JP4705486B2 - Fixing apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus including the same.

  A fixing device used in a continuous paper printer is a device that preheats continuous paper with a preheater, which is a hot plate, and then feeds the paper to a nip portion formed by the pressure contact between a heating roll and a pressure roll to perform heat fixing. is there. In this way, preheating the paper with the preheater and raising the paper temperature is extremely effective in stabilizing the fixing performance.

  However, since such a device preheats the paper with a preheater even during printing standby, it may cause deformation of the paper and cause wrinkles. Has been attracted as uniformly as possible, and in particular, the side edge side of the paper has been restrained.

  This is because the paper has a high air permeability value that indicates how easily air can escape from the paper (the air is less likely to escape), the thicker the paper, the more the printed part, and the higher the printing density. In the case of a laser beam printer, there are cases where printing cannot be performed due to insufficient transport force as the amount of toner attached to the transfer portion increases.

  As described above, in the conventional fixing device, the paper suction pressure at the preheater is kept constant and the paper is made as uniform as possible with the preheater even during non-printing, such as during printing and when waiting for printing, to suppress wrinkles on the preheater. The number of suction points is increased so as to be sucked in, and the paper is strongly restrained by clogging the groove on the preheater side corresponding to the position of the side edge of the paper so as to restrain the side edge of the paper to prevent air leakage. , May suppress wrinkles.

  However, when printing thick paper with a high amount of paper, the paper conveyance resistance increases, which is greater than the conveyance force due to the press contact between the heating roll and the pressure roll. Also, paper with a high air permeability value that indicates the ease of air removal from the paper, generally with thicker paper, and with a higher print density, such as more printed parts, or a laser beam printer In this case, the larger the amount of toner attached to the transfer portion, the more the conveyance force becomes insufficient and printing may not be possible.

  An object of the present invention is to obtain a fixing device capable of reducing the sheet conveyance resistance force during printing to prevent shortage of conveyance force and performing highly reliable printing even in such a case.

The present invention has a pre-heater having a heating means for adhering and pre-heating by sucking continuous paper , a heating roll having a built- in heater, and a pressure roll that is supported and detachably supported by the heating roll. , by passing the continuous sheet is transferred between the heating roller and the pressure roller through the preheater, in the fixing device of an image forming apparatus for fixing a toner image formed on the continuous paper, sucking the continuous paper Pressure control means for controlling the suction pressure sucked by the preheater so as not to cause excessive conveyance resistance depending on the paper width and paper permeability , and a seal corresponding to the maximum paper width of the continuous paper of the preheater It has the member .

  According to the present invention, in the fixing device of the continuous paper image forming apparatus, the paper suction pressure on the preheater is set at a specific suction pressure that does not generate wrinkles without being affected by the continuous paper amount and the air permeability value. Since it is designed to work consistently and stably, it can be used for thin continuous paper with a low amount of paper, to suppress paper wrinkles, and to thick paper with a high amount of paper and continuous paper with a high air permeability. On the other hand, since the conveyance resistance of continuous paper is not increased, high-density printing can be sufficiently performed even in intermittent printing such as intermittent printing or printing alignment in which printing and stopping are repeated in a short time. As a result, it is possible to realize a highly reliable fixing device and to provide a printing device that can perform a comfortable printing job or the like.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of a fixing device 1 in a fixing unit of a continuous paper laser beam printer (hereinafter referred to as a continuous paper printer) according to an embodiment of the present invention, and shows a state during printing.

  In FIG. 1, heater lamps 4 a to 4 d heat the heating roll 2. The specific temperature detector 3 attached to the end of the heating roll 2 detects that the heating roll 2 has reached a certain temperature. A plurality of thermistors 5a, 5b, and 5c that detect the surface temperature of the heating roll 2 are provided above the heating roll 2 from the non-driving side to the driving side.

  Reference numeral 6 denotes an abnormal temperature detector, which detects when the temperature of the air heated by the heating roll 2 (atmosphere temperature) exceeds a certain temperature. Reference numeral 11 denotes a preheater for preheating the continuous paper 7, which is attached to the arm 19 together with the pressure roll 10, and one end of which is rotatably supported.

  In the fixing operation, the pressure roller 10 is pressed against the heating roll 2 simultaneously with the start of printing by the rotation of the arm 19 and is controlled to leave the heating roll 2 simultaneously with the stop of printing. A groove 12 is provided in the preheater 11, and air is sucked through a suction hole 14 penetrating the groove 12 by a suction blower 17, a suction hose 15, and a pressure regulator 16 that adjusts to a specific pressure. This improves the adhesion of the continuous paper 7 to the preheating effectively.

  Further, at the position corresponding to the continuous paper maximum paper width of the preheater 11, the continuous paper is caused by the deformation of the paper due to the preheater temperature at the time of printing standby particularly by improving the adhesion at both ends of the continuous paper 7 and enhancing the restraint of the paper. A seal member 13 that suppresses paper wrinkles is provided.

  FIG. 2 is a diagram of air permeability value characteristics, sheet quantity (quality paper), and suction pressure specification characteristics regarding air suction pressure control provided with a pressure regulator in the preheater 11 for a continuous paper printer according to an embodiment of the present invention. . A one-dot chain line in the figure indicates a wrinkle generation limit line, and a two-dot chain line indicates a conveyance force shortage limit line. The solid line indicates the suction pressure by the pressure regulator according to the present invention, and the dotted line indicates the conventional suction pressure.

  As shown in FIG. 2, the pressure regulator 16 sets the pressure so that the paper wrinkles do not occur in accordance with the paper having a thin paper thickness that is likely to generate paper wrinkles, that is, the paper having a low paper continuous amount. Since the pressure is set to be relatively high, the suction pressure is further increased due to the poor air permeability in the case of paper with a high paper continuous amount with high paper thickness or a high air permeability value. In some cases, the conveyance resistance is further increased, the conveyance force is insufficient, and printing cannot be performed.

  In the present invention, a pressure regulator 16 is provided, and as shown in FIG. 2, in consideration of prevention of paper wrinkle generation on the preheater 11 when printing is stopped, the suction pressure can prevent paper wrinkles and the paper width is large. Even for paper, paper having a high amount of paper and high air permeability, a specific suction pressure that is almost constant and appropriate is set so that the conveyance resistance force in the preheater 11 does not increase so that the conveyance force does not become insufficient.

  Therefore, the above-described paper does not have an excessive suction pressure, so that there is no shortage of conveyance force, and stable and highly reliable printing is possible.

  In FIG. 1, during printing, the continuous paper 7 on which the toner image 8 formed by electrostatic transfer is placed passes over the preheater 11, so that the preheater 11 side is attracted by the above-described specific suction pressure. Therefore, the preheating effect is sufficiently increased and preheated, passes between the heating roll 2 and the pressure roll 10, is nipped and conveyed, and is heated and pressurized to be fixed on the continuous paper 7. .

  Here, the preheater 11 that heats from the back side of the paper is one-stage. However, in order to gradually increase the temperature of the paper, an upper preheater for medium temperature and a lower preheater for high temperature are provided and both arms 19 are provided. However, the present invention is not limited to this.

  In this way, the suction pressure takes into account the prevention of paper wrinkles on the preheater and is less affected by the air permeability of the printing paper, enabling stable and reliable printing. It becomes.

  As described above, according to the present invention, in the case of a continuous paper with a low sheet continuous amount, that is, a thin continuous sheet, the sheet suction pressure to the pre-heater is increased even during printing standby so that the sheet restraint property is increased and the sheet wrinkle is hardly generated. it can. Also, even in the case of thick continuous paper with a high amount of paper and paper with a high air permeability value, the paper suction pressure to the preheater does not increase, so the conveyance resistance does not increase, and the conveyance force is insufficient. It will not be impossible to print.

  As a result, a stable printing operation can be performed regardless of the characteristics of the paper, and a highly reliable operation can be performed. In addition, there is no switching of the suction pressure, and there is a remarkable effect that printing can be performed without any problem even in intermittent printing or printing alignment printing in which printing and stopping are repeated in a short time.

  FIG. 3 is a cross-sectional view of a high-speed laser beam printer equipped with a continuous paper printer fixing device according to an embodiment of the present invention.

  In FIG. 3, a photoconductor 51 is uniformly charged to a predetermined voltage by a charger 52, and an image beam transmitted from a host device (not shown) is emitted from a light source 53 to emit an irradiation beam. An electrostatic latent image is formed on the received photoreceptor 51. The electrostatic latent image is developed by a developing machine 54 using a toner made of a resin, a colorant, a charge control agent, a fluidity improver, and the like to become a visible image.

  The image visualized by the toner on the photoconductor 51 is transferred onto the continuous paper 7 by the transfer device 55. Thereafter, the charge on the surface of the photoconductor 51 is removed by the static eliminator 56, the toner remaining on the surface of the photoconductor 51 is removed by the cleaning mechanism 57, and charging, exposure, and development are repeated again. . The continuous paper 7 to which the toner image has been transferred is conveyed forward, passed through a preheater 11, is nipped and conveyed while being heated and pressurized by a heating point where the heating roll 2 and the pressure roll 10 are in contact, and the transferred toner is transferred. The image is fixed on the continuous paper 7; The fixed continuous paper 7 passes through a tension roller 58 and is sequentially discharged to a stacker 59 which is a paper receiver.

  Here, since the fixing device 1 described above is installed, when the paper is thin continuous paper (low paper continuous amount), the paper suction pressure to the preheater is increased during printing standby to enhance the paper restraint. Thus, it is possible to suppress paper wrinkles. Even when the paper is thick continuous paper (paper continuous amount is high) or paper with a high air permeability value, the paper suction pressure to the preheater is controlled to be almost constant by the pressure regulator described above. The transport resistance does not increase, and there is no possibility that printing cannot be performed due to insufficient transport force as in the prior art. A stable and reliable printing operation is possible in which printing can be performed without any problem even when intermittent printing such as intermittent printing that repeats printing and stopping in a short time or intermittent printing such as printing alignment is performed.

1 is a configuration diagram of a fixing device 1 in a fixing unit for a continuous paper printer according to an embodiment of the present invention. FIG. FIG. 5 is a characteristic diagram of sheet air permeability value and sheet continuous quantity (quality paper) and suction pressure specification regarding air suction pressure control provided with a pressure regulator in a preheater for a continuous paper printer according to an embodiment of the present invention. 1 is a cross-sectional view of a high-speed laser beam printer equipped with a continuous paper printer fixing device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fixing device, 2 ... Heating roll, 3 ... Specific temperature detector, 4a, 4b, 4c, 4d ... Heater lamp, 5a, 5b, 5c ... Thermistor, 6 ... Abnormal temperature detector, 7 ... Continuous paper, 8, DESCRIPTION OF SYMBOLS 9 ... Toner image, 10 ... Pressure roll, 11 ... Preheater, 12 ... Groove, 13 ... Sealing member, 14 ... Suction hole, 15 ... Suction hose, 16 ... Pressure regulator, 17 Suction blower, 19 ... Arm, 50 ... Continuous Paper laser beam printer, 51 ... photosensitive member, 52 ... charger, 53 ... light source, 54 ... developing device, 55 ... transfer device, 56 ... graduator, 57 ... cleaning mechanism, 58 ... tension roller 59 ... Stacker.

Claims (3)

A pre-heater having a heating means for adhering and preheating the continuous paper by sucking the continuous paper , a heating roll having a built- in heater, and a pressure roll that is supported so as to be separated from the pressure roller and rotate in pressure contact with the heating roll were transferred. by passing the continuous paper between the heating roller and the pressure roller through the preheater, in the fixing device of an image forming apparatus for fixing a toner image formed on the continuous paper,
Almost a pressure control means for controlling a constant pressure, continuous paper up of the preheater sheet width, the suction pressure for sucking so as not to excessively conveyance resistance force by the sheet air permeability value in the preheater to the suction of said continuous paper A fixing device having a seal member at a position corresponding to a sheet width .   The fixing device according to claim 1, wherein the pressure control unit includes a pressure regulator.   An image forming apparatus comprising the fixing device according to claim 1.

Images