JP2001080062A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a discharge efficiency by applying pulses not to discharge ink and to heat to channels which are not to discharge ink, holding a head temperature to be higher than a room temperature at all times, and eliminating a temperature difference and an ink viscosity variation when the apparatus drives. SOLUTION: An ink-jet recording head has a plurality of channels 2 parallel to each other and separated by piezoelectric ceramics diaphragms 3. The diaphragm 3 is deformed corresponding to a voltage impressed to a signal electrode formed to an inner wall of the channel, whereby the ink filled in the channel is selectively discharged from an ink discharge port communicating to the channel. A thermistor for temperature detection is set to the vicinity of an actuator of the head. A pulse voltage unrelated to the discharge is impressed to the electrode to an upper limit of a target set temperature. The impression is stopped to reach a lower limit when the upper limit is exceeded. A temperature of the head is thus kept in a stable set temperature higher than a room temperature by a control means, so that a stable discharge performance is effectuated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of parallel channels separated by a partition made of piezoelectric ceramics, and the partition is formed in accordance with a voltage applied to a signal electrode formed on an inner wall of the channel. The present invention relates to an ink jet recording apparatus (international patent classification B41J 3/10) equipped with an ink jet recording head which deforms and causes the ink filled in the channel to selectively protrude from a nozzle connected to the channel with the deformation. In this case, the ink can always be stably ejected.

[0002]

2. Description of the Related Art As a conventional example of such a recording method, an ink jet recording apparatus utilizing shear mode deformation of a piezoelectric element as an ink ejection principle has been considered as disclosed in Japanese Patent Application Laid-Open No. 63-252750. As shown in FIG. 2, this configuration mainly includes an actuator member 9 made of piezoelectric ceramics, a top sheet 6, a nozzle plate 7, and a printed wiring board 1. Actuator member 9
Is formed with a plurality of channels 2 cut by a diamond blade or the like. The partition walls 3 between the channels 2 are subjected to polarization processing in the groove depth direction.

The channels 2 have the same depth and the same groove width, and are parallel to each other. The depth of the channel 2 is gradually reduced as approaching the rear end face of the actuator member 9, and the channel 2 is located near the rear end face. 2 shallow regions are formed. The signal electrodes 4 are formed on the upper halves of both sides of each channel 2 by sputtering or vapor deposition.

In the shallow region of the channel 2, signal electrodes 4 are similarly formed on the side and bottom surfaces by sputtering or vapor deposition. This makes channel 2
Are electrically connected by the signal electrodes 4 formed on the bottom surface of the shallow region of the channel 2.

Next, the top sheet 6 is formed of a ceramic material or a resin material. In addition, the ink supply port 5 and a manifold (not shown) are formed in the top sheet 6 by grinding or cutting.
Then, the processing-side surface of the channel 2 of the actuator member 9 and the processing-side surface of the manifold of the top sheet 6 are bonded by an epoxy-based adhesive (not shown).
In this way, the ink-jet head is configured with a plurality of channels 2 as a plurality of ink channels having the same spacing in the horizontal direction by covering the upper surface of the channel 2. The channels 2 have an elongated shape with a rectangular cross section, and all the channels 2 are filled with ink from the ink supply ports 5.

A nozzle plate 7 is adhered to the end surfaces of the actuator member 9 and the top sheet 6 such that the nozzle 8 is located at a position corresponding to the position of each channel 2. The nozzle plate 7 is formed of a plastic such as polyimide, polyetherimide, polyetherketone, polyethersulfone, and polycarbonate. The nozzle plate 7 is attached to the ink ejection surface side of the actuator member 9 and the top sheet 6 using an epoxy adhesive or the like, and then the center of each channel 2 is positioned by a microscope or the like, and then an apparatus such as an excimer laser is used. Drilling holes.

The printed wiring board 1 is adhered to the surface of the actuator member 9 opposite to the channel 2 with an epoxy adhesive or the like. A conductive pattern 11 is formed on the printed wiring board 1 at a position corresponding to the position of each channel 2. The conductive pattern 11
And the signal electrode 4 formed on the bottom surface of the shallow region of the channel 2
Are connected by a bonding wire 10.

This ink jet recording head has a plurality of parallel channels 2 separated by a partition 3 made of piezoelectric ceramics, according to a voltage applied to a signal electrode 4 formed in an inner wall partition 3 of the channel 2. Then, the partition wall 3 is deformed, and the ink filled in the channel 2 is deformed by the deformation.
Recording is possible by selectively discharging from the nozzles 8 communicating with the nozzles. FIG. 3 shows a driving waveform for applying the applied voltage. The illustrated drive waveform is one of the waveforms that can eject one drop of ink.

[0009]

However, in the above-described conventional configuration, when the ink jet recording head is driven, the piezoelectric ceramic generates heat due to the applied energy, and the temperature of the head itself rises, and the temperature difference in the head is increased. Occurs. In a portion where the temperature is high, the viscosity of the ink tends to decrease, and the ejection speed of the ink tends to be higher than in other portions. As a result, dot position accuracy has deteriorated, which has been one of the causes of deterioration of recording quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus having a stable ink discharge performance in consideration of such problems of the conventional ink jet recording head.

[0011]

In order to solve the above-mentioned problems, an ink jet recording apparatus according to the present invention applies a pulse irrelevant to ink ejection to a channel that does not eject ink so that heat is generated. By applying the applied energy, the temperature of the head is always maintained at a temperature higher than room temperature, eliminating the temperature difference at the time of driving the head, preventing the ink viscosity from changing, and stabilizing the ink ejection performance. To solve the above problem. Further, as the size of the head increases, the rate of temperature rise differs depending on the position. Therefore, the inkjet recording apparatus can maintain the temperature of the head constant by controlling and giving the number of pulses for each channel.

That is, the ink jet recording apparatus of the present invention is capable of controlling the temperature of the ink jet recording head for selectively discharging ink by applying a pulse signal.
It is characterized by operating at a temperature higher than the operating environment temperature, and stably operating at a temperature higher than the ambient temperature even when the ambient temperature changes and the temperature inside the head greatly differs. It is to realize that.

Further, the ink jet recording apparatus of the present invention comprises the ink jet recording head, a drive waveform output device for driving the ink jet recording head, a detecting means for detecting the temperature of the ink jet recording head, and the ink jet recording head. Means for setting the target temperature of the ink jet recording head by applying a pulse irrelevant to ink ejection, in addition to the ejection waveform and the non-ejection waveform, in addition to the ejection waveform and the non-ejection waveform. A means for controlling the target temperature is provided, and even when the ambient temperature changes and the temperature inside the head is greatly different, the head generates heat by applying a pulse irrelevant to ink ejection, This realizes stabilization at a temperature higher than the ambient temperature.

Further, the ink jet recording apparatus of the present invention is characterized in that the number of pulses irrelevant to the ejection of ink to be applied to the ink jet recording head is applied by changing the number of pulses for each channel. Even if the position differs depending on the position, the operation can be stably performed at a temperature higher than the ambient temperature.

In the ink jet recording apparatus of the present invention, there are provided a plurality of detecting means for detecting the temperature of the ink jet recording head, and the number of pulses irrelevant to the ejection of the ink is determined for each detected temperature. , And means for controlling the target temperature.Even when the ambient temperature changes and the temperature in the head is different, the number of pulses irrelevant to ink ejection is increased. By giving and controlling for each channel of
This realizes stabilization at a temperature higher than the ambient temperature.

Also, in the ink jet recording apparatus of the present invention, the ink jet recording head has a plurality of parallel channels separated by a piezoelectric ceramic partition, and applies the voltage to a signal electrode formed on the inner wall of the channel. An ink jet recording head that deforms the partition wall according to a voltage and selectively discharges ink filled in the channel from an ink discharge port communicating with the channel according to the deformation.

According to the present invention, even if the ambient temperature of the head changes due to a change in room temperature or the like, the temperature of the head is kept constant by changing the number of pulses irrelevant to the ink ejection, and the viscosity of the ink is maintained. It is possible to prevent the change from occurring and to stably eject the ink.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) An embodiment of the present invention described in claims 1, 2, 3, and 4 will be described below with reference to FIG. Components that are substantially the same as those in the conventional example shown in FIGS. 2 and 3 are denoted by the same reference numerals.

FIG. 1 shows a driving waveform of the ink jet recording head of the present invention. This drive waveform is different from the drive waveform of the conventional inkjet recording head shown in FIG. 3 in that one or more pulses 13 small enough not to eject ink are applied after the original ejection pulse and the non-ejection pulse 12. It is. With this drive waveform, a small pulse 1
Since sufficient heat energy can be obtained regardless of whether or not ink is actually ejected by the heat generated by the applied energy of 3, it is possible to use the heat generated by the head to make the temperature of the head constant at a temperature higher than the ambient temperature. Will be possible.

Here, if the number of pulses 13 that does not cause the ink ejection is the same for all channels,
Since both ends are cooled by the peripheral temperature than the central part of the head, the temperature of the head may be uneven. Therefore, in order to keep the temperature of the head constant, the number of pulses 13 irrelevant to ink ejection applied to each channel is changed, that is, the number of pulses 13 irrelevant to ink ejection is reduced at the center of the head, By increasing the number of pulses 13 irrelevant to ink ejection toward both ends, the temperature of the head is kept constant at a temperature higher than the surrounding temperature, and the recording quality is improved.

Next, the structure of the ink jet device will be described.

A thermistor, which is a means for detecting the temperature, is mounted near the actuator section of the ink jet recording head, and a pulse 13 irrelevant to the ejection is given until the upper limit of the target set temperature is reached.
Until the lower limit of the target set temperature is reached, the application of the pulse 13 unrelated to ejection is stopped. By having such control means, it is possible to drive the ink jet recording apparatus within the set temperature.

Here, a plurality of thermistors are attached to the ink jet recording head, and a pulse 13 irrelevant to ejection is given until the detected temperature of each thermistor reaches the upper limit of the target set temperature. By changing the number of pulses 13 irrespective of the magnitude of the temperature difference and unrelated to ejection, the temperature inside the head can be set to the target set temperature. When the upper limit of the target set temperature is reached, the number of pulses 13 unrelated to ejection is changed to one or zero, and the temperature is set lower than the upper limit of the target set temperature. With such control means, it is possible to drive the ink jet recording apparatus at a lower set temperature than the control means.

[0024]

As described above, according to the method of driving the ink jet recording head of the present invention, the head temperature is always kept constant at a temperature higher than room temperature due to the heat generated by the applied energy of the driving portion of the head. Is also constant, the ink ejection performance is stabilized. Further, the recording quality is improved by stabilizing the ink ejection performance.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating driving waveforms of an inkjet recording head according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of a conventional inkjet recording head.

FIG. 3 is a diagram illustrating a driving waveform of a conventional inkjet recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Channel 3 Partition wall 4 Electrode 5 Ink supply port 6 Top sheet 7 Nozzle plate 8 Nozzle 9 Actuator member 10 Bonding wire 11 Conductive pattern 12 Ink discharge pulse 13 Pulse unrelated to ink discharge

Continuing on the front page (72) Koji Sone, an inventor at Koshincho, Takamatsu-shi, Kagawa Prefecture, 1-8 Matsushita Hisashi Denshi Kogyo Co., Ltd. Incorporated F term (reference) 2C056 EA04 EB07 EB30 EC07 EC29 EC38 FA04 2C057 AF29 AG45 AL25 AM16 BA03 BA14 2C062 AB13

Claims (6)

[Claims] 1. An ink jet recording apparatus for selectively discharging ink, wherein a pulse for not discharging ink is given to a channel which does not discharge ink so that the temperature of the ink jet recording head becomes lower than room temperature. An ink jet recording apparatus which is maintained at a high temperature and is operated at a temperature higher than a use environment temperature. 2. An ink jet recording head; a driving waveform output means for outputting a driving waveform for driving the ink jet recording head; a detecting means for detecting a temperature of the ink jet recording head; and setting a target temperature of the ink jet recording head. Setting means for controlling the temperature of the ink jet recording head to a target temperature using the detecting means and the setting means, wherein the drive waveform output means discharges ink for discharging ink. An ink jet recording apparatus that generates a pulse drive waveform that does not discharge ink, in addition to a waveform and an undischarged waveform. 3. The ink jet recording apparatus according to claim 1, wherein the number of pulses to be applied to the ink jet recording head for not discharging ink is changed for each channel and applied. 4. The apparatus according to claim 1, wherein a plurality of said detecting means are provided, and the number of pulses for which said ink is not ejected is changed in accordance with each detected temperature to control the target temperature at all positions. The ink jet recording apparatus according to claim 2, wherein 5. The ink jet recording head has a plurality of parallel channels separated by a piezoelectric ceramic partition, and deforms the partition according to a voltage applied to a signal electrode formed on an inner wall of the channel. The ink jet recording head according to any one of claims 1 to 4, wherein said ink jet head selectively discharges ink filled in said channel from an ink discharge port connected to said channel. The inkjet recording apparatus according to any one of the preceding claims. 6. An ink jet recording apparatus for selectively discharging ink, wherein a pulse which does not discharge ink is given to a channel which does not discharge ink, thereby averaging the temperature distribution of the ink jet recording head. An inkjet recording apparatus.