JPH07323551A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To gradation record by controlling an ink discharge quantity and to homogeneously print by controlling the unevenness of a dot diameter in an ink jet recorder in which ink is boiled by alternately applying a voltage to the two electrodes and the ink is injected to print it. CONSTITUTION:A voltage is alternately so applied to a pair of electrodes 21, 22 made of conductive metal that the potentials to be applied to the electrodes 21, 22 become substantially symmetrical values at the positive and negative potential of ink 28, and the voltage value, the phase deviation and the voltage time width are altered, thereby controlling the ink discharge and the printing. Accordingly, since the ink discharge quantity can be freely changed, a gradation recording can be executed. The unevenness of the dot diameter of each nozzle and the change of the dot diameter due to aging change are fed back, thereby stably printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for forming flying droplets of ink for recording.

[0002]

2. Description of the Related Art As computers have become more sophisticated, smaller, and cheaper, printers are required to have the same characteristics, and models are being switched from conventional dot printers to laser printers and ink jet printers. .

There are various types of ink jet recording apparatus. One is a type in which ink is pushed out by deformation of a piezo-piezoelectric element, the other type is in which ink is boiled by thermal resistance heating by applying a direct current and the ink is discharged in alternate electrodes. The main method is a high-frequency heating method in which the ink is boiled to eject the ink.

The manufacturing method and construction of the ink boiling portion and the ink discharging portion of the recording head of the type in which the ink is boiled and discharged by the high frequency heating method by alternating electrode energization are as follows.

FIG. 10 and FIG. 11 are a sectional view, a plan view and a control method of the ink boiling portion and the ink discharging portion of the recording head. A conductive metal film is formed on a ceramic substrate 6 such as silicon or glass by a physical film forming method such as a vapor deposition method, a sputtering method or a plating method. This metal film is processed by a photolithography method to form a pattern on each of the lead portion 3 and the electrode portions 1 and 2, and the portions other than these shapes are removed by ion milling or chemical etching. At this time, the electrode parts 1 and 2 and the lead part 3 are integrated. An insulating film 4 composed of an organic material, ceramics or the like is uniformly formed on the lead portion 3, the electrode portions 1 and 2 and the substrate 6 by coating or sputtering, and the electrode portions 1 and 2 are formed.
The insulating film 4 corresponding to is removed again by photolithography to expose the electrode portions 1 and 2. The tip of the lead portion 3 opposite to the electrode portions 1 and 2 side is provided with a contact with a flexible terminal so that a driving voltage from the outside is loaded, and the electrode portions 1 and 2 are in contact with the ink 8 at the opening portion 5. , Boil the ink 8. Further, the nozzle 9 is provided on the lead portion 3 and the insulating film 4 at a position substantially coincident with the positions of the electrode portions 1 and 2.
A sheet 7 of organic material or the like having an opening is adhered.

The operating principle of boiling is that both electrode parts 1, 2
When an alternating voltage of high frequency is applied to the electrolyte, the electrolyte present in the ink 8 vibrates and the boiling occurs together with the generation of Joule heat. In FIG. 10, 11 is an energization switching means, 10 is a power source, and the electrode parts 1 and 2 are energized via wiring 12. Due to the generation and expansion of the boiling bubbles, the ink 8 in the ink chamber is pushed up, and the nozzle 9 provided at the tip end.
The droplets of the ink 8 are caused to fly. The alternating voltage energization time is set to be longer than the maximum time required for ink boiling to occur, and one dot of ink is ejected during this period. Further, the frequency of the alternating voltage energization is selected so as to match the frequency of ink dot flight according to the resolution, which is the print quality.
The repeated life of ink boiling and ink ejection is usually guaranteed at tens of millions of times for the cartridge type in which the recording head and the ink container are integrated, and at hundreds of millions of times for the permanent type in which the recording head is installed in the printer body.

Conventionally, the method of applying the alternating voltage to the electrode portions 1 and 2 has been as shown in FIG. 12, FIG. 13 or FIG. In the system of FIG. 12, the maximum voltage V _max and the minimum voltage −V _max are applied to one electrode portion 1 at each time interval T, and at the same time, the minimum voltage −V _max and the maximum voltage V _max are applied to the other electrode portion 2. Similarly, the voltage is applied at every time interval T so that one electrode portion 1 is always and alternately 2 times more than the other electrode portion 2.
The value was increased by the value of × V _max . By repeatedly applying the voltage for a predetermined time, the boiling and the ink ejection are performed once. In the system of FIG. 13, the ground potential V ₀ and the maximum voltage V _max are applied to one electrode portion 1 at time intervals T, and at the same time, the maximum voltage V _max and the ground potential V ₀ are simultaneously applied to the other electrode portion 2. The voltage is applied at intervals T so that one electrode portion 1 is always and alternately higher than the other electrode portion 2 by the value of the maximum voltage V _max . Further, in FIG. 14, one electrode portion 1 always maintains the ground potential V _0, and the voltage of the other electrode portion 2 alternates between the maximum voltage V _max and the minimum voltage −V _max. The potential difference was always set to the maximum voltage V _max .

[0008] In these methods, by applying a set voltage value within a set time, a constant energy is supplied, and a substantially constant ink discharge amount is secured.

[0009]

However, in the conventional method as described above, gradation recording is performed by changing the ink ejection amount, or feedback is applied when the ink ejection amount varies for some reason. It was not possible to secure a stable discharge amount.

The present invention solves such a problem and provides an ink jet recording apparatus for obtaining gradation recording and homogeneous image recording.

[0011]

In order to solve the above problems, the present invention provides a method of changing the ink ejection amount by increasing or decreasing the voltage applied between the electrode portions, or a pair of electrode portions. The voltage is independently applied to each of the electrode portions of the ink, and the ink is heated by a means in which the potential changes of positive / negative or positive / zero or negative / zero with respect to the ground potential are repeated with substantially the same period, and By ejecting ink by adjusting the ratio of the time length in which the potential difference applied between the electrode parts is positive / negative and negative / positive and the time length in which the potential is equal, by shifting the time repetition of two voltage changes. A method of changing the amount, or a voltage applied independently to each electrode of a pair of electrode parts is a time with substantially the same cycle of potential change of positive / negative or positive / zero or negative / zero with respect to the ground potential. The ink is heated by the repeating means, and the positive and negative time widths of the two voltage changes are increased or decreased to increase or decrease the potential difference applied between the electrode portions. It is provided with a method of changing the ink ejection amount by adjusting the ratio of the positive time length and the equipotential time length.

[0012]

According to the present invention, the energy supplied between the electrode portions for ejecting ink can be increased or decreased by the above-mentioned means, so that the ink ejection amount can be freely increased or decreased.

[0013]

1 and 2 are a sectional view and a plan view showing an ink jet recording apparatus according to an embodiment of the present invention.

In this embodiment, a glass substrate is used as the substrate 26, and a conductive metal film made of titanium is formed on the substrate 26 by the sputtering method. As the sputtering conditions, the pressure inside the vacuum device when introducing argon gas, the substrate temperature during sputtering film formation, the power applied to the cathode target material, etc. are selected as parameters, and the optimum characteristics for the electrode part of the inkjet recording device are selected. Selected conditions for having. Next, each of the lead portion 23 and the electrode portions 21 and 22 was patterned on the metal film by a photolithography technique. Specifically, a photosensitive resin is applied on a titanium film sputter-deposited, and a chrome plate in which the shapes of the lead portion 23 and the electrode portions 21 and 22 prepared in advance are hollowed out is placed thereon and exposed to ultraviolet rays. To do. Lead portion 23,
The exposed resin other than the electrode portions 21 and 22 is removed by chemical etching. Further, this is chemically etched with a solvent that dissolves titanium to remove all titanium except the lead portion 23 and the electrode portions 21 and 22. Next, this is covered with an insulating resin to form an insulating film 24 on the electrodes 21 and 22 and the vicinity thereof. In particular,
An insulating photosensitive resin is uniformly spin-coated on the lead portion 23, the titanium films of the electrode portions 21 and 22 and the substrate 26,
The opening 25 is exposed to ultraviolet rays using another chromium mask plate, and this portion is removed by chemical etching. In this embodiment, the thickness of the electrode portions 21 and 22 is 1 μm,
The thickness of the insulating film 24 is 2 μm, and the thickness of the resin sheet 27 is 1
00 μm, the width of the electrode portions 21 and 22 is 30 μm, the distance between the electrode portions is 10 μm, and the size of the opening 25 is 60 μm × 60.
μm. In order to operate as an inkjet recording apparatus, a contact with a flexible terminal is further provided at the tip of the lead portion 23 opposite to the electrode portions 21 and 22 so that a driving voltage from the outside is loaded. In addition, a resin sheet 27 having nozzles 29 opened at substantially the same position is adhered on the opening 25 other than the insulating film 24 including the electrode portions 21 and 22, and the ink 28 boiled in contact with the electrode portions 21 and 22.
Is discharged from the nozzle 29. In this way, the pair of electrode portions 21 and 22 facing each other with a certain distance are arranged in the opening 25 not covered with the insulating film 24.
Further, the tips of the electrode portions 21 and 22 have appropriate curvatures. 30 is a power source, 31 is an energization switching means,
The electrodes 21 and 22 are energized via the wiring 32.

The voltage application method of this embodiment is shown in FIGS. The voltage applying method of FIGS. 3 to 6 shown in this embodiment is
Although the case where the present method is applied is shown based on the conventional voltage application method shown in FIG. 12, it may be based on the method shown in FIGS. 13 and 14.

FIG. 7 shows the ink ejection amount when the applied voltage value is changed, FIG. 8 shows the relationship between the deviation amount of the voltage change and the ink ejection amount, and FIG. 9 shows the voltage width change amount and the ink ejection amount. The relationship was shown.

As can be seen from FIGS. 3, 4, and 7, by decreasing the maximum voltage V _max , the time required until the start of boiling becomes longer, and therefore the ink ejection amount becomes larger. As can be seen from FIGS. 5 and 8, the pair of electrode portions 2
The voltage independently applied to each of 1 and 22 is the ground potential V _0.
In contrast, the ink 28 is heated by a means for temporally repeating positive / negative potential changes in substantially the same cycle, and the phase of the temporal repetition of the two voltage changes is temporally shifted, whereby the electrode portion 21, The potential difference across 22 is positive /
The ink ejection amount is changed by adjusting the ratio between the negative and negative / positive time lengths and the equipotential time length. As shown in FIG. 8, the time required until the start of boiling increases in proportion to the deviation amount a / b, and therefore the ink ejection amount increases. As is clear from FIG. 6 and FIG. 9, the voltage independently applied to each of the pair of electrode portions 21 and 22 is a temporal repetition of the positive / negative potential change with respect to the ground potential V ₀ in substantially the same cycle. The ink 28 is heated by the means and the positive and negative time widths of the two voltage changes are increased and decreased to increase or decrease the potential difference across the electrode portions 21 and 22. The time required until the start of boiling increases in proportion to the ratio c / b of the positive time length to the equipotential time length, and thus the ink ejection amount increases. In either case, the frequency of voltage change was 1 MHz in this case. The voltage waveform need not be a perfect square wave as shown. In the examples of FIGS. 5 and 6, the maximum voltage V _max is set to 10V.

[0018]

INDUSTRIAL APPLICABILITY The present invention applies a voltage between electrode parts in an ink jet recording apparatus in which a voltage is applied between a pair of electrode parts to boil the ink that directly or indirectly contacts the electrode parts and the ink is ejected from a nozzle. A method of changing the ink ejection amount by increasing or decreasing the magnitude of the voltage to be applied, or a voltage independently applied to each of the pair of electrode parts is positive / negative or positive / zero or negative / ground potential. By heating the ink by means of time repetition of substantially the same cycle of zero potential change, and shifting the time repetition of the two voltage changes temporally, the potential difference applied between the electrode parts is positive / negative and negative. / A method of changing the ink ejection amount by adjusting the ratio of the time length that is positive and the time length that is equipotential, or independent for each electrode part of a pair of electrode parts The ink is heated by a means in which the applied voltage is repeated positively / negatively or positively / negatively or positively / negatively or negatively / zeroly with respect to the earth potential in substantially the same cycle, and furthermore, the two voltage variations are repeated in time. By adjusting the ratio of the time length in which the potential difference applied between the electrode parts is positive / negative and negative / positive to the time length in which the potential is equal by increasing or decreasing the positive time width and the negative time width of Since the energy supplied between the electrode parts for ejecting ink can be increased or decreased, the ink ejection amount can be freely increased or decreased. Therefore, it is possible to control the variation of the ink dot amount and perform stable and uniform printing. Moreover, gradation recording can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view showing an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 3 is a waveform diagram showing a voltage application method for an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 4 is a waveform diagram showing a voltage application method for an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 5 is a waveform diagram showing a voltage application method for an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 6 is a waveform diagram showing a voltage application method for an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 7 is a graph showing changes in the ink ejection amount of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 8 is a graph showing changes in the ink ejection amount of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 9 is a graph showing changes in the ink ejection amount of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a conventional inkjet recording device.

FIG. 11 is a plan view showing a conventional inkjet recording apparatus.

FIG. 12 is a waveform diagram showing a voltage application method of a conventional inkjet recording apparatus.

FIG. 13 is a waveform diagram showing a voltage application method of a conventional inkjet recording apparatus.

FIG. 14 is a waveform diagram showing a voltage application method of a conventional inkjet recording apparatus.

[Explanation of symbols]

 21 Electrode Part 22 Electrode Part 23 Lead Part 24 Insulating Film 25 Opening 26 Substrate 27 Resin Sheet 28 Ink 29 Nozzle 30 Power Supply 31 Energization Switching Means 32 Wiring

Claims (3)

[Claims] 1. An ink ejection port comprising an ink flow path holding ink and an ink ejection port communicating with the ink flow channel, wherein a voltage is applied between a pair of electrode portions to supply ejection energy. An ink jet recording apparatus for ejecting ink from the ink jet recording apparatus, wherein the ink ejection amount is changed by increasing or decreasing a voltage applied between the electrode portions. 2. An ink ejection port comprising an ink flow path holding ink and an ink ejection port communicating with the ink flow channel, applying a voltage between a pair of electrode parts to supply ejection energy. An ink jet recording apparatus for ejecting ink from a pair of electrodes, wherein the voltage independently applied to each of the pair of electrode portions has substantially the same potential change of positive / negative or positive / zero or negative / zero with respect to the ground potential. By heating the ink by means of time repetition of the cycle and shifting the time repetition of the two voltage changes, the potential difference applied between the electrode parts is positive / negative and negative / positive An ink jet recording apparatus characterized in that an ink ejection amount is changed by adjusting a ratio with a time length which is an equipotential. 3. An ink ejection port comprising an ink flow path holding ink and an ink ejection port communicating with the ink flow channel, wherein a voltage is applied between a pair of electrode portions to supply ejection energy to the ink ejection port. An ink jet recording apparatus for ejecting ink from a pair of electrodes, wherein the voltage independently applied to each of the pair of electrode portions has substantially the same potential change of positive / negative or positive / zero or negative / zero with respect to the ground potential. By heating the ink by means of time repetition of the cycle, and increasing or decreasing the positive time width and the negative time width of the time repetition of the two voltage changes, the potential difference applied between the electrode parts becomes positive / negative. An ink jet recording apparatus, characterized in that an ink ejection amount is changed by adjusting a ratio of a negative / negative / positive time length and an equipotential time length.