JP2008110588A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder which implements the quick start up while improving the energy efficiency. <P>SOLUTION: An ink feeding system is equipped with a plurality of heaters comprising a main heater H1, a subtank heater H2, the 2nd feed heater H3 and a head heater H4. A temperature control section 201 performs the controlling of ON/OFF of each heater based on the detection result of a temperature detector 30. The heater installed in the member in the downstream of the ink feeding is set to be ON by the temperature control section 201 even at a high temperature. That is, for example, the main tank heater H1 is turned ON only in the case of the temperature becomes lower than the one at which the subtank heater H2 becomes ON. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that records an image (including characters, drawings, symbols, and the like) on a recording medium by ejecting ink droplets toward a recording medium such as paper.

  The temperature of the ink is one of the important factors that influence the viscosity of the ink. In addition, in an ink jet recording apparatus such as a printer, if the ink viscosity deviates from a predetermined appropriate range, a problem may occur in ink ejection from the recording head. That is, for good image recording, it is important to keep the ink temperature in an appropriate range.

In Patent Document 1, the temperature for monitoring the temperature of an ink supply system, that is, an ink tank that stores ink, a recording head that discharges the ink onto a recording medium, and a supply path that supplies ink from the ink tank to the recording head. In addition to providing monitoring means, a heater for heating the ink supply system is provided.
JP 2003-220714 A (published on August 5, 2003)

  In Patent Document 1, since the main tank is not provided with a heater, the time until the ink reaches the allowable temperature range from the low temperature state to the use at the time of start-up after being turned off for a long time in winter is used. Becomes longer. That is, during this time, the ink jet recording apparatus cannot be used, and the waiting time becomes long.

  On the other hand, if the main tank is also provided with a heater, the main tank has a larger ink capacity than other parts of the ink supply system, so that the power consumption of the heater until the ink in the main tank reaches the allowable temperature range increases. .

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus that suppresses an increase in energy consumption and realizes a quick rise.

  In order to solve the above problems, an ink jet recording apparatus according to the present invention is an ink jet recording apparatus that records an image on a recording medium with ink, the main tank storing the ink, and discharging the ink onto the recording medium. An ink supply system including a recording head that supplies the ink in the main tank to the recording head, and a heating unit that is provided in plural along the ink supply direction of the ink supply system and that can heat the ink. A temperature detection unit that detects a temperature in the ink jet recording apparatus, and the heating unit heats the ink when the detection result of the temperature detection unit becomes lower than a predetermined temperature, and performs individual heating. The predetermined temperature is set higher as the part is arranged on the downstream side.

  Thus, the heating unit that heats the portion near the recording head heats the ink even at a higher temperature than the heating unit that heats the far portion. That is, the entire ink supply system is not always heated, but the vicinity of the recording head is preferentially heated. Therefore, the temperature around the recording head can be raised to a temperature at which image formation can be performed quickly without increasing energy consumption.

  According to a second aspect of the present invention, in the inkjet recording apparatus according to the first aspect, the heating unit provided on the most downstream side in the ink supply direction among the heating units heats the ink in the recording head. You may come to do.

  According to a third aspect of the present invention, in the ink jet recording apparatus according to the first or second aspect, the supply unit is smaller than the main tank and temporarily stores ink from the main tank toward the recording head. There may be provided an auxiliary tank, a first flow path provided between the main tank and the auxiliary tank, and a second flow path provided between the auxiliary tank and the recording head.

  According to a fourth aspect of the present invention, in the inkjet recording apparatus according to the third aspect of the present invention, the heating unit is at least one in the main tank, the first channel, the auxiliary tank, the second channel, and the recording head. It may be provided one by one.

  According to the ink jet recording apparatus of the present invention, the entire ink supply system is not always heated, but the vicinity of the recording head is preferentially heated. Therefore, the temperature around the recording head can be raised to a temperature at which image formation can be performed quickly without increasing energy consumption.

  The ink jet recording apparatus of the present invention will be specifically described by showing its embodiment. However, the present invention is not limited to the following description.

[1] Inkjet Printer As an inkjet recording apparatus, a line type inkjet printer provided with a head having a number of nozzles will be described below as an example, but the present invention is not limited to this.

  As the line-type ink jet printer, the technique described in JP-A-2006-12397 (published on May 18, 2006) can be suitably used. An example of the structure of a line type ink jet printer is shown in FIGS. FIG. 1 is a front view showing the main configuration of the ink jet printer, and FIG. 2 is a plan view showing the structure around the head as viewed from the ink ejection surface side. In FIG. 2, for convenience of explanation, the conveyor belt 111 is indicated by a dotted line.

  A printer 100 shown in FIG. 1 is a line head type color ink jet printer having four heads 12 arranged in the transport direction of the printing paper P. Each head 12 has a rectangular outer shape that is elongated in a direction orthogonal to the conveyance direction of the paper P (a direction perpendicular to the paper surface in the drawing). The printer 100 is provided with a paper feeding device 114 on the lower side, a paper receiving unit 116 on the upper side, and a transport unit 120 on the middle in the installation posture. Further, the printer 100 includes a control device 200 that controls these operations.

  The paper feeding device 114 is a paper storage unit 115 that can store a plurality of stacked rectangular papers P, and a paper supply unit that feeds the uppermost paper P in the paper storage unit 115 to the transport unit 120 one by one. And a roller 145. In the paper storage unit 115, the paper P is stored so as to be fed in a direction parallel to the long side. A plurality of feed rollers 118 are appropriately disposed along the transport path between the paper storage unit 115 and the transport unit 120. The printing paper P discharged from the paper feeding device 114 is sent to the transport unit 120 by the feed roller 118 with one short side as the leading edge.

  The transport unit 120 includes an endless transport belt 111 and a plurality of belt rollers 106 around which the transport belt 111 is wound. A predetermined tension is generated on the conveyor belt 111 wound between the individual belt rollers 106. Also, one surface (conveying surface 127) of the conveying belt 111 is treated with adhesive silicon rubber, and the printing paper P is securely adhered to the conveying surface 127. Alternatively, a large number of small-diameter holes are formed in the transport belt 111, and suction means such as a fan for sucking air from the opposite side of the surface of the transport belt 111 on which the printing paper P is held is provided. It is good also as a structure hold | maintained at the conveyance belt 111 by the suction force of. Further, the transport surface 127 is arranged so as to face the head 12. The printing paper P sent out from the paper feeding device 114 is transported by the transport belt 111 while being printed by the head 12 on the upper surface (printing surface), and reaches the paper receiving section 116. In the paper receiving unit 116, a plurality of printed printing papers P are placed so as to overlap each other.

  The four heads 12 are arranged close to each other along the paper transport direction. A large number of nozzles 8 having a minute diameter are provided on the bottom surfaces (ejection surfaces 13) of the four heads 12 (see FIG. 2). The ink color ejected from the nozzle 8 is one of magenta (M), yellow (Y), cyan (C), and black (K), and is ejected from a number of nozzles 8 belonging to the same head 12. The color is the same. In addition, inks of different colors selected from the four colors magenta, yellow, cyan, and black are ejected from a large number of ink ejection ports belonging to the four heads 12.

  A slight gap is formed between the discharge surface 13 and the transport surface 127 of the transport belt 111. The printing paper P is transported along the transport direction indicated by the arrows with this gap. When the printing paper P sequentially passes below the ejection surface 13, a desired color image is formed on the printing paper P by ejecting ink from the nozzles 8 according to the image data toward the upper surface of the printing paper P. Is done.

  A peeling plate 140 is provided downstream of the transport unit 120 in the paper transport direction. The peeling plate 140 peels the printing paper P adhered to the conveyance surface 127 of the conveyance belt 111 from the conveyance surface 127 when the end of the conveyance unit 120 enters between the printing paper P and the conveyance belt 111. To do.

  A plurality of feed rollers 121 are arranged between the transport unit 120 and the paper receiver 116. The printing paper P discharged from the transport unit 120 is sent to the paper receiving unit 116 by the feed roller 121.

  A paper surface sensor 133, which is an optical sensor composed of a light emitting element and a light receiving element, is detected upstream of the head 12, which is the most upstream in the conveying direction, in order to detect the leading end position of the printing paper P on the conveying belt 111. Has been placed. Since it can be seen from the output signal from the paper surface sensor 133 that the leading edge of the printing paper P has reached the detection position, an ejection signal is supplied from the control device 200 to the head 12 accordingly. Thus, an image is formed on the printing paper P with ink. This image includes characters, symbols, figures, and the like.

  The control device 200 transmits / receives data signals and control signals to / from each unit of the printer 100 in accordance with instructions received from the user via an operation panel (not shown) and detection results of various sensors, thereby performing image forming operations, It controls the ink temperature adjustment operation and the like which will be described later. Specifically, the control device 200 can be configured by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU can perform various calculations and execute programs. The ROM stores a program related to control performed by the CPU, a program related to the operation of each unit in the printer 100, and the like. In addition to functioning as a work area for the CPU, the RAM has an area for holding user input contents and the like.

  In addition, the printer 100 is provided with a temperature detector 30 that detects the temperature in the apparatus of the printer 100. Since the temperature detection unit 30 is used for the ink temperature adjustment operation, it is preferable that the temperature detection unit 30 is provided in the vicinity of the main tank 21 described later in order to achieve more accurate ink temperature adjustment. In the present embodiment, the temperature detector 30 detects the temperature inside the printer 100.

[2] Ink supply system In this embodiment, the head 12, the main tank 21 for storing ink, the sub tank 22 provided between the main tank 21 and the head 12, and the ink from the main tank 21 to the sub tank are supplied. A first supply path 23 for supplying, a second supply path 24 for supplying ink from the sub tank 22 to the head 12, and a pump 25 provided in the supply path 23 for sending ink from the main tank 21 to the sub tank 22. The ink supply system 20 is formed.

  The main tank 21 is provided with a vent hole 31 through which air flows from the outside as the ink inside the main tank 21 decreases. The printer 100 is detachably provided. When the ink remaining amount sensor (not shown) detects that the ink in the main tank 21 is low, the control unit 200 prompts the user to replace the tank with a display unit (not shown).

  Similar to the main tank 21, the sub tank 22 includes a vent hole 32 through which air flows from the outside as the ink inside decreases. The sub tank 22 has a smaller ink capacity than the main tank 21. The sub tank 22 stores the ink from the main tank 21 and maintains the difference between the ink head in the sub tank 22 and the ink head in the head 12, that is, the water head difference D, so that the amount of ink supplied to the head 12 is maintained. Can be adjusted. The sub tank 22 is provided with an ink amount sensor 33 for the sub tank, and the detection result of the ink amount sensor 33 is sent to the control device 200.

  The ink supply system 20 is provided with a heater for warming the ink. As shown in FIG. 3, in this embodiment, the ink supply system 20 includes a main tank heater H1 that warms the ink in the main tank 21, a sub tank heater H2 that warms the ink in the sub tank 22, and the ink in the second supply path 24. Is provided with a second supply path heater H3 for heating the ink and a head heater H4 for heating the ink in the head 12. These heaters H <b> 1 to H <b> 4 heat the ink in each part by applying heat to the outer surface of each part of the ink supply system 20.

  A first supply path heater that warms the ink in the first supply path 23 may be further provided. However, since the ink flows into the first supply path 23 only while the pump 25 is operating, the heater is There is no need to provide it.

[3] Ink Temperature Adjustment The ink temperature adjustment of the printer 100 will be specifically described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram showing the flow of signals during the ink temperature adjustment operation, and FIG. 5 is a flowchart of the ink temperature adjustment operation.

  As shown in FIG. 4, the control device 200 includes a temperature control unit 201 and a storage unit (not shown). This storage unit stores a heating time table 202 in the storage unit. In addition to this, the control device 200 may include a supply control unit and the like. The supply control unit can control the motor of the pump 25 based on the detection result of the ink amount sensor 201 for sub tank ink, and can supply ink from the main tank 21 to the sub tank 22.

  The temperature control unit 201 can adjust the temperature of the ink in the ink supply system 20 to an appropriate range by controlling ON / OFF of the heaters H <b> 1 to H <b> 4 based on the detection result of the temperature detector 30. it can. The temperature control unit 201 individually has reference values L1 to L4 for the main tank heater H1, the sub tank heater H2, the second supply path heater H3, and the head heater H4. The reference value L1 <L2 <L3 <L4 is satisfied. When the detected temperature T of the temperature detector 30 falls below any of the reference values L1 to L4, the heater corresponding to the reference value is turned on. That is, the temperature control unit 201 does not lower the temperature of the heater provided more upstream in the ink supply direction of the ink supply system 20 (the direction from the main tank 21 toward the head 12, indicated by the arrow in FIG. 3). Do not turn on. The temperature control unit 201 is configured to turn on the heater provided downstream even at a relatively high temperature.

  These reference values L1 to L4 are not limited to specific values, and depend on the installation environment of the printer 1, the configuration of the printer 1 (nozzle size, droplet discharge speed, etc.), the type of ink, and the like. It can be changed as appropriate. In this embodiment, L1 is 5 ° C, L2 is 10 ° C, L3 is 15 ° C, and L4 is 20 ° C.

  Further, the appropriate range of the ink temperature differs depending on the type of ink, the configuration of the printer 1, and the like, and is not limited to a specific value. In the present embodiment, it is assumed that the range of 20 ° C. to 50 ° C. is an appropriate range.

  In the present embodiment, it is assumed that the control device 100 performs this ink adjustment operation when the printer 100 is turned on, or when returning from the low power mode for reducing the power consumption of the device. However, besides this, the detection result of the temperature detector 30 may be constantly monitored, and the ink temperature adjustment operation may be performed based on the detection result.

  In the present embodiment, the temperature control unit 201 is configured to turn off when a predetermined time elapses after the heaters (H1 to H4) are turned on.

  Therefore, the printer 100 further includes a timer group 203. The four timers included in the timer group 203 are provided so as to correspond to the main tank heater H1, the sub tank heater H2, the second supply path heater H3, and the head heater H4, respectively. When the heater (any one of H1 to H4) is turned on, the corresponding timers of the timer 203 group are also turned on by the control unit 200, and the counting of the heating time is started. When each timer counts a predetermined time set in advance, the temperature control unit 201 switches off the heater corresponding to this timer.

  This predetermined time is the set time m recorded in the heating time table 202. The heating time table 202 shows the temperature T in the printer 100 and the set time m required for setting the ink temperature within an appropriate range in association with each other. FIG. 6 shows a specific example of the heating time table. This table shows that the target ink temperature is 20 ° C., and when the temperature is 5 ° C., the ink temperature reaches 20 ° C. if heating is performed for 5 minutes.

  The set time m varies depending on the target ink temperature. 6 shows the table 202 in which the temperature T and the set time m have a one-to-one correspondence. However, the table 202 is not limited to this, and has a plurality of target ink temperatures. It may have a plurality of set times m so as to correspond to each target temperature.

  Further, the above-described storage unit (not shown) stores a plurality of heating time tables 202 corresponding to the respective timers of the timer group 203, that is, corresponding to the respective heaters (H1 to H4). Each heating time table 202 has a different set time m. In other words, different set times m are set for the heaters (H1 to H4).

  Here, the set time m corresponding to the timer corresponding to the main tank heater H1 may be changed according to the amount of ink in the main tank 21. In this case, the temperature control unit 201 may increase the set time m as the amount of ink in the main tank 21 increases.

  Also, the heat capacities of the heaters that heat each heating object are made different so that the heaters (H1 to H4) have the same time for raising the temperature of the heating object (main tank 21 or the like) to a specified value. Also good. That is, the heat capacity of the heater that heats it may be increased as the internal capacity of the heating target increases. In this way, when two or more heaters are turned on, the heaters can be turned off simultaneously. In this case, one timer is sufficient.

  In particular, since the amount of ink in the main tank heater H1 varies greatly, the heat capacity of the main tank heater H1 is preferably variable according to the amount of ink in the main tank 21. That is, it is preferable that the heat capacity of the main tank heater H1 can be reduced as the amount of ink in the main tank 21 decreases.

  Hereinafter, a specific example of the temperature adjustment operation will be described with reference to FIG.

  First, the control device 200 reads the detection result of the temperature detector 30 (S1).

  When the detection result T indicates that the temperature is less than 5 ° C. (reference value L1), the temperature control unit 201 turns on all of the main tank heater H1, the sub tank heater H2, the second supply path heater H3, and the head heater H4 (in S2). Yes → S3). At this time, all the timers 203 are turned on, and the heating is continued until the heating time reaches the set time m (No in S4 → S5 → S6). When the heating time reaches the set time m, the timer 203 group is cleared, the heaters H1 to H4 are turned off, and the operation is terminated (Yes in S5 → S7 → S8). Since printing is possible thereafter, printing is executed in accordance with a printing instruction from the user.

  On the other hand, when the temperature T is 5 ° C. (reference value L1) or more and less than 10 ° C. (reference value L2), only the main tank heater H1 is turned off and the other three heaters H2 to H4 are turned on (in S2). No → Yes in S9 → S10). Then, counting by the timer corresponding to the heater turned on in the timer group 203 is started. Thereafter, as described above, the heating is continued until the heating time reaches the set time m.

  If the temperature T is 10 ° C. (reference value L2) or more and less than 15 ° C. (reference value L3), the main tank heater H1 and the sub tank heater H2 are turned off, and the latter two heaters H3 and H4 are turned on. Heating is performed until the heating time of the heater reaches the set time m (No in S2 and S9 → Yes in S11 → S12).

  If the temperature T is 15 ° C. (reference value L3) or more and less than 20 ° C. (reference value L4), only the head heater H4 is turned on and heating is performed until the heating time of the head heater H4 reaches the set time m ( No in S2, S9, and S11, Yes in S13, and then S14).

When the temperature T is 20 ° C. or higher, the operation ends with all the heaters turned off (No in S2, S9, S11, and S13 → S8).
In the present embodiment, the heating is stopped when the heating time reaches the set time m, but the present invention is not limited to this. For example, a temperature sensor that detects the temperature of the internal ink is attached to each of the main tank 21 and the sub tank 22, and the temperature control unit 201 heats if the temperature sensor detects a predetermined temperature (for example, 20 ° C.) or higher. You may come to stop. In addition, a temperature sensor for measuring the temperature of the second supply path 24 or the head 12 itself is provided, and the temperature control unit 201 stops heating when the temperature sensor detects a predetermined temperature (for example, 20 ° C.) or higher. It may be.

  Further, in the flow shown in FIG. 5, even if the heating time does not reach the set time m, the temperature in the printer 100, the member such as the main tank 21, or the temperature inside these is the upper limit (for example, 45 ° C.). The temperature control unit 201 may be calibrated so as to stop heating when the temperature exceeds.

  In particular, line-type ink jet printers have a structure that allows ink to pass through a narrow flow path, so that ejection failures such as nozzle clogging and the speed or direction of ejected droplets are likely to occur. .

  The ink ejected by the ink jet recording apparatus is not particularly limited in terms of its properties and configuration, such as aqueous, oily, a solution in which a dye is dissolved, or a dispersion in which particles such as pigment are dispersed. In particular, in an ink which is a dispersion liquid in which a pigment is dispersed in a liquid, there is a demand for increasing the pigment concentration in order to obtain a high-quality image. However, on the other hand, when the pigment concentration is increased, the viscosity increases and discharge failure is likely to occur.

  Even under these conditions where liquid ejection defects are likely to occur, according to the configuration of the present embodiment, it is possible to preferentially warm ink from a portion near the head 12 of the ink supply system 20, thereby shortening the heating time. However, such a discharge failure is unlikely to occur.

  As described above, the items described in the different columns can be appropriately combined with each other, and known techniques can also be combined. It goes without saying that the technique thus obtained is also included in the present invention.

1 is a front view showing a main configuration of a printer 100 according to an embodiment of the present invention. FIG. 4 is a plan view showing a structure around a head viewed from the ink ejection surface side. FIG. 2 is a front view showing the configuration of an ink supply system 20 and its surroundings. 3 is a block diagram illustrating a signal flow during a temperature adjustment operation in the printer 100. FIG. 4 is a flowchart illustrating a processing flow during a temperature adjustment operation in the printer. It is drawing which shows an example of a heating time table.

Claims (4)

An ink jet recording apparatus that records an image on a recording medium with ink,
An ink supply system comprising: a main tank in which ink is stored; a recording head that discharges the ink to a recording medium; and a supply unit that supplies the ink in the main tank to the recording head;
A plurality of heating units provided along the ink supply direction of the ink supply system and capable of heating the ink;
A temperature detection unit for detecting the temperature in the inkjet recording apparatus,
The heating unit heats the ink when the detection result of the temperature detection unit is lower than a predetermined temperature,
Each of the heating units is an ink jet recording apparatus in which the predetermined temperature is set higher as it is arranged on the downstream side.   2. The ink jet recording apparatus according to claim 1, wherein a heating unit provided on the most downstream side in the ink supply direction among the heating units heats ink in the recording head. The supply section is
An auxiliary tank that is smaller than the main tank and temporarily stores ink from the main tank toward the recording head;
A first flow path provided between the main tank and the auxiliary tank;
A second flow path provided between the auxiliary tank and the recording head;
An ink jet recording apparatus according to claim 1 or 2.   The inkjet recording apparatus according to claim 3, wherein at least one heating unit is provided in each of the main tank, the first channel, the auxiliary tank, the second channel, and the recording head.

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