JPH0684077B2 - Inkjet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention ejects ink supplied to a nozzle toward a recording medium to form a series of ink particles, and forms the ink particles in the formation phase. Inkjet recording in which charging is performed in accordance with a recording signal synchronized with the recording signal, and the charged printing ink particles are deflected in accordance with the charge amount to print on the recording medium to form a recording dot. Regarding the device.

(Prior Art and Problems Thereof) FIG. 5 is a diagram showing the operating principle of the ink jet recording apparatus which is the subject of the present invention. As shown in the figure, a gun 1 for producing ink particles is composed of a nozzle 2 and a PZT electrostrictive oscillator 3, and supplies a pressurized ink 4 to the gun 1 and a PZT attached to the nozzle 2. By applying a pulse voltage of a constant frequency to the electrostrictive vibrator 3, the nozzle 2
Ink is ejected from the nozzle hole 2a provided at the tip of the. This ink becomes the ink column 5 having a periodic constriction corresponding to the pulse voltage due to the excitation effect, and the constriction is amplified by the action of the surface tension of the ink as it goes in the traveling direction (recording medium side), and finally the tip thereof. Ink particles 6 are formed from the portion in synchronization with the excitation of the gun 1. Then, the ink particles 6 are charged by the charging electrode 7 to which the recording signal synchronized with the gun excitation is applied, and then proceed between the deflection electrodes 8. Since a DC voltage V is applied to one of the deflecting electrodes 8 and an electric field corresponding to the DC voltage V is generated between the deflecting electrodes 8, the charged ink particles have a fixed direction determined by the charge amount and the electric field strength. Biased to. As a result, only particles necessary for printing (hereinafter referred to as “printing ink particles”) are guided onto the recording medium 9 with an appropriate flight path. On the other hand, particles unnecessary for printing are collected by the gutter 10.

As can be seen from the above recording principle, the ink particles 6
In order to properly adjust the charge amount of the (ink particles for printing), reliable charge control by the charge signal to the ink particles 6 is important. For that purpose, the ink particles 6 are separated from the ink column 5. A recording signal of a predetermined magnitude must be applied to the charging electrode 7 instantly.

By the way, in the case where the ink particles 6 are generated at the positions indicated by ↑ in the same figure (b) with respect to the excitation voltage of the gun 1 shown in FIG. 6 (a), the case shown in the same figure (e) is shown. When the ink particles 6 are charged with a recording signal having such a pulse width and a signal phase, one ink particle is reliably charged and normal recording can be performed. However, the ink particles 6
The phase of separation from the ink column 5 (hereinafter referred to as “ink particle generation phase”) varies due to changes in operating conditions of the gun 1, changes in ink physical properties, and the like. Therefore, due to fluctuations in the ink particle generation phase that inevitably occur in the operating state of the device,
When the generation position of the ink particles 6 fluctuates, for example, from the position of the ↑ mark in the same figure (b) to the position of the ↑ mark in the same figure (c) and the position of the ↑ mark in the same figure (d), the generated ink particles 6 become The recording signal becomes charged in the transient portion of the recording signal shown in FIG. 7E, which causes recording disorder.

Therefore, as a technique for preventing the recording disorder due to the deterioration of the phase relation, an automatic phase matching technique (for example, Japanese Patent Publication No. Sho 55-25068) has been proposed.

In Japanese Examined Patent Publication No. 55-25068, as shown in FIG. 7 (a),
The ink particles 6a (black circles) to be used for forming the recording dots are wetted, and the ink particles existing every three of the ink particles 6 formed every other ink are used for phase detection. It is used as 6b (hereinafter referred to as “phase detection ink particles”) (a circle marked with “X”), and the group C of the phase detection ink particles 6b is collectively formed by a detection electrode provided on its flight path. The charge amount is detected, a phase detection signal as shown in FIG. 7B is detected, the signal is rectified, and then it is determined whether or not the charge state of the phase detection ink particles 6b is a predetermined value or more. It is determined whether or not the phase of the recording signal with respect to the formation of the particles 6 is in a good state.

However, the phase detection signal may have noise having the same frequency as the frequency of the signal. In such cases,
The above device may cause a malfunction. For example, the 8th
As shown in the figure, it is assumed that the phase detection signal S is influenced by noise in the interval t _1, the amplitude value of the phase detection signal S in the interval t ₁ becomes considerably larger than that in the section t ₁ other sections. In such a case, in the above apparatus, when the relationship between the ink particle formation phase and the phase of the recording signal is determined based on the signal in the section other than the section t ₁ of the phase detection signal S, the phase detection ink particle The charge state of 6b is determined to be less than a predetermined value and is accurately determined to be not a good state, but when it is determined based on the signal in the interval t _1, it is incorrectly determined to be a good state. May be done.

(Object of the Invention) The present invention has been made to solve the above problems, and stably and accurately detects the relationship between the ink particle generation phase and the recording signal phase without being affected by noise. It is an object of the present invention to provide an inkjet recording device capable of performing the above.

(Means for Achieving the Purpose) The present invention ejects ink supplied to a nozzle toward a recording medium to form a series of ink particles, and the recording signal synchronized with the formation phase of the ink particles. An ink jet recording apparatus, which is charged according to the above, prints on the recording medium by deflecting the charged printing ink particles according to the charge amount, and forms recording dots,
To achieve the above object, all of the first ink particle group formed by a plurality of consecutive ink particles selected based on a chopper signal of a predetermined phase among the ink particles excluding the printing ink particles Alternatively, while a part of the second ink particle group is continuously charged, the second ink particle group formed by a plurality of continuous particles is entirely uncharged or oppositely charged, and the charge amount of the first and second ink particle groups is increased. A detection electrode for detecting the charge is provided, a binary level signal corresponding to the charge amount is generated from the detection signal generated by the detection electrode corresponding to the charge amount, and a counter is further operated based on the signal. Count operation to obtain the count value,
The phase relationship between the generation phase of the ink particles and the phase of the recording signal is detected based on the count value.

(Embodiment) FIG. 1 is a configuration block diagram showing an embodiment of an ink jet recording apparatus according to the present invention, and FIG. 2 is an explanatory view for explaining the operation of the apparatus shown in FIG. The waveform of each part in FIG. 1 and the charged state of the ink particles are shown.

As shown in FIG. 1, the signal S ₁ shown in FIG. 2 is output from the clock generation circuit 11, and this signal S ₁ is frequency-divided by the frequency dividing circuit 12 to generate the signal S ₂ and the amplification circuit 13 is generated. It is applied to the PZT electrostrictive oscillator 3 via the. As a result, the PZT electrostrictive oscillator 3 vibrates in synchronization with the clock cycle of the signal S ₂ , and the pressurized ink 4 is ejected and atomized to form ink particles 6.

Further, in order to charge the atomized ink particles 6 in accordance with the printing information or the like, the signal S ₁ and the signals S ₃ and S ₄ are supplied from the clock generation circuit 11 and the phase control circuit 14, respectively, to the charging voltage generation circuit 15. Is applied to the charge voltage generating circuit 15 to generate a signal S ₅ based on these signals S ₁ , S ₃ and S _4, and
S ₅ is amplified by the amplifier circuit 16 and then applied to the charging electrode 7. That is, in the phase detection signal generation circuit 17, the signal S ₁ is appropriately processed based on the signal S ₄ from the phase control circuit 14 and the four types of signals S ₆ a, S ₆ b, S ₆ shown in FIG. One of the signals c and S ₆ d is created and output as the signal S ₆ . Further, the signal S ₁ is input to the frequency dividing circuit 18, and a chopper signal S ₇ having a cycle sufficiently larger than the cycle of the signal S ₂ (formation cycle of the ink particles 6) is created. Then, the AND circuit 19 obtains the logical product of the signal S ₆ and the chopper signal S _7, and the second
The signal S ₈ shown is produced. Based on this signal S _8, which particles of ink particles 6 as detailed later is charged by a predetermined amount for the phase detection is controlled. In the recording signal generation circuit 20, the signal S ₉ shown in FIG. 2 is created based on the signal S ₁ , the signal S ₃ from the phase control circuit 14 and the image data applied from the image memory (not shown). . Based on this signal S ₉ , as will be described in detail later, which of the ink particles 6 is charged for printing and corresponding to the image data is controlled. The second
As can be seen from the figure, the pulse width of the signal S ₉ is wider than that of the signal S ₆ , but the reason is that the ink particle generation phase (signal S ₂ ) and the recording signal phase (signal S ₉ ) are slightly different. This is because even in the case of recording, the recording dots can be printed on the recording medium 9. Then, the signal S ₈ and the signal S ₉ are combined by the combining circuit 21 to create the signal S ₅ of FIG.

When this signal S ₅ is amplified by the amplifier circuit 16 and then applied to the charging electrode 7, the position detection ink particles 6b (marked with a cross mark) are applied at the timings corresponding to the peaks p ₁ , p ₂ , ... Of the signal S _5. (Fig. 2) is formed, and the ink particles 6 for phase detection are deflected by the electric field formed between the deflection electrodes 8 to take the flight path 22 and be collected in the gutter 10. On the other hand, the printing ink particles 6a (black circles) (FIG. 2) are formed at the timings corresponding to the peaks p ₁ ′, p ₂ ′, ... , The flight path is deflected by the electric field formed between the deflection electrodes 8.
23 is taken and printed on the recording medium 9. The ink particles 6 are not charged at timings other than these peaks p ₁ , p ₂ , ..., P ₁ ′, p ₂ ′, ... Hereinafter, “uncharged ink particles” 6c (white circles) (FIG. 2) are taken by the gutter 10 through the flight path 24.

That is, in this embodiment, is formed as shown in FIG. 2, among the ink particles 6 except for the ink particles 6a indicia shooting, the six ink particles continuously selected based on the chopper signal S ₇ For the first ink particle group A, all of them are charged by a predetermined amount to form the phase detection ink particles 6b, while for the second ink particle group B formed by 6 ink particles which are continuously continuous. All of them are uncharged to form uncharged ink particles 6c.

The ink particles (the phase detection ink particles 6b and the non-charged ink particles 6c) collected in the gutter 10 pass through the detection electrode 25 and are collected in an ink recovery tank (not shown), and the pressure ink is applied by a predetermined mechanism. It is reused as 4. At this time, when the phase detection ink particles 6b pass through the detection electrode 25, the charge amount of the ink particles 6b is converted into a current amount by the detection electrode 25 and is extracted as a detection signal. This detection signal is input to the detection circuit 26, a binary level signal corresponding to the charge amount is created, and the count value is obtained based on the signal. That is, the detection circuit 26 is an amplifier circuit.
27, bandpass filter 28, half-wave rectifier circuit 29, integrator circuit 3
0, a comparator 31 and a counter 32, the detection signal is amplified by an amplifier circuit 27, then its noise component is removed by a bandpass filter 28, and half-wave rectified by a half-wave rectifier circuit 29. A signal S ₁₀ is produced as shown in FIG.

This signal S ₁₀ is subjected to integration processing by the integration circuit 30, and then it is judged by the comparator 31 whether it is larger than a preset value or not, and a binary level signal S ₁₁ is created. This signal S ₁₁ is input to the input terminal IN of the counter 32. The signal S ₁ from the clock generation circuit 11 is input to the clock input terminal CK of the counter 32, and the phase control circuit
The reset signal S _R is input to the reset input terminal R from 14 and the count value is output to the phase control circuit 14 from the output terminal OUT.
During the period from the application of S _R to the application of the next reset signal S _R , for example, the counting operation is continued based on the signal S ₁ only in the section where the signal S ₁₁ is at “H” level, and the count value Is required.

Next, regarding the operation of the inkjet recording apparatus,
Description will be made with reference to the drawings. First, the signal from the phase control circuit 14
The signal S ₄ indicating that the signal S ₆ a should be selected from among the four types of signals S ₆ a, S ₆ b, S ₆ c, S ₆ d shown in FIG. 2 as S ₆ is the phase detection signal generation circuit 17 (Step S1). However, here, the signals S ₆ a, S ₆ b, S ₆ are selected as candidates for the optimum charging timing.
Although the four types of c and S ₆ d are listed, the present invention is not limited to these.

As a result, the phase detection signal generation circuit 17 outputs the signal S ₆ a. Further, the chopper signal S ₇ is generated signals S ₁ from the clock generating circuit 11 is input to the frequency divider 18, logical product AND circuit between the chopper signal S ₇ and the signal S ₆ 1
The signal S ₈ is generated as determined by 9. Meanwhile, the signal S ₈
In parallel with the production of the above, the recording signal generating circuit 20 produces the signal S ₉ based on the signals S ₃ and S ₁ given from the phase control circuit 14 and the image data from the image memory (not shown). Then, the signal S ₈ and the signal S ₉ are combined into a synthesis circuit.
The synthesized signal S ₅ is created by the synthesis circuit 21 and the amplification circuit 16
After being amplified by, it is applied to the charging electrode 7. As a result, the printing ink particles 6a fly on the flight path 23 and are printed at a predetermined position on the recording medium 9, while the phase detection ink particles 6b and the non-charged ink particles 6c fly. They fly over 24 and are collected by Gutter 10. Then, the phase detection ink particles 6b and the non-charged ink particles 6c collected in the gutter 10 are collected in an ink tank (not shown) via the detection electrode 25. Further, the detection signal extracted from the detection electrode 25 is amplified by the amplification circuit 27, the noise component is removed by the bandpass filter 28, and half-wave rectified by the half-wave rectification circuit 29 to obtain the signal S ₁₀ .

This signal S ₁₀ is subjected to integration processing by the integrating circuit 30, and then is compared with the reference set value by the comparator 31, and a signal S ₁₁ representing the comparison result is given to the input side of the counter 32. Now, assuming that the phase of the signal S ₆ a does not match the formation phase of the ink particles 6 and the detection signal extracted from the detection electrode 25 does not include any noise component, the half-wave rectifier circuit 29 The output signal S ₁₀ has an AC waveform composed of only small amplitude components like the signal S ₁₀ a in FIG. 4, and the “L” level signal S ₁₁ a is input to the counter 32 from the comparator 31. On the other hand, this signal S
_In parallel with the input of ₁₁ a, the phase control circuit 14 to the counter 32
The count value is reset signal S _R is input to the reset terminal R is preset, and thereafter in the section T ₂ of the up (see FIG. 4) following the reset signal to the reset terminal R S _R is input, the signal The counting operation of the counter 32 is executed based on S ₁₁ a. In this case, the signal S ₁₁ a is always "L"
Since it is a level, the count value in section T ₂ is “0”
And the signal representing the count value is the phase control circuit 14
And the count value is stored in a memory (not shown) (step S2).

Next, four types of signals shown in FIG. 2 as a signal _{S 6 S 6 a, S 6} b,
A signal S ₄ indicating that the signal S ₆ b should be selected from among S ₆ c and S ₆ d is given to the phase detection signal generation circuit 17 (step S3), and in the same manner as described above, the signal S _{6 is} sent in step S4. The count value corresponding to the phase of b is stored in memory. Now, assuming that the phase of the signal S ₆ b does not match the formation phase of the ink particles 6 and the detection signal extracted from the detection electrode 25 contains a slight noise component, the half-wave rectifier circuit 29. The signal S ₁₀ output from is an AC waveform in which a large amplitude component due to noise is included between small amplitude components like the signal S ₁₀ b in FIG. 4, and the comparator 31 responds to the noise. Signal S having an "H" level section
₁₁ b is output. Therefore, the counter 32 has the interval T ₂
Of, only the counter value "H" level period of the signal S ₁₁ b is incremented, the count value corresponding to the "H" level period of the signal S ₁₁ b are stored in the memory.

After this, the signal S ₆ c,
The same process as described above is performed on S ₆ d, and the respective count values are stored in the memory. For example, assuming that the signal S ₆ c is in phase with the formation phase of the ink particles 6, the signal S ₁₀ output from the half-wave rectifier circuit 29 is
Like the signal S ₁₀ c in the figure, the AC waveform has only a component with a large amplitude, and the comparator 31 outputs the “H” level signal S ₁₁ c. Therefore, the counter 32
Continuously count value in T ₂ is incremented, the count value corresponding to the interval T ₂ is stored in the memory. The signals S ₁₀ d and S ₁₁ d in FIG. 4 are the same as the signals S ₁₀ b and S ₁₁ b, and therefore their explanations are omitted.

Thus, when the count value corresponding to the signal S ₆ a~S ₆ d is obtained, then the routine proceeds to step S9, the four count values stored in the memory are compared, the signal corresponding to the maximum count value ( For example, the signal 6c) is determined to be the phase representing the optimum charging timing (step S9). Thereafter, the process proceeds to step S10, to match the phase of the signal S ₉ to a phase of the signal S ₆ (e.g., signal S ₆ c).

As described above, of the ink particles 6 excluding the printing ink particles 6a, all of the first ink particle group A formed by six consecutive ink particles selected based on the chopper signal S ₇ of a predetermined phase While charging all of the second ink particle group B formed by six consecutive ink particles, the charge amount of the first and second ink particle groups A and B is detected. A detection electrode 25 is provided, and a binary level signal S ₁₁ corresponding to the charge amount is generated from the detection signal generated by the detection electrode 25 corresponding to the charge amount, and a counter is generated based on the signal S _11. The count value is obtained by counting 32, and the phase relationship between the generation phase of the ink particles 6 and the phase of the recording signal S ₉ is detected based on the count value. Particle generation phase and recorded signal The relationship with the phase can be detected stably and accurately. In particular, as shown in FIG.
Signals S ₆ a, S ₆ b, S ₆ c, S ₆ d having different phases are prepared, and the phases of these signals ₆ a, S ₆ b, S ₆ c, S ₆ d and the ink particle generation phase are prepared. By obtaining the respective phase relationships with and as count values, and comparing the count values, the phase of the recording signal most suitable for the ink particle generation phase, that is, the charging timing, is obtained by four types of signals S ₆ a, S ₆ b. , S ₆ c, S ₆ d.

Although the first ink particle group A is charged with a predetermined amount in the above embodiment, the present invention is not limited to this, and a part of the first ink particle group A, for example, 1 may be charged. It is needless to say that a predetermined amount may be charged every other unit.

Further, in the above embodiment, all of the second ink particle group B is uncharged, but instead of this, all of the second ink particle group B may be oppositely charged by an appropriate means. .

(Effects of the Invention) As described above, according to the inkjet recording apparatus of the present invention, among the ink particles excluding the ink particles for printing, a plurality of continuous particles selected based on the chopper signal of a predetermined phase are formed. All or part of the first ink particle group is charged, and then all of the second ink particle group formed by a plurality of consecutive ink particles is uncharged or oppositely charged. First and second
A detection electrode for detecting the charge amount of the ink particle group is provided, and a binary level signal corresponding to the charge amount is generated from a detection signal generated by the detection electrode corresponding to the charge amount. The counter is counted based on the signal to obtain the count value, and the phase relationship between the generation phase of the ink particles and the phase of the recording signal is detected based on the count value, so that it is affected by noise. Therefore, there is an effect that the relationship between the ink particle generation phase and the recording signal phase can be detected stably and accurately.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of an inkjet recording apparatus according to the present invention, FIG. 2 is an explanatory diagram for explaining the operation of the apparatus, and FIG. 3 is a diagram of the apparatus. FIG. 4 is an operation flowchart, FIG. 4 is an explanatory diagram for explaining the operation of the detection circuit of the apparatus, and FIG. 5 is a partial configuration diagram for explaining the operation principle of the inkjet recording apparatus. FIG. 6 is an explanatory diagram for explaining the phase relationship between the gun excitation voltage and the charging potential in the inkjet recording device, and FIG. 7 is an explanatory diagram for explaining the operation of the conventional inkjet recording device. FIG. 8 is a diagram showing a phase detection signal of the device. 2 ... Nozzle, 4 ... Pressurized ink, 6 ... Ink particle, 6a ... Printing ink particle, 9 ... Recording medium, 25 ... Detection electrode, 32 ... Counter, A ... First ink particles, B ...... second ink particles, S ₇ ...... chopper signal, S ₁₁ ...... signals

Continuation of front page (56) Reference JP-A-58-171970 (JP, A) JP-A-50-60131 (JP, A) JP-B-58-24277 (JP, B2)

Claims (1)

[Claims] 1. An ink supplied to a nozzle is ejected toward a recording medium to form a series of ink particles, and the ink particles are charged according to a recording signal synchronized with the formation phase, and this charging is performed. An ink jet recording apparatus, wherein the printed ink particles are deflected in accordance with the charge amount and printed on the recording medium to form recording dots, wherein the printing ink particles are removed. All or part of a first ink particle group formed by a plurality of consecutive ink particles selected based on a chopper signal of a predetermined phase is charged, and subsequently formed by a plurality of consecutive ink particles. The entire second ink particle group is charged non-charged or oppositely charged, and a detection electrode for detecting the charge amount of the first and second ink particle groups is provided. A binary level signal corresponding to the charge amount is generated from the detection signal generated corresponding to the charge amount, the counter is counted based on the signal to obtain the count value, and the count value is calculated based on the count value. The inkjet recording apparatus is configured to detect a phase relationship between the generation phase of the ink particles and the phase of the recording signal.