JPS592620B2 - ink ejection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intermittent ink jetting device for recording characters, symbols, images, etc. in response to input electrical signals.

The structure of an intermittent ink jetting device that has been commonly used in the past is shown in FIG.

The following explanation will be given based on FIG. 1. A part of the wall constituting the ink chamber 1 is composed of a vibrating element 2 such as a bimorph that converts electrical energy into mechanical displacement, and one end of the ink chamber 1 is provided with a backflow prevention means. It is connected to an ink supply source through a provided supply path 3, and an orifice 4 for ejecting ink is formed at the other end. When an electric signal is input, the vibrating element 2 is displaced in a direction to reduce the volume inside the ink chamber 1 in response to the electric signal, and the ink inside the ink chamber 1 is pressurized and the ink is moved forward from the orifice 4. The ink droplets fly as one or more ink droplets. Thereafter, the vibrating element 2 returns to its original standard state, and the ink chamber 1 returns to its initial volume. At this time, ink is replenished into the ink chamber 1 through the supply path 3, and a waiting state for the next operation is established. below,
The same operation is repeated and the ink droplets fly toward the green paper in order, and recording is executed on the recording paper. The ink ejecting device having the above configuration is useful as a method of forming ink droplets using pressure changes based on mechanical displacement, but air is mixed into the ink chamber 1, orifice 4, supply path 3, etc. In this case, the volume change in the ink chamber 1 due to the operation of the vibrating element 2 will be absorbed by the bubbles formed by this air, making it impossible to apply sufficient pressure to the ink, resulting in a crack. , resulting in incomplete ink droplet ejection.

FIG. 2A shows the electric signal waveform input to the ink jetting device of FIG. 1, and FIGS. 2B, C, and D show the corresponding displacement ΔX of the vibrating element 2.

In a normal state in which the ink chamber 1, orifice 4, and supply path 3 are filled with ink and no air is mixed in, the displacement ΔX of the vibrating element 2 responds to an electric signal and maintains a normal displacement state, as shown in FIG. 2B. Continue repeating. When there is no ink in the ink chamber 1 or the like and the chamber is filled with air, the displacement ΔX of the vibrating element 2 exhibits irregular vibrations as shown in FIG. 2C. Further, when ink exists in the ink chamber 1 etc. and some air is mixed in, the displacement ΔX of the vibrating element 2 becomes as shown in FIG. 2D. As described above, it has been experimentally confirmed that when air exists in the ink chamber 1, etc., the displacement △X of the vibrating element 2 contains a high frequency vibration component during one period, and the displacement state becomes irregular. It was done. SUMMARY OF THE INVENTION In view of the above-mentioned problems of the conventional ink ejecting apparatus, it is an object of the present invention to provide an ink ejecting apparatus with improved reliability by making full use of technical means. Hereinafter, the present invention will be explained in detail according to embodiments with reference to the drawings.

FIG. 3 is a sectional view of a main part of an ink jetting device showing an embodiment of the present invention.

As in FIG. 1, a part of the wall surface of the ink chamber 1 is made up of a vibrating element 2 such as a bimorph, and is provided with a supply path 3 and an orifice 4 serving as an ink jetting port.

A part of the vibrating element 2 constitutes a detector 5 for detecting its displacement. The ink jetting operation is performed by operating the vibrating element 2 in response to an input electrical signal, as in the conventional case. FIG. 4 is a block diagram of an electric circuit connected to the ink jetting device shown in FIG. 3.

The signal obtained from the detector 5 is input to an amplifier circuit 6 for impedance matching and signal amplification, and the output of the amplifier circuit 6 is input to a detection circuit 8 via a high-pass pool 17. The error signal output indicating the presence or absence of contamination is output to the output terminal 9.

When the ink ejecting device VC having the above configuration is operating normally without air entering the ink chamber 1, etc., the displacement ΔX of the vibrating element 2 changes as shown in FIG. 2B. A detector 5 configured as a part of the vibrating element 2 generates a displacement signal corresponding to the displacement of the vibrating element 2, and the signal is inputted to a high-pass filter 7VC via an amplifier circuit 6. Since the frequency of the input signal is low, the high-pass filter 1 cuts off the signal and does not input the signal to the detection circuit 8, so that no error signal is output and the output terminal 9 exhibits a 0'' state. However, if air gets into the ink chamber 1 during the recording operation,
, D, the vibrating element 2 exhibits a displacement containing a high frequency vibration component, and a displacement signal from the detector 5 corresponding to this displacement is output via the amplifier circuit 6 to a high-pass film memo. The high-pass filter 7 passes high-frequency vibration components caused by air inclusion, and its output signal is sent to the detection circuit 8VC.
The error signal ``1'''' is detected from the detection circuit 8 and is a high-pass filter output signal based on air entrainment, and is output to the output terminal 9.The error signal appearing at the output terminal 9 is displayed on a display means such as a lamp or other The operator is notified by the notification means, and the operator performs the air evacuation operation.Alternatively, the error signal activates the electromagnet, motor, etc., and the ink tank (
The ink pressure supplied from the ink (not shown) is kept high for a predetermined period of time, and a predetermined amount of ink is forced to flow out through the supply path 3, the ink chamber 1, and the orifice 4, and the mixed air is discharged at the same time. By performing the automatic air evacuation operation, the ink jetting failure state is canceled and reliability is significantly improved. FIG. 5 is a sectional view of main parts showing another embodiment of the present invention, in which the vibrating element 2, which partially constitutes the detector 5, has an ink chamber 1 partially forming a wall surface, and an ink reservoir 1 in front of the orifice 4.
1, a supply path 12 for supplying high-pressure ink for air discharge to the ink chamber 1, an electromagnet 16 for adjusting the ink supply pressure, and an electromagnet 1.
Always press the lever 16a upward and press the stopper 11.
A pressurizing chamber 14 is configured, which is brought into contact with and stopped by the pressurizing chamber 7 .

The pressurizing chamber 14 is made of a bellows 13 made of an elastic material, and the pressure is such that the ink reservoir 11 is maintained in equilibrium with capillary action without naturally flowing out from the ink tank (not shown) to the slit 10. After ink is supplied, the vibration element 2 is operated to reduce the internal volume of the ink chamber 1, and one or more ink droplets are ejected forward from the liquid level of the ink reservoir 11, and then the ink is replenished. be. In order to prevent ink from flowing back into the proboscis pressure chamber 14 via the supply path 12,
The viscous resistance of the supply path 12 is designed to be sufficiently large compared to the viscous resistance of the orifice 4. When air enters the ink chamber 1 etc. of the ink jetting device having the above configuration, an error signal is outputted as described above, and in response to this error signal, the electromagnet 16 is operated for a predetermined time to overcome the auxiliary force of the bellows 13. By compressing the pressurizing chamber 14 and supplying the ink to the ink chamber 1 through the supply path 12 at a high pressure, a predetermined amount of ink is caused to flow out through the orifice 4, thereby simultaneously expelling the mixed air. Thereafter, when the power supply to the electromagnet 16 is stopped, the lever 16a rises due to the elasticity of the bellows 13, contacts the stopper 17VC, and returns to its original state. In addition, bellows 13
Since the viscous resistance experienced by the supply path 12 is sufficiently large against the elastic force of the ink reservoir 11, air is unlikely to break through the liquid film of the ink reservoir 11 and enter the orifice 4. The above-mentioned air evacuation operation may be performed immediately before starting the recording operation to constitute a standby state for recording. As is clear from the above embodiments, the ink jetting device according to the present invention detects the intrusion of air into the ink chamber, orifice, etc., and detects the displacement of the vibrating element, that is, the abnormality in the response characteristic to the input signal, and generates an error signal. As a result, the reliability of the device has been improved by performing an operation to discharge the mixed air in response to an error signal. The driving voltage waveform of the vibrating element used in the present invention is not limited to the rectangular pulse shown in FIG. It is also effective to eject ink using

In addition to detecting mixed air, the present invention can also be used as a means of detecting clogging, since the displacement of the vibrating element shows a different response from normal when the orifice is clogged, and an error signal is generated. , high pressure is applied to the ink according to the error signal, and high pressure is applied. Clogging can also be cleared by feeding ink into the orifice. In the present invention, a part of the wall surface constituting an ink chamber having an ink supply port through which ink is supplied from an ink tank and an ink droplet jetting port through which ink is pulverized into particles is displaced in response to an electric signal. In the ink ejecting device comprising a vibrator that changes the volume inside the ink chamber, a part of the vibrator forming a part of the wall surface of the ink chamber is provided with a detection means for detecting a displacement state of the vibrator. Additionally, an error detection means is provided for detecting an abnormality in the displacement state of the vibrator from an electric signal from the detection means, and further includes a drive source that is driven for a predetermined period of time in response to the error signal from the error detection means. A high-pressure ink supply means that maintains a high pressure in the pressure chamber for a predetermined period of time is connected to the ink chamber separately from the ink supply system from the ink tank, and the connecting portion is provided with a backflow to the high-pressure ink supply means when the volume inside the ink chamber changes. Since the detection means operates integrally with the vibrator, it can faithfully extract the displacement of the vibrator as an electric signal, and based on this faithful electric signal, Abnormality detection of the vibrator is also performed accurately and reliably. Further, in response to the accurate error signal, the high-pressure ink supply means is automatically driven for a certain period of time, so that air entrained in the ink chamber or clogging can be automatically eliminated. Moreover, this high-pressure ink supply means is in-line. By providing a means for preventing backflow from the ink chamber and connecting it to the ink chamber when the volume inside the ink chamber changes, the ink droplet formation is not adversely affected.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional ink ejecting device. FIG. 2A is a drive pulse waveform showing an input signal to the vibrating element shown in FIG. 1, and FIGS. 2B, C, and D are explanatory diagrams showing displacement waveforms of the vibrating element. FIG. 3 is a sectional view of a main part of an ink jetting device showing an embodiment of the present invention. FIG. 4 is a block diagram showing an electric circuit connected to the ink jetting device shown in FIG. 3. FIG. 5 is a sectional view of a main part of an ink jetting device showing another embodiment of the present invention. 1... Ink chamber, 2...
... Vibration element, 3... Supply path, 4... Orifice,
5...Detector, 7...High pass filter.

Claims (1)

[Claims] 1. A part of the wall surface constituting an ink chamber having an ink supply port through which ink is supplied from an ink tank and an ink droplet ejection port through which ink is made into particles and ejected is displaced in response to an electric signal, and the inside of the ink chamber is In an ink ejecting device comprising a vibrator that changes volume, a part of the vibrator constituting a part of the wall surface of the ink chamber is provided with a detection means for detecting a displacement state of the vibrator, and the detection means an error detection means for detecting an abnormality in the displacement state of the vibrator from an electric signal from the error detection means; A high-pressure ink supply means that maintains a high pressure for a certain amount of time is connected to the ink chamber separately from the ink supply system from the ink tank, and the connecting portion is provided with means for preventing backflow to the high-pressure ink supply means when the volume inside the ink chamber changes. ink jetting device.