JP5485735B2 - Inkjet printer and control method - Google Patents

Description

  The present invention relates to an ink jet printer and a control method capable of detecting the state of an ink supply path.

  In an inkjet printer, ink stored in an ink tank is supplied into an inkjet head by suction or pressurization using a pump, and the ink is ejected onto a medium to form an image.

  However, for example, deterioration / damage due to the passage of time from the ink tank to the ink jet head and the ink chamber in the ink jet head, drying / thickening / precipitation of ink in the supply path or ink chamber, and problems with the ink supply pump Other factors may cause problems in the ink supply to the inkjet head.

  In contrast, as shown in Patent Documents 1 and 2, for example, when ink is supplied, negative pressure on the ink in the inkjet head, the flow rate of ink in the supply path, the amount of liquid discharged from the inkjet head, and the change in the weight of the ink tank It has been proposed to determine whether ink supply is normally performed by measuring other physical quantities.

JP 2006-231131 A JP 2008-238638 A

  However, in the conventional determination method, it is necessary to add a pressure sensor, a flow sensor, a weight sensor, an actuator, or other expensive members to the ink jet printer in order to measure the physical quantity described above, and the structure of the ink jet printer is complicated. At the same time, it led to an increase in costs.

  Some conventional inkjet printers control the temperature of ink in the inkjet head to be within a predetermined temperature range. This is because ink characteristics such as viscosity change with temperature change, so that the ink characteristics suitable for the ink jet head can be maintained. Some ink jet printers include a heater for heating the ink jet head and a temperature sensor for detecting the temperature of the ink jet head.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet printer capable of determining the state of an ink supply path to an ink jet head without adding an expensive member.

In order to solve the above problems, an inkjet printer of the present invention includes an inkjet head that forms an image by ejecting ink onto a medium, a pump that supplies ink to the inkjet head, a head heater that heats the inkjet head, and an inkjet a temperature sensor for detecting the temperature of the head, on the basis of the temperature detected by the temperature sensor, the operating state of the head heaters to maintain the temperature of the ink-jet head within a predetermined control temperature range is a temperature range from room temperature and a control unit for controlling, the pump is operated a predetermined time, the ink is supplied to the ink to the inkjet head while discharged from the ink jet head, wherein the control part, based on the detected temperature, the supply path of ink to the ink jet head In the inkjet printer to determine the status, wherein, when determining the state of the supply path, the ink jet head and controls the operating state of the head heaters to maintain within the control temperature range, the It is determined whether or not the temperature of the inkjet head is maintained within the control temperature range before determining the state of the supply path. If the temperature is not maintained within the control temperature range, the determination of the state of the supply path is performed. If it is maintained within the control temperature range, the determination of the state of the supply path is continued, and if it continues, control for maintaining the temperature of the ink jet head within the control temperature range is continued thereafter. And the pump is turned on when the temperature of the inkjet head is maintained within the control temperature range. The state of the supply path is determined based on the transition of the temperature of the inkjet head after the pump is operated for a predetermined time and the pump is operated for the predetermined time, and the determination is made such that the minimum temperature of the inkjet head is within a predetermined temperature range. Determining whether or not the supply path is abnormal when the minimum temperature is outside the predetermined range, and determining that the supply path is normal when the minimum temperature is within the predetermined range; When the state of the supply path is normal after the determination of the state of the supply path, the ink is ejected while the temperature of the inkjet head is maintained within the control temperature range to form the image on the medium. It is characterized by.

  In the ink jet printer of the present invention, the control temperature range is preferably a temperature range higher than room temperature.

  In the ink jet printer of the present invention, it is preferable to determine the state of the supply path when the image formation by the ink jet head is not performed.

  The controller of the ink jet printer according to the present invention indicates that the supply path state is abnormal when the detected temperature is within the control temperature range after a predetermined time has elapsed from the start of ink supply during ink supply to the ink jet head by the pump. It is preferable to judge.

  The control unit of the ink jet printer according to the present invention further has a detection temperature within a predetermined temperature range lower than the control temperature range after a predetermined time has elapsed from the start of ink supply during ink supply to the ink jet head by the pump. It is preferable to determine that the state of the supply path is normal, and to determine that the state of the supply path is abnormal when the detected temperature is higher than a predetermined temperature range.

  The control unit of the ink jet printer according to the present invention may also be configured so that the supply path state is determined when the amount of decrease in the detected temperature from the start of ink supply to the lapse of a predetermined time is greater than or equal to a predetermined amount during ink supply to the ink jet head by the pump. Is determined to be normal, and it is preferable to determine that the state of the supply path is abnormal when the descending amount is less than a predetermined amount.

  In the ink jet printer of the present invention, ink is supplied to the ink jet head through a supply tube, and the supply tube includes a second temperature sensor different from the temperature sensor, and a second heater for heating the supply tube, and the control unit includes Based on the temperature detected by the temperature sensor and the temperature detected by the second temperature sensor, the operation state of the head heater is controlled so as to maintain the temperature of the inkjet head within the control temperature range, and the pump is driven to When supplying ink, it is preferable to determine the state of the ink supply path to the inkjet head based on the temperature detected by the temperature sensor and the temperature detected by the second temperature sensor.

The ink jet printer of the present invention further includes a cap for sealing the ink discharge surface of the ink jet head, and the pump is operated in a state where the ink discharge surface of the ink jet head is sealed by the cap. the inner and the negative pressure, it is preferable from the nozzle surface of the inkjet head is a suction pump for supplying the ink to said ink jet head by sucking the ink.

  In the ink jet printer of the present invention, the pump is preferably a pressure pump that is disposed on the ink supply side to the ink jet head and pressurizes the ink to supply the ink jet head.

An inkjet printer control method according to the present invention includes: an inkjet head that forms an image by ejecting ink onto a medium; a pump that supplies ink to the inkjet head; a head heater that heats the inkjet head; A temperature sensor that detects the temperature, and a control that controls the temperature of the inkjet head to be within a predetermined control temperature range that is higher than room temperature by operating the head heater based on the temperature detected by the temperature sensor. And an ink tank that stores ink to be supplied to the ink jet head, operates the pump for a predetermined time, discharges the ink from the ink jet head, supplies the ink to the ink jet head, and detects the detected temperature. Based on the A control method for an inkjet printer comprising the step of determining the state of the supply path of the ink to the click-jet head, when determining the state of the supply path, to maintain the temperature of the ink-jet head in the control temperature range And determining whether or not the temperature of the inkjet head is maintained within the control temperature range before determining the state of the supply path, and if not maintained within the control temperature range, The determination of the state is not performed, and if it is maintained within the control temperature range, the determination of the state of the supply path is continued, and if this is continued, the temperature of the inkjet head is further maintained within the control temperature range. with ever the control for maintaining, in a state where the temperature of the ink jet head is maintained within the control temperature range, the Pump is injected ink into the ink-jet head of the non-driven state by driving the predetermined time, determines the state of the feed path based on the transition temperature of subsequent said ink jet head, said determination, said ink jet head It is determined whether the minimum temperature is within a predetermined temperature range. If the minimum temperature is outside the predetermined range, the supply path is abnormal. If the minimum temperature is within the predetermined range, the supply path wherein the step of determining the state of the supply path of the ink jet head, wherein the time condition of the supply path after the state of the supply path determination is normal, the ink jet condition to the normal The method includes forming the image on the medium by ejecting the ink while maintaining the temperature of the head within the control temperature range .

  According to the present invention, it is possible to provide an ink jet printer that can easily and accurately determine the state of a supply path without incurring a complicated structure and an increase in cost.

1 is a schematic diagram illustrating an internal configuration of an inkjet printer according to a first embodiment of the present invention, and is a diagram illustrating a state where an inkjet head is being scanned. FIG. 1 is a schematic diagram illustrating an internal configuration of an ink jet printer according to a first embodiment of the present invention, and is a diagram illustrating a state where ink is being supplied. FIG. It is the schematic which shows the structure of the head unit and pump unit which concern on 1st Embodiment of this invention. 1 is a block diagram illustrating a configuration of an inkjet printer according to a first embodiment of the present invention. It is a graph which shows the temperature detected by the temperature sensor which concerns on 1st Embodiment of this invention. It is a graph which shows the temperature detected by the temperature sensor which concerns on 1st Embodiment of this invention, Comprising: It is a graph which shows the temperature change example when ink is normally attracted | sucked. It is a graph which shows the temperature detected by the temperature sensor which concerns on 1st Embodiment of this invention, Comprising: It is a graph containing the example of a temperature change when the state of a supply path | route is abnormal. It is a flowchart which shows the flow of judgment of the state of the supply path | route using the temperature sensor which concerns on 1st Embodiment of this invention. It is the schematic which shows the structure of the head unit and pump unit which concern on 2nd Embodiment of this invention.

  Hereinafter, an inkjet printer according to an embodiment of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic diagram illustrating an internal configuration of the inkjet printer 100 according to the first embodiment, and is a diagram illustrating a state in which the inkjet head 122 is scanned. FIG. 2 is a schematic diagram showing the internal configuration of the ink jet printer 100, and shows a state where ink is being supplied. FIG. 3 is a schematic diagram illustrating the configuration of the head unit 120 including the inkjet head 122 and the pump unit 130 including the suction pump 132. FIG. 4 is a block diagram illustrating a configuration of the inkjet printer 100. In FIGS. 1 and 2, the illustration of the configuration other than the head unit 120, the pump unit 130, and the scanning system of the head unit 120 is omitted.

  As shown in FIGS. 1 and 2, the inkjet printer 100 according to the first embodiment includes a head unit 120 having an inkjet head 122, a head heater 124, and a temperature sensor 125, a pump unit 130 having a suction pump 132, And a control unit 140 including a control circuit that controls the head unit 120, the pump unit 130, and other components.

Below, the detailed structure of each member is demonstrated.
As shown in FIG. 3, the head heater 124 and the temperature sensor 125 are provided in the inkjet head 122. The inkjet head 122 is mounted on the carriage 121 so that the nozzle surface faces the platen 112 side. The platen 112 is fixed to the inkjet printer 100.

  The inkjet head 122 includes a plurality of heads respectively corresponding to a plurality of colors, and forms an image by ejecting ink onto the upper surface of the medium 114 conveyed by the conveyance motor 147. The medium 114 is a sheet-like or plate-like medium such as a resin sheet or paper. The inkjet head 122 is driven by a head driver 149 based on the control of the control unit 140. The head driver 149 includes a driver circuit for driving each color head of the inkjet head 122.

  The control unit 140 sends an instruction signal corresponding to the image data to the head driver 149 according to a program stored in a ROM (Read Only Memory) 141. Image data is sequentially sent from the data stored in a RAM (Random Access Memory) 142 to the buffer RAM 148 by a predetermined amount by the control unit 140, and the inkjet head 122 is driven according to the data stored in the buffer RAM 148.

  The medium 114 is transported by the transport motor 147. The transport motor 147 is driven by the motor driver 143 based on the control of the control unit 140. The medium 114 is conveyed in the image forming area formed between the platen 112 and the inkjet head 122 along the width direction of the long plate-like platen 112, that is, the direction perpendicular to the paper surface of FIGS.

  The inkjet head 122 is scanned together with the carriage 121. As shown in FIGS. 1 and 2, the carriage 121 is fixed to the driving belt 116 and moves on the rail 117 as the driving belt 116 operates. The drive belt 116 is operated by a carriage motor 146, and the carriage motor 146 is driven by a motor driver 143 based on the control of the control unit 140. The rail 117 extends in a direction orthogonal to the conveyance direction of the medium 114, whereby the carriage 121 and the inkjet head 122 are scanned in the width direction of the medium 114.

  The control unit 140 forms an image on the medium 114 by scanning the inkjet head 122 while transporting the medium 114 based on the program in the ROM 141 for the image data stored in the RAM 142.

  In the ink jet printer 100 of the first embodiment, the ink in the ink jet head 122 is heated to a constant temperature in order to stabilize the image quality. For this purpose, a head heater 124 is provided for each color head constituting the inkjet head 122. The head heater 124 generates heat by driving and heats the corresponding head, and uses, for example, a resistance element. The head heater 124 is driven by a heater drive circuit 150. The heater drive circuit 150 receives a signal obtained by modulating a command signal output from the control unit 140 according to a program stored in the ROM 141 into a predetermined pulse width by a PWM (Pulse Width Modulation) circuit 151.

  Note that a plurality of head heaters may be provided for each head of each color, and one common heater may be provided for all heads.

  The temperature of the inkjet head 122 is continuously detected by the temperature sensor 125, and the detected temperature is stored in the RAM 142. For example, a thermistor is used as the temperature sensor 125. Based on the temperature detected by the temperature sensor 125, the control unit 140 controls the operating state of the head heater 124 so as to maintain the temperature of the inkjet head 122 within the control temperature range TA shown in FIG.

  The temperature control of the inkjet head 122 by the control unit 140 will be described with reference to FIG. FIG. 5 is a graph showing the temperature detected by the temperature sensor 125.

  The control temperature range TA is a temperature range from a lower limit temperature TA1 to an upper limit temperature TA2 across the discharge temperature T0 that is the target temperature of the inkjet head 122. The ink jet printer 100 enters a temperature rising sequence in which the head heater 124 immediately heats the ink jet head 122 from the time P1 when the control unit 140 starts temperature control. This temperature increase sequence starts from a temperature TB1 which is a room temperature RT and continues until a time P2 when the temperature detected by the temperature sensor 125 is stabilized at the discharge temperature T0. The time P1 for starting the temperature control by the control unit 140 includes, for example, a time when the ink jet printer 100 is turned on.

  The control temperature range TA is set in accordance with the specifications of the inkjet printer 100, particularly the acceptable range of image quality.

  After the temperature increase sequence, the temperature of the inkjet head 122 is controlled to maintain the control temperature range TA as a standby / steady state until the time P3 when image formation is started. The control is performed by the control unit 140 turning on / off the operation of the head heater 124 according to the detection result of the temperature sensor 125 according to a program and condition values stored in advance in the ROM 141.

  Even in the image forming state after the time P3, the control unit 140 maintains the temperature of the inkjet head 122 within the control temperature range TA shown in FIG. 5 based on the temperature detected by the temperature sensor 125. The operation state of 124 is controlled.

  Next, ink supply to the inkjet head 122 will be described.

  Ink is supplied through a supply tube 123 from a plurality of ink tanks corresponding to each color head. Supply is performed by sucking ink from the nozzle surface side using the pump unit 130. One end of the supply tube 123 is connected to each color head of the inkjet head 122, and the other end is connected to an ink tank (not shown).

  The ink tank is a tank that stores ink for supplying ink. The form of the ink tank can be arbitrarily selected, and a back pressure tank for adjusting the negative pressure in the inkjet head 122 can also be included.

  The pump unit 130 includes a cap 131, a suction pump 132, and a drain tube 133, and is disposed at a home position that is located at one end of the inkjet head 122 in the scanning direction. The suction pump 132 and the drainage tube 133 are independently connected to each color head.

  The cap 131 is moved up and down by the elevating motor 145 and lifted to realize a state of airtightly covering the nozzle surface of the inkjet head 122, and moved down to be separated from the nozzle surface. The lift motor 145 is driven by a motor driver 143 in accordance with an instruction signal from the control unit 140.

  When the suction pump 132 is operated when the nozzle surface is airtightly covered with the cap 131, the suction pump 132 sucks the ink in the inkjet head 122. The sucked ink is drained through the drain tube 133. Accordingly, ink is supplied from the ink tank into the inkjet head 122 through the supply tube 123 by the suction operation of the suction pump 132. The suction pump 132 is driven by a pump motor 144 driven by a motor driver 143 in accordance with an instruction signal from the control unit 140.

  The motor driver 143 includes a motor driver circuit for driving each of the pump motor 144, the lift motor 145, the carriage motor 146, and the transport motor 147.

  In addition, the inkjet printer 100 includes a display device 152. As the display device 152, for example, a liquid crystal panel can be used. The display device 152 is controlled by the control unit 140 and displays information corresponding to the operation status in accordance with a program stored in the ROM 141 in advance.

  Further, the inkjet printer 100 includes a timer 153. The operation of the timer 153 is controlled by the control unit 140, and measures the time from the start of ink suction by the suction pump 132, for example.

  As described above, the inkjet head 122 is heated by the head heater 124 and maintained at a temperature higher than room temperature. When ink is supplied from an unheated ink tank by sucking the ink-jet head 122 with a suction pump 132, the temperature of the ink in the ink-jet head 122 and further the ink-jet head are affected by the newly supplied ink. The temperature at 122 temporarily decreases.

  However, when the ink supply to the ink jet head 122 cannot be performed normally, a large amount of ink heated inside remains, so that the amount of decrease in the temperature of the ink jet head 122 is smaller than that when the ink is normally supplied. .

  Paying attention to such a temperature change, the control unit 140 drives the suction pump 132 to supply ink into the inkjet head 122, and based on the temperature detected by the temperature sensor 125, the inkjet head The state of the ink supply path to 122 is determined.

  Here, the supply path includes a path through which ink flows when ink is supplied using the pump unit 130 in addition to a path through which ink is supplied from the ink tank to the inkjet head 122. Specifically, a supply tube 123, an inkjet head 122, a cap 131, a suction pump 132, and a drainage tube 133 are included. Therefore, the controller 140 dries / thickens / solidifies ink in these supply paths, deteriorates / damages the supply paths, and abnormalities in supply paths due to the presence or absence of poor adhesion between the cap 131 and the inkjet head 122. Can also be judged. In addition to ink, the ink includes, for example, liquid flowing in the supply path such as cleaning liquid and moisturizing liquid.

  Hereinafter, the determination of the state of the ink supply path to the inkjet head 122 using the detection result of the temperature sensor 125 will be described with reference to FIGS. Here, FIG. 6 is a graph showing the temperature detected by the temperature sensor, and is a graph showing an example of temperature change when ink is normally sucked. FIG. 7 is a graph showing the temperature detected by the temperature sensor, and includes a temperature change example when the state of the supply path is abnormal. In FIG. 7, examples when the supply path state is abnormal are indicated by broken lines L1 and L2, and an example when the supply path state is normal is indicated by broken line L3. In FIGS. 6 and 7, the control and temperature change up to time P3 are the same as those in FIG.

  In FIG. 6, ink suction by the suction pump 132 is started from time P3. When new ink that has not been heated is filled into the inkjet head 122, the temperature of the inkjet head 122 starts to decrease, and reaches the lowest temperature T11 at time P4 after the predetermined time PA has elapsed.

  Here, the time P4 is a time stored in the ROM 141 in advance. For example, it substantially corresponds to the time when the ink chamber of the inkjet head 122 is filled with new ink. Further, it may substantially correspond to the time when the channel in the inkjet head 122 is replaced with new ink. Further, it may correspond to the time for the ink in the inkjet head 122 to be replaced with the room temperature ink in the ink path. Further, the ink supply may be a predetermined amount, or the time for turning on the pump may be determined in advance. Since the optimum measurement time varies depending on the heat capacity of the inkjet head, the ink supply speed of the ink supply path, the environmental temperature, etc., values based on these conditions are determined in advance and stored in the ROM 141. The value is read out based on this and used for measurement.

  When the ink supply shown in FIG. 6 is normal, the temperature of the inkjet head 122 at time P4 decreases until it falls within the predetermined temperature range TB. The predetermined temperature range TB is a temperature range in which the temperature TB1 which is the room temperature RT is a lower limit and the temperature TB2 higher than the temperature TB1 is an upper limit.

  Here, the predetermined time PA is set in advance according to the capacity of the ink chamber in the inkjet head 122, the suction capability of the suction pump 132, and the inner diameter of the supply tube 123, and is stored in the ROM 141. The control unit 140 causes the timer 153 to measure the elapsed time from the start of ink suction by the suction pump 132, and whether the supply path state is normal or abnormal depending on the temperature of the inkjet head 122 when the elapsed time reaches the predetermined time PA. Make a decision.

  On the other hand, in the example indicated by the broken line L1 in FIG. 7, the temperature T21 at the time P4 is within the control temperature range TA, and the temperature drop T2 is smaller than the drop T1 when the ink supply indicated by the broken line L3 is normal. . In the example indicated by the broken line L2, the temperature T31 at the time P4 is lower than the control temperature range TA, but does not reach the upper limit of the predetermined temperature range TB. Further, the temperature drop amount T3 in this example is also smaller than the drop amount T1 when the ink supply is normal.

  As shown in the example shown in FIG. 6 and the example shown by the broken line L3 in FIG. 7, the controller 140 is in a normal state of the supply path when the temperature T11 after the predetermined time PA elapses is within the predetermined temperature range TB. Judge that there is.

  The determination of the state of the supply path can also be performed using the temperature drop amount T1. As a predetermined amount of the temperature drop that is a criterion for determination in this case, for example, it is preferable to use a difference between the discharge temperature T0 and the upper limit temperature TB2 of the predetermined temperature range TB.

  On the other hand, when the temperature T21 after the predetermined time PA has elapsed within the control temperature range TA as in the example shown by the broken line L1 in FIG. When the temperature T31 after the time PA has elapsed is lower than the control temperature range TA but higher than the predetermined temperature range TB, the control unit 140 determines that the state of the supply path is abnormal and displays That is displayed on the device 152.

  Next, with reference to FIG. 8, a flow for determining whether the state of the supply path is normal or abnormal will be described. FIG. 8 is a flowchart showing the flow of determination of the state of the supply path using the temperature sensor 125.

  In step S1, temperature control of the inkjet head 122 is started. In the example shown in FIG. 8, it is assumed that the temperature raising sequence has already been completed and a standby / steady state has been reached.

  Subsequently, as step S2, the control unit 140 determines whether or not the temperature detected by the temperature sensor 125 is normal. That is, it is determined whether or not the detected temperature is within the control temperature range TA. When the detected temperature is not within the control temperature range TA or when the temperature is not detected, it is determined that there is an abnormality in the temperature control, that is, No in step S2. When the temperature control is abnormal, the control unit 140 displays on the display device 152 that the head temperature control is an error, and ends the temperature control.

  On the other hand, when the detected temperature is within the control temperature range TA, it is determined that the temperature control is normal, that is, Yes in step S2, and the temperature control is continued as step S3. Subsequently, the suction operation by the suction pump 132 is performed according to the state of the ink jet printer 100 or according to an instruction from the user. As an instruction from the user, for example, an instruction to perform a sequence including a suction operation such as a cleaning operation can be given.

  When the operation of the suction pump 132 is started as step S4 and suction is performed for a predetermined time as step S5, the control unit 140 causes the temperature sensor 125 to move the inkjet head 122 after the predetermined time PA has elapsed from the start of suction as step S6. Let the temperature be detected. Note that the predetermined time during which suction is performed in step S5 is stored in the ROM 141 in advance.

  The control unit 140 that has received the detected temperature after the elapse of the predetermined time PA from the temperature sensor 125 determines whether or not the detected temperature is lower than the temperature TA1 that is the lower limit value of the head control temperature in step S7.

  If the detected temperature is the same as or higher than the temperature TA1, that is, if No in step S7, the control unit 140 displays on the display device 152 that there is an error in ink suction as step S11. Then, the determination of whether the supply path state is normal or abnormal ends.

  On the other hand, when the detected temperature indicates a temperature lower than the temperature TA1, that is, when Yes in step S7, as step S8, the control unit 140 determines the predetermined temperature range TB at the time of pump suction with a normal detected temperature. It is determined whether it is in.

  If the detected temperature is not within the predetermined temperature range TB, that is, No in step S8, as step S12, the control unit 140 displays on the display device 152 that there is an error in ink suction, and The determination of whether the state is normal or abnormal ends.

  On the other hand, if the detected temperature is within the predetermined temperature range TB, that is, if YES in step S8, in step S9, the control unit 140 determines that the ink supply is normal, and whether the supply path state is normal. End the determination of whether there is an abnormality.

  When the supply path state is normal, image formation can be continued or resumed thereafter. However, when the supply path state is abnormal, the temperature shown in FIG. 8 is displayed after the sequence for returning the supply state to normal. Control again.

  In the inkjet printer 100 of the first embodiment, a second heater that heats the supply tube 123 and a second temperature sensor that detects the temperature of the supply tube 123 may be provided. The second temperature sensor is preferably arranged around the second heater, similarly to the arrangement of the temperature sensor 125 with respect to the head heater 124. In this configuration, the control unit 140 first sets the operation state of the head heater so as to maintain the temperature of the inkjet head 122 within the control temperature range based on the temperature detected by the temperature sensor 125 and the temperature detected by the second temperature sensor. Control. Further, when the controller 140 drives the pump 132 to supply ink to the inkjet head 122, the control unit 140 supplies ink to the inkjet head 122 based on the temperature detected by the temperature sensor 125 and the temperature detected by the second temperature sensor. The state of the supply path is determined. As a result, the temperature of the supply tube 123 can be controlled, and the state of the supply path can be determined with high accuracy.

  Furthermore, the temperature sensor for determining the state of the supply path does not have to be attached to heat the ink in the inkjet head 122 like the temperature sensor 125 of the first embodiment. For example, the ink jet head 122 may be provided newly or additionally. In addition, although it is preferable to measure the temperature of the ink, a temperature that replaces the temperature of the ink may be measured instead. For example, the temperature of the ink jet head 122 and / or the temperature of the supply tube 123 and other ink flow paths may be measured. Or the temperature of the carriage 121 may be measured.

  Further, the determination of the state of the supply path can be performed at a time other than when an image is formed on the medium. That is, it can be performed not only when the ink is supplied to the inkjet head 122 using the suction pump 132 but also when the suction pump 132 is not operated.

  As another form, a series of steps for determining the state of the supply path can be performed when the inkjet head 122 is in a non-driving state, for example, a state in which a driving pulse is not applied to the inkjet head 122. As a result, the influence of driving the ink jet head can be removed, so that more accurate measurement and determination can be performed.

With the configuration described above, the following effects are achieved according to the above embodiment.
(1) Since the state of the supply path can be determined, image formation can be performed with the ink jet head 122 appropriately filled with ink. Therefore, the quality of the image to be formed can always be maintained constant. In addition, since image formation failures due to ink supply abnormality are reduced, ink and media are less wasted.
(2) Since the state of the supply path can be determined using a temperature sensor provided in an ink jet printer that controls the temperature by heating the ink jet head, there is no need to add an expensive member as in the conventional case. For this reason, the cost concerning an inkjet printer can be held down. Furthermore, since no new member is added, the structure is not complicated and the design of the structure is not restricted.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a schematic diagram illustrating the configuration of the head unit 220 and the pressure pump 232 according to the second embodiment. In the second embodiment, a pressure pump 232 is used instead of the suction pump 132 of the first embodiment.

  Similar to the head unit 120 of the first embodiment, the head unit 220 of the second embodiment includes an inkjet head 222, a head heater 224, and a temperature sensor 225. Since the inkjet head 222, the head heater 224, and the temperature sensor 225 have the same configuration as the inkjet head 122, the head heater 124, and the temperature sensor 125 of the first embodiment, descriptions thereof are omitted.

  The pressure pump 232 is provided in the middle of a supply tube 223 between an ink tank (not shown) and the inkjet head 222, and supplies the ink that has been sucked from the ink tank to supply the ink to the inkjet head 222 side. To do. The pressure pump 232 is driven by a pump motor 144 driven by a motor driver 143 in accordance with an instruction signal from the control unit 140.

  Further, below the nozzle surface of the ink jet head 222, a drain liquid receiver 235 is disposed to receive the discharged ink pushed out from the nozzle surface of the ink jet head 222 by driving the pressure pump 232. During image formation, the pressurized pressure is released to the pressure pump and / or the supply path around the pressure pump so that the ink supply path from the ink tank to the inkjet head 222 does not hinder communication. It is preferable to provide a pressure release mechanism.

When the pressure pump 232 is used, a simpler configuration can be obtained.
Other configurations, operations, and effects are the same as those in the first embodiment.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or changed within the scope of the purpose of the improvement or the idea of the present invention.

  As described above, the ink jet printer according to the present invention is useful for an ink jet printer that requires confirmation of the state of a supply path, and is particularly suitable for an ink jet printer that includes a heater in an ink jet head.

DESCRIPTION OF SYMBOLS 100 Inkjet printer 120 Head unit 121 Carriage 122 Inkjet head 123 Supply tube 124 Head heater 125 Temperature sensor 130 Pump unit 131 Cap 132 Suction pump 133 Drainage tube 140 Control part 150 Heater drive circuit 220 Head unit 222 Inkjet head 223 Supply tube 224 Head Heater 225 Temperature sensor 232 Pressure pump

Claims (6)

An inkjet head that forms an image by ejecting ink onto a medium;
A pump for supplying ink to the inkjet head;
A head heater for heating the inkjet head;
A temperature sensor for detecting the temperature of the inkjet head;
A control unit that controls the operating state of the head heater so as to maintain the temperature of the inkjet head within a predetermined control temperature range that is a temperature range higher than room temperature based on the temperature detected by the temperature sensor;
With
Operating the pump for a predetermined time, discharging the ink from the inkjet head and supplying the ink to the inkjet head;
In the inkjet printer that determines the state of the supply path of the ink to the inkjet head based on the detected temperature ,
The controller is
When determining the state of the supply path, control the operation state of the head heater so as to maintain the inkjet head within the control temperature range,
It is determined whether or not the temperature of the inkjet head is maintained within the control temperature range before determining the state of the supply path. If the temperature is not maintained within the control temperature range, determination of the state of the supply path is performed. If it is maintained within the control temperature range, the determination of the state of the supply path is continued, and if this is continued, the control for maintaining the temperature of the inkjet head within the control temperature range is continued thereafter. And when the temperature of the inkjet head is maintained within the control temperature range, the pump is operated for the predetermined time,
The state of the supply path is determined based on the temperature transition of the inkjet head after the pump has been operated for the predetermined time, and the determination determines whether the minimum temperature of the inkjet head is within a predetermined temperature range. When the minimum temperature is outside the predetermined range, the state of the supply path is abnormal, and when the minimum temperature is within the predetermined range, the state of the supply path is normal.
When the state of the supply path is normal after the determination of the state of the supply path, the ink is ejected while the temperature of the inkjet head is maintained within the control temperature range to form the image on the medium. An inkjet printer characterized by the above.   The inkjet printer according to claim 1, wherein the determination of the state of the supply path is performed when image formation by the inkjet head is not performed.   The controller is in an abnormal state when the detected temperature is within the control temperature range after a predetermined time has elapsed from the start of the ink supply during the ink supply to the inkjet head by the pump. The inkjet printer according to claim 1, wherein the inkjet printer is determined.   A cap for sealing the ink discharge surface of the ink-jet head; and in a state where the ink discharge surface of the ink-jet head is sealed by the cap, the pump is operated to make the inside of the cap have a negative pressure, The inkjet printer according to claim 1, wherein the inkjet printer is a suction pump that supplies the ink to the inkjet head by sucking the ink from the nozzle surface side of the inkjet head.   The inkjet printer according to claim 1, wherein the pump is a pressure pump that is disposed on an ink supply side to the inkjet head and pressurizes the ink to supply the inkjet head with the ink.   An inkjet head that forms an image by ejecting ink onto a medium, a pump that supplies ink to the inkjet head, a head heater that heats the inkjet head, a temperature sensor that detects the temperature of the inkjet head, and the temperature A control unit that operates the head heater based on a temperature detected by a sensor to control the temperature of the inkjet head to be within a predetermined control temperature range that is higher than room temperature, and ink supplied to the inkjet head An ink tank for storing the ink, operating the pump for a predetermined time, discharging the ink from the inkjet head, supplying the ink to the inkjet head, and ink to the inkjet head based on the detected temperature Supply path status A control method for an ink jet printer including a decision to process,
  When determining the state of the supply path,
  Maintaining the temperature of the inkjet head within the control temperature range;
  It is determined whether or not the temperature of the inkjet head is maintained within the control temperature range before determining the state of the supply path. If the temperature is not maintained within the control temperature range, determination of the state of the supply path is performed. If it is maintained within the control temperature range, the determination of the state of the supply path is continued, and if this is continued, the control for maintaining the temperature of the inkjet head within the control temperature range is continued thereafter. When the temperature of the inkjet head is maintained within the control temperature range, the pump is driven for the predetermined time to inject ink into the non-driven inkjet head, The state of the supply path is determined based on the temperature transition of the inkjet head, and the determination is based on the fact that the minimum temperature of the inkjet head is It is determined whether the temperature is within a constant temperature range. If the minimum temperature is outside the predetermined range, the supply path state is abnormal. If the minimum temperature is within the predetermined range, the supply path state is normal. And determining the state of the ink supply path of the inkjet head to be,
  When the state of the supply path is normal after the determination of the state of the supply path, the ink is ejected while the temperature of the inkjet head is maintained within the control temperature range to form the image on the medium. A control method for an ink jet printer, comprising: a step.

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