JP4671827B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an inkjet recording apparatus that performs recording by ejecting ink onto a recording medium such as paper, and more particularly to an inkjet recording apparatus that uses high-viscosity ink as ink.

  The configuration of a conventional ink jet recording apparatus is shown in FIG. Here, a color inkjet printer that performs color printing is shown as an example of an inkjet recording apparatus. The ink jet recording apparatus 1 is provided with a carriage 3 that can reciprocate along a guide shaft 2 spanned in the print width direction (X direction in the figure). The carriage 3 is moved by driving a carriage motor (not shown) and rotating an endless belt 5 hung on a pulley 4 that transmits a driving force of the motor. The carriage 3 is mounted with a recording ink tank 6 and an ink jet head 7 below the ink tank 6 with an ink discharge port facing downward.

  The ink tank 6 is provided with ink tanks of a plurality of colors so that recording materials (inks) of a plurality of colors can be ejected from the inkjet head 7. In the present embodiment, the ink tank 6a for black and a yellow ink tank 6a are provided. An ink tank 6b, a cyan ink tank 6c, and a magenta ink tank 6d are mounted. The ink tanks 6 a to 6 d are detachably attached to the carriage 3.

  The ink-jet head 7 is arranged below the ink tanks 6a to 6d corresponding to the type of the ink tank 6, and includes a black head 7a for discharging black ink, a yellow head 7b for discharging yellow ink, A cyan head 7c that discharges cyan ink and a magenta head 7d that discharges magenta ink are included. Each inkjet head 7 is detachably provided. The ink tank 6 and the ink jet head 7 may be configured integrally, or the ink tank 6 and the ink jet head 7 are configured to be separable so that only the ink tank 6 is replaced when the ink runs out. It doesn't matter.

  Examples of ink ejection methods of the inkjet heads 7a to 7d include a piezo method that pushes out ink using a piezo element (not shown) and a thermal inkjet method that generates air bubbles by a heating element and ejects ink by applying pressure. It is done.

  The inkjet recording apparatus 1 is provided with a conveyance roller 8 that conveys a recording medium such as paper or plastic film, and the recording medium is conveyed by the conveyance roller 8 in a direction Y orthogonal to the print width direction X. The flexible cable 9 transmits and receives electrical signals between a control board attached to the back of the main body (not shown) and the inkjet head 7 mounted on the carriage 3.

  In such an ink jet recording apparatus, when a high-viscosity ink whose viscosity is lowered as the temperature rises is used as a recording material, there is an advantage that a printed image is hardly blurred and clear printing can be performed. However, if high-viscosity ink is ejected from the inkjet head as it is, pressure loss increases due to flow path resistance in the supply path, causing problems such as ink not being ejected normally, and image quality is degraded.

  In order to solve the above problems, conventionally, the ink supply system is heated using a heating means such as a heater to reduce the viscosity of the high-viscosity ink, thereby reducing the pressure loss and the ink to the inkjet head. The supply was stabilized. However, for example, when the ink in the ink tank is heated, the ink temperature may change while the supply path from the ink tank to the ink jet head, or while flowing or staying in the ink jet head, the ink viscosity may become uneven. was there.

  Therefore, a method for accurately controlling the temperature of high-viscosity ink has been proposed. For example, Patent Document 1 discloses a main tank that serves as an ink supply source and a sub-tank that is temporarily stored before being supplied to an inkjet head. Ink jet printers have been proposed in which the sub tank and the ink supply path are made of a material having low thermal conductivity (heat insulating material), and heating means are provided in the sub tank and the ink supply path. However, since the apparatus proposed in Patent Document 1 consumes electric power by the heating means, the running cost of the apparatus becomes high.

On the other hand, particularly in a high-speed ink jet recording apparatus, heat radiation from a heat generating component such as a motor or a power supply circuit that drives an ink jet head, a carriage, a pressure feed pump that pumps ink, or the like becomes a problem. For example, cooling using a cooling fan is conceivable as a method of cooling the heat-generating component. However, since a separate cooling fan is provided, the number of components and power consumption increase, leading to a cost increase. In addition, the wind noise of the cooling fan is uncomfortable for the user.
JP 2003-220715 A

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an ink jet recording apparatus that accurately controls the temperature of high-viscosity ink, stabilizes the ink viscosity, and also has a countermeasure against heat generation from heat-generating components.

In order to achieve the above object, the present invention provides an inkjet head that ejects a high-viscosity ink that decreases in viscosity as the temperature rises, a main tank that stores the high-viscosity ink, and an ink supplied to the inkjet head. An ink tank comprising a sub-tank that is housed in an automatic manner, an ink supply path that connects the sub-tank and the main tank, a pressure-feed pump that pumps high-viscosity ink from the main tank to the sub-tank via the ink supply path,
In the ink jet recording apparatus including a heating unit that heats the ink in the sub tank and a temperature sensor that detects the temperature of the ink in the sub tank, the ink supply path is configured to generate heat received from a heat generating component in the vicinity of the ink tank. A supply path switching means for switching the ink supply paths, and a control means for controlling the drive of the supply path switching means and the heating means are provided. According to the detection result of the temperature sensor, switching of the ink supply path and ON / OFF of the heating means are controlled.

  According to the present invention, in the ink jet recording apparatus having the above-described configuration, the ink supply path includes a first supply path disposed so that at least a part thereof is in contact with the heat generating component, and the heat from the heat generating component. A second supply path arranged so as not to receive, and the control means turns off the heating means when the temperature detected by the temperature sensor is within a set temperature range, and the first supply path. When the detected temperature is below the set temperature range, the heating means is turned on and the first supply path is used. When the detected temperature is above the set temperature range, the heating means is turned off. Thus, the second supply path is used.

  According to the present invention, in the ink jet recording apparatus configured as described above, the first supply path is characterized in that at least a portion in contact with the heat generating component is a metal.

  According to the first configuration of the present invention, the temperature control when the viscosity of the high-viscosity ink is lowered is easily and accurately performed by switching the plurality of ink supply paths according to the ink temperature in the sub tank. And a stable ink viscosity can be maintained. In addition, the use of heating means in the sub-tank is suppressed to the minimum necessary, and the heat-generating components can be cooled without providing a separate cooling fan, so that the power consumption of the apparatus is reduced and a space for installing a cooling fan is also provided. It becomes unnecessary.

  According to the second configuration of the present invention, in the ink jet recording apparatus having the first configuration, when the ink temperature in the sub tank is within the set temperature range, the first supply path is used to The viscosity of the high-viscosity ink is reduced using the heat of the ink, and at the same time, the ink in the first supply path is used for cooling the heat generating component. When the ink temperature falls below the set temperature range, the heat dissipation from the heat generating component and the sub tank The viscosity of the ink is sufficiently lowered using the heating means. On the other hand, when the ink temperature exceeds the set temperature range due to heat radiation from the heat-generating component, the ink viscosity can be adjusted by switching to the second supply path.

  According to the third configuration of the present invention, in the ink jet recording apparatus having the second configuration, the portion of the first supply path that contacts at least the heat-generating component is made of metal, so that the thermal conductivity of the contact portion is set. The heat exchange efficiency between the ink flowing through the first supply path and the heat-generating component can be increased.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ink jet recording apparatus 1 of the present invention. Portions common to FIG. 7 of the conventional example are denoted by the same reference numerals and description thereof is omitted. The inkjet recording apparatus 1 includes a control unit 11, and an interface 12, a ROM 13, a RAM 14, an encoder 15, a motor control circuit 16, an inkjet head control circuit 19, and the like are connected to the control unit 11.

  The interface 12 transmits / receives data to / from a host device such as a personal computer (not shown). Then, the control unit 11 outputs a control signal to various control circuits based on the print data received via the interface 12.

  The ROM 13 stores a printing program for performing printing by driving the inkjet head 7, a control program for switching an ink supply path and heating ink, which will be described later, and the like. The RAM 14 stores print data received by the control unit 11 via the interface 12 in a predetermined area.

  The encoder 15 is connected to the transport roller 8 and outputs a pulse train according to the rotational displacement amount of the rotation shaft of the transport roller 8. The control unit 11 counts the number of pulses transmitted from the encoder 15 to calculate the rotation amount and grasps the recording medium feed amount (recording medium position). Then, the control unit 11 outputs a control signal to the motor control circuit 16 and the inkjet head control circuit 19 based on the signal from the encoder 15.

  The motor control circuit 16 drives the recording medium carrying motor 17 and the carriage moving motor 18 by the output signal from the control unit 11. The recording medium transport motor 17 is driven to rotate the transport roller 8 and transport the recording medium in a direction Y (see FIG. 7) perpendicular to the paper width direction X. The carriage moving motor 18 is driven to reciprocate the carriage 3 along the guide shaft 2 (see FIG. 7).

  The inkjet head control circuit 19 transfers print data to the inkjet head 7 based on the output signal from the control unit 11, and controls ink ejection from the inkjet head 7 based on the transferred print data. By such control, control of transport of the recording medium by the transport roller 8 driven by the recording medium transport motor 17, and control of reciprocation along the guide shaft 2 of the carriage 3 by the carriage moving motor 18, to the recording medium. The printing process is performed.

  The ink tank 6 includes a main tank 20 that stores high-viscosity ink and a sub-tank 21 that is mounted on the carriage 3. The high-viscosity ink in the main tank 20 is supplied with an ink supply path and a pressure feed pump (not shown). Used to be supplied to the sub tank 21 and temporarily stored. Based on the output signal from the control unit 11, the ink is ejected from the inkjet head 7 onto the recording medium.

  FIG. 2 is a schematic diagram showing the configuration of the ink supply mechanism (region S in FIG. 1) of the inkjet recording apparatus 1 of the present invention. Portions common to FIG. 1 are denoted by the same reference numerals and description thereof is omitted. The main tank 20 and the sub tank 21 communicate with each other through two ink supply paths including a first supply path 22 and a second supply path 23. A pressure feed pump 24 is attached to the main tank 20, and supply path switching means 25 for switching between the first supply path 22 and the second supply path 23 is provided in the pressure feed pump 24.

  The first supply path 22 is disposed so that at least a part thereof is in contact with a heat generating component 26 such as a motor or a power supply circuit that drives the carriage 3, the inkjet head 7, the pumping pump 24, or the like. The contact surface between the first supply path 22 and the heat generating component 26 is made of a member having a high thermal conductivity such as metal, and heat is generated between the ink in the first supply path 22 and the heat generating component 26. Exchange is possible. On the other hand, the second supply path 23 is arranged so that the heat generating component 26 does not exist in the vicinity. The supply path switching means 25 selects either the first supply path 22 or the second supply path 23 based on the control signal from the control unit 11, and the pumping pump 24 uses the selected supply path for the sub tank. Ink is supplied into the chamber 21.

  A heater 27 for heating the ink supplied from the main tank 20 is provided in the sub tank 21, and a temperature sensor 28 for detecting the ink temperature in the sub tank 21 is additionally provided. The sub tank 21 and the inkjet head 7 are communicated with each other by an ink supply pipe 29.

  FIG. 3 is a cross-sectional view showing details of the configuration of the sub tank. First and second supply paths 22 and 23 for supplying ink from the main tank 20 (see FIG. 2) into the sub tank 21 and ink supply for supplying ink from the sub tank 21 to the inkjet head 7 (see FIG. 2). A pipe 29 is projected from the inside of the sub tank 21 to the outside. A heater 27 is disposed in the sub tank 21 so that the ink 31 stored in the sub tank 21 can be heated uniformly. A temperature sensor 28 is provided on the bottom surface of the sub tank 21 with the detection surface facing inward. The periphery of the sub-tank 21 is covered with a heat insulating material 30 so that the ink 31 accommodated therein is not affected by the surrounding heat.

  In the present invention, an ink supply path for supplying ink from the main tank 20 is selected based on the ink temperature in the sub-tank 21, and control for heating the ink in the sub-tank 21 is performed as necessary. It is what. That is, when the ink temperature in the sub-tank 21 is within the set temperature range, the first supply path 22 is used to reduce the viscosity of the high-viscosity ink using the heat from the heat generating component 26, and at the same time, The ink in one supply path 22 is used for cooling the heat generating component 26.

  In addition, when the ink temperature is equal to or lower than the set temperature range and the high-viscosity ink cannot be sufficiently reduced in viscosity only by heat radiation from the heat generating component 26, the ink is heated using the heater 27 in the sub tank 21. On the other hand, when the ink temperature becomes equal to or higher than the set temperature due to heat radiation from the heat generating component 26, the ink is supplied using the second supply path 23.

  This makes it possible to easily and accurately control the temperature when reducing the viscosity of the high-viscosity ink, and maintain a stable ink viscosity. Further, the use of the heater 27 can be suppressed to the minimum necessary, and the heat-generating component can be cooled without providing a separate cooling fan, so that the power consumption of the apparatus can be reduced and the space can be saved. The first supply path 22 does not necessarily need to be in contact with the heat generating component 26, but it is preferable that at least a part of the first supply path 22 is in contact with the heat supply efficiency of the ink and the heat generating component 26. Further, the second supply path 23 may be separated from the heat generating component 26 as shown in FIG. 2 to block the influence of heat, or a heat insulating material may be interposed between the second supply path 23 and the heat generating component 26. .

  Next, the control of the ink supply mechanism of the present invention will be specifically described. FIG. 4 is a schematic diagram showing the state transition of the ink jet recording apparatus of the present invention. Now, when the ink temperature T in the sub tank 21 detected by the temperature sensor 28 is in the range of the set temperature A ° C. to B ° C. (A> B), the first supply path 22 is used and the heater 27 is turned off ( In the standard state, the optimum ink viscosity is maintained by utilizing the heat from the heat-generating component 26.

  From this standard state, when the ink temperature T becomes A ° C. or higher due to continuous operation of the apparatus or a change in environmental temperature, the control unit 11 transmits a control signal to the supply path switching means 25, and the second supply path 22 transmits the control signal. Switch to supply path 23. That is, by using the second supply path 23 and turning off the heater 27 (state 1), the influence of the heat from the heat-generating component 26 is cut off and the decrease in ink viscosity is suppressed.

  On the other hand, when the ink temperature T falls below B ° C. due to the environmental temperature change from the standard state, the control unit 11 transmits a control signal to the heater 27 to turn on the heater 27. That is, by using the first supply path 22 and turning on the heater 27 (state 2), the ink temperature is increased using the heat of the heater 27 in addition to the heat from the heat generating component 26, and the ink viscosity is increased. Suppresses the rise.

  FIG. 5 is a flowchart showing the operation of the ink jet recording apparatus of the present invention. The image forming process will be described according to the steps in FIG. 5 with reference to FIGS. Here, in FIG. 4, the set temperature A that transitions between the standard state and the state 1 is 60 ° C., and the set temperature B that transitions between the standard state and the state 2 is 30 ° C.

  First, when image formation is started by the user (step S1), the ink temperature T in the sub tank 21 is detected by the temperature sensor 28 (step S2). Then, it is determined whether the ink temperature T is 60 ° C. or higher (step S3). If the ink temperature T is 60 ° C. or higher, it is necessary to make a transition to the state 1, so it is next determined whether or not the second supply path 23 is selected (step S4). If the second supply path 23 is not selected, a control signal is transmitted from the control unit 11 to the supply path switching means 25, and the first supply path 22 is switched to the second supply path 23 (step S5). ). On the other hand, if the second supply path 23 has already been selected in step S4, the process proceeds directly to the next step.

  Next, it is determined whether or not the heater 27 is in an OFF state (step S6). If the heater 27 is in an ON state, a control signal is transmitted from the control unit 11 to the heater 27 to turn off the heater 27 (step S7). ). On the other hand, if the heater 27 is already OFF in step S7, the process proceeds to the next step as it is.

  If the ink temperature T is lower than 60 ° C. in step S3, it is necessary to transition to the standard state or state 2, so it is next determined whether or not the first supply path 22 is selected (step S8). ). If the first supply path 22 is not selected, a control signal is transmitted from the control unit 11 to the supply path switching means 25, and the second supply path 23 is switched to the first supply path 22 (step S9). ). On the other hand, if the first supply path 22 has already been selected in step S8, the process proceeds directly to the next step.

  Next, it is determined whether or not the ink temperature T is 30 ° C. or less (step S10). When the ink temperature T is 30 ° C. or lower, since it is necessary to make a transition to the state 2, it is determined whether or not the heater 27 is in the OFF state (step S11). Is sent to the heater 27 to turn on the heater 27 (step S12). On the other hand, if the heater 27 is already ON in step S11, the process proceeds to the next step as it is.

  If the ink temperature T is higher than 30 ° C. in step S10, it is necessary to transition to the standard state. Therefore, it is determined whether or not the heater 27 is in the OFF state (step S13). A control signal is transmitted from the control unit 11 to the heater 27 to turn off the heater 27 (step S14). On the other hand, if the heater 27 is already in the OFF state in step S13, the process proceeds to the next step as it is.

  Then, the ink is supplied from the main tank 20 through the first supply path 22 or the second supply path 23 into the sub tank 21 by the pressure feed pump 24 (step S15). Further, ink is ejected from the inkjet head 7 based on the print data received via the interface 12 (step S16), and an image is formed at a predetermined location on the recording medium. Finally, it is determined whether or not the image forming process has been completed (step S17). If the process continues, the process returns to step S2 and the same procedure is repeated (steps S2 to S16).

  Here, the set temperatures A and B are used as reference values for the transition between the standard state and the state 1 or the state 2, but for example, as shown in FIG. 6, three temperatures A, B, and C ( A> B> C, for example, A = 60 ° C., B = 45 ° C., C = 30 ° C.) When the temperature is higher than the set temperature A, the standard state is changed to the state 1. When the temperature is lower than the set temperature B, the state 1 is changed to the standard state. It is good also as control which changes to the standard state from the standard state when the temperature is equal to or lower than the set temperature C, and changes from the state 2 to the standard state when the temperature is equal to or higher than the set temperature B.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, the ink viscosity is adjusted by switching the two ink supply paths, the first supply path 22 and the second supply path 23, but the influence of heat received from the heat generating component 26 is affected. Three or more different supply paths may be provided, and one of the supply paths may be selected by the supply path switching unit 25 according to the ink temperature.

  In FIG. 1, input from the user is input from the outside of the personal computer or the like via the interface 12. However, the present invention is not limited thereto, and input is performed using an operation panel or the like provided in the inkjet recording apparatus 1. It doesn't matter. Of course, the present invention can be applied not only to a color inkjet printer but also to a monochrome inkjet printer.

  The present invention comprises an inkjet head that discharges high-viscosity ink that decreases in viscosity as the temperature rises, a main tank that stores high-viscosity ink, and a sub-tank that temporarily stores ink supplied to the inkjet head. An ink tank, an ink supply path that connects the sub tank and the main tank, a pressure feed pump that pumps high viscosity ink from the main tank to the sub tank via the ink supply path, a heating unit that heats the ink in the sub tank, and a sub tank In an ink jet recording apparatus comprising a temperature sensor for detecting the ink temperature in the ink supply path, the ink supply path is composed of a plurality of supply paths that are affected by heat from the heat generating components in the vicinity of the ink tank. Path switching means and control means for controlling driving of the supply path switching means and heating means Is provided, the control means controls the ON / OFF switching and heating means of the ink supply path in accordance with the detection result of the temperature sensor.

  Thus, an ink jet recording apparatus capable of easily and accurately performing temperature control when reducing the viscosity of high viscosity ink by switching the ink supply path from the main tank to the sub tank and maintaining a stable ink viscosity is provided. . In addition, the use of heat dissipation from the heat generating parts can minimize the use of a heater that heats the ink in the sub-tank, and further heat is dissipated from the heat generating parts to the ink via the ink supply path. Heating components can be cooled without providing a fan, etc., contributing to low running costs and space savings.

  In addition, since the ink supply path is composed of the first supply path arranged so as to be in contact with the heat generating component and the second supply path arranged so as not to be affected by heat from the heat generating component, The configuration of the control and device is further simplified. Furthermore, if the contact portion between the first supply path and the heat generating component is made of metal, heat exchange between the ink and the heat generating component in the first supply path can be performed more efficiently.

These are block diagrams which show the structure of the inkjet recording device of this embodiment. These are schematic diagrams showing the configuration of the ink supply mechanism of the ink jet recording apparatus of the present invention. These are sectional views showing details of the configuration of a sub-tank used in the ink jet recording apparatus of the present invention. These are the schematic diagrams showing the state transition of the inkjet recording device of this invention. These are flowcharts which show operation | movement of the inkjet recording device of this embodiment. These are the schematic diagrams showing the other example of the state transition of the inkjet recording device of this invention. These are the schematic perspective views which show the structure of the conventional inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 3 Carriage 6 Ink tank 7 Inkjet head 11 Control part (control means)
DESCRIPTION OF SYMBOLS 20 Main tank 21 Subtank 22 1st supply path 23 2nd supply path 24 Pressure feed pump 25 Supply path switching means 26 Heat generating component 27 Heater (heating means)
28 Temperature sensor

Claims (3)

An inkjet head that discharges high-viscosity ink that decreases in viscosity as the temperature rises;
An ink tank comprising a main tank for storing high-viscosity ink and a sub-tank for temporarily storing ink supplied to the inkjet head;
An ink supply path connecting the sub tank and the main tank;
A pressure-feed pump that pumps high-viscosity ink from the main tank to the sub-tank via the ink supply path;
Heating means for heating the ink in the sub tank;
In an ink jet recording apparatus comprising: a temperature sensor that detects an ink temperature in the sub tank;
The ink supply path is composed of a plurality of supply paths having different influences of heat received from heat generating components in the vicinity of the ink tank. The supply path switching means for switching the ink supply paths, and the drive of the supply path switching means and the heating means Control means for controlling the ink jet recording, wherein the control means controls switching of the ink supply path and ON / OFF of the heating means in accordance with a detection result of the temperature sensor. apparatus.   The ink supply path includes a first supply path disposed so that at least a part thereof is in contact with the heat generating component, and a second supply path disposed so as not to be affected by heat from the heat generating component. When the detected temperature of the temperature sensor is within the set temperature range, the control means uses the first supply path with the heating means turned off, and the detected temperature is below the set temperature range. Wherein the heating means is turned on and the first supply path is used, and when the detected temperature is equal to or higher than a set temperature range, the heating means is turned off and the second supply path is used. The inkjet recording apparatus according to claim 1.   The inkjet recording apparatus according to claim 2, wherein at least a portion of the first supply path that contacts the heat generating component is a metal.

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