JPH09141893A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wear of an electrode and to stabilize an ink emitting start time to enhance reliability by forming a carriage to which an ink tank is attached into a container shape made of a synthetic resin of which the specific surface is opened from an ink jet head. SOLUTION: A carriage 4 is a cartridge formed by fixing an ink jet head 1 and an ink tank 2 by an adhesive and a flexible substrate 5 is fixed from the directions of an 1a surface and a 1b surface and a 1c surface and a 1d surface in a lateral direction and a 1e surface and 1f surface in an up-and-down direction are formed from a synthetic resin so as to cover a periphery excepting the wiring passing hole of the flexible substrate 5. Therefore, by forming the carriage from a synthetic resin, the charge of the carriage is eliminated and the redox reaction caused by the difference between the potential of ink through the ink of the ink tank and the potential of an electrode and the wear of the electrode are not generated and reliability can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer that ejects ink to print on recording paper or the like.

[0002]

2. Description of the Related Art In recent years, inkjet printers have come to be widely used as output printers for home and office computers because of their quietness during recording, high-speed recording capability, and easy colorization. Such ink-jet printers perform printing by making ink into small droplets and flying and attaching them to recording paper, and are broadly classified into a continuous system and an on-demand system according to a method of generating droplets and a method of controlling a flying direction. You.

The continuous system is a system disclosed in, for example, US Pat. No. 30,604,29, in which ink droplets are electrostatically attracted and the generated droplets are voltage-controlled according to a recording signal. In addition, small droplets are selectively deposited on the recording paper for recording, and high voltage is required to generate small droplets, making it difficult to use multiple nozzles, which makes it unsuitable for high-speed recording. . The on-demand system is a system disclosed in, for example, U.S. Pat. No. 3,474,120, in which an electric recording signal is added to a piezo vibrating element attached to a recording head having a nozzle hole for ejecting a small droplet. Then, the electric recording signal is converted into mechanical vibration of the piezo vibrating element, and small ink droplets are ejected from the nozzle holes according to the mechanical vibration and adhered to the recording paper to perform recording. Since recording is performed by ejecting from the nozzle hole, it is not necessary to collect the droplets that were not required to record the image among the droplets that are ejected and ejected as in the continuous method, so a simple configuration is possible. Is.
However, since it is difficult to process the recording head and it is extremely difficult to miniaturize the piezo-vibration element, it is difficult to make it into a multi-nozzle. Also, since the mechanical energy of mechanical vibration of the piezo-element causes droplets to fly, high-speed recording is possible. It has drawbacks such as being unsuitable. Also, Japanese Patent Publication Sho 61-5991
No. 1, Japanese Patent Publication No. 62-11035, and Japanese Patent Publication No. 6
Japanese Patent Laid-Open No. 1-59914 discloses a recording method of a system in which boiling of ink is caused by a heating resistor to cause droplets to fly.

As another example of the on-demand system, the system disclosed in US Pat. No. 3,179,042 discloses that thermal energy is used instead of mechanical vibration energy by means such as a piezoelectric vibration element. Has been done. Compared with the method of using mechanical vibration energy, the method of using thermal energy is characterized by high energy conversion efficiency and easy multi-nozzle formation.

A conventional ink jet printer will be described below with reference to the drawings. FIG. 3 is a perspective view of an essential part of a conventional inkjet printer, and FIG. 4 is a perspective view of an essential part of a carriage part of the conventional inkjet printer. In FIG. 3, a cartridge 53 including an electrically heating type inkjet head 51 is mounted on a carriage 54. The carriage 54 contacts the rail 58, follows the belt 60 that is rotationally driven by the motor 59, and guides the guide shaft 6.
Move up 1. The inkjet head 51, which is a part of the carriage 54, and the print control circuit 56 are connected by a flexible substrate 55, which is an electric wiring, and a voltage is applied to the inkjet head 51 from the print control circuit 56 while the carriage 54 is moving. When applied, the recording paper 57
Print on. In FIG. 4, an inkjet head 51
Is fixed to the ink tank 52 made of ABS resin with an adhesive to form a cartridge 53. The carriage 54 fixes the cartridge 53 and the flexible substrate 55 so as to be in close contact with each other from the directions 54a and 54b, and contacts the ink tank 52 so as not to be laterally displaced from the directions 54c and 54d. The lower portion receives the 54f surface and is arranged so as not to be displaced in the vertical direction, and the upper 54e surface has a structure in which the cartridge 53 can be detachably taken out.

The operation of the ink jet printer configured as described above will be described below with reference to the drawings. FIG. 5 is a sectional view of a main part of a carriage and a cartridge in a conventional inkjet printer.
FIG. 6A is a schematic diagram showing a state in which bubbles are generated in a conventional inkjet printer, and FIG.
FIG. 6 is a schematic diagram showing an ink ejection state in a conventional inkjet printer, and FIG. 6C is a schematic diagram showing an ink inflow state in a conventional inkjet printer. First, as shown in FIG. 6A, the print control circuit 5
From 6, the applied voltage, frequency, and time for heating ink are 25
An alternating current voltage of V, 3 MHz, 40 μs, and a driving frequency of 5 kHz, which is the frequency from the driving to the next driving, is applied, and a current is caused to flow through the ink through the electrodes for electric heating 62a and 62b. Electricity is supplied to the ink between the ink and the electrodes for electric heating 62a and 62b. Then, the Joule heat of the ink itself causes the ink to heat and boil, and a bubble 63 is generated between the electrodes for electric heating 62a and 62b. Next, as shown in FIG. 6B, as the bubble 63 expands, an ink droplet 64 is ejected and fly to the recording paper 57. Further, as shown in FIG. 6C, the ink flows from the ink inlet (not shown) through the ink flow path 65 to the ink chamber 66.
The inside is filled and the operation of ejecting ink is completed.

[0007]

However, in the above conventional structure, electric noise and leakage current from the contact portion between the flexible substrate and the ink jet head generated during energization cause electric charges to be accumulated in the carriage, and outside the energization, Since the charge of the carriage raises the potential of the ink in the ink tank, a stable AC voltage cannot be supplied between the electrodes for energization heating during energization, and ink drops after the AC voltage is applied to the electrodes for energization heating. There is a problem that the time until ink is ejected (hereinafter referred to as ink ejection start time) becomes long, and as a result, a phenomenon of ejection failure easily occurs and printing is not performed. Further, outside the energization, the accumulated charge is applied to the energization heating electrode through the ink in the ink tank and a potential difference is generated between the electrode and the ink, so that an oxidation-reduction reaction occurs in the electrode, resulting in wear of the electrode. The distance between the electrodes becomes long, and the resistance of the ink between the electrodes changes even if an applied voltage of 25 V is applied to the electrodes for energization heating, so a constant current does not flow between the electrodes and the ink ejection start time is stable. Therefore, there is a problem in that the reliability of the inkjet printer is impaired.

The present invention solves the above-mentioned problems of the prior art by preventing leakage current in the carriage during energization, eliminating charge, and applying a stable AC voltage from the print control circuit when forming bubbles in the ink. , Outside the energization,
Provides a highly reliable inkjet printer that prevents the potential difference between the ink potential and the electrode for electric heating through the ink, suppresses the redox reaction of the electrode, prevents electrode wear, stabilizes the ink discharge start time The purpose is to do.

[0009]

In order to solve this problem, in the ink jet printer of the present invention, the carriage for fixing the cartridge and the flexible substrate has a carriage between the ejection portion of the ink jet head and the wiring portion of the flexible substrate. It has a container-like shape and is made of plastic having a volume resistance of the carriage material of 10 ⁶ Ωm or more and a relative dielectric constant of 5 or less. As its material, phenol resin, polyethylene terephthalate,
Polyester resin, alkyd resin, epoxy resin, polyamide resin, polyacetal resin, polycarbonate resin, silicone resin, fluororesin, Teflon, polyarylate, polypropylene, polyethylene, ABS resin,
It has a structure made of celluloid.

With this structure, the cartridge including the ink jet head and the ink tank and the flexible substrate are covered, and by using the plastic material, the contact between the flexible substrate and the ink jet head, which is generated during energization, Since electric noise and wetting current can be suppressed, charge accumulation in the carriage can be prevented. In addition to energization, the electric charge from the charged carriage passes through the ink in the ink tank regardless of the electrode for energization and heating, so that the potential difference can be eliminated, the redox reaction is eliminated, and electrode wear can be prevented. Furthermore, since the ac applied voltage for flowing the current for forming bubbles necessary for ink droplet ejection can be stably supplied due to the disappearance of charge accumulation, the ink ejection start time can be stabilized. The reliability of the inkjet printer can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet printer according to claim 1 of the present invention is an ink flow path, an ink inflow port formed at an end of the ink flow path, and an ink flow path opposite to the ink flow in port side. Of the nozzle head formed on the upper surface of the end portion on the side of the ink jet head, and an ink jet head including two opposing heating electrodes arranged on the lower surface of the end portion where the nozzle hole of the ink flow path is formed; An ink jet printer including an ink tank for supplying the ink, a flexible substrate for wiring for driving the ink jet head, and a carriage for mounting the ink jet head, the ink tank, and the flexible substrate, wherein the carriage ejects ink from the ink jet head. Formed in the shape of a synthetic resin container with an open surface excluding the wiring part of the flexible board It has formed.

With this structure, electrical noise and leakage current are suppressed from the flexible substrate and the ink jet head contact portion which are generated during energization, and it is possible to prevent charge accumulation in the carriage. As a result, the charge from the charged carriage is not applied to the electrodes for energization heating through the ink in the ink tank outside the energization, and the potential difference is not generated,
It is possible to prevent the redox reaction from occurring and prevent electrode wear.

An ink jet printer according to a second aspect of the present invention has the structure according to the first aspect, in which the volume resistivity of the synthetic resin is 10 ⁶ Ωm or more. With this configuration, it is possible to prevent charge accumulation in the carriage, prevent electrode wear, and stabilize the ink ejection start time.

An ink jet printer according to claim 3 of the present invention is the inkjet printer according to claim 1 or 2, wherein:
The synthetic resin has a relative dielectric constant of 5 or less.
With this configuration, it is possible to suppress the charge storage amount of the carriage to a low level.

An ink jet printer according to a fourth aspect of the present invention is the ink jet printer according to any one of the first to third aspects,
Synthetic resin is phenol resin, polyethylene terephthalate, polyester resin, alkyd resin, epoxy resin,
Polyamide resin, polyacetal resin, polycarbonate resin, silicone resin, fluororesin, Teflon, polyarylate, polypropylene, polyethylene, ABS resin, celluloid or a composite product thereof or a filler such as carbon fiber, glass fiber or metal fiber The resin composition has any one of the resin compositions. With this configuration, the ink ejection start time at the time of 100 million ejections can be set to 50% or less compared to the conventional metal carriage, and extremely high printing characteristics can be obtained. Further, the distance between the electrodes can be prevented from being worn as compared with the conventional one.

An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a perspective view of an essential part of an inkjet printer carriage according to an embodiment of the present invention, and FIG. 2 is a sectional view of an essential part of an inkjet printer carriage according to an embodiment of the present invention. is there. 1 is an inkjet head of an electric heating type, 4 is a volume resistivity of 10 ⁶ Ω
A carriage 3 made of a synthetic resin having a relative permittivity of 5 or less and a relative dielectric constant of 5 or less. Inside the carriage 4, a cartridge 3 in which an inkjet head 1 and an ink tank 2 are integrated.
Contains. 5 is a flexible substrate which is an electric wiring for passing an electric current, 6 is a print control circuit, 7 is an ink chamber, 8a, 8
Reference numeral b is an electrode, 9 is a bubble, 10 is an ink drop, 11 is an ink hole, and 12 is a recording paper.

The carriage 4 fixes the cartridge 3 to which the ink jet head 1 and the ink tank 2 are fixed with an adhesive and the flexible substrate 5 from the directions of 1a surface and 1b surface, and the horizontal direction is the 1c surface, 1d surface, and the vertical direction. 1e surface, 1f
The surface is formed of synthetic resin having a thickness of 2 mm to 10 mm so as to cover the periphery of the flexible substrate 5 except for the holes through which the wiring passes.

The operation of the ink jet printer configured as described above will be described. Print control circuit 6
AC voltage is applied between the electrodes 8a and 8b of the ink chamber 7 of the inkjet head 1 through the flexible substrate 5 to energize in the ink, and the ink is heated and boiled by the Joule heat of the ink itself, so that the electrode 8a , 8b, an ink droplet 10 is ejected from the ink hole 11 to fly to the recording paper 12 for printing.

[0019]

【Example】

(Example 1) As a synthetic resin, the volume resistivity is 10 ⁶ Ω.
Carriage 4 was prepared using a carbon-containing polycarbonate having a m of m and a relative dielectric constant of 2.85 with an interelectrode distance of 4 μm and an electrode width of 30 μm. Next, using this carriage 4, the ink electrode and the ink ejection start time were measured. The ink potential was measured by immersing the platinum electrode in the ink in the ink tank 2 and measuring the potential measured by the platinum electrode immediately after the completion of energization. The ink ejection start time is 10 million times to 1 which is the number of ejections of ink used for printing.
The ink ejection start time was measured at 100 million times. The results are shown in (Table 1).

Example 2 A carriage 4 was manufactured in the same manner as in Example 1 except that a glass fiber-containing polycarbonate resin having a volume resistivity of 10 ¹⁴ Ωm and a relative dielectric constant of 2.85 was used as the material of the carriage 4. The ink ejection start time was measured. The results are shown in (Table 1).

Example 3 A carriage was prepared in the same manner as in Example 1 except that Teflon having a volume resistivity of 2 × 10 ⁴ Ωm and a relative dielectric constant of 2 was used as the material of the carriage 4, and the ink ejection start time was set. Was measured. The results are shown in (Table 1).

Comparative Example 1 As a comparative example, a conventional steel (S
A carriage was prepared in the same manner as in Example 1 except that (US) was used, and the ink ejection start time was measured. The results are shown in (Table 1).

[0023]

[Table 1]

As is clear from this (Table 1), the ink jet printer according to Example 1 has an ink potential of 3.65 in Comparative Example 1 which is a conventional ink jet printer.
In comparison with V, the ink potential outside the energization is -0.35V so that the ink is not charged, and at the number of ejections of the ink used for printing is 10 million to 100 million times,
18 μs when the ink ejection start time is 10 million times,
20.3 μs in 100 million times, 20.6 μs in 10 million times in Comparative Example 1 and 43.4 μs in 100 million times
In comparison with Comparative Example 1, the ink ejection start time is more stable, and the distance between the electrodes 8a and 8b, which is a wear of the electrodes 8a and 8b, is 5.06 μm in the present Example 1, and 5.
It can be seen that the wear of the electrodes 8a and 8b is reduced to 5 μm. This is because the ink discharge start time is stable, so that the ink potential approaches 0 V, the AC voltage applied during driving is directly applied to the electrodes 8a and 8b, and the ink potential and the electrode due to charging are changed. The potential difference between 8a and 8b is eliminated, the redox reaction is eliminated, and the electrodes 8a and 8b
By preventing wear, the AC voltage is kept constant by the electrodes 8a, 8
It was found that an excellent effect of stabilizing the ink ejection start time can be obtained by applying the voltage to b.

Further, the ink jet printer according to the second embodiment has an ink potential of -0.25 V, which is less likely to be charged than that of the conventional example, and the ink is ejected at a printing frequency of 10 million to 100 million times. It was found that the discharge start time was 20 μs at 10 million times and 22.5 μs at 100 million times, which was more stable than the ink jet printer of the related art, and the same effect as described above was obtained.

In the ink jet printer according to the third embodiment, the ink potential is 1 V, which is less likely to be charged than in the conventional example, and the number of ejections used for printing is 1
In 10 to 100 million times, the ink ejection start time is 27 μs at 10 million times and 28.
It was found that the ink discharge start time was 9 μs, which was more stable than that of the conventional inkjet printer, and the same effect as described above was obtained.

As described above, according to this embodiment, the shape of the carriage 4 is changed, and the volume resistivity of the material is 1
0 ⁶ [Omega] m or more, since the specific dielectric constant by providing the 5 following carbon added polycarbonate, electrodes 8a stable AC voltage while power, supplied to 8b, there is no charge on the carriage 4 is out of conduction, the ink tank 2 does not cause an oxidation-reduction reaction caused by the potential difference between the ink potential and the electrodes 8a and 8b through the second ink, eliminates the wear of the electrodes 8a and 8b due to the charge, and eliminates the charge, so that the amplitude required for ejecting the ink droplet 10 is reduced. Since the AC applied voltage of 25 V can be stably supplied, the ink ejection start time can be stabilized and the reliability of the inkjet printer can be improved.

As the material of the carriage 4, carbon-added polycarbonate, glass fiber-added polycarbonate, and Teflon are used, but other materials such as plastics having a low volume efficiency of 10 ⁶ Ωm or more are preferable. As the volume low efficiency becomes less than 10 ⁶ Ωm, the carriage 4 tends to be easily charged, and if the plastic is 10 ⁶ Ωm or more, it tends to be difficult to charge.
It is preferable that the plastic is 0 ⁶ Ωm or more.

The material of the carriage 4 has a relative dielectric constant of 5
The following plastics are preferred. As the relative permittivity of the carriage 4 exceeds 5, the carriage 4 tends to be charged, which is not preferable.

In this example, carbon-added polycarbonate and Teflon were used, but the volume resistivity was 1
It goes without saying that a highly reliable ink jet printer can be realized even if a plastic having a relative dielectric constant of 0 ⁶ Ωm or more and 5 or less is used. Therefore, the plastic used in this example does not limit the present invention.

[0031]

As described above, according to the present invention, the volume resistivity of the surface of the carriage excluding the ejection portion of the ink jet head and the wiring portion of the flexible substrate is 10 ⁶ Ωm or more,
By using a synthetic resin with a relative permittivity of 5 or less, the charge of the carriage is eliminated, and the redox reaction caused by the potential difference between the ink potential and the electrode through the ink in the ink tank does not occur, and the electrode wear due to the charge is eliminated. Further, since the AC applied voltage having the amplitude of 25V necessary for ejecting the ink droplets can be stably supplied due to the disappearance of the charge, it is possible to realize a highly reliable apparatus for the inkjet printer, which stabilizes the boiling start time. is there.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a carriage of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of a carriage of an inkjet printer according to an embodiment of the present invention.

FIG. 3 is a perspective view of a main part of a conventional inkjet printer.

FIG. 4 is a perspective view of a main part of a conventional inkjet printer carriage.

FIG. 5 is a cross-sectional view of essential parts of a carriage and a cartridge in a conventional inkjet printer.

FIG. 6A is a schematic diagram showing a state in which bubbles are generated in a conventional inkjet printer. FIG. 6B is a schematic diagram showing an ink ejection state in the conventional inkjet printer. FIG. 6C is a diagram showing an ink inflow state in the conventional inkjet printer. Pattern diagram

[Explanation of symbols]

 1 Inkjet head 2 Ink tank 3 Cartridge 4 Carriage 5 Flexible substrate 6 Printing control circuit 7 Ink chamber 8a, 8b Electrode 9 Bubble 10 Ink droplet 11 Ink hole 12 Recording paper 51 Inkjet head 52 Ink tank 53 Cartridge 54 Carriage 55 Flexible substrate 56 Printing Control circuit 57 Recording paper 58 Rail 59 Motor 60 Belt 61 Guide shafts 62a, 62b Electric heating electrode 63 Bubble 64 Ink droplet 65 Ink flow path 66 Ink chamber

Claims (4)

[Claims] 1. An ink flow path, an ink inflow port formed at an end of the ink flow path, and a nozzle hole formed at an upper surface of an end of the ink flow path opposite to the ink inflow side. ,
An inkjet head including two opposing heating electrodes disposed on the lower surface of the end of the ink flow path where the nozzle hole is formed, an ink tank for supplying ink to the inkjet head, and the inkjet head An inkjet printer comprising: a flexible substrate of wiring for driving the inkjet head; the ink jet head; the ink tank; and a carriage for mounting the flexible substrate, wherein the carriage ejects the ink from the inkjet head and the flexible substrate. An ink jet printer characterized by being formed in a container shape made of a synthetic resin, the surface of which is open except the wiring part. 2. The ink jet printer according to claim 1, wherein the volume resistivity of the synthetic resin is 10 ⁶ Ωm or more. 3. The inkjet printer according to claim 1, wherein the synthetic resin has a relative dielectric constant of 5 or less. 4. The synthetic resin is a phenol resin, polyethylene terephthalate, polyester resin, alkyd resin, epoxy resin, polyamide resin, polyacetal resin, polycarbonate resin, silicone resin, fluororesin, Teflon, polyarylate, polypropylene, polyethylene, 4. An ABS resin, a celluloid, or a composite product thereof, or a resin composition of any one of these and a filler such as carbon fiber, glass fiber, metal fiber, etc. 1. The inkjet printer according to 1.