JP5615575B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an inkjet printer.

  The ink jet printer supplies ink to an ink jet head from an ink tank that stores ink, and discharges the supplied ink from the ink jet head to a recording medium, thereby forming a desired image. It is known that the viscosity of an ink changes depending on the temperature, for example, the viscosity increases at a temperature lower than a high temperature. Further, since the ink jet head has different ejection performance depending on the viscosity of the ink, the ink use temperature range is determined and used.

  When the viscosity of the ink does not match the characteristics of the ink jet head, the viscosity of the ink is adjusted by taking advantage of the characteristics of the ink. In such a case, there is an ink jet printer in which a sub tank is provided between an ink tank and an ink jet head and a heater is disposed in the sub tank, as in the technique described in Japanese Patent Application Laid-Open No. 2003-341027. This ink jet printer reduces the viscosity of the ink by heating the ink in the sub tank, and supplies the ink to the ink jet head. A heater is arranged on the outer periphery of the ink container of the sub tank and covered with a metal having good heat conduction.

JP-A-2003-341027

  In the prior art, at least a part of the ink supply system is heated to adjust the temperature of the ink. Therefore, it is necessary to use a material having good thermal conductivity for the contact between the heater and the ink supply system installed in the ink supply system. There is a problem that the material of the ink supply path is limited to some extent. In addition, when using a material with high thermal conductivity, there is a problem that heat loss occurs because it is easily affected by disturbances such as airflow and environmental temperature. In addition, a material with high thermal conductivity has poor heat retention due to heat dissipation, and heat loss due to the heat loss is large. Therefore, the heater ON time at the time of ink temperature adjustment becomes long, and power is wasted.

  In such a heating method, since it takes time to adjust the ink temperature due to heat loss, the temperature adjustment time during warm-up becomes longer, and the recovery time for the ink temperature drop due to ink supply during printing becomes longer. Furthermore, when the temperature drop is large, it is necessary to interrupt the printing and raise the ink temperature in the sub tank, which causes a problem that the printing speed is lowered.

  Further, in the heating method, when installing the heater, the space is necessarily required, and it is difficult to save the space.

In order to solve the above problems, an ink jet printer of the present invention is supplied with the ink from a main tank that stores ink whose viscosity decreases as the temperature rises, and a sub tank that temporarily stores the ink; An ink jet head that receives ink supply and discharges the ink, an ink supply path that connects the sub tank and the ink jet head, a heat dissipating means that is disposed in the sub tank and is in contact with the ink, and heats the heat dissipating means Heating means, a temperature detection sensor for measuring the temperature of the ink in the sub-tank, and control for controlling the heating means based on the temperature detected by the temperature detection sensor to maintain the ink in a predetermined temperature range in the ink jet printer and a control means for the said sub-tank The heating means is filled in a gap between the U-shaped shield pipe, the heater wire passing through the shield pipe, and the shield pipe and the heater wire. A heat-conducting filler, and the heat dissipating means includes a pair of heat dissipating metal plates in which the U-shaped concavities for arranging the shield pipes are formed. The shield pipe is disposed, the temperature detection sensor is disposed at a position sandwiched between two straight portions of the U-shaped recess between the heat radiating metal plates, and the shield pipe, the temperature detection sensor, and the heat dissipation. The heat conductive filler is disposed in the gap to thermally connect the sheet metal, and a harness for connecting the heater wire to the control means at two openings at the end of the shield pipe; A connector for connecting the heater wire is disposed, and the heat dissipating means has a fixing portion bent so that a portion corresponding to the opening covers the opening, and is attachable to and detachable from the sub tank. When the heat dissipating means is inserted and fixed in the sub tank, the O is disposed around the opening by the periphery of the fixing portion and the opening of the sub tank so that the ink from the sub tank does not leak. It is hermetically sealed by inserting a ring .

  In the present invention, by using a method of directly heating the high viscosity ink in the sub tank, it is possible to heat the high viscosity ink without heat loss. Therefore, the degree of freedom of the material of the sub tank casing is increased, and by selecting a low thermal conductivity material, it is possible to obtain a sub tank which is not affected by disturbances such as environmental temperature and air flow and has excellent heat retention. .

  Further, by installing the sub tank heater in the sub tank, the heater installation space that was originally provided is not required, and thus space saving is possible.

  Further, by inserting the sub tank heater directly into the sub tank, heat can be directly transmitted to the high viscosity ink, and the sub tank temperature detection sensor is also installed in the sub tank, so that more accurate temperature detection can be performed. For this reason, it is possible to ensure more accurate printing stability.

  When a low heat conductive material, that is, a heat insulating material is arranged around the housing of the sub tank, the energy used for heating the high viscosity ink can be reduced, and the power can be saved.

  Further, since heat is directly transferred to the high-viscosity ink, the warming-up time and the ink temperature drop recovery time due to ink supply during printing can be shortened, so the running cost can be reduced.

  When a plurality of insertion ports for inserting the sub tank heater are prepared in the sub tank, the heater can be easily added, the heater can be easily attached and detached, and the maintenance of the sub tank heater is facilitated.

  An inkjet printer forms an image with multiple colors such as Y (yellow), M (magenta), and C (cyan). However, depending on the printed image, not all colors may be used. By attaching the subtank heater to the subtank of the color used, the amount of heat given to one subtank can be increased, the warm-up time can be shortened, the printing speed is increased, the ink drop amount is increased, and the ink droplet is enlarged. It is possible to shorten the rise time of the ink temperature in the sub-tank at the time of ink supply to the sub-tank in ink supply by various printing methods.

  In addition, when the IH heater method using a heating conductor and an induction coil is used, wiring in the ink tank is not required, and space can be saved, and the heating conductor is heated by the induction coil to save heat conversion efficiency. Electricity is also possible.

FIG. 1 is a control block diagram of the ink jet printer according to the present embodiment. FIG. 2 is a schematic diagram of the ink jet printer according to the present embodiment. FIG. 3 is a schematic diagram of an ink supply path for one color. FIG. 4 is a flowchart of sub-tank ink temperature control in this embodiment. FIG. 5 is a flowchart of ink temperature control before the printing start of the inkjet head in the present embodiment. FIG. 6 is a control flowchart of the head heater according to this embodiment. FIG. 7 is a control flowchart for detecting the amount of liquid in the sub tank. FIG. 8 is a schematic view of the sub tank heater of the present embodiment. FIG. 9 is an installation view of the sub tank heater. FIG. 10 is a schematic view showing another form of the sub tank heater. FIG. 11 is a configuration diagram between the sub tank and the ink jet head when the deaeration unit is mounted.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a control block diagram of the ink jet printer according to the present embodiment. The ink jet printer is provided with a control unit 11. The control unit 11 includes an interface 12, a RAM 13, a ROM 14, a transport motor encoder 15, a motor control circuit 16, a sub tank control circuit 6, an ink supply circuit 18, and a pressure adjustment motor drive circuit. 4. A pressure sensor 27 and an inkjet head control circuit 21 are connected.

  The interface 12 performs data transmission / reception with 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 14 records a program for controlling the entire inkjet printer, such as a printing program when the inkjet head 19 is driven to perform printing, and a control program for various actuators described later. The RAM 13 stores primary information and a work area for computation, and print data received by the control unit 11 via the interface 12 in a predetermined area.

  The conveyance motor encoder 15 is connected to the recording medium conveyance motor 20 and outputs a pulse train according to the amount of rotational variation of the rotation shaft of the recording medium conveyance motor 20. The control unit 11 calculates the rotation amount by counting the number of pulses output from the conveyance motor encoder 15, grasps the feed amount of the recording medium 9, and stores it in the RAM 13. Then, the control unit 11 outputs a control signal to the motor control circuit 16 and the inkjet head drive circuit 21 based on the signal from the transport motor encoder 15.

  The motor control circuit 16 drives the recording medium transport motor 20 and the carriage drive motor 22 by the output signal from the control unit 11. By driving the recording medium conveyance motor 20, the recording medium conveyance roller 23 installed on the rotation shaft rotates and conveys the recording medium 9 in the direction X perpendicular to the paper width direction Y. The motor control circuit 16 drives the carriage drive motor 22 by an output signal from the control unit 11 to reciprocate the carriage 24 along the rail 8.

  The sub tank control circuit 6 is a control circuit that controls the sub tank heater 5, the liquid amount sensor 26, the sub tank temperature detection sensor 10, and the like installed in the sub tank 2. The sub tank control circuit 6 is connected to a sub tank heater drive circuit 43, a sub tank temperature detection circuit 44, and a liquid amount sensor detection circuit 49. The sub tank control circuit 6 performs each control of the sub tank 2. First, the ink amount in the sub tank 2 is detected by the liquid amount sensor 26 and output to the liquid amount sensor detection circuit 49. The liquid amount sensor detection circuit 49 outputs the detected amount to the control unit 11. Here, when the ink amount is not full, the sub tank control circuit 6 drives the ink supply circuit 18 via the control unit 11 to supply the high viscosity ink from the main tank 29 to the sub tank 2, and the ink in the sub tank 2. Fill up the amount. At the same time as detecting the amount of ink in the sub tank, the control unit 11 controls the pressure adjustment motor drive circuit 4 and drives the pressure adjustment motor 35 based on the value output from the pressure sensor 27, so that the sub tank 2. The internal pressure is controlled to be a predetermined pressure. That is, the ink head value is controlled to an appropriate value.

  Further, as soon as the ink in the sub tank 2 becomes full, the sub tank control circuit 6 receives the output from the sub tank temperature detection sensor 10 by the sub tank temperature detection circuit 44, and acquires the ink temperature in the sub tank at that time. The obtained ink temperature in the sub tank 2 is transferred to the control unit 11, and based on the value, the control unit 11 determines the PWM control value of the sub tank heater 5 by the sub tank heater PWM control circuit 41, and turns on / off the sub tank heater. The OFF control circuit 42 outputs a signal to drive the sub tank heater 5 by the PWM control determined by the sub tank heater drive circuit 43. Accordingly, the sub tank heater 5 is driven to heat the ink in the sub tank 2. The ink temperature in the sub-tank 2 obtained from the sub-tank temperature detection sensor 10 is acquired at predetermined intervals, and based on this, the control unit 11 varies the PWM control value of the sub-tank heater 5 so that the ink temperature becomes an appropriate temperature. To control.

  The predetermined interval is a predetermined time. This time is a time that is not more than the target upper limit temperature even if heating is performed based on the capacity of the sub-tank 2, and the target is adjusted even if it is left without being heated. This time is equal to or higher than the temperature, and this time is stored in the RAM 13 and is read and written as necessary. The ink supply circuit 18 drives an actuator of an ink supply system 28 described later, and supplies ink from the main tank 29 to the sub tank 2.

  The inkjet head control circuit 21 determines the ejection operation of the head by the ejection control circuit 39 based on the output from the control unit 11, transfers the print data to the inkjet head 19, and the inkjet head 19 based on the transferred print data. Ink is discharged from the ink. By the control performed, the control of the transport of the recording medium 9 by the recording medium transport roller 23 driven by the recording medium transport motor 20, and the control of the reciprocating motion along the rail 8 of the carriage 24 by the carriage drive motor 22 9 is printed. The output from the head temperature detection sensor 38 is received by the head temperature detection circuit 48, and the ink temperature in the head at that time is acquired. The obtained ink temperature in the inkjet head 19 is transferred to the control unit 11, and the control unit 11 determines the PWM control value of the head heater 37 by the head heater PWM control circuit 45 based on the value, and the head heater The ON / OFF control circuit 46 outputs a signal to drive the head heater 37 with the PWM control determined by the head heater drive circuit 47. Therefore, the head heater 37 is driven to heat the ink in the inkjet head 19. The ink temperature in the ink jet head obtained from the head temperature detection sensor 10 is acquired at predetermined intervals, and based on this, the control unit 11 varies the PWM control value of the head heater 37 so that the ink temperature immediately before ejection is appropriate. Control to be at temperature.

  The carriage encoder 30 detects the memory of the linear scale 31 and outputs a pulse train in accordance with the amount of movement of the carriage 24 that moves along the rail 8. The inkjet head control circuit 21 can detect the movement amount and the current position of the carriage 24 by counting the number of pulses transmitted from the carriage encoder 30. The control unit 11 and the inkjet head control circuit 21 perform ejection control of the inkjet head 19 based on the current position. Further, the inkjet head control circuit 21 transfers the pulse signal transmitted from the carriage encoder 30 to the control unit 11, and the control unit 11 counts the number of pulses transmitted from the inkjet head control circuit 21, and the motor control circuit The output signal to 16 is determined and the reciprocating motion of the carriage 24 along the rail 8 is controlled. The linear scale 31 is extended in the moving range of the carriage 24.

  FIG. 2 is a schematic diagram of the ink jet printer according to the present embodiment. In the inkjet printer 1, an inkjet head 19 is mounted on a carriage 24. One inkjet head 19 is provided for each color, and here, eight inkjet heads 19 for eight colors are mounted on the carriage 24. In addition, one sub tank 2 is mounted on the carriage 24 for each inkjet head 19. The carriage 24 reciprocates along the rail 8. Ink is ejected by an inkjet head 19 that reciprocates on the recording medium 9 to form a desired image. The ink in the main tank 29 is connected to the sub tank 2 via the ink supply tube 32. The ink supply tube 32 is routed from the main tank 29 to the carriage 24 through the inside of the apparatus and the cable bear 25. An ink supply motor 33 is disposed in the middle of the ink supply tube 32. The high viscosity ink in the main tank 29 is supplied to the sub tank 2 using the ink supply tube 32 and the ink supply motor 33, and is temporarily stored. Then, the ink is ejected onto the recording medium 9 from the inkjet head 19 based on the output signal from the control unit 11. The maintenance device 17 performs maintenance of the inkjet head 19. The maintenance device 17 has a cap, and when not in use, the ink-jet head 19 is capped to suck the ink in order to prevent the ink from drying or to block the ink.

  FIG. 3 shows an ink jet printer according to the present invention, in which only one color is shown among a plurality of ink supply paths.

  The ink supply system 28 includes a main tank 29, an ink supply tube 32, an ink supply motor 33, a sub tank 2, a liquid amount sensor 26, a sub tank heater 5, a sub tank temperature detection sensor 10, an air tube 34, a pressure adjustment motor 35, and an air buffer 36. , A pressure sensor 27, an inkjet head 19, a head heater 37, and a head temperature detection sensor 38.

  The ink supply motor 33 pressure-feeds high-viscosity ink from the main tank 29 to the sub tank 2 via the ink supply tube 32, and detects the amount of liquid in the sub tank provided in the sub tank 2 by the liquid amount sensor 26. Continue to supply high-viscosity ink until full is detected. Further, the ink amount in the sub tank 2 is decreased by counting the ink discharge amount by the discharge liquid amount counting circuit 40 of the ink jet head control circuit 21, and after a certain amount of ink is consumed, the ink is supplied by the ink supply motor 33. The sub tank 2 is filled.

  The pressure adjustment motor 35 drives the pump and adjusts the air pressure in the sub tank 2 via the air buffer 36 and the air tube 34 so that the pressure in the sub tank 2 which can be read by the pressure sensor 27 becomes an appropriate value. The air buffer 36 is a buffer provided to alleviate a sudden change in pressure.

  The subtank heater 5 is turned on / off by the subtank control circuit 6 based on the detection result of the subtank temperature detection sensor, thereby changing the ink temperature in the subtank 2 so that the viscosity of the high-viscosity ink becomes appropriate in printing. Adjust to temperature.

  The head heater 37 is controlled by the above-described inkjet head control circuit 21 in order to maintain the optimum discharge state of the ink temperature controlled by the sub tank heater 5 by the head temperature detection sensor 38.

  FIG. 4 is a flowchart of sub-tank ink temperature control in this embodiment. 2 shows a control flow of ink temperature of a sub tank in the present embodiment.

  The sub tank 2 is filled with a predetermined amount of ink, and it is necessary to heat the ink so that the ink has a viscosity suitable for the ink jet head 19. Therefore, first, when the user turns on the apparatus, the process is started (S1), and the ink amount in the sub tank 2 is detected by the liquid amount sensor 26 (S2). Then, it is determined whether or not the ink amount is full (S3). If the ink amount is not full, the process proceeds to step S4, where a control signal is transmitted to the ink supply circuit 18 and ink is supplied until the sub tank 2 is full (S4). If the ink is already full in step S3, the process proceeds to the next step S5 as it is.

  Next, the ink temperature in the sub tank 2 is detected by the sub tank temperature detection sensor 10 (S5). Then, it is determined whether the ink temperature is 45 ° C. or higher (S6). If the ink temperature is not 45 ° C. or higher, a control signal is transmitted to the sub tank control circuit 6, and the sub tank heater 5 is turned on so that the ink temperature becomes 45 ° C. or higher (S7). If printing is in progress, the printing is temporarily stopped (S10). Then, the process ends. If the ink temperature has already reached 45 ° C. in step S6, the process proceeds to the next step S8 as it is, and the sub tank heater 5 is turned off (S8). If the printing is in progress, the printing is continued. If the printing is temporarily stopped, the printing is enabled (S9). Then, the process ends.

  By performing this control at predetermined intervals, the ink temperature in the sub tank 2 is set to a predetermined temperature, for example, 45 ° C. This process is started when the ink jet printer is started to be used, such as when the power of the ink jet printer is turned on, or when the ink jet printer is reset.

  The RAM 13 is provided with a flag in the printable state and the temporary stop state depending on the ink temperature in the sub tank 2 and is read and written as necessary. If this flag is ON, printing is possible, and if it is OFF, printing is temporarily stopped. With this flag, control is performed so that printing can be performed when the flag is ON, and printing is not performed when the flag is OFF.

  It is determined in advance based on the heat insulation performance of the sub tank 2 and the ink capacity. In this embodiment, the target temperature range is 44.5 ° C. to 46 ° C., the target temperature is 45 ° C., and the temperature of the ink to be detected is 45 ° C. If the ink is heated too much, the viscosity of the ink decreases and proper ejection cannot be performed. If the temperature of the ink is too low, the viscosity increases and proper ejection cannot be performed. The temperature of the ink is detected at predetermined intervals, and control is performed so that the ink temperature falls within the target temperature range. The detection temperature of the sub tank temperature detection sensor 10 is set to 45 ° C., and processing is performed at predetermined intervals. With the heat insulating material arranged along the outer periphery of the sub tank 2, the speed of the ink temperature rise when the sub tank heater 5 is turned on is faster than the speed of the ink temperature drop when the sub tank heater 5 is turned off. The high temperature side is set high.

  FIG. 5 is a flowchart of ink temperature control before the printing start of the inkjet head in the present embodiment. When printing, it is necessary to set the temperature of the ink in the sub tank 2 to a predetermined temperature. The ink jet head 19 is provided with a head heater 37 and can heat the ink to a temperature optimum for ejection. However, when the temperature of the ink flowing into the inkjet head 19 is low, there are cases where the ink cannot be brought to an appropriate temperature with the capability of the head heater 37. Then, it will wait for the ink to reach an appropriate temperature. That is, continuous printing cannot be performed. In order to perform continuous printing, the ink temperature in the ink jet head 19 must be set to an appropriate temperature by the head heater 37 without being limited by the amount of ink flowing into the ink jet head 19. Therefore, the ink in the sub tank 2 is heated in advance to a temperature close to an appropriate temperature for the ink flowing into the inkjet head 19. Preferably, the temperature of the ink in the sub tank 2 is a target temperature of the ink in the inkjet head 19.

  Before starting printing, it is confirmed that there is a predetermined amount or more of ink in the sub tank 2, the ink is above the predetermined temperature, and the ink in the inkjet head 19 is above the predetermined temperature. After that, printing starts.

  First, when a print start signal is given, control is started (S11). The sub tank heater 5 and the head heater 37 are controlled so that the temperature of both the ink in the sub tank 2 and the ink jet head 19 is 45 ° C. or more (S12). Thereafter, printing is started (S13). Next, this control ends (S14).

  FIG. 6 is a control flowchart of the head heater according to this embodiment. The head heater 37 disposed in the inkjet head 19 heats the ink to an optimum temperature for ejection. That is, the viscosity is made optimal for ejecting ink.

  First, when printing is started, the head temperature control process is started (S20). Next, the temperature inside the ink jet head 19 is detected by the head temperature detection sensor 38 (S21). Then, it is determined whether the head internal temperature is 45 ° C. or higher (S22).

  If the head internal temperature is not 45 ° C. or higher, a control signal is transmitted to the inkjet head control circuit 21, and the head heater 37 is turned on so that the head internal temperature becomes 45 ° C. (S23). Next, it is determined whether the head internal temperature is 40 ° C. or less (S24). If the head internal temperature is not 40 ° C. or lower, the process proceeds to step S27. If the head internal temperature has not reached 40 ° C. in step S24, the process proceeds to stop printing (S25). In step S25, printing is temporarily stopped. Specifically, a flag indicating whether or not the ink temperature in the head in the RAM 13 has reached an appropriate temperature is set to ON which has the meaning of temporarily stopping printing. When this flag is ON, printing is not performed, and when it is OFF, printing is controlled. Then, the process ends (S28).

  If the head temperature is already 45 ° C. or higher in step S22, the process proceeds to head heater OFF (S26), and the head heater 37 is turned OFF. Then, the process proceeds to step S27.

  In step S27, the printable state is flagged. Specifically, a flag indicating whether or not the ink temperature in the head in the RAM 13 has reached an appropriate temperature is set to OFF, which means that printing is possible. When this flag is ON, printing is not performed, and when it is OFF, printing is controlled. Then, the process ends (S28).

  By performing this control process at predetermined intervals, the ink ink temperature in the inkjet head 19 is set to a predetermined temperature, for example, 45 ° C. This predetermined interval is a predetermined time, and this time is a time that is not more than the target upper limit temperature even when heating is performed based on the ink capacity of the inkjet head 19, and is left without being heated. Is the time that is equal to or higher than the target temperature, and this time is stored in the RAM 13 and is read and written as necessary.

  FIG. 7 is a control flowchart for detecting the amount of liquid in the sub tank. When a predetermined amount of ink is consumed during printing, ink is supplied to the sub tank 2.

  First, at the time when printing is started, the liquid amount detection control process is started (S29). Next, the ink consumption count is started in the discharge liquid amount counting circuit 40 of the inkjet head control circuit 21 (S30).

  Then, it is determined whether or not the ink usage amount count is equal to or greater than a certain amount (S31). When the ink is consumed above a certain amount, a control signal is output to the ink supply circuit 18 and ink is supplied to the sub tank 2. (S32). Then, the process proceeds to step S33.

  If it is determined in step S31 that the amount of ink used is less than the predetermined amount, the sub tank liquid amount detection control process is terminated (S33).

  When printing is being performed, the sub tank 2 needs to contain a predetermined amount or more of ink. This control process is executed for each consumed ink count.

  In the ink jet printer of this embodiment, a flag for determining whether printing is possible based on the ink temperature in the sub tank 2 and a flag for determining whether printing is possible based on the ink temperature in the ink jet head 19 are performed. However, when both can print, the control means performs control to enable printing. If at least one of the flags cannot be printed, the control means performs control to stop printing.

  FIG. 8 is a schematic view of the sub tank heater of the present embodiment. The sub tank heater 5 includes a heater unit 7 including a heater wire 3, a filler 51, and a shield pipe 52, a sub tank temperature detection sensor 10, a heat radiating sheet metal 53, a connector 54, and a harness 55. First, the heater wire 3 is passed through the shield pipe 52, and the shield pipe 52 and the heater wire 3 are thermally connected by the filler 51 having high thermal conductivity. Thereafter, it is sandwiched between the sub tank temperature detection sensor 10 and the heat radiating sheet metal 53 and fixed with bolts and nuts. Since the sub tank temperature detection sensor 10 is thermally connected to the heat radiating metal plate 53, a filler 51 may be enclosed. As the high thermal conductivity filler 51, a paste-like resin containing aluminum such as aluminum nitride powder can be used.

  Further, the heater wire 3 and the harness 55 are connected by a connector 54, and the harness 55 is connected to the output side of the sub tank heater drive circuit 43 and driven. Since the surface area in contact with the ink is increased by the heat dissipating metal plate 53, the heat from the heater wire 3 can be efficiently transmitted to the ink in the sub tank 2. When heated in a narrow range, only a part of the ink is heated, but can be heated in a wide range by the heat radiating sheet metal 53, and the temperature difference depending on the location can be suppressed.

  Thus, the heater which heats the ink in the sub tank 2 using the heater wire 3 with the heat radiating sheet metal 53 as the heat radiating means is configured.

  FIG. 9 is an installation view of the sub tank heater. The example which installs the sub tank heater 5 in the sub tank 2 is shown. The sub tank 2 is connected to the ink supply tube 32, and the ink flows into and out of the sub tank 2 through the ink supply tube. The liquid amount sensor 26 detects the amount of ink in the sub tank 2. The air tube 34 is a gas inflow and outflow path for adjusting the pressure in the sub tank 2. The sub tank 2 is provided with an opening for inserting the sub tank heater 5. The sub tank 2 has two sub tank heater insertion ports 56 into which the sub tank heater 5 is inserted. The number of sub-tank heaters 5 used can be determined to a desired number depending on factors such as the heat capacity of the heater, the heat capacity of the ink, and the heating time. When the subtank heater 5 is inserted into the subtank heater insertion port 56 of the subtank 2, a shielded O-ring 57 is provided around the insertion port to ensure a shielding property for preventing ink leakage. After the sub tank heater 5 is inserted, it is fixed with bolts. With respect to the insertion port that is not used, the lid 50 is prepared, the O-ring 57 is sandwiched, and secured with a bolt to ensure confidentiality. The sub tank 2 is disposed so as to cover the whole with a layer having a low thermal conductivity such as a bubbled resin layer, and insulates the inside and the outside of the sub tank 2. Heat insulation makes it difficult for the heat heated by the sub tank heater 5 to escape. Preferably, when the subtank heater 5 is inserted into the subtank 2, the harness 55, the connection terminal 54, and the exposed portion of the heat radiating sheet metal 53 are exposed to the outside so that heat does not escape from the periphery of the subtank heater 5. The heat insulating material is arranged to reduce the heat radiated from the heat radiating sheet metal 53.

  FIG. 10 is a schematic view showing another form of the sub tank heater. FIG. 2 is a structural diagram of an IH heater type sub tank heater. The ink supply tube 32 is a path for inflow and outflow of ink in the sub tank 2. The liquid amount sensor 26 detects the amount of ink in the sub tank 2. The air tube 34 is a gas inflow and outflow path for adjusting the pressure in the sub tank 2. The sub tank 2 is assembled with the heating conductor 59 inserted in the sub tank 2, and the induction coil 58 is provided outside the sub tank 2. The sub tank temperature detection sensor 10 is installed on the heating conductor 59, and controls the ink temperature in the sub tank 2 from the output signal. As a result, the surface where the heating conductor 59 disposed in the sub tank 2 is in contact with the ink can be widened, so that the ink can be heated efficiently.

  FIG. 11 is a configuration diagram between the sub tank 2 and the ink jet head 19 when the deaeration unit is mounted.

  A deaeration module 64 is disposed between the sub tank 2 and the inkjet head 19. The deaeration knit 64 includes a deaeration module 60, an air tube 34, a vacuum pump 61, a vacuum pump controller 62, and a vacuum pump control line 63. The vacuum pump controller 62 is controlled by the control unit 11.

  The deaeration unit 64 controls the vacuum pump 61 through the vacuum pump control line 63 so that the vacuum pump controller 62 reduces the pressure to a predetermined pressure. The vacuum pump 61 discharges air in the deaeration module 60 connected by the air tube 34. The deaeration module 60 allows the liquid to pass through a tube made of a gas-permeable membrane called a hollow fiber, and the space outside the tube is decompressed by the vacuum pump 61, so that the liquid in the deaeration module 60 is removed. The gas contained in is discharged.

  The ink heated in the sub-tank 2 passes through the ink supply tube 32, discharges the gas dissolved in the ink by the deaeration module 60, and is caused by bubbles generated by the presence of dissolved gas in the ink jet pressure chamber. It is possible to prevent ink ejection defects that occur. In addition, since the deaeration rate of the deaeration module 60 changes depending on the temperature of the liquid passing through the inside, the ink deaeration rate in the deaeration module 60 is kept constant by keeping the ink temperature at a predetermined temperature or higher by the sub tank heater 5. It is possible to make adjustments to keep the above.

  Although the viscosity changes depending on the temperature of the ink, the allowable amount of dissolved gas and the generation rate of bubbles also change. The amount of dissolved gas in the ink is reduced in order to suppress the generation of bubbles that cause ejection failure. This prevents ejection failure and improves the quality of the printed image. In the ink jet printer configured as described above, even if the ink jet printer has the sub tank heater 5 that heats the ink in the sub tank 2, the ink can be ejected more stably and the print quality can be improved.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Sub tank 3 Heater line 4 Pressure adjustment motor drive circuit 5 Sub tank heater 6 Sub tank control circuit 7 Heater part 8 Rail 9 Recording medium 10 Sub tank temperature detection sensor 11 Control part 12 Interface 13 RAM
14 ROM
15 transport motor encoder 16 motor control circuit 17 maintenance device 18 ink supply circuit 19 ink jet head 20 recording medium transport motor 21 ink jet head control circuit 22 carriage drive motor 23 recording medium transport roller 24 carriage 25 cable bear 26 liquid amount sensor 27 pressure sensor 28 Ink supply system 29 Main tank 30 Carriage encoder 31 Linear scale 32 Ink supply tube 33 Ink supply motor 34 Air tube 35 Pressure adjustment motor 36 Air buffer 37 Head heater 38 Head temperature detection sensor 39 Discharge control circuit 40 Discharged liquid amount count circuit 41 Sub tank Heater PWM control circuit 42 Sub tank heater ON / OFF control circuit 43 Sub tank heater drive circuit 44 Sub tank temperature detection circuit 45 Head Heater PWM control circuit 46 Head heater ON / OFF control circuit 47 Head heater drive circuit 48 Head temperature detection circuit 49 Liquid amount sensor detection circuit 50 Lid 51 Filler 52 Shield pipe 53 Heat radiating sheet metal 54 Connector 55 Harness 56 Sub tank heater insertion port 57 O-ring 58 Induction coil 59 Heating conductor 60 Deaeration module 61 Vacuum pump 62 Vacuum pump controller 63 Vacuum pump control line 64 Deaeration unit

Claims (7)

A sub-tank that is supplied with the ink from a main tank that stores ink whose viscosity decreases with increasing temperature, and temporarily stores the ink;
An inkjet head that receives the supply of the ink from the sub tank and discharges the ink;
An ink supply path connecting the sub-tank and the inkjet head;
A heat dissipating means disposed in the sub tank and in contact with the ink;
Heating means for heating the heat dissipation means;
A temperature detection sensor for measuring the temperature of the ink in the sub tank;
Control means for controlling the heating means based on the temperature detected by the temperature detection sensor to maintain the ink in a predetermined temperature range;
In an inkjet printer having
The sub-tank has an opening for inserting the heat dissipation means,
The heating means includes a U-shaped shield pipe, a heater wire passed through the shield pipe, and a heat conductive filler filled in a gap between the shield pipe and the heater wire. Including a pair of heat radiating metal plates in which the U-shaped concave portions for arranging the shield pipes are formed, and the shield pipes are arranged in the concave portions of the pair of heat radiating metal plates, The temperature detection sensor is disposed at a position sandwiched between two straight portions of the U-shaped concave portion, and the shield pipe and the temperature detection sensor are disposed in the gap to thermally connect the heat radiating metal plate. A heat conductive filler is arranged, and a connector for connecting the heater wire and a harness for connecting the heater wire to the control means is arranged at two openings at the end of the shield pipe.
The heat dissipating means has a fixing portion bent so that a portion corresponding to the opening covers the opening, is detachable from the sub tank, and the heat dissipating means is inserted and fixed to the sub tank In addition, in order to prevent leakage of the ink from the sub-tank, an O-ring disposed around the opening is sandwiched between the fixing portion and the opening of the sub-tank to seal the ink. Printer.   The inkjet printer according to claim 1, wherein the outer peripheral portion of the sub tank includes a heat insulating material at least partially. The inkjet printer according to claim 2 , wherein the heat insulating material is disposed in an exposed portion of the fixed portion with the outside . The sub tank according claim 1, wherein varying the heating capacity in accordance with the number of the heat dissipating means of the heating means is disposed within said has a plurality of openings, inserted into each of the openings Item 4. The inkjet printer according to any one of Items 3 to 4 .   The inkjet printer according to any one of claims 1 to 4, wherein the fixing portion is fixed to the sub tank by a bolt.   The carriage having the sub tank and the inkjet head mounted thereon and reciprocatingly moving in the width direction of the recording medium, and supplying the ink within the predetermined temperature range in the sub tank to the inkjet head. The inkjet printer according to any one of claims 1 to 4.   The inkjet printer according to claim 1, wherein the ink supply path includes a deaeration module that degass the ink supplied to the inkjet head.

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