JPH07137276A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To detect an ink holding amount in an ink tank by providing holding amount detecting means for detecting an electric signal of a piezoelectric vibra tor mounted in the tank or its variation amount of detect the ink holding am ount in the tank. CONSTITUTION:A piezoelectric vibrator 1 utilizes so-called secondary piezoelectric effect generated when a strain occurs by applying an electric field to a certain ionic crystal. If an ink tank 2 contains a predetermined quantity of ink 3, they have predetermined natural frequencies. When a voltage is varied to approximate a frequency of the vibrator to the natural frequency of the tank 2, it is resonated. When this resonation is detected by a Q meter, etc., a quantity of the ink 3 can be detected. The natural frequency of each vibration system is varied according to the quantity of the ink 3 in the tank 2. Generally, the less the quantity of the ink 3 is, the higher the natural frequency becomes. When correlation between the resonance of the meter and the ink amount by monitoring a frequency at the time of resonance is obtained, the tank 2 interior can be arbitrarily monitored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus having a recording head (hereinafter also referred to as a head) for generating recording liquid droplets used in an inkjet recording system.

[0002]

2. Description of the Related Art The basic structure of an ink jet recording apparatus applied to an ink jet recording system (liquid jet recording system) is such that a fine ink ejection port, an ink liquid flow path and the liquid flow path for ejecting ink droplets. A head substrate body including an ink ejection energy generating element provided in a part of the head substrate, a member for holding the substrate, a head including three components of a member for supplying electric energy to the head substrate, and It is composed of an ink supply member for supplying ink to the head, and an ink tank provided on the head side for temporarily holding ink for supplying ink to the head. The ink is supplied to the head in the order of the ink tank, the ink supply member, and the head body. In an inkjet recording apparatus, controlling the amount of ink supplied to the head body is important for ensuring long-term stability of the head. Also, from the standpoint of using the head, it is important in terms of reliability that the remaining amount of ink is constantly monitored.

Conventionally, as a method of monitoring the ink holding amount, there is a method in which an electrode is provided in an ink tank and a constant voltage is applied to the electrode. By making the ink conductive, a constant current flows when the ink is present in the ink tank. When the ink in the tank is exhausted, the current stops flowing. By utilizing this fact, the presence or absence of ink can be detected.

[0004]

However, in this conventional method, the presence or absence of ink can be detected, but the amount of ink itself cannot be known. In an inkjet recording apparatus, controlling the amount of ink supplied to the head body, and detecting and controlling not only the presence / absence of ink in the ink tank but also the amount of ink retained in the inkjet recording apparatus can improve the long-term stability of the inkjet recording apparatus. Is important for ensuring reliability.

It is an object of the present invention to provide an ink jet recording apparatus capable of detecting the amount of ink held in the ink tank itself.

[0006]

An ink jet recording apparatus of the present invention is an ink jet recording apparatus having a recording head for ejecting ink and an ink tank for holding a certain amount of ink to be supplied to the recording head. Alternatively, a plurality of piezoelectric vibrators may be attached to the ink tank, and an ink holding amount detection unit for detecting the amount of ink in the ink tank by detecting an electric signal of the piezoelectric vibrator or a change amount thereof may be provided. Characterize.

According to the present invention, the electric signal may have a frequency of an AC component or an amplitude of an AC component.

[0008]

By detecting the electric signal of the piezoelectric vibrator attached to the ink tank or the amount of change in the electric signal, the natural frequency of the ink tank can be monitored. Generally, the smaller the amount of ink, the higher the natural frequency of the ink tank. By correlating the natural frequency with the ink amount, the ink amount in the ink tank can be monitored at any time.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a principle diagram of a method for detecting the ink amount in an ink tank according to a first embodiment of an ink jet recording apparatus of the present invention, FIG. 1A is a diagram showing a case where the ink amount in the tank is large, (B) is a diagram showing a case where the amount of ink in the tank is small.

The piezoelectric vibrator 1 utilizes a so-called secondary piezoelectric effect, which causes distortion when an electric field is applied to a certain ionic crystal. Electric polarization P and stress X of piezoelectric crystal due to electric field
Is expressed by the piezoelectric coefficient d. The piezoelectric coefficient is a value unique to each substance. The relationship is represented by P = ΣdX. From this equation, the magnitude of stress changes depending on the magnitude of the applied electric field. That is, it corresponds to a change in frequency. On the other hand, as shown in FIGS. 1A and 1B, the ink tank 2
When there is a fixed amount of ink 3 in each, each system has a fixed natural frequency. Here, if the frequency of the piezoelectric vibrator is made to approach the natural frequency of the ink tank 2 by varying the voltage, resonance occurs. The amount of the ink 3 can be detected by detecting this resonance phenomenon with a Q meter or the like. The natural frequency of each vibration system changes depending on the amount of ink 3 in the ink tank 2. In general, the smaller the amount of ink 3, the higher the natural frequency. The amount of ink in the ink tank 2 can be monitored at any time by detecting the resonance by the Q meter and monitoring the frequency (frequency) at the time of resonance and correlating it with the amount of ink.

The ink amount detection device according to the present invention is established even if the frequency of the piezoelectric vibrator does not necessarily completely match (ie, resonate with) the natural frequency of the system. Even if they do not resonate, each vibration system vibrates at a certain frequency. As shown in FIG. 2, this is realized by connecting a resonance circuit to the reception vibrator 4 separately from the power supply circuit of the piezoelectric vibrator 1 and finding the resonance point. In this case, a fixed voltage may be applied to the piezoelectric vibrator 1 and the resonance point may be found by, for example, a variable capacitor of the resonance circuit. Here, the scale of the variable condenser and the amount of ink have a linear relationship. Of course, a variable coil can be used.

Further, if the piezoelectric vibrator can be attached, there is no restriction on the material and shape of the ink tank. Further, regarding the ink, there is no problem even if it is a material that solidifies when the temperature decreases, such as solid ink.

FIG. 5 is an external perspective view showing an example of an ink jet recording apparatus (IJRA) in which the recording head obtained by the present invention is mounted as an ink jet head cartridge (IJC).

In FIG. 5, reference numeral 20 denotes an ink jet head cartridge (IJC) provided with a group of nozzles for ejecting ink so as to face the recording surface of the recording paper fed onto the platen 24. Reference numeral 16 is a carriage HC that holds the IJC 20, and is connected to a part of a drive belt 18 that transmits the driving force of the drive motor 17, and is slidable with two guide shafts 19A and 19B arranged in parallel with each other. By doing so, reciprocating movement over the entire width of the recording paper of the IJC 20 is possible.

Reference numeral 26 denotes a head recovery device, which is an IJC20.
Is arranged at one end of the movement path of, for example, at a position facing the home position. The drive force of the motor 22 via the transmission mechanism 23 causes the head recovery device 26 to operate, and
Cap the JC20. This head recovery device 2
In association with capping of the IJC 20 by the cap portion 26A of No. 6, ink is sucked by an appropriate suction means provided in the head recovery device 26 or ink is pressure-fed by an appropriate pressure means provided in an ink supply path to the IJC 20. The ejection recovery process such as removing the thickened ink in the nozzle by forcibly ejecting the ink from the ejection port is performed. Further, the IJC is protected by capping at the end of recording or the like.

Reference numeral 30 is a blade as a wiping member which is disposed on the side surface of the head recovery device 26 and is made of silicon rubber. The blade 30 is a blade holding member 30.
The head recovery device 26 is held by A in a cantilever form.
Similarly to the above, the motor 22 and the transmission mechanism 23 operate to enable engagement with the ejection surface of the IJC 20. As a result, the blade 30 is projected into the movement path of the IJC 20 at an appropriate timing in the recording operation of the IJC 20 or after the ejection recovery process using the head recovery device 26, and the ejection surface of the IJC 20 is moved along with the movement operation of the IJC 20. It wipes off condensation, wetness, dust, etc.

Next, the present invention will be described in more detail with reference to experimental examples.

[Experimental Example 1] An experimental example 1 will be described with reference to FIGS. 1 and 3. In this experimental example, the detected amount is shown in FIG.
The change in the amplitude of the voltage output from the piezoelectric vibrator 1 is used. The ink tank 2 used in this experimental example is a box-shaped ink tank made of Al. Although the ink tank 2 is provided with a lid, it is omitted in the figure. As the piezoelectric vibrator 1, a surface mount compatible crystal vibrator MA-406 manufactured by Seiko Epson Corporation was used. This oscillator has a wide frequency adaptive range and a wide range of applicable sizes of the ink tank 2. Although the mounting position of the piezoelectric vibrator 1 is shown as the bottom surface of the ink tank 2 in the drawing, it may be of course another position. Although MA-406 was used in this experimental example, other selections are necessary depending on the size of the ink tank 2. Although the case of using the Q meter has been described in the explanation of the principle, in the present experimental example, the piezoelectric vibrator 1 is oscillated in advance at a frequency close to or just the natural frequency of the ink tank 2.
Using the voltage (amplitude) applied to the piezoelectric vibrator 1 at that time as the initial value, the natural frequency of the ink tank 2 changes from f0 to f1 due to the decrease in the ink 3, the Q point shifts, and the voltage amplitude decreases. Was used (see FIG. 3).

[Experimental Example 2] In Experimental Example 2, the Q point was detected by the Q meter as the detection amount, and the frequency at that time was simultaneously recorded. Then, when the ink amount changes, the natural frequency of the ink tank 2 (see FIG. 1) changes, that is, the point Q changes, as shown in FIG. By correlating the frequency at each point with the ink amount, the ink amount can be monitored at any time. The actual device configuration is the same as in Experimental Example 1, but the detection amount is different.

[Experimental Example 3] An experimental example 3 will be described with reference to FIG. In this experimental example, two piezoelectric oscillators are used, one of which is used as the oscillator 5 for oscillation, and the other is used as the oscillator 4 for reception. In this experimental example, TCO-976 series manufactured by Toyo Communication Equipment Co., Ltd. was used as the oscillator 1 for transmission.
The frequency of this oscillator is fixed to four waves, but there is no problem in using it as in this experimental example. Receiving oscillator 4
MA-406 was used as in Experimental Example 1. Figure 2
As shown in FIG. 3, a resonance circuit is connected to the receiving oscillator 4, and a resonance point is searched for by a variable capacitor or the like to correlate with the ink amount in the ink tank 2, so that the ink amount can be monitored at any time. .

The present invention brings excellent effects particularly in an ink jet type recording head and a recording device which form flying droplets by utilizing thermal energy among the ink jet recording systems.

With regard to its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal converter arranged corresponding to the sheet or liquid path in which is stored, a rapid temperature rise corresponding to the recorded information and exceeding nucleate boiling is applied. , It is effective because it generates heat energy in the electrothermal converter, causes film boiling on the heat-acting surface of the recording head, and as a result, can form bubbles in the liquid (ink) that correspond one-to-one to this drive signal. Is. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose a configuration in which a heat acting portion is arranged in a bending region.

In addition, JP-A-59-123670, which discloses a structure in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and a pressure wave of thermal energy is absorbed. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration in which an opening corresponds to a discharge portion.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length can be increased by combining a plurality of recording heads as disclosed in the above-mentioned specification. The present invention can exert the above-mentioned effects more effectively, although it may have a configuration that satisfies the above requirement or a configuration as one recording head integrally formed.

In addition, by being mounted on the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. The present invention is also effective when a cartridge-type recording head provided with an ink tank is used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or sucking means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording It is also effective to perform stable recording.

Further, as the recording mode of the recording apparatus, not only the mainstream color such as black but not only the recording mode, the recording head may be integrally formed or a plurality of them may be combined. The present invention is also extremely effective for a device provided with at least one of full colors by color mixing.

In the embodiments of the present invention described above, the ink is described as a liquid, but it is an ink which solidifies at room temperature or lower and softens at room temperature, or a liquid, or the above-mentioned liquid. In the inkjet method, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. It may be in a liquid form.

In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy for changing the state of the ink from the solid state to the liquid state, or the ink is solidified in a standing state for the purpose of preventing evaporation of the ink. In some cases, such as ink that is liquefied by applying heat energy according to a recording signal and ejected as a liquid ink, or one that has already started to solidify when it reaches a recording medium. The use of an ink having a property of being liquefied only by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or JP-A-60-71260, a mode in which the porous sheet is opposed to the electrothermal converter in the state of being held as a liquid or solid in the recess or through hole of the porous sheet. May be In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as a form of the recording apparatus according to the present invention, in addition to one provided integrally or separately as an image output terminal of information processing equipment such as a word processor or a computer, a copying apparatus combined with a reader or the like, May take the form of a facsimile machine having a transmission / reception function.

[0034]

As described above, according to the present invention, the amount of ink in the ink tank can be monitored at any time by detecting the electric signal of the piezoelectric vibrator attached to the ink tank or the amount of change in the electric signal. Therefore, long-term stability and reliability of the inkjet recording device can be secured.

[Brief description of drawings]

FIG. 1 is a principle diagram of a method of detecting an ink amount in an ink tank according to a first embodiment of an inkjet recording apparatus of the present invention, FIG. 1A is a diagram showing a case where the ink amount in the tank is large, and FIG. ) It is a diagram showing a case where the amount of ink in the tank is small.

FIG. 2 is a principle diagram of a method for detecting an ink amount in an ink tank according to a second embodiment of an inkjet recording apparatus of the present invention.

FIG. 3 is a graph showing the natural frequency of the ink tank 2 detected in Experimental Example 1.

FIG. 4 is a graph showing the relationship between the ink amount detected in Experimental Example 2 and the natural frequency of the ink tank.

FIG. 5 is an external perspective view showing an example of an inkjet recording apparatus.

[Explanation of symbols]

 1 Oscillator for Oscillation 2 Ink Tank 3 Ink 4 Oscillator for Reception 16 Carriage 17 Drive Motor 18 Drive Belt 19A, 19B Guide Shaft 20 Inkjet Head Cartridge (IJC) 22 Cleaning Motor 23 Transmission Mechanism 24 Platen 26 Head Recovery Device 26A Cap Part 30 Blade 30A Blade holding member

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Genji Inada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsuhiro Shirota 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non non corporation

Claims (6)

[Claims] 1. An ink jet recording apparatus having a recording head for ejecting ink and an ink tank for retaining a certain amount of ink to be supplied to the recording head, wherein one or a plurality of piezoelectric vibrators are provided in the ink tank. An ink jet recording apparatus, characterized in that it has an ink holding amount detecting means which is attached and detects the amount of ink in the ink tank by detecting the electric signal of the piezoelectric vibrator or its change amount. 2. The ink jet recording apparatus according to claim 1, wherein the electric signal has a frequency of an AC component. 3. The ink jet recording apparatus according to claim 1, wherein the electric signal has an amplitude of an AC component. 4. The ink jet recording apparatus according to claim 1, wherein the recording head is a full line type in which ejection openings are formed over the entire width of a recording area of a recording medium. 5. The ink jet recording apparatus according to claim 1, wherein the recording head includes an electric machine heat conversion body for generating thermal energy for ejecting ink. 6. The ink jet recording apparatus according to claim 5, wherein the recording head ejects the ink from an ejection port by utilizing film boiling generated in the ink by thermal energy applied by the electric machine heat converter. Recording device.