JPH09109385A - Discharge unit and ink jet printer with the discharge unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control the discharge amount of fluidized substance such as ink per unit time by generating a traveling wave of the opposite discharge direction at the contact surface of a discharge unit having an opening in the object direction of the supplied substance with the substance. SOLUTION: An opening 13 is formed in the discharging direction of ink at the nozzle 11 of a printer head 10, and an ink channel 12 extending in the opposite direction to the ink discharge direction I from the opening is formed. An ink line 16 is connected from an ink tank 14 to the channel 12 through an ink control valve 15, which is driven by the drive signal of a control valve driving circuit 42. Electrostrictive vibration elements 17 are aligned along the channel 12 on the outer periphery of the nozzle 11, a high-frequency AC power source 34 is connected thereto, and driven by the drive signal from an AC power source drive circuit 41 for generating a traveling wave advanced in the opposite direction to the ink discharge direction I on the inner periphery of the channel 12. Accordingly, the discharge speed of the substance can be accurately controlled by regulating the amplitude and frequency of the wave, and printing with delicate dark and pale density change can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ejection device for ejecting a fluid substance such as ink, and an ink jet printer equipped with this ejection device.

[0002]

2. Description of the Related Art Ink jet printers intermittently eject ink little by little and eject the ink as dots on paper.

As a method of ejecting the ink, conventionally, air is stored in a pressure chamber until the pressure reaches a constant pressure, and the air is rapidly blown out to eject the ink, or the ink is partially heated by a heater. There is a bubble jet method in which bubbles are generated by doing so and ink is ejected by the pressure.

[0004]

However, in any of the above-mentioned conventional techniques, it is difficult to accurately control the ink ejection amount per unit time, and it is difficult to express subtle shading. There is a point.

Specifically, in the case of utilizing air pressure,
Since there is no exact proportional relationship between the pressure when the compressed air is blown out from the pressure chamber and the amount of ejected ink, and it is difficult to manage the pressure in the small pressure chamber, it is not possible to express delicate shades. Further, in the bubble jet method, since the pressure change when the ink boils is used, it is difficult to manage this pressure change, and thus it is not possible to express delicate shades.

The present invention has been made by paying attention to such a conventional problem, and an ejection device capable of accurately controlling the ejection amount of a fluid substance such as ink per unit time, and the ejection device. An object of the present invention is to provide an inkjet printer including the device.

[0007]

A discharge device for achieving the above object is supplied with a fluid substance, and an opening (13) is formed in the intended discharge direction (I) of the fluid substance. The opening (1) of the discharge body (11) is provided on the contact surface between the discharge body (11) and the fluid substance of the discharge body (11).
3) traveling wave generating means (17, 40, 41, 45) for generating traveling waves in the direction opposite to the ejection direction (I),
It is characterized by having.

Here, it is preferable that the traveling wave generating means has traveling wave velocity changing means (40, 41) for changing the amplitude and / or frequency of the traveling wave.

Further, the above-mentioned ejection device, the ink supply means (14, 15, 16) for supplying the ink as the fluid substance to the ejection member (11) of the ejection device, and the ejection member (11). An ink jet printer can be configured by combining the substance to be printed (S) to which the ink ejected from is applied with the moving mechanism (20, 30) that relatively moves the ejecting body (11). In this case, the ejection body (11) is a nozzle having therein an ink flow path (12) extending from the opening (13) in a direction opposite to the ejection direction (I).

In the above, the code in () is
It is the code of the corresponding part of the embodiment described below.

[0011]

DETAILED DESCRIPTION OF THE INVENTION An inkjet printer according to an embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 2, this ink jet printer has a printer head 10 for ejecting ink toward a printing paper S, a head moving mechanism 20 for moving the head 10, and a paper feeding mechanism for moving the printing paper S. 30 and a drive circuit 4 for driving the mechanism in the head 10.
1, 42, a head movement drive circuit 43 for driving the head movement mechanism 20, a paper feed drive circuit 44 for driving the paper feed mechanism 30, and these drive circuits 41, 42, 4
And a control unit 40 for controlling 3, 44.

As shown in FIG. 1, the printer head 10 includes an ink tank 14 for storing ink and a nozzle (ejection body) for ejecting the ink from the ink tank 14.
11, an ink control valve 15 that limits the ink supplied from the ink tank 14 to the nozzle 11, a plurality of electrostrictive vibrating elements 17, 17, ... That vibrate the nozzle 11, and a head casing (not shown) that covers these elements. .) And.

An opening 13 is formed in the nozzle 11 in the ink ejection direction, and an ink flow path 12 extending from the opening 13 in the direction opposite to the ink ejection direction I is formed. An ink line 16 extending from the ink tank 14 is connected to the ink flow path 12. The ink control valve 15 is provided in the ink line 16. The ink control valve 15 is connected to a control valve drive circuit 42, and is driven by a drive signal from this circuit 42. Nozzle 11
A plurality of electrostrictive vibration elements 17, 17, ... Are arranged along the ink flow path 12 on the outer periphery of the. These electrostrictive vibration elements 17, 17, ... Are made of PZT (zirconate titanate).
It is formed with. A high-frequency AC power supply 45, 45, ... Is connected to each of the electrostrictive vibration elements 17, 17 ,.
The high-frequency AC power supplies 45, 45, ... In order to generate a traveling wave traveling in a direction opposite to the ink ejection direction I on the inner peripheral surface of the ink flow path 12, the electrostrictive vibration elements 17, 17 ,. , AC power is supplied so that a constant phase difference occurs. Each of the high-frequency AC power supplies 45, 45, ... Is connected to the AC power supply drive circuit 41 and is driven by a drive signal from the circuit 41.

In the ink casing, a plurality of nozzles 11, 11, ... Are arranged so that the respective openings 13 face the same direction.
Is provided. Specifically, in this embodiment, the 24 nozzles 11, 11, ... Are two-dimensionally arranged vertically and horizontally.

As shown in FIG. 2, the head moving mechanism 20 includes a lead screw screw 21 extending in a direction perpendicular to the ink ejection direction I, a head moving motor 22 for rotating the lead screw screw 21, and a head moving motor. 22 and a coupling 23 for connecting the lead screw 21 with each other,
It has a nut 24 screwed to the lead screw 21 and fixed to the head 10, and a linear guide 25 extending in a direction parallel to the lead screw 21 and guiding the moving direction H of the head 10. Head moving motor 22
Is connected to the head movement drive circuit 43, and this circuit 43
It is driven by the drive signal from.

The paper feeding mechanism 30 is a device for feeding the paper S in a direction perpendicular to the ink ejection direction I and the head moving direction H, and a drive shaft 31 extending in a direction parallel to the lead screw 21 of the head moving mechanism 20. , A plurality of drive rollers 32, 32, ...
, A plurality of driven rollers 33, 33 arranged so as to face the drive rollers 32, 32, ..., A paper feed motor 34 for rotating the drive shaft 31, and a rotational force of the motor 34. 31 and a plurality of gears 35, 35 for transmitting to 31. The paper feed motor 34 is connected to a paper feed drive circuit 44 and driven by a drive signal from this circuit 44.

Next, the principle of ink ejection of the above-described ink jet printer will be described with reference to FIG. In the figure, reference numerals of corresponding parts in the above embodiment are shown in parentheses.

A plurality of vibrating elements 7, 7, ..., Which expand and contract when a voltage is applied, are arranged in a line on the lower surface 1a of the vibrating object 1, and are attached to each of the vibrating elements 7, 7 ,. When an AC voltage having an appropriate phase difference is applied from 5, ..., A surface wave as a traveling wave can be generated on the upper surface 1b of the vibrating object 1. When a traveling wave is generated on the upper surface 1b of the vibrating object 1, when the object 2 is brought into contact with the upper surface 1b, a force that moves the object 2 in a direction 9 opposite to the traveling direction 8 of the traveling wave acts. This is the same as the basic principle of an ultrasonic motor using surface waves. Therefore, by bringing a liquid substance such as ink or powder, or a fluid substance such as a granular substance into contact with the upper surface 1b of the vibrating object 1 in which the traveling wave is generated, the fluid substance moves in the traveling direction of the traveling wave. 8 receives a force in the direction 9 opposite to the direction 8 and moves in the direction 9 opposite to the traveling wave.

Now, let us say that the maximum vibration velocity at a specific point on the upper surface of the vibration target 1 is Vm. As shown in FIG. 3, the specific point of the vibrating object 1 makes an elliptic motion 3, and therefore the following (Equation 1) holds for the maximum vibration velocity Vm.

Vm = 2π · f · a · q (Equation 1) f: Vibration frequency a: Vibration amplitude q: The ratio of the major axis to the minor axis of the surface wave in elliptical motion (q <
1) Here, the value of each parameter in (Equation 1) is set to f = 4
0 (kHz), a = 10 (μm), q = 1/10,
Vm = 251 (mm / s). This maximum vibration speed V
Since m = 251 (mm / s) is a speed sufficient for ejecting ink, it can be said that the embodiment described above can obtain the ink ejection speed required for printing. Further, since the vibration frequency f and the vibration amplitude a are in a proportional relationship with the maximum vibration speed Vm, the maximum vibration speed Vm can be easily changed by changing them.
Therefore, in the embodiment described above, the AC power supply 45
By adjusting the frequency or the output from the AC power source, the ink ejection speed can be controlled. Therefore, the ejection speed of the ink, in other words, the ejection amount of the ink per unit time can be easily controlled, so that it is possible to obtain a delicate gradation change at the time of printing.

Next, the operation of the ink jet printer described above will be described. At the time of printing, the head movement drive circuit 43 which receives the control signal from the control unit 40
Drives the head moving motor 22, and the paper feed drive circuit 44 drives the paper feed motor 34. When the head moving motor 22 is driven, the lead screw screw 21
Rotates, and the nut 24 and the head 10 move by the rotation amount of the lead screw 21. Further, when the paper feed motor 34 is driven, the drive rollers 32, 32, ...
The sheet S sandwiched between the rollers 2, 32, ... And the driven rollers 33, 33 ,. With the series of operations described above, the relative positional relationship between the head 10 and the paper S changes.

Further, the control valve 1 in the printer head 10
5 opens, ink starts to be supplied from the ink tank 14 to the ink flow path 12 in the nozzle 11, and the AC power supply drive circuit 41 receives a control signal from the control unit 40.
Is driven to drive the AC power supply 45. Each AC power source 4
When 5 is driven and AC power is supplied to each electrostrictive vibrating element 17, each electrostrictive vibrating element 17 starts to vibrate with a constant phase difference, and advances to the inner peripheral surface of the ink flow path of the nozzle 11. Waves are generated. As a result, the ink in the ink flow path 12 starts moving in the direction opposite to the traveling direction of the traveling wave, and is ejected from the opening 13 of the nozzle 11 toward the printing paper S.

If a control unit 40 is instructed in advance to change the density of the print result,
In response to an instruction from the control unit 40, the output from each AC power supply 45 to each electrostrictive vibrating element 17 changes and the nozzle 11
The amplitude of the traveling wave on the inner peripheral surface of the ink flow path changes, and the discharge amount of ink per unit time changes.

As described above, in one embodiment of the present invention,
By changing the amplitude or frequency of each electrostrictive vibrating element 17, the amount of ink ejected per unit time can be accurately controlled, so that a slight shade change can be applied to the printed matter. In addition, in one embodiment of the present invention, although the printed matter can be subtly changed in shade, it is structurally simpler than the other inkjet printers described in the related art, so that the manufacturing cost is reduced. It can be reduced. Further, unlike a wire dot printer or a thermal transfer printer, the head does not move while being in contact with the paper, so that not only high-speed printing is possible, but also noise during printing can be suppressed to a very low level.

Although an inkjet printer has been described above as an embodiment of the present invention, the present invention is not limited to an inkjet printer, and as described in the section of the principle of ink ejection, liquids other than ink, powder, etc. ,
It goes without saying that it can also be used as a discharge device for particulate matter.

[0027]

According to the present invention, the discharge speed of the fluid substance can be accurately controlled by changing the amplitude or frequency of the traveling wave generated on the contact surface of the discharge body with the fluid substance. As a result, when the present invention is applied to an ink jet printer, it is possible to make a slight shade change in a printed matter.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a printer head as an embodiment according to the invention.

FIG. 2 is an explanatory diagram showing a configuration of an inkjet printer as an embodiment according to the invention.

FIG. 3 is an explanatory diagram showing the principle of discharging a fluid substance according to the present invention.

[Explanation of symbols]

10 ... Printer head, 11 ... Nozzle, 12 ... Ink flow path, 13 ... Opening, 14 ... Ink tank, 15 ... Ink control valve, 16 ... Ink line, 17 ... Electrostrictive vibration element, 20
... Head moving mechanism, 21 ... Lead screw screw, 22
... Head moving motor, 24 ... Nut, 25 ... Linear guide, 30 ... Paper feeding mechanism, 31 ... Drive shaft, 3
2 ... drive roller, 33 ... driven roller, 34 ... paper feed motor, 40 ... control unit, 41 ... AC power supply drive circuit,
42 ... Control valve drive circuit, 43 ... Head movement drive circuit, 4
4 ... Paper feed drive circuit.

Claims (3)

[Claims] 1. An ejection device for ejecting a fluid substance, wherein the fluid substance is supplied and an opening is formed in the intended ejection direction of the fluid substance; And a traveling wave generating means for generating a traveling wave in a direction opposite to the ejection direction from the opening of the ejection body, on the contact surface with the organic substance. 2. The ejection device according to claim 1, wherein the traveling wave generation means has traveling wave velocity changing means for changing the amplitude and / or frequency of the traveling wave. . 3. The ejection device according to claim 1, an ink supply unit for supplying the ejection body of the ejection device with ink that is the fluid substance, and the ink ejected from the ejection body. A moving mechanism that moves the ejection body relative to the substance to be printed, wherein the ejection body has a nozzle in which an ink flow path extending from the opening in a direction opposite to the ejection direction is formed. An inkjet printer characterized in that