laid-Open No. H09(1997)-174822, a configuration, in which contact timing of a signal system is made later than contact timing of a ground system, is disclosed. 
     Recently, the number of liquid ejecting elements that are provided in a liquid ejecting head tends to be increased for high-speed processing, or print of a high-resolution image. In a case where the number of liquid ejecting elements is increased, an amount of the current flowing through a wiring for driving to drive the liquid ejecting element is also increased. In a configuration in which the wiring and a wiring for controlling the liquid ejecting element are made to run in parallel, the increase in the amount of the current also causes the increase in the influence of noise on the control signal for the liquid ejecting element, and an intended liquid ejecting operation may not be executed by the influence of noise. 
     In Japanese Patent Laid-Open No. H09(1997)-174822, measures against the noise are not considered, and thus the influence of noise on control signals may not be suppressed. 
     SUMMARY OF THE INVENTION 
     The present invention has been achieved in consideration of the above-described problem, and an object thereof is to provide a liquid ejecting head and a liquid ejecting apparatus which can suppress the influence of noise on a control signal. 
     According to a first aspect of the present invention, there is provided a liquid ejecting head comprising: a plurality of terminals for being electrically connected with a contact point provided in a liquid ejecting apparatus; and a liquid ejecting element substrate having a liquid ejecting element formed for ejecting a liquid in response to a control signal transmitted from the liquid ejecting apparatus, wherein the plurality of terminals includes a signal terminal and a ground terminal for control, for controlling the liquid ejecting element; and the signal terminal and the ground terminal for control are arranged in positions closer to the liquid ejecting element substrate than other terminals included in the plurality of terminals. 
     According to a second aspect of the present invention, there is provided a liquid ejecting apparatus capable of mounting a liquid ejecting head, wherein: the liquid ejecting head has a plurality of terminals for being electrically connected with a contact point provided in a liquid ejecting apparatus; and a liquid ejecting element substrate having a liquid ejecting element formed for ejecting a liquid in response to a control signal transmitted from the liquid ejecting apparatus, the plurality of terminals includes a signal terminal and a ground terminal for control, for controlling the liquid ejecting element; and the signal terminal and the ground terminal for control are arranged in positions closer to the liquid ejecting element substrate than other terminals included in the plurality of terminals. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view showing an internal configuration of a liquid ejecting apparatus using a liquid ejecting head; 
         FIG. 2  is a perspective view showing the liquid ejecting head; 
         FIG. 3  is a circuit diagram showing a drive circuit of the liquid ejecting head; 
         FIGS. 4A and 4B  are schematic views each showing a contact substrate; 
         FIG. 5  is a schematic view showing a layout of terminals and wirings; 
         FIG. 6  is a schematic view for explaining the influence of noise; 
         FIGS. 7A and 7B  are drawings each showing a mounting method of the liquid ejecting head; and 
         FIGS. 8A to 8C  are schematic views each showing other examples of a layout of terminals. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to drawings. 
       FIG. 1  is a schematic perspective view showing an internal configuration of a liquid ejecting apparatus (hereinafter, referred to as a “print apparatus”)  10  using a liquid ejecting head (hereinafter, referred to as a “print head”)  1 . The print apparatus  10  is an ink-jet print apparatus of a serial scan system. In the print head  1 , an ejection port (not shown) is formed on a surface facing a sheet S. The liquid is given to the sheet S by ejecting a liquid from the ejection port downward in the z direction shown in the drawing. Note that, here, a case where ink is ejected from the ejection port will be explained. The print head  1  is mounted on a carriage  2 . The carriage  2  is reciprocatingly guided in the x direction by using guide shafts  3  and  4  extending in the main scanning direction (the x direction shown in the drawing). 
     The sheet S inverts, after being inserted into the print apparatus  10  from an insertion port  6  provided in the print apparatus  10 , the traveling direction thereof, and then, is conveyed in a sub-scanning direction (the y direction shown in the drawing) by a roller  5 . In the print apparatus  10 , an image is printed on the sheet S by repeating a print operation of ejecting ink from the print head  1  along with the movement of the carriage  2 , and a conveyance operation of the sheet S by the roller  5 . 
     Here, the print head  1  is assumed to utilize, as energy for ejecting ink, heat energy that is generated from an electrothermal converter (heater) being a print element. In this case, the ink is caused to generate film boiling by heat generation of the heater, and the ink is ejected from the ejection port by a foaming energy at that time. Note that a piezoelectric element or the like may be used as the print element. 
       FIG. 2  is a perspective view showing the print head  1 . As shown in the drawing, the print head  1  includes a housing  11 , a contact substrate  20 , a wiring member  15 , and a print element substrate unit  12 . The contact substrate  20 , the wiring member  15 , and the print element substrate unit  12  are fixed to the housing  11 . An ink tank (not shown) storing ink is mounted on the housing  11 , and a flow path for supplying ink to the print element substrate unit  12  from the ink tank is provided inside the housing  11 . 
     The print element substrate unit  12  includes a print element substrate (liquid ejecting element substrate)  13 . The print element substrate  13  is an Si substrate, and an opening serving as an ink flow path is formed on the print element substrate  13 , by anisotropic etching. Furthermore, the print element substrate  13  is provided with a plurality of heaters as a print element. The print element substrate  13  is provided with a plurality of ink flow paths and a plurality of ejection ports formed by photolithography using a resin material. The ink in the ink tank passes through the flow path and goes toward the ejection port, by communicating the flow path of the housing  11  and the flow path of the print element substrate  13 . Note that four openings each serving as the ink flow path are formed on one print element substrate  13 , and inks of different colors can be ejected from ejection port rows of four rows in one print element substrate  13 . 
     The print element substrate unit  12  has a support member  14  made from an alumina material, and the print element substrate  13  is supported by the support member  14 . Note that, in  FIG. 2 , there is shown the case where three print element substrates  13  are used, but the number of usable print element substrates is not limited to three. Furthermore, in  FIG. 2 , there is shown the case where ejection port rows of four rows are formed for one print element substrate  13 , but the row number of ejection port rows is also not limited to four. 
     The wiring member  15  electrically connects an electrode portion of the print element substrate  13  with a terminal in the contact substrate  20 . Signals from the print apparatus  10  are transmitted to the print element substrate  13  of the print element substrate unit  12  via the contact substrate  20  and the wiring member  15 . The wiring member  15  is provided with an opening portion in a position that corresponds to the position where the print element substrate  13  is arranged, and the opening shape of the opening portion is a rectangle. An electrode portion to be electrically connected with the electrode portion of the print element substrate  13  is provided near the short side of the opening portion. Furthermore, the wiring member  15  is provided with a connection portion for connecting electrically with the connection portion of the contact substrate  20 . Note that an electric wiring tape or the like can be used as the wiring member  15 . 
     Although details will be described later with reference to  FIG. 4  and the like, various types of terminals are provided on the contact substrate  20 . In addition, although description will be made later with reference to  FIGS. 7A and 7B , the carriage  2  is provided with an electric connection pin  30 , in a position that makes contact with the terminal of the contact substrate  20  in the case where the print head  1  is mounted. The electric connection pin  30  is electrically connected to a control circuit on the print apparatus  10  side. In the case where the terminal of the contact substrate  20  and the electric connection pin  30  are contact-connected to each other, the contact substrate  20  and a control circuit (not shown) on the print apparatus  10  side are electrically connected to each other, and electric power is supplied to the print element substrate  13  from the print apparatus  10  side via the contact substrate and signals are transmitted. Here, a low voltage differential signal transmission system (LVDS) is used as a transmission system of signals, but another transmission system may be used. Ejection of ink is controlled on the basis of the signal transmitted from the control circuit of the print apparatus  10 , and an image is printed on the sheet S. 
       FIG. 3  is a circuit diagram showing a drive circuit of the print head  1 . The print element substrate  13  is provided with a heater  50 , a drive element  51  and a drive signal generation circuit  52 . The drive signal generation circuit  52  has a shift register circuit (not shown), a latch circuit (not shown), a decode circuit (not shown) and the like, and generates drive signals for the drive element on the basis of the signal from a control circuit of the print apparatus  10 . In a case where the drive element  51  is turned ON according to the generated drive signal, a voltage is applied to the heater  50 . 
     As shown in  FIG. 3 , a VH wiring and a GNDH wiring are separately wired for every block in the print element substrate  13 , but each thereof is formed into one wiring in the contact substrate  20 . According to this wiring, an electric current flowing through the VH wiring and the GNDH wiring in the contact substrate  20  increases along with the increase in number of print elements. In this case, noise enters control signals (data signals) transmitted by the DATA wiring, and an intended print operation may not be executed. Accordingly, here, terminals are arranged so as to suppress the influence of noise on data signals. Details will be described later with reference to  FIGS. 5 and 6 . 
       FIGS. 4A and 4B  are schematic views showing a surface on which terminals of the contact substrate  20  are provided. As shown in  FIGS. 4A and 4B , the contact substrate  20  is provided with a plurality of terminals  21  to  23 , and has six rows of terminals that are constituted of a plurality of the terminals arranged along the x direction. The contact substrate  20  shown in  FIGS. 4A and 4B  is provided with one hundred and twenty-four terminals. The terminals include a print element (heater) power source terminal (VH)  23 , a heater ground terminal (GNDH)  22 , a data signal terminal (DATA)  21 , a logic power source terminal (VDD)  25 , and a ground terminal (VSS)  24 . The VH (power source terminal for drive)  23  is a drive power source of the heater. The GNDH (ground terminal for drive)  22  is a ground of the heater. The DATA (signal terminal)  21  is a terminal that transfers serial data for independently turning ON/OFF respective heaters. The VDD (power source terminal for control)  25  is a power source for a logic signal, and the VSS (ground terminal for control)  24  is a ground for a logic signal. Namely, the VH  23  and the GNDH  22  are terminals for driving elements to drive the heater, and the DATA  21 , the VDD  25  and the VSS  24  are terminals for controlling elements to control the heater. Here, a voltage of 32 V is assumed to be applied to the VH  23  and the GNDH  22 , and a voltage of 3.3 V is assumed to be applied to the VDD  25  and the VSS  24 . 
     As shown in  FIGS. 4A and 4B , terminal rows of two rows including a plurality of DATAs  21 , terminal rows of two rows including a plurality of GNDHs  22 , and terminal rows of two rows including a plurality of VHs  23  are arranged in this order of positions closer to the wiring member  15  (the print element substrate  13 ). Furthermore, as shown in  FIGS. 4A and 4B , in the terminal row at the lowermost part in the z direction among the terminal rows of the DATA  21 , the VSS  24  is arranged on both sides in the arrangement direction of the terminals (x direction). Moreover, in  FIG. 4B , the VDD  25  is arranged on both sides in the x direction of the terminal row of the second terminal row from the bottom in the z direction among the terminal rows of the DATA  21 . 
     Here, with reference to  FIG. 3  again, a flow of drive of the print element by signals that are input from a terminal will be explained. In the configuration shown in  FIG. 3 , there is used a time division drive system in which print elements are sequentially driven for each block while setting sixteen print elements as one block. CLK shown in  FIG. 3  is a terminal that transfers clock signals for synchronizing the transfer of serial data that is input to the DATA  21 . LAT is a terminal that transfers a latch signal serving as a trigger for shifting the serial data to a holding circuit in a print element substrate. BLK is a terminal that transfers a block selection signal for selecting a block to be driven. HEAT is a terminal that transfers a pulse signal for controlling VH application time with respect to a print element by pulse length. 
     The serial data that has been input via the DATA  21  are transferred to a shift register circuit (not shown) in the print element substrate  13  in synchronization with the clock signal. A data group input to the shift register circuit is held in a latch circuit (not shown) by the input of the latch signal, and a pulse-shaped drive signal is generated by subjecting the held data, the pulse signal and the block selection signal to AND processing. The drive element  51  is turned ON/OFF by the drive signal, and thus the drive of the heater  50  (print element) is turned ON/OFF. 
       FIG. 5  is a schematic view showing a layout of terminals and wirings. Note that it is not indispensable to provide terminals on the contact substrate  20  as shown in  FIGS. 2 and 4 , but terminals may be patterned on the wiring member  15 . In  FIG. 5 , the case where terminals and wirings are patterned on the wiring member  15  is shown. Also in  FIG. 5 , in the same way in  FIGS. 4A and 4B , the terminal row of the DATA  21 , the terminal row of the GNDH  22  and the terminal row of the VH  23  are arranged in order of positions closer to the print element substrate  13 . In this case, when a simple wiring configuration is to be adopted, the configuration shown in  FIG. 5  is given. Since the DATA  21  is arranged in a position closest to the print element substrate  13 , the length of the DATA wiring gives the shortest distance among possible configurations that may be considered, as shown in  FIG. 5 . 
       FIG. 6  is a schematic view for explaining the influence of noise. As shown in  FIG. 6 , in the VH wiring (power source wiring) and the GNDH wiring (ground wiring), flows of the signal are opposite to each other. Intensity of a magnetic field is proportional to the magnitude of an electric current and inversely proportional to distance. As shown in  FIG. 6 , when the VH wiring and the GNDH wiring are made to run in parallel to each other, magnetic fields generated from both are intensified in a region  26  being a region between the VH wiring and the GNDH wiring, and are weakened in a region  27  being a region not between the VH wiring and the GNDH wiring. Accordingly, in the case where a DATA wiring (signal wiring) is arranged between the VH wiring and the GNDH wiring, the influence of noise on data signals becomes large. In contrast, here, as shown in  FIG. 5 , the DATA  21  is arranged in a position that is closest to the print element substrate  13 , and thus the VH wiring and the GNDH wiring are made to run in parallel without arranging a DATA wiring between the VH wiring and the GNDH wiring. Therefore, in the present embodiment, the influence of noise on data signals can be suppressed. 
     In this way, here, the DATA  21  is arranged in a position closer to the print element substrate  13  than other terminals, and thus the DATA wiring is comparatively shortened and the distance of running parallel to another wiring is shortened. In this case, it is possible to make the VH wiring and the GNDH wiring run parallel to each other and to arrange the DATA wiring outside the region between the VH wiring and the GNDH wiring. Accordingly, the influence of noise on data signals can be suppressed, and a transmission performance of data signals from the print apparatus  10  side to the print element substrate  13  can be ensured. Note that, as shown in  FIG. 5 , in the case where the GNDH  22  and the VH  23  are arranged adjacent to each other, the VH wiring and the GNDH wiring can be arranged in parallel without adopting a complicated configuration. 
       FIGS. 7A and 7B  are drawings for explaining a mounting method of the print head  1  onto the carriage  2 .  FIG. 7A  shows the case where a rotational mounting is performed, and  FIG. 7B  shows the case where a slide mounting is performed. As shown in  FIGS. 7A and 7B , the electric connection pin  30  that is provided on the carriage  2  and the contact substrate  20  of the print head  1  face each other, and the print head  1  is mounted onto the carriage  2 . Here, in any method, it is configured so that a terminal that is arranged at the lowest part in the z direction is first connected with the electric connection pin  30 . 
     In the case where the rotational mounting shown in  FIG. 7A  is performed, the lower end portion in the z direction in the surface of the print head  1  facing the electric connection pin  30  is brought close to the electric connection pin  30 , and the print head  1  is rotated in the clockwise direction when the drawing is viewed from the front while utilizing the end portion as a supporting point. Accordingly, the VSS  24  arranged at the lower part in the z direction is first connected to the electric connection pin  30 , or the DATA  21  and the VSS  24  are simultaneously connected to the electric connection pin  30 . 
     In the case where the slide mounting shown in  FIG. 7B  is performed, there is adopted a configuration of projecting an electric connection pin to be connected with the VSS  24  toward the y direction (toward the outside) more than other electric connection pins, and thus the VSS  24  is first connected to the electric connection pin, or the DATA  21  and the VSS  24  are simultaneously connected to the electric connection pin. In this case, the electric connection pin to be connected with the VSS  24  is set to have a length that is equal to or longer than the length of an electric connection pin to be connected with the DATA  21 . 
     When the mounting method explained referring to  FIGS. 7A and 7B  is to be adopted in the arrangement of terminals explained referring to  FIGS. 4A and 4B , the VSS  24  is first connected to the electric connection pin  30  and, at the same time or subsequently, the DATA  21  is connected to the electric connection pin  30 . Accordingly, latch-up generated in the case or the like where the VSS  24  is connected after the DATA  21  is connected to the electric connection pin  30 , can be prevented. In this way, here, latch-up can be prevented by adopting a mounting method in which the VSS  24  is first connected to the electric connection pin  30 , or the DATA  21  and the VSS  24  are simultaneously connected to the electric connection pin  30 . 
     Note that, in both configurations shown in  FIGS. 4A and 4B , the VSS  24  is arranged at both ends of the terminal row at the lowermost part in the z direction. In the case where the print head  1  is mounted on the carriage  2  by arranging the VSS  24  in this way, even if the print head  1  makes partial contact with the carriage  2 , the electric connection pin  30  can be first connected to either of the VSSs  24  at both ends, or can be simultaneously connected to the DATA  21  and the VSS  24 . 
       FIG. 4B  shows a configuration in which the VDD  25  is arranged at both ends in the x direction of a terminal row in a position close to the print element substrate  13  next to the terminal row at the lowermost part in the z direction. In the case of the configuration, when performing rotational mounting as shown in  FIG. 7A , the VSS  24  is first connected to the electric connection pin  30 , subsequently, the VDD  25  is connected to the electric connection pin  30 , and the GNDH  22  and the VH  23  are connected after being brought into a state where a logic voltage is applied to the DATA  21 . As described above, here, the VSS  24  and the VDD  25  can be connected to the electric connection pin  30  prior to the VH  23  and the GNDH  22 . Note that the arrangement of the VDD  25  is not limited to the position shown in  FIG. 4B , but the VDD  25  may be arranged in any position, only if it is a position that is connected to the electric connection pin  30  after the VSS  24 . 
     As described above, here, there can be prevented the generation of latch-up caused by the connection or the like of a contact point of a signal system to an electric connection pin before the connection of a contact point of a ground system to the electric connection pin. 
       FIGS. 8A to 8C  are schematic views showing other examples of a layout of terminals. Specifically,  FIGS. 8A to 8C  are schematic views showing examples of the positional relationship between the DATA  21  and the VSS  24  in a configuration similar to the configuration shown in  FIG. 5 . In  FIGS. 8A to 8C , terminal rows of three rows that are constituted, respectively, of four terminals. Note that, in  FIGS. 8A to 8C , illustration of wirings is omitted. Furthermore, also in the cases shown in  FIGS. 8A to 8C , the print head  1  is assumed to be mounted onto the carriage  2  by the mounting method described in  FIG. 7A or 7B . 
       FIG. 8A  shows an example in which one VSS  24  is arranged next to the DATA  21  in the central portion of the terminal row in the x direction. Even in the arrangement, the VSS  24  can be connected to the electric connection pin  30  at the same time as the DATA  21  or prior to the DATA  21 .  FIG. 8B  shows an example in which the VSS  24  is arranged on both adjacent sides of the DATA  21 . Furthermore,  FIG. 8C  shows an example in which the VSS  24  is arranged at both ends in the x direction. In consideration of partial contact or the like in mounting the print head  1  onto the carriage  2 , two or more VSSs  24  are more preferably arranged so as to sandwich the DATA  21 , as in  FIGS. 8B and 8C . 
     The above-described print head can also be used for: apparatuses such as a copier, a facsimile machine having a communication system and a word processor having a print unit; industrial print apparatuses combined compositely with various types of processing apparatuses; and the like. 
     In the above-described embodiments, the print head to be used in print apparatuses has been explained as a liquid ejecting head, but the present invention can also be applied to various types of liquid ejecting heads other than the print head. Furthermore, in the embodiments, the case where ink is used as a liquid to be ejected from the liquid ejecting head has been explained, but a liquid such as various processing liquid other than ink may be used as the liquid. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2015-104492, filed May 22, 2015, which is hereby incorporated by reference herein in its entirety.