JPH0114031B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a charge deflection type inkjet recording device. Generally, in a charge deflection type inkjet recording device, ink droplets are charged and deflected according to printing information, and are printed on a recording paper. At this time, each ink droplet creates an air flow behind it, and when the subsequent ink droplet enters this airflow, the air resistance of the subsequent ink droplet decreases, so the preceding and following ink droplets approach each other. or they may combine to cause printing distortion. Furthermore, since printing ink droplets are electrically charged, Coulomb force acts between each charged ink droplet, and this Coulomb force disturbs the spacing between each ink droplet, causing printing distortion. Furthermore, the amount of charge of the ink droplet that is about to be charged is reduced by the influence of the preceding charged ink droplet, which also causes printing distortion. For example, US Pat. No. 3,946,399 has been proposed to solve these drawbacks.
The invention of U.S. Pat. No. 3,946,399 detects the printed pattern in advance and corrects the amount of charge according to the pattern in order to compensate for the mutual influence of charged ink droplets due to Coulomb force and deflection distortion due to air resistance. The number of deflection stages is 32.
When the number of steps increases, it becomes ineffective. The reason for this is that as the number of deflection stages increases, the amount of distortion increases because the ink droplets fly close together, and since the time the ink droplets are flying varies depending on the amount of deflection, the amount of distortion increases depending on the amount of deflection. This is because the amounts of
That is, when an image is formed by sequentially flying ink droplets, a plurality of charged ink droplets influence each other, resulting in the following three types of distortion. (i) Induced distortion Printing distortion that occurs when ink droplets are charged in a state that deviates from the normal value due to the influence of the charge of preceding ink droplets. (ii) Distortion due to Coulomb force Printing distortion that occurs when the flight path of an ink droplet changes due to the influence of the charge of the preceding droplet and the connecting droplet (i.e., repulsion in the case of the same polar charge) when the ink droplet is flying. . (iii) Distortion due to changes in air resistance When an ink droplet is flying, the air resistance changes due to the flight of the preceding droplet, and the flying speed changes, resulting in printing distortion. Since the above-mentioned printing distortion differs depending on the deflection stage, the amount of correction for correcting the printing distortion of ink droplets printed at the position of a particular deflection stage is different in the above three cases. It is necessary to calculate the distortion due to the influence of preceding and succeeding ink droplets by comprehensively adding them according to each deflection stage. The present invention has been made in view of the above-mentioned circumstances, and will be described in detail below with reference to the drawings. FIG. 1 is a main part electric circuit diagram for explaining one embodiment of the present invention, in which 1 is a clock pulse generation circuit, 2 is a frequency divider circuit, 3 is a phase shift circuit, 4 and 5
is an amplifier, 6 is a search pulse generation circuit, 7 is a charge correction circuit, 8 is a digital-analog (D/A) conversion circuit, 9 is an amplifier, and the excitation frequency of the head is
Assume that at 132 kHz, two guard drops are provided to reduce distortion, but these guard drops are not necessarily required. Therefore, the charging frequency to the ink droplet is 44kHz. Note that the charging voltage is variable from 50 to 240V depending on the input.
In FIG. 1, a clock pulse generated by a clock pulse generating circuit 1 has a frequency of 1056 kHz, and is divided into 1/8, 1/3, and 1/24 by a frequency dividing circuit. The signal f ₁ divided by 1/8 is an excitation pulse with a particulation frequency of 132 kHz, the signal f ₂ divided by 1/24 is a charging pulse of 44 kHz, and the signal f ₃ divided by 1/3 is 352 kHz. This is the correction clock. The charge correction circuit 7 stores correction amounts, sequentially reads out the correction amounts, and controls whether or not to add them depending on the presence or absence of corresponding data.The result of the addition is as follows. The signal is converted into an analog signal by the D/A conversion circuit 8 and applied to the charged electrode through the amplifier 9. For this reason, the correction amount is stored as a binary code in a memory such as ROM or RAM in the charge correction circuit 7, and together with this correction amount, each ink droplet reaches a predetermined position when it is deflected independently. Basic charge codes such as these are also stored at the same time. This is shown in Figure 2. In Figure 2, F ₃ to F ₁
is the correction amount for correcting the influence of subsequent ink droplets, P ₁ to _P4 is the correction amount for correcting the influence of preceding ink droplets, and Vcs is the correction amount for correcting the influence of preceding ink droplets, and Vcs is the correction amount for correcting the influence of preceding ink droplets. The basic charge amount (basic charge code) is defined as , and this basic charge amount is non-linear as will be described later. Also,
In the example shown, each charge code is 11 bits,
This is divided into 3 bits, 4 bits, and 4 bits and displayed in octal, hexadecimal, and hexadecimal. Therefore, it is sufficient that the memory has an 11-bit parallel configuration and has a number of bits of 11 (bits) x 8 (dots) x 32 (stages) or more. Note that the code of 7FF in the 31st stage _F2 is such that complements are added to implement -1. Also,
The basic charge code (Vcs) of a single ink droplet is non-linear because the air resistance varies depending on the amount of deflection, and the individual correction amounts (P ₁ to P ₄ , F ₃ ~F ₁ ) is determined based on this single ink droplet, but the basic charge code (Vcs) and correction amount (P ₁ ~ _{P 4} , F ₃ ~ _{F 1} ) are determined based on computer simulation results. It is calculated from , and is further revised and determined through experiments. FIG. 3 is a schematic diagram of the main parts of the charge correction circuit 7, in which 7a is a charge code determining section, 7b is a memory,
7c is a charge code generating section. FIG. 4 is a detailed diagram of the circuit shown in FIG. 3, in which 11 is an address counter, 12 is a memory (ROM), 13 is a gate circuit, 14 is an adder, 1
5 is a shift register, 16 is a multiplexer, 1
7 is a latch circuit, 18 is a D/Q flip-flop circuit, and 19 is a gate circuit. Further, FIG. 5 is a diagram showing the reading of eight correction data and the time point at which the non-linear correction amount is added to the adder, etc., where a is one period of the charging pulse, and b is the lower three of the output of the address counter 11. The contents of the bit, c indicates the readout of correction data, and d indicates the correspondence with the shift register output, and the operation is as follows. (1) When the print signal becomes high level, the address counter 11 becomes operational, and the address counter 11 counts up (+1) as 0, 1, 2, 3, etc. at the rising (or falling) of the correction clock _f3 . ) and is counted up, so that the lower three bits repeat 0-7, 0-7, and so on. Therefore, the lower 3 bits are displayed as 0 to 7 as shown in the table.
When the upper 5 bits are indicated as 0 to 31 as shown in the table, when the address counter 11 is 0, 0, the deflection stage is 1 and the correction value of F3 is selected, and when the address counter ₁₁ is 0, 1, the deflection stage is 1 and the F3 correction value is selected. A correction value of ₂ is selected. Similarly, when the values are 1 and 0, the number of deflection stages is 2, the correction value of _F3 is 31 and 7, and the correction value of _P4 is selected when the number of deflection stages is 32. On the other hand, since the lower three bits are introduced into the multiplexer, the relationship between the lower three bits and the output of the multiplexer is as shown in the table.

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【table】

Claims (1)

[Claims] 1 In an inkjet recording device that selectively charges ink droplets continuously ejected from an inkjet head depending on the presence or absence of printing data, and prints on recording paper by deflecting them according to the amount of charge, the The amount of charge corresponding to the deflection stage of the ink droplet to be charged and the printing on the ink droplet to be deflected by each of the preceding and subsequent ink droplets for each of the preceding and following ink droplets of the ink droplet to be charged. storage means for storing an independent correction amount for each ink droplet of distortion; readout means for reading out the correction amount from the storage means; and an addition means for selectively adding each of the independent correction amounts to the charge amount, and the selected ink droplet is charged in accordance with the charge amount output from the addition means. Inkjet recording device.