JP2011085785A - Fixing device and image forming apparatus using the same - Google Patents

Abstract

A fixing device having a plurality of laser elements in which the frequency of use of each laser element can be made uniform and the rate of deterioration is minimized.
A fixing device includes a laser head L1 that irradiates a recording medium to be conveyed with laser light to heat and fix an unfixed toner image on the recording medium. The laser head L1 includes a plurality of laser elements 11, A plurality of convex lenses 8, a lens holder 7 for fixing the convex lenses 8, a silicon substrate 3 with electrodes for electrically connecting the plurality of laser elements, a light receiving element for receiving light from the laser element 11, and a signal from the light receiving element And a heat radiating plate 9 for radiating heat generated from the plurality of laser elements, and the plurality of laser elements 11 that emit the laser light are transported by a recording medium. A plurality of laser elements 11 which are arranged in a row in a direction orthogonal to the direction in which they are used and are commonly used for recording media of different sizes, and a plurality of laser elements 11 which are not commonly used. Are arranged at different dense index than the element 11, operation is differently controlled.
[Selection] Figure 3

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile machine. More specifically, the present invention relates to fixing an unfixed image formed on a recording member by irradiating a laser beam with toner. The present invention relates to a fixing device to be performed and an image forming apparatus having the same.

  An electrophotographic image forming apparatus (for example, a printer) includes a fixing device that fixes a toner image formed on a recording member (recording paper or paper) onto the paper by heat melting. As an example of this fixing device, as disclosed in Patent Document 1, a roller-pair type fixing device including a fixing roller and a pressure roller is known.

  The fixing roller is a roller member in which an elastic layer is formed on the surface of a metallic hollow core metal such as aluminum, and a halogen lamp is arranged as a heat source inside the core metal. The temperature control device controls the temperature of the surface of the fixing roller by performing on / off control of the halogen lamp based on a signal output from a temperature detecting means provided on the surface of the fixing roller.

  The pressure roller is a roller member in which a heat-resistant elastic layer such as silicon rubber is provided as a coating layer on a cored bar. The pressure roller is pressed against the peripheral surface of the fixing roller, and a nip region is formed between the fixing roller and the pressure roller by elastic deformation of the elastic layer of the pressure roller.

  In the above-described configuration, the fixing device sandwiches the paper on which the unfixed toner image is formed in the nip region between the fixing roller and the pressure roller, and conveys the paper by rotating both the rollers and fixes the fixing paper. The toner image on the paper is melted and fixed on the paper by the heat of the roller peripheral surface.

  However, in the conventional roller pair system, after the power is turned on in the morning, the fixing roller and the pressure roller are in a greenhouse state, so that it is necessary to raise the temperature to a predetermined temperature after the power is turned on. Further, in the atmospheric state where the copying operation is not performed, the roller surface needs to be maintained at a predetermined temperature. Therefore, even when the copying operation is not performed, the pressure must be constantly applied, and this is wasteful in addition to the copying operation. Consumes a lot of energy.

  Therefore, as a method for efficiently fixing only toner without consuming wasteful energy, a fixing device for fixing using a laser beam as disclosed in Patent Document 2 has been proposed.

  According to Patent Document 2, the toner is heated using a plurality of laser beams, so that the fixing performance that is insufficient with a single laser beam is improved by using a plurality of laser beams. This describes that it is possible to use a low-power and inexpensive laser light source device, and that the entire device can also have a simplified configuration.

Japanese Patent Laid-Open No. 11-38802 JP-A-7-191560

  However, although the plurality of laser elements of Patent Document 2 are simply arranged at equal intervals, no measures have been taken to minimize the deterioration of the laser elements corresponding to various sizes of paper. The laser elements that are used in common for different sizes of papers have a problem that they are quickly damaged due to their high frequency of use, making laser irradiation impossible and shortening the product life as a fixing device.

  The present invention has been made in view of the above circumstances, and when fixing sheets of different sizes, a plurality of laser elements in a commonly used area are replaced with a plurality of laser elements in a non-commonly used area. It is arranged more densely than the laser elements, and by changing the output or lighting time of each laser element differently for each region, the operation of the laser elements can be reduced, the deterioration of the laser elements can be minimized, and the lifetime It is an object of the present invention to provide a fixing device having a long laser element and an image forming apparatus including the same.

  In order to solve the above-described problems, each configuration of the fixing device according to the present invention and the image forming apparatus including the same is as follows.

  The fixing device of the present invention is a fixing device including laser irradiation means for irradiating a recording medium to be conveyed with laser light to heat and fix an unfixed toner image on the recording medium, wherein the laser irradiation means includes the laser light. Are arranged in a row in a direction orthogonal to the direction in which the recording medium is conveyed, and are used in common for the recording media having different sizes The plurality of laser elements that are not used in common are arranged at a different density and are controlled to operate differently.

  The fixing device may be configured such that a pitch of the plurality of laser elements used in common for a recording medium having a predetermined size and a recording medium having a size smaller than the predetermined size is a recording medium having a predetermined size. Only the pitch of the plurality of laser elements used only is different.

  In the fixing device, the power consumption of each of the plurality of laser elements commonly used for a recording medium of a predetermined size and a recording medium of a size smaller than the predetermined size is a predetermined size. The power consumption of each of the plurality of laser elements used only for a recording medium is different.

  In addition, the fixing device is configured such that the lighting time of the plurality of laser elements used in common for a recording medium having a predetermined size and a recording medium having a size smaller than the predetermined size is a recording medium having a predetermined size. It is controlled so as to be different from the lighting time of the plurality of laser elements used only for the laser beam.

  The fixing device may be configured such that the number of rows of the plurality of laser elements commonly used for a recording medium having a predetermined size and a recording medium having a size smaller than the predetermined size is a recording having a predetermined size. It is different from the number of rows of the plurality of laser elements used only for the medium.

  The image forming apparatus of the present invention includes an optical scanning device that deflects and scans laser light, a photosensitive drum on which an electrostatic latent image is formed by irradiation of the laser light from the optical scanning device, and a photosensitive drum. A developing means for developing the developer by attaching a developer to the formed electrostatic latent image; and a transfer means for transferring the developer attached by the developing means to a recording medium. It is characterized by using.

  According to the present invention, there is provided a fixing device including laser irradiation means for irradiating a recording medium to be conveyed with laser light to heat and fix an unfixed toner image on the recording medium, wherein the laser irradiation means The plurality of laser elements to be emitted are arranged in a row in a direction orthogonal to the direction in which the recording medium is conveyed, and the plurality of laser elements commonly used for the recording mediums having different sizes The multiple laser elements that are not used in common are arranged at a different density and are controlled to operate differently, so that the frequency of use of each laser element can be made uniform, and the rate of deterioration is minimized. An excellent effect of realizing a fixing device having a plurality of suppressed laser elements can be obtained.

  According to the present invention, the fixing device has a power consumption of each of the plurality of laser elements commonly used for a recording medium having a predetermined size and a recording medium having a size smaller than the predetermined size, The power consumption of a plurality of laser elements in an area commonly used when fixing sheets of different sizes by being different from the power consumption of each of the plurality of laser elements used only for a recording medium of a predetermined size Can be achieved, and an excellent effect of minimizing the deterioration of the laser element can be obtained.

  According to the present invention, the fixing device is configured such that a pitch of the plurality of laser elements commonly used for a recording medium having a predetermined size and a recording medium having a size smaller than the predetermined size is a predetermined size. When fixing papers of different sizes, the plurality of laser elements in a commonly used area are different from the pitch of the plurality of laser elements used only in the recording medium of It can be arranged more densely than a plurality of laser elements, and by changing the lighting time and output of each laser element differently for each region, it is possible to achieve an excellent effect that deterioration of the laser elements can be minimized. .

  According to the present invention, the fixing device has a predetermined lighting time of the plurality of laser elements used in common for a recording medium having a predetermined size and a recording medium having a size smaller than the predetermined size. By controlling so as to be different from the lighting times of the plurality of laser elements used only for the recording medium of the size, when fixing sheets of different sizes, The lighting time can be made shorter than the lighting times of a plurality of laser elements in a region not commonly used, and an excellent effect can be obtained in that deterioration of frequently used laser elements can be minimized.

  According to the present invention, the fixing device is configured such that the number of rows of the plurality of laser elements commonly used for a recording medium having a predetermined size and a recording medium having a size smaller than the predetermined size is predetermined. By differing from the number of rows of the plurality of laser elements used only for the recording medium of the size, the net total lighting time of each laser element can be made uniform, and the deterioration of the laser elements is minimized. An excellent effect of being able to be suppressed can be achieved.

  According to the present invention, an image forming apparatus of the present invention includes an optical scanning device that deflects and scans laser light, a photosensitive drum on which an electrostatic latent image is formed by irradiation of the laser light by the optical scanning device, A developing unit that develops the developer by attaching a developer to the electrostatic latent image formed on the photosensitive drum; and a transfer unit that transfers the developer attached by the developing unit to a recording medium. By using the fixing device, it is possible to achieve an excellent effect that image formation without fixing unevenness can be performed.

1 is a schematic diagram illustrating a configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention. 1 is a schematic view of a fixing device according to an embodiment of the present invention. It is a front view of the laser head part concerning a 1st embodiment of the present invention. It is a side view of the laser head part concerning a 1st embodiment of the present invention. 2 is a block diagram of a control unit of the image forming apparatus according to the present embodiment. FIG. It is a front view of the laser head part concerning the 2nd Embodiment of this invention. It is a top view of the laser head part which concerns on the 2nd Embodiment of this invention.

Next, an image forming apparatus including the fixing device according to the embodiment of the present invention will be described. In this embodiment, the image forming apparatus is applied to a color multifunction peripheral.
<First Embodiment>

  FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus 100 including a fixing device according to an embodiment of the present invention. FIG. 2 is a schematic view of the fixing device according to the embodiment of the present invention. FIG. 3 is a front view of the laser head unit according to the first embodiment of the present invention. FIG. 4 is a side view of the laser dead portion according to the first embodiment of the present invention. FIG. 5 is a block diagram of a control unit of the image forming apparatus according to the present embodiment.

  As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment has multiple colors and recording colors (sheets) for a recording member (paper) based on a scanned original image or image data transmitted from the outside via a network or the like. A monochrome image is formed.

  The image forming apparatus 100 according to this embodiment includes an optical system unit E, four sets of visible image forming units 21a to 21d, an intermediate transfer belt 12, a secondary transfer unit 14, a fixing device 1, a scanner image reading unit (not shown). ), An internal paper feed unit 16 and a manual paper feed tray 17.

  The image data of the color image handled in the image forming apparatus 100 according to the present embodiment is image data corresponding to the four hues of black (K), cyan (C), magenta (M), and yellow (Y). The visible image forming units 21a to 21d are used to form visible images. This corresponds to a color image using each color. Accordingly, the photosensitive drum 101 (101a to 101d), the charging unit 103 (103a to 103d), the developing unit 102 (102a to 102d), the cleaning unit 104 (104a to 104d), and the primary transfer unit 13 (13a to 13d) are provided. Four are provided so as to form four types of latent images corresponding to the respective colors.

  Next, each component related to the image forming apparatus 100 according to the present embodiment will be sequentially described.

  A scanner image reading apparatus (not shown) is arranged on the upper part of the image forming apparatus 100 and reads an image of a document. Further, the image processing unit 25 in the control unit 24 converts the read document image into an appropriate electrical signal and forms image data of each color.

  The optical system unit E (exposure unit) includes a plurality of light sources 41 that emit laser light according to the read image data of each color, and a polygon that scans the laser light by reflecting and deflecting the laser light emitted from the light source 41. A mirror (not shown), a plurality of lenses (not shown) that are optical components for converging the laser light into an elongated line image, a plurality of reflecting mirrors 42, and detecting the laser light and outputting a horizontal synchronizing signal A BD sensor (not shown) or the like.

  The optical system unit E exposes the outer peripheral surface of the photosensitive drum 101 uniformly charged by the charging unit 103 in accordance with the input image data, thereby converting the input image data onto the outer peripheral surface of the photosensitive drum 101. A corresponding electrostatic latent image is formed.

    In the light source 41 of the optical system unit E, a laser diode is used. Instead, a writing head in which light emitting elements such as EL (Electro Luminescence) and LED (Light Emitting Diode) are arranged in an array is used. May be.

  The visible image forming units 21a to 21d have the same configuration. For example, the black visible image forming unit 21a includes a photosensitive drum 101a, a charging unit 103a, a developing unit 102a, a cleaning unit 104a, a primary transfer unit 13a, and the like.

  The visible image forming units 21 a to 21 d are arranged in a line in the moving direction (sub-scanning direction) of the intermediate transfer belt 12. In the codes a to d, a corresponds to black, b corresponds to cyan, c corresponds to magenta, d corresponds to yellow, and the four visible image forming units are distinguished by the above-described means distinguished by these codes. Is configured.

  The photosensitive drum 101 is a substantially cylindrical image carrier disposed above the optical system unit E. The photosensitive drum 101 is controlled to rotate in a predetermined direction (sub-scanning direction) by a driving unit and a control unit (not shown).

  The photosensitive drum 101 is configured by forming a photoconductive layer on a base material. For example, a metal drum made of aluminum or the like is used as a base material, and a photoconductive layer such as amorphous silicon (a-Si), selenium (Se), or an organic photo semiconductor (OPC) is formed in a thin film shape on the outer peripheral surface thereof. ing. Note that the configuration of the photosensitive drum 101 is not limited to the above-described configuration.

  The charging unit 103a is charging means for uniformly charging the outer peripheral surface of the photosensitive drum 101a to a predetermined potential. The charging unit 103a is disposed so as to be in contact with the outer peripheral surface of the photosensitive drum 101a on the opposite side of the position where the primary transfer unit 13a is disposed with the photosensitive drum 101a interposed therebetween. In this embodiment, a charge type charger is used as the charging unit 103a. However, a roller type charging unit and a brush type charging unit may be used instead of the charge type charger.

  The developing unit 102a supplies toner to the surface of the photosensitive drum 101a on which the electrostatic latent image is formed, and develops the electrostatic latent image into a toner image. Each of the developing units 102a to 102d contains toner of each hue of black, cyan, magenta, and yellow. Each of the developing units 102a to 102d makes the formed electrostatic latent image of each hue noticeable as a toner image of each corresponding hue.

  The cleaning unit 104 (104a to 104d) removes and collects toner remaining on the surface of the photosensitive drum 101 after development and image transfer with a lubricant or the like.

  The primary transfer units 13 a to 13 d transfer the toner images carried on the surfaces of the photosensitive drums 101 a to 101 d onto the intermediate transfer belt 12. Each primary transfer unit 13a to 13d is applied with a primary transfer bias having a polarity opposite to the charging polarity of the toner by constant voltage control. By this application, the toner images of the respective colors formed on the photosensitive drums 101a to 101d are sequentially transferred onto the outer peripheral surface of the intermediate transfer belt 12, and a full color toner image is formed on the outer peripheral surface of the intermediate transfer belt 12. The

  The primary transfer units 13 a to 13 d are pressed against the inner surface of the intermediate transfer belt 12 so that the outer surface of the intermediate transfer belt 12 winds a part of the outer peripheral surface of the photosensitive drum 101 to obtain a predetermined nip amount. Is provided. As a result, the image transfer portion (transfer nip portion), which is a contact area between the photosensitive drum 101 and the intermediate transfer belt 12, is not a linear shape but a surface shape having a predetermined width. Therefore, the transfer efficiency to the transported recording medium (paper) can be improved.

  When image data of only a part of the hues of black, cyan, magenta, and yellow is input, a part of the four photosensitive drums 101a to 101d corresponding to the hue of the input image data is input. The electrostatic latent image and the toner image are formed only on the photosensitive drum. For example, when forming a monochrome image, an electrostatic latent image and a toner image are formed only on the photosensitive drum 101a corresponding to the black hue. Further, only the black toner image is transferred to the outer peripheral surface of the intermediate transfer belt 12.

  The primary transfer units 13a to 13d are configured by covering the surface of a shaft made of a metal (for example, stainless steel) having a diameter of 8 to 10 mm with a conductive elastic material (for example, EPDM, urethane foam, or the like). . Further, the primary transfer units 13a to 13d uniformly apply a high voltage to the intermediate transfer belt 12 by a conductive elastic material. In the present embodiment, the primary transfer units 13a to 13d are used as transfer electrodes, but a brush or the like can also be used.

  The intermediate transfer belt 12 is disposed above the photosensitive drums 101a to 101d, and the surface thereof is configured to contact the outer peripheral surface of the photosensitive drums 101a to 101d. The intermediate transfer belt 12 is stretched between the driving roller 12a and the driven roller 12b to form a loop-shaped movement path. It is configured to move in the sub-scanning direction by the driving force of the driving roller 12a.

  The outer peripheral surface of the intermediate transfer belt 12 faces the photosensitive drum 101d, the photosensitive drum 101c, the photosensitive drum 101b, and the photosensitive drum 101a in this order. Primary transfer units 13a to 13d are arranged at positions facing the respective photosensitive drums 101a to 101d with the intermediate transfer belt 12 interposed therebetween. Each of the positions where the intermediate transfer belt 12 faces the photosensitive drums 101a to 101d is a primary transfer position.

  The intermediate transfer belt 12 is a belt member formed endlessly using a film having a thickness of about 100 μm to 150 μm. The material of the intermediate transfer belt 12 is mainly polyimide, polycarbonate, thermoplastic, elastomer, alloy or the like.

  The secondary transfer unit 14 is pressed against the outer peripheral surface of the intermediate transfer belt 12 whose inner peripheral surface is in contact with the peripheral surface of the driving roller 12a at a predetermined nip pressure during image formation. In order to constantly obtain the nip pressure, either the secondary transfer unit 14 or the driving roller 12a is made of a hard material such as metal, and the other is a soft material such as an elastic roller (elastic rubber roller or foaming resin). Roller).

  The fixing device 1 according to the present embodiment fixes an unfixed toner image formed on the surface of a recording medium (paper) onto the recording medium by heat. The fixing device 1 is disposed on the downstream side of the secondary transfer unit 14.

  In the image forming apparatus 100 of the present embodiment, the fixing and transport are controlled to be performed at a maximum fixing speed of 225 mm / sec and a maximum copying speed of 50 sheets / minute (A4 horizontal feed). The fixing device 1 will be described later in detail.

  The internal paper feed unit 16 includes a paper feed tray 26 for storing recording paper used for image formation, and a plurality of recording media (paper) are arranged.

  The paper feed tray 26 has a configuration capable of storing a large amount of paper having a size defined by the specifications of the image forming apparatus or a size predetermined by the user.

  A pickup roller 16 a is provided on one end of the paper feed tray 26, and comes into contact with the surface of one end of the paper at the top of the paper set in the paper feed tray 26, and is caused by the frictional resistance of the rollers. Deliver and transport one sheet at a time.

  Further, on the side surface of the image forming apparatus 100, a manual paper feed tray 17 that is mainly used when printing on an irregular size sheet is disposed.

  A registration roller 19 is provided below the secondary transfer unit 14. The registration roller 19 is configured to align the leading edge of the sheet fed from the internal sheet feeding unit 16 and the leading edge of the toner image on the intermediate transfer belt 12 and convey the sheet to the secondary transfer unit 14 side.

  A paper discharge tray 18 is provided on the upper surface of the image forming apparatus main body 100, and printed recording paper is discharged face down and stacked.

  The paper discharge roller 18a is rotatably arranged in both forward and reverse directions, and is used when forming a single-sided image for forming an image on one side of the paper and for forming a second-side image in double-sided image formation for forming an image on both sides of the paper. Driven in the forward direction, the paper is discharged to the paper discharge tray 18.

  In the image forming apparatus 100, a substantially vertical direction for feeding the paper stored in the internal paper feeding unit 16 to the paper discharge tray 18 between the secondary transfer roller 14 a and the intermediate transfer belt 12 and via the fixing device 1. Direction paper transport path R1 is provided.

    The transport roller r is a small roller for promoting and assisting the transport of the recording medium (paper), and a plurality of transport rollers r are provided along the paper transport path R1.

  A pickup roller 16a, a conveyance roller r, a registration roller 19 and a paper discharge roller 18a are arranged in the paper conveyance path R1.

  Further, inside the image forming apparatus 100, a sheet conveyance path R2 in which a pickup roller 17a conveyance roller r is arranged is formed between the manual sheet feeding tray 17 and the registration roller 19. Further, a sheet conveying path R3 is formed between the paper discharge roller 18a and the upstream side of the registration roller 19 in the sheet conveying path R1.

  In addition, the image forming apparatus 100 includes a control unit 24 for controlling the operation of the apparatus. The control unit 24 includes, for example, a microcomputer, a ROM (Read Only Memory) that stores a control program indicating the procedure of processing executed by the microcomputer, and a RAM (Random Access Memory) that provides a work area for work. A non-volatile memory that backs up and holds data necessary for control, a circuit for inputting signals from sensors and switches, including an input buffer and an A / D conversion circuit, a motor, a solenoid, or a lamp And an output circuit including a driver for driving the.

  Further, as shown in FIG. 5, the control unit 24 receives a signal of the detected temperature detected by the temperature detecting means L3 (thermistor) of the fixing device 1. The ROM has a temperature conversion table for converting a detected temperature signal from the temperature detecting means L3 (thermistor) of the fixing device 1 into temperature data. The control unit 24 collates the detected temperature signal detected by the temperature detecting means L3 (thermistor) of the fixing device 1 with the temperature conversion table, and adjusts the output of the laser beam of the fixing device in accordance with the detected temperature. .

  Next, an image forming process in the image forming apparatus 100 will be described.

  When the power switch of the image forming apparatus 100 is turned on, the charging unit 103a uniformly charges the surface of the photosensitive drum 101a. When the control unit 24 receives a command for instructing image formation, the optical system unit E performs exposure by irradiating the photosensitive drum 101a with laser light emitted from the light source. An electrostatic latent image is formed on the photosensitive drum 101a based on the input image information. Similarly, electrostatic latent images corresponding to the respective colors are formed on the other photosensitive drums 101b to 101d.

  The developing units 102a to 102d supply toners corresponding to the respective colors to make the electrostatic latent images of the respective hues formed on the photosensitive drums 101a to 101d conspicuous into toner images of the corresponding hues.

  The primary transfer units 13 a to 13 d transfer the noticeable toner images of each hue onto the intermediate transfer belt 12. For this reason, a primary transfer bias having a polarity opposite to the toner charging polarity is applied to the primary transfer units 13a to 13d.

  Each hue toner image is stacked on the intermediate transfer belt 12, and conveyed to the contact position between the secondary transfer unit 14 and the sheet by the rotation of the intermediate transfer belt 12.

  Further, the secondary transfer unit 14 transfers the toner images stacked on the intermediate transfer belt 12 to a sheet. Therefore, the secondary transfer unit 14 is applied with a high voltage having a polarity opposite to the charging polarity of the toner.

  The sheet on which the toner image is transferred as a visible image is conveyed to the fixing device 1. The toner image is fused to the paper by being heated by the laser beam irradiation of the fixing device 1. The sheet on which the toner image is fused is discharged to the discharge tray 18 through the discharge roller 18a.

  Next, the sheet conveyance executed in the image forming apparatus 100 will be described in detail.

  When a document is read by a scanner image reading unit (not shown) and an image forming command is received by the control unit 24, either the paper feed tray 26 or the manual paper feed tray 17 is selected based on the input image information. . The control unit 24 controls a plurality of transport rollers r provided along the paper transport paths R 1 and P 2 and transports the paper stored in the selected paper feed tray toward the registration rollers 19. As a result, the paper reaches before the registration roller 19 and stops temporarily.

  The control unit 24 re-rotates the registration roller 19 to temporarily stop the sheet conveyed through the sheet conveyance path at a predetermined position and measure the next conveyance timing. At the position where the secondary transfer roller 14a and the intermediate transfer belt 12 are in pressure contact with each other, the control unit 24 positions the sheet so that the position of the leading end of the sheet matches the front end of the toner image formed on the intermediate transfer belt 12. It is conveyed to the secondary transfer unit 14.

  The transported paper is transferred with the toner image on the intermediate transfer belt 12 by the secondary transfer unit 14 and further transported to the fixing device 1 where unfixed toner on the paper is melted by heat and fused to the paper. . After passing through the fixing device 1, it is naturally cooled and fixed on the paper. Then, the paper is discharged onto the paper discharge tray 18 through the paper discharge roller 18a.

  Next, the fixing device 1 according to the embodiment of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 2, the fixing device 1 according to the present embodiment includes a laser head (laser irradiation unit) L1, a paper conveying device L2, and a temperature detection unit L3 (thermistor).

  The fixing device 1 according to the present embodiment fixes the toner image on the recording medium by applying heat to an unfixed toner image formed on the surface of the recording medium (paper P).

  Specifically, based on a predetermined fixing speed and copying speed, a recording medium (paper P) carrying an unfixed toner image 40 in an area (laser irradiation area 10) irradiated with laser light on the paper conveying device L2. Then, laser light is irradiated from the fixing device 1 and fixing is performed by the heat of the laser light.

  An unfixed toner image is, for example, a toner contained in a developer such as a non-magnetic one-component developer containing a non-magnetic toner, a non-magnetic two-component developer containing a non-magnetic toner and a carrier, and a magnetic developer containing a magnetic toner. Formed with. Since color toners (yellow, magenta, cyan) have a lower absorption rate of laser light than monochrome toners (black), the same adsorption rate as that of monochrome toners is ensured by adding an infrared absorber.

  The sheet conveying device L2 includes a fixing driving roller 33, a fixing driven roller 36, a suction charger 37, a separation charger 30, a static elimination charger 34, a separation claw 32, a fixing unit motor (not shown), and a fixing conveyance belt 35. Yes.

The fixing conveyance belt 35 is made of a polyimide resin having a belt thickness of 75 μm and a volume resistivity of 10 ¹⁶ Ω · cm, and is stretched by a fixing driving roller 33 and a fixing driven roller 36.

  The fixing drive roller 33 is configured to be rotationally driven at an arbitrary speed by a fixing unit motor (not shown). As shown in FIG. 2, the fixing conveyance belt 35 rotates at an arbitrary speed in the direction of the arrow by the rotation of the fixing driving roller 33.

  A suction charger 37, a separation charger 30, a charge removal charger 34, and a separation claw 32 are provided around the fixing conveyance belt 35.

  On the inner peripheral surface side of the fixing and conveying belt 35, temperature detecting means L3 (thermistor) for detecting the temperature of the fixing and conveying belt 35 is installed. Based on the temperature detected by the temperature detecting means L3, the irradiation amount of the laser light is controlled. This control will be described in detail later. The arrangement position of the thermistor L3 is not limited to the inner peripheral surface side of the fixing conveyance belt 35 as long as the temperature of the conveyance belt 35 or the temperature of the recording medium (paper P) can be properly detected.

  Next, the fixing operation in the fixing device 1 of the present invention will be specifically described with reference to FIG.

  In the fixing device 1, the recording medium (paper P) carrying the unfixed toner image 40 conveyed from the secondary transfer unit 14 is interposed between the fixing conveyance belt 35 on the fixing driven roller 36 and the suction charger 37. Be transported.

  By applying an electric charge to the paper P by the suction charger 37, dielectric polarization occurs between the paper P and the fixing conveyance belt 35, respectively. Due to this dielectric polarization, the sheet P is electrostatically adsorbed onto the fixing conveyance belt 35.

  The sheet P is conveyed to the laser irradiation area 10 by driving the fixing driving roller 33. An unfixed toner image 40 is carried on the paper P.

  The laser head L1 irradiates the unfixed toner image 40 on the paper P with laser light. Fixing is performed by the heat of the laser beam.

  After the toner image is fixed in the laser irradiation area 10, the paper P is conveyed between the separation charger 30 and the fixing driving roller 33 while being electrostatically attracted to the fixing conveyance belt 35.

  The fixing drive roller 33 is made of a conductive material and is grounded. Accordingly, the separation charger 30 neutralizes the paper P and weakens the electrostatic attraction between the fixing conveyance belt 35 and the paper P.

  With the electrostatic attraction force weakened, the fixing conveyance belt 35 is conveyed by driving the fixing driving roller 33. Since the fixing conveyance belt 35 has a large curvature, the leading end portion of the paper P floats from the fixing conveyance belt 35. Further, the paper P is completely separated from the fixing conveyance belt 35 by the separation claw 32.

  The fixing conveyance belt 35 from which the sheet P has been peeled is discharged to the suction position of the sheet P again after the outer surface and the inner surface are discharged by the charge removal charger 34.

  Next, the laser head (laser irradiation means) L1 according to the present embodiment will be described in detail with reference to FIGS.

    The laser head (laser irradiation means) L1 records a toner image by irradiating the unfixed toner image 40 carried on the recording medium (paper P) conveyed to the laser irradiation area 10 on the fixing conveyance belt 35 with a laser beam. Fix to media.

  As shown in FIGS. 2 and 3, the laser head (laser irradiation means) L1 includes a plurality of laser elements 11 (semiconductor laser array), a heat radiating plate 9 (heat sink), a plurality of convex lenses 8, a lens holder 7, and a photodiode. 2, a silicon substrate 3, a wire bond line 4, a surface electrode 5, a ceramic substrate 6, and a laser control circuit (not shown).

  The heat sink 9 (heat sink) according to the present embodiment is made of an aluminum alloy. The heat sink 9 (heat sink) has a heat resistance of 16 ° C./W arranged in a row and a total heat resistance of 0.16 ° C./W, but is not limited to this.

  As shown in FIG. 3, a light receiving element (photodiode 2) is disposed in the vicinity of each laser element 11, the light emission amount of the laser element 11 is detected, and the light emission amount detected by the photodiode 2 is detected in the laser head L1. Is fed back to the laser control circuit (not shown), and control is performed to vary or keep the output of the light amount of each laser element 11 constant.

  The laser control circuit and the photodiode 2 are integrally formed (monolithic), constitute a silicon substrate 3, and further a laser element 11 is mounted. The laser element 11 and the silicon substrate 3 are electrically connected by a wire bond line 4.

  A plurality of silicon substrates 3 on which the laser elements 11 are mounted are arranged on a ceramic substrate 6 made of ceramic. The electrodes (not shown) of the plurality of silicon substrates 3 and the surface electrodes 5 of the ceramic substrate 6 are electrically connected by wire bonding or the like.

  A plurality of convex lenses 8 of the condensing optical system are disposed in the lens holder 7. The laser light emitted from each laser element 11 passes through the corresponding convex lens 8 and is irradiated onto the paper P on the laser irradiation area 10.

  As described above, the laser head L1 is a lens holder in which the ceramic substrate 6 on which the plurality of silicon substrates 3 on which the laser elements 11 are mounted is arranged, the heat sink 9 (heat sink), and the plurality of convex lenses 8 are disposed. 7.

  In the laser head L1, rather than incorporating each convex lens 8 in a holder made of resin, a lens-lens holder integrated molded product made of resin, or a lens array such as a flat microlens manufactured by ion exchange of flat glass into a lens shape It is preferable that Further, a configuration in which the plurality of convex lenses 8 of the condensing optical system are omitted and the unfixed toner image 40 is irradiated in a parallel state with the laser light is also possible.

  Next, an arrangement interval (arrangement pitch) of a plurality of laser elements for different sizes of paper will be described.

  As shown in FIG. 3, in the first embodiment, when fixing an unfixed toner image on a predetermined size paper (for example, A4 size paper) and a paper having a size smaller than the predetermined size (for example, When fixing an unfixed toner image on a B5 size paper), a plurality of laser elements used in common are positioned at the center of the row among the plurality of laser devices arranged in a row. This is a laser element (a laser element in the common region W1 shown in FIG. 3).

  Further, an unfixed toner image (an unfixed toner image on a portion where the A4 size paper and the B5 size paper do not overlap) on a portion where the paper of a predetermined size and the paper of a size smaller than the predetermined size are not shared is fixed. In this case, the plurality of laser elements are laser elements (laser elements in the regions X1 and X2 shown in FIG. 3) at the end of the row among the plurality of laser devices arranged in one row. That is, the laser elements in the regions X1 and X2 (hereinafter referred to as non-common regions X1 and X2) are used for fixing only a predetermined size of paper.

  A laser element used in common for a sheet of a predetermined size and a sheet of a size smaller than a predetermined size and disposed in a central area of the laser element array (hereinafter referred to as a common area W1) has a wavelength of 780 mm. The arrangement pitch P1 between adjacent laser elements is 0.15 mm. In each laser element, the rated output is 150 mW, and the laser spot diameter d1 on the laser irradiation area 10 is 0.3 mm.

  On the other hand, a laser element that is used only for a sheet of a predetermined size and is disposed in an end area (non-common area X1, X2) of the laser element array emits a laser beam having a wavelength of 780 mm and is adjacent to the laser element. The arrangement pitch P1 between them is 0.3 mm. In each laser element, the rated output is 150 mW, and the laser spot diameter d2 on the laser irradiation area 10 is 0.3 mm.

  In the first embodiment, the rated output of the laser elements in the common area W1 is controlled to be 75 mW, which is half the rated output of the laser elements in the non-common areas X1 and X2.

  As described above, since the laser elements in the common area W1 are used in common for a sheet of a predetermined size and a sheet of a size smaller than the predetermined size, deterioration tends to occur. However, since the output of the laser element in the common area W1 is controlled to be half of the output of the laser elements in the non-common areas X1 and X2, there is less deterioration than using the rated output, and the product life of the laser element Can be extended.

  In addition, the self-heating of each laser element is reduced as compared with the rated output, and the deterioration due to the next self-heating is alleviated and the product life of the laser element can be extended.

For example, the paper width in the direction orthogonal to the paper conveyance direction when vertically feeding B5 size paper is set to a small size, and the paper width in the direction orthogonal to the paper conveyance direction when vertically feeding A4 size paper is set to a normal size. In this case, the common area between the A4 size and the B5 size has a width of 182 mm. With this width of 182 mm, the total number of laser elements used for fixing reaches 1606. By performing the above control, deterioration of many laser elements can be delayed.
<Second Embodiment>

  Next, a second embodiment of the present invention will be described in detail with reference to FIGS. FIG. 6 is a front view of a laser head unit according to the second embodiment of the present invention. FIG. 7 is a top view of a laser head unit according to the second embodiment of the present invention. In the fixing device according to the second embodiment of the present invention, since the other components except the configuration of the laser head are the same as those in the first embodiment, the description of the components other than the laser head will be given. Omitted.

  As shown in FIGS. 6 and 7, the laser head L4 according to the second embodiment includes a plurality of laser elements 11a (semiconductor laser array), a heat radiating plate 9a (heat sink), a plurality of convex lenses 8a, a lens holder 7a, A photodiode 2a, a silicon substrate 3a, a wire bond line 4a, a surface electrode 5a, a ceramic substrate 6a, and a laser control circuit (not shown) are provided.

  As shown in FIG. 6, a light receiving element (photodiode 2a) is disposed in the vicinity of each laser element 11a to detect the light emission amount of the laser element 11a, and the light emission amount detected by the photodiode 2a is stored in the laser head L4. Is fed back to a laser control circuit (not shown), and control is performed to vary or keep the output of the light amount of each laser element 11a constant.

  The laser control circuit and the photodiode 2a are integrally formed (monolithic), constitute a silicon substrate 3a, and further a laser element 11a is mounted. The laser element 11a and the silicon substrate 3a are electrically connected by a wire bond line 4a.

  A plurality of silicon substrates 3a on which the laser elements 11a are mounted are arranged on a ceramic substrate 6a made of ceramic. In the second embodiment, as shown in FIG. 7, the plurality of laser elements on the ceramic substrate 6 a are arranged in two rows in the longitudinal direction of the fixing conveyance belt 35 in the common region W <b> 2. A first column F1 and a second column F2 are configured.

  Further, as shown in FIG. 7, the arrangement pitch P3 between the laser elements in the first row F1 and the laser elements in the second row F2 in the common region W2 is the same as that of the laser elements in the first row F1 in the non-common regions X3 and X4. Different from the arrangement pitches P4 and P5. In the second embodiment, the laser beam emitted from the laser element in the second row passes through the intermediate point between the laser elements in the first row F1, but the present invention is not limited to this. .

  The electrodes (not shown) of the plurality of silicon substrates 3a and the surface electrode 5a of the ceramic substrate 6a are electrically connected by wire bonding or the like.

  The plurality of convex lenses 8a of the condensing optical system are disposed in the lens holder 7a. The laser light emitted from each laser element 11a passes through the corresponding convex lens 8a and is irradiated onto the paper P on the laser irradiation area 10a.

  As described above, the laser head L4 includes the ceramic substrate 6a in which the plurality of silicon substrates 3a on which the laser elements 11a are mounted are arranged in a plurality of rows, the heat radiating plate 9a (heat sink), and the plurality of convex lenses 8a. The lens holder 7a is arranged.

  As shown in FIG. 6, it is commonly used for fixing an unfixed toner image on a paper of a predetermined size and fixing an unfixed toner image on a paper of a size smaller than a predetermined size. The plurality of laser elements to be performed are located at the center of the ceramic substrate 6a (common region W2). Therefore, in the second embodiment, as shown in FIG. 7, the laser elements in the common region W2 are configured in two rows (first row F1, and second row F2).

  In addition, a plurality of laser elements for fixing an unfixed toner image on a portion that is not shared by a sheet of a predetermined size and a sheet of a size smaller than the predetermined size are positioned at both ends of the ceramic substrate 6a (non-common area X3, X4). As shown in FIG. 7, the laser elements in the non-common regions X3 and X4 are configured in one row (first row F1).

In the second embodiment, the first row is used in common for a predetermined size paper and a smaller size paper, and is arranged at the center position (common area W2) of the ceramic substrate 6a. The laser elements in F1 and the second row F2 emit laser light having a wavelength of 780 mm,
The arrangement pitch P3 between the laser elements in the first row F1 and the second row F2 is 0.15 mm. In each laser element, the rated output is 150 mW, and the laser spot diameter d3 on the laser irradiation area 10a is 0.3 mm.

Further, in the common region W2, the continuous lighting time Ton1 the first row F1 and laser device 11a of the second row F2, and 10x10 ^-3 seconds, the off time Toff1 and 20x10 ^-3 seconds.

  On the other hand, laser elements that are used only for paper of a predetermined size and are arranged in the end area (non-common area X3, X4) of the laser element array in the first array F1 emit laser light having a wavelength of 780 mm. The arrangement pitch P4 between adjacent laser elements in the first row F1 is 0.3 mm. In each laser element, the rated output is 150 mW, and the laser spot diameter d4 on the laser irradiation area 10a is 0.3 mm.

In the non-common regions X3 and X4, the continuous lighting time Ton2 of the laser elements 11a in the first column F1 is set to 20 × 10 ⁻³ seconds, and the turn-off time Toff2 is set to 20 × 10 ⁻³ seconds.

  In the second embodiment, the continuous lighting times Ton1 of the laser elements in the first column F1 and the second column F2 of the common area W2 are the continuous lighting times Ton2 of the laser elements in the first column F1 of the non-common areas X3 and X4. To (P3 / P4) times (a half value in the second embodiment).

  Since the laser elements in the common area W2 are commonly used for a predetermined size paper and a smaller size paper, deterioration tends to occur. However, the arrangement pitch P3 of the laser elements in the first row F1 and the second row F2 of the common region W2 is arranged to be substantially half the arrangement pitch P4 between adjacent laser elements in the first row F1. Therefore, the continuous lighting time Ton1 of the laser elements in the first column F1 and the second column F2 of the common area W2 can be shorter than the continuous lighting time Ton2 of the laser elements in the first column F1 of the non-common areas X3 and X4. . Accordingly, the self-heating of the laser element in the common region W2 can be controlled to the minimum necessary, and the deterioration due to the self-heating is alleviated and the product life of the laser element can be extended.

DESCRIPTION OF SYMBOLS 1 Fixing device 2 Photodiode 3 Silicon substrate 4 Wire bond line 5 Surface electrode 6 Ceramic substrate 7 Lens holder 8 Convex lens 9 Heat sink 10 Laser irradiation part 11 Laser element 100 Image forming apparatus L1 Laser head L2 Paper conveyance apparatus

Claims (6)

A fixing device comprising laser irradiation means for irradiating a recording medium to be conveyed with laser light to heat and fix an unfixed toner image on the recording medium,
The laser irradiation means includes
The plurality of laser elements that emit the laser light are arranged in a row in a direction perpendicular to the direction in which the recording medium is conveyed, and the plurality of laser elements that are used in common for the recording media having different sizes And a plurality of laser elements that are not used in common are arranged at a different density and are controlled to operate differently.   In the laser irradiation means, the pitch of the plurality of laser elements used in common for a recording medium of a predetermined size and a recording medium of a size smaller than the predetermined size is limited to a recording medium of a predetermined size. The fixing device according to claim 1, wherein the fixing device is different in pitch from the plurality of laser elements used.   In the laser irradiation means, the power consumption of each of the plurality of laser elements commonly used for a recording medium of a predetermined size and a recording medium of a size smaller than the predetermined size is a recording of a predetermined size. The fixing device according to claim 1, wherein power consumption of each of the plurality of laser elements used only for a medium is different.   In the laser irradiation means, the lighting times of the plurality of laser elements used in common for a recording medium of a predetermined size and a recording medium of a size smaller than the predetermined size are recorded on the recording medium of a predetermined size. 4. The fixing device according to claim 1, wherein the fixing device is controlled to be different from a lighting time of the plurality of laser elements that are used only. 5. In the laser irradiation means, the number of rows of the plurality of laser elements used in common for a recording medium of a predetermined size and a recording medium of a size smaller than the predetermined size is a recording medium of a predetermined size 5. The fixing device according to claim 1, wherein the fixing device is different from the number of rows of the plurality of laser elements that are used only for the laser beam. An optical scanning device that deflects and scans laser light;
A photosensitive drum on which an electrostatic latent image is formed by irradiation of the laser beam by the optical scanning device;
Developing means for developing the electrostatic latent image formed on the photosensitive drum by attaching a developer;
Transfer means for transferring the developer attached by the developing means to a recording medium;
In an image forming apparatus comprising:
An image forming apparatus using the fixing device according to claim 1 as the fixing device.

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