JPS604787B2 - Inkjet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording device, and more particularly, to
The present invention relates to a recording device using an electric field ejection type inkjet generator that can be used as a recording head in an image recording device such as an X-Y plotter used for automatic drafting.

Generally, in a line recording device such as an x-y plotter,
A so-called contact type recording device such as a hollow pen or a ballpoint pen is used as the recording head.

However, these contact type recording tools have poor durability and must be replaced frequently, making it difficult to perform high-speed recording and thin line recording, and the recording line density may be uneven.
It had many drawbacks, such as the tendency to generate noise. For this reason, in recent years, attempts have been made to apply so-called inkjet generators that eject ink in an ink tank from nozzles with minute diameters to recording heads of image recording devices such as X-Y plotters.

Various devices have been proposed as this type of inkjet generating device, but when using it for recording with a line recording device, continuity of the line and ON/OFF of the jet flow are important.
Considering the responsiveness, etc., an open field jet inkjet generator is most suitable. This Seriba injection type inkjet generator guides ink from an ink tank to a nozzle, and in a stationary state applies a minute pressure on the ink to the extent that the ink forms a meniscus at the tip of the nozzle, and connects the ink to a conductive nozzle or ink and nozzle. By applying a high electric field between the nozzle and an accelerating electrode installed in front of the nozzle, ink is drawn out from the nozzle and ejected as a jet stream. By using this type of inkjet generator, many of the disadvantages of conventional contact-type recording devices can be solved, but because it is a non-contact type, it has the following characteristics not found in conventional contact-type recording devices: There are disadvantages such as.

In other words, when this type of inkjet generator is applied to a line recording device such as an Therefore, if the amount of ejected ink is constant, the width and density of the image line will change depending on the recording speed, which is particularly inconvenient for automatic drafting and the like. In addition, the amount of ink ejected is affected by the pressure acting on the nozzle inlet, that is, the sum of the pressure acting on the ink surface (e.g. air pressure) and the hydrostatic pressure of the ink from the ink surface to the nozzle inlet. When recording, the amount of ink ejected fluctuates due to the decrease in the amount of ink in the ink tank, and the jet ON characteristics deteriorate significantly. Therefore, all the ink in the ink tank cannot be used, and the amount of ink ejected is not affected. Since it can only be used for a limited amount of time, it has the disadvantage that the recording time with one ink filling is very short. Furthermore, there is a problem in that when the conditions around the inkjet generating device change, the physical properties of the ink change, and the amount of ink ejected fluctuates. Furthermore, with inkjet generators, the ink surface inside the ink tank shakes due to acceleration during movement, causing maintenance problems such as ink spilling out of the ink tank, and the amount of ink jetted is proportional to hydrostatic pressure. Therefore, when the ink surface fluctuates, the amount of ejected ink changes under the influence of hydrostatic pressure even when the recording speed is constant, resulting in a problem that the quality of uniform lines is degraded, causing unevenness in the line width. As a result of various studies to solve this problem, the present invention has discovered that when the applied voltage is constant, the pressure acting on the ink and the amount of ink ejected are in a proportional relationship. When the amount of ink jetted is changed by appropriately changing the applied pressure,
When drawing a diagram by taking the logarithm of the amount of ejected ink and the recorded line width, we found that there is a linear relationship, and from this,
If the physical properties of the ink, the shape of the nozzle, etc. are constant, the relative relationship between the amount of ink jetted, the pressure acting on the ink, the recording line width, and the recording speed can be determined, so the pressure can be converted into the recording speed. This method was developed based on the finding that by controlling the amount of ink ejected in accordance with the recording speed, it is possible to obtain a constant recording line width at all times.

The main object of the present invention is to provide an inkjet recording device that is equipped with a pressure control means that controls the pressure acting on the surface of ink in accordance with the recording speed, and is capable of drawing lines of a constant width regardless of the recording speed. It is also an object of the present invention to provide an image recording device, especially an X-Y plotter, equipped with such an inkjet recording device;
The purpose is to provide a specific control circuit that associates the servo control mechanism of the plotter with the pressure control mechanism,
A further object of the present invention is to provide a specific device associated with a pressure control mechanism when the above-described inkjet generating device is used in a recording head of an X-Y plotter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1 showing an X-Y plotter according to the present invention, rails 3 and 4 are fixedly installed on both sides of the upper surface of a main body 2, and a rack is cut into the rail 3.

The x-movement girder 5, which extends over the pair of rails 3 and 4 and moves in the X direction, is fixed on support stands 6 and 7 that are slidable on the rails 3 and 4. An x-servo motor 8 is installed inside the support base 6, and drives a pinion gear (not shown) that engages with the rack of the rail 3 via an appropriate transmission mechanism to move in the x direction. . x A Y-direction rail 9 is installed parallel to the movable girder 5, and this
A rack is also cut into the one-way rail 9. A slider 10 is slidably provided on the Y-direction rail 9, and a Y-servo motor 11 is installed inside the slider 10, and a pinion gear ( (not shown) to move in one Y direction. In the mover 1, an inkjet generator 13 is installed by the head main body 12, which moves integrally with the mover 10, injects ink by a control mechanism described later, and performs image recording by an x-Y servo mechanism. It is designed to do this. Inkjet generator 1
3 includes a flexible air pipe '8 that sends compressed air to the ink tank 14 and a high-voltage cable 19 from a high-voltage power source.
These air piping 18 and high voltage cable 19 have a sufficient length so as not to cause any inconvenience to the drawing operation, and are connected to a control section, a compression pump, etc. inside the main body 2.

The upper surface of the main body 2 is a drawing board 20 that supports a recording material (paper, film, etc.) 21 while maintaining its flatness.

The X-Y plotter device having such a configuration is designed to plot by controlling the rotation angles of the X and Y servo motors 8 and 11 in response to a plotting pattern signal output from a computer or the like. There is.

Further, as shown in FIGS. 2 and 3, the inkjet generator 13 includes an ink tank 14 for storing ink 17, a nozzle 15 attached to the ink tank for guiding ink to the outside, and a nozzle 15 attached to the ink tank for guiding the ink to the outside. It is composed of a counter electrode 16 placed close to each other.

As shown in FIGS. 2c and 3b, two positioning pins 61 are fixed to the outer periphery of the ink tank, facing each other. inserted.

At the bottom of the ink tank 14 is a metal nozzle fixing cylinder 62.
The nozzle guide ring 63 made of insulating material is fixed to the tip of the nozzle guide ring 63, and the center of the guide ring 63 is attached to the center of the tip of the nozzle fixing tube 62 by soldering or the like. A metal nozzle 15 passes through it (Fig. 3e). An outer cylinder 64 made of an insulating material, for example, a synthetic resin such as formaldehyde polymer, is attached to surround the nozzle fixing cylinder 62, and an annular counter electrode 16 is attached to the tip of the outer cylinder 64. The seal between the ink tank 14 and the nozzle fixing tube 62 is a ○ ring 65.
This is done by The head body 12 is an upper body 12a.
and a lower body 12b, and an annular hole 66 having a diameter slightly larger than the outer diameter of the ink tank 14 is provided in the center of the upper body 12a, and an opposing notch 67 is provided around the annular hole 66. (Figure 3a).

As shown in FIGS. 3c and 3d, in the center of the lower body 12b, annular grooves 68 and 69 with a diameter slightly larger than the outer diameter of the ink tank 14 are provided facing each other from above and below. communicates the annular grooves 68 and 69. An annular hole 70 having a diameter slightly larger than the outer diameter of the outer cylinder 64 is provided,
Two opposing notch grooves 71 are provided around the upper annular groove 68, and a shallow groove with a larger diameter than the groove 68 is provided, and an ink tank fixing ring 72 is provided within this shallow groove.
is installed. This fixing ring 72 has two
The fixed ring 72 is always given a rotational force in one direction because a spring 74 is fixed to one pin 73, but the other pin 73 is fixed to the fixed ring 72.
Since the tip of the release button 75 is engaged with the release button 75, the release button 75 is held in a predetermined position. The fixing ring 72 is provided with a notch 76 on its inner periphery through which the positioning pin 61 of the ink tank 14 can pass, and a slope 77 connected to the notch 76 . A high voltage electrode ring 78 is disposed at the bottom of the upper annular groove 68, and three high voltage electrode pieces 79 are soldered to the upper side thereof. This high-voltage electrode piece 79 contacts the flange portion of the nozzle fixing cylinder 62 when the ink tank is installed, and has one end connected to the connector 801 and the other end to the high-voltage electrode ring 78, and is wired through the wiring groove of the head body. A high voltage from line 81 is applied to nozzle 15 . A counter electrode ring 82 is disposed within the lower annular groove 69, and three counter electrode pieces 83 are soldered downward around the inner periphery of the counter electrode ring 82. This counter electrode twill piece 83 has elasticity, and when the ink tank is attached, its tip contacts the counter electrode 16, and one end is connected to the connector 801 and the other end to the counter electrode ring 82, and the wiring is routed through the wiring groove of the head body. A voltage (of opposite polarity to the voltage applied to the nozzle) from the ground wire 84 is applied to the counter electrode 16 . The counter electrode ring 82 and the counter electrode piece 83 are surrounded by the protection tube 60'. When the ink tank 14 is inserted into the annular hole 66 by aligning the positioning pin 61 with the notch 67 and the notch groove 71 of the head body 12, the positioning pin 61 first contacts the inclined part 77 of the ink tank fixing ring 72. (4th
Figure a), when you press down further, the ink tank fixing ring 7
2 rotates in the direction of the arrow shown in FIG. 3d and FIG.
The ink tank fixing ring 72 enters the notched groove 71, and the ink tank fixing ring 72 returns to its original position by the action of the spring 74 (see Fig. 4c).
), the ink tank 14 is installed as shown in FIGS. 2b and 2c.

A lid 86 with a fitting 85 attached to the top of the ink tank
is detachably attached, and the ink tank 14 is connected to the piping 18 through a joint 85.

The ink tank can be attached or removed by pressing the release button 75, which pushes the pin 73 that engages with the release button 75 and rotates the ink tank fixing ring 72 in the direction of the arrow.
Since the ink tank moves to the position of the notch groove 71, this can be done by pulling up the ink tank in this state.
A jet observation magnifying glass 87 is provided on the head body 12 so that the state of the jet emitted from the nozzle 15 can be directly observed.
is installed.

This optical system loupe consisting of a reflecting mirror 87a, an objective, and an eyepiece is detachably held on the head body 12 by a loupe support member 89 having a fixing pin 88. The head body 12 has a hole 9 that mates with the fixing pin 88.
The jet observation magnifying glass 87 is positioned by inserting the fixing pin 88 into the hole 91 while aligning the magnifying glass tube with this recess 91. It will be installed. The counter electrode 16 has
As shown in FIGS. 3e and 3f, a jet observation slit 92 is provided so as not to disturb the symmetry of the lightning field. FIG. 5 shows the results of examining the relationship between the pressure acting on the ink surface and the amount of ink ejected using the inkjet generator configured as described above.

This is done by applying a constant voltage between the nozzle 15 and the counter electrode 16 as an inkjet switching voltage to the inkjet generator for a certain period of time, and changing the pressure acting on the ink surface appropriately to change the amount of ink ejected every second. It is plotted as . From this figure, it can be seen that the amount of injected ink is proportional to the pressure over a fairly wide range. FIG. 6 shows the relationship between the amount of ink jetted and the line width of the recorded image. This involves wrapping the recording material around a drum that rotates at a constant speed, moving the inkjet generator at a constant speed in the direction of the rotation axis of the drum, and feeding compressed air into the ink tank to reduce the pressure. The amount of ejected ink is changed by changing it appropriately, and the state of change in the recorded image line width at that time is plotted. From this figure, it is understood that the amount of ejected ink and the line width have a linear relationship on the logarithmic scale. Furthermore, this experiment revealed that the slope of the straight line in this figure is determined by other factors such as the physical properties of the ink. Therefore, by accurately controlling the pressure acting on the ink surface in accordance with the recording speed, it is possible to obtain an amount of ejected ink corresponding to the recording speed.
It is understood that recorded lines of constant width can always be obtained.

For this reason, the inkjet recording apparatus of the present invention is equipped with means for controlling the amount of injected ink according to the recording speed.
This is associated with the X-Y control mechanism of the X-Y plotter.

The relationship between the X-Y control mechanism and the pressure control means of the inkjet recording apparatus will be explained below. Figure 7 shows
It is a block diagram of the x-Y servo control mechanism.

Normally, in an X-Y plotter, it is necessary to control the position of the movable element 10 (recording head) extremely accurately, and therefore a negative feedback method is used for position control.

Further, in the control mechanism shown in the figure, the target position signal is a digital signal such as the number of pulses, and this is an example of a case where an analog servo motor is used as the servo motor. The X-Y servo control is performed independently in the X and Y directions and is substantially the same, so the X-control system will be described below. When a drawing signal is outputted from a computer (not shown) and inputted to the interface 22 of the servo control mechanism, an X-target position signal is output as a digital signal, and a comparator 23 converts it into an x-position signal. After being compared and converted into an analog signal by a digital-to-analog converter (D/A converter) 24, it is amplified by an X-servo amplifier 25, and the X-servo motor 8 is rotated by an angle corresponding to the output signal of the comparator 23. . At this time, the output of X-servo motor 8 is
The signal of the speed detector 26 is detected by the speed detector 26 and the x-position detector 27, and the signal of the speed detector 26 is
- Feedback to the front stage of the servo amplifier 25. Further, the output of the position detector 27 is converted into a digital signal by an analog-to-digital converter (A/D converter) 29, and then
The signal is input to a comparator 23, and the position is controlled while being compared with the target position signal. In this case, the rotation speed is detected by a speed meter such as a tacho generator attached to the servo motor shaft, and the position detection is performed by a solver or the like. In addition to such a servo motor control mechanism, the X-Y plotter apparatus of the present invention includes a pressure control mechanism for controlling the amount of ink ejected by the inkjet generator according to the recording speed.

It detects the rotational speed of each of the X and Y servo motors as the output of the servo motor, and sends it to the speed signal vx,
This signal is used to control the pressure acting on the ink tank of the inkjet generator. FIG. 8 shows a block diagram of this pressure control mechanism. In the interface 31 of the pressure control mechanism,
There is a recording speed signal v production circuit as shown in FIG.
When the speed signal vx and the Y-speed signal vy are input, they are squared by squaring circuits 32 and 33, respectively, and v
x2 + vy2 is taken, and the square root circuit 35 generates the recording speed signal v
= ノ v x 20 v〆 is created.

This recording speed signal v is sent from the interface 31 to an analog comparator 36 consisting of a differential amplifier with a voltage gain of 1, etc., and the output (analog signal) of the pressure sensor 38 that detects the air pressure of the compression pump 37 is sent to the feedback amplifier 39. The amplified signal is compared with the amplified signal, and the comparison signal is inputted to four controllers. The controller 40 is composed of a window comparator, a pulse converter, etc., and only when the absolute value of the input error signal (comparison signal) is larger than the window width (±VR), it outputs a clock pulse to the next stage pulse motor drive circuit 41. Set to send synchronized signals CW and CCW. Signal CW
is issued when the error signal is greater than 10 VR, and the air compression system 42 acts to increase the pressure, and the signal CCW is issued when the error signal is less than -VR, and the air compression system 42 acts to increase the pressure.
acts in the direction of lowering the pressure, and the error signal is VR and -VR
If the value is between, the controller 40 will not issue a signal. The pulse motor drive circuit 41 is a circuit for converting the above-mentioned signals CW and CCW into signals for driving the pulse motor 43 and amplifying the signals. When the input signal is CW, the pulse motor 43 is rotated in the normal direction to perform compression. Increase the air pressure of the pump 37 and
In CW, it is reversed.

The air pressure inside the compression pump 37 is detected by the pressure sensor 38, amplified by the feedback amplifier 39, and then sent to the comparator 3 as described above.
6, and pressure control is performed while being compared with the recording speed signal v.

For example, when the value of the recording speed signal v increases, the output of the pressure sensor 38 at that moment is smaller than the speed signal v, the comparator 36 outputs an error signal, and the controller 40 outputs a signal C.
W is released and acts to increase the pressure as described above.

In addition to the X-Y servo control signal, the drawing signal output from the computer etc. includes an inkjet jetting control signal Sd, and the inkjet ON-- It is sent directly to the interface 31 of the pressure control mechanism as an OFF signal.

In an X-Y plotter using a conventional contact writing instrument, this inkjet ON-OFF signal is
This signal corresponds to the "p-Downm" signal, and is input to the high-voltage pulse generator 501 only when necessary, and applies a switching high voltage to the nozzle 15 of the inkjet generator 13 to eject a jet. , velocity signals vx, vy, v, pressure P acting on the ink, voltage Vj applied to the nozzle, recording line width, and inkjet ejection control signal (printing command) Sd are shown in a time chart in FIG.

That is, when a plotting signal is input, the X-Y servo control mechanism operates to move the mover (recording head) 10 to a predetermined position, and when the plotting command Sd is input, "the inkjet generator 13 is set at a recording speed v". Therefore, the recording line width is constant regardless of the recording speed v, and the ON/OFF of the jet is also determined by the plotting command Sd.
It follows extremely well. The inkjet can be turned on and off at high speed by, for example, applying a bias voltage between the nozzle and the accelerating electrode and applying a switching voltage in accordance with a plotting signal. In Figure 11, a constant pressure (atmospheric pressure) is applied to the ink surface in the ink tank, and a bias voltage of 800N is applied to the Kasumi field type inkjet generator by the bias power supply 30 to form a meniscus at the nozzle tip. In addition, when the high voltage pulse generator 50 also uses 1000V as the switching voltage and bias voltage,
This figure schematically shows the state of inkjet jetting. In this case, the response to the switching voltage ON' for starting injection is 1 to 3 sec. The response to the switching voltage OFF for stopping injection is 0.5 sec. It was below. Therefore, even compared to the responsiveness to drawing signals of a contact type (Ben UpDown type) using a secondary pen, for example, the ON-OFF characteristics of the inkjet flow are extremely good (more than one order of magnitude farther), and × - It can be seen that it can be used satisfactorily for Y plotters and the like. Next, a specific mechanism of the air compression system of the inkjet generator in the above-described x-y plotter device will be explained.

As shown in FIG. 12, the air compression system 42 includes a pulse motor 43 that operates in response to the output signal from the pulse motor drive circuit 41 described above, and converts the rotation angle of the pulse motor 43 into a corresponding linear displacement amount. A converter 46 includes a cam 44 installed on the rotating shaft of the pulse motor and a piston 45 that follows the cam 44, and a piston 48 fixed to one end of the piston rod 45 and sliding inside a cylinder 47. , a diaphragm pneumatic pump 37 consisting of a diaphragm 49, etc., with one end fixed to the piston and the other end fixed inside the cylinder; and a pressure pump 37 that is attached to the cylinder 47 and detects the air pressure inside the cylinder 47 and converts it into an electric signal. It is composed of a sensor 38, a flexible air pipe 18 for sending compressed air in the cylinder to the ink tank 14 of the inkjet generator 13, and the like.

As described above, the air compression system 42 configured as described above detects the air pressure in the cylinder by the pressure sensor 38 and converts it into voltage, the voltage is amplified by the feedback amplifier 39, and an air-failure signal is sent to the analog comparator 36. This is a negative feedback method that compares the recording speed signal converted by the same machine.

In this pneumatic control mechanism, as shown in Fig. 5, the pressure control range necessary to obtain the amount of ejected ink corresponding to the recording speed is practically 40 to 60 Aq, so the movement of the piston is sufficient. Volume change in the cylinder due to 8
V is sufficiently satisfied if it is 1'10 or less of the total volume V.

Therefore, to explain the compression process, suppose the cylinder volume before compression is V, the pressure is P, and the cylinder volume after compression (piston stroke 61) is V2, and the pressure is P2, then the state of the air in the cylinder. Since the change is thermodynamically polytropic (a change intermediate between isothermal change and adiabatic change), P. V. The relationship k=P2V2k (1<k<1-4) holds true. Here, V, - V2 = 6V (6V《V,
) and solve for P2, we get P2niP・(1-6V
/VI)-k mother PIX (10K, 6V/V,),
If the pressure change in the cylinder is 6P = P2 - P, then 6 pine K damage / 6 V. Also, if the effective pressure receiving area of the diaphragm 49 is S, then 6
V=S·61, therefore, 6×K is 1,61, and since KSP,/V is a constant, the cylinder pressure change 6P is approximately linearly proportional to the piston stroke 61.

Further, the detected pressure of the pressure sensor 38 and the output voltage are linear, and the shape of the cam 44 of the converter 46 is set so that the rotation angle of the pulse motor 43 and the piston stroke are linear, so that the The compression system 42 is composed of all linear components and is extremely easy to control.
In addition, the entire system of this air pressure control device is installed outside the moving mechanism, and only pressure-controlled air is sent to the ink tank 1411 through the air piping 18, so the head main body 12 in which the inkjet generator is installed is extremely In addition to being smaller and lighter, it is not affected by disturbances caused by the movement of the recording head, allowing accurate control.

In particular, pressure sensors are easily affected by vibrations.
As shown in FIG. 13, the cylinder may be connected with a flexible pipe 51 and further mounted on a vibration absorbing table 52 made of rubber or the like to absorb vibrations to prevent disturbances to the control system due to vibrations, etc. good. Furthermore, the inner diameter of the flexible air piping 18 of the air compression system 42 is made as small as possible (1 to 2 diameters) so as not to affect the air pressure control system.

That is, when the inner diameter is large, the natural vibration of the air column, which is determined by the distance between the diaphragm surface inside the cylinder and the ink surface (about 3 to 5 m in the case of a large drawing machine), hits the ink surface as shown by the solid line b in Figure 14. Due to the pressure that is applied, the air pressure displacement within the cylinder as shown by the solid line a in FIG. 14 is not accurately transmitted to the ink surface within the ink tank, making high-speed control impossible. Therefore, by making the inner diameter small, the influence of natural vibration is kept extremely small compared to the pressure displacement of pneumatic control. In this case, as shown in FIG. 15, if a needle valve 53 is inserted between the cylinder 37 and the piping joint 54 to adjust the fluid resistance by manually adjusting the air passage cross-sectional area, the ink surface The applied pressure waveform is as shown by the solid line c in FIG. 14, and no vibration occurs. This takes advantage of the fact that the propagation waveform of air pressure, as mentioned above, is sensitively affected by changes in fluid resistance in piping, etc., and by adjusting the needle valve appropriately, it is possible to eliminate the operation of inconvenient pressure propagation. . The air whose pressure has been controlled by the air pressure control device as described above is transferred to the inkjet generator 13 shown in FIG. 2 through a flexible air pipe 18.
sent to.

The inkjet recording device of the present invention and the X-Y plotter equipped with this inkjet recording device have the above-mentioned configuration and functions, but furthermore, regarding the control of the ink jetting amount and each part mechanism of the inkjet recording device, By providing some additional or improved devices or circuits, etc., which will be described later, it is possible to further expand the range of applications and improve the accuracy. In the x-Y plotter of the present invention, the pressure applied to the ink is controlled in response to the speed signal as described above.
By changing the reference pressure level of this pressure control, it is also possible to record various line widths with a single nozzle. Specifically, as shown in FIGS. 16 and 17,
This is achieved by varying the amplification gain of either the speed signal v or the feedback pressure signal before inputting the signal to the comparator 36. That is, in FIG. 16,
The speed signal v is input to the positive phase amplifier 55. The positive phase amplifier 55 has feedback resistors Rx, , Rx2 each having a different resistance value.
, Rx3, and switches SW, ,SW2, SW
3 to be used selectively. In this case, the voltage gain of the positive phase amplifier is given by (R+Ryanagi)/2R, and the voltage gain is determined by appropriately setting Rx, , Rx2, and Rx3. Above switches SW,,SW
2, SW3 is selected by the gain selector 56, which operates an appropriate switch in response to an external signal Swd specifying the box width. For example, if a thick drawing line is required, the switch is selected so that the gain of the positive-phase amplifier becomes large. Then, the speed signal v is amplified from the actual speed and input to the comparator, and as a result, the pressure is controlled to increase accordingly. When using a method in which the speed signal v is made variable and inputted to the comparator 36, the actual recording speed is changed by the print width designation signal Swd, and the speed signal is further input to the gain selector 5.
It is also possible to change the magnification by 6 and input it to the comparator 36.

That is, in the method shown in FIG. 16, the actual recording speed is not changed, but the gain of the speed signal is changed by the amplifier 55 and inputted to the comparator. Therefore, a certain speed signal v
, when a thick drawing line is requested, the signal v2 input to the comparator 36 has the relationship [v, x v2]. The actual recording speed at this time is assumed to be V. Next, try lowering the actual recording speed to V2 (V2<V,). At this time, the recording speed signal is v2, which is converted into v,
Assume that the data is returned to the original state and inputted to the comparator 36. in this case,
Since (V2<V,), the drawing line width becomes thick as described above. Based on the above, we get the following table. FIG. 17 shows an example in which the voltage gain of the amplifier 57 that amplifies the power supply pressure signal is made variable so that the line width can be changed.The gain selector 56, switch, resistor, etc. are the same as in FIG. They are the same, but the difference is that when a thick drawing line is required, the voltage gain is made smaller.

In addition, as shown in FIG. 18, in addition to the compression pump for controlling air pressure, an auxiliary pump 59 whose cylinder internal volume is controlled by another pulse motor 58 is installed in parallel with the compression pump 37. connected by a pipe 93,
It can also be activated by a line width conversion signal.

In this way, when the line width designation signal shown in the above two examples is input, the auxiliary pump converts the air pressure in steps, and the air pressure control pump 37 changes the line width depending on the recording speed. It can be used only for the original purpose of controlling the amount of ink to be ejected so as not to cause damage, and each air pressure can be controlled accurately and easily.
This auxiliary pump 59 is connected to the cylinder 47 of the pneumatically controlled pump 37 by a pipe 93, and the piston 9
4 within the cylinder 95 has a rack cut therein, and is directly actuated by a pinion 97 provided on the rotating shaft of the pulse motor 58. In the above example, Rx. ,R
Although resistors with different resistance values such as x2 and Rx3 are connected in parallel and selected for use, this can also be replaced with a single variable resistor, and in this way, the line width can be made continuous. can be changed. Further, the value creation control method of the pressure control mechanism used in the inkjet recording apparatus of the present invention has a configuration as shown in FIG. 8, but in such a negative feedback control method, the pressure acting on the ink, Since the pressure to be controlled is at a very low level (usually 0 to 100 Aq), a highly sensitive pressure sensor is required.

For this reason, sensors using semiconductor strain gauges are used, but the temperature characteristics of this pressure sensor are very poor, and the output voltage is low (about several tens of volts), so feedback amplifiers with high amplification are required. This temperature characteristic is also a major issue. Therefore, creating a negative feedback loop requires advanced technology and expensive components. On the other hand, X-Y
Plotter devices require relatively short operating time each time (
For example, in the case of automatic drafting, it is sufficient that the device operates normally during this period (several minutes to several IQ minutes), and the temperature change during this period is usually several degrees Celsius.
It is thought that the following is true.

Therefore, considering this fact in the actual negative feedback loop, it is possible to relatively easily prevent disturbances caused by temperature changes, etc., as described below. FIG. 19 is a block diagram illustrating the circuit system. In the control circuit of FIG.

An input gate 98 is inserted before the differential amplifier 36, the feedback amplifier 9 in the feedback loop is a differential amplifier 39', an offset adjuster 99 is connected to the negative input side, and the differential amplifier 3
A feedback gate 100 is inserted between the input gate 98 and the analog comparator 36, and a zero point detector 101 is connected to the output side of the differential amplifier 39'. The output of the former is supplied as the slit control signal of the latter. The output of the differential amplifier 39' in this control circuit is set to be zero when the apparatus is stopped. Incidentally, in order to confirm that the output of the differential amplifier 39' is zero, a pilot lamp or the like is activated by the zero point detector 101 or the like to display the result. Next, to explain the operation of this circuit, when the device is stopped, even though the output of the air compressor, which is the controlled object 102, is zero, the output detector (pressure sensor) 1
03 and the differential amplifier 39',
If the differential scale amplifier output is not zero, the zero point detector 101 detects this and outputs a signal that connects the input gate 98 and the feedback gate 100 to the state shown in the figure, disconnects the input (target value) and the feedback loop, and sets the OFH. At the same time as rubbing, the operator is informed of the condition using the pilot lamp or the like.

Note that in this state, the pressure control system is stopped. Upon receiving this notification, the operator adjusts the negative input of the differential amplifier 39' using the offset adjuster 99 to make the output of the differential amplifier 39' zero, and the zero point detector 101 detects this output level and inputs it. ○ gate and period gate
N and are connected to the input (target value) and differential amplifier 39', respectively, and at the same time inform the operator of the status using a pilot or the like. At this point, the control system is connected as shown in FIG. 8 and enters a normal operating state. In this way, even if the output of the controlled object is zero before operation, and there is a drift in the output detector 103 and the differential amplifier 39' and the output of the differential amplifier is not zero, the feedback signal can be easily made zero, Accurate control possible. Fig. 20 shows a case where the method shown in Fig. 19 is applied to the pressure control system shown in Fig. 8, in which the input gate and the feedback gate are operated by digital signals (TTL level) using analog switches 104 and 105, and offset The regulator 99 consists of a voltage follower with a manual potentiometer 106 connected to its positive input terminal, and the zero point detector 101 consists of a window comparator with a window width of volts (sufficiently small compared to the required control accuracy). There is.

Next, the operation will be explained in conjunction with FIGS. 8 and 19. First, during the operation preparation stage of the x-Y plotter, the cylinder of the air compressor is communicated with the atmosphere through a normally open solenoid valve (not shown). Therefore, the input to the pressure sensor 38 is kept at zero. When the preparation of the ×-Y plotter is completed, the solenoid valve is closed and the inside of the cylinder becomes airtight, and if the output of the differential amplifier 39' is within ±v, volt, the window comparator 101 is activated as an analog switch (input gate). 104 to the recording speed side and the analog switch (feedback gate) 105 to the differential amplifier 39' side are output to connect them, and the pressure control system immediately enters the operating state. However, if there is a temperature drift in the pressure sensor 38 and the rhombic amplifier 39', and the output of the differential amplifier 39' is more than ±v, volts even though the input of the pressure sensor 38 is zero, the zero point detector 101 detects this and connects each gate to the ground side as shown in the figure to stop the pressure control system. This state is indicated by a pilot lamp, etc., so if this display appears, manually operate the potentiometer 106 connected to the offset adjuster 99 to reduce the output of the differential amplifier 39' to below v, volts. Zero point detector 101
Connect as described above and start the pressure control system. By doing so, extremely precise pressure control can be performed during the operation of the x-y plotter. Therefore,
When the operating time is relatively short (about several tens of minutes), even if a pressure sensor with poor temperature characteristics is used, extremely accurate control is possible with a technically easy and inexpensive circuit configuration. moreover,
As mentioned above, there is a problem in that when the surrounding conditions, particularly the temperature, change, the physical properties of the ink change and the amount of ink ejected changes, and this is mainly due to the fact that the viscosity of the ink is affected by the temperature.

In other words, it is generally known that the viscosity of ink, etc. decreases as the temperature increases, but the relationship between viscosity and the amount of ink ejected is that the amount of ink ejected is inversely proportional to the viscosity, as shown in Figure 21. Observed. Therefore, even if a nozzle of the same size and the same ink are used, the applied voltage between the nozzle and the opposing electrode is constant, and the pressure acting on the ink surface is constant, if the ambient temperature is low, the ink will have a high viscosity and will not be ejected. When the amount of ink is small and the temperature is high, the viscosity is low, so the amount of ink ejected increases, and when used as a recording head for an X-Y printer, the line width and density change in proportion to the temperature. . In order to prevent this, according to the present invention, it is also possible to provide means for guaranteeing the temperature of the amount of ink to be ejected. Figure 22 shows an inkjet generator equipped with temperature guarantee means, which utilizes the fact that the applied voltage and the amount of ink jetted are approximately proportional to each other to generate a voltage that can be varied by an external signal as a high-voltage bias power source. A temperature detector 10 is attached to the ink tank 14 as an external signal source to the voltage regulator using a high-voltage bias power supply 30' with a regulator, and detects the temperature of the ink inside the tank.
8. Using, for example, a thermistor and a signal converter 109 that converts the output of the thermistor into an electrical signal, this signal converter 109
According to the output signal from the power supply 30, if the temperature is low, the power supply 30
It works to increase the amount of ink to be ejected by increasing the output voltage of be. Thereby, when the plotting signal to the high-pressure pulse generator 50 is constant, a constant amount of ink can be ejected regardless of the ambient temperature. FIG. 23 shows an embodiment of another temperature guarantee means, which uses a temperature detector 108 that detects the temperature of ink and a signal converter 109 that converts the output into an electrical signal. The output signal is input to the controller 4, and this output signal operates the controller 40 to change the bias level of the pressure control signal, and when the temperature is low, the bias level of the air pressure inside the ink tank generated by the air compression system 42 is changed. In this system, the amount of ink ejected is increased and the amount of ejected ink is increased to compensate for a decrease in the amount of ink ejected due to a drop in temperature, and the opposite operation is performed when the temperature is high. Comparator 3
If the signal from 6 is constant, a constant amount of ink can be ejected regardless of temperature.

Note that the temperature guarantee means shown in FIGS. 22 and 23 may be used together. For example, the bias power supply 30 in FIG.
Exactly the same effect can be obtained by constructing the bias power supply 30' with a voltage regulator shown in FIG. 2 and controlling it with the output of the signal converter 109. In this way, even if the viscosity of the ink changes depending on the ambient temperature, negative feedback is applied to the applied voltage or the pressure acting on the ink surface, so the amount of ink ejected is kept constant, and the amount of ink is always constant regardless of the temperature. A print line with width and density is obtained.

Furthermore, as mentioned above, the amount of ink ejected is affected by the pressure acting on the nozzle inlet, so when used for a long time, the hydrostatic pressure decreases, (a) the amount of ink ejected is no longer proportional to the recording speed, and {b }There is a problem that the jet ON characteristics are extremely deteriorated.

{For machines, the pressure acting on the ink surface is sufficiently larger than the hydrostatic pressure (ink hydrostatic pressure = several centimeters of Aq, pressure acting on the ink surface = several tens of Aq), so it is not a big problem. Regarding b, the pressure acting on the ink surface when the jet is turned on is always zero, that is, the pressure acting on the ink surface is the same as the pressure acting on the nozzle outlet (atmospheric pressure), so the hydrostatic pressure directly affects the tank If the amount of ink within is appropriate, an appropriate meniscus is created before the switching voltage is applied (a, in the same figure), as shown in Figures 24a and 24a to 24a3, and the switching voltage is applied. The ink jetting starts from the moment when (a2 in the figure), and from 1 to
After 3 seconds, a steady state is reached (a3 in the same figure), whereas when the amount of ink is small, a proper meniscus is not formed as shown in q to b3 in Fig. 24 (b, in the same figure). ,
Even if a switching voltage is applied, the injection may not start immediately (b2 in the figure), or the injection direction may deviate from the direction of the nozzle. According to the invention, it is also possible to provide hydrostatic pressure correction means that ensures that the pressure acting on the nozzle inlet remains constant even if the amount of ink in the ink tank decreases.

In order to operate this hydrostatic pressure correction means, it is necessary to detect the hydrostatic pressure of the ink within the ink tank, and this is achieved by detecting the rotation angle of the pulse motor 43 in the pressure control mechanism. This means that the amount of ink decreases (hydrostatic pressure decreases) even when the recording speed signal is constant.
This is based on the fact that as the air volume in the ink tank increases, it is necessary to increase the rotation angle of the pulse motor in response to the decrease in hydrostatic pressure in order to apply pressure proportional to the recording speed signal to the ink surface. It is. In other words, the inkjet recording device of the present invention applies pressure to the ink surface in a manner that corresponds to the recording speed so that a recording line with a constant width can be obtained by ejecting an amount of ink corresponding to the recording speed. This method takes advantage of the fact that the rotation angle of the pulse motor in the pressure control mechanism is proportional to the amount of decrease in hydrostatic pressure. Note that as a method for detecting hydrostatic pressure, recording time may be measured and used.

However, in this case, it is desirable that the amount of ejected ink is always constant. The hydrostatic pressure correction means is a pulse motor 4
3, a potentiometer 110 that detects the rotation angle thereof, a peak value hold circuit 111 that detects and holds the peak value of the potentiometer 110, an inverting amplifier 112 that inverts and amplifies its output, and the inverting amplifier 11
Consisting of a level shift circuit 113 that operates with the output of 2,
The output is Ana.

is added to the comparator 36. The level shift circuit 113 consists of a positive phase amplifier (voltage gain=1), and its output voltage level is shifted by the output from the inverting amplifier 112. Since the rotation angle of the pulse motor 43 can be determined by detecting a value corresponding to a certain reference recording speed signal, the maximum recording speed signal at the maximum recording speed is used as the reference in the embodiment shown in FIG. This is because in the x-Y plotter, the maximum recording speed signal is usually constant. Next, this operation will be explained.

First, when the ink hydrostatic pressure is at a specified value, the level shift circuit 113 passes the maximum recording speed signal as it is to rotate the pulse motor 43, and the potentiometer 110 detects the rotation angle and changes the output to the peak value. The hold circuit 111 detects and holds the output of the inverting amplifier 112 and inputs it to the negative side of the level shift circuit 113. At this time, the output voltage of the potentiometer 110 is set so that the output of the inverting amplifier 112 becomes zero (ground potential). next,
As the hydrostatic pressure decreases as a result of recording, as mentioned above,
The rotation angle of the pulse motor 43 increases with respect to the maximum recording speed signal, the output of the potentiometer 110 increases, the output of the peak value hold circuit 111 increases, and the output level of the inverting amplifier 112 moves to the negative side. Its output is input to a bell shift circuit 113. The level shift circuit 113 shifts its output to the positive side by this input, and acts on the pulse motor 43 in a direction that further increases the output of the potentiometer 110. Therefore, positive feedback is applied to the pressure control mechanism, and the position at which the pulse motor stops is determined by the relationship with the negative feedback loop consisting of the pressure sensor 38 and the feedback amplifier 39. The gains of the positive feedback loop and the negative feedback loop may be determined by experiment. Also,
The ink in the ink tank decreases at an extremely slow rate.
It is preferable that the frequency characteristics of the positive feedback loop, that is, its cutoff frequency, be suppressed to below IHz. In this embodiment, hydrostatic pressure correction is performed by modulating the DC bias of the recording speed signal with the rotation angle of the pulse motor 43 that indirectly detects the amount of ink decrease in the ink tank. This can also be done using . In addition, when the ink nozzle has fallen to the very edge of the nozzle entrance and it is no longer possible to continue recording, this is detected at the maximum rotation angle of the pulse motor, and a warning signal Sa is issued from the peak value hold circuit. Equipment is provided.
In addition, as shown in FIG. 26, the feedback amplifier 39 in FIG. 8 is constituted by a differential amplifier 39', the positive input side of which receives the output from the pressure sensor 38 in FIG. The output of the value hold circuit 111 may be amplified by the positive phase amplifier 114, and the output voltage thereof may be input. Also in this case, when the ink hydrostatic pressure is at a specified value, the output of the positive phase amplifier 114 is set to zero (ground potential), and the output of the pressure sensor is directly amplified by the differential amplifier 39' and sent to the analog comparator 36. However, when the hydrostatic pressure decreases, the output of the peak value hold circuit 111 increases and the output level of the positive phase amplifier 114 shifts to the positive side, which becomes an inverted input to the differential amplifier, so the pressure sensor 25, the pulse motor 43 is adjusted in the direction of increasing the output of the potentiometer 110, and a similar effect can be obtained.
Furthermore, as shown in FIG. 27, the output level of the level shift circuit 113 in FIG. 25 can be shifted in accordance with the recording time.

This is suitable for X-Y plotters where the amount of ink jetted is relatively constant. The structure and operation will be explained below. First, when the output of the counting circuit 117 is set to zero with a specified amount of ink in the ink tank, the output from the D/A converter 118 that has been converted to ○/A and the inverted Amplifier 11
2 becomes zero (ground potential), and the recording speed signal (pressure control signal) is input to the analog comparator 36 without being incline-shifted. Next, when the drawing command signal Sd is input, the jet is injected during this period, as described above, and the hydrostatic pressure becomes low. Therefore, when the amount of ejected ink is constant, the decrease in hydrostatic pressure is proportional to the time during which the drawing command signal is applied. is measured by the counting circuit 117, and the D/
The output level of the level shift circuit 113 is shifted to the positive side via the A converter 118 and the inverting amplifier 112, and the pulse motor 43 is adjusted to increase the air pressure in the ink tank. In this case, the warning signal Sa is generated from the counting circuit 117. Note that various types of clock pulse generators, counting circuits, etc. can be used in this embodiment, but to give an example, the frequency of the clock pulse is 0.1 Hz, and the number of bits of the counting circuit and D/A converter is 0.1 Hz. is 12 bits. With the configuration shown in Figures 25 to 27, the jet is turned on until the amount of ink in the ink tank decreases and the ink surface drops to just below the nozzle entrance, making it impossible to eject any more jets. It is possible to perform the printing very normally, to make the amount of ink ejected accurately proportional to the recording speed, and to use the replenished ink effectively, thus making it possible to print for a long time. The recording time varies depending on the capacity of the ink tank and the amount of ink ejected per unit time, but to give an example, using ink with a specific gravity of 0.9, the ink tank has a capacity of 5' and an amount of ejected ink of 0.4 and 9'. sec, recording speed 2
When the printing speed is 0 m'min, it is possible to continuously record about 4 objects in terms of print length for about 3 hours with one ink replenishment. Additionally, when the air compressor is operated for a long time in addition to the above-mentioned correction means for ink reduction, heat generated from the friction between the air and the cylinder wall and mechanical systems such as the pulse motor is transferred to the air inside the cylinder by conduction. It is also possible to provide means to compensate for the influence of changes in air pressure due to temperature rises caused by this.

In this case, as shown in FIG. 28, in addition to the configuration shown in FIG. 25, a temperature sensor 19 ( a thermistor, etc.), a signal converter 120 that converts the output into an electric signal proportional to temperature, and an inverting amplifier 121 that inverts and amplifies the output, and the amplified output is connected. Next, this operation will be explained. First, when the ink hydrostatic pressure and the cylinder internal air temperature are at specified values, the level shift circuit 113 outputs the maximum recording signal Vmax.
is passed through as it is to rotate the pulse motor 43, and the output of the potentiometer 110 is transferred to the peak value hold circuit 1.
11 detects, holds, and inputs the output of the inverting amplifier 112 to the negative side of the level shift circuit 113. At this time, the output potential of the potentiometer 110 and the output of the inverting amplifier 121 are set so that the output of the inverting amplifier 112 becomes zero (ground potential). Next, as the hydrostatic pressure decreases due to recording, as explained above, the maximum recorded signal V
max, the rotation angle of the pulse motor 43 increases, the output of the potentiometer 110 increases, the output of the peak value hold circuit 111 increases, and the inverting amplifier 112 increases.
The output level of moves to the negative side, and the output level of level shift circuit 1 shifts to the negative side.
13. In response to this input, the level shift circuit 113 shifts its output to the positive side, causing the pulse motor 43 to further increase the output of the potentiometer 110. That is, positive feedback is applied, and the stopping position is determined by the relationship with the negative feedback loop (pressure sensor, feedback amplifier). The gains of the positive and negative feedback loops are determined experimentally. Furthermore, since the rate of decrease of the ink in the ink tank is extremely slow, it is preferable that the frequency characteristics of the positive feedback loop, that is, the cutoff frequency, be kept below IHZ. Next, if the temperature of the air inside the cylinder fluctuates (generally increases for the reasons mentioned above), and if there is no temperature detection system including the inverting amplifier 121, for example, if the temperature of the air inside the cylinder rises. , for the same rotation angle of the pulse motor 43, the air pressure in the air compressor increases too much, and due to the action of the negative feedback loop that detects the pressure, the rotation angle of the pulse motor 43 is decreased, and the inverting amplifier 1
12 outputs are affected by temperature and do not operate properly. The temperature detection system including the inverting amplifier 121 operates to ensure this. That is, when the temperature of the air inside the cylinder becomes higher than a specified value, the rotation angle of the pulse motor 43 is decreased by the action of the negative feedback loop, and the rotation angle of the pulse motor 43 is decreased by the action of the negative feedback loop.
However, the output level of the temperature detection system, that is, the inverting amplifier 121 decreases, and the output level of the inverting amplifier 112 decreases, so that the two act to cancel each other out. , the negative input side of the level shift circuit 113 is prevented from fluctuating the air pressure in the cylinder due to temperature changes, and normally acts to correct only the decrease in the amount of ink in the ink tank. Furthermore, in this embodiment, when the ink level drops to the very edge of the nozzle entrance and it becomes impossible to continue recording, this condition is also detected by the rotation angle (maximum) of the temperature-guaranteed pulse motor 43, and the inverting amplifier 112 The printer is equipped with a warning device which issues a warning signal Sa in response to the output of , and orders the operator to replenish the ink. Moreover, FIG. 29 shows a case where temperature correction is added to the circuit of FIG. Temperature guaranteed. The operation of this temperature correction means is carried out in the same manner as in the case of FIG.
Therefore, in the case of Figures 28 and 29, in addition to being able to record for a long time, even if pressure fluctuations occur in the air inside the cylinder due to temperature fluctuations, it is possible to record at the same recording speed. Even if there are fluctuations in the rotation angle of the pulse motor,
The recording speed signal level or the negative feedback signal level is shifted to the correction side, that is, to the direction of increasing the output of the potentiometer, without being affected by this, so the above fluctuation is corrected, and the pressure acting on the ink surface is adjusted more accurately to the recording speed. It can be controlled in response to signals.

As mentioned above, when an inkjet generator is applied to a recording head such as an X-Y plotter, the ink surface shakes due to the acceleration during movement, and the hydrostatic pressure of the ink applied to the nozzle inlet fluctuates, causing jetting even if the recording speed is constant. There are problems such as variations in the amount of ink resulting in uneven print width, but according to the present invention, these problems can be solved by providing a liquid level stabilizing member in the ink tank, as shown in FIG. This can be solved by In FIG. 30a, a metal or plastic fiber is used as a liquid level stabilizing member, and an appropriate amount of this fiber 122 is loaded into the ink tank 14 and ink is soaked into it.

In this case, almost no liquid shaking occurred even when subjected to moderate acceleration. In Fig. 30b, a large number of laminated metal silks 123 are loaded into the ink tank 14, and the ink is filled up to the upper level of the silks 123. In this case as well, an approximate acceleration is applied. Even when exposed to water, there was almost no liquid shaking.

In Fig. 30c, a plurality of metal nets 123 are placed in the ink tank 14 at certain intervals and filled with ink, and the liquid hardly sways even when subjected to moderate acceleration. It did not occur. In the case of the embodiment shown in FIGS. 30a to 30c, the liquid level stabilizing member acts as an ink filter, so that it is also possible to prevent the holes of the nozzle 15 from being clogged by foreign matter.

FIG. 30d shows a disc-shaped floating lid 1 made of a material having a specific gravity lower than that of the ink, such as foamed polyethylene or cork, and placed on the surface of the ink in the ink tank 14 as a liquid level stabilizing member.
24 was made to float, and even in this case, the liquid did not sway even when subjected to moderate acceleration.

By providing the liquid level stabilizing member in the ink tank as described above, the liquid is stabilized by preventing the liquid from shaking when the inkjet generator ejects the jet while receiving acceleration in a direction perpendicular to the jet ejection direction. In addition, the inkjet generator can be prevented from becoming dirty due to ink, and its maintenance becomes easier.

Further, as the drawing board 20 in the X-Y plotter according to the present invention, it is preferable to use one having electrical conductivity.

This is due to the following reasons. Since the inkjet ejected from the Kasumiba ejection type inkjet generator is a high-speed, minute array of charged particles, the drawing board 20 is highly electrically insulating.
When using , if the recorded object 21 is made of a highly insulating material (for example, synthetic resin such as polyester film), the charges carried by the preceding particles are locally accumulated on the recorded object 21, This may repel the charges of the subsequent particles, causing the subsequent particles to scatter onto the recording object, or particles that have received a larger repulsive force may lose their place and fall onto the annular counter electrode (which is grounded). Even if the recorded object is a conductor, the charge carried by the particles accumulates over time and its surface potential increases, causing the insulating material to become dirty. This is because, as in the case of recorded objects, this will have a negative effect on the jet ejection. This adverse effect imparts electrical conductivity to the drawing board, making its potential the same as or lower than that of the annular counter electrode, thereby preventing charging of the recording material due to the charges carried by the preceding jet, and also preventing the recording material from being charged by charges carried by the preceding jet. This can be prevented by restraining the electric lines of force generated from the ink so as to face the drawing board instead of directing them towards the annular counter electrode. There are various methods for imparting conductivity to drawing boards, but in order to enable the use of conventional contact-type recording tools, we have developed a method to provide electrical conductivity without impairing the ballistic properties of conventional drawing boards. A method of imparting is preferred.

This can be done, for example, by embedding or pasting a metal plate or mesh-like metal wire in a sheet made of the same material as the conventional drawing board, or by adding a sufficient amount of conductivity to the drawing board forming material to the extent that it does not impair its elasticity. This can be achieved by adding and dispersing fine powder and then molding. A conductive member 126 made of a mesh-like metal wire, for example, iron wire, copper wire, nichrome wire, etc., is sandwiched between two rubber sheets 125, and both are bonded with adhesive or the like, as shown in FIG. 31a. It is fixed in place.

When a nichrome wire is used as the metal wire, when a current is passed through it, the drawing board is heated by Joule heat, which increases the temperature of the recorded object, heats the ink on the recorded object, and shortens the drying time. There is an advantage that The drawing board 20 shown in FIG. 31b is made of rubber made of the same material as the conventional rubber drawing board.
After adding and dispersing conductive fine powder such as carbon or silver in an amount that does not impair its ballistic properties and performing conductive treatment, it is molded into a predetermined size.

In this case, it is desirable that the specific resistance is 1 or less. The drawing board 2 in Fig. 31c is made by pasting a conductive sheet 127, which has been subjected to the same conductive treatment as the drawing board in Fig. 31b, to an insulating sheet 125 made of rubber, which is the same material as the conventional drawing board. It is.

When this drawing board is set on an X-Y plotter, it is mounted with the surface that has not been subjected to conductive treatment, that is, the surface on the insulating sheet side, facing the nozzle. Generally, when conductive fine powder is dispersed in rubber, it is colored, but since there are cases where you want the color to be as white as possible for the X-Y plotter drawing board,
This diagram is effective in such cases. When using a drawing board configured as described above, for example, as shown in FIG. 16, or as shown in Figure b, conductive member 1.
26 is grounded, the potential of the annular counter electrode 16 is made higher than the ground potential, and the other end of the conductive section 126 is connected to a heating power source P. W. Connect.

In the latter case, the voltage of the heating power source is preferably 50 V or less in order to prevent the electrical potential of the conductive member from having an adverse effect on the jet. In addition, the third
The devices shown in FIGS. 1b and 1c can also be used in the same manner. By using such a drawing board, ■ the charge carried by the preceding jet and accumulated on the recording medium does not adversely affect the generation of the jet or the subsequent jet, and the quality of the image is significantly improved; By heating the plate, the ink adhering to the recording medium dries quickly, and (2) even when using conventional contact-type writing instruments, it can be used in common without any problems.

As explained above, in the inkjet recording device according to the present invention, since the inkjet generating device is provided with a pressure control means for controlling the pressure acting on the ink surface in the ink tank in accordance with the recording speed, recording is possible. The amount of ink jetted according to the speed can be controlled extremely accurately, and the responsiveness is extremely good, so even if the recording speed changes due to ×1Y movement, the recording line width is always kept constant. However, it has many advantages such as being able to perform high-speed recording without any inconvenience.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an X-Y plotter equipped with an inkjet recording device according to the present invention, Fig. 2a is a plan view of the inkjet generator, Fig. 2b is a partially sectional front view thereof, and Fig. 2c is a sectional view taken along line 1-1 in Figure 2b, Figure 3a
is a plan view of the head body, Figure 3b is a cross-sectional view of the inkjet generating section, Figure 3c is a cross-sectional view of the head body, and Figure 3d is a cross-sectional view of the head body.
is a plan view of the lower body of the head, Figure 3e is an enlarged sectional view of the vicinity of the nozzle, Figure 3f is a bottom view of the counter electrode, and Figure 4 is Figure 3d when the inkjet generator is attached to the head body. FIG. 5 is a graph showing the relationship between the pressure acting on the ink surface and the amount of ink ejected.
The figure is a graph showing the relationship between the amount of injected ink and the recorded line width.
Figure 7 is a block diagram of the servo control mechanism, Figure 8 is a block diagram of the recording speed signal generation mechanism in the pressure control mechanism, Figure 9 is a block diagram of the pressure control mechanism, and Figure 10 is the pressure control mechanism of Figure 9. Fig. 11 is a schematic diagram showing the state of the ink jet when the jet is turned on and off, Fig. 12a is a plan view of the air compression system in the pressure control mechanism of Fig. 9, Fig. 12b is a cross-sectional view taken along line A-A in FIG. 12a, FIG. 13 is a partial cross-sectional view taken along line B-B in FIG. 12a, and FIG. 14 is a graph showing pressure waveforms in the compressor and in the ink tank. FIG. 15 is a cross-sectional view of main parts showing a modification of the compressor, FIGS. 16 and 17 are block diagrams showing a modification of the pressure control mechanism, and FIG. 18a is a modification of the air compression system in the pressure control mechanism. 1st plan view showing
Figure 8b is a sectional view taken along line 1-1 in Figure 18a, and Figure 19
The figure is a block diagram of the pressure control mechanism equipped with a disturbance prevention circuit.
Fig. 20 shows a circuit showing a specific example thereof, Fig. 21 is a graph showing the relationship between ink viscosity and ejected ink amount, and Figs. 22 and 23 show main parts of an inkjet recording device equipped with temperature guarantee means. FIG. 24 is a schematic diagram showing the influence of hydrostatic pressure on jet ON characteristics. FIGS. 28 and 29 are block diagrams showing the main parts of a pressure control mechanism equipped with a hydrostatic pressure correction means and a pressure guarantee means, and FIG. 30a
- d are sectional views showing various examples of inkjet generators provided with liquid level stabilizing members, Figs. 31 a - 31 c are sectional views of various drawing boards, and Fig. 32 is a schematic diagram showing the state in which they are used. 1...×-Y plotter, 2... Main body,
3, 4... ...Rail, 5...X-moving girder, 6
, 7...Support stand, 8...X-servo motor, 9...Y-direction rail, 10...Mover, 11...Servo motor, 12...Head body, 13...・Inkjet generator, 14... Ink tank, 15
...Nozzle, 16...Counter electrode, 18...
...Air piping, 19...High voltage cable, 20...
...Drawing board, 21... Recorded object, 22, 31... Interface, 23, 23'... Comparator, 24, 24'.
...D/A converter, 25, 25'... Servo amplifier, 26, 26'... Speed detector, 2
7, 27'... Position detector, 28, 28'...
Feedback amplifier, 29, 29'...A/D converter,
30...Bias power supply, 32, 33...Squaring circuit, 34...Addition circuit, 35...
Square root circuit, 36...analog comparator, 37...compressor, 38...pressure sensor, 39...
Feedback amplifier, 40...controller, 41...pulse motor drive circuit, 42...air compression system, 43...pulse motor,
44...Cam, 46...Converter, 47
...Cylinder, 48 ...Piston, 5
0... High pressure pulse generator, 53... Needle valve, 55, 57... Amplifier, 56... Gain selector, 58... Pulse motor, 59・
...Auxiliary pump, 61...Positioning pin, 6
2... Nozzle fixing cylinder, 63... Nozzle guide ring, 64... Outer cylinder, 65...○ ring, 66... Annular hole, 67... ...notch, 68
, 69... annular groove, 70... annular hole, 71
...Notch groove, 72...Ink tank fixing ring, 78...High voltage electrode ring, 79...
High voltage electrode rear piece, 80... Connector, 81, 84...
... Lead wire, 82 ... Counter electrode ring,
83... Counter electrode piece, 86... Lid,
87... Loupe for jet observation, 94... Piston, 9
5...Cylinder, 96...Piston rod, 97...Pinion, 98...Input gate, 99...Offset adjuster,
100... Feedback gate, 101... Zero point detector, 102... Controlled object, 103...
... Output detector, 104, 105 ... Analog switch, 106, 110 ... Potentiometer, 10
8... Temperature detector, 109... Signal converter, 11... Peak value hold circuit, 112, 1
21... Inverting amplifier, 113... Level shift circuit, 114... Positive phase amplifier, 115
......Clock pulse generator, 1 16...AND gate, 1 1 7...Counting circuit, 118...D
/A converter, 119...Temperature sensor, 120.
t...Signal converter, 122, 123, 124...
・Liquid level stabilization member, 125...Insulating sheet,
127... Conductive sheet. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 8 Figure 7 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Fig. 18 Fig. 19 Fig. 21 Fig. Z Fig. 23 Fig. 24 Fig. 25 Fig. 26 Fig. 27 Fig. 28 Fig. 30 Fig. 31 Fig. 32

Claims (1)

[Claims] 1 A recording head is an ink tank, a nozzle for guiding ink in the ink tank to the outside, and a counter electrode for forming an electric field between the nozzle and the nozzle while moving the recording head. In an inkjet recording device that performs image recording by applying an inkjet voltage between an opposite electrode and an inkjet command signal in response to an inkjet command signal, the inkjet recording device is connected to an ink tank via a flexible air pipe, and is connected to an ink tank via a flexible air pipe. An air pressure adjusting means for adjusting the air pressure acting on the ink surface in the ink tank, a means for detecting the air pressure and outputting a corresponding pressure signal, and a means for detecting the moving speed of the recording head and outputting a corresponding speed signal. and means for receiving the pressure signal and the speed signal and outputting a signal for correcting the air pressure to the air pressure adjusting means, and controlling the amount of ink ejected in the ink tank. An inkjet recording device featuring: