JP5318015B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that suppresses temperature fluctuations generated by a hollow portion of a drum that conveys a recording medium.

  As shown in the following patent documents, various techniques are disclosed regarding temperature management and ventilation by a fan. For example, Patent Document 1 discloses a measurement apparatus including a gas supply source that generates a gas flow having a temperature stabilized and a substantially constant velocity, and an air guide unit that guides the gas flow across the beam. The fluctuation of the measured value of the interferometer due to the refractive index fluctuation is reduced.

  Patent Document 2 discloses a technique for reducing fluctuations in measurement values of an interferometer due to fluctuations in the refractive index of air by introducing a gas flow whose temperature is stabilized.

  Further, Patent Document 3 discloses an exposure apparatus that detects a focal position without being affected by air fluctuation due to heat generation of a wafer stage. Any one of a vicinity of a blow-out port through which air-conditioned gas is blown and / or a suction port for suction, near an optical path of an exposure light beam of the projection optical system, and an optical path of a light beam of the focal position detection system. A technique for providing a temperature sensor and / or a wind speed sensor at more than one location is disclosed.

  Patent Document 4 discloses a technique for supplying outside air from the outside of the housing to prevent refraction of the light beam.

  Patent Document 5 discloses a technique for preventing refraction by blowing so that a temperature gradient does not occur in the air on the optical path of the light beam.

  Patent Document 6 discloses a turbulent flow generation device in which a fan makes a disturbance of an air flow that eliminates a refractive index variation of an air layer in the optical path to remove a variation in light intensity distribution.

  Patent Document 7 discloses a technique for controlling the temperature change of the optical path deflecting element by controlling the air flow rate / air temperature based on the detected temperature of the external / internal temperature sensor.

  In Patent Document 8, the shutter is opened at the time of copying, and at the same time, outside air is introduced into the housing by a fan to prevent dirt and dust from adhering to the mirror and the lens.

  As described above, Patent Documents 1 and 2 relate to measuring apparatuses such as position detection and distance detection, which are techniques for reducing fluctuations in measured values due to air refractive index fluctuations by blowing gas so as to cross the beam light. Further, Patent Documents 3 to 7 prevent fluctuations by a method such as sending outside air into the wear stage and the housing and stirring the inside. This is a technology that has air-conditioning means, controls the blast temperature, and eliminates the temperature gradient.

  Japanese Patent Laid-Open No. 2004-228561 has a content of introducing outside air by a fan into the housing to prevent the mirror and the lens from being soiled.

  Both prevent position detection misalignment, focus position misalignment, and false detection caused by light fluctuations caused by the difference in refractive index due to the temperature gradient of air existing in the optical path of the light beam inside the device. Content.

Japanese Patent Laid-Open No. 01-018002 Japanese Patent Laid-Open No. 09-166415 JP 2001-250759 A JP 2007-011032 A Japanese Patent Laid-Open No. 2006-267962 Japanese Patent Publication No. 6-72982 JP 2004-279924 A Japanese Utility Model Publication No. 04-024746

  In such a technical background, an ink jet recording apparatus or the like often employs a system in which a medium is wound (adsorbed) and conveyed around a drum, but the sheet is in a state of floating from the drum when the sheet is conveyed. This may be erroneously detected when detected using a laser beam.

  The gripper that grips the paper has a dent in the structure, and in order to keep the temperature of the drum at a high level by warming the drum to dry the ink after droplet ejection, there is a temperature difference in the dent. It is easy to create a certain air layer. In particular, the suction drum until the conveyance of the paper is started is in a standby state, and is in a stopped state or at a low rotation speed. There is a problem that the occurrence of a temperature layer in the depression causes light fluctuations, leading to erroneous detection.

  As described above, the conventional technique has a problem that temperature fluctuation occurs due to the hollow portion of the drum that conveys the recording medium.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image forming apparatus capable of suppressing temperature fluctuations generated by a hollow portion of a drum that conveys a recording medium.

  In order to achieve the above object, the invention described in claim 1 has a hollow portion provided with a grip portion for gripping a recording medium on which an image is formed, and grips the recording medium by the grip portion. Accordingly, a conveying drum that conveys the recording medium, a blowing unit that blows air to the depression, a drum temperature detecting unit that detects the temperature of the conveying drum, and the conveying drum that is detected by the drum temperature detecting unit Control means for controlling the air blowing means so as to blow air to the recess when the temperature exceeds a predetermined threshold value.

  According to the first aspect of the present invention, the conveyance drum has a hollow portion provided with a grip portion for gripping a recording medium on which an image is formed, and the gripping portion grips the recording medium. The recording medium is transported by the air, blown to the hollow portion by the air blowing means, the temperature of the transport drum is detected by the drum temperature detecting means, and the temperature of the transport drum detected by the drum temperature detecting means is detected by the control means. When the temperature exceeds a predetermined threshold value, the air blowing means is controlled so as to blow air to the hollow portion, so that temperature fluctuations generated by the hollow portion of the drum that conveys the recording medium can be suppressed. An image forming apparatus can be provided.

  The invention described in claim 2 is the invention described in claim 1, further comprising a proximity temperature detecting means for detecting a temperature in the vicinity of the transport drum, wherein the control means is controlled by the drum temperature detecting means. When the absolute value of the difference between the detected temperature of the conveying drum and the temperature of the vicinity of the conveying drum detected by the vicinity temperature detecting means exceeds a predetermined threshold value, air is blown to the hollow portion. And further controlling the air blowing means.

  According to the second aspect of the present invention, the absolute value of the difference between the temperature of the transport drum detected by the drum temperature detection unit and the temperature of the vicinity of the transport drum detected by the vicinity temperature detection unit is set in advance. Since the air blowing unit is further controlled to blow air to the hollow portion when a predetermined threshold value is exceeded, image formation capable of suppressing temperature fluctuations generated by the hollow portion of the drum that conveys the recording medium An apparatus can be provided.

  The invention according to claim 3 is the invention according to claim 2, wherein whether or not the recording medium floats from the surface of the transport drum is determined in the direction of the rotation axis of the transport drum. It further has a float detection means for detecting by irradiating laser light so as to pass through the vicinity, and the temperature detection means detects the temperature of the optical path of the laser light as the temperature in the vicinity of the transport drum.

  According to the invention of claim 3, when detecting the floating of the recording medium with a laser beam or the like that is easily affected by temperature fluctuation, it is possible to suppress false detection by suppressing the temperature fluctuation. It becomes.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the control means is configured such that the amount of air blown by the air blowing means increases as the rotational speed of the transport drum increases. The air blowing means is controlled so as to reduce.

  According to the fourth aspect of the present invention, when the rotation speed of the transport drum is high, there is a high possibility that the image is being formed. Since the image quality is deteriorated by affecting the discharge trajectory, it is possible to suppress the image quality deterioration by reducing the air flow rate.

  Further, in the invention according to claim 5, in the invention according to any one of claims 1 to 3, the control means, when the image is formed on the recording medium, Compared to the case where the recording medium is not formed, the blowing unit is controlled so as to reduce the amount of blowing by the blowing unit.

  According to the fifth aspect of the present invention, if the amount of blown air is not reduced when an image is being formed, the recording medium may be wavy or the droplet ejection trajectory may be affected, thereby deteriorating the image quality. Therefore, it is possible to suppress deterioration in image quality by reducing the amount of air blown.

  The invention described in claim 6 is the invention described in any one of claims 1 to 5, wherein the air blowing means is provided with a fan having a constant air flow rate and a fan having a variable air flow rate. It is a thing.

  According to the sixth aspect of the present invention, by providing a fan with a constant air flow rate and a fan with a variable air flow rate, the drum that conveys the recording medium more than when the air is blown by one fan is provided. Temperature fluctuations generated by the depression can be suppressed.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the blowing means is provided with a plurality of fans for blowing air from different positions.

  According to invention of Claim 7, it becomes possible to suppress the fluctuation | variation of temperature more by ventilating from a different position.

  According to the present invention, there is an effect that it is possible to provide an image forming apparatus capable of suppressing temperature fluctuation generated by a hollow portion of a drum that conveys a recording medium.

1 is a side view illustrating an overall configuration of an ink jet recording apparatus according to an embodiment. It is a figure which shows the system configuration | structure of an inkjet recording device. It is a plane perspective view which shows the structural example of a head. It is a perspective view of a conveyance drum. It is sectional drawing of a conveyance drum. It is a figure which shows the front view of a conveyance drum, and the cross section of a conveyance drum and an air blower. It is a figure which shows the structural example which provided the some fan. It is a flowchart which shows the flow of a ventilation process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, a droplet may be expressed as ink.

  FIG. 1 is an overall configuration diagram of an ink jet recording apparatus showing an embodiment of an image forming apparatus of the present invention. As shown in the figure, the ink jet recording apparatus 10 includes a paper feeding / conveying section 12 that feeds and conveys paper P to the upstream side in the conveyance direction of a sheet P (hereinafter referred to as “paper”) as a recording medium. Is provided. A processing liquid application unit 14 that applies a processing liquid to an image recording surface (hereinafter also referred to as “recording surface”) of the paper P along the conveyance direction of the paper P, on the downstream side of the paper feed conveyance unit 12. An image recording unit 16 for recording an image on the recording surface of the paper P, an ink drying unit 18 for drying the image recorded on the recording surface, an image fixing unit 20 for fixing the dried image on the paper P, and a paper P on which the image is fixed The discharge part 21 which discharges is provided.

  The paper feeding / conveying unit 12 is provided with a stacking unit 22 on which the sheets P are stacked, and a sheet feeding unit that feeds the sheets P stacked on the stacking unit 22 one by one on the stacking unit 22. A portion 24 is provided. A transport unit 28 including a plurality of pairs of rollers 26 is provided on the downstream side in the transport direction of the paper P of the paper feed unit 24 (hereinafter, the “transport direction of the paper P” may be omitted). ing. The paper P fed by the paper feed unit 24 is transported to the processing liquid coating unit 14 through a transport unit 28 composed of a plurality of pairs of rollers 26.

  In the treatment liquid application unit 14, a treatment liquid application drum 30 is rotatably disposed. The processing liquid coating drum 30 is provided with a gripper (gripping part) 32 that grips the paper P by sandwiching the leading end of the paper P, and the surface of the processing liquid coating drum 30 is interposed via the gripper 32. With the paper P held, the paper P is transported to the downstream side by the rotation of the treatment liquid coating drum 30.

  Note that the intermediate transport drum 34, the image recording drum 36, the ink drying drum 38, and the fixing drum 40, which will be described later, are provided with a gripper 32, similar to the processing liquid coating drum 30. The gripper 32 delivers the paper P from the upstream drum to the downstream drum. In the following description, the treatment liquid coating drum 30, the intermediate conveyance drum 34, the image recording drum 36, the ink drying drum 38, and the fixing drum 40 may be collectively expressed as a conveyance drum 100.

  A processing liquid coating device 42 and a processing liquid drying device 44 are disposed on the upper portion of the processing liquid coating drum 30 along the circumferential direction of the processing liquid coating drum 30. A treatment liquid is applied to the recording surface, and the treatment liquid drying device 44 dries the treatment liquid.

  Here, the treatment liquid reacts with the ink to aggregate the color material (pigment) and has an effect of promoting separation of the color material (pigment) and the solvent. The treatment liquid application device 42 is provided with a storage portion 46 for storing the treatment liquid, and a part of the gravure roller 48 is immersed in the treatment liquid.

  A rubber roller 50 is disposed in pressure contact with the gravure roller 48, and the rubber roller 50 comes into contact with the recording surface side of the paper P to apply the processing liquid. Further, a squeegee (not shown) is in contact with the gravure roller 48 to control the amount of treatment liquid applied to the recording surface of the paper P.

  Ideally, the treatment liquid film thickness is sufficiently smaller than the droplets of the head droplets. For example, when the droplet volume is 2 pl, the average diameter of the droplets of the head droplet is 15.6 μm, and when the treatment liquid film thickness is thick, the ink dots float in the treatment liquid without contacting the recording surface of the paper. To do. In order to obtain a landing dot diameter of 30 μm or more with a droplet ejection amount of 2 pl, it is preferable to set the treatment liquid film thickness to 3 μm or less.

  On the other hand, in the treatment liquid drying device 44, a hot air nozzle 54 and an infrared heater 56 (hereinafter referred to as “IR heater 56”) are disposed close to the surface of the treatment liquid application drum 30. A solvent such as water in the processing liquid is evaporated by the hot air nozzle 54 and the IR heater 56 to form a solid or thin film processing liquid layer on the recording surface side of the paper P. By thinning the treatment liquid in the treatment liquid drying step, the dots ejected by the ink in the image recording unit 16 come into contact with the surface of the paper P to obtain a necessary dot diameter, and the thinned treatment liquid An action of reacting and aggregating the color material and fixing to the surface of the paper P is easily obtained.

  Thus, the paper P on which the processing liquid has been applied to the recording surface and dried by the processing liquid application unit 14 is conveyed to an intermediate conveyance unit 58 provided between the processing liquid application unit 14 and the image recording unit 16. .

  An intermediate transport drum 58 is rotatably provided in the intermediate transport unit 58, and the sheet P is held on the surface of the intermediate transport drum 34 via the gripper 32 provided in the intermediate transport drum 34. The sheet P is conveyed to the downstream side by the rotation of 34.

  An image recording drum 36 is rotatably provided in the image recording unit 16, and the sheet P is held on the surface of the image recording drum 36 via a gripper 32 provided on the image recording drum 36, and the image recording drum The sheet P is conveyed downstream by the rotation of 36.

  Above the image recording drum 36, a head unit 66 composed of a single-pass inkjet line head (hereinafter simply referred to as “head”) 64 is disposed in the vicinity of the surface of the image recording drum 36. ing. In this head unit 66, at least basic color YMCK heads 64 are arranged along the circumferential direction of the image recording drum 36, and each color is formed on the processing liquid layer formed on the recording surface of the paper P by the processing liquid coating unit 14. Record images.

  The treatment liquid has an effect of aggregating the color material (pigment) and latex particles dispersed in the ink into the treatment liquid, and forms an aggregate on the paper P that does not generate a color material flow. As an example of the reaction between the ink and the treatment liquid, an acid is contained in the treatment liquid, the pigment dispersion is destroyed by PH down, and a color material bleeds using a mechanism of agglomeration to avoid color mixing between the color inks.

  The head 64 performs droplet ejection in synchronization with an encoder (not shown) that detects the rotational speed disposed on the image recording drum 36, thereby determining the landing position with high accuracy, as well as vibration of the image recording drum 36, Irregular droplet ejection can be reduced without depending on the accuracy of the rotary shaft 68 and the drum surface speed.

  The head unit 66 can be retracted from the upper part of the image recording drum 36, and maintenance operations such as cleaning of the nozzle (discharge port) surface of the head 64 and discharging of thickened ink cause the head unit 66 to move to the image recording drum 36. Implemented by retreating from the top.

  The inkjet recording apparatus 10 includes an ink storage / loading unit 65 that stores ink to be supplied to each of the YMCK heads 64. The ink storage / loading unit 65 has an ink tank that stores ink of a color corresponding to each of the YMCK heads 64, and each tank communicates with the YMCK heads 64 via a predetermined pipe line.

  The sheet P on which the image is recorded on the recording surface in the image recording unit 16 is conveyed to an intermediate conveyance unit 70 provided between the image recording unit 16 and the ink drying unit 18 by the rotation of the image recording drum 36. The intermediate transport unit 70 has substantially the same configuration as that of the intermediate transport unit 58, and a description thereof will be omitted.

  An ink drying drum 38 is rotatably provided in the ink drying unit 18, and a plurality of hot air nozzles 72 and IR heaters 74 are arranged on the upper portion of the ink drying drum 38 in proximity to the surface of the ink drying unit 18. It is installed.

  Here, as an example, the pair of IR heaters 74 arranged in parallel with the hot air nozzles 72 are alternately arranged so that the hot air nozzles 72 are arranged on the upstream side and the downstream side. In addition to this, a large number of IR heaters 74 are arranged on the upstream side to irradiate a large amount of heat energy on the upstream side to increase the temperature of moisture, and a large number of hot air nozzles 72 are arranged on the downstream side to blow off saturated water vapor. Also good.

  Here, the hot air nozzle 72 is arranged so that the blowing angle of the hot air is inclined toward the rear end side of the paper P. Accordingly, the flow of hot air from the hot air nozzle 72 can be collected in one direction, and the paper P is pressed against the ink drying drum 38 side, and the state where the paper P is held on the surface of the ink drying drum 38 is maintained. be able to.

  In the portion where the image on the paper P is recorded by the hot air from the hot air nozzle 72 and the IR heater 74, the solvent separated by the color material aggregating action is dried to form a thin image layer.

  Although the warm air varies depending on the conveyance speed of the paper P, it is normally set to 50 ° C. to 70 ° C., and the ink surface temperature is set to 50 ° C. to 60 ° C. by setting the temperature of the IR heater 74 to 200 ° C. to 600 ° C. It is set to be. The evaporated solvent is discharged to the outside of the inkjet recording apparatus 10 together with air, but the air is discharged. This air may be cooled by a cooler / radiator or the like and discharged as a liquid.

  The paper P on which the image on the recording surface has been dried is conveyed to an intermediate conveyance unit 76 provided between the ink drying unit 18 and the image fixing unit 20 by the rotation of the ink drying drum 38. Since the configuration is substantially the same as that of the intermediate conveyance unit 58, description thereof is omitted.

  The image fixing unit 20 is rotatably provided with an image fixing drum 40. The image fixing unit 20 heats / pressurizes latex particles in a thin image layer formed on the ink drying drum 38. And has a function of fixing and fixing on the paper P.

  A heating roller 78 is disposed above the image fixing drum 40 in the vicinity of the surface of the image fixing drum 40. The heating roller 78 has a halogen lamp incorporated in a metal pipe made of aluminum or the like having a good thermal conductivity. The heating roller 78 applies heat energy equal to or higher than the Tg temperature of the latex. As a result, the latex particles are melted and pressed into the irregularities on the paper for fixing, and the irregularities on the image surface are leveled to obtain glossiness.

  A fixing roller 80 is provided on the downstream side of the heating roller 78. The fixing roller 80 is disposed in pressure contact with the surface of the image fixing drum 40 so as to obtain a nip force with the image fixing drum 40. I have to. Therefore, at least one of the fixing roller 80 and the image fixing drum 40 has an elastic layer on the surface and a uniform nip width with respect to the paper P.

  The sheet P on which the image on the recording surface is fixed by the above-described steps is conveyed to the discharge unit 21 provided on the downstream side of the image fixing unit 20 by the rotation of the image fixing drum 40.

  In this embodiment, the image fixing unit 20 has been described. However, the image fixing unit 20 is not necessarily required because it is sufficient that the image formed on the recording surface can be dried and fixed by the ink drying unit 18.

  Next, the system configuration of the inkjet recording apparatus 10 according to the present embodiment will be described with reference to FIG.

  As shown in the figure, the inkjet recording apparatus 10 includes a communication interface 83, a system controller 84, an image memory 85, a ROM 86, a motor driver 87, a heater driver 88, a fan / motor driver 81, a print control unit 89, a ROM 94, and an image. A buffer memory 90, an image processing unit 91, a head driver 92, a proximity temperature detection unit 114, a drum temperature detection unit 116, an irradiation unit 106, a light receiving unit 108, and the like are provided.

  The communication interface 83 is an interface unit with the host device 99 that is used by a user to instruct the inkjet recording apparatus 10 to form an image. As the communication interface 83, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted.

  Image information sent from the host device 99 is taken into the inkjet recording apparatus 10 via the communication interface 83 and temporarily stored in the image memory 85. The image memory 85 is a storage unit that stores image data input via the communication interface 83, and information is read and written through the system controller 84. The image memory 85 is not limited to a memory made of semiconductor elements, and a magnetic medium such as a hard disk may be used.

  The system controller 84 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 84 includes a communication interface 83, an image memory 85, a motor driver 87, a heater driver 88, a fan / motor driver 81, a proximity temperature detection unit 114, a drum temperature detection unit 116, an irradiation unit 106, a light reception unit 108, and the like. Each part is controlled to control communication with the host device 99, read / write control of the image memory 85 and ROM 86, and generate control signals for controlling the motor 93 and IR heaters 56 and 74 of the paper transport system. In addition to the control signal, image data stored in the image memory 85 is transmitted to the print control unit 89.

  The ROM 86 stores programs executed by the CPU of the system controller 84 and various data necessary for control. The ROM 86 may be a non-rewritable storage unit, but when various types of data are updated as necessary, it is preferable to use a rewritable storage unit such as an EEPROM.

  The image memory 85 is used as a temporary storage area for image information, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 87 is a driver (drive circuit) that drives the paper transport motor 93 in accordance with an instruction from the system controller 84. The heater driver 88 is a driver that drives the IR heaters 56 and 74 in accordance with instructions from the system controller 84. Details of the vicinity temperature detection unit 114, the drum temperature detection unit 116, the irradiation unit 106, and the light receiving unit 108 will be described later.

  The fan / motor driver 81 is a driver that drives each fan / motor 73 and the fan / motor connection circuit 71 in accordance with an instruction from the system controller 84.

  On the other hand, the print control unit 89 includes a CPU and its peripheral circuits, and generates an ejection control signal from image data in the image memory 85 in cooperation with the image processing unit 91 according to the control of the system controller 84. In addition to performing various processes and corrections for this purpose, the generated ink discharge data is supplied to the head driver 92 to control the discharge drive of the head unit 66.

  The print controller 89 is connected to a ROM 94 that stores programs executed by the CPU of the print controller 89 and various data necessary for control. The ROM 94 may also be a non-rewritable storage means, but when various data are updated as necessary, it is preferable to use a rewritable storage means such as an EEPROM.

  The image processing unit 91 generates dot arrangement data for each ink color from the input image information, and performs high-quality dot positions by performing halftoning processing (intermediate gradation processing) on the input image information. decide.

  In FIG. 2, the image processing unit 91 is illustrated as being separate from the system controller 84 and the print control unit 89, but for example, the image processing unit 91 is included in the system controller 84 or the print control unit 89. However, you may make it comprise the part.

  Further, the print control unit 89 generates ink discharge data (actuator control signal corresponding to the nozzles of the head 64) based on the dot arrangement data corresponding to the recording rate generated by the image processing unit 91. It has a generation function and a drive waveform generation function.

  The ink discharge data generated by the ink discharge data generation function is given to the head driver 92, and the ink discharge operation of the head unit 66 is controlled.

  The print control unit 89 includes an image buffer memory 90, and image data, parameters, and other data are temporarily stored in the image buffer memory 90 during image information processing in the print control unit 89. In particular, the image buffer memory 90 is a storage unit that stores image data indicating the recording rate of each pixel in an image formed on a sheet. In FIG. 2, the image buffer memory 90 is shown in a mode associated with the print control unit 89, but it can also be used as the image memory 85.

  Also possible is an aspect in which the print control unit 89 and the system controller 84 are integrated and configured with one processor.

  FIG. 3 is a perspective plan view showing a structural example of the head 64. In order to increase the dot pitch printed on the paper, it is necessary to increase the nozzle pitch in the head 64. The head 64 of this example includes a plurality of nozzles 151 serving as ink discharge ports and a plurality of ink chamber units (droplet discharge elements) 153 including pressure chambers 152 corresponding to the nozzles 151 in a staggered matrix (2 It has a structure that is arranged in a dimensional manner, thereby increasing the density of the substantial nozzle interval (projection nozzle pitch) projected so as to be aligned along the longitudinal direction of the head (direction perpendicular to the paper feed direction). Has achieved. The head 64 is configured to eject ink onto the paper in a predetermined order from each of the plurality of nozzles 151 that eject ink.

  Thus, the head 64 is provided with a plurality of nozzles 151 for ejecting ink droplets arranged side by side in the transport direction of the paper on which ink droplets are ejected and in the intersecting direction intersecting the transport direction.

  Next, the conveyance drum 100 will be described with reference to FIG. FIG. 4 is a perspective view of the transport drum 100. In this figure, for the sake of simplicity of explanation, a floating detection device and the like to be described later are omitted. As shown in the figure, the transport drum 100 is an impression body. As shown in FIG. 6A, the paper is conveyed from the bottom in the direction of the arrow. At this time, as shown in FIG. 5B, the conveyance drum 100 holds the paper on which the image is formed. The gripper 36 is provided with a recess 102, and the sheet is conveyed by being gripped by the gripper 36. In order to operate the gripper 36, a recess 102 shown in the figure is provided, and the recess 102 causes temperature fluctuations.

  Next, a cross section of the transport drum 100 will be described with reference to FIG. FIG. 5 is a cross-sectional view of the transport drum 100, where FIG. 5A shows the entire transport drum 100, and FIG. 5B is an enlarged view of the vicinity of the gripper 36.

  As shown in FIG. 6A, the conveyance drum 100 according to the present embodiment is provided with the recess 102 and the gripper 36 at positions shifted by 180 degrees. As shown in FIG. 5B, the gripper 36 is substantially L-shaped, and grips the leading edge of the paper by the claw shape of the leading edge. The gripper 36 grips and releases the paper by performing an opening / closing operation in response to driving of a cam (not shown).

  Next, the positional relationship between the blower and the transport drum 100 will be described with reference to FIG. FIG. 6A is a front view of the transport drum 100, and FIG. 6B is a diagram illustrating a cross section of the transport drum 100 and the blower 104.

  FIG. 4A shows the transport drum 100, the blower 104, the irradiation unit 106, the light receiving unit 108, the vicinity temperature detection unit 114, and the drum temperature detection unit 116. The blower 104 blows air to the conveyance drum 100, and consequently blows air to the hollow portion 102. In the case of this figure, the blower 104 is provided with six fans 112 in the direction of the rotation axis of the transport drum 100, so that air can be blown in the entire direction of the rotation axis of the transport drum 100. The irradiation unit 106 irradiates a laser beam so as to pass through the vicinity of the surface of the conveyance drum 100 in the direction of the rotation axis of the conveyance drum 100 whether or not the sheet is floating from the surface of the conveyance drum 100. Here, the vicinity of the surface means an area within a distance from the conveyance drum 100 where it is possible to detect that the sheet is floating from the conveyance drum 100 because the laser beam is used to detect the floating of the sheet. .

  The light receiving unit 108 receives the laser light emitted from the irradiation unit 106. When the sheet floats from the surface of the conveyance drum 100, the laser beam emitted from the irradiation unit 106 cannot be received by the light receiving unit 108. Accordingly, the system controller 84 determines that there is no floating when the laser light emitted from the irradiation unit 106 can be received by the light receiving unit 108. The irradiation unit 106 and the light receiving unit 108 may be collectively expressed as a floating detection unit.

  The vicinity temperature detection unit 114 detects the temperature in the vicinity of the transport drum 100. In the present embodiment, the vicinity temperature detection unit 114 particularly detects the temperature of the optical path of the laser light. The temperature detector 116 is provided inside the transport drum 100 and detects the temperature of the transport drum 100.

  In addition, since the air in the space of the hollow portion 102 is warmed by the transport drum 100, the air at a temperature different from the vicinity of the transport drum 100 (normally higher than the surroundings) is stagnant. When the gripper 36 passes through the above-described floating detection unit, temperature fluctuation occurs due to the optical path of the laser beam and the depression 102, so that the laser beam is refracted and deviates from the light receiving point of the light receiving unit 108. It is determined that the light is shielded (the sheet is floating), leading to erroneous detection. It has been found that this phenomenon occurs remarkably when the transport drum 100 before transporting the paper is stopped and rotating at a low speed.

  Therefore, as shown in FIG. 5B, the air is blown by the fan 112 provided in the blower device 104, whereby the air in the recess of the gripper 36 is agitated to suppress temperature fluctuation. In the figure, the wind by the fan 112 provided in the blower 104 is discharged toward the transport drum 100 through the duct as indicated by an arrow.

  The fan 112 of the blower 104 is controlled by a fan / motor driver 81 and a fan / motor connection circuit 71 connected to the system controller 84 described above. The system controller 84 performs control so that the amount of air blown by the blower 104 is reduced as the number of rotations of the transport drum 100 increases.

  This is because if the agitation is performed with strong wind while the paper is being conveyed by the conveyance drum 100, the air current is blocked by the paper, so that sufficient agitation cannot be performed. Further, if the air is blown with a strong wind, the sheet is blown by the wind, and further, the air flow is restricted. Therefore, the air flows near the head unit 66 and is adsorbed in a undulated state when adsorbed to the transport drum 100. For this reason, wrinkles and adsorption positions are easily misaligned, which affects the ink ejection trajectory during image formation, making it impossible to land ink droplets at accurate positions, and image distortion and position. This is because there is a concern that the image quality deteriorates due to the occurrence of misalignment or registration misalignment.

  Therefore, when the temperature of the transport drum 100 exceeds a predetermined threshold value (for example, about 40 ° C.), air is blown to the hollow portion 102.

  Further, when there is no large difference between the temperatures of the transport drum 100 and the vicinity of the transport drum 100 (for example, the difference is less than 5 degrees), even if temperature fluctuation occurs, the temperature is slight. Therefore, the absolute value of the difference between the temperature of the conveyance drum 100 detected by the vicinity temperature detection unit 114 and the drum temperature detection unit 116 and the temperature in the vicinity of the conveyance drum 100 is a predetermined threshold (for example, about 5 ° C. to 10 ° C. ) May be blown to the hollow portion 102. As a result, it is possible to avoid unnecessary power consumption without affecting the ink ejection trajectory and excessive power consumption.

  The air blower 104 described with reference to FIG. 6 is blown by one fan 112 having a variable air flow rate, but as shown in FIG. 7, a fan 120 having a constant air flow rate and a fan 122 having a variable air flow rate. May be provided.

  In this case, for example, when the absolute value of the temperature difference exceeds a predetermined threshold value, air is blown by the fan 120, and when the temperature value greatly exceeds the threshold value, the fan 122 controls the air flow rate according to the absolute value of the temperature difference. Thus, the system controller 84 controls.

  Further, as shown in the figure, a plurality of fans 120 and 122 that blow air from different positions are provided (in this case, the air volume of the fan 122 is not necessarily variable), and air is blown from different positions. Thus, it becomes possible to suppress temperature fluctuation.

  The flow of the air blowing process by the system controller 84 described above will be described with reference to the flowchart of FIG. In this flowchart, the absolute value of the difference between the temperature of the conveyance drum 100 detected by the proximity temperature detection unit 114 and the drum temperature detection unit 116 and the temperature in the vicinity of the conveyance drum 100 exceeds a predetermined threshold. The flow of the ventilation process which ventilates with respect to the hollow part 102 is shown.

  First, in step 101, the drum temperature detection unit 116 detects the temperature A of the transport drum, and the vicinity temperature detection unit 114 detects the temperature B near the transport drum. In the next step 102, it is determined whether or not the difference between the absolute values of the temperature A and the temperature B exceeds a predetermined threshold T. This predetermined threshold T varies depending on the shape of the transport drum 100, the depression 102, etc., the temperature during operation of the transport drum 100, etc., the model, individual differences, and the environment. desirable.

  If a negative determination is made in step 102, the process returns to step 101 again. On the other hand, if an affirmative determination is made in step 102, it is determined in step 103 whether the transport drum 100 is stopped. In addition, when the conveyance drum 100 is stopped, it is more effective to stop the recessed portion 102 at a position where air is blown directly from the fans 112, 120, and 122.

  If an affirmative determination is made in step 103, control is performed to blow strong wind in step 104, and the process returns to step 101. For example, in the case where the air is blown by one fan as shown in FIG. 6B, the fan 112 is controlled to blow with a strong wind, and when the air is blown by two fans as shown in FIG. Controls the fan 120 to blow air and the fan 122 to blow strong wind.

  If a negative determination is made in step 103, it is determined in step 105 whether or not the transport drum 100 is rotating at a low speed. The low-speed rotation here is assumed to be in a standby state.

  If an affirmative determination is made in step 105, control is performed to blow strong or weak wind in step 106, and the process returns to step 101. Unlike the stop time, an air flow is also generated by the conveying drum 100. Therefore, when there is no influence on the other parts by the air blown from the fan, it is controlled to blow a strong wind, and when there is an influence, a weak wind is blown. To control.

  When blowing with a weak wind, for example, when blowing with a single fan as shown in FIG. 6B, the fan 112 is controlled to blow with a weak wind, as shown in FIG. When the air is blown by two fans, the air is blown by the fan 120 and the fan 122 is blown by a weak wind.

  If a negative determination is made in step 105, the motor operates at a speed faster than the low speed rotation, and in this case, it is assumed that an image is being formed. If an image is being formed, since there is a high possibility of affecting the ink ejection trajectory as described above, control is performed so that a slight wind is blown in Step 107, and the processing returns to Step 101.

  By blowing air in this way, temperature fluctuations can be suppressed, and erroneous detection by the above-described floating detection unit can also be suppressed.

  The processing flow of each flowchart described above is an example, and the processing order may be changed, new steps may be added, or unnecessary steps may be deleted without departing from the scope of the present invention. Needless to say, you can.

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 36 Gripper 64 Head 89 Print control part 91 Image processing part 100 Conveying drum 102 Indentation part 104 Air blower 106 Irradiation part 108 Light-receiving part 112,120,122 Fan 114 Near temperature detection part 116 Drum temperature detection part

Claims (7)

A conveyance drum for conveying the recording medium by gripping the recording medium by the grasping unit, and having a recess provided with a grasping unit for grasping the recording medium on which an image is formed;
An air blowing means for blowing air to the hollow portion;
Drum temperature detecting means for detecting the temperature of the conveying drum;
Control means for controlling the air blowing means to blow air to the recess when the temperature of the transport drum detected by the drum temperature detection means exceeds a predetermined threshold;
An image forming apparatus. It further has a near temperature detecting means for detecting a temperature in the vicinity of the transport drum,
The control means has an absolute value of a difference between a temperature of the transport drum detected by the drum temperature detection means and a temperature of the vicinity of the transport drum detected by the vicinity temperature detection means exceeding a predetermined threshold value. The image forming apparatus according to claim 1, further controlling the blowing unit so as to blow air to the hollow portion. A float detection means for detecting whether or not the recording medium floats from the surface of the transport drum by irradiating a laser beam so as to pass in the vicinity of the surface of the transport drum in the rotation axis direction of the transport drum; Have
The image forming apparatus according to claim 2, wherein the vicinity temperature detection unit detects a temperature of an optical path of the laser light as a temperature in the vicinity of the conveyance drum.   4. The image forming apparatus according to claim 1, wherein the control unit controls the air blowing unit so as to reduce an air blowing amount by the air blowing unit as the number of rotations of the transport drum increases. 5. .   When the image is formed on the recording medium, the control unit controls the blowing unit so as to reduce the amount of air blown by the blowing unit as compared with the case where the image is not formed on the recording medium. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled.   The image forming apparatus according to any one of claims 1 to 5, wherein a fan having a constant air flow rate and a fan having a variable air flow rate are provided in the air blowing unit.   The image forming apparatus according to claim 1, wherein a plurality of fans that blow air from different positions are provided in the blower unit.

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