JP2009192982A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that provides an image free from uneven gloss as a whole by enabling further large switching of a gloss range of image. <P>SOLUTION: The image forming apparatus includes an image rubbing means provided on a recording medium carrying directional downstream position of a fixing device 24 and including a gloss giving member 36 and a medium carrying member 37; a heating control means 40 controlling heating of the gloss giving member of the rubbing means; and a control means 27. When a gloss giving instruction is input by the control means, the gloss giving member is heated by the heating control means, and the image rubbing means is controlled to rub an image surface of a paper 22 with a toner image fixed by the fixing device by the gloss giving member while holding the paper 22 between the gloss giving member and the medium carrying member and carrying the paper 22 by the medium carrying member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording medium on which an image is formed after a toner image is formed on a recording medium such as a paper, a resin film, or the like, such as a copying machine, a printer, a facsimile, or a composite machine thereof, and the toner image is fixed by a fixing device. The present invention relates to an image forming apparatus in which is discharged to the outside. In particular, the present invention relates to an image forming apparatus in which the gloss of a color image can be controlled.

  In recent years, with the widespread use of color documents, color printers and copiers that form toner images using an image forming unit composed of a plurality of image carriers, developing devices, etc., or their color multifunction device MFP (Multi Function Products) Many image forming apparatuses are provided. In these image forming apparatuses, with the improvement of image quality, in recent years, a demand for high gloss is increasing in photographs, posters, and the like. On the other hand, there is also a need for a toner image with a reduced glossiness because business documents and the like have a glossy appearance and are difficult to see.

  Conventionally, there have been few image forming apparatuses that can print both such glossy images. For example, as described in Patent Document 1, a method has been proposed in which a temperature-controlled contact is pressed against a toner image after fixing, and the glossiness is controlled by the temperature.

JP 2007-4034 A

  However, with this type of method, the variable range of the glossiness is narrow and the glossiness greatly depends on the toner adhesion amount. The smaller the glossiness, the less the glossiness tends to be. When mixed on a sheet of printing, there were high and low glossy parts depending on the location, and there was a problem that unnatural images were produced in prints that require high gloss such as photos and posters. . For this reason, it has been forced to perform printing with different image forming apparatuses depending on whether a high gloss image or a low gloss image is desired.

  Accordingly, an object of the present invention is to provide an image forming apparatus in which the gloss range of an image can be switched to a greater extent and the entire image has no gloss unevenness.

  A second object of the present invention is to make it possible to raise the surface temperature of the gloss-imparting member to a certain temperature without separately providing a heating means.

  A third object of the present invention is to enable the surface temperature of the gloss-imparting member to be raised to a certain temperature efficiently by the heating means.

  A fourth object of the present invention is to stably impart gloss to an image.

  A fifth object of the present invention is to solve the problem that gloss is not imparted to an image due to foreign matter adhering to the surface of the gloss imparting member.

  A sixth object of the present invention is to provide stable gloss over the entire image surface of a recording medium.

For this reason, the invention described in claim 1 is an image forming apparatus in which a toner image is formed on a recording medium, the toner image is fixed by a fixing device, and then the recording medium on which an image has been formed is discharged to the outside.
An image rubbing means that is provided at a downstream position in the recording medium conveyance direction of the fixing device and includes a gloss imparting member and a medium conveyance member;
Heating control means for controlling the heating of the gloss imparting member of the image rubbing means;
When the gloss application command is input, the gloss control member is heated by the heating control unit, and the recording medium after the toner image is fixed by the fixing device is transferred to the gloss application member and the medium conveying member of the image rubbing unit. Control means for rubbing and rubbing the image surface of the recording medium with the gloss-imparting member while being nipped in and conveyed by the medium conveying member;
Is provided.

  When the glossing command is input to the control unit, the glossing member is heated by the heating control unit, and the recording medium after the toner image is fixed by the fixing device is transported between the glossing member of the image rubbing unit and the medium. The image forming surface of the recording medium is rubbed by the heated gloss imparting member while being nipped between the members and conveyed by the medium conveying member, and then the image-formed recording medium is discharged to the outside.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
When the gloss application command is not input, the gloss applying member of the image rubbing means is separated from the medium conveying member, and when it is input, contact / separation means that presses them is provided. To do.

  When no gloss application command is input to the control unit, the gloss applying member of the image rubbing unit and the medium conveying member are separated by the contact / separation unit, and the recording medium after toner image fixing is image rubbed by the fixing device. The image-formed recording medium is discharged to the outside without being sandwiched between the gloss imparting member and the medium conveying member. On the other hand, when a gloss application command is input, the gloss application member and the medium transport member are pressed against each other by the contact / separation means, and the recording medium after fixing the toner image is sandwiched between the gloss application member and the medium transport member, While being conveyed by the medium conveying member, the image surface of the recording medium is rubbed with the heated gloss imparting member, and then the image-formed recording medium is discharged to the outside.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect,
When the gloss imparting command is not input, the surface of the gloss imparting member of the image rubbing means contacts the image surface of the recording medium and moves at a speed that does not rub on the surface. The gloss-imparting member is speed-controlled by the control means so as to be moved at a time.

  That is, when no gloss application command is input to the control unit, the surface of the gloss applying member of the image rubbing unit contacts the image surface of the recording medium and moves at a speed that does not rub against the surface, while the gloss application command is input. The gloss imparting member is speed-controlled by the control means so that it moves at a speed of rubbing against the image surface of the recording medium.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects,
A recording medium contact surface of the gloss imparting member is configured to retain elasticity.

  When the gloss is imparted, the recording medium contact surface of the gloss imparting member rubs against the recording medium with elasticity.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects,
A surface temperature detecting means for detecting the surface temperature of the gloss imparting member; and an opening / closing means for opening and closing between the fixing device and the gloss imparting member based on a detection result of the surface temperature detecting means. It is characterized by comprising.

  When the gloss application command is input to the control unit, when the surface temperature of the gloss application member detected by the surface temperature detection unit is below a certain level, the opening / closing unit is opened and the gloss application member is heated by the heat of the fixing device. .

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects,
The heating control means includes a surface temperature detecting means for detecting a surface temperature of the gloss imparting member and a heating means for heating the gloss imparting member based on a detection result of the surface temperature detecting means. Features.

  When a gloss application command is input to the control unit, when the surface temperature of the gloss application member detected by the surface temperature detection unit is below a certain level, the gloss application member is heated by turning on the heating unit.

According to a seventh aspect of the present invention, in the image forming apparatus according to the fifth or sixth aspect,
When a gloss imparting command is input to the control means, the temperature of the gloss imparting member is higher than the lower limit temperature at which wax starts to adhere to the gloss imparting member from the toner and lower than the toner melting start temperature. It is controlled by the control means.

  When a gloss application command is input to the control unit, when the surface temperature of the gloss application member detected by the surface temperature detection unit is below a certain level, the control unit controls the temperature of the gloss application member to add gloss from the toner to the wax. Heating is performed so as to be higher than the lower limit temperature at which the toner starts to adhere to the member and lower than the toner melting start temperature.

The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 7,
The gloss applying member is provided with a wax applying means for applying a wax.
Then, the wax is applied to the gloss imparting member by the wax applying means.

The invention according to claim 9 is the image forming apparatus according to claim 8,
The present invention is characterized in that a wax amount uniformizing means for uniformizing the amount of the wax applied to the gloss imparting member by the wax applying means is provided.
Then, the amount of wax applied to the gloss imparting member by the wax applying means is made uniform by the wax amount uniformizing means.

According to a tenth aspect of the present invention, in the image forming apparatus according to the eighth or ninth aspect,
When the gloss application command is not input, the gloss applying member of the image rubbing unit and the wax applying unit are separated from each other, and when input, a wax contacting / separating unit that presses them is provided. Features.

  When the gloss application command is not input by the wax contact / separation unit, the gloss application member of the image rubbing unit and the wax application unit are separated from each other, and when the gloss application command is input, they are pressed.

The invention according to claim 11 is the image forming apparatus according to any one of claims 1 to 10,
A cleaning means for removing foreign matter adhering to the surface of the gloss imparting member is provided.
And the foreign material adhering to the surface of the gloss imparting member is removed by the cleaning means.

The invention according to claim 12 is the image forming apparatus according to any one of claims 1 to 11,
Medium conveyance speed regulation that is pressed against the medium conveyance member on the fixing device side of the gloss imparting member and conveys the recording medium to and from the medium conveyance member at the same speed as the recording medium conveyance speed of the fixing device. A member is provided.

  Then, the recording medium is conveyed at the same speed as the recording medium conveying speed of the fixing device between the medium conveying member and the medium conveying speed regulating member pressed against the medium conveying member on the fixing device side of the gloss imparting member. .

  According to the first aspect of the present invention, when a glossing command is input to the control unit, the glossing member is heated by the heating control unit, and the recording medium after image fixing by the fixing device is image-rubbed. Since the image surface of the recording medium is rubbed by the heated gloss imparting member while being sandwiched between the gloss imparting member and the medium transport member and transported by the medium transport member, the gloss control member is heated by the heating control means. Is heated and sandwiched between the gloss imparting member and the medium conveying member, thereby increasing the smoothness of the surface of the toner image on the recording medium and increasing the temperature of the gloss imparting member. By increasing the amount of exudation to increase the amount of wax on the surface of the toner image and further rubbing with a gloss imparting member, the specular reflectance on the surface of the toner image is increased, that is, an image with high glossiness can be formed. On the other hand, when no gloss application command is input, it is possible to control so that the gloss application member does not rub against the toner image so that an image having a low gloss level can be formed. Accordingly, it is possible to provide an image forming apparatus in which the gloss range of the image can be switched to a greater extent and the entire image has no gloss unevenness.

  According to the second aspect of the present invention, when no glossing command is input to the control unit, the glossing member of the image rubbing unit and the medium conveying member are separated by the contact / separation unit, and the toner image is separated by the fixing device. Since the recording medium after fixing is discharged as it is without being sandwiched between the gloss imparting member and the medium conveying member of the image rubbing means, the toner image surface smoothness on the recording medium is not increased, and recording is performed with the gloss imparting member. An image having a low glossiness can be formed without rubbing the image surface of the medium, and the gloss range of the image can be switched to a greater extent.

  According to the third aspect of the present invention, when a glossing command is not input to the control unit, the surface of the glossing member of the image rubbing unit moves at a speed that does not rub against the image surface of the recording medium. On the other hand, when the glossing command is input, the glossing member is speed-controlled by the control means so that the glossing member moves at a speed of rubbing against the image surface of the recording medium. Can be a low-gloss image and, when input, can be a high-gloss image.

  According to the fourth aspect of the present invention, when the gloss is imparted, the recording medium contact surface of the gloss imparting member is rubbed against the recording medium with elasticity, so that it adheres closely to the image surface of the recording medium and is highly glossy. It can be an image.

  According to the fifth aspect of the present invention, when the glossing command is input to the control unit, the opening / closing unit is opened to open the fixing device when the surface temperature of the glossing member detected by the surface temperature detection unit is below a certain level. Since the gloss imparting member is heated by heat, the surface temperature of the gloss imparting member can be raised to a certain temperature by the heat of the fixing device without separately providing a heating means.

  According to the sixth aspect of the present invention, when a gloss application command is input to the control unit, when the surface temperature of the gloss application member detected by the surface temperature detection unit is below a certain level, the heating unit is turned on to turn the gloss on. Since the imparting member is heated, the surface temperature of the gloss imparting member can be raised to a certain temperature efficiently by the heating means.

  According to the seventh aspect of the present invention, when a gloss application command is input to the control unit, when the surface temperature of the gloss application member detected by the surface temperature detection unit is below a certain level, the control unit controls the gloss application member. Since the temperature is heated so as to be lower than the toner melting start temperature, the toner becomes higher than the toner melting temperature, and the toner stretches like a thread or sticks to the surface of the gloss imparting member, so that the smoothness of the toner image surface is increased. On the contrary, the temperature of the gloss imparting member is heated so as to be higher than the lower limit temperature at which the wax starts to adhere to the gloss imparting member from the toner. Thus, the gloss can be stably imparted to the image without causing unevenness in the amount of applied wax or smoothing of the toner image surface.

  According to the eighth aspect of the present invention, since the wax is applied to the gloss imparting member by the wax application means, even for an image that is long in the recording medium conveyance direction, a uniform and stable gloss is imparted to the entire image. be able to.

  According to the ninth aspect of the present invention, the amount of wax applied to the gloss imparting member by the wax applying means is uniformized by the wax amount uniformizing means, so that the amount of wax applied on the gloss imparting member is uneven. A uniform and stable gloss can be imparted to the entire image without occurrence.

  According to the tenth aspect of the present invention, when no gloss application command is input by the wax contact / separation unit, the gloss applying member of the image rubbing unit and the wax applying unit are separated to apply the wax to the gloss applying member. When the gloss application command is input, the wax is applied to the gloss application member and the gloss of the image can be adjusted depending on whether the wax is applied or not.

  According to the eleventh aspect of the invention, since the foreign matter adhering to the surface of the gloss imparting member is removed by the cleaning means, the portion where the wax is not applied by the foreign matter adhering to the surface of the gloss imparting member is eliminated, and the image is displayed. The problem that gloss is not imparted can be solved.

  According to the twelfth aspect of the present invention, the recording medium is between the medium conveying speed regulating member pressed against the medium conveying member on the fixing device side of the gloss imparting member and the medium conveying member. Since it is transported at the same speed as the transport speed, it is not affected by slack or tension of the recording medium between the fixing device and the image rubbing means, and the rubbing speed of the gloss imparting member with respect to the image surface is stabilized. As a result, when a gloss application command is received, a stable gloss is imparted even at the leading and trailing edge positions of the recording medium where the rubbing speed is likely to fluctuate. Can be granted.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows an overall schematic configuration of a full-color laser printer as an example of an image forming apparatus according to the present invention.

  The illustrated full color laser printer is provided with four image forming units 10 arranged side by side. Each image forming unit 10 is provided with a photosensitive drum 12 having a diameter of 30 mm so as to be rotated clockwise at a predetermined linear velocity of 130 mm / sec. Around each photosensitive drum 12, there is a development having a charging roller 13 that rotates at the same speed as the photosensitive drum 12 as a charging device, and a developer carrier 14 that rotates at a linear speed twice that of the photosensitive drum 12. A primary cleaning member 16 for cleaning toner remaining on the surface of the photosensitive drum 12 after primary transfer, which will be described later, is provided.

The developing devices 15 of the four image forming units 10 store yellow, cyan, magenta, and black 5 μm toners from the left side, respectively, and supply the required amount of toner of the same color from four toner bottles (not shown). It has become so. Then, the toner density in the developing device 15 is made constant, the potential of the photosensitive drum 12 and the voltage applied to the developer carrier 14 are controlled, so that the toner adhesion amount on the paper becomes approximately 0.45 mg / cm ^2. It is supposed to be constant. As the black toner, not a glossy toner for a monochrome machine but a toner having a lower gloss for a color laser printer is used.

  The illustrated full-color laser printer includes an LD optical unit 17 as an exposure device that exposes the photosensitive drum 12 based on image information, an intermediate transfer belt 18 that rotates at the same speed as the linear speed of the photosensitive drum 12, and a photosensitive drum. The toner image on the intermediate transfer belt 18 is transferred to a primary transfer roller 20 as a primary transfer unit that transfers the toner image on the intermediate transfer belt 18 to the intermediate transfer belt 18 and a sheet 22 that is a recording medium conveyed from the paper supply unit 21. A secondary transfer roller 23 as a secondary transfer unit, a fixing device 24 for thermally fixing the toner image on the paper 22, a paper discharge unit 25 for discharging the image-formed paper 22 to the outside, an intermediate transfer belt 18 on the paper 22 A secondary cleaning member 26 that cleans toner remaining without secondary transfer, a control unit 27 that controls the operation of the entire printer, High voltage power supply 28 for generating a high voltage and the like applied to the capacity component is provided.

  In the illustrated example, the case where the present invention is applied to a full-color laser printer will be described. However, the present invention can be similarly applied to other printers, copiers, facsimiles, and complex machines thereof.

  By the way, the charging roller 13 is kept out of contact with the photosensitive drum 12 with an average gap of 30 μm. The difference between the DC voltage applied to the developer carrier 14 and the surface potential of the photosensitive drum 12 is −150 V in order to prevent toner from adhering to the unexposed portion of the photosensitive drum 12. A high voltage obtained by superimposing an AC voltage of 1.8 kV on a DC high voltage is applied by a high voltage power supply 28.

  The uniformly charged surface of the photosensitive drum 12 is exposed by the LD optical unit 17 in accordance with image information for each color, and an electrostatic latent image is formed. Developer on the developer carrier 14 is attached to the surface of the photosensitive drum 12 on which the electrostatic latent image is formed, and a toner image corresponding to the electrostatic latent image is obtained. The toner image formed on the photosensitive drum 12 is transferred onto the intermediate transfer belt 18 by applying a positive DC constant current to the primary transfer roller 20. Similarly, the toner image on the intermediate transfer belt 18 is transferred to the paper 22 conveyed from the paper supply unit 21 by applying a positive DC constant current to the secondary transfer roller 23. After the toner image is transferred and the image is formed, the sheet 22 is conveyed to the fixing device 24 where the toner image is fixed on the sheet 22 and then discharged to the outside by the discharge unit 25 and is discharged onto the discharge stack unit 29. Stacked.

  Here, for example, as shown in this example, the fixing device 24 includes a fixing rotor 30, a heating roller 31 incorporating a heat source, a fixing belt 32 wound around the fixing roller 30 and the heating roller 31, The pressure roller 33 is pressed against the fixing roller 30 via the fixing belt 32 to form a fixing nip therebetween. Then, when the sheet 22 after image transfer passes through the fixing nip, heat and pressure are applied, and the transferred toner image is fixed on the sheet 22.

  In the illustrated full color laser printer, an image rubbing means 35 is provided at a position downstream of the fixing device 24 in the sheet conveying direction. The image rubbing means 35 includes a gloss imparting member 36 provided so as to be in contact with the front surface (image surface) side of the paper, and a medium conveying member 37 provided so as to be in contact with the back surface side of the paper.

FIG. 2 shows a cross-sectional configuration of the gloss imparting member 36.
The gloss imparting member 36 has a roller shape in which a silicon rubber 36b having a hardness of 50 Hs and a thickness of 4 mm is provided on the outer periphery of a φ6SUS shaft 36a, and the surface of the silicon rubber 36b is coated with 30 μm of PFA (tetrafluoro-perfluoroalkyl vinyl ether resin) 36c. Is made. As described above, the gloss imparting member 36 has a configuration in which the sheet contact surface has a mirror surface or smoothness close to that using fluorine-based resin or the like and retains elasticity.

  On the other hand, the medium conveying member 37 is formed in a roller shape by providing silicon rubber having a thickness of 2 mm on the outer periphery of the φ8SUS shaft. Thereby, the friction coefficient of the surface is higher than that of the gloss imparting member 36.

FIG. 3 is a control block diagram of the full color laser printer shown in FIG.
The gloss applying member 36 and the medium conveying member 37 of the image rubbing means 35 are separated by a contact / separation means 38 shown in the figure when a gloss application command is not input to the control means 27 and pressed when input. It is controlled by the control means 27.

  Although not shown in the drawing, the contact / separation means 38, for example, a biasing member that presses the medium transport member 37 against the gloss imparting member 36, and the medium transport member 37 against the biasing force of the biasing member 36. An approach / separation cam that is separated from the center and a contact / separation motor that drives the contact / separation cam. Then, by controlling the control means 27 and driving the contact / separation cam with the contact / separation motor, when the gloss on the image on the paper 22 is to be given glossy, the medium conveying member 37 is pushed against the gloss imparting member 36 based on the biasing member. When the gloss is not applied, the medium conveying member 37 is pulled away from the gloss applying member 36.

  By the way, in this image rubbing means 35, the medium conveying member 37 is controlled by the control means 27 and driven by a driving means (not shown) so as to rotate at a linear speed substantially equal to the paper conveying speed of the fixing device 24. It has become. On the other hand, the gloss imparting member 36 is controlled by the control means 27 and driven by the same or different driving means, and is rotated at a linear speed 2% faster than the sheet conveying speed of the fixing device 24.

  Further, as shown in FIG. 3, the illustrated full color laser printer is provided with a heating control means 40 for controlling the heating of the gloss imparting member 36 of the image rubbing means 35. The heating control means 40 is, for example, a fixing device based on a surface temperature detection means 41 such as a non-contact thermistor for detecting the surface temperature of the gloss imparting member 36 as shown in FIG. 1 and the detection result of the surface temperature detection means 41. An opening / closing means 42 that opens and closes between the gloss applying member 36 and an airflow partition plate 43 that partitions the airflow from the fixing device 24.

  The opening / closing means 42 is a door-like member provided on the upper part of the fixing device 24, and when it is opened, the heat rising from the fixing device 24 is guided to the image rubbing means 35 by the airflow partition plate 43. When the gloss imparting member 36 is heated and closed, it is guided by the air flow partition plate 43 so as not to go to the image rubbing means 35, and the heating of the gloss imparting member 36 is stopped.

  Therefore, when a gloss application command is input to the control unit 27 from a print command unit (not shown), the control unit 27 controls to open the opening / closing unit 42 and heat the gloss applying member 36 by the heating control unit 40. The temperature of the gloss imparting member 36 is set to be higher than the lower limit temperature at which wax starts to adhere to the gloss imparting member 36 from the toner and lower than the toner melting start temperature.

  On the other hand, the gloss imparting member 36 and the medium transport member 37 are rotated and the medium transport member 37 is pressed against the gloss imparting member 36 by the contacting / separating means 38, and the paper 22 after the toner image is fixed by the fixing device 24 therebetween. The medium conveying member 37 is sandwiched between the gloss applying member 36 and the medium conveying member 37 of the image rubbing means 35, and the medium conveying member 37 has a larger surface friction coefficient than the gloss applying member 36. While being conveyed at the sheet conveying speed, the gloss imparting member 36 rubs the image surface of the sheet 22 due to the speed difference.

  At this time, the surface temperature detecting means 41 detects the surface temperature of the gloss applying member 36 and inputs the output value to the control means 27, so that the control means 27 controls to open and close the opening / closing means 42, thereby giving the gloss. The temperature of the member 36 is maintained so as to be higher than the lower limit temperature at which wax starts to adhere to the gloss imparting member 36 from the toner and lower than the toner melting start temperature.

  In the illustrated example, the minimum temperature at which the wax of the toner to be used is transferred to the gloss imparting member 36 is 85 ° C., and the toner melting start temperature is 105 ° C. Therefore, the target temperature is close to the toner melting start temperature at which gloss can be easily increased. 95 ° C.

  Specifically, when the temperature calculated by the control means 27 from the output value of the surface temperature detection means 41 of the gloss applying member 36 increases with time, the fixing device is at a temperature 5 ° C. lower than the target temperature 95 ° C. 24, the position is switched so that the airflow from the airflow partition plate 43 does not reach the flow passage on the gloss imparting member 36 side, and when the temperature of the gloss imparting member 36 is decreasing, the fixing is performed at a temperature 10 ° C higher than the target temperature 95 ° C. It controls so that the airflow from the apparatus 24 goes to the gloss imparting member 36 side flow path of the airflow partition plate 43.

  When the gloss application command is not input, the gloss applying member 36 and the medium conveying member 37 are separated by the contacting / separating means 38, and the sheet 22 after image fixing is heated and pressurized by the gloss applying member 36 and the medium conveying member 37. Without being rubbed, the paper is discharged as it is onto the paper discharge stack 29 on the printer through the gap between them.

  In the above-described example, when the gloss application command is not input to the control unit 27, the gloss application member 36 and the medium conveying member 37 are separated from each other, and when the gloss application command is input, the contact / separation unit 38 presses them. It was. However, without providing such contact / separation means 38, when a gloss application command is not input, the surface of the gloss application member 36 contacts the image surface of the paper 22 and moves at a speed that does not rub against it. In such a case, the gloss applying member 36 may be speed-controlled by the control means 27 so as to move at the rubbing speed.

  In the above-described example, the heating control unit 40 includes the surface temperature detecting unit 41 that detects the surface temperature of the gloss applying member 36, and the fixing device 24 and the gloss applying member 36 based on the detection result of the surface temperature detecting unit 41. And an opening / closing means 42 for opening / closing. However, a dedicated heating unit may be provided, and the gloss imparting member 36 may be heated by the dedicated heating unit or the heat of the fixing device 24 based on the detection result of the surface temperature detection unit 41.

  In FIG. 4, when the gloss imparting member 36 and the medium conveying member 37 are separated from each other, the target temperatures of the gloss imparting member 36 are set to 55 ° C., 85 ° C., 95 ° C., 105 ° C., and 120 ° C. In this case, the glossiness comparison data of a solid image of one color of toner and a solid image of two colors superimposed are shown. Here, glossy coated paper was used as the recording medium, and the solid image formed thereon was a square image with a side of 30 mm.

  As can be seen from this figure, compared to the image in which the gloss imparting member 36 and the medium conveying member 37 are separated from each other, the glossiness is higher in all the images in which the gloss imparting command is received and pressed. In addition, as the target temperature of the gloss imparting member 36 is higher, the glossiness is higher.

  However, when the target temperature is 105 ° C. and 120 ° C., especially when the two-color solid image at 120 ° C. is used, a streak-like image disturbance occurs partially in the paper tip direction of the toner adhesion portion, and the gloss is As a result, the toner was adhered to the surface of the gloss imparting member 36. When the control target temperature is 105 ° C., the toner melting start temperature may temporarily exceed 105 ° C. due to temperature variation, and when the control target temperature is 120 ° C., the toner melting start temperature is always exceeded. This is because. As a result, the toner layer thermally fixed by the fixing device 24 is melted again and becomes easy to flow, so that the toner moves by rubbing against the gloss imparting member 36.

  FIG. 5 shows the result of measuring the surface roughness of the toner adhering portion of the image with an optical non-contact surface roughness meter. The vertical axis displays the height in the direction perpendicular to the paper surface by shifting it under four conditions for easy viewing, and the horizontal axis represents the position in the direction perpendicular to the paper transport direction in the paper surface. The unevenness is shown.

  As can be seen from FIG. 5, the convex portion of the adhering toner is flat compared to the image when the glossing command is received and when the glossing command is not received, and the area of the flat portion is the glossing member 36. As the temperature increases, it spreads and shows a saturation tendency on the high temperature side. The formation of a flat surface on the surface of the adhered toner is one of the causes for increasing the glossiness. However, the glossiness is even higher at a temperature higher than the temperature at which the flat surface area of the adhered toner surface is saturated on the high temperature side, and cannot be explained only by the adhered toner surface shape.

  As a result of further investigation of the cause, it has been found that the amount of wax added to the toner increases as the temperature increases on the outermost surface of the adhered toner and the surface of the gloss imparting member 36. This is presumably because when the temperature of the gloss imparting member 36 is high, the wax contained in the adhered toner on the paper 22 oozes out to the surface by increasing the temperature of the gloss imparting member 36.

  From the above, according to the image forming apparatus of the present invention, the gloss can be increased by the two effects of the effect of widening the smooth portion of the surface of the adhered toner and the effect of increasing the amount of wax on the surface of the adhered toner. Was confirmed.

  FIG. 6 shows a cross-sectional configuration of the gloss imparting member 45 whose recording medium contact surface does not have elasticity. The gloss imparting member 45 in this example has the same outer diameter as that of the gloss imparting member 36 shown in FIG. 2, and a fluorine-based tube 45b is bonded around a φ14 SUS shaft 45a.

  When the gloss imparting member 45 as shown in this example is used instead of the gloss imparting member 36 shown in FIG. 2, the gloss of the image is not only increased on one side with a slight twist, but the image on the side where the gloss can be increased. As a result, gloss unevenness was scattered in the area. As a result of confirming this cause, the parallelism between the gloss imparting member 45 and the medium conveying means 37 is shifted by about 0.3 mm, and there is an unevenness of about 0.06 mm formed on the surface of the gloss imparting member 45, as shown in FIG. In the gloss imparting member 45, the surface cannot be in close contact with the recording medium, and a portion that is rubbed and a portion that is floating are generated, resulting in a difference in gloss.

  As described above, in the image forming apparatus according to the present invention, if the gloss imparting member is not elastic, not only the mechanical accuracy has to be increased in order to increase the parallelism between the gloss imparting member 45 and the medium conveying means 37, but also the gloss imparting member. It has been found that unevenness is likely to occur, and sufficient effects of the present invention cannot be obtained.

  By the way, when a solid image having a length of 180 mm is printed in the recording medium conveyance direction with the image forming apparatus shown in FIG. 1, the gloss may be lowered toward the rear end of the image. As a result of investigating this cause, the glossiness decreases with the number of rounds of the gloss imparting member 36 from the front end of the image in a long solid image, and the amount of wax adhering to the surface of the gloss imparting member 36 comes into contact with the toner each time. It was confirmed that the amount of wax on the adhered toner surface of the images of the second and third rounds decreased compared to the first round of the gloss imparting member 36.

FIG. 7 shows a configuration of another example of the present invention in which such a defect in the image forming apparatus shown in FIG. 1 is eliminated.
In this example, for example, in addition to the configuration of the image forming apparatus of FIG. 1, a plate-like wax 50, a wax application roller 51 that is a wax application unit that applies the wax 50 to the gloss imparting member 36, and a wax application roller A wax amount equalizing means 52 for equalizing the amount of wax applied to the gloss imparting member 36 by 51 is provided.

  As the wax 50, carnauba wax, aliphatic hydrocarbon wax, synthetic hydrocarbon wax, ester wax, urethane resin wax, acrylic resin wax, olefin wax, fatty acid amide wax, paraffin wax and the like can be used. Here, an example using an acrylic resin wax will be described.

  The wax application roller 51 is made of a SUS φ8 metal roller, rotates in contact with the wax 50 and the gloss imparting member 36, and applies the wax to the surface of the gloss imparting member 36. The wax amount uniformizing means 52 is formed of a rubber blade, and is downstream of the position where the wax application roller 51 contacts the wax 50 with respect to the rotation direction of the wax application roller 51. At the upstream side of the contact position, the wax application roller 51 is provided so as to contact the belly.

  In the image forming apparatus of this example, the rotational speed of a motor (not shown) that rotates the gloss imparting member 36 can be switched, and when the gloss command is received together with the print command from the print command means, the linear speed of the medium transport means 37 is set. When the gloss imparting member 36 is rubbed against the toner on the paper 22 by increasing the linear velocity of the gloss imparting member 36 and the gloss imparting command is not received, the linear speed of the gloss imparting member 36 is set to the medium conveying means. 37, the gloss imparting member 36 and the toner on the paper 22 are hardly rubbed at the same linear velocity. Reference numeral 41 in the figure denotes a surface temperature detecting means similar to the previous example.

  As a result, in this example, as a result of printing a solid image of 180 mm in the recording medium conveyance direction, the gloss can be made substantially constant in the number of circulations 1 to 4 from the image front end of the gloss imparting member 36, and the image forming apparatus shown in FIG. The glossiness could be further stabilized even for an image longer in the recording medium conveyance direction. Further, it is possible to provide an image forming apparatus that switches between gloss differences based on ON / OFF of gloss application from the print command means, and that can perform printing with high gloss and less gloss unevenness when gloss application is ON.

FIG. 8 shows the configuration of still another example of the image forming apparatus according to the present invention.
Reference numeral 51 in the drawing is made of a SUS8 metal roller of φ8, as in the example shown in FIG. 7, rotates in contact with a plate-like wax (not shown) and the gloss imparting member 36, and the wax is supplied to the gloss imparting member 36. It is a wax application roller which is a wax application means for applying to the surface. In this example, when a gloss application command is not input by a wax contact / separation unit (not shown), it is input without being applied to the gloss application member 36 away from the gloss application member 36 of the image rubbing unit 35. In some cases, the gloss is applied to the gloss imparting member 36 while being in pressure contact with the gloss imparting member 36, and the gloss of the image can be adjusted depending on whether the wax is applied or not.

  Reference numeral 53 in the drawing denotes a cleaning unit that removes foreign matter adhering to the surface of the gloss imparting member 36. The felt is affixed to the base so that the felt surface in contact with the gloss imparting member 36 has the same curvature as the surface of the gloss imparting member 36. Then, the rotation of the gloss imparting member 36 cleans the surface to remove the foreign matter adhering to the surface of the gloss imparting member 36, and a portion where the wax is not applied by the foreign matter adhering to the surface of the gloss imparting member 36 occurs. While solving the problem that the image is not glossy, the wax on the glossing member 36 is made uniform.

  In this example, an example in which carnauba wax is used as the wax material applied to the gloss imparting means 36 will be described. The wax molded into a plate shape is pressed, supplied to the surface of the wax application roller 51, applied to the gloss imparting member 36, and made uniform by the cleaning means 53 in contact with the gloss imparting member 36.

  In addition, the rotational speed of a motor (not shown) that rotates the gloss applying means 36 can be switched, and when the gloss giving command is received together with the print command from the print command means, the gloss applying member 36 with respect to the linear speed of the medium transport means 37. When the gloss imparting means 36 rubs the toner on the recording medium and does not receive the gloss imparting command, the linear speed of the gloss imparting member 36 is set to the same linear speed as that of the medium conveying means 37. The gloss applying means 36 is hardly rubbed against the toner on the recording medium.

  Further, in the gloss imparting member 36 of this example, a roller having a 3 mm-thick silicon rubber attached to the outer periphery of a pipe shaft incorporating a heater as a heating means and a PTFE (tetrafluoroethylene resin) coated surface is used. . The temperature of the gloss imparting member 36 is detected by the surface temperature detecting means 41, and the heater in the pipe shaft of the gloss imparting member 36 is ON / OFF controlled to control the temperature.

  Then, under both conditions of glossing ON and OFF, the wax is applied to the gloss imparting member 36 even if the whole surface solid image is printed after continuously printing the belt-shaped solid image of 180 mm in the recording medium conveyance direction and 30 mm in the width direction. By applying, gloss unevenness due to image history does not occur, and it has been confirmed that a difference in gloss can be made depending on whether or not the gloss imparting member 36 and the recording medium are rubbed. As a result, it is possible to provide an image forming apparatus that switches between gloss differences based on the gloss application ON / OFF from the print command means, and that can perform printing with high gloss and less gloss unevenness when gloss application is ON.

FIG. 9 shows an overall schematic configuration of a full-color laser printer which is still another example of the present invention.
In the example shown in FIG. 9, in FIG. 8, in the rotational direction of the gloss applying member 36, the wax application roller 51 located immediately downstream of the cleaning unit 53 is moved to a position immediately upstream of the cleaning unit 53 to give gloss. It is pressed against the member 36.

  The medium that is pressed against the medium conveying member 37 on the fixing device 24 side of the gloss imparting member 36 and conveys the recording medium to and from the medium conveying member 37 at the same speed as the recording medium conveying speed of the fixing device 24. A conveyance speed regulating member 54 is provided. The medium conveyance speed regulating member 54 is a roller in which a silicon rubber having a thickness of 3 mm is attached to the outer periphery of a φ8 SUS shaft. The medium conveyance speed regulating member 54 has a larger coefficient of friction than the gloss imparting member 36, and the recording medium conveyance of the fixing device 24. It rotates at almost the same linear velocity as the speed. As described above, since the friction coefficient is higher than the friction coefficient of the gloss imparting member 36, the linear speed of the recording medium is determined by the linear speed of the medium transport speed regulating means 54, and the toner image on the recording medium immediately after fixing is used as the gloss imparting member. 36 allows rubbing.

  9, parts corresponding to those in FIG. 1 are denoted by the same reference numerals as those used in FIG. 1, and repeated description is omitted.

  Therefore, the sheet 22 as the recording medium is recorded between the medium conveying member 37 and the medium conveying speed regulating member 54 pressed against the medium conveying member 37 on the fixing device 24 side of the gloss imparting member 36. Since the sheet is conveyed at the same speed as the medium conveying speed, the rubbing speed of the gloss imparting member 36 with respect to the image surface is not affected by the slack or tension of the paper 22 between the fixing device 24 and the image rubbing means 35. Can be stabilized. As a result, when a gloss application command is received, a stable gloss is imparted even at the leading and trailing edge positions of the paper 22 where the rubbing speed is likely to change, and a stable gloss is imparted to the entire image surface of the paper 22. can do.

FIG. 10 shows a cross-sectional configuration of the gloss imparting member 36 used in the full color laser printer shown in FIG.
In this example, as the gloss imparting member 36, a roller is used in which a silicon rubber 36e having a hardness of 50Hs and a thickness of 4 mm is provided on the outer periphery of a φ8 SUS shaft 36d, and the surface thereof is coated with 30 μm of PFA 36f. As the medium transport means 37, a roller is used in which a silicon rubber having a thickness of 4 mm is attached to a φ20 aluminum pipe shaft.

  As shown in FIG. 9, the heating control means 40 includes a surface temperature detection means 41 such as a non-contact thermistor that detects the surface temperature of the gloss imparting member 36, and the surface temperature detection means 41 as shown in FIG. 1. On the basis of the detection result, an opening / closing means 42 that opens and closes between the fixing device 24 and the gloss imparting member 36 and an airflow partition plate 43 that partitions the airflow from the fixing device 24 are configured. When a gloss application command is input to the control unit 27 and the surface temperature of the gloss application member 36 detected by the surface temperature detection unit 41 is below a certain level, the control unit 27 uses the heat of the fixing device 24. The gloss imparting member 36 is heated so that the temperature is higher than the lower limit temperature at which wax starts to adhere to the gloss imparting member from the toner and lower than the toner melting start temperature.

  In FIG. 11, in this example, when the gloss imparting member 36 and the medium conveying member 37 are separated from each other, the target temperatures of the gloss imparting member 36 are 55 ° C., 85 ° C., 95 ° C., 105 ° C. The gloss level comparison data of a solid image of one color of toner and a solid image of two colors superimposed when set to 120 ° C. are shown. Also here, glossy coated paper was used as the recording medium, and the solid image formed thereon was a square image with a side of 30 mm.

  FIG. 12 shows the result of measuring the surface roughness of the toner adhering portion of the image with an optical non-contact surface roughness meter in this example. As in FIG. 5, the vertical axis represents the height in the direction perpendicular to the paper surface by shifting it under four conditions for easy viewing, and the horizontal axis represents the position in the direction perpendicular to the paper transport direction in the paper surface. As a result, irregularities on the surface of the toner image are shown.

  As described above, it has been confirmed that the image forming apparatus shown in FIG. 9 can also increase the gloss by the two effects of widening the smooth portion of the adhered toner surface and the effect of applying the wax to the toner image surface. It was done. The non-glossy image has an unnatural image with low gloss in the area where the toner adhesion amount is not large, whereas the glossy image in this example is glossy even in the area where the toner adhesion amount is small. Therefore, a more natural image can be obtained over the entire image area.

1 is an overall schematic configuration diagram of a full-color laser printer shown as an example of an image forming apparatus according to the present invention. It is a cross-sectional block diagram of the gloss imparting member used with the full color laser printer. It is a control block diagram in the same printer. In the printer, when the gloss imparting member and the medium conveying member are separated from each other, and when the target temperature of the gloss imparting member is set to 55 ° C., 85 ° C., 95 ° C., 105 ° C., and 120 ° C. by pressing them, FIG. 6 is a diagram illustrating glossiness comparison data of a solid image of one color of toner and a solid image of two colors superimposed. It is a figure which shows the result of having measured the surface roughness of the toner adhesion part of an image with the optical non-contact surface roughness meter. FIG. 3 is a cross-sectional configuration diagram of a gloss-imparting member whose recording medium contact surface does not have elasticity. It is a figure which shows the structure of the other example of this invention which eliminated the fault in the laser printer shown in FIG. It is a figure which shows the structure of the other example of the image forming apparatus by this invention. It is a whole schematic block diagram of the full-color laser printer which is further another example of this invention. FIG. 10 is a cross-sectional configuration diagram of a gloss imparting member used in the full color laser printer shown in FIG. 9. In the example shown in FIG. 9, when the gloss imparting member and the medium transport member are separated from each other, the target temperatures of the gloss imparting member are set to 55 ° C., 85 ° C., 95 ° C., 105 ° C., and 120 ° C. by pressing them. FIG. 6 is a diagram showing glossiness comparison data of a solid image of one color of toner and a solid image of two colors superimposed in the case. In the example shown in FIG. 9, it is a figure which shows the result of having measured the surface roughness of the toner adhesion part of an image with the optical non-contact surface roughness meter.

Explanation of symbols

22 Paper (Recording medium)
24 Fixing Device 25 Discharge Unit 27 Control Unit 35 Image Rubbing Unit 36 Gloss Applying Member 36b Silicon Rubber 37 Medium Conveying Unit 38 Contacting / Separating Unit 40 Heating Control Unit 41 Surface Temperature Detection Unit 42 Opening / Closing Unit 43 Airflow Partition Plate 50 Wax 51 Wax Application Roller (wax application means)
52 Wax amount uniformizing means 53 Cleaning means 54 Medium transport speed regulating member

Claims (12)

In an image forming apparatus in which a toner image is formed on a recording medium and the toner image is fixed by a fixing device, and then an image-formed recording medium is discharged to the outside.
An image rubbing means that is provided at a downstream position in the recording medium conveyance direction of the fixing device and includes a gloss applying member and a medium conveyance member;
Heating control means for controlling the heating of the gloss imparting member of the image rubbing means;
When the gloss application command is input, the gloss control member is heated by the heating control unit, and the recording medium after the toner image is fixed by the fixing device is transferred to the gloss application member and the medium conveying member of the image rubbing unit. Control means for rubbing and rubbing the image surface of the recording medium with the gloss-imparting member while being nipped in and conveyed by the medium conveying member;
An image forming apparatus comprising: The image forming apparatus according to claim 1,
When the gloss application command is not input, the gloss applying member of the image rubbing means is separated from the medium conveying member, and when it is input, contact / separation means that presses them is provided. Image forming apparatus. The image forming apparatus according to claim 1,
When the gloss imparting command is not input, the surface of the gloss imparting member of the image rubbing means contacts the image surface of the recording medium and moves at a speed that does not rub on the surface. The gloss forming member is speed-controlled by the control means so as to move in the image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the gloss-imparting member has a configuration in which a recording medium contact surface has elasticity. 5. The image forming apparatus according to claim 1, wherein:
A surface temperature detecting means for detecting the surface temperature of the gloss imparting member; and an opening / closing means for opening and closing between the fixing device and the gloss imparting member based on a detection result of the surface temperature detecting means. An image forming apparatus comprising: 5. The image forming apparatus according to claim 1, wherein:
The heating control means includes a surface temperature detecting means for detecting a surface temperature of the gloss imparting member and a heating means for heating the gloss imparting member based on a detection result of the surface temperature detecting means. An image forming apparatus. The image forming apparatus according to claim 5 or 6,
When a gloss imparting command is input to the control means, the temperature of the gloss imparting member is higher than the lower limit temperature at which wax starts to adhere to the gloss imparting member from the toner and lower than the toner melting start temperature. An image forming apparatus controlled by the control means. The image forming apparatus according to any one of claims 1 to 7,
An image forming apparatus comprising: a wax applying unit that applies a wax to the gloss imparting member. The image forming apparatus according to claim 8.
An image forming apparatus comprising: a wax amount uniformizing unit that uniformizes an amount of wax applied to the gloss imparting member by the wax applying unit. The image forming apparatus according to claim 8 or 9, wherein
When the gloss application command is not input, the gloss applying member of the image rubbing unit and the wax applying unit are separated from each other, and when input, a wax contacting / separating unit that presses them is provided. An image forming apparatus. The image forming apparatus according to claim 1,
An image forming apparatus comprising: a cleaning unit that removes foreign matter adhering to the surface of the gloss imparting member. The image forming apparatus according to claim 1,
Medium conveyance speed regulation that is pressed against the medium conveyance member on the fixing device side of the gloss imparting member and conveys the recording medium to and from the medium conveyance member at the same speed as the recording medium conveyance speed of the fixing device. An image forming apparatus comprising a member.

Images