JP2817887B2 - Continuous jet type inkjet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous jet type ink jet recording apparatus, and more particularly to adjustment of an ink jet axis (nozzle axis) in a continuous jet type ink jet recording apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 11, for example, a conventional continuous jet type ink jet recording apparatus comprises an ink bottle 91 for storing ink, an ink pump 92 for pressurizing and sending ink, and an ink tube 93 for supplying ink. When,
A nozzle 94 having an ultra-fine circular orifice;
Ink electrode 95 for setting the potential of the ink in 4 to the ground level
A vibrator 96 composed of a piezo vibrator mounted on the nozzle 94, a vibrator driving oscillator 97 for providing an excitation signal to the vibrator 96, and a circular or slit-shaped opening concentric with the nozzle 94 for recording. A control electrode 98 to which a control signal for controlling the charging of the inkjet according to the image signal is applied.
A ground electrode 99 disposed in front of the control electrode 98 and a knife edge 10 attached to the ground electrode 99;
0, a high-voltage DC power supply for deflection (hereinafter simply referred to as deflection power supply) 101 and a deflection power supply 101 connected to a ground electrode 99.
And a deflecting electrode 102 for creating a strong electric field perpendicular to the ink jet axis and deflecting the charged ink particles to the ground electrode 99 side. In FIG. 11, reference numeral 103 denotes a rotating drum around which a recording medium is wound.

In such a conventional continuous jet type ink jet recording apparatus, ink pressurized by an ink pump 92 is guided to a nozzle 94 through an ink tube 93, and an ink jet is formed from an orifice. It splits into rows of ink particles at a value-dependent spontaneous particleization frequency. At this time, the nozzle 94
When the excitation frequency of the vibrator 96 mounted on the vibrator 96 is set near the spontaneous particle generation frequency, the particle generation is synchronized with the excitation of the vibrator 96, and ink particles of a very uniform size are generated in accordance with the excitation frequency.

[0004] When the uniform array of ink particles is binary-charge-modulated by a control signal (recording pulse) whose phase is synchronized with the excitation signal, the charged ink particles are deflected to the ground electrode 99 by the action of a deflection electric field. The uncharged ink particles cut by the knife edge 100 travel straight on the knife edge 100 to record dots on a recording medium wound around the rotating drum 103. Therefore, if a control signal (recording pulse) is made to correspond to a print signal or an image signal, a character or an image is binary recorded on a recording medium.

In order to correctly and stably control recording on / off by a control signal applied to the control electrode 98, it is necessary to provide a sufficient amount of deflection to the ink jet and to determine the position of the ink jet axis (nozzle axis) and the knife edge 100. It is necessary to set the relationship optimally.

[0006] Regarding the deflection amount of the ink jet, in a conventional continuous jet type ink jet recording apparatus which has been put into practical use, the ink jet is charged and modulated at 40 to 150 V,
The deflection amount on the knife edge 100 is 0.1 to 0.4 mm
It is designed to be.

[0007] Regarding the adjustment of the ink jet axis (nozzle axis), in a conventional continuous jet type ink jet recording apparatus that has been put into practical use, for example, as shown in FIG. It is urged and can be adjusted independently at the fulcrum 111 by the adjusting screw 113, and is manually adjusted mechanically.

[0008] The deflection amount of the ink jet is proportional to the control voltage. Therefore, the adjustment position of the inkjet axis (nozzle axis) is optimal when the tip of the knife edge 100 is located at approximately the half point of the inkjet axis when the control voltage is on and off. However, in an actual machine, it is almost impossible to adjust the inkjet axis (nozzle axis) by observing the inkjet axis with a microscope.

Therefore, in practice, the position of the nozzle 94 was adjusted by operating the adjusting screw 113 manually while operating the continuous jet type ink jet recording apparatus and performing test printing.

On the other hand, when the relative position between the ink jet and the garter member (corresponding to a knife edge) is set and adjusted, the substantial deflection amount of the deflection electric field in the ink jet is reduced (for example, to １ ／) from that during normal recording. A continuous ejection type ink jet recording apparatus has been proposed (see JP-A-2-1322). In this continuous ejection type ink jet recording apparatus, it is possible to easily determine whether or not ink particles have hit the garter member by connecting the charge amount detector to the garter member and monitoring the output.

In the description of FIG. 11, the case where the charged ink particles are deflected to the ground electrode 99 side and the uncharged ink particles are made to travel straight on the knife edge 100 and used for recording has been described. . That is, the polarity in which the uncharged rectilinear ink particles are cut by the knife edge 100 and the ink particles used for recording are drawn to the deflecting electrode 102 (positive charging in the case of FIG. 11, ie, a negative control signal is given to the control electrode 98). This is a method in which the charged ink particles are charged, passed through the knife edge 100, and recorded with charged ink particles.

[0012]

In the above-mentioned conventional continuous jet type ink jet recording apparatus, the adjustment screw 113 is manually operated while the continuous jet type ink jet recording apparatus is actually operated to perform test printing. Since the position of (axis) was adjusted, the adjustment was qualitative and there was a problem that confirmation of the above-mentioned bisection point was impossible. That is, since the moment when the ink jet collides with the knife edge 100 in the adjustment process is known, the position of the nozzle 94 can be estimated by the rotation angle of the adjustment screw 113 based on the position. Backlash makes it even more inaccurate.)

Further, since the position of the nozzle 94 is adjusted by manually operating the adjusting screw 113 while actually operating the continuous jet type ink jet recording apparatus, there is a problem that mechanical and electrical dangers are involved.

Further, there is another problem that the recording medium is consumed for adjusting the position of the nozzle 94, which is uneconomical.

Furthermore, when the ink jet collides with the tip of the knife edge 100 in the recording area, there is a problem that the mist contaminates the rotary drum 103 and the like.

On the other hand, in the conventional continuous ejection type ink jet recording apparatus, when the relative position between the ink jet and the garter member is set and adjusted, the amount of deflection of the deflection electric field in the ink jet is made smaller than that in normal recording. Since the amount of deflection at the time of adjustment is only one, it is not possible to confirm the degree of accuracy with which the adjustment has been made. If the mechanical accuracy is not high, precise adjustment is not possible. There is a problem that the continuous ejection type ink jet recording apparatus becomes expensive. In particular, when the charge amount detector is connected to the garter member, the garter member must have an insulating structure. There is a problem that difficulty and complicated structure are involved.

In view of the above points, the inventor of the present application performs a test run of the ink jet with the rotating drum and the carriage stopped in an area not related to recording (hereinafter, referred to as a home position). Continuous ejection type ink jet, which detects the position of the ink jet axis (nozzle axis) by detecting the charge (current) carried by the ink jet passing through the knife edge by giving a minute deflection centered at the half point of A recording device has already been proposed in Japanese Patent Application No. 2-275830.

Further, the inventor of the present application performs a test run of the ink jet while the rotating drum and the carriage are stopped at the home position, gives a continuous (including stepwise) changing deflection to the ink jet, and passes through the knife edge. Japanese Patent Application No. 2-299203 has proposed a continuous ejection type ink jet recording apparatus which detects the position of the ink jet axis (nozzle axis) by detecting the electric charge (current) carried by the ink jet.

An object of the present invention is to provide a continuous jet type ink jet recording apparatus in which the position of the ink jet axis (nozzle axis) can be detected simply and accurately with further improvements. That is, a test run is performed by applying a constant positive (or negative) charge to the inkjet while the rotating drum and the carriage are stopped at the home position, and the ink that collides with the knife edge and scatters is negative (or is induced by the deflection electric field). An object of the present invention is to provide a continuous ejection type ink jet recording apparatus which detects the position of the ink jet axis (nozzle axis) by detecting the positively charged electric charge.

[0020]

According to the present invention, there is provided a continuous jet type ink jet recording apparatus comprising: a particle forming means for dividing an ink jet into a series of ink particles; and a charging means for charging the ink particles formed by the particle forming means. 1 charging means, a deflecting means for creating a deflection electric field orthogonal to the inkjet axis and deflecting the charged ink particles, a separating means for cutting the ink particles deflected by the deflecting means and passing the undeflected ink particles, A second charging means for charging the ink particles colliding and scattered at the tip of the separation means, and capturing the ink particles having passed through the separation means and the ink particles colliding and scattered at the tip of the separation means, and charging the charges. Charge detecting means for detecting, and judging whether or not the ink jet shaft can be adjusted based on the charges detected by the charge detecting means That includes a jet axis adjusting state determining means, and a jet axis adjusting means for adjusting the positional relationship between the separating means and the ink jet axis.

[0021]

In the continuous ink jet recording apparatus of the present invention, the particle forming means divides the ink jet into a series of ink particles, and the first charging means charges the ink particles formed by the particle forming means to deflect the ink. Means for creating a deflection electric field orthogonal to the inkjet axis to deflect the charged ink particles, separating means for cutting the ink particles deflected by the deflecting means and passing undeflected ink particles, Charge the ink particles colliding and scattered at the tip of the ink jet, and the charge detection means captures the ink particles colliding with the tip of the separation means and the ink particles colliding and scattered at the tip of the separation means, and detects the charge, and the inkjet axis adjustment state The determining means determines whether or not the inkjet axis can be adjusted based on the charge detected by the charge detecting means,
Inkjet axis adjusting means adjusts the positional relationship between the inkjet axis and the separating means.

[0022]

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a main part of a continuous jet type ink jet recording apparatus according to a first embodiment of the present invention. The continuous ejection type ink jet recording apparatus of the present embodiment
A nozzle 1 having an extremely fine circular orifice, and an ink electrode 2 for setting the potential of the ink in the nozzle 1 to the ground level, using uncharged ink particles for recording and cutting charged ink particles. A control electrode 3 having a circular opening or a slit-shaped opening concentric with the nozzle 1 and to which a control signal for controlling charging of the inkjet is applied; and a ground electrode 4 disposed in front of the control electrode 3 and grounded. A conductive knife edge 5 attached to the ground electrode 4, a deflection power supply 6, and a strong electric field perpendicular to the ink jet axis are formed between the deflection power supply 6 and the ground electrode 4 so that the charged ink particles are transferred to the ground electrode 4. Electrode 7, a conductive particle catcher 8 also serving as a detection electrode disposed at a home position in front of the ground electrode 4 and the deflection electrode 7, and a conductive particle catcher. A shield wire 9 connected to the compression spring 12 for biasing the fulcrum 11 of the nozzle 1, the nozzle 1
An adjusting screw 13 for adjusting the position of the nozzle 1 (inclination of the nozzle axis); a DC power supply DCS having a positive polarity whose output is applied to the control electrode 3 when adjusting the inkjet axis; MPU: not shown)
Switch SW1 for connecting either the control signal or the output of DC power supply DCS to control electrode 3 based on an instruction from
And a current / voltage conversion circuit CD connected to the shield wire 9
When it is configured to include a polarity discriminating circuit PD to determine the polarity of the output V ₀ which current / voltage conversion circuit CD. The output of the polarity discrimination circuit PD is processed by the MPU and displayed on a display device (not shown). Note that the DC power supply DCS is constituted by a variable DC power supply whose output voltage is adjustable.

Next, the operation of the thus-configured continuous jet type ink jet recording apparatus of the first embodiment will be described.

When adjusting the ink jet shaft (nozzle shaft), a rotating drum (not shown) around which the recording medium is wound
Is stopped, and the carriage (not shown) on which the nozzle 1 is mounted is set to the home position and stopped.

Next, ink is supplied to an ink pump (not shown).
, And is guided to the nozzle 1 through an ink tube (not shown), and the inkjet is ejected from the nozzle 1 to be kept in a steady state. Further, a vibrator (not shown) mounted on the nozzle 1 is excited at an oscillation frequency near the spontaneous particle formation frequency of the ink jet, and the ink jet ejected from the nozzle 1 is turned into particles in synchronization with the excitation of the vibrator. .

From this state, the MPU as the control means
First, the switch SW1 is switched to connect the DC power supply DCS having a positive polarity to the control electrode 3. At the time of recording, the switch SW1 is switched to connect a control signal (recorded image signal) to the control electrode 3. The DC test voltage output from the DC power supply DCS is set to a value near 1/2 of the control signal voltage (voltage for charging (turning off) the ink jet during printing).

In this state, when the ink jet shaft (nozzle shaft) is adjusted up and down by the adjusting screw 13, the ink jet passes through the knife edge 5, is cut by the knife edge 5, or collides with the knife edge 5 and scatters. Current / voltage conversion circuit CD depending on whether the collected ink is captured by the conductive particle catcher 8 or not.
Charge (charge carried by inkjet)
Changes from negative, 0 (no charge), and positive. Therefore, the output of the polarity discriminating circuit PD changes accordingly, and the position of the inkjet axis can be discriminated from the output. Hereinafter, the reason is shown in FIG.
A description will be given based on (b) and (c).

FIGS. 2A, 2B and 2C show a state in which the ink jet passes over the knife edge 5, a state where the ink jet is cut into the knife edge 5, and a collision with the tip of the knife edge 5, respectively. And show the state of scattering.
When passing over the knife edge 5 shown in FIG. 2A, the DC power supply DC of positive polarity applied to the control electrode 3 is used.
Since the negatively charged inkjet is captured by the conductive particle catcher 8 by the induction of the DC test voltage from S, negative charges flow into the current / voltage conversion circuit CD. FIG.
When the cut is performed by the knife edge 5 shown in FIG. In the case where the knife edge 5 shown in FIG. 2C collides with and scatters, the knife edge 5 is grounded, so that the collision causes the negative charge of the ink jet to disappear. Then, induced through the capacitance C _S from the deflection electrode 7 negatively charged when scattered therefrom, splashes having a positive charge is generated. When this is captured by the conductive particle catcher 8, a positive charge flows into the current / voltage conversion circuit CD.

Therefore, the position of the ink jet shaft can be determined by monitoring the polarity of the charge, that is, the output of the polarity determination circuit PD.

The optimum position of the ink jet axis is a position where a positive charge is detected. That is, at this time, as described above, the ink jet charged with the DC test voltage near 1/2 of the control voltage at the time of recording, and subjected to about 1/2 the deflection at the time of recording by the deflection electric field, causes the tip of the knife edge 5 to move. You will be glancing. Accordingly, since the deflection amount is proportional to the control voltage, the tip of the knife edge 5 is located at approximately the half point between the straight jet (on) and the deflection jet (off) during recording.

At the time of recording, whether or not the tip of the knife edge 5 is accurately at the bisecting point of the straight jet and the deflected jet is determined by the quality of the recorded image. According to the present embodiment, by changing the DC test voltage of the DC power supply DCS in the range of 0 to the control voltage at the time of recording, the tip position of the knife edge 5 can be set to an arbitrary position between the straight jet and the deflecting jet. Can be set.

By the way, in the continuous jet type ink jet recording apparatus of the first embodiment, the current / voltage conversion circuit CD must be capable of measuring a very small jet current of about 10 nA or less.

FIG. 3 is a circuit diagram showing an example of a circuit system suitable for use as the current / voltage conversion circuit CD and the synchronization signal generation circuit in the continuous jet type ink jet recording apparatus of the first embodiment shown in FIG. is there.

The current / voltage conversion circuit CD includes an integrating capacitor C and an FET (Field Effect) at the input stage.
Operational Amplifier OP1 composed of Transistor)
And a commercial AC power supply 100V (hereinafter AC
FE operating in synchronization with the frequency of 100 V)
It comprises three switches SW2, SW3 and SW4 of T.

The synchronizing signal generating circuit includes a transformer T
, A resistor R, diodes D1 and D2, a Schmitt gate SG, a preset counter PSC, delay flip-flops FF1 and FF2, an inverter IN, and an AND gate AD.

The preset counter PSC has a preset value that can be set variably (the path is not shown), so that the integration time can be changed at an integral multiple of the cycle of 100 V AC. If the integration time is lengthened, the S / N ratio naturally increases. In the present embodiment, as shown in the timing chart of FIG. 4, the integration time is set to be three times the cycle of 100 VAC.

Reset signal RESET, integration start signal H
OLD ^* (superscript * indicates an inverted signal; the same applies hereinafter) and integration end signal HOLD are each fixed to one cycle of AC100V, and when each is at “H” level, switches SW4, SW3 and SW2 are closed. West,
Open when “L” level. The sample hold signal S / H is output in synchronization with the latter half of the hold period in which the integration end signal HOLD is at the “H” level.

In the synchronizing signal generation circuit, AC100V is stepped down by a transformer T, clamped to 0V and 5V by diodes D1 and D2, and AC10V is set by a Schmitt gate SG.
TTL (Transistor-Tra) synchronized with 0V
nsistor Logic) level clock signal C
Make K. Next, based on the clock signal CK, a preset counter PSC and two flip-flops FF
1 and FF2, an inverter IN and an AND gate AD, an integration start signal HOLD shown in a timing chart.
^* , An integration end signal HOLD, a reset signal RESET, and a sample / hold signal S / H.

[0040] When the reset signal RESET is set to "H", the switch SW4 is short-circuited integrating capacitor C in the closed, the output voltage V ₀ which the integrator is reset to 0V.

After one cycle of 100 V AC, the reset signal R
When ESET becomes “L”, the switch SW4 is opened. At this time, the integration end signal HOLD is "L" (the switch SW2 is opened), since the integration start signal HOLD ^* are "H" (the switch SW3 is closed) is an operational amplifier OP1 jet current I _j is constituting the integrator And the integration is started.

Since the ink jet is charged so as to have a negative charge by the control signal applied to the control electrode 3,
The current I _{j in the} direction of the arrow flows through the integration capacitor C, and the output voltage V ₀ of the integrator becomes a positive voltage.

When a time that is an integral multiple (three times in the figure) of the AC 100 V cycle has elapsed from the start of integration, the integration end signal HO
LD is “H” (switch SW2 is closed), integration start signal H
OLD ^* becomes the "L" (the switch SW3 is opened), the jet current I _j is cut off, so far into the integrating capacitor C jets are integrated into a current I _j is the output voltage V of integrator
It is held as ₀ .

Incidentally, it is almost impossible to completely shield the space between the conductive particle catcher 8 and the integrator from noise in an actual machine. Therefore, during the integration operation, 100 V AC noise and high frequency noise generated from other peripheral electronic devices are superimposed on the output. Among them, the high-frequency noise is averaged and poses no problem because the integration time is sufficiently long, that is, one cycle or more of AC100V. Furthermore, the current / voltage conversion circuit CD of the present embodiment, since the integration time of the jet current I _j is an integer multiple of the period of AC100V, noise AC100V be averaged in the integration period, it is automatically removed Will be.

Further, the integration of the jet current I _j is completed, the integration start signal HOLD ^* changes to "L" because the switch SW3 is opened, the jet current I _j is the integrator simultaneously from the input side when it is turned off The incoming noise is also cut off. Accordingly, the operation of the polarity discriminating circuit PD is determined at this timing (in FIG. 4, the period when the sample / hold signal S / H is “H”)
, The output of the integrator is released from noise, and the jet current I _j is correctly read. For this reason, if only the integrator is sufficiently shielded, the noise is only noise generated internally, and the jet current _Ij can be measured with extremely high accuracy. As described above, an extremely high-performance current detecting means can be constituted by simple and inexpensive elements.

Now, the jet current I _j (Amper
e), integration capacitor capacitance C (Farad), integration time T (sec), output V ₀ (Vo) of integrator OP1.
lt) is V ₀ = I _j T / C. For example, I _j = 1
When 0 ^-9 A (1 nA), C = 10 ^-9 F (1000 p
F), is set to T = 0.1sec (AC100V5 _{period), V 0 = 0.1V (100mV} ) , and becomes a sufficiently practical circuit.

FIG. 5A is a circuit diagram showing an example of a polarity discriminating circuit PD suitable for use in the continuous jet type ink jet recording apparatus of the first embodiment. This polarity discriminating circuit PD
Are two comparators CP1 and CP2 and two resistors R
1 and R2, and a negative reference power source -V _S, a positive reference power source + V _S. Here, the negative reference power supply-
V _S is larger than the voltage output from the current / voltage conversion circuit CD when the ink jet passes over the knife edge 5, and the positive reference power supply + V _S indicates that the ink jet collides with the tip of the knife edge 5 and its droplets Is set to be smaller than the output voltage of the current / voltage conversion circuit CD due to the electric charge.

Also, two comparators CP1 and CP2
Operate with the sample / hold signal S / H as a strobe signal. Resistors R1 and R2 convert the outputs of comparators CP1 and CP2 to logic levels.
2-bit output voltage V from comparators CP1 and CP2
₁ and V ₂ , as shown in the table of FIG. 5B, three positions of the ink jet axis, that is, a state where the ink jet passes over the knife edge 5 (V _O <−V _S );
A state where the ink jet is cut by the knife edge 5 (−V _S <V _O = 0 <+ V _S ) and a state where the ink jet collides with the tip of the knife edge 5 (V _O > + V _S ) can be determined.

FIG. 6 is a circuit diagram showing another example of the polarity discriminating circuit PD suitable for use in the continuous jet type ink jet recording apparatus of the first embodiment. This polarity determination circuit PD
An operational amplifier OP2, a bias power supply _Vb , four resistors R3, R4, R5 and R6, and two diodes D3
And D4, and an A / D operating in synchronization with the sample and hold signal S / H
It consists of a converter ADC. Current / voltage conversion circuit C
The output voltage V _{0 of} D is level-shifted by the non-inverting amplifier (when the inkjet is cut at the knife edge 5 (V
₀ = 0), the output is set to a positive voltage capable of A / D conversion), and amplification to a level at which A / D conversion is possible is performed. In the level shift the bias power source V _b and the resistor R5, the amplification of the output voltage V ₀ is performed by the resistors R3 and R4. Diode D3, resistor R6 and diode D4
Is an element for clamping the output of the non-inverting amplifier to 0 and a voltage that does not destroy the A / D converter ADC. When the polarity discrimination circuit PD is used, the state of the inkjet axis is output as a difference between output data of the A / D converter ADC.

In the continuous jet type ink jet recording apparatus of the first embodiment, the case where the ink particles are negatively charged and a negative deflection electric field is used has been described. However, the same applies when the ink particles are positively charged and a positive deflection electric field is used. The effect of is obtained. However, in that case, the output voltage V _{0 of the} current / voltage conversion circuit CD
Has the opposite relationship to the state of the inkjet axis.

Further, in the continuous jet type ink jet recording apparatus of the first embodiment, the case where the DC power supply DCS and the switch SW1 are used when adjusting the ink jet axis has been described, but the control signal generator (not shown) is used. It is also possible to control this function by incorporating an MPU.

FIG. 7 is a view showing the structure of a continuous jet type ink jet recording apparatus according to a second embodiment of the present invention. The continuous ejection type ink jet recording apparatus of the present embodiment uses charged ink particles for recording and cuts off non-charged ink particles. The continuous ejection type ink jet recording apparatus of the first embodiment shown in FIG. The device is a DC power supply DC
The DC test voltage output from S 'is negative and set to a value near 1/2 of the control signal voltage (voltage for charging (turning on) the ink jet during recording), the position of the ink jet shaft and the charging of the ink jet The state (described in FIG. 8), the current / voltage conversion circuit CD ′ (described in FIG. 9), and the A / D converter ADC ′ (described in FIG. 10) are different.

FIGS. 8A, 8B and 8C show a state in which the ink jet passes over the knife edge 5, a state where the ink jet is cut into the knife edge 5, and a collision with the tip of the knife edge 5, respectively. And show the state of scattering.
When passing over the knife edge 5 shown in FIG. 8A, the DC power source DC of the negative polarity applied to the control electrode 3 is used.
Since the ink jet positively charged by the induction of the DC test voltage from S 'is captured by the conductive particle catcher 8, a positive charge flows into the current / voltage conversion circuit CD'. When cut by the knife edge 5 shown in FIG. 8B, 0, that is, there is no charge inflow. In the case where the knife edge 5 shown in FIG. 8C collides with the tip of the knife edge 5 and scatters, the positive edge of the ink jet is lost due to the collision because the knife edge 5 is grounded. Then, when flying from there, it is induced from the negatively charged deflection electrode 7 via the capacitance C _S , and again a droplet having a positive charge is generated. However, in this case, since the deflection voltage is 10 times or more the DC test voltage, it is extremely strongly charged, and when it is captured by the conductive particle catcher 8, it has the same polarity as that shown in FIG. Flows into the current / voltage conversion circuit CD ′.

Therefore, the position of the ink jet axis can be determined by monitoring the presence or absence and the magnitude of the positive charge.

The optimum position of the ink jet axis is a position where a large positive charge is detected. That is, at this time,
As described above, it is charged with a DC test voltage near 1/2 of the control voltage at the time of recording, and about 1 / at the time of recording by the deflection electric field.
This means that the ink jet that has been deflected by 2 grazes the tip of the knife edge 5. Therefore, since the deflection amount is proportional to the control voltage, the tip of the knife edge 5 is located at approximately the half point between the straight jet (off) and the deflection jet (on) during recording.

At the time of recording, whether or not the tip of the knife edge 5 is accurately at the bisecting point between the straight jet and the deflected jet is determined by the quality of the recorded image. According to the present embodiment, the DC test voltage output from the DC power supply DCS ′ is made variable in the range of 0 to the control voltage at the time of recording, so that the tip position of the knife edge 5 is set between the straight jet and the deflecting jet. It can be set at any position.

FIG. 9 is a circuit diagram showing an example of a current / voltage conversion circuit CD 'suitable for use in the continuous ejection type ink jet recording apparatus of the second embodiment. In the continuous ejection type ink jet recording apparatus of this embodiment, only positive charges of 0 and 2 stages are detected. Therefore, the output of the integrator is
It becomes negative voltage. Therefore, in this embodiment, in order to enable input to the A / D converter ADC ′ at the subsequent stage, the operational amplifier OP3
It is making the output voltage V ₀ through inverting amplifier made up of two resistors R7 and R8. Amplification rate R8 / R7
Is determined in consideration of the output level of the integrator and the allowable input level of the A / D converter ADC ′.

FIG. 10 (a) shows an AD which is suitable for use in the continuous jet type ink jet recording apparatus of the second embodiment.
FIG. 14 is a circuit diagram illustrating an example of a converter ADC ′. In the continuous jet type ink jet recording apparatus of the present embodiment, the same polarity (positive)
Is detected, it is convenient to use the A / D converter ADC 'to determine the position of the inkjet axis. FIG. 10A shows an example of a simplified A / D converter composed of two comparators CP3 and CP4, two reference power supplies + V _S ^' , + V _S ^" and two resistors R9 and R10. , The reference power supply + V _S ^′ is smaller than the output of the current / voltage conversion circuit CD ′ when the ink jet passes through the knife edge 5, and the reference power supply + V _S ^″ is the current / voltage when the jet collides with the tip of the knife edge 5.
It is set smaller than the output of the voltage conversion circuit CD '.
Note that + V _S ^' <+ V _S ^" .

Further, two comparators CP3 and CP4
Operate with the sample / hold signal S / H as the strobe signal. Resistors R9 and R10 convert the outputs of comparators CP3 and CP4 to logic levels. 2-bit output voltage V ₃ from comparators CP3 and CP4
And from V _4, as shown in the table of FIG. 10 (b), 3 one position of the ink jet axis, i.e., the state in which the ink jet passes through the knife-edge ^{_{5 (+ V S '<V}} 0 <+
V _S ^") and a state in which the ink jet is cut by a knife edge 5 (V ₀ <a + V _S ^'), a state in which the ink jet impinges on the tip of the knife edge _{5 (V 0> + V S} ")
Can be determined.

It is needless to say that a commercially available A / D converter can be used instead of the A / D converter shown in FIG.

In the second embodiment, the case where the ink particles are positively charged and a negative deflection electric field is used has been described. However, the same effect can be obtained even if the ink particles are negatively charged and a positive deflection electric field is used. Can be However, in that case,
The inverting amplifier of the voltage conversion circuit CD 'needs to be a non-inverting amplifier.

In the first and second embodiments, two
Although the description has been given of the continuous ejection type ink jet recording apparatus of the value control method, it is needless to say that the present invention can be similarly applied to the continuous ejection type ink jet recording apparatus of the analog deflection method.

[0063]

As described above, according to the present invention,
A state in which the ink particles are deflected to a predetermined position by the DC test voltage, and the deflected ink particles pass through the separating means;
High accuracy and easy adjustment of the ink jet axis is possible by making it possible to easily detect the state of being cut by the separating means and the state of colliding with the tip of the separating means by the second charging means and the charge detecting means. Has the effect of becoming

Further, by making the DC test voltage variable, it is possible to arbitrarily adjust the positional relationship between the ink jet shaft and the separating means.

Further, by configuring the charge detecting means to include an integrator which operates in synchronization with AC100V,
There is an effect that it is possible to detect the inkjet axis with high reliability.

Further, since the charging means and the second charging means charge the ink particles with the opposite polarities or the same polarity with greatly different levels, the ink jet shaft can be adjusted easily and inexpensively with high precision and ease. There is an effect that a continuous ejection type ink jet recording apparatus which can be realized can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a continuous jet type ink jet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a principle of determining an inkjet axis in a continuous ejection type inkjet recording apparatus according to a first embodiment.

FIG. 3 is a circuit diagram showing an example of a current / voltage conversion circuit in FIG.

FIG. 4 is a timing chart illustrating an operation of the current / voltage conversion circuit of FIG. 3;

FIG. 5 is a circuit diagram illustrating an example of a polarity determination circuit in FIG. 1;

FIG. 6 is a circuit diagram showing another example of the polarity discrimination circuit in FIG. 1;

FIG. 7 is a configuration diagram illustrating a continuous ejection type ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a principle of determining an inkjet axis in a continuous ejection type inkjet recording apparatus according to a second embodiment.

FIG. 9 is a circuit diagram illustrating an example of a current / voltage conversion circuit in FIG. 7;

FIG. 10 is a circuit diagram illustrating an example of an A / D converter in FIG. 7;

FIG. 11 is a configuration diagram showing an example of a conventional continuous jet type ink jet recording apparatus.

FIG. 12 is a diagram illustrating an example of a nozzle adjustment mechanism in FIG. 11;

[Explanation of symbols]

 Reference Signs List 1 nozzle 2 ink electrode 3 control electrode 4 ground electrode 5 knife edge 6 deflection power supply 7 deflection electrode 8 conductive particle catcher 9 shield wire 11 fulcrum 12 compression spring 13 adjustment screw AD AND gate ADC 'A / D converter C integration capacitor CD Current / voltage conversion circuit CP1 to CP4 Comparator D1 to D4 Diode DCS, DCS 'DC power supply FF1, FF2 Flip-flop IN Inverter OP1 to OP3 Operational amplifier PD Polarity determination circuit PSC Preset counter R, R1 to R10 Resistance SG Schmitt gate SW1 SW4 switch

Claims (6)

(57) [Claims] 1. A particle forming means for dividing an ink jet into a series of ink particle rows, a first charging means for charging ink particles formed by the particle forming means, and a deflection electric field orthogonal to an ink jet axis. Deflecting means for deflecting charged ink particles, separating means for cutting ink particles deflected by the deflecting means and passing undeflected ink particles, and charging ink particles colliding with and scattering at the tip of the separating means A second charging unit, a charge detection unit that captures the ink particles that have passed through the separation unit and the ink particles that collided with the tip of the separation unit and scattered, and detects the charge thereof. Inkjet axis adjustment state determining means for determining whether or not the inkjet axis can be adjusted based on the electric charge; Continuous jet type ink jet recording apparatus characterized by comprising a jet axis adjusting means for adjusting the positional relationship between the separating means. 2. A control signal generating means for generating a control voltage according to a recording signal; a test voltage generating means for generating a DC test voltage between 0 and the control voltage; A control electrode for charging the ink particles in accordance with the applied voltage, and switch means for connecting any one of the output of the control signal generating means and the output of the test voltage generating means to the control electrode. The continuous ejection type ink jet recording apparatus according to claim 1. 3. A control signal generating means for generating a control voltage in accordance with a recording signal and a DC test voltage between 0 and the control voltage, wherein the first charging means outputs a control voltage in accordance with a recording signal. 2. A continuous jet type ink jet recording apparatus according to claim 1, further comprising a control electrode connected to said ink supply unit for charging said ink particles in accordance with an output of said control signal generating means. 4. The continuous ink jet recording apparatus according to claim 1, wherein said second charging means is included in said deflecting means. 5. The method according to claim 1, wherein the first charging unit and the second charging unit charge the ink particles with opposite polarities, and the inkjet axis adjustment state determining unit is a charge detecting unit including a polarity determining unit. The continuous jet type ink jet recording apparatus according to claim 1, wherein 6. A charge device according to claim 1, wherein said first charging means and said second charging means charge ink particles to have the same polarity and different levels, and said inkjet axis adjustment state determining means includes an analog / digital conversion means. 2. The continuous jet type ink jet recording apparatus according to claim 1, comprising a detection unit.