JP5222685B2 - Inkjet image forming apparatus - Google Patents

Description

  The present invention relates to an ink jet image forming apparatus, and more particularly to an image forming apparatus capable of shortening a printing start time at a low temperature while suppressing generation of mist.

  2. Description of the Related Art Inkjet printers that form images by ejecting ink from a print head onto printing paper are widely used. A print head of an ink jet printer ejects ink by applying a driving voltage to an ink ejection mechanism such as a piezoelectric element. Ink used in an ink jet printer generally has a characteristic that viscosity increases in a low temperature environment, and it becomes difficult to ensure an appropriate discharge amount with a normal driving voltage. For this reason, at a low temperature, the ink is heated by a heater so that printing is not performed until the ink reaches an appropriate temperature. For this reason, there is a problem that the printing start time is delayed in a low temperature environment. In particular, this problem becomes more prominent in an ink circulation type printer having an ink circulation path because the amount of ink to be heated is large.

In addition to the delay in printing start time due to an increase in ink viscosity in a low-temperature environment, an inkjet printer prints mist, which is unnecessary fine ink droplets generated during ink ejection, as described in Patent Document 1. There is a problem that the print quality is deteriorated by adhering to the paper or the printer casing.
JP 2007-296754 A

  In order to advance the printing start time in a low temperature environment, it is conceivable to increase the drive voltage applied to the ink ejection mechanism to ensure an appropriate ink ejection amount. However, when the drive voltage is increased, the ink ejection speed increases and the amount of mist generated increases. As the amount of mist generated increases, the amount of mist adhering to the printer housing also increases, causing a problem that the accumulated mist stains the printing paper and the print quality deteriorates.

  SUMMARY An advantage of some aspects of the invention is that, in an inkjet image forming apparatus, the amount of mist generated is suppressed and the printing start time at a low temperature is shortened.

In order to solve the above problems, an image forming apparatus of the present invention controls a print operation based on a received print job, and measures a print job that is an elapsed time from the start of the print operation, and a drive signal. An ink ejection means having a number of nozzles for ejecting ink based on the above, an ink ejection driving means for outputting the drive signal based on the print job, and an ink temperature measurement means for measuring the ink temperature, When the ink temperature measurement value of the ink temperature measurement means is equal to or higher than the first reference temperature, which is the lower limit value of the appropriate ink temperature , the ink discharge drive means outputs the drive signal of the first voltage value, and the ink ink temperature measured value of the temperature measuring means, a second reference temperature suitable ink ejection amount by increasing the voltage of the low drive signal than the first reference temperature is a temperature which can not be secured If it is less than the first reference temperature or higher, the ink discharge driving means, said driving signal of the second voltage value larger than the first voltage value and outputs the print job control means, after the printing operation starts, housing The printing operation is interrupted when a predetermined time, which is a printing time until the amount of mist accumulated in the body reaches an allowable value, has elapsed.

  In the present invention, by outputting a drive signal having a voltage value larger than normal at a low temperature of the ink, an appropriate ink discharge amount can be secured, so that the printing start time at a low temperature can be advanced. At this time, the influence of the increase in the amount of mist generation is reduced by limiting the printing time to a predetermined time. For this reason, in the present invention, it is possible to shorten the printing start time at a low temperature while suppressing the generation amount of mist.

  At this time, after interrupting the printing operation, the print job control unit resumes the printing operation when the ink temperature measurement value of the ink temperature measuring unit becomes equal to or higher than the first reference temperature. Thereby, the interrupted printing operation can be completed. At this time, the ink discharge drive means outputs the drive signal having the first voltage value.

  In addition, since the ink storage means is included in the path, and the ink supply path further includes an ink circulation path for supplying ink to the ink discharge means and returning the ink that has not been discharged to the ink storage means, the amount of ink is large. The present invention can be effectively applied.

  At this time, an ink heating means for heating the ink is provided in the ink circulation path, and the ink heating means heats the ink when the ink temperature measurement value of the ink temperature measurement means is less than a first reference temperature, It is desirable to stop heating when the ink temperature measurement value is equal to or higher than the first reference temperature.

  When receiving an instruction from the user not to perform printing below the first reference temperature, the ink temperature measurement value of the ink temperature measuring means is equal to or higher than the second reference temperature lower than the first reference temperature, and the first reference Even when the temperature is lower than the temperature, the ink ejection driving unit and the transport control unit do not perform the above operation, and the ink ejection unit does not perform the ink ejection.

  Further, it is preferable to further include display means for displaying that the printing operation is interrupted while the printing operation is interrupted. Thereby, it is possible to notify the user that the printing operation is interrupted.

  According to the present invention, in the ink jet type image forming apparatus, it is possible to shorten the printing start time at a low temperature while suppressing the generation amount of mist.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an outline of an inkjet printer 100 according to the present embodiment. In this figure, the printing paper conveyance path is shown in the center. As shown in the drawing, the ink jet printer 100 is a paper feed mechanism for supplying printing paper, and includes a side paper feed stand 320 exposed to the outside of the side of the housing and a plurality of paper feed trays (inside the housing). 330a, 330b, 330c, 330d). Further, a paper discharge port 340 is provided as a paper discharge mechanism for discharging printed printing paper.

  The inkjet printer 100 is an inkjet line color printer. An inkjet line color printer has a plurality of inkjet heads that extend in a direction perpendicular to the paper transport direction and has a large number of nozzles as a printing mechanism, and discharges black or color ink from each inkjet head. Image formation is performed in line units.

  In addition, the inkjet printer 100 includes a control unit 200 including a controller board on which a CPU, a memory, and the like are arranged, an operation panel 400 that displays a menu and receives an operation from a user, and other functional units ( (Not shown).

  The printing paper fed one by one from the paper feed mechanism of either the side paper feed tray 320 or the paper feed tray 330 is fed into a paper feed system conveyance path (black thick line in the figure) in the housing by a drive mechanism such as a roller. And is guided to the resist portion Rg. Here, the registration unit Rg is provided to perform alignment and skew correction of the leading edge of the printing paper, and includes a pair of registration rollers 350. The fed printing paper is temporarily stopped at the registration unit Rg and conveyed toward the printing mechanism at a predetermined timing.

  A plurality of inkjet heads 130 are provided further on the conveyance direction side of the resist portion Rg. In this embodiment, it is assumed that four lines are arranged in the order of K (black), C (cyan), M (magenta), and Y (yellow) in order from the resist portion Rg. The printing paper is image-formed in units of lines by the ink ejected from each inkjet head 130 while being conveyed at a speed determined by printing conditions by an annular conveyance belt 360 provided on the opposite surface of the inkjet head 130. A suction fan 370 is provided inside the transport belt 360. A large number of air holes are formed on the surface of the conveyance belt 360, and the printing paper is adsorbed to the conveyance belt 360 and conveyed by the suction force generated by the rotation of the suction fan 370.

  The printed printing paper is further conveyed in the housing by a driving mechanism such as a roller. In the case of single-sided printing in which printing is performed only on one side of the printing paper, the paper is directly guided to the paper discharge port 340 and discharged, and the print surface is lowered to a paper discharge tray 345 provided as a receiving tray for the paper discharge port 340. It will be loaded. The paper discharge table 345 has a tray shape protruding from the casing, and has a certain thickness. The discharge tray 345 is inclined, and the printing paper that is discharged from the discharge outlet 340 and slides down along the inclination by the wall formed at a lower position of the inclination is naturally arranged and overlapped. ing.

  In the case of double-sided printing in which printing is performed on both sides of the printing paper, the front side (the first printed side is “front side” and the next printed side is “back side”) is not guided to the paper discharge port 340 at the end of printing. In addition, it is transported in the housing. For this reason, the ink jet printer 100 includes a switching mechanism 380 for switching the conveyance path for backside printing. The printing paper that has not been led to the paper discharge port 340 by the switching mechanism 380 is drawn into the switchback path SR, and is switched back, so that the front and back are reversed with respect to the transport path. Then, it is guided again to the registration portion Rg by a driving mechanism such as a roller and temporarily stops. Thereafter, the sheet is conveyed in the direction of the printing mechanism at a predetermined timing, and the back side is printed by the same procedure as that for the front side. The printing paper on which the back side is printed and images are formed on both sides is guided to the paper discharge port 340 and discharged, and is stacked on a paper discharge table 345 provided as a receiving base for the paper discharge port 340. .

  In the ink jet printer 100, switchback at the time of double-sided printing is performed using a space provided in the paper discharge tray 345. The space provided in the paper discharge tray 345 is configured to be covered so that printing paper cannot be taken out from the outside during switchback. As a result, it is possible to prevent the user from accidentally pulling out the printing paper during the switchback operation. Further, the paper discharge table 345 is originally provided in the ink jet printer 100. By performing switchback using the space in the paper discharge table 345, a separate switchback is provided in the ink jet printer 100. There is no need to provide space. Therefore, an increase in the size of the housing can be prevented. Further, since the paper discharge port and the switchback path are not shared, the switchback process and the paper discharge of other sheets can be performed in parallel.

  FIG. 2 is a diagram for explaining the configuration of the ink path-related mechanism and the control unit 200 of the inkjet printer 100. As shown in the figure, the ink jet printer 100 is a color printer that performs printing using four colors of CMYK inks. Each ink is supplied from a removable ink bottle. An ink bottle 110C that supplies cyan ink, an ink bottle 110M that supplies magenta ink, an ink bottle 110Y that supplies yellow ink, and a black ink bottle. An ink bottle 110K that supplies ink is provided. In the following description, the ink bottle 110 will be used as a representative when the ink color is not particular. The same applies to other functional units.

  Ink supplied from the ink bottle 110 passes through an ink path formed by a pipe made of resin, metal, or the like, and is temporarily stored in a downstream tank provided on the downstream side of the inkjet head 130. For this reason, the inkjet printer 100 includes a downstream tank 122C for storing cyan ink, a downstream tank 122M for storing magenta ink, a downstream tank 122Y for storing yellow ink, and a downstream tank 122K for storing black ink.

  The ink stored in the downstream tank 122 is sent to an upstream tank provided on the upstream side of the inkjet head 130 by a pump. Therefore, the inkjet printer 100 includes a pump 170C, a pump 170M, a pump 170Y, a pump 170K, an upstream tank 120C, an upstream tank 120M, an upstream tank 120Y, and an upstream tank 120K. The ink sent to the upstream tank 120 is sent to the inkjet head 130 provided with a number of nozzles for ejecting ink and used for image formation.

  As described above, the inkjet printer 100 includes the inkjet head 130C that ejects cyan ink, the inkjet head 130M that ejects magenta ink, the inkjet head 130Y that ejects yellow ink, and the inkjet head 130K that ejects black ink. Is provided. In the present embodiment, it is assumed that an ink jet head that ejects ink using a piezo element is used. However, another method, for example, an ink jet head that ejects ink by generating heat bubbles by applying heat to the ink using a heating element may be used.

  The inkjet head 130 is provided with a driver 132 (132C, 132M, 132Y, 132K) that outputs a drive signal for driving the piezo element based on the ink ejection data sent from the control unit 200. Note that the ink jet printer 100 employs a circulation system that circulates ink, and ink that has not been consumed during image formation by the ink jet head 130 is returned to the downstream tank 122. Ink feedback from the upstream tank 120 to the downstream tank 122 via the inkjet head 130 uses the water head difference between the upstream tank 120 and the downstream tank 122.

  The temperature range in which the printing quality is guaranteed is determined for the ink, and it is necessary to heat the ink when the environmental temperature is low and the ink temperature is below the guaranteed temperature range. For this reason, a heater 140 is provided in the ink path. On the other hand, the driver 132 and the piezo element generate heat when operated. A cooler 160 for cooling the ink is provided in order to suppress the influence of an increase in the ink temperature at a high temperature due to the Joule heat of the heat generation and the ink vibration. The ink that has passed through the heater 140 and the cooler 160 is sent to the upstream tank 120.

  Each inkjet head 130 includes a thermometer 134 (134C, 134M, 134Y, 134K) that directly or indirectly measures the ink temperature.

  The control unit 200 is a functional unit that controls print job processing, ink temperature control, and other processing in the inkjet printer 100. In the present embodiment, the control unit 200 includes a print job control unit 210, an image processing unit 220, an ink ejection control unit 230, a conveyance control unit 240, an ink circulation control unit 250, and an ink temperature adjustment unit 260.

  The print job control unit 210 controls execution, suspension, restart, error handling, log recording, and the like of a print job received from a user. A print job received from printing can be a print process based on print data sent from a computer, a copy process based on image data read from an image reading apparatus, a facsimile print process based on image data sent through a telephone line, or the like. . When performing printing at a low ink temperature as described later, the print job control unit 210 interrupts the printing operation when a predetermined time has elapsed. Thereby, the generation amount of mist is suppressed. Therefore, the print job control unit 210 includes a print time measuring unit 211 that measures an elapsed time from the start of the printing operation. Further, the print job control unit 210 can accept a selection as to whether or not to execute early printing start at a low temperature temperature from the user.

  The image processing unit 220 performs image processing on the image data that is the target of the print job. The image processing performed by the image processing unit 220 can be, for example, print data expansion processing, image data color conversion processing, binarization processing, halftone processing, and the like. The ink ejection control unit 230 calculates the ink ejection amount for each dot based on the image data after image processing, and outputs the ink ejection amount to the driver 132 of the inkjet head 130. Here, the inkjet head 130 expresses the gradation by the number of ink drops, the highlight portion of the image is expressed by a small number of drops, and the shadow portion is expressed by a large number of drops.

  The conveyance control unit 240 controls operations of the registration roller 350, the conveyance belt 360, and other conveyance mechanisms in order to convey the printing paper. The ink circulation control unit 250 circulates ink in the ink circulation path by controlling the operation of the pump 170 and the like. The ink temperature adjustment unit 260 operates the heater 140 or the cooler 160 according to the measurement result of the thermometer 134 provided in the inkjet head 130 to control the ink temperature to be within the appropriate temperature range.

  FIG. 3 is a block diagram showing the configuration of the inkjet head 130. As shown in the drawing, the ink jet head 130 includes a thermometer 134 that measures the temperature of ink that is supplied through an ink path 135 that forms part of the ink circulation path and that flows through the ink path 135. .

  Control data indicating the number of ink drops for each pixel output from the ink ejection control unit 230 is input to the driver 132, and the driver 132 outputs a drive signal having a predetermined voltage value to the piezo element group 136 based on the control data. When the piezo element group 136 is deformed in accordance with the drive signal, ink is ejected from the nozzle group 137. Therefore, the piezo element group 136 and the nozzle group 137 function as ink ejection means. The driver 132 functions as an ink discharge driving unit, and outputs a driving signal having a voltage larger than normal to the piezo element group 136 when the ink temperature is low.

  Next, the print execution process in this embodiment will be described. In the present embodiment, the lower limit value of the appropriate ink temperature is set as the first reference temperature. The first reference temperature can be set to 25 ° C., for example. For this reason, the ink temperature adjustment unit 260 operates the heater 140 to heat the ink when the ink temperature is lower than 25 ° C. At this time, the ink circulation control unit 250 circulates the ink.

  Here, if printing is not executed until the ink temperature reaches 25 ° C. or higher, the printing start time is delayed when the ink temperature is low. In particular, since the ink jet printer 100 of the present embodiment is an ink circulation type, the amount of ink to be heated is large, and extra ink heating time is required.

  Accordingly, the second reference temperature of the ink temperature is set, and if the user desires, printing is executed if the ink temperature is equal to or higher than the second reference temperature. Here, the second reference temperature is a temperature lower than the first reference temperature, and can be set to 20 ° C., for example. However, when the ink temperature is lower than the first reference temperature, the viscosity of the ink increases and an appropriate ink discharge amount cannot be secured. Therefore, an appropriate ink discharge amount is secured by increasing the voltage value of the drive signal output to the piezo element group 136 to be larger than usual.

  However, when the drive voltage is increased, the ink ejection speed increases and the amount of mist generated increases. As the amount of mist generated increases, the amount of mist adhering to the printer housing also increases, causing a problem that the accumulated mist stains the printing paper and the print quality deteriorates. Therefore, in this embodiment, it is assumed that a print execution process as shown in the flowchart of FIG. 4 is performed. Here, for the sake of simplicity, it is not handled when the ink temperature is high and exceeds the appropriate range.

  First, if the measured value of the ink temperature is equal to or higher than the first reference temperature, for example, 25 ° C. or higher (S101: Yes), normal printing processing is executed assuming that the ink temperature is within the appropriate temperature range (S115). If ink heating has been performed, ink heating is stopped (S114). Here, when the measured value of the temperature is different for each ink color, for example, it can be determined by an average value of each ink temperature, or can be determined based on the lowest ink temperature. In the normal printing process, the driver 132 outputs a drive signal having a normal voltage value that can ensure an appropriate discharge amount within an appropriate temperature range to the piezo element group 136.

  On the other hand, if the measured value of the ink temperature is less than the first reference temperature, for example, less than 25 ° C. (S101: No), the ink temperature adjustment unit 260 operates the heater 140 to raise the ink temperature to an appropriate temperature, The ink is heated (S102).

  If the user has not instructed the early printing start at the time of low ink temperature (S103: No), it waits without printing until the measured value of the ink temperature becomes equal to or higher than the first reference temperature, and measures the ink temperature. When the value is equal to or higher than the first reference temperature (S101: Yes), ink heating is stopped (S114), and normal printing processing is executed (S115).

  Here, when the user desires to start early printing at a low temperature of the ink, for example, the user can set the early printing start with a printer driver that issues a print instruction. Alternatively, the setting for early printing start may be performed via the operation panel 400 of the inkjet printer 100. Further, a default setting may be made as to whether or not the administrator starts early printing.

  If the early printing start is instructed when the ink temperature is low (S103: Yes), it is determined whether the measured value of the ink temperature is equal to or higher than the second reference temperature, for example, 20 ° C. (S104). As a result, when the measured value of the ink temperature is lower than the second reference temperature (S104: No), the process waits until the measured value of the ink temperature becomes equal to or higher than the second reference temperature. This is because when the temperature is lower than the second reference temperature, the increase in the viscosity of the ink is large, and an appropriate ink discharge amount cannot be secured even if the voltage of the drive signal is increased. In other words, a temperature at which an appropriate ink discharge amount cannot be secured even when the voltage of the drive signal is increased is set as the second reference temperature.

  When the measured value of the ink temperature is equal to or higher than the second reference temperature (S104: Yes), the printing process is executed (S105). At this time, in order to ensure an appropriate ink discharge amount, a drive signal having a voltage value larger than usual is output to the piezo element group 136 (S105).

  FIG. 5 is a diagram illustrating an example of a drive signal output to the piezo element group 136. FIG. 5A shows a drive signal output at normal time, and FIG. 5B shows a drive signal output at low temperature. Here, for one drop, the drive signal is applied to the piezo element as one set of a negative voltage pulse for expanding the ink chamber and a positive voltage pulse for contracting the ink chamber. Therefore, this pulse set is repeatedly applied to a plurality of dropped pixels. Further, in order to stabilize the ink ejection amount, a short pulse called a pre-pulse is inserted before the first pulse set.

  In the present embodiment, when the measured value of the ink temperature is normally equal to or higher than the first reference temperature, as shown in FIG. 5A, the drive signal having the voltage value V1 is output to the piezo element, and the measured value of the ink temperature is the first value. When the temperature is lower than the second reference temperature and lower than the first reference temperature, as shown in FIG. 5B, a drive signal having a voltage value V2 larger than V1 is output to the piezo element.

  Thus, an appropriate ink discharge amount is ensured even at a low temperature of the ink. However, as the drive voltage is increased, the ink discharge speed increases and the amount of mist generated increases. In the present embodiment, in order to reduce the influence of the increase in the amount of mist generated, printing at a low temperature is limited to a predetermined time Tm. For this reason, when the printing operation is started, measurement of the printing time is started (S105).

  Here, the reason for limiting the printing time when the ink temperature is low to the predetermined time Tm is as follows. That is, mist accumulates in the printer housing due to the occurrence of mist, but even if the amount of mist generated increases by increasing the drive voltage, the amount of mist accumulated in one print job is not long. Not much. For this reason, it is considered that the printing operation within the predetermined time Tm is acceptable. Therefore, the predetermined time Tm is experimentally determined in advance, for example, in consideration of the amount of mist accumulated in one print job, the average printing rate, the amount of mist accumulated and the number of printed sheets that require maintenance in the printer housing, and the like. I can keep it.

  If the printing time has passed the predetermined time Tm during printing with a drive signal having a voltage higher than normal (S106: Yes), printing is interrupted (S107). As a result, the printing operation at a large drive voltage at which the amount of mist generated increases is stopped, so that the amount of mist generated can be suppressed within an allowable range. At this time, in order to indicate that the printing operation is interrupted, a display indicating that the printing operation is interrupted while the ink is warmed is displayed on the display screen of the operation panel 400 as shown in FIG. It is desirable to do so.

  Thereafter, the process waits until the measured value of the ink temperature becomes equal to or higher than the first reference temperature (S108: No), and when the measured value of the ink temperature becomes equal to or higher than the first reference temperature (S108: Yes), the ink heating is stopped (S109). ). Then, the printing condition is changed to the normal voltage drive signal, and the interrupted printing is resumed (S110). Since this printing operation is a drive signal having a normal voltage value, the amount of mist generated is not as great as that of a printing operation with a large drive voltage.

  Before the elapse of the predetermined time Tm (S106: No), and when the measured value of the ink temperature becomes equal to or higher than the first reference temperature (S111: Yes) during printing with a drive signal with a voltage higher than normal (S111: Yes). Then, the ink heating is stopped (S112), the printing process is changed to the printing process with the driving signal of the normal voltage value and the normal sheet interval, and the printing is continued (S113).

  As a result of performing the above printing operation, in this embodiment, as shown in FIG. 7, when the measured value of the ink temperature is equal to or lower than the second reference temperature, the heater is operated to heat the ink, and the ink temperature is set to the second reference temperature. The printing operation can be started from time t1 when the temperature is reached. Conventionally, the influence of an increase in the amount of mist generated by setting the drive signal to V2 larger than normal V1 is large, and printing could not be started until time t2 when the ink temperature becomes the first reference temperature. In the embodiment, the printing time is limited to the predetermined time Tm, thereby reducing the influence of the increase in the amount of mist generated. For this reason, in this embodiment, it is possible to shorten the printing start time at a low temperature while suppressing the amount of mist generated.

It is a figure which shows the outline | summary of the inkjet printer which concerns on this embodiment. It is a figure for demonstrating the structure of the ink path | route related mechanism of an inkjet printer, and a control part. It is a block diagram which shows the structure of an inkjet head. 6 is a flowchart illustrating print execution processing according to the present embodiment. It is a figure which shows the example of the drive signal which changed the voltage value. It is a figure which shows an example of the screen displayed during printing interruption. It is a figure which shows the relationship between ink temperature and printing start time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Inkjet printer, 110 ... Ink bottle, 120 ... Upstream tank, 122 ... Downstream tank, 130 ... Inkjet head, 132 ... Driver, 134 ... Thermometer, 135 ... Ink path, 136 ... Piezo element group, 137 ... Nozzle group, DESCRIPTION OF SYMBOLS 140 ... Heater, 160 ... Cooler, 170 ... Pump, 200 ... Control part, 210 ... Print job control part, 211 ... Print time measurement part, 220 ... Image processing part, 230 ... Ink discharge control part, 240 ... Conveyance control part , 250 ... Ink circulation control unit, 260 ... Ink temperature adjustment unit, 320 ... Side paper feed tray, 330 ... Paper feed tray, 340 ... Paper discharge port, 345 ... Paper discharge tray, 350 ... Registration roller, 360 ... Conveyor belt, 370 ... Suction fan, 380 ... Switching mechanism, 400 ... Operation panel

Claims (6)

A print job control means for controlling a print operation based on the received print job and measuring a print time which is an elapsed time from the start of the print operation;
An ink ejection means having a number of nozzles for ejecting ink based on a drive signal;
Ink ejection driving means for outputting the driving signal based on the print job;
An ink temperature measuring means for measuring the ink temperature,
When the ink temperature measurement value of the ink temperature measurement means is equal to or higher than the first reference temperature, which is the lower limit value of the appropriate temperature of ink ,
The ink discharge driving means outputs the driving signal of a first voltage value;
Ink temperature measured value of the ink temperature measuring means, a second reference temperature or less than the first reference temperature suitable ink ejection amount by increasing the voltage of the drive signal is at a temperature which can not be ensured lower than the first reference temperature In the case of
The ink discharge driving means outputs the driving signal having a second voltage value larger than the first voltage value;
The print job control unit interrupts the printing operation when a predetermined time, which is a printing time until the amount of mist accumulated in the housing reaches an allowable value after a printing operation starts , is interrupted. apparatus. The image forming apparatus according to claim 1,
The image forming apparatus, wherein after the printing operation is interrupted, the printing job control unit resumes the printing operation when an ink temperature measurement value of the ink temperature measuring unit becomes equal to or higher than a first reference temperature. The image forming apparatus according to claim 1, wherein:
An image forming apparatus comprising an ink circulation path that includes an ink storage means in the path, supplies ink to the ink discharge means, and returns ink that has not been discharged to the ink storage means. The image forming apparatus according to claim 3, wherein
An ink heating means for heating the ink in the ink circulation path;
The ink heating means heats ink when the ink temperature measurement value of the ink temperature measurement means is less than a first reference temperature, and stops heating when the ink temperature measurement value is equal to or higher than the first reference temperature. An image forming apparatus. The image forming apparatus according to claim 1,
When receiving an instruction from the user not to perform printing below the first reference temperature, the ink temperature measurement value of the ink temperature measuring means is equal to or higher than the second reference temperature lower than the first reference temperature, and the first reference The image forming apparatus, wherein even if the temperature is lower than the temperature, the print job control unit does not execute a printing operation. The image forming apparatus according to claim 1,
An image forming apparatus, further comprising a display unit for displaying that the printing operation is interrupted during the interruption of the printing operation.