JP2021030453A - Ink receiving device, image formation device, and heating control method - Google Patents

Abstract

To provide an ink receiving device capable of suitably discharging a waste ink discharged from a nozzle to an ink storage part, and to provide an image formation device and a heating control method.SOLUTION: An ink receiving device receives a waste ink discharged from a nozzle and discharges the ink to an ink storage part. The ink receiving device includes: a receiving part which receives the waste ink; a heating part which heats the waste ink received by the receiving part; and a control part which controls the heating part so as to heat the waste ink at a first temperature in a first time period and heat the waste ink at a second temperature higher than the first temperature in a second time period.SELECTED DRAWING: Figure 4

Description

The present invention relates to an ink receiving device, an image forming device, and a heating control method.

Conventionally, there is an inkjet image forming apparatus that forms an image on a recording medium by ejecting ink from a plurality of nozzles provided in an image forming head on a recording medium conveyed by the conveying device.

In such an inkjet image forming apparatus, clogging may occur in the nozzle due to an increase in the viscosity of the ink due to drying and contamination of foreign matter in the nozzle. Therefore, in the inkjet image forming apparatus, a purge process of ejecting ink from the nozzle is executed in order to replace the ink in the nozzle at the time of maintenance. The ink (waste ink) discharged from the nozzle by the purge process is received in the waste tub. After that, the waste ink in the waste tub is discharged to the waste ink tank (ink storage unit).

In addition, Patent Document 1 discloses a technique for reliably preventing leakage of waste ink and making it easy to reuse the container when the waste ink collection container is formed into a cartridge shape. Has been done.

JP-A-2007-015285

By the way, when gel-like (or hardened) ink at room temperature is received in a waste tub and discharged to a waste ink tank, the waste ink is always heated in the waste tub and discharged unless the waste ink has fluidity. It is not possible. This is because the waste ink received in the waste tub quickly becomes a gel when naturally cooled and solidifies in the waste tub. However, when the waste ink is heated by heating the waste tub, it is difficult to uniformly heat the entire waste tub.

For example, when a wall is provided at the upper end of the waste tub to prevent waste ink from leaking from the waste tub, the amount of heat radiated is large near the upper end (hereinafter referred to as the end), and the heat is generated at the center of the waste tub. Compared with this, the temperature of the waste ink is lowered. When the waste ink inside the waste tub is heated in such a state, the ink existing near the center portion has fluidity and is discharged to the waste ink tank, while the waste ink existing near the end portion becomes gel-like. Hard to be discharged into the waste ink tank. Furthermore, if the amount of heating for the entire waste tub is simply increased so that the waste ink existing near the edges is sufficiently discharged, the amount of heating for the waste ink existing near the center becomes too large (overheating). , Smoke may be generated from the waste ink.

An object of the present invention is to provide an ink receiving device, an image forming device, and a heating control method capable of preferably discharging waste ink discharged from a nozzle to an ink containing portion.

The ink receiving device according to the present invention
An ink receiving device that receives waste ink discharged from a nozzle and discharges it to an ink storage unit.
The receiving part that receives the waste ink and
A heating unit that heats the waste ink received by the receiving unit,
A control unit that controls the heating unit so as to heat at the first temperature in the first period and to heat at a second temperature higher than the first temperature in the second period.
To be equipped.

The image forming apparatus according to the present invention includes the above-mentioned ink receiving apparatus.

The heating control method according to the present invention
This is a heating control method in an ink receiving device that receives waste ink discharged from a nozzle and discharges it to an ink storage unit.
In the first period, the waste ink is heated at the first temperature, and in the second period, the waste ink is heated at a second temperature higher than the first temperature.

According to the present invention, the waste ink ejected from the nozzle can be suitably ejected to the ink accommodating portion.

It is a figure which shows the schematic structure of the inkjet image forming apparatus. It is a schematic diagram which shows the structure of a head unit. It is a block diagram which shows the main functional structure of an inkjet image forming apparatus. It is a schematic diagram which shows the structure of a waste tub. It is a graph which shows the time change of the temperature of waste ink. It is a flowchart which shows the example of a heating control process.

Hereinafter, the present embodiment will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an inkjet image forming apparatus 1. The inkjet image forming apparatus 1 includes a feeding unit 10, an image forming unit 20, a paper ejection unit 30, and a control unit 40 (see FIG. 3).

The inkjet image forming apparatus 1 (functioning as the "image forming apparatus" of the present invention) conveys the recording medium P stored in the paper feeding unit 10 to the image forming unit 20 under the control of the control unit 40, and conveys the recording medium P to the image forming unit 20. An image is formed on the recording medium P at No. 20, and the recording medium P on which the image is formed is conveyed to the paper ejection unit 30. As the recording medium P, in addition to paper such as plain paper and coated paper, various media such as cloth or sheet-shaped resin capable of fixing the ink landed on the surface can be used.

The paper feed unit 10 includes a paper feed tray 11 for storing the recording medium P, and a medium supply unit 12 for transporting and supplying the recording medium P from the paper feed tray 11 to the image forming unit 20. The medium supply unit 12 includes a ring-shaped belt whose inside is supported by two rollers, and the recording medium P is transferred from the paper feed tray 11 by rotating the rollers with the recording medium P placed on the belt. It is conveyed to the image forming unit 20.

The image forming unit 20 includes a transport unit 21, a delivery unit 22, a heating unit 23, a head unit 24, a fixing unit 25, a delivery unit 28, and the like.

The transport unit 21 holds the recording medium P mounted on the transport surface 211a (mounting surface) of the cylindrical transport drum 211, and the transport drum 211 extends in the X direction (the direction perpendicular to the paper surface in FIG. 1). By rotating around the rotating shaft (cylindrical shaft) and moving around, the recording medium P on the transport drum 211 is transported in the transport direction (Y direction). The transport drum 211 includes a claw portion and an intake portion (not shown) for holding the recording medium P on the transport surface 211a. The recording medium P is held on the transport surface 211a by pressing the end portion by the claw portion and attracting the recording medium P to the transport surface 211a by the intake portion. The transport unit 21 is connected to a transport drum motor (not shown) for rotating the transport drum 211. The transfer drum 211 rotates by an angle proportional to the amount of rotation of the transfer drum motor.

The delivery unit 22 delivers the recording medium P conveyed by the medium supply unit 12 of the paper feed unit 10 to the transfer unit 21. The delivery unit 22 is provided at a position between the medium supply unit 12 and the transfer unit 21 of the paper feed unit 10, and one end of the recording medium P conveyed from the medium supply unit 12 is held by the swing arm unit 221 and picked up. , Delivered to the transport unit 21 via the delivery drum 222.

The heating unit 23 is provided between the arrangement position of the transfer drum 222 and the arrangement position of the head unit 24, and the recording medium P conveyed by the transfer unit 21 has a temperature within a predetermined temperature range. Heat P. The heating unit 23 has, for example, an infrared heater or the like, and energizes the infrared heater based on a control signal supplied from the control unit 40 (see FIG. 3) to generate heat of the infrared heater.

The head unit 24 connects the recording medium P to the recording medium P from a nozzle opening provided on the ink ejection surface facing the transport surface 211a of the transport drum 211 at an appropriate timing according to the rotation of the transport drum 211 holding the recording medium P. On the other hand, ink is ejected to form an image. The head unit 24 is arranged so that the ink ejection surface and the transport surface 211a are separated by a predetermined distance. In the inkjet image forming apparatus 1 according to the present embodiment, four head units 24 corresponding to four colors of inks of yellow (Y), magenta (M), cyan (C), and black (K) are used on the recording medium P. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors from the upstream side in the transport direction.

FIG. 2 is a schematic view showing the configuration of the head unit 24. Here, the surface of the head unit 24 facing the transport surface 211a of the transport drum 211 is shown.

The head unit 24 includes four image forming heads 242 attached to the attachment member 244. Each of the image forming heads 242 is provided with a plurality of image forming elements (recording elements) having a pressure chamber for storing ink, a piezoelectric element provided on the wall surface of the pressure chamber, and a nozzle 243. When a drive signal for deforming the piezoelectric element is input to this image forming element, the pressure chamber is deformed due to the deformation of the piezoelectric element, the pressure in the pressure chamber changes, and ink is ejected from a nozzle communicating with the pressure chamber. ..

In the image forming head 242, two nozzle rows consisting of nozzles 243 arranged at equal intervals in a direction intersecting the transport direction of the recording medium P (in the present embodiment, a direction orthogonal to the transport direction, that is, the X direction) are arranged. It is formed. These two nozzle rows are provided so that the arrangement positions of the nozzles 243 are displaced from each other in the X direction by half of the arrangement interval of the nozzles 243 in each nozzle row.

The four image forming heads 242 are arranged in a houndstooth pattern so that the arrangement ranges of the nozzle rows in the X direction are seamlessly connected. The arrangement range of the nozzle 243 included in the head unit 24 in the X direction covers the width of the recording medium P conveyed by the transfer unit 21 in the X direction of the region where the image is formed, and the head unit 24. The position is fixed and used with respect to the rotation axis of the transport drum 211 when the image is formed. That is, the head unit 24 has a line head capable of ejecting ink over the image forming width in the X direction with respect to the recording medium P, and the inkjet image forming apparatus 1 is a single-pass type inkjet image forming apparatus. Is.

The number of nozzle rows included in the image forming head 242 may be one or three or more instead of two. Further, the number of image forming heads 242 included in the head unit 24 may be three or less or five or more instead of four.

As the ink ejected from the nozzle of the image forming element, an ink having a property of changing its phase into a gel or sol depending on the temperature and being cured by irradiating with energy rays such as ultraviolet rays is used. Further, in the present embodiment, an ink that is gel-like at room temperature and becomes sol-like when heated is used. The head unit 24 includes an ink heating unit (not shown) that heats the ink stored in the head unit 24. The ink heating unit operates under the control of the control unit 40 and heats the ink to a sol-like temperature.

The image forming head 242 ejects the heated and sol-like ink. When this sol-like ink is ejected onto the recording medium P, the ink droplets land on the recording medium P and then are naturally cooled so that the ink quickly becomes a gel and solidifies on the recording medium P.

The fixing unit 25 has a light emitting unit arranged over the width of the transport unit 21 in the X direction, and irradiates the recording medium P mounted on the transport unit 21 with energy rays such as ultraviolet rays from the light emitting unit. Then, the ink ejected on the recording medium P is cured and fixed. The light emitting portion of the fixing portion 25 is arranged to face the transport surface 211a from the arrangement position of the head unit 24 to the arrangement position of the delivery drum 281 of the delivery unit 28 in the transfer direction.

The delivery unit 28 has a cylindrical transfer drum 281 that transfers the recording medium P from the transfer unit 21 to the belt loop 282, and a belt loop 282 having a ring-shaped belt whose inside is supported by two rollers. The recording medium P delivered from the transfer unit 21 onto the belt loop 282 by the transfer drum 281 is conveyed by the belt loop 282 and sent to the paper ejection unit 30.

The paper ejection unit 30 has a plate-shaped paper ejection tray 31 on which the recording medium P sent out from the image forming unit 20 by the delivery unit 28 is placed.

FIG. 3 is a block diagram showing a main functional configuration of the inkjet image forming apparatus 1. The inkjet image forming apparatus 1 includes a heating unit 23, a head driving unit 241 and an image forming head 242, a fixing unit 25, a control unit 40, a transport driving unit 51, an operation display unit 52, an input / output interface 53, and the like. To be equipped.

The head drive unit 241 supplies image data from the nozzle 243 of the image forming head 242 by supplying a drive signal for deforming the piezoelectric element according to the image data at an appropriate timing to the image forming element of the image forming head 242. The amount of ink corresponding to the pixel value of is ejected.

The control unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a storage unit 44.

The CPU 41 reads out various control programs and setting data stored in the ROM 43, stores them in the RAM 42, executes the programs, and performs various arithmetic processes. In addition, the CPU 41 controls the overall operation of the inkjet image forming apparatus 1.

The RAM 42 provides the CPU 41 with a working memory space and stores temporary data. The RAM 42 may include a non-volatile memory.

The ROM 43 stores various control programs, setting data, and the like executed by the CPU 41. Instead of the ROM 43, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The storage unit 44 stores a print job (image formation command) input from the external device 2 via the input / output interface 53, image data related to the print job, and the like. Among them, the print job includes information related to the type of the recording medium P forming the image (for example, the size and thickness of the recording medium P) in addition to the information specifying the image data related to the image to be formed. As the storage unit 44, for example, an HDD (Hard Disk Drive) may be used, or a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

The transfer drive unit 51 supplies a drive signal to the transfer drum motor of the transfer drum 211 based on the control signal supplied from the control unit 40 to rotate the transfer drum 211 at a predetermined speed and timing.

Further, the transport drive unit 51 supplies a drive signal to the motor for operating the medium supply unit 12, the delivery unit 22, and the delivery unit 28 based on the control signal supplied from the control unit 40, and supplies the drive signal to the recording medium P. Supply to the transport unit 21 and discharge from the transport unit 21.

The operation display unit 52 includes a display device such as a liquid crystal display or an organic EL display, and an input device such as an operation key and a touch panel arranged on the screen of the display device. The operation display unit 52 displays various information on the display device, converts the user's input operation to the input device into an operation signal, and outputs the operation signal to the control unit 40.

The input / output interface 53 mediates the transmission and reception of data between the external device 2 and the control unit 40. The input / output interface 53 is composed of, for example, various serial interfaces, various parallel interfaces, or a combination thereof.

The external device 2 is, for example, a personal computer, and supplies print jobs, image data, and the like to the control unit 40 via the input / output interface 53.

In the above-mentioned inkjet image forming apparatus 1, clogging may occur in the nozzle 243 due to an increase in the viscosity of the ink due to drying, a foreign substance mixed in the nozzle 243, and the like. Therefore, in the inkjet image forming apparatus 1, at the time of maintenance, a purge process of forcibly ejecting ink from the nozzle 243 is executed in order to replace the ink in the nozzle 243. The ink (waste ink) ejected from the nozzle 243 by the purge process is received by the waste tub 60 (functioning as the "ink receiving device" of the present invention). After that, the waste ink in the waste tub 60 is discharged to the waste ink tank 63 (functioning as the “ink container” of the present invention). The waste ink tank 63 from which the waste ink has been discharged is collected by a user (for example, a serviceman).

In the present embodiment, the waste ink tank 63 includes a known waste ink amount detecting unit 64 (see FIG. 3) that detects the amount of waste ink discharged from the discharging unit 67 of the waste tub 60. The waste ink amount detection unit 64 detects the waste ink amount by detecting, for example, the liquid level height of the waste ink stored in the waste ink tank 63, and sends a detection signal indicating the detected waste ink amount to the control unit 40. Output.

By the way, when the gel-like (or hardened) ink at room temperature is received by the waste tub 60 and discharged to the waste ink tank 63, the waste ink is not always heated in the waste tub 60 to make the waste ink fluid. And cannot be discharged. This is because the waste ink received in the waste tub 60 quickly becomes a gel when naturally cooled and solidifies in the waste tub 60. However, when the waste ink is heated by heating the waste tub 60, it is difficult to uniformly heat the entire waste tub 60.

For example, when a wall is provided at the upper end of the waste tub 60 in order to prevent waste ink from leaking from the waste tub 60, the amount of heat radiated is large in the vicinity of the upper end (hereinafter referred to as the end), and the waste tub 60 has a large amount of heat. The temperature of the waste ink is lower than that in the central part. When the waste ink inside the waste tub 60 is heated in such a state, the ink existing near the center portion has fluidity and is discharged to the waste ink tank, while the waste ink existing near the end portion becomes a gel. It is hard to be discharged to the waste ink tank. Furthermore, if the heating amount for the entire waste tub 60 is simply increased so that the waste ink existing near the end portion is sufficiently discharged, the heating amount of the waste ink existing near the central portion becomes too large (overheating). ), Smoke may be generated from the waste ink.

Therefore, in the present embodiment, in order to preferably discharge the waste ink discharged from the nozzle 243 to the waste ink tank 63, the control unit 40 heats a large amount of the waste ink existing in the vicinity of the central portion of the waste tub 60. Control is performed to heat the waste ink in the waste tub 60 so that the waste ink existing near the end of the waste tub 60 also transfers from the gel state to the sol shape while preventing the waste ink from becoming too much.

FIG. 4 is a diagram showing the configuration of the waste tub 60. As shown in FIG. 4, the waste tub 60 includes a receiving portion 65 that receives the waste ink ejected from the nozzle 243, and heating portions 61A, 61B, 61C, 61D that heat the waste ink received by the receiving portion 65. The temperature detection units 62A, 62B, 62C, 62D that detect the temperature of the waste ink received by the receiving unit 65, and the wall portion erected at the upper end of the receiving unit 65 (side surface portions 65A, 65B, 65C, 65D). It is provided with 66A, 66B, 66C, 66D and a discharge unit 67 (discharge port) for discharging waste ink toward the waste ink tank 63.

The receiving portion 65 has an inverted quadrangular pyramid shape in which the ends of the four triangular side surface portions 65A, 65B, 65C, and 65D are connected to each other. The wall portions 66A, 66B, 66C, and 66D are provided to prevent waste ink from leaking from the receiving portion 65.

The heating portions 61A, 61B, 61C, 61D are provided on the back side of the side surface portions 65A, 65B, 65C, 65D (the side opposite to the front side that receives the waste ink discharged from the nozzle 243), and heat the entire back side. In the present embodiment, the heating units 61A, 61B, 61C, and 61D have a rubber heater, and the rubber heater is energized based on a control signal supplied from the control unit 40 to generate heat. As a result, the waste ink received by the receiving portion 65 is heated via the side surface portions 65A, 65B, 65C, 65D heated by the heating portions 61A, 61B, 61C, 61D.

The temperature detection units 62A, 62B, 62C, 62D are, for example, thermistors provided near the central portion on the back side of the side surface portions 65A, 65B, 65C, 65D, and indirectly measure the temperature of the waste ink received by the receiving portion 65. To detect. The temperature detection units 62A, 62B, 62C, and 62D output a detection signal indicating the temperature of the detected waste ink to the control unit 40. Based on the detection results of the temperature detection units 62A, 62B, 62C, 62D, the control unit 40 heats the heating units 61A, 61B, 61C, 61D so that the temperature of the waste ink received by the receiving unit 65 becomes a desired temperature. To control.

FIG. 5 is a graph showing the time change of the temperature of the waste ink with a solid line L when the waste ink forcibly discharged into the waste tub 60 is controlled to be heated during maintenance.

As shown in FIG. 5, the control unit 40 controls the heating units 61A, 61B, 61C, and 61D so as to start heating the waste ink at time t1 and end heating the waste ink at time t8. Specifically, the control unit 40 heats at the first temperature T1 in the first period t11 (between hours t4 and t5), and in the second period t10 (between hours t2 and t3), t12 (time). (Between t6 and t7), it is heated at a second temperature T2, which is higher than the first temperature T1.

The first temperature T1 is the portion of the side surface portions 65A, 65B, 65C, 65D where the heating temperature by the heating portions 61A, 61B, 61C, 61D is highest and is likely to be heated (specifically, the central portion, the "center portion" of the present invention. It is a temperature (for example, 85 ° C.) required for the waste ink existing in the "first portion") to shift to a state having fluidity (specifically, a sol state).

The second temperature T2 is the portion of the side surface portions 65A, 65B, 65C, 65D where the heating temperature by the heating portions 61A, 61B, 61C, 61D is the lowest and is difficult to be heated (specifically, the end portion, the "end portion" of the present invention. It is a temperature (for example, 95 ° C.) required for the waste ink existing in the "second part") to shift to a state having fluidity (specifically, a sol state).

In the second period t10, t12, the waste ink existing in the central portion where the heating temperature by the heating portions 61A, 61B, 61C, 61D is the highest among the side surface portions 65A, 65B, 65C, 65D and is easily heated is the second temperature. This is the time during which smoke is not generated from the waste ink even if it is continuously heated by T2. That is, even if heating is performed at a second temperature T2 higher than the first temperature T1 in the second period t10, t12, the side surface portions 65A, 65B, as long as the heating time does not exceed the second period t10, t12, Of the 65C and 65D, the waste ink existing in the central portion, which is most easily heated by the heating portions 61A, 61B, 61C and 61D, does not generate smoke. Here, the second temperature T2 and the second periods t10 and t12 are in an inversely proportional relationship. That is, the higher the second temperature T2, the shorter the second periods t10 and t12.

If the waste ink in the waste tub 60 is controlled to be heated only at the second temperature T2, the heating temperature by the heating units 61A, 61B, 61C, 61D is highest and exists in the central portion where heating is likely to occur. The temperature of the waste ink greatly exceeds the first temperature T1. However, in the present embodiment, in order to appropriately switch the control temperature of the waste ink between the first temperature T1 and the second temperature T2, the heating amount of the waste ink existing in the vicinity of the central portion of the waste tub 60 is increased. The waste ink in the waste tub 60 can be heated so that the waste ink existing near the end of the waste tub 60 also transfers from the gel state to the sol shape while preventing the waste ink from becoming too large. As a result, the waste ink discharged from the nozzle 243 into the waste tub 60 can be suitably discharged to the waste ink tank 63.

FIG. 6 is a flowchart showing an example of the heat control process. The process of step S101 in FIG. 6 is executed, for example, when a maintenance execution request occurs.

First, the control unit 40 controls the heating units 61A, 61B, 61C, and 61D so as to start heating the waste ink discharged from the nozzle 243 and received by the receiving unit 65 (step S101). Next, the control unit 40 refers to the detection results of the temperature detection units 62A, 62B, 62C, and 62D, and determines whether or not the temperature of the waste ink has reached the second temperature T2 within a predetermined time (step). S102).

As a result of the determination, when the temperature of the waste ink does not reach the second temperature T2 within a predetermined time (step S102, NO), the control unit 40 causes some abnormality in the heating units 61A, 61B, 61C, 61D. The operation display unit 52 is controlled so as to display a warning indicating that the abnormality has occurred (step S106). When the process of step S106 is completed, the inkjet image forming apparatus 1 ends the process in FIG.

On the other hand, when the temperature of the waste ink reaches the second temperature T2 within a predetermined time (step S102, YES), the control unit 40 receives the receiving unit 65 in the second period (t10 in the example of FIG. 5). The heating units 61A, 61B, 61C, and 61D are controlled (temperature control control) so as to heat the waste ink received in step 2 at the second temperature T2 (step S103).

Next, the control unit 40 lowers the heating temperature of the waste ink, and in the first period (t11 in the example of FIG. 5), the waste ink received by the receiving unit 65 is heated at the first temperature T1. In this way, the heating units 61A, 61B, 61C, and 61D are controlled (temperature control) (step S104).

Finally, the control unit 40 increases the heating temperature of the waste ink, and in the second period (t12 in the example of FIG. 5), the waste ink received by the receiving unit 65 is heated at the second temperature T2. In this way, the heating units 61A, 61B, 61C, and 61D are controlled (temperature control) (step S105). When the process of step S105 is completed, the inkjet image forming apparatus 1 ends the process shown in FIG. The number of times of the second period for heating the waste ink at the second temperature T2 is not limited to the two times described in the examples of FIGS. 5 and 6, but may be one time or three times or more. The point is that the waste ink existing near the end of the waste tub 60 (the part where the heating temperature by the heating parts 61A, 61B, 61C, 61D is the lowest and is difficult to heat) is also sufficiently heated to ensure that it changes from gel to sol. The number of times of the second period may be set so as to transfer.

As described in detail above, the inkjet image forming apparatus 1 according to the present embodiment has a receiving portion 65 (side surface portions 65A, 65B, 65C, 65D) for receiving the waste ink ejected from the nozzle 243 and a receiving portion 65 for receiving the waste ink. The heating units 61A, 61B, 61C, 61D for heating the waste ink, and the second temperature T1 which is higher than the first temperature T1 in the second period t10 and t12 after heating at the first temperature T1 in the first period t11. A control unit 40 that controls the heating units 61A, 61B, 61C, and 61D so as to heat at the temperature T2 of the above is provided.

According to the present embodiment configured as described above, the waste ink existing in the vicinity of the central portion of the waste tub 60 (receiving portion 65) (the portion where the heating temperature by the heating portions 61A, 61B, 61C, 61D is high and is easily heated). Waste ink existing near the end of the waste tub 60 (receiving part 65) (the part where the heating temperature by the heating parts 61A, 61B, 61C, 61D is low and it is difficult to heat) while preventing the heating amount of the ink from becoming too large. The waste ink in the waste tub 60 can be heated so that the ink changes from a gel to a sol. As a result, the waste ink discharged from the nozzle 243 into the waste tub 60 can be suitably discharged to the waste ink tank 63.

In the above embodiment, the control unit 40 may change the lengths of the second periods t10 and t12 according to the amount of waste ink in the receiving unit 65. For example, the control unit 40 may shorten the lengths of the second periods t10 and t12 as the amount of waste ink in the receiving unit 65 decreases. Furthermore, when the amount of waste ink in the receiving portion 65 is very small (in other words, when there is no waste ink near the end of the waste tub 60), the second periods t10 and t12 are provided. Instead, the lengths of the second periods t10 and t12 may be set to 0. As a result, the amount of heating by the heating units 61A, 61B, 61C, and 61D can be appropriately set according to the amount of waste ink in the receiving unit 65, and for example, it is possible to prevent the heating cost from increasing unnecessarily. Can be done.

Here, the amount of waste ink in the receiving portion 65 can be calculated by the difference between the estimated amount of waste ink ejected from the nozzle 243 during maintenance and the amount of waste ink discharged into the waste ink tank 63. .. As described above, the amount of waste ink discharged into the waste ink tank 63 is detected by the waste ink amount detecting unit 64.

Further, in the above embodiment, in the heating portions 61A, 61B, 61C, 61D, it is desirable that the power density on the end side is a predetermined multiple (for example, twice) or less of the power density on the center side. Furthermore, when the control for heating the waste ink is performed, the temperature of the waste ink existing near the end portion of the receiving portion 65 is set to be lower than the second temperature T2 in the first period t11. Is desirable. For example, considering in advance that the heating temperature by the heating portions 61A, 61B, 61C, 61D is low and difficult to heat in the vicinity of the end of the waste tub 60 (receiving portion 65), the ends of the heating portions 61A, 61B, 61C, 61D If the power density on the part side is too high, exceeding a predetermined multiple of the power density on the center side, the waste ink is placed on the end side of the waste tub 60 even though the control temperature of the waste ink is the first temperature T1. This is because the temperature of the existing waste ink exceeds the second temperature T2 (overshoot), and smoke may be generated from the waste ink.

Further, in the above-described embodiment, the example in which the recording medium P is conveyed by the conveying drum 211 has been described, but the present invention is not limited to this. For example, the recording medium P may be conveyed by a conveying belt that is supported by two rollers and moves according to the rotation of the rollers. Further, the recording medium P may be conveyed by a conveying member that reciprocates on the same plane.

Further, in the above-described embodiment, the single-pass type inkjet image forming apparatus 1 has been described as an example, but the present invention may be applied to an inkjet image forming apparatus that records an image while scanning the head unit. .. Further, the present invention may be applied to an inkjet image forming apparatus provided with a single nozzle in the head unit.

Further, in the above-described embodiments, all of them are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

1 Inkjet image forming device 2 External device 10 Paper feeding unit 11 Paper feeding tray 12 Medium feeding unit 20 Image forming unit 21 Transporting unit 211 Transporting drum 211a Transporting surface 22 Delivery unit 23 Heating unit 24 Head unit 241 Head drive unit 242 Image forming head 243 Nozzle 244 Mounting member 25 Fixing part 28 Delivery part 30 Paper ejection part 31 Paper ejection tray 40 Control unit 41 CPU
42 RAM
43 ROM
44 Storage unit 51 Transport drive unit 52 Operation display unit 53 Input / output interface 60 Waste tub 61A, 61B, 61C, 61D Heating unit 62A, 62B, 62C, 62D Temperature detection unit 63 Waste ink tank 64 Waste ink amount detection unit 65 Receiving unit 65A, 65B, 65C, 65D Side part 66A, 66B, 66C, 66D Wall part 67 Discharge part P Recording medium

Claims (10)

An ink receiving device that receives waste ink discharged from a nozzle and discharges it to an ink storage unit.
The receiving part that receives the waste ink and
A heating unit that heats the waste ink received by the receiving unit,
A control unit that controls the heating unit so as to heat at the first temperature in the first period and to heat at a second temperature higher than the first temperature in the second period.
Ink receiving device equipped with. The first temperature is a temperature at which the waste ink existing in the first portion of the receiving portion shifts to a fluid state.
The second temperature is a temperature at which the waste ink present in the second portion of the receiving portion whose heating temperature by the heating portion is lower than that of the first portion shifts to a fluid state.
The ink receiving device according to claim 1. The second period is a time during which smoke is not generated from the waste ink even if the waste ink existing in the first portion is continuously heated at the second temperature.
The ink receiving device according to claim 2. A temperature detecting unit for detecting the temperature of the waste ink received by the receiving unit is provided.
Based on the detection result of the temperature detection unit, the control unit controls the heating unit so that the temperature of the waste ink becomes the first or second temperature in the first or second period.
The ink receiving device according to any one of claims 1 to 3. The control unit changes the length of the second period according to the amount of the waste ink in the receiving unit.
The ink receiving device according to any one of claims 1 to 4. The amount of the waste ink in the receiving portion is calculated by the difference between the estimated amount of the waste ink ejected from the nozzle and the amount of the waste ink discharged from the receiving portion to the ink accommodating portion.
The ink receiving device according to claim 5. The ink accommodating unit includes a waste ink amount detecting unit that detects the amount of the waste ink discharged from the receiving unit.
The ink receiving device according to claim 6. In the heating portion, the power density on the end side is not more than a predetermined multiple of the power density on the center side.
The ink receiving device according to any one of claims 1 to 7. An image forming apparatus including the ink receiving device according to any one of claims 1 to 8. This is a heating control method in an ink receiving device that receives waste ink discharged from a nozzle and discharges it to an ink storage unit.
In the first period, the waste ink is heated at the first temperature, and in the second period, the waste ink is heated at a second temperature higher than the first temperature.
Heating control method.

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