JPS60225761A - Inkjet recorder - Google Patents

Abstract

PURPOSE:To enable the recording of a high definition image to be made by applying DC voltage in such a direction as to intensity the polarization of an electromechanical convertion body to prevent the mechanical displacement due to aged deterioration in the electromechanical conversion body to become the cause of lowering the quality of a recording image. CONSTITUTION:An electromechanical conversion body 11 is joined on a glass tube having an orifice with the diameter 40mum as recording head, a filter 14 is mounted on the liquid inflow side of a nozzle 12 and then, the nozzle is emmersed in a subtank 21 on the filter 14 side thereof to make an inkjet recorder. Normally, a discharge signal is inputted into a trigger input terminal 35 of a discharge pulse and the conversion body 31 is displaced mechanically with the application of a desired voltage thereto 31. At the time of the repolarization, a repolarization signal is inputted into a trigger input terminal 36 of a repolarization pulse. This allows a voltage with the plurality opposite to that in the recording to be applied into the conversion body 31 thereby always ensuring a stable image recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an inkjet recording device, and more particularly to an inkjet recording using an electrical/mechanical converter as an energy generator for generating energy for forming flying droplets. Regarding equipment.

[Prior art]

BACKGROUND ART Inkjet recording methods have traditionally attracted attention because they can record on so-called plain paper without using any special means such as fixing, and because the noise during recording is so small that it can be ignored.

One such recording method is a recording method that uses an electromechanical transducer and applies mechanical displacement of the transducer to the recording liquid to cause droplets to fly from an ejection orifice and perform recording. Are known.

An inkjet recording device for achieving the recording method described above usually uses a polymeric material (for example, an adhesive) or a low melting point material in a member constituting an energy application chamber that is filled with a recording liquid and communicates with an ejection orifice. They are joined by an adhesive material such as an alloy.

By the way, in such a configuration, the thermal expansion coefficient of the electrical/mechanical converter itself and the thermal expansion coefficients of the members constituting the adhesive material energy action chamber are generally different, so the environmental temperature in which the device is placed, An external mechanical force may be applied to the electrical/mechanical converter depending on the temperature of the recording liquid or the like. In particular, if the device is left in a high or low environmental temperature for a long period of time, an external force is applied to the electrical/mechanical converter during that time, and external stress may remain inside the converter. As a result, the amount of mechanical displacement of the converter may be reduced. An inkjet recording device in which the amount of displacement of the electromechanical transducer is reduced reduces the droplet ejection performance, that is, the droplet ejection speed and the size of the ejected droplets, resulting in a decrease in print density and image recording. The quality of images may deteriorate or highly accurate image recording may not be possible.

To give a specific example, a device consisting of the above configuration is 130
After being left in a temperature environment of °C for one month, the droplet ejection speed decreased to about 80% of the initial ejection speed. In addition, the inkjet recording device that had been left at an environmental temperature of 60°C was moved to an environmental temperature of -3.0°C and left for 4 hours.
If one unit is then moved to an environmental temperature of 60°C and left for 4 hours, measure the ejection speed of the droplet after repeating this for 6 units, that is, after applying thermal shock 12 times. did. As a result, in the conventional inkjet recording apparatus, the ejection speed decreased to about 65% of the initial ejection speed due to the thermal shock as described above.

Furthermore, when recording was performed using each device in which the ejection speed of droplets was reduced, a decrease in recording density was observed as the ejection speed decreased, and the image quality deteriorated.

〔the purpose〕

The present invention causes deterioration in the quality of recorded images. It is an object of the present invention to provide an inkjet recording device that can prevent a decrease in the amount of mechanical displacement due to changes over time in an electromechanical converter and can record high-quality images regardless of the environment in which the device is placed.

An object of the present invention is to provide an inkjet recording device equipped with an electro-mechanical converter that generates energy for forming flying droplets, in which a DC voltage is applied in a direction that strengthens the polarization of the converter of the electro-mechanical converter. This is achieved by having a means for applying .

〔Example〕

The present invention will be explained using preferred embodiments.

FIG. 1 is a schematic cross-sectional view of the recording head of the inkjet recording apparatus used in this example.

FIG. 1 shows an example in which a cylindrical piezoelectric element is used as an electromechanical transducer 11 that generates energy for ejecting droplets from an orifice. Also, in Figure 1, 12
13 is an adhesive for bonding the converter 11 and the nozzle 12, and 14 is energy in the direction of ejecting droplets when the converter 11 is driven. This is a filter for adjusting the balance of energy in the direction of liquid supply and/or preventing impurities from entering the nozzle, and adjusting the flow rate of liquid supply.

In the recording head shown in FIG. 1, the feeder 14 side of the recording head is immersed in the liquid in the sub-tank 21, as shown in the schematic cross-sectional view of the area around the recording head of an inkjet recording apparatus in FIG. It is installed. Further, 22 is a supply tube for supplying liquid into the sub-tank 21 connected to a main tank (not shown), and 23 is a suction tube for adjusting the liquid level in the sub-tank 21.

FIG. 3 is a circuit diagram showing an example of a drive circuit for driving the converter 11 of the inkjet recording apparatus. In FIG. 3, 31 is a converter, and 32 is the converter 3.
1 is a power input terminal for driving the 1, 33 is a pulse input changeover switch, 34 is a resistor for changing the voltage applied to the converter 31, and 35 is an ejection terminal for manually applying pulses for ejecting droplets. The pulse trigger is one input terminal.

What is shown in FIG. 4 is a waveform diagram showing an example of the waveform of the input pulse inputted to each electrical/mechanical converter, and (a) is a waveform diagram of one example of the ejection pulse.

(b) is a trigger waveform diagram of a repolarization pulse. FIG. 5 is a waveform diagram showing an example of the voltage waveform of the voltage input to the electrical/mechanical converter, respectively. (a) is a voltage waveform diagram of the ejection pulse, and (b) is a voltage waveform diagram of the repolarization pulse. be.

In the present invention, by applying a voltage of opposite polarity to the electro-mechanical converter at any time during non-image recording (that is, a voltage in the direction in which the electro-mechanical converter is polarized) to that during image recording, To maintain good performance of an inkjet recording device.

An example of how voltage is applied to the electromechanical converter during image recording and repolarization in the present invention will be explained using FIGS. 3 to 5.

Normally, an ejection signal is input to the tri-force input terminal 35 of the ejection pulse shown in FIG. 3, and a desired voltage is applied to the converter 31, thereby causing the converter 31 to be mechanically displaced. During repolarization, a repolarization signal is input to the input terminal 36 in response to a repolarization pulse. As a result, a voltage having a polarity opposite to that during recording is applied to the converter 31. In addition, converter 3
The voltage input to the terminal 1 can be easily changed by changing the voltage input to the terminal 35 or the terminal 36 or by changing the resistance 34.

In this example, a recording head having a configuration as shown in FIG.
After ZT (lead zirco-t 1 tanate) was bonded, a filter 14 was attached to the liquid inflow side of the nozzle 12 for use. This recording head is then
As shown in the figure, an inkjet recording device was prepared by immersing the filter 14 side into the subtank 21.

After measuring the initial ejection speed of droplets and the initial dot diameter on paper of the inkjet recording device (hereinafter abbreviated as the device) prepared as described above, it was left in a temperature environment of -30° C. for one month.

Thereafter, the apparatus was returned to room temperature, and DC power was applied to the droplet strand electric/mechanical converter in a direction that strengthened the polarization of the converter (again) in the same way as when measuring the initial discharge rate and initial dot diameter on paper. After applying a polarization pulse, the ejection speed of the droplet and the diameter of the dot on the paper were measured. The results are shown in Table 1 for the droplet ejection speed and Table 2 for the dot diameter on paper.

Table 1 Table 2 The ejection speed of droplet and the diameter of one dot on paper are as follows: input voltage 70
This is the value when a rectangular voltage of V is input. Further, as a repolarization pulse, a rectangular voltage with an input terminal of -90V and a pulse width of 1 minute was manually applied.

As can be seen from Tables 1 and 2, the droplet ejection speed of the device left in a -30°C temperature environment for one month decreased significantly compared to the initial stage. Similarly, the dot diameter was significantly smaller than the initial value.

When an image was actually recorded using the apparatus in this state, only an image with reduced image density was obtained, and the recording was clearly inferior to the initial image. On the other hand, with the device of the present invention in which a repolarization pulse was applied, there was almost no change in the initial droplet ejection speed and dot diameter on paper, and the recorded image was also comparable to the initial device. .

As another example of the present invention, a repolarization pulse was applied while the device was left in a -30°C temperature environment and compared with the initial state. In this case as well, the recorded image was I was able to obtain something that was completely comparable to the others.

The pulse width of the repolarization pulse is preferably equal to or greater than the pulse width of the ejection pulse, but more preferably 10 seconds or more in order to obtain a sufficient repolarization effect, and optimally 10 seconds in consideration of the time when the device is not used. It is best to set it to 1 minute.

It is preferable to use a voltage with opposite polarity that is equal to or greater than the voltage applied when printing a repolarization pulse, and its northern limit should be set at a voltage that may cause damage to the electromechanical transducer, taking into account the time during which the repolarization pulse is applied. Of course, it is set so that it does not exist.

The repolarization pulse does not necessarily need to consist of one pulse, and a plurality of short pulses may be input in succession.

In this case, the repolarization pulse referred to in the present invention may be considered as a collection of a plurality of short pulses.

Furthermore, it goes without saying that the voltage waveform does not have to take the shape shown in FIG. 5(b).

Although it is necessary that the repolarization pulse be applied when the apparatus is not recording an image, it may be applied at any time as long as the conditions are met. For example, the repolarization pulse may be applied by the user of the apparatus or at any time during non-image recording using means such as a switch, relay, or switching circuit. Alternatively, when the power is turned on to the apparatus, when a droplet ejection recovery operation is performed, or when the apparatus is equipped with an ink temperature compensation mechanism such as a heater, when the compensation mechanism is activated, for example, the above-mentioned means can be used to restart the ink temperature for a desired time. A polarization pulse may also be applied. The latter case is preferable in that it always avoids erroneous operations by the user and recording of defective images.

Effects> As explained in detail above, according to the present invention, in an inkjet recording device using an electro-mechanical converter, stable image recording can be performed at all times regardless of the temperature environment in which the device is placed. An inkjet recording device is provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the recording head of an inkjet recording device, FIG. 2 is a schematic cross-sectional view of the inkjet recording device, and FIG. Figure 4 is a waveform diagram showing an example of the waveform of the input pulse, (a) is the waveform diagram of the ejection pulse, (b) is the waveform diagram of the repolarization pulse, and Figure 5 is the waveform diagram of the voltage manually applied to the electromechanical converter. In the voltage waveform diagrams showing an example of waveforms, (a) is a voltage waveform diagram during image recording, and (b) is a voltage waveform diagram during p-p polarization. 11...Electrical/mechanical converter (converter). 12...Liquid flow path forming member (nozzle). 13... Adhesive, 14... Filter. 21...Subtank, 22...Supply tube. 23...Suction tube. Procedural amendment (voluntary) July 2, 1985 Michibe Uga, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 82608 of 19822, Name of the invention Inkjet recording device3, Person making the amendment Case and Relationship Patent applicant address 3 = 30-2 Shimomaruko, Ota-ku, Tokyo Name (100
)Representative of Canon Co., Ltd. Iwakaki Han 3 Department 4, Agent address: 3-30-25 Shimomaruko, Ota-ku, Tokyo 148, Specification subject to amendment 6, Contents of amendment (1) Specification, Page 7, No. 3 In the line ``with the opposite polarity'' is corrected to ``with the same polarity as''. (2) On page 7, line 16 of the specification, "the opposite polarity to" is amended to "the same polarity to". (3) Specification section page 11, line 4 r-90VJ to r90V
Correct it with J. (4) Correcting "reverse polarity of F in page 12, line 10 of specification" to "same polarity of"

Claims (1)

[Claims] In an inkjet recording device equipped with an electro-mechanical transducer that generates energy for forming flying droplets,
An inkjet recording apparatus characterized by having a Jtlt means for applying a DC voltage to the electromechanical converter in a direction that strengthens the polarization of the converter.