JP6471846B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming equipment.

  As an image forming apparatus, for example, a liquid discharge recording type apparatus using a liquid discharge head for discharging droplets as a recording head, for example, an ink jet recording apparatus is known.

  For example, devices capable of printing on non-penetrating media used in the sign graphics market have been developed. In such an apparatus, there is one that heats and dries the medium so that the ink is quickly dried.

  For example, a medium support unit that supports the print medium, a heater unit that heats and controls the print medium, and a temperature detection that is attached to the carriage and detects the surface temperature of the print medium along the relative movement direction with the relative movement by the carriage. And a temperature control means for controlling the surface temperature of the print medium to a predetermined set temperature by driving the heater means divided in the carriage movement direction based on the temperature detected by the temperature detection means. What is provided is known (patent document 1).

Republished patent WO11 / 024464

  However, the medium cannot be heated up to the set temperature or the temperature distribution is uneven in the plane of the medium due to the difference in thermal conductivity depending on the type of medium or the contact state between the heater and the medium. Heating unevenness such as becoming.

  For this reason, there is a problem that unevenness (image unevenness) occurs in image density, glossiness, and the like, resulting in a decrease in image quality.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce image unevenness and improve image quality.

To solve the above problems, an image forming apparatus according to the present onset Ming,
Droplet discharge means for discharging droplets to a medium;
A plurality of surface state detecting means for detecting a surface state of the medium to which the droplet is attached;
A first blowing means to blow out warm air to the medium,
A third air blower disposed above the image forming region by the droplet discharger and blowing out warm air;
Control means for driving the first air blowing means and the third air blowing means based on the detection result of the surface state detecting means to control the blowing of warm air;
The third air blowing means, the surface state detecting means, and the first air blowing means are arranged in this order along the medium conveyance direction .

  According to the present invention, image unevenness is reduced and image quality is improved.

1 is a side explanatory view of an image forming apparatus according to a first embodiment of the present invention. It is principal part plane explanatory drawing of the apparatus. It is front explanatory drawing with which it uses for description of an example of a medium temperature sensor. It is front explanatory drawing used for description of an example of a 1st warm air fan. It is block explanatory drawing of the control part of the apparatus. It is explanatory drawing with which it uses for description of the state (surface state) of the droplet on the printing medium in the same embodiment. It is a flowchart with which it uses for description of control of a 1st warm air fan. It is explanatory drawing explaining an example of the output reference table of the 1st warm air fan used by the same control. It is a flowchart with which it uses for description of control of the 1st warm air fan in 2nd Embodiment of this invention. It is explanatory drawing explaining an example of the output reference table of the 1st warm air fan used by the same control. It is side surface explanatory drawing of the image forming apparatus which concerns on 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory side view of the image forming apparatus, and FIG. 2 is an explanatory plan view of an essential part of the apparatus.

  This image forming apparatus is a serial type ink jet recording apparatus, and a print medium 2 as a medium is conveyed along a medium conveyance path 1.

  On the other hand, above the medium conveyance path 1, a carriage 5 on which a recording head 6 which is a liquid ejection means including a liquid ejection head is mounted is disposed so as to be reciprocally movable in the main scanning direction in FIG. Here, two recording heads 6 and 6 are mounted on the carriage 5.

  Then, droplets are ejected from the recording head 6 that reciprocally moves with respect to the print medium 2 that is intermittently conveyed through the medium conveyance path 1 to form an image on the print medium 2.

  A preheater 11, a platen heater 12, and a drying heater 13, which are heating means divided into a plurality of portions along the conveyance direction of the printing medium 2, are disposed below the medium conveyance path 1.

  Here, the preheater 11 is disposed in the pre-printing portion, the platen heater 12 is disposed in the printing region portion, and the drying heater 13 is disposed in the post-printing portion. In addition, although a heating means can also be arrange | positioned without dividing | segmenting into multiple, heating control can be performed finely by dividing | segmenting into multiple.

  On the downstream side of the carriage 5 in the medium conveyance direction, a medium temperature sensor 14 that is a temperature detection unit that detects the surface temperature of the print medium 2 as a surface state detection unit that detects the surface state of the print medium 2 to which droplets are attached. Is arranged.

  As will be described later, the medium temperature sensor 14 is divided into a plurality of blocks in a direction (width direction of the print medium 2) perpendicular to the medium conveyance direction, and the surface temperature of the print medium 2 immediately below is divided for each block. Is detected. That is, here, a plurality of blocks of the medium temperature sensor 14 constitute a temperature detection means that is a plurality of surface state detection means.

  A first hot air fan 15, which is a blowing unit that blows hot air toward the print medium 2, is disposed on the downstream side in the medium conveyance direction of the medium temperature sensor 14 so as to face the upstream side portion of the drying heater 13. Yes.

  Similar to the medium temperature sensor 14, the first hot air fan 15 is divided into a plurality of blocks in a direction orthogonal to the medium conveyance direction (width direction of the print medium 2), and an output (air volume) is provided for each block. ) Is controllable. That is, here, a plurality of blocks of the first hot air fan 15 constitute a plurality of air blowing means.

  A second hot air fan 16 is disposed downstream of the first hot air fan 15 in the medium conveying direction. The second warm air fan 16 blows uniform warm air in the width direction on the print medium 2 to completely dry the print medium 2 (printed matter).

  Next, an example of the medium temperature sensor will be described with reference to FIG. FIG. 3 is an explanatory front view for explaining the medium temperature sensor.

  The medium temperature sensor 14 is composed of N (a plurality of) non-contact temperature sensors S1 to SN arranged side by side in a direction intersecting the medium conveyance direction (here, a direction orthogonal). The temperature sensors S <b> 1 to SN measure the surface temperature t of each area (block) 1 to N of the print medium 2 that has been divided in advance.

  A difference Δt between the temperature (detected temperature) t measured by the temperature sensors S1 to SN and a preset set temperature is calculated, and the output (air volume) of the hot air fan 15 is determined based on the magnitude of the difference Δt. The

  As the temperature sensors S1 to SN, for example, a sensor that measures the temperature by detecting the amount of energy of infrared rays emitted from the print medium 2 can be used. Although not shown, medium detection means is disposed in the vicinity of the medium temperature sensor 14 to detect the presence or absence of the print medium 2.

  The medium temperature sensor 14 measures the surface temperature of each region 1 to N of the print medium 2 to detect the state of the liquid droplets landed on the print medium 2 (surface state of the medium). . Therefore, the surface state detection unit is not limited to the temperature detection unit that detects the surface temperature of the print medium 2, and may be any unit that detects the surface state of the print medium 2.

  Next, an example of the first warm air fan will be described with reference to FIG. FIG. 4 is an explanatory front view for explaining the first hot air fan.

  The first hot air fan 15 includes N (plural) hot air fans F <b> 1 to FN that are arranged side by side in a direction that intersects the medium conveyance direction (here, a direction that is orthogonal). The hot air fans F <b> 1 to FN blow (blow out) hot air toward the areas (blocks) 1 to N of the print medium 2.

  Each output (air volume) of the hot air fans F1 to FN is determined by the difference Δt calculated based on the detected temperatures of the respective regions 1 to N measured by the corresponding temperature sensors S1 to SN. Therefore, the outputs of the hot air fans F1 to FN are not uniform due to the surface temperature distribution of the print medium 2.

  Here, the temperature of the hot air fans F1 to FN is assumed to be the same and the air volume is individually controlled. However, both the temperature and the air volume can be individually controlled.

  Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. FIG. 5 is a block diagram of the control unit.

  The control unit 500 includes a CPU 501 that controls the entire apparatus, a ROM 502 that stores fixed data such as various programs including programs executed by the CPU 501, and a RAM 503 that temporarily stores image data and the like. In addition, the control unit 500 includes an ASIC 505 that processes various signal processing on image data, image processing that performs rearrangement, and other input / output signals for controlling the entire apparatus.

  In addition, the control unit 500 includes a host I / F 506 that transmits and receives data and signals to and from the host side, a data transfer unit that controls driving of the recording head 6, and a head drive control unit 508 that includes a drive signal generation unit. I have. The control unit 500 also includes a carriage motor 554 that moves and scans the carriage 5 and a motor drive control unit 510 that drives a medium transport motor 555 that drives a transport unit (not shown) that transports the print medium 2.

  In addition, the control unit 500 includes an I / O unit 513. A detection signal from each block of the medium temperature sensor 14, a detection signal from the heater temperature sensor 17 that detects the temperature of the preheater 11, the platen heater 12, and the drying heater 13 are input to the I / O unit 513. The I / O unit 513 also receives a detection signal from the encoder 556 that detects the movement of the carriage 5 and a detection signal from the wheel encoder 557 that detects the conveyance of the medium.

  In addition, the control unit 500 includes a heater control unit 521 that controls the preheater 11, the platen heater 12, and the drying heater 13, and a hot air fan control unit 522 that drives and controls the first hot air fan 15 and the second hot air fan 16. It has.

  The heater control unit 521 controls each temperature of the preheater 11, the platen heater 12, and the drying heater 13 based on the detection signal from the heater temperature sensor 17 so as to reach the target temperature.

  The hot air fan control unit 522 calculates a difference Δt calculated based on the detected temperatures of the regions 1 to N obtained from the detection signals from the temperature sensors S1 to SN of the medium temperature sensor 14, and the difference Δt is used to calculate the difference Δt. The output (air volume) of each warm air fan F1 to FN of the 1 warm air fan 15 is determined, and each warm air fan F1 to FN is driven and controlled. Further, the warm air fan control unit 522 controls the output (air volume) of the second warm air fan 16.

  The control unit 500 is connected to an operation panel 514 for inputting and displaying information necessary for the apparatus.

  Next, the air volume control in this embodiment will be described with reference to FIG. FIG. 6 is an explanatory diagram for explaining a state (surface state) of a droplet on the print medium.

  When the droplets land on the heated print medium 2, the moisture of the droplets evaporates. Since the speed at which the moisture of the droplets evaporates varies depending on the surface temperature of the print medium 2, the surface state of the droplets on the print medium 2 is predicted by detecting (measuring) the surface temperature of the print medium 2. be able to.

  Here, when the surface temperature of the print medium 2 is higher than the appropriate temperature, as shown in FIG. 6 (a), since the evaporation rate of the water in the droplet is high, the fluidity of the landing droplet is reduced, and the surface is It becomes rough. Therefore, in this case, by reducing the air volume output from the hot air fans F1 to FN of the first hot air fan 15, leveling (wetting and spreading of droplets) progresses even during the drying process, thereby smoothing the surface. To.

  On the other hand, when the surface temperature of the printing medium 2 is lower than the appropriate temperature, as shown in FIG. 6 (c), the evaporation rate of water in the droplet is slow, so that the landing droplet has sufficient fluidity and leveling. Progresses quickly and the surface becomes smooth. In this case, if the droplet (ink) spreads too much, problems such as bleeding occur. Therefore, by increasing the air volume output from the warm air fans F1 to FN of the first warm air fan 15, the drying speed is increased. , Suppress bleeding.

  On the other hand, when the surface temperature of the print medium 2 is an appropriate temperature, as shown in FIG. 6B, the leveling is progressing in a target state, and therefore, a predetermined air volume (set air volume: predetermined amount) is used. Blow warm air.

  Next, control of the first warm air fan will be described with reference to FIGS. FIG. 7 is a flowchart for explaining the control, and FIG. 8 is an explanatory diagram for explaining an example of an output reference table of the first hot air fan used in the control.

  Referring to FIG. 7, when the print medium 2 on which droplets have landed by the recording head 6 is detected by a medium detection unit (not shown), each region 1 of the print medium 2 is detected by each temperature sensor S <b> 1 to SN of the medium temperature sensor 14. Each surface temperature of ~ N is detected.

  And the difference (setting temperature difference) (DELTA) tn (n = 1-N) of each surface temperature tn (n = 1-N) and preset temperature (predetermined temperature) T is calculated about each detected area | region 1-N. .

  Thereafter, with respect to the set temperature difference Δtn of each region 1 to N, the output of the hot air fans F1 to FN corresponding to each region 1 to N is determined with reference to an output reference table as shown in FIG.

  In the output reference table shown in FIG. 8, the fan output has six stages A to F, and the fan outputs (air volumes) A to F have a relationship of A <B <C.

  Then, the hot air fans F1 to FN are driven with the determined fan output (fan output switching).

  Thereafter, when the print job is finished, the first hot air fan 15 is stopped.

  As described above, based on the detection results of the plurality of surface state detection units that detect the surface state of the medium to which the liquid droplets are attached, the plurality of blowing units are individually driven to control the blowing of warm air to the medium. As a result, uneven heating is reduced and image quality is improved.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a flowchart for explaining the control of the first hot air fan in the embodiment, and FIG. 10 is an explanatory diagram for explaining an example of the output reference table of the first hot air fan used in the control.

  In the present embodiment, first, the air volume V serving as a base is determined with reference to the type of the print medium 2 determined in advance by the user and the glossiness (output glossiness) of the printed matter to be output.

  The air volume V varies depending on the type of print medium and the output glossiness. To reduce the glossiness of the printed material to be output, the air volume V is relatively increased to leave some unevenness on the surface of the printed surface, and when the glossiness is given to the printed material, the surface of the printed surface is smoothed. Therefore, the air volume V is relatively small.

  As described in the first embodiment, when the print medium 2 on which droplets have landed by the recording head 6 is detected by a medium detection unit (not shown), the temperature sensors S1 to SN of the medium temperature sensor 14 are used. Each surface temperature of each region 1 to N of the print medium 2 is detected.

  And the difference (setting temperature difference) (DELTA) tn (n = 1-N) of each surface temperature tn (n = 1-N) and preset temperature (predetermined temperature) T is calculated about each detected area | region 1-N. .

  Thereafter, with respect to the set temperature difference Δtn of each region 1 to N, the output of the hot air fans F1 to FN corresponding to each region 1 to N is referred to with reference to a fan correction control output reference table as shown in FIG. decide.

  In the fan correction control output reference table shown in FIG. 10, six levels of correction of “+ a”, “+ b”, “+ c”, “−a”, “−b”, and “−c” with respect to the base air volume V are performed. It is configured to add. The corrected air volume is a <b <c.

  Then, the hot air fans F1 to FN are driven with the determined fan output (fan output switching).

  Thereafter, when the print job is finished, the first hot air fan 15 is stopped.

  Thereby, heating unevenness is reduced and image unevenness is reduced, and a desired glossiness can be obtained, and image quality is improved.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory side view of the image forming apparatus according to the embodiment.

  In the present embodiment, a glossiness sensor 18 serving as a surface state detection unit that detects the glossiness of the print medium 2 is disposed downstream of the carriage 5 in the medium conveyance direction. The glossiness sensor 18 also detects the glossiness in a plurality of blocks (areas 1 to N), similarly to the medium temperature sensor 14.

  Further, a third hot air fan 19 for gloss control is disposed above the image forming area formed by the recording head 6.

  Then, by blowing warm air from the third warm air fan 19 to the printing medium 2 from the time of printing to the end, the degree of drying can be controlled from the stage immediately after the droplets land and the glossiness can be controlled. . Thereby, the gloss control range of printed matter can be widened.

  At this time, the air volume of the third warm air fan 19 is determined by the type of the print medium 2 and the glossiness of the printed matter to be output.

  Further, the air volume control of the first hot air fan 15 is performed based on the detection result of the glossiness sensor 18. Thereby, image unevenness can be reduced.

  In the present application, image formation, recording, printing, printing, and printing are all synonymous. The “image forming apparatus” means an apparatus that forms an image by discharging a liquid onto a medium. In addition, “image formation” not only applies an image having a meaning such as a character or a figure to a medium but also applies an image having no meaning such as a pattern to the medium (simply applying a droplet to the medium). It also means to land on. The term “ink” is not limited to what is called an ink unless specifically limited, and is used as a general term for all liquids that can perform image formation. For example, DNA samples, resists, pattern materials, resins and the like are also included.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

2 Print medium 5 Carriage 6 Recording head (liquid ejection head)
14 Medium temperature sensor (surface condition detection means)
15 First hot air fan (air blowing means)
16 Second hot air fan 18 Glossiness sensor (surface state detection means)
19 3rd hot air fan S1-S2 Temperature sensor F1-FN Hot air fan 500 Control part

Claims (1)

Droplet discharge means for discharging droplets to a medium;
A plurality of surface state detecting means for detecting a surface state of the medium to which the droplet is attached;
First air blowing means for blowing warm air to the medium;
A third air blower disposed above the image forming region by the droplet discharger and blowing out warm air;
Control means for driving the first air blowing means and the third air blowing means based on the detection result of the surface state detecting means to control the blowing of warm air;
An image forming apparatus, wherein the third air blowing unit, the surface state detecting unit, and the first air blowing unit are arranged in this order along the conveyance direction of the medium.

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