Patent Publication Number: US-4060804-A

Title: Ink jet recording method and apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink jet recording method and an apparatus, and more particularly to such a recording method and apparatus which are suitable for recording and reproducing a large size pattern. 
     2. Description of the Prior Art 
     Many patents have been known which concern ink jet recording method and/or apparatus. One typical apparatus is disclosed in the U.S. Pat. No. 3,596,275 to Richard G. Sweet, issued July 27, 1971. As is shown in FIGS. 1 and 12A of the patent, ink droplets 188 are deposited on a record sheet 186 to form a pattern while ink droplets 180 impinge a collector 182 and are recovered thereby. In this recording apparatus, the ink droplets are deflected upwardly and downwardly with respect to a direction of ejection from an ink ejection nozzle 176. In this type of recording apparatus, however, the formation of the ink droplets at a start-up stage is unstable and hence it is difficult to correctly control the deflection, which not only prevents proper pattern recording but also poses a problem of contamination by ejection outside the collector. Accordingly, it is practically advantageous to arrange the collector in the straight flight path of the ink droplets and deflect those ink droplets which are to be used for pattern recording outside a collector area to deposit the droplets onto the record sheet. In such a deflection system, however, the maximum amount of deflection is reduced to one half because the ink droplets can be deflected only in one direction with respect to a straight forward direction of the droplets. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an ink jet recording method and an apparatus which are suitable to reproduce a large size information pattern synthesized by two patterns. 
     It is another object of the present invention to provide an ink jet recording method and an apparatus which allow correct recording of the seam of two patterns. 
     It is a further object of the present invention to provide an ink jet recording method and an apparatus which are suitable to reproduce an information pattern by synthesizing patterns recorded by two ink ejection nozzles. 
     The present invention is characterized in that an information pattern is reproduced by seaming two patterns along those edges which have been recorded by ink droplets less deflected. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a sequence of a record pattern formation in accordance with a recording method of the present invention. 
     FIGS. 2 and 3 show respectively schematic plan and side elevational views of a recording apparatus of the present invention. 
     FIG. 4 shows a perspective view illustrating a recording mode in another embodiment of the present invention. 
     FIGS. 5a to 5d show examples of sketchy versions of records by ink jet, in which FIG. 5d shows an example according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, reference numeral 13A shows a recorded pattern with 13B representing a pattern formed by ink droplets emitted from a first ink ejection nozzle and 13C representing a pattern formed by ink droplets emitted from a second ink ejection nozzle. An arrow X shows the direction of nozzle movement, and the arrow Y shows the direction of deflection of the ink droplets ejected from the first nozzle while the arrow-Y shows the direction of deflection of the ink droplets ejected from the second nozzle. The seam of the patterns 13B and 13C is defined by the edges along a deflection base line 15, which edges are defined by the ink droplets less deflected. 
     Referring now to FIGS. 2, 3 and 4, an ink ejection nozzle 1a, droplet charging electrodes 7a, droplet deflection electrodes 9a and an ink collector 11a constitute a first recording head assembly, and an ink ejection nozzle 1b, droplet charging electrodes 7b, droplet deflection electrodes 9b and an ink collector 11b constitute a second recording head assembly. Each of the head assemblies per se may be of a conventional type. The nozzles 1a and 1b jet pressurized ink from small orifices toward a record sheet 12. The charging electrodes 7a and 7b are arranged at such areas that they establish a static capacitance with the ink column and a leading edge of the ink column is broken while the static capacitance is charged in accordance with an information signal, to form an ink droplet. The deflection electrodes 9a and 9b are arranged on opposite sides of travel paths of the ink droplets, with the electrodes 9a functioning to deflect the ink droplets in the direction Y and the electrodes 9b functioning to deflect the ink droplets in the direction -Y. The collectors 11a and 11b are arranged at positions to enable collection of the ink droplets that travel straightforwards. The recording droplets having a mimimum deflection angle, which avoid the collectors 11a and 11b and are deposited onto the record sheet 12, form those dots which are in line with the deflection base line 15. Record dots are formed on a deflection scan line 14 by deflecting the droplets. A signal representing an information pattern to be recorded is divided into one corresponding to the first pattern 13B and one corresponding the second pattern 13C, and the divided signals are applied to the charging electrodes 7a and 7b respectively so that an information pattern can be reproduced by the synthesis of two patterns as shown in FIG. 4. The deflection scan for the first pattern 13B and that for the second pattern 13C may occur simultaneously or they may occur alternately. When simultaneous scans are effected, information signals are divided into two sections and stored in a memory and they are subsequently read out simultaneously. In the case of alternate scans, a distributor may be used to switch respective signals to the first and second patterns for each of the dots. Since the number of dots on one scan line is usually fixed, the distribution can be readily accomplished by the use of a counter. 
     As is seen from the above description, since those edges of the patterns which are less deflected form the seam, the synthesized information pattern exhibits a clear format because those edges include less deflection distorsion and hence the seam is precisely defined. This will be clear from the comparison of FIGS. 5a to 5d, in which FIG. 5d shows a pattern recorded in accordance with the present method. It is seen that the seam of the first pattern 13B and the second pattern 13C is correctly recorded. It should be noted that the record patterns shown in FIGS. 5a to 5d are sketchy versions and the actual pattern is a gather of dots as shown in FIGS. 2 and 3. 
     While the deflection scan of the ink droplets is made in the above embodiment in the direction starting from a smaller deflection angle to a larger deflection angle, the same effect is attained when the deflection is made in the direction starting from larger deflection angle to smaller deflection angle provided that the seam is formed by the dots recorded by smaller deflection angle. 
     Regarding the physical arrangement of the two record heads, while they are arranged in FIGS. 2 and 3 such that the dots are formed on the deflection scan line 14, they may be arranged such that, as shown in FIG. 4, a scan line 14A for the first pattern 13B and a scan line 14B for the second pattern 13C are split. In the arrangement of FIG. 4, the heads can be mounted perpendicularly to a plane of the record sheet because sufficient mounting spaces for the heads can be allowed, whereas in the arrangements of FIGS. 2 and 3 the heads should be mounted obliquely. In any case, the heads can be arranged without blocking each other while permitting the formation of the patterns having their edges aligned together.