JP2021070320A - Liquid discharge device - Google Patents

Abstract

To enable avoidance of damage to a medium and preheating control while taking account of improvement in image quality.SOLUTION: A liquid discharge device includes: first heating means that heats a medium; and a control unit that, when the first heating means heats a medium with first output at the time of preheating and a temperature of the medium reaches a predetermined threshold, controls the first heating means to heat the medium with second output that is equal to or larger than the first output and controls transportation means to start transportation of the medium.SELECTED DRAWING: Figure 5

Description

The present invention relates to a liquid discharge device.

Conventionally, there are various devices that control preheating during printing. For example, in Patent Document 1, in an image forming apparatus that can be used as a plurality of image recording devices such as a copy, facsimile, and printer, a heating element temperature detecting means and a controlling means, a heating element preheating temperature changing means, and a predetermined time. The image formation number counting means for each of the above functions is provided, and the preheating temperature of the heating element is controlled according to the counting result. Further, there is disclosed an apparatus in which two states, a power saving state and a standby state, are provided as control means for the heating element, and the two states are switched based on the above counting result.

In Patent Document 1, the above configuration is used to quickly respond to the user's request and save labor for heat generation. However, when this configuration is adopted in a serial inkjet printing apparatus, , As shown below, preheating control is not always sufficient.

In a serial inkjet printing device, when printing on a film such as acrylic, polyester, or vinyl chloride, a non-penetrating medium such as coated paper, or a slow-penetrating medium, the ink is dried by warm air drying or IR (infrared). In order to heat the media before or during printing, the printing device is equipped with a post heater, a print heater (platen heater), and a preheater in the sub-scanning direction, and is the most suitable media depending on the location of each sub-scanning depending on the media type. The temperature sensor provided in each heater is independently temperature-controlled so as to reach the temperature.
The principle of infrared heating utilizes the fact that infrared rays are a type of electromagnetic waves and are light energy having a certain wavelength. The major difference from warm air is that light enters the coating film (the film formed on the ink surface). Basically, warm air acts only on the surface. The way the heat is transferred is heat conduction from the surface. Therefore, since drying starts from the surface layer of the coat, problems such as skinning are likely to occur, and there is a limit to rapid drying. In addition, a film (film formation) is formed on the surface of the ink, making it difficult for water and solvents to escape from the inside.

In the method of performing infrared heating with a conventional serial inkjet printing device, the cure heater having the infrared heating device is turned on at the start of printing. For this reason, for the image at the start of printing, the temperature sensor that detects the surface temperature of the media does not detect that the infrared heating device has sufficiently warmed up, and the amount of heat is insufficient and drying defects are likely to occur, which is good. There was a problem that it was difficult to obtain a good image.
On the other hand, in a serial inkjet printing apparatus, the media is usually stopped before printing. This is because it is inefficient to move the media before printing, considering the waste paper. If the above-mentioned infrared heating device is turned on while the media is stopped, heat is concentrated on one part of the media, causing problems (damage) such as media deformation and melting. Therefore, the infrared heating device was turned off until the printing operation was started and the media moved. However, as described above, in order for the infrared heating device to give a desired output to the media, the infrared heating device needs to be warmed to some extent before printing.

In the prior art, preheating control is not performed in consideration of these problems in the serial inkjet printing apparatus, that is, avoidance of damage to the media and improvement of image quality.
An object of the present invention is to provide a liquid discharge device capable of preheating control in consideration of avoiding damage to media and improving image quality.

In the liquid discharge device according to the present invention, when the first heating means for heating the medium and the first heating means heat the medium with the first output during preheating and the temperature of the medium reaches a predetermined threshold value. , A control unit that controls the first heating means so as to heat the medium with a second output that is equal to or higher than the first output, and starts the transfer of the medium by the transfer means. It is configured as a device.

According to the present invention, preheating control can be performed in consideration of avoiding damage to the media and improving image quality.

It is an external perspective view of the inkjet recording apparatus in this embodiment. It is the schematic plan view of the carriage scanning mechanism part shown in FIG. It is sectional drawing of the dry part shown in FIG. It is a block diagram which shows the structural example of the recording apparatus in this Example. It is explanatory drawing of the preheating operation performed by the recording apparatus in this Example.

Hereinafter, embodiments of the liquid discharge device will be described in detail with reference to the accompanying drawings. The liquid discharge device according to the present embodiment has the following features in, for example, a serial type inkjet recording device using an infrared heating device. That is, when the print JOB is turned on, it is controlled to enter the preheating operation of the infrared heating device before starting the printing operation. Therefore, the dry quality of the image at the start of printing can be satisfied. Further, the control related to the preheating operation is lower than that at the time of actual printing, and the output is performed at a temperature at which the recording medium is not actually damaged. Therefore, damage such as deformation and melting of the recording medium can be prevented by the preheating operation. Then, by the preheating operation controlled in this way, it is determined that the preheating is completed at the timing when the internal temperature of the infrared heating device becomes equal to or higher than a predetermined threshold value, and the printing operation is started. The features of the present invention described above will be described in detail with reference to the following drawings.

FIG. 1 is an external perspective view of the inkjet recording device 100 according to the present embodiment. Further, FIG. 2 is a schematic plan view of the carriage scanning mechanism portion shown in FIG. As shown in these figures, inside the recording device 100, a guide rod 1 and a sub guide rail 2 are hung on both side plates, and a carriage 5 is directed to the guide rod 1 and the sub guide rail 2 in the direction of arrow A. It is held movable in the (main scanning direction).
A timing belt 11 spanned by a drive pulley 7 and a pressure pulley 10 is connected to the carriage 5. When the timing belt 11 is driven by the main scanning motor 9 via the drive pulley 7, the carriage 5 is reciprocated in the main scanning direction A. Tension is applied to the timing belt 11 by the pressure pulley 10, and the carriage 5 can be driven without sagging. The “HP (home position) position” P is set, for example, on the upper part of the maintenance mechanism 26.

The print medium 150 is intermittently conveyed in the direction of arrow B (sub-scanning direction) at the lower part where the carriage 5 reciprocates, and droplets are emitted from the recording heads 6k, 6c, 6m, and 6y mounted on the carriage 5 on the platen 16. Is ejected to form a predetermined image. That is, a plurality of nozzles (not shown) are provided in the recording heads 6k to 6y, and ink is ejected from the nozzles to form an image.
In the paper ejection guide 32 (FIG. 3), the image-formed print medium 150 is dried by the drying unit 17, which is a drying heater. Further, the recording device 100 is provided with a cartridge 60 that supplies ink to the recording head 6 (FIG. 3) and a maintenance mechanism 26 that executes maintenance of the recording head 6 mounted on the carriage 5. An encoder sensor 13 is arranged in the carriage 5, and by continuously reading the encoder sheets 14 spanned on both side plates, it drives between the two side plates while detecting the position in the main scanning direction.

Further, a media detection sensor 20 is attached to the carriage 5, for example, a reflection type sensor is attached, and the reflected light emitted by the LED is detected to detect the presence or absence of an object in the lower part. In this embodiment, the platen outer area, the platen upper area, and the media upper area directly under the carriage are identified according to the value of the reflected light.

FIG. 3 is a cross-sectional view of the drying portion 17 shown in FIG. The left side of FIG. 3 is the front surface of the recording device 100 shown in FIG. The recording paper is transported from the right side in the figure to the left side transport direction D. Four heaters, a preheater 17-1, a print heater 17-2, a post heater 17-3, and an infrared heating device 17-4 are arranged on the transport path.

The preheater 17-1 is a heater that warms the recording medium. By warming the preheater 17-1 from the medium side to which it is conveyed, when the ink lands, it is easily evaporated (preheating).
The print heater 17-2 is a heater that forms a film on the ink surface (ink set) by evaporating the water content of the ink. A film is formed on the surface of the ink by forming a film, and the ink is dried to the extent that it cannot be touched by touch. It is also called an ink set because the spread and size of ink droplets (dots) are determined at this time by film formation. It is the most important heater for making images.
The post heater 17-3 is a heater that further warms the recording medium, evaporates the water and solvent of the ink, and dries the ink.
The infrared heating device 17-4 is a heater that heats the surface of the ink from the inside of the ink by far infrared rays (IR) to cause a polymerization reaction of the resin inside the ink to cure the ink.

The preheater 17-1, the print heater 17-2, and the post heater 17-3 are temperature sensors (17-1a, 17-2a, 17-3a) which are thermistors for measuring the temperature of the transport surface heated by the heater, respectively. Is provided. Heater control is performed based on the measurement results of these temperature sensors, and the temperature of the transport surface is controlled. A thermistor is used for the temperature sensor and is attached to the back side of the transport surface.
In addition, each heater is provided with a thermostat (17-1b, 17-2b, 17-3b) so that the thermostat can be turned off when each heater becomes uncontrollable and the abnormal temperature rises. .. Each heater and each thermostat are connected in series, and when the thermostat is cut off, the power supply to the heater is also cut off, ensuring safety.

The infrared heating device 17-4 includes at least one or a plurality of infrared heaters 17-4a as heat sources, a thermopile 17-4b which is a non-contact temperature sensor for measuring the surface temperature of a recording medium, and a reflector 17-4f. Thermostat 17-4c that measures the temperature inside the infrared heating device 17-4 by measuring, Thermostat 17-4d that secures safety by disconnecting during abnormal heating, Humidity near the medium by generating airflow Cure fan 17-4e, which suppresses the rise of infrared rays to promote drying, and further suppresses overheating of the infrared heating device, and infrared rays emitted from the infrared heater 17-4a are reflected to heat in the direction of the recording medium. It is provided with a reflecting plate 17-4f for promoting.
A thermopile 17-4b, which is a non-contact temperature sensor, is used for temperature control of the infrared heating device 17-4. The thermopile 17-4b measures the temperature of the surface of the recording medium, and the output of the infrared heater 17-4a is controlled so that the surface temperature of the recording medium becomes a desired temperature. The second temperature sensor, thermistor 17-4c, is installed on the reflector 17-4f and measures the temperature of the reflector 17-4f. The role of the thermistor 17-4c is to monitor whether the temperature inside the infrared heating device 17-4 has risen abnormally and to determine whether preheating is completed.

FIG. 4 is a block diagram showing a configuration example of the recording device in this embodiment. As shown in FIG. 4, the recording device 100 has a control unit 400 that performs control in this embodiment. The control unit 400 has a CPU 401, an FPGA 402, and a motor driver 403, and performs various controls performed by the recording device, such as CPU control, memory control, ink ejection control, sensor control, and motor control.
Further, as shown in FIGS. 1 and 2, the recording device 100 includes a main scanning motor 9, a carriage 5 driven by the main scanning motor 9, a recording head 6 mounted on the carriage 5, and a main scanning encoder. It has a sensor 13 and a media detection sensor 20.
Further, the recording device 100 has a sub-scanning motor 404 and a transport unit 405 driven by the sub-scanning motor 404. The transport unit 405 includes a sub-scanning encoder sensor 4051 that detects the transport amount in the sub-scanning direction, and a transport roller 4052 that transports the recording medium in the sub-scanning direction.

In addition, ordinary recording devices such as a take-up motor (not shown), a take-up unit having a take-up roller and a take-up encoder sensor, a paper feed motor, and a paper feed unit having a paper feed roller and a paper feed encoder sensor should be provided. It has various mechanisms.
The drying unit 17 includes a preheater 17-1 (M pieces: divided into M pieces in the sub-scanning direction), a print heater 17-2 (N pieces: divided into N pieces in the main scanning direction), and a post heater 17-3 (M pieces: divided into N pieces in the main scanning direction). K pieces: divided into K pieces in the main scanning direction and the sub-scanning direction), and an infrared heating device 17-4 (L pieces: divided into L pieces in the main scanning direction or L = 1). Further, a temperature sensor is arranged for measuring the temperature of each of the divided heaters of each heater. For example, the preheater 17-1 is provided with a thermistor 17-1a which is a temperature sensor, the print heater 17-2 is provided with a thermistor 17-2a which is a temperature sensor, and the post heater 17-3 is a temperature sensor. A thermistor 17-3a is provided. Further, the infrared heating device 17-4 is provided with a thermistor 17-4c which is a temperature sensor (second temperature sensor) and a thermopile 17-4b which is a non-contact type temperature sensor. The control unit 400 controls the output so that the heater reaches the target temperature based on the value of the temperature sensor.

FIG. 5 is an explanatory diagram of a preheating operation performed by the recording device in this embodiment. As shown in FIG. 5, when the control unit 400 determines that the print JOB has been turned on, each heater enters the preheating operation, and when the preheating is completed, the transfer of the recording medium is started and the printing operation is started. Since the preheater 17-1, the print heater 17-2, and the post heater 17-3 are heaters that transfer heat from the back side of the recording surface side of the recording medium by the guide plate, the temperature of each guide plate monitored by each thermistor is high. Preheating is completed when the target temperature is reached.
Since the infrared heating device 17-4 is not in direct contact with the recording medium, the surface temperature of the recording medium is measured using the thermopile 17-4b, which is a non-contact temperature sensor, and the temperature is monitored. The infrared heater 17-4a provided in the infrared heating device 17-4 has a good temperature response to the recording medium, and further, when the recording medium is stopped, the infrared heater 17-4a is a recording medium even when the infrared heater 17-4a is not sufficiently warmed. The temperature of the infrared rays rises rapidly. Therefore, if the printing operation is started even if the surface of the recording medium reaches the target temperature, the infrared heaters 17-4a are not sufficiently warmed. Therefore, when the recording medium starts to move, the infrared heater 17 The amount of heat of -4a cannot keep up, and the temperature of the recording medium cannot be maintained.

From the above, the surface temperature of the recording medium by the thermopile 17-4b alone is not sufficient as a condition for completing the preheating of the infrared heating device 17-4. Therefore, the temperature of the thermistor 17-4c, which is the second temperature sensor for monitoring the temperature of the reflector 17-4f inside the infrared heating device 17-4, was set as the condition for completing the preheating. That is, if the infrared heater 17-4a is sufficiently warm, it can be determined that the temperature of the thermistor 17-4c in the vicinity of the infrared heater 17-4a also exceeds a predetermined threshold value, so that the threshold value can be appropriately set. The preheating condition can be satisfied by setting.

Hereinafter, the preheating operation of the infrared heating device 17-4 will be described with reference to FIG. When the control unit 400 determines that the print JOB has been turned on, the control unit 400 turns on the infrared heaters 17-4a. When the infrared heater 17-4a is turned on, the temperature of the surface of the recording medium rises, and the control unit 400 raises the detection temperature 501 of the thermopile 17-4b to B ° C., which is the control temperature at the time of preheating. -4a is controlled.
When the control unit 400 determines that the thermopile 17-4b has reached B ° C., the detection temperature 502 of the thermistor 17-4c is lower than the preheating target temperature T, which is a predetermined threshold value, but gradually increases. Is. The control unit 400 continues the preheating while maintaining the thermopile 17-4b at B ° C. until the temperature of the thermistor 17-4c reaches the preheating target temperature T. Then, the control unit 400 determines that the preheating is completed at the timing t when the detection temperature 502 of the thermistor 17-4c exceeds the preheating target temperature T.

At this time, the control unit 400 has reached a predetermined threshold value at the detection temperature 502 of the thermistor 17-4c, which can determine that the preheating of the preheater 17-1, the print heater 17-2, and the post heater 17-3 has already been completed. In this case, the printing operation P is entered and the recording medium is conveyed. When entering the printing operation P, the control unit 400 controls the thermopile 17-4b so that the temperature reaches A ° C., which is the control temperature at the time of printing. The control temperature at the time of printing is equal to or higher than the control temperature at the time of preheating, and is a temperature (A ≧ B) to which a predetermined difference temperature d is added. If the control unit 400 determines that the preheating of the preheater 17-1, the print heater 17-2, and the post heater 17-3 has not been completed, the thermopile 17 is used until the preheating is completed or even after the preheating is completed. Control so that the temperature of -4b is maintained at B ° C.

The control unit 400 sets the temperature required for drying the ink on the recording medium to A ° C., which is the control temperature at the time of printing. Since this temperature needs to be high to some extent, it is a temperature at which the recording medium may be damaged such as being deformed or burnt. However, if the recording medium s body is transported, it will not be damaged because the time required for the temperature is limited. Therefore, if the recording medium is stopped while the temperature is the same as that temperature, the amount of heat on the recording medium may be excessive, and as a result, there is a risk that the recording medium may be deformed or burnt. .. Therefore, the control unit 400 sets the thermopile 17-4b to B ° C., which is a preheating control temperature at which the recording medium is not damaged even when the recording medium is stopped. In this embodiment, the difference temperature is controlled between A ° C., which is the control temperature during printing, and B ° C., which is the control temperature during preheating, but damage is caused even if the recording medium is stopped at A ° C. If it can be determined that the product is not damaged (or the damage is less than a predetermined reference value), the control unit 400 sets the same temperature as A ° C., which is the control temperature at the time of printing, and B ° C., which is the control temperature at the time of preheating. It may be controlled so that (d = 0, A = B).

Further, the values of A ° C., which is the control temperature at the time of printing, and B ° C., which is the control temperature at the time of preheating, change for each recording medium (for example, for each type of recording medium). For example, when the recording device 100 prints on recording media having different permeability, the non-permeable medium requires more energy for drying than the permeable medium, and therefore, at the time of printing. It is necessary to set the control temperature, A ° C., to a higher temperature. Further, when the heat resistant temperature of the recording medium is different, the value of B ° C., which is the control temperature at the time of preheating, also changes accordingly. Therefore, the value of the difference temperature d between the control temperature A ° C. at the time of printing and the control temperature B ° C. at the time of preheating also differs depending on the recording medium. Therefore, the control unit 400 stores the unique values of A ° C., which is the control temperature at the time of printing, and B ° C., which is the control temperature at the time of preheating, in a storage medium such as a memory for each recording medium, and depends on the recording medium to be used. To call these values and execute the above control. For example, depending on whether the type of recording medium is PVC or PET, as shown in Table 1 below, A ° C. (control temperature A), which is the control temperature during printing, and B ° C., which is the control temperature during preheating. (Control temperature B) can be set to different values.

In Table 1, the detection temperature 502 is set to a fixed value. However, the value of the detection temperature 502 may also differ depending on the difference in the position where the detection temperature 502 of the thermistor 17-4c and the B ° C., which is the control temperature at the time of preheating, are measured and the design layout. In such a case, the value of the detection temperature 502 of the thermistor 17-4c may be set in a range of approximately 50 to 100% with respect to B ° C., which is the control temperature at the time of preheating.

In addition, in order to speed up the preheating operation of the infrared heating device 17-4, as shown in FIG. 5, the control unit 400 stops the cure fan 17-4e (OFF) until it is determined that the preheating is completed. ), And when it is determined that the preheating is completed, the control signal 504 for operating (ON) the cure fan 17-4e may be output. By stopping the cure fan 17-4e, it is possible to prevent the infrared heater 17-4a and the reflector 17-4f from being cooled, and to complete the preheating quickly. Further, by operating the cure fan 17-4e after the preheating is completed, overheating inside the infrared heating device 17-4 can be suppressed.

Further, in the control unit 400, an operation terminal (not shown) such as a smartphone capable of communicating with the operation panel of the recording device 100 or the recording device 100 having a communication unit via wireless communication is operated by the user regarding the preheating operation (not shown). For example, when it is determined that the preheating time setting) has been accepted, the preheating operation of the recording device 100 may be executed according to the operation or the operation received by the communication unit via the wireless communication. With such control, the time of the preheating operation can be set, changed, and deleted by the user's intention, and it is possible to obtain a balance between the drying quality and the damage to the recording medium according to each user's individual request.
Further, when the same operation unit as described above is directed to the control unit 400, the control temperature at the time of preheating, which is the control temperature at the time of preheating, and the control temperature at the time of printing are received by the operation unit from the user for each type of recording medium. The heating of the recording medium may be controlled based on the A ° C. Thereby, these values can be set according to the individual request of each user.

As described above, in this embodiment, for example, when the drying control of the media and the ink is performed by using the industrial serial type inkjet printing apparatus, the heating means for heating the recording medium (for example, the infrared heating apparatus 17-). 4) and the heating means heats the recording medium with the first output (for example, B ° C. which is the control temperature at the time of preheating) at the time of preheating before the start of printing, and the temperature of the heating means becomes a predetermined threshold value (for example). When the preheating target temperature T) is reached, the heating means is used to heat the recording medium with a second output (for example, A ° C., which is a control temperature at the time of printing) that is equal to or higher than the first output. Since the control unit (for example, the control unit 400 having the CPU 401, FPGA 402, and motor driver 403) that controls and starts the transfer of the recording medium by the transfer means (for example, the transfer unit 405) is provided, damage to the media is avoided. Preheating control can be performed in consideration of the improvement of image quality. Specifically, it is possible to mitigate abrupt temperature changes on the media, suppress deformation of the media and cockling due to it, and suppress the occurrence of jam.

Further, the heating means includes an infrared heater 17-4a, a first temperature sensor (for example, thermopile 17-4b) that detects the temperature of the surface of the recording medium, and a second heating means that detects the temperature inside the heating means. (For example, thermista 17-4c), and the control unit continues the first output until the first temperature sensor detects the first temperature which is the control temperature at the time of preheating. When the second temperature sensor detects a temperature that becomes the predetermined threshold value, the output of the infrared heater is changed from the first output to the second output. Therefore, in a serial type inkjet recording device using a heating device that dries the ink on the medium, it is possible to satisfy the drying quality even for the image at the start of printing and prevent defects such as medium deformation and melting. It will be possible.

Further, the control unit performs heating by the first output and heating by the second output according to the type of the recording medium. Therefore, by giving a unique value according to the type of each medium, the drying quality can be ensured regardless of which medium is used, and damage to the medium can be suppressed.
Further, the heating means includes a fan (for example, cure fan 17-4e) that suppresses the heating of the heating means, and the control unit stops the fan until the temperature of the heating means reaches the predetermined threshold value. The fan is operated after the temperature of the heating means reaches a predetermined threshold value. Therefore, it is possible to prevent the portion where the infrared heater and the second temperature sensor are present from being cooled, and to complete the preheating quickly.

100 Infrared recording device 17 Drying part 17-1 Preheater 17-2 Print heater 17-3 Post heater 17-4 Infrared heating device 17-1a, 2a, 3a Thermistor 17-4 Infrared heating device 17-4b Thermopile 17-4c Thermistor ( Second temperature sensor)
17-4d Thermostat 17-4e Cure Fan 400 Control Unit 401 CPU
402 FPGA
403 Motor driver 404 Sub-scanning motor 405 Conveying unit 4051 Sub-scanning encoder sensor 4052 Conveying roller

Japanese Unexamined Patent Publication No. 08-146840

Claims (10)

The first heating means for heating the medium and
When the first heating means heats the medium at the first output during preheating and the temperature of the medium reaches a predetermined threshold value, the medium is heated at a second output which is equal to or higher than the first output. A control unit that controls the first heating means so as to heat and starts transporting the medium by the transport means.
A liquid discharge device comprising. The liquid discharge device according to claim 1, further comprising a second heating means for heating the liquid in contact with the medium during the preheating. The liquid discharge device according to claim 1 or 2, wherein the first heating means heats the medium from the surface. The liquid discharge device according to claim 1 or 2, wherein the second heating means heats the medium from the back surface. The liquid discharge device according to any one of claims 1 to 4, wherein the first heating means heats with far infrared rays. The liquid discharge device further includes a first temperature sensor that detects the temperature of the surface of the medium and a second temperature sensor that detects the temperature inside the heating means.
The control unit continues the first output until the second temperature sensor detects a preheating control temperature which is a control temperature at the time of preheating, and the first temperature sensor sets a temperature at which the predetermined threshold value is obtained. When detected, the output of the infrared heater is changed from the first output to the second output.
The liquid discharge device according to any one of claims 1 to 5. The liquid discharge device according to claim 6, wherein the predetermined threshold value is set in a range of approximately 50 to 100% of the preheating control temperature. The control unit performs heating by the first output and heating by the second output according to the type of the medium.
The liquid discharge device according to any one of claims 1 to 7. The heating means includes a fan that suppresses the heating of the heating means.
The control unit stops the fan until the temperature of the heating means reaches the predetermined threshold value, and operates the fan after the temperature of the heating means reaches the predetermined threshold value.
The liquid discharge device according to any one of claims 1 to 8. When the operation unit receives an operation related to the preheating operation from the user, the control unit controls the heating means so as to execute the preheating operation according to the operation.
The liquid discharge device according to any one of claims 1 to 9.

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