Abstract:
A nozzle for issuing ink liquid, a vibrator for exciting the nozzle to emit ink droplets of a given frequency, and a charging electrode for charging the ink droplets in accordance with print information are arranged within a cylinder shaped housing. One end of the cylinder shaped housing is covered by a wall having an opening at the center thereof through which charged ink droplets are propelled. A fixing plate is attached to the other end of the cylinder shaped housing for tightly securing the nozzle, the vibrator and the charging electrode within the cylinder shaped housing.

Description:
This application is a continuation, of copending application Ser. No. 839,392, filed on Oct. 4, 1977 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an ink jet system printer of the charge amplitude controlling type and, more particularly, to a printer head of an ink jet system printer for emitting charged ink droplets. 
     Generally, in an ink jet system printer of the charge amplitude controlling type, a stream of ink droplets having a given frequency is emitted from a nozzle toward a record receiving paper and each ink droplet is charged to a desired amplitude in accordance with a video signal through the use of a charging electrode. Each ink droplet is deflected in the vertical direction as it passes through a fixed high voltage field established by a pair of deflection plates in accordance with the charge amplitude carried thereon and deposited on the record receiving paper. The nozzle, a vibrator for exciting the nozzle at the given frequency, and the charging electrode are mounted on a carriage which is driven to travel in the horizontal direction at a fixed speed during print operation, whereby printing is performed in a dot matrix fashion. 
     A typical construction of the ink jet system printer of the charge amplitude controlling type is disclosed in U.S. Pat. No. 3,555,558 entitled &#34;INK DROP WRITING APPARATUS WITH DATA SYNCHRONIZING MEANS&#34; patented on Jan. 12, 1971. An example of a carriage drive mechanism is described in U.S. Pat. No. 4,050,076 entitled &#34;DEFLECTION MEANS INCLUDING A DEFLECTION ELECTRODE MOUNTED ON A TRAVELLING CARRIAGE IN AN INK JET SYSTEM PRINTER&#34; issued on Sept. 20, 1977. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a novel printer head including a nozzle, an electromechanical transducer and a charging electrode in an ink jet system printer of the charge amplitude controlling type. 
     Another object of the present invention is to facilitate installation of a printer head on a carriage in an ink jet system printer of the charge amplitude controlling type. 
     Still another object of the present invention is to provide a printer head of a compact size for use in an ink jet system printer of the charge amplitude controlling type. 
     Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     To achieve the above objects, pursuant to an embodiment of the present invention, a nozzle for issuing ink liquid, a vibrator for exciting the nozzle to emit ink droplets of a given frequency, a charging electrode for charging the ink droplets in accordance with print information, and a sensing electrode for detecting the charge on the ink droplets are installed within a cylinder shaped housing. One end of the cylinder shaped housing is covered by a wall having an opening at the center thereof through which charged ink droplets are propelled. A fixing plate is attached to the other end of the cylinder shaped housing for tightly securing the nozzle, the vibrator, the charging electrode and the sensing electrode within the cylinder shaped housing. 
     In a preferred form, the fixing plate is secured to a carriage through the use of screws. The securing of the nozzle, the vibrator, the charging electrode and the sensing electrode within the cylinder shaped housing is adjustable through the use of the screws. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein, 
     FIG. 1 is an exploded perspective view of an embodiment of a printer head of an ink jet system printer of the charge amplitude controlling type of the present invention; and 
     FIG. 2 is a sectional view of the printer head of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows an exploded printer head of an embodiment of the present invention and a carriage for carrying the printer head. 
     A carriage 10 mainly comprises a supporter 11 for slidably supporting the carriage 10 on a shaft 20, a cylinder hole 12 provided below the supporter 11, and an extended leaf 13. The cylinder hole 12 functions to accommodate a printer head, and a wire 21 is fixed to the extended leaf 13 for driving the carriage 10 along the shaft 20. 
     A slim deflection electrode 22 is secured to the carriage 10. The slim deflection electrode 22 is maintained at the ground potential and functions to create a constant high-voltage deflection field in combination with a counter deflection electrode mounted on the body of the ink jet system printer (not shown). Detailed constructions of the slim deflection electrode 22 and the carriage drive mechanism are described in U.S. Pat. No. 4,050,076 entitled &#34;DEFLECTION MEANS INCLUDING A DEFLECTION ELECTRODE MOUNTED ON A TRAVELLING CARRIAGE IN AN INK JET SYSTEM PRINTER&#34; issued on Sept. 20, 1977. 
     The bottom end of the extended leaf 13 branches to form a guide section 13A which is associated with a guide shaft 23. With such an arrangement, the carriage 10 is driven to travel in the horizontal direction, or, along the shaft 20 and the guide shaft 23. The horizontal direction corresponds to the row direction of a matrix pattern to be printed. 
     A printer head 30 mainly comprises a cylinder shaped housing 31 one end of which is covered by a wall, a supporting plate 32 integrally secured to the other end of the cylinder shaped housing 31, and a fixing plate 33 for covering the opening of the cylinder shaped housing 31. The supporting plate 32 and the fixing plate 33 function, in combination, to secure the printer head 30 to the carriage 10. The fixing plate 33 also functions to tightly secure various components of the printer head within the cylinder shaped housing 31. 
     An opening 31A is formed in the wall covering one end of the cylinder shaped housing 31. A guide slit 31B is provided along the longitudinal axis of the cylinder shaped housing 31 for guiding the various components of the printer head to predetermined positions within the cylinder shaped housing 31. 
     The supporting plate 32 has tapped holes 32A, and the fixing plate 33 has tapped holes 33C. The fixing plate 33 is attached to the extended leaf 13 of the carriage 10 with the intervention of the supporting plate 32 through the use of screws secured through the tapped holes 32A and 33C. The cylinder shaped housing 31 is installed within the cylinder hole 12 of the carriage 10. Control signal transmission cables 34 are engaged to a supporter 32B integral with the supporting plate 32 for applying control signals to the printer head. 
     A phase sensor 41 is installed within the cylinder shaped housing 31 with the intervention of a shielding metal cap 40 between the wall covering one end of the cylinder shaped housing 31. The phase sensor 41 functions to detect the charge amplitude carried on the ink droplets for achieving the phase synchronization between the application of charging signals and the ink drop separation phase. Detection outputs of the phase sensor 41 are applied to a phase control circuit through a signal line 43. 
     A typical mode of operation of the phase sensor 41 is described in U.S. Pat. No. 3,836,912 entitled &#34;DROP CHARGE SENSING APPARATUS FOR AN INK JET PRINTING SYSTEM&#34; issued on Sept. 17, 1974. A typical construction of the phase sensor 41 is described in detail in U.S. Pat. No. 3,953,860 entitled &#34;CHARGE AMPLITUDE DETECTION FOR INK JET SYSTEM PRINTER&#34; issued on Apr. 27, 1976. 
     An example of the phase synchronization system is described in U.S. Pat. No. 3,769,632 entitled &#34;DIGITAL PHASE CONTROL FOR AN INK JET RECORDING SYSTEM&#34; issued on Oct. 30, 1973. Another example of the phase synchronization system is described in U.S. Pat. No. 4,025,926 entitled &#34;PHASE SYNCHRONIZATION FOR INK JET SYSTEM PRINTER&#34; issued on May 24, 1977. 
     An insulation spacer 42 and a charging electrode 44 is installed within the cylinder shaped housing 31 in such a manner as to contact the phase sensor 41. A signal transmission wire 45 is attached to the charging electrode 44 in order to charge ink droplets in accordance with print information or the video signal. 
     At the back of the charging electrode 44, an insulation spacer 46 and a nozzle 47 are disposed. A screw portion 48 is formed at the rear end of the nozzle 47. An electromechanical transducer 49 is attached to a middle portion 47a of the nozzle 47 with the intervention of an insulation tube 62 (see FIG. 2) therebetween. The electromechanical transducer 49 receives exciting signals through a signal wire 50, whereby ink droplets of a given frequency are emitted from the nozzle 47. A counter weight 51 which has a tapped internal face is engaged to the screw portion 48 of the nozzle 47. 
     The counter weight 51 is made of metal and functions to tightly secure one end of the nozzle 47, whereby the nozzle 47 is vibrated by the electromechanical transducer 49 in a fashion that the counter weight 51 is the fulcrum of the vibration. The counter weight 51 also functions to prevent the transmission of the vibration to other parts of the system. 
     A groove 52 is formed on the side wall of the counter weight 51. The signal wire 50 is secured within the groove 52 and attached to the groove 52 through the use of preferred adhesive. In this way, optimum vibration of the electromechanical transducer 49 is ensured even when tension is erroneously applied to the signal wire 50. The rear end 47b of the nozzle 47 is communicated to an ink liquid supply conduit 53 provided through the counter weight 51. A connection point of the rear end 47b of the nozzle 47 and the ink liquid supply conduit 53 is tightly secured by a holder 54. 
     FIG. 2 is a sectional view of the printer head 30. Like elements corresponding to those of FIG. 1 are indicated by like numerals. A tube 60 is provided around the nozzle 47 and the electromechanical transducer 49 which are interposed between the insulation spacer 46 and the counter weight 51. A resilient insulator 61 made of, for example, silicon resin is disposed between the tube 60 and the nozzle 47 and the electromechanical transducer 49, whereby the vibration of the electromechanical transducer 49 is ensured and the leakage of electric energy from the electromechanical transducer 49 is prevented. The leakage of the electric energy will occur when the resilient insulator 61 is not disposed, since the ink liquid emitted from the nozzle 47 may be filled around the electromechanical transducer 49. 
     The above-mentioned various components of the printer head are not fixed with respect to the cylinder shaped housing 31. The respective positions of the printer head components are fixed by attaching the fixing plate 33 to the open end of the cylinder shaped housing 31. A resilient plate 33A is attached to the fixing plate 33 so that tight connection is achieved between the supporting plate 32 and the fixing plate 33 when the printer head is secured to the carriage 10 through the use of screws and the tapped holes 32A and 33C. An indent 33B is formed in the fixing plate 33 through which the ink liquid supply conduit 53 is disposed. 
     The resilient plate 33A functions to apply a preferred pressure to the printer head components to tightly secure them. And the resilient plate 33A functions to absorb any vibrations occurred within the printer head. 
     An extended leaf 33D is fixed to the upper end of the fixing plate 33. An end of the extended leaf 33D is shaped slim, whereby the slim shaped end of the extended leaf 33D functions as an indicator for indicating the printing position. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications are intended to be included within the scope of the following claims.