JP5626027B2 - Liquid ejector - Google Patents

Description

The present invention relates to a liquid ejecting apparatus that ejects a liquid such as ink containing a volatile organic compound.

2. Description of the Related Art Printing apparatuses that print an image by ejecting ink onto a print medium are widely used. In this printing apparatus, a printing medium such as paper is conveyed by a conveying apparatus, and an image is printed by ejecting ink from the ejection head toward the printing medium.

In general, the ink contains a volatile organic compound such as an organic solvent. Therefore, when a large amount of ink is ejected onto the print medium, or when a large amount of ink is discharged during the flushing process or cleaning process, a large amount of volatile organic compounds are vaporized from the ink and air is discharged. May diffuse into the environment and contaminate the environment.

Therefore, conventionally, a technique for avoiding environmental pollution by collecting such vaporized volatile organic compounds with a filter has been proposed (Patent Document 1).

JP 2009-90480 A

However, in the proposed technique described above, there is a limit to the capacity of the volatile organic compound that can be collected by the filter, and thus there is a problem that the filter must be periodically replaced.

The present invention has been made to solve the above-described problems of the prior art,
The purpose is to provide a technology capable of suppressing environmental pollution caused by volatile organic compounds.

In order to solve at least a part of the problems described above, the liquid ejecting apparatus of the present invention employs the following configuration. That is,
A liquid ejecting apparatus that ejects a liquid containing a volatile organic compound from an ejection head,
A recovery unit that recovers the volatile organic compound vaporized from the liquid coming out of the ejection head together with air;
A combustion section comprising a platinum catalyst, and using the platinum catalyst, the recovered volatile organic compound reacts with oxygen in the air and burns;
An ammonia absorption refrigerator that uses ammonia as a refrigerant and water as an absorption liquid, and cools a heat generating part provided in the liquid ejecting apparatus,
The gist is to operate the ammonia absorption refrigerator by heating the aqueous ammonia solution with heat generated by combustion in the combustion section.

As described above, in the liquid ejecting apparatus according to the aspect of the invention, when the volatile organic compound is vaporized from the liquid discharged from the ejecting head, the volatile organic compound is collected in the collecting unit together with the air. The recovered volatile organic compound is supplied to a platinum catalyst provided in the combustion section, and reacts with oxygen in the air and burns. An ammonia absorption type refrigerator is an absorption type refrigerator that uses ammonia as a refrigerant and water as an absorption liquid, and cools a heat generating part (for example, a head drive circuit, a motor, a power supply, etc.) provided in the liquid ejecting apparatus. Used for. And the ammonia absorption type refrigerator is operated by heating the ammonia aqueous solution of the ammonia absorption type refrigerator using the heat generated by the combustion in the combustion section.

Therefore, according to the liquid ejecting apparatus of the present invention, the vaporized volatile organic compound is burned using the platinum catalyst and converted into a harmless gas, so that environmental pollution due to the volatile organic compound can be suppressed. it can. Further, the heat generating part such as the head drive circuit can be cooled by the ammonia absorption type refrigerator that operates using the heat generated by the combustion, that is, the waste heat from the combustion part. Therefore, there is no possibility that the head drive circuit, the motor, the power supply, etc. will malfunction due to heat generation, and it is not necessary to provide a large heat radiating fin, a cooling fan, etc. for cooling the head drive circuit. For this reason, it becomes possible to suppress the power consumption for driving the cooling fan and the generation of noise.

The liquid injection apparatus of the present invention described above may further include an auxiliary fuel supply unit that supplies auxiliary fuel from the auxiliary fuel tank to the combustion unit.

In this way, even if it is difficult to generate sufficient reaction heat with the platinum catalyst because the temperature of the air is extremely low or the concentration of the volatile organic compound is low in the combustion section, the auxiliary fuel By supplying the auxiliary fuel to the combustion section at the supply section, it is possible to generate sufficient reaction heat with the platinum catalyst and maintain the combustion reaction. For this reason, even when the temperature of the air is extremely low or the concentration of the volatile organic compound is low, it is possible to cool the heat generating portion such as the head drive circuit.

Further, in the liquid ejecting apparatus of the present invention described above, a heater may be provided in a combustion unit that burns a volatile organic compound.

In this way, because the temperature of the air is extremely low or the concentration of the volatile organic compound is low, reaction heat sufficient to maintain the temperature of the platinum catalyst cannot be obtained, and as a result, combustion is maintained. Even if this is difficult, the temperature of the platinum catalyst can be maintained by heating with a heater. For this reason, even when the temperature of the air is extremely low or the concentration of the volatile organic compound is low, it is possible to cool the heat generating portion such as the head drive circuit using the ammonia absorption refrigerator.

Furthermore, in the liquid ejecting apparatus of the present invention described above, the ammonia absorption type refrigerator may include an aqueous ammonia solution tank, a separator, a condenser, a vaporizer, and an absorber.
Among these, the ammonia aqueous solution tank is arrange | positioned so that a combustion part may be contacted, and the heat which generate | occur | produced by combustion is transmitted from a combustion part. And the stored aqueous ammonia solution
By being heated by the heat, a mixed gas of ammonia and water vapor is generated. The mixed gas generated in the ammonia aqueous solution tank is sent to the separator to be separated into ammonia gas and water. The ammonia gas therein is cooled by a condenser, aggregated into liquid ammonia, and sent to a vaporizer. In the vaporizer, the condensed liquid ammonia is vaporized under reduced pressure. At this time, ammonia takes heat of vaporization, and the heat of vaporization such as the head drive circuit is cooled by the heat of vaporization. The vaporizer may be disposed in contact with the head drive circuit or the like, or the vaporizer and the head drive circuit may be connected with a member having good heat conductivity. The ammonia gas vaporized by the vaporizer is sent to the absorber. In the absorber, an aqueous ammonia solution is generated by absorbing ammonia gas in the water separated by the separator. The produced aqueous ammonia solution is returned to the aqueous ammonia solution tank and reused.

In this way, it is possible to efficiently cool the heat generating part such as the head drive circuit by operating the ammonia absorption type refrigerator using the waste heat from the combustion part.

It is sectional drawing which showed typically the principal part in the inkjet printer 100 as an Example of this invention.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Example configuration:
B. Example operation:
C. Modified example:

A. Example configuration:
FIG. 1 is a cross-sectional view schematically showing main parts of an ink jet printer 100 as an embodiment of the present invention. The inkjet printer 100 is a large business printer.

As shown in FIG. 1, an ejection head 102 for ejecting ink downward is provided at the center of the inkjet printer 100. Below the ejection head 102, a paper conveyance device 104 for conveying the paper 110, which is a printing medium, is disposed. The paper transport device 104 includes two rotating rollers 106a and 106b and a transport belt 108 that is spanned between the two rollers 106a and 106b. A paper feed port 1 for feeding paper 110 is provided in the casing of the inkjet printer 100.
12 and a paper discharge port 114 for discharging the paper 110 to the outside. Also,
A head driving circuit 158 is connected to the ejection head 102 via a signal line 160. The head drive circuit 158 is housed in the heat insulation case 162.

A gas recovery pump 116 is provided in the vicinity of the ejection head 102. An intake pipe 118 extending downward is connected to the gas recovery pump 116. Ejection head 102
Ejects ink downward, but the other end of the intake pipe 118 opens into a space on the ink ejection side. Further, the gas recovery pump 116 has a pipe 120 extending to the right.
The other end of the pipe 122 is connected to the combustion unit 122. The combustion unit 122 includes a platinum catalyst (not shown) therein. The combustion section 122 has a pipe 1
An auxiliary fuel tank 166 is connected via 68. In addition, an exhaust duct extending to the outside of the inkjet printer 100 is connected to the combustion unit 122, but is omitted in FIG.

Above the combustion unit 122, the head drive circuit 158 is utilized using waste heat from the combustion unit 122.
An absorption refrigerator 164 is provided for cooling the air. The absorption refrigerator 164 is an ammonia absorption refrigerator that uses ammonia as a refrigerant and water as an absorption liquid. Absorption type refrigerator 1
64 is mainly an aqueous ammonia tank 124 that functions as a generator, a separator 128 that functions as a separator, a condenser 134 that functions as a condenser,
A vaporizer 138 that functions as an evaporator and an absorber 14 that functions as an absorber.
2 and a liquid receiving tank 144.

Among these, the ammonia aqueous solution tank 124 is disposed on the combustion unit 122 so as to be in contact with the combustion unit 122. Inside the aqueous ammonia solution tank 124, an aqueous ammonia solution 150 in which ammonia is absorbed by water is stored. This aqueous ammonia tank 1
A pipe 126 is connected to 24, and the other end of the pipe 126 is connected to a separator 128. A pipe 130 and a pipe 132 are connected to the separator 128. The other end of the pipe 130 is connected to a condenser 134 having a cooling fin 134a around it. Condenser 13
4, a pipe 136 is connected, and the other end of the pipe 136 is a U-shaped vaporizer 138.
It is connected to the. A pipe 140 is connected to the vaporizer 138, and the other end of the pipe 140 is connected to the liquid receiving tank 144. On the other hand, the other end of the pipe 132 is connected to an absorber 142 having a cooling fin 142a around it. The absorber 142 further includes a pipe 146.
Is connected to the liquid receiving tank 144. The liquid receiving tank 144 is connected to the ammonia aqueous solution tank 124 via a pipe 148.

In this embodiment, the gas recovery pump 116, the intake pipe 118, and the pipe 120 correspond to the “recovery unit” in the claims. The auxiliary fuel tank 166 and the pipe 168 correspond to an “auxiliary fuel supply unit” in the claims.

B. Example operation:
At the time of printing, the paper 110 that is a printing medium is fed from the paper feed port 112 and then placed on the transport belt 108 of the paper transport device 104 and is transported in the direction of the arrow as the transport belt 108 moves. . When the paper 110 passes below the ejection head 102, the ejection head 102 is driven by the head drive circuit 158 so that ink is ejected from the ejection head 102 toward the paper 110, thereby The image is printed on. The printed paper 110 is further transported by the transport belt 108 and is then discharged to the outside from the paper discharge port 114.

In general, the ink contains a volatile organic compound such as an organic solvent. Then, when the ink is ejected from the ejection head 102 or after adhering to the paper 110, the volatile organic compound is vaporized from the ink, diffuses into the air, and becomes united with the air. Accordingly, a large amount of volatile organic compound is contained in the air in the ink ejection space below the ejection head 102. Therefore, the environment may be polluted with these volatile organic compounds as they are. Note that this can occur not only during printing, but also during flushing processing and cleaning processing.

Therefore, in this embodiment, during printing or the like, the gas recovery pump 116 is driven to recover the vaporized volatile organic compound together with air from the opening of the intake pipe 118. The gas recovery pump 116 sends the recovered volatile organic compound and air to the combustion unit 122 via the pipe 120. As described above, since the combustion unit 122 includes a platinum catalyst, the volatile organic compound and air are exposed to the platinum catalyst. As a result, in the platinum catalyst portion, the volatile organic compound reacts with oxygen in the air and burns at a low temperature of about 200 ° C to 400 ° C. Carbon dioxide, water vapor and the like generated as a result of combustion are discharged to the outside of the ink jet printer 100 through the exhaust duct.

When the temperature of the platinum catalyst is 200 ° C. or lower, it becomes difficult to maintain combustion. Therefore, when the temperature of the air supplied to the platinum catalyst is extremely low, it is difficult to maintain the temperature of the platinum catalyst, or because the concentration of volatile organic compounds is low, When it is difficult to maintain the temperature of the catalyst, it is difficult to maintain the combustion reaction with the platinum catalyst. However, in normal cases, the temperature of the platinum catalyst is maintained at 200 ° C. or higher by the combustion heat generated by the platinum catalyst.

On the other hand, an ammonia aqueous solution tank 124 is disposed on the combustion unit 122 so as to come into contact therewith. Therefore, when a combustion reaction occurs in the combustion unit 122, the heat generated by the combustion is transferred as waste heat to the ammonia aqueous solution tank 124 and heats the ammonia aqueous solution 150 in the ammonia aqueous solution tank 124. Then, ammonia and water are vaporized in the ammonia aqueous solution tank 124 to generate a mixed gas of ammonia and water vapor, and the mixed gas is sent to the separator 128 via the pipe 126.

Since ammonia has a lower boiling point than water, when the temperature of the mixed gas decreases in the separator 128, the ammonia remains as a gas (gas), the water vapor returns to water (liquid), and ammonia and water are separated. . The separated water 154 travels through the pipe 132 and is sent to the absorber 142 at a lower position. On the other hand, the ammonia gas 152 rises upward and is sent to the condenser 134 via the pipe 130. In the condenser 134, the ammonia gas 152 is air-cooled using the cooling fins 134a and is condensed into liquid ammonia. Its liquid ammonia 15
6 is sent to the vaporizer 138 via the pipe 136. The vaporizer 138 is disposed in the vicinity of the head drive circuit 158 in the heat insulating case 162 as shown in FIG. Vaporizer 13
In 8, the liquid ammonia 156 having a high concentration is depressurized and vaporized. At that time, the surrounding heat is taken away as heat of vaporization, so that cooling occurs. Thereby, the head drive circuit 158 accommodated in the heat insulation case 162 is cooled.

Thereafter, the vaporized ammonia gas 152 is sent to the liquid receiving tank 144 and further to the absorber 142 via the pipe 140. In the absorber 142, the ammonia gas 152 is supplied to the pipe 13.
2 is absorbed by the water 154 transmitted through the water 2, and an aqueous ammonia solution 150 is generated. The aqueous ammonia solution 150 is collected in the liquid receiving tank 144 and then returned to the aqueous ammonia solution tank 124 via the pipe 148 for reuse.

As described above, when the temperature of the air supplied to the platinum catalyst is extremely low, it is difficult to maintain the temperature of the platinum catalyst, or the concentration of the volatile organic compound is low. When it is difficult to maintain the temperature of the platinum catalyst with the obtained heat, it is difficult to maintain the combustion reaction with the platinum catalyst. Therefore, in this embodiment, in such a case, auxiliary fuel is supplied from the auxiliary fuel tank 166 to the combustion unit 122 via the pipe 168. As a result, in the combustion unit 122, the combustion reaction using the platinum catalyst is promoted by the supplied auxiliary fuel, so that the temperature of the platinum catalyst rises and combustion can be maintained. Thereby, even when the temperature of the air is extremely low or the concentration of the volatile organic compound is low, the combustion reaction with the platinum catalyst can be maintained.

As the auxiliary fuel, it is preferable to use a combustible gas such as hydrogen, methane, alcohol, or benzene. However, sulfur compounds, phosphine, halogen compound ions, amines, carbon monoxide, etc. cannot be used as auxiliary fuel. This is because these substances are preferentially adsorbed to the active site (the place where the reaction proceeds) in the platinum catalyst, preferentially adsorbing over the substrate, thus greatly reducing (poisoning) the catalytic activity of platinum. is there.

As described above, according to the present embodiment, the volatile organic compound diffused in the air is recovered, burned using a platinum catalyst, and converted into a harmless gas such as carbon dioxide or water vapor. , Environmental pollution by volatile organic compounds can be suppressed. In addition, by using a platinum catalyst, it is not necessary to replace the catalyst periodically, so the maintenance load can be reduced. Moreover, since it is made to burn using a platinum catalyst, 200 degreeC-400, without giving out a flame.
Since combustion at a low temperature of about 0 ° C. is possible, safety can be improved.

Here, recent ink jet printers are required to improve printing speed and increase resolution, and accordingly, the amount of heat generated in the head drive circuit tends to increase. Furthermore, in the case of a large-sized printer for business use, the head drive circuit has become larger due to demands for larger size and higher speed. Therefore, the amount of heat generated from the head drive circuit is also increasing. Also, the amount of heat generation tends to increase for motors and power supplies used as actuators. Conventionally, the head drive circuit and the like have been cooled using a cooling device such as a cooling fan in response to such an increase in heat generation. However, when the heat generation amount increases, a large-scale cooling device is required, which may increase power consumption and noise.

On the other hand, in the present embodiment, the head drive circuit 158 and the like are cooled by the absorption chiller 164 using the heat generated by the combustion, that is, the waste heat from the combustion unit 122, so that the cooling fan As compared with the conventional case using the above, power consumption can be suppressed and noise can also be reduced.

C. Modified example:
Although the embodiment has been described above, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the scope of the invention.

In the above-described embodiment, when the temperature of the air is extremely low or the concentration of the volatile organic compound is low, auxiliary fuel is used to maintain the combustion reaction with the platinum catalyst. The present invention is not limited to this. For example, a heater may be provided inside the combustion section 122 and the platinum catalyst may be heated by starting the heater. Moreover, you may make it utilize both an auxiliary fuel and a heater.

In the above-described embodiments, the cooling target is the head drive circuit. However, the present invention is not limited to this, and other drive circuits, power supply circuits, motors, and the like can be cooled. Good.

100 ... Inkjet printer, 102 ... Ejection head,
104: Paper conveying device 106a, 106b: Roller 108: Conveying belt,
110: paper, 112 ... paper feed port, 114 ... paper discharge port,
116 ... Gas recovery pump, 118 ... Intake pipe, 120 ... Piping,
122 ... Combustion section, 122 ... Piping, 124 ... Ammonia aqueous solution tank,
126 ... Piping, 128 ... Separator, 130,132 ... Piping,
134 ... condenser, 134a ... cooling fins, 136 ... piping,
138 ... vaporizer, 140 ... piping, 142 ... absorber,
142a ... cooling fins, 144 ... liquid receiving tank, 146, 148 ... piping,
150 ... Ammonia aqueous solution, 152 ... Ammonia gas, 154 ... Water,
156 ... Liquid ammonia, 158 ... Head drive circuit, 160 ... Signal line,
162 ... heat insulation case, 164 ... absorption refrigerator, 166 ... auxiliary fuel tank,
168 ... Piping

Claims (4)

A liquid ejecting apparatus that ejects a liquid containing a volatile organic compound from an ejection head,
A recovery unit that recovers the volatile organic compound vaporized from the liquid coming out of the ejection head together with air;
A combustion section comprising a platinum catalyst, and using the platinum catalyst, the recovered volatile organic compound reacts with oxygen in the air and burns;
An ammonia absorption refrigerator that uses ammonia as a refrigerant and water as an absorption liquid, and cools a heat generating part provided in the liquid ejecting apparatus,
A liquid ejecting apparatus that operates the ammonia absorption refrigerator by heating the aqueous ammonia solution with heat generated by combustion in the combustion section. The liquid ejecting apparatus according to claim 1,
A liquid injection apparatus including an auxiliary fuel supply unit that supplies auxiliary fuel from an auxiliary fuel tank to the combustion unit.   The liquid ejecting apparatus according to claim 1, wherein the combustion unit includes a heater. The liquid ejecting apparatus according to any one of claims 1 to 3,
The ammonia absorption refrigerator is
The ammonia aqueous solution is stored and disposed so as to be in contact with the combustion part, and the ammonia aqueous solution to be stored is heated by heat generated by combustion in the combustion part, thereby producing a mixed gas of ammonia and water vapor. A generated ammonia aqueous solution tank;
A separator for separating the mixed gas into ammonia gas and water;
A condenser that cools the ammonia gas and aggregates into liquid ammonia;
A vaporizer that is disposed in the vicinity of the head drive circuit, vaporizes the liquid ammonia into ammonia gas, and cools the heat generating portion of the liquid ejecting apparatus with the heat of vaporization;
A liquid ejecting apparatus comprising: an absorber that absorbs the vaporized ammonia gas in water separated by the separator and generates the aqueous ammonia solution.

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