JP2005070287A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact image forming apparatus, in a paper conveyance section provided on the image forming apparatus. <P>SOLUTION: The image forming apparatus forms an image on a recording medium conveyed from a paper feed part by a longitudinal conveyance unit and fed to a photoreceptor (image carrier) via a resist roller 53b. In the image forming apparatus, a red developing unit (developing unit) 33 is disposed so as to be drawn from a transverse conveyance unit. A receiving base 3 for steadily drawing the red developing unit 33 is disposed on the transverse conveyance unit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using an electrophotographic process. Specifically, the present invention relates to a paper transport unit provided in the image forming apparatus.

Conventionally, an image forming unit or the like constituting an image forming apparatus of an electrophotographic process can be pulled out from the main body of the image forming apparatus by using a slide rail or the like, and the developing unit can be easily replaced. ing.
For example, a part of the transfer paper conveyance path constituting member can be pulled out as a horizontal conveyance unit by moving it from the machine body by a pair of slide rails in a direction substantially perpendicular to the conveyance direction, attached to the conveyance unit, and its drawing operation A position restricting member fixed to an operation lever portion for performing the operation, a position that is movable with respect to the machine body to a certain position in the direction of pulling out the lateral conveyance unit, and a position that can be engaged with the front surface of the position restricting member There is disclosed an image forming apparatus having a displaceable stopper member and capable of switching a stop position at the time of pulling out the lateral conveyance unit to a plurality of positions (for example, Patent Document 1).
According to this image forming device, when a general user performs operations such as removing jammed paper, the horizontal conveyance unit is pulled out only to the minimum necessary by the slide rail, and is necessary for work during maintenance and inspection by a service person. The transport unit can be pulled out to a safe position, which is effective for improving safety and workability.
Japanese Patent No. 2633934

  However, for example, the mechanism for pulling out the developing unit using a pair of slide rails has a structure for fixing the unit for pulling out to the slide rail in addition to a space for storing the slide rail itself, and the slide rail as the image forming apparatus main body. There is a problem in that a configuration for fixing the configuration to the image forming apparatus is required, and a space for storing the configuration in the image forming apparatus is required, the apparatus is enlarged, and the configuration is complicated. In addition, there is a problem that costs increase because the number of components of the entire apparatus increases.

  Accordingly, an object of the present invention is to provide a compact image forming apparatus.

The invention according to claim 1 is an image forming apparatus for forming an image by feeding a recording medium conveyed by a vertical conveyance unit from a paper feeding unit to an image carrier through a registration roller.
The developing unit is provided so as to be capable of being pulled out with respect to the lateral transport unit, and a receiving base for stably pulling out the developing unit is provided on the lateral transport unit.

  According to the first aspect of the present invention, the development unit is provided so as to be able to be drawn out from the horizontal conveyance unit, and a receiving base for stably pulling out the development unit is provided on the horizontal conveyance unit. In order to pull out the developing unit from the lateral conveyance unit or the apparatus main body when replacing the unit, the developing unit is pulled out by sliding on the receiving table without installing a separate slide rail as in the prior art.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the cradle is formed so as to cover the registration roller.

  According to the invention of claim 2, since the cradle is formed so as to cover the registration roller, dust such as toner falls from the image forming unit on the registration roller and adheres to the registration roller. The recording medium on which an image is formed by passing through is not soiled.

  A third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein the cradle is provided with a standing surface for reinforcement.

  According to the third aspect of the present invention, the cradle is provided with a standing surface for reinforcement, so that a relatively heavy image forming unit is reinforced when being placed on the cradle and pulled out, or a registration roller that presses against the recording medium. It is possible to reinforce the cradle against the pressing force.

  According to the first aspect of the present invention, the image forming apparatus is formed by forming a receiving table on the upper side of the horizontal conveyance unit instead of the guide rail used so far when the developing unit provided in the image forming apparatus is taken in and out. It can be downsized.

  According to the second aspect of the invention, by forming the cradle so as to cover the upper registration roller, dust such as toner generated during image formation falls from the developing unit above the registration roller. It is possible to prevent the occurrence of image defects by adhering to the registration rollers and smearing a recording medium on which an image is formed through the registration rollers.

  According to the third aspect of the present invention, since the pedestal is provided with a standing surface for reinforcement, the relatively heavy development unit is reinforced when being placed on the pedestal and pulled out, and the registration roller that presses against the recording medium It is possible to reinforce the cradle against the pressing force. Therefore, a member for reinforcing the pressing force of the registration roller is not separately provided, and the number of parts can be reduced.

  A configuration of a digital copying machine as an example of the image forming apparatus of the present invention will be described. In FIG. 1, the mechanism of this digital copying machine is roughly constituted by a copying machine main body 1, an automatic document feeder (ADF) 100, a paper discharge tray 200, and a paper feed unit (paper feed unit) 300.

  The automatic document feeder 100 feeds the originals stacked on the original feed tray 101 one by one onto the contact glass 10 on the copying machine main body 1 side, reads the images, and then discharges them onto the discharge tray 105. It is configured as follows. The document on the document feeder 101 is aligned in the width direction by a side fence (not shown), separated from the lowermost document by the feed roller 102, and fed to the contact glass 10 by the transport belt 103. Paper.

  The feeding unit 107 is provided with a document width detection sensor 108 and a document length detection sensor 109. The size of the document fed from the automatic document feeder 100 is detected by both the sensors. The original on the contact glass 10 is discharged onto the paper discharge tray 105 by the transport belt 103 and the paper discharge roller 104 after the reading is completed.

On the other hand, when reading a double-sided document, the document on the document feeder 101 is separated from the document at the bottom by the feed roller 102 and fed, and passes through the contact glass 10 by the conveyor belt 103. It is reversed by the reversing claw 106, fed again onto the contact glass 10, and the back surface is read. Next, the original on the contact glass 10 is transported by the transport belt 103 after being read from the back surface, reversed by the reversing claw 106, fed again onto the contact glass 10, and the front surface is read.
Then, the original after the front surface reading is discharged onto the discharge tray 105 by the conveyance belt 103 and the discharge roller 104.

  As shown in FIG. 2, the automatic document feeder 100 is closed around hinges 81 and 82, and a claw 83 is provided on the upper surface of the copier body 1 in the vicinity of the hinge 81. A hole 84 is provided in the lower surface of the automatic document feeder 100 at a position where the claw 83 faces when the document feeder 100 is closed, and the claw 83 is inserted into the hole 84 when the automatic document feeder 100 is closed. It has become. Inside the automatic document feeder 100 adjacent to the hole 84, a lift-up detection sensor 85 and a document detection timing sensor 86 for detecting the presence or absence of the claw 83 inserted through the hole 84 are provided.

  The lift-up detection sensor 85 detects the claw 83 when the automatic document feeder 100 is completely closed (lifted down) and is turned on, and when the automatic document feeder 100 is opened (lifted up). Will be off. The completely closed state refers to a state in which a part of the lower surface side of the automatic document feeder 100 is in contact with the upper surface of the copying machine main body 1.

  On the other hand, the document detection timing sensor 86 is provided for controlling the timing of detecting the size of the document on the contact glass 10 based on the detection result of the document size detection sensor described later. When the opening angle is within a predetermined angle, the claw 85 is detected and turned on. This predetermined angle is a slight angle, and when the operator manually opens the automatic document feeder 100, both the lift-up detection sensor 85 and the document detection timing sensor 86 are turned off. Reference numerals 87 and 88 are end face scales.

  As shown in FIG. 3, document size detection sensors 91 to 93 are provided below the contact glass 10. As shown in FIG. 4, each of the document size detection sensors 91 to 93 irradiates the light emitted from one light emitting diode 91a by dispersing it into three beams, and irradiates the reflected light to three light beams inside the optical system. It is a reflective sensor that receives light by the light receiving element 91b, and detects the presence or absence of a document by receiving only reflected light from the document surface through the contact glass 10 from the inside of the optical system.

The document size detection sensors 91 to 93 are always in operation, and each light receiving element is turned on when a document on the contact glass 10 is detected, and is turned off when a document is not detected. The document size detection sensors 91 to 93 are arranged according to the sizes of a plurality of types of documents placed at predetermined positions on the contact glass 10.
From this, it is determined whether or not there is a document on the contact glass 10, and the size of the document on the contact glass 10 is detected.

Returning to FIG. 1, the copier body 1 includes a scanner for reading a document, an image processing unit, a plotter, and the like. The scanner has a contact glass 10 for placing a document and an optical scanning system. The optical scanning system includes an exposure lamp 11, a first mirror 12, a second mirror 13, a third mirror 14, a lens 15, a full color CCD 16, and the like. Have. The exposure lamp 11 and the first mirror 12 are mounted on a first carriage, and the first carriage moves in the sub-scanning direction at a constant speed by a stepping motor when reading a document. The second mirror 13 and the third mirror 14 are mounted on the second carriage, and the second carriage moves at a speed half that of the first carriage by the stepping motor when reading the document.
The original on the contact glass 10 is optically scanned by the movement of the first and second carriages, and is imaged on the light receiving surface of the CCD 16 by the lens 15 and subjected to photoelectric conversion.

  The image signal separated into red (R), green (G), and blue (B) by the full color CCD 16 is A / D converted by an image processing circuit and then subjected to various image processing by an image processing unit. Then, at the time of copying, the data is copied onto the recording paper by the writing unit.

  The writing unit includes a laser output unit 20, an fθ lens 21, and a mirror 22. The laser output unit 20 includes a laser diode (LD) that is a laser light source, a polygon mirror and a polygon motor (not shown). The laser output unit 20 emits laser light of a black signal modulated according to the image read by the scanner during copying, and a latent image is formed on the photoconductor 30.

  Around the photosensitive member (image carrier) 30, there are a black developing unit 32, an LED writing unit 31 for writing a red signal image, a red developing unit (developing unit) 33, a transfer device and a separator not shown. The toner image on the photoconductor 30 is recorded on a sheet. As will be described later, the red developing unit 33 is set on one of the registration rollers 53 via the cradles 2 and 3. The paper is selectively fed from one of the first tray 50, the second tray 51, the third tray 310, the fourth tray 320, and the fifth tray 330 in the sheet feeding unit 300, respectively. The paper is fed by the roller pair of the separation roller 43.

  FIG. 5 shows an internal configuration of the fixing device 55. As illustrated, the fixing device 55 includes a fixing roller 700 and a pressure roller 701 that is in pressure contact with the fixing roller 700. The surface of the fixing roller 700 is coated with a heat-resistant release layer such as PFA or PTFE, and a heat source 702 is provided inside. As the heat source 702, a halogen heater, an infrared heater (nichrome wire), or the like is used.

  A fixing temperature sensor 703 as temperature detecting means is provided on the peripheral surface of the fixing roller 700, and a pressure temperature sensor 704 as temperature detecting means is provided on the peripheral surface of the pressure roller 701. This fixing temperature sensor. 703. Based on the temperature detection signal from the pressure temperature sensor 704, the heat source 702 is controlled so that the temperature of the fixing roller 700 and the pressure roller 701 becomes a certain temperature, and the amount of heat supplied to the transfer paper P is controlled. For control, the pressure mechanism is controlled so that the nip width between the fixing roller 700 and the pressure roller 701 can be changed. The fixing roller 700 is rotated by a driving mechanism (not shown), and performs fixing processing by applying heat and pressure to the transfer paper P while conveying the transfer paper P in cooperation with the pressure roller 701.

  The pressure roller 701 has a surface made of a heat-resistant rubber layer such as silicon rubber. The pressure roller 701 is pivotally supported at both ends of the shaft so as to be rotatable, and is always urged in a direction away from the fixing roller 700 by an urging means (not shown). On the other hand, the pressure roller 701 is lifted from below the shaft by a pressure mechanism and pressed against the lower portion of the fixing roller 700.

  In the pressurizing mechanism, the stepping motor 710 rotates forward (direction A), and the gear 713 is driven from the coaxial gear 711 through the idler gear 712. The shaft of the gear 713 is a feed screw 714 that pulls the anchor 715 in the horizontal direction (C direction). A spring 716 is hung on the anchor 715, and one is hung on the link 717. As the anchor 715 moves horizontally, the link 717 rotates around the fulcrum 718. A lever 719 is fitted to one end of the link 717, rotates around a fulcrum 720, and applies pressure to the pressure roller 701.

  Further, when the stepping motor 710 reversely rotates (B direction), the anchor 715 is pushed back in the horizontal direction (D direction), the lever 719 rotates about the fulcrum 720, and the pressure roller 701 is pulled down to release pressure. At this time, the anchor 715 is provided with a home position detection 721, and the pressure instructed can be applied to the pressure roller 701 by adjusting the amount of movement of the anchor 715. This mechanism is provided at both ends of the pressure roller 701.

  In the image forming apparatus configured as described above, as soon as the power is turned on, the heat source 702 is activated to start heating the fixing roller 700, and the temperature detection unit causes the fixing roller 700 and the pressure roller 701 to be heated. Start detecting the surface temperature. When the surface temperature of the fixing roller 700 and the pressure roller 701 reaches a temperature at which an unfixed image on the transfer paper P can be fixed, copying can be started, and this is displayed on an operation panel (not shown).

  The fixing device provided in the present embodiment is pressurized at the time of printing, and other than printing and at the time of jam, the pressure is released by the pressure motor shown in FIG. The jam is easily separated. In addition, the transfer belt can be separated from the transfer belt and the photosensitive drum by a lift motor except for printing, but the transfer belt can be moved by the lift motor even during jamming. The position is separated from the photosensitive drum.

  By the way, as shown in FIG. 6, the size of the paper (recording medium) and the setting direction are detected by the combination of ON / OFF of a plurality of push switches 401 in the position of the size lever 400 in the tray. The paper fed from the duplex unit 40, the first tray (paper feed unit) 50, and the second tray (paper feed unit) 51 is conveyed upward by the vertical conveyance unit 60, and the third tray 310, the fourth tray The sheets fed from the tray 320 and the fifth tray 330 are transported upward by the vertical transport unit 340 and the vertical transport unit 60.

Then, after a predetermined time after the leading edge of the sheet is detected by the registration sensor 52, the sheet hits the registration roller 53 and temporarily stops, and is conveyed by the registration roller 53 in synchronization with the sub-scanning effective period signal (FGATE). The toner image on the body 30 is transferred. Next, the sheet is separated from the photoreceptor 30 and then conveyed by the conveying device 54, and an image is formed by the fixing device 55. The sheet after fixing is discharged to the discharge tray 200 by the switching claw 57 and the discharge roller 56 during single-sided printing and after double-sided printing.
In this example, the registration roller 53, the cradle 2, the conveyance device 54, the fixing device 55, the paper discharge roller 56, and the like constitute a horizontal conveyance unit.

  On the other hand, the paper after the front surface printing at the time of double-sided printing is guided to the reverse conveyance path 41 by the switching claw 57, the paper is switched back by the reverse conveyance roller, the paper is reversed, and the double-sided refeed conveyance path 44 is transferred. Be transported. The paper conveyed to the double-sided conveyance path is sent to the vertical conveyance unit 60 to form an image on the back surface.

  FIG. 7 is a block diagram showing the control system of this digital copying machine. In the figure, a controller 501 performs overall system control, printer data reception management, and file management. The main controller 504 is a part responsible for various controls relating to image formation, and performs paper feeding, conveyance, fixing, duplex printing, process control, paper conveyance timing control, and the like. The operation unit controller 500 performs liquid crystal display and various LED display controls and various key input controls, and the image processing controller 502 performs image control, scanner reading control, and writing control. The ADF controller 503 controls the automatic document feeder 100, and the FAX controller 505 manages FAX transmission / reception and file management.

FIG. 8 is a block diagram showing an image processing circuit of this digital copying machine.
The document 600 on the contact glass 10 is illuminated by the exposure lamp 11 and the reflected light is read by the color CCD 16. Next, the analog image signal separated into R, G, and B by the color CCD 16 is amplified by the signal processing circuit 601 and corrected for light amount, converted into a digital image signal by the AD converter 602, and shading correction by the shading correction circuit 603. And sent to the image processing unit 604.

  The image processing unit 604 performs image quality processing such as MTF correction, γ correction, black image generation, color image generation, binary processing, and multi-value processing, and outputs black data and color data to the selector 605. In the selector 605, the destination of the image signal is switched to the scaling unit 606 or the image memory controller 608. The image signal that has passed through the scaling unit 606 is enlarged / reduced in accordance with the scaling factor and sent to the writing unit 607. The image memory controller 608 and the selector 605 are configured to be able to input and output image signals in both directions. Further, a CPU 609 for setting the image memory controller 608 and the like and controlling the reading unit and the writing unit, and a ROM 610 and a RAM 611 for storing programs and data thereof are provided. Further, the CPU 609 can write and read data in the image memory 612 via the memory controller 608.

  The image sent to the image memory controller 608 as a document image is sent to the image memory 612 after the image data is compressed by an image compression device in the image memory controller 608. By performing image compression, a limited image memory can be used effectively. Further, since a large amount of original image data can be stored at a time, the stored original image data can be output in page order. In this case, when the image is output, the data in the image memory 612 is output while being sequentially expanded by the expansion device in the memory controller 608.

On the other hand, at the time of FAX transmission, the black data is transferred to the FAX image memory 613 by the selector 605. At the time of FAX reception, the received data is demodulated and expanded from the line, and is expanded in the FAX image memory 613 and then sent to the writing unit 607 by the selector 605.
Further, when the printer data is received, the data is expanded in the printer image memory 614 and then sent to the writing unit 607 by the selector 605. The ROM 610 and the RAM 611 are appropriately used via the image memory controller 608 during image processing.

The main body of the horizontal conveyance unit T of this embodiment is positioned on the main body side plate (not shown) in FIGS. 9A and 9B, and the fixing unit mounted on the horizontal conveyance unit T is the horizontal conveyance unit T. On the other hand, positioning in the direction perpendicular to the transport direction is positioned at C and D in the figure. However, it is not positioned in the transport direction, and when the lateral transport unit T is mounted on the apparatus main body 1, it is positioned on the side plate of the apparatus main body 1 by the positioning pins E and F.
In this lateral transport unit T, a structure that supports each unit such as a developing unit, a transport guide that guides paper between the units, and the like are formed by integral molding with resin. Various conveyance rollers, a transfer belt unit, a fixing unit, a duplex unit and the like are mounted, and can be pulled out from the apparatus main body 1 at right angles to the conveyance direction by slide rails SL1 and SL2 which are integrally attached to the left and right.

  FIG. 10 is a simplified diagram showing a state in which the red developing unit 33 is set in the apparatus main body 1. When the red developing unit 33 is set in the apparatus main body 1, the position thereof is determined by the pins provided in the apparatus main body 1. However, it is supported by positioning pins provided on the main body side in the same manner as the main body side support base 3 provided on the apparatus main body 1. Usually, the gap t between the red developing unit 33 and the cradle 2 is within 5 mm, preferably 2 to 3 mm. When the red developing unit 33 is pulled out to the front side of the apparatus main body 1 from this state, the left side of the red developing unit 33 is inclined downward, and a pin (not shown) provided in the red developing unit 33 is formed on the apparatus main body 1 side. In this configuration, the red developing unit 33 is supported by coming out of the positioning hole and in contact with the cradle 2. Thereafter, as shown in FIG. 11, until the red developing unit 33 is pulled out, the top of the cradle 2 is stably pulled out to the near side.

  As shown in FIGS. 12 and 13, the conveyance guide plate 4 of the pair of registration rollers 53 forming a part of the horizontal conveyance unit T is applied with pressure to apply pressure to the driven roller 53b of the registration roller 53. A pressure arm 6 and a pressure spring 7 are provided as a pressure mechanism. At this time, since the fulcrum of the pressure arm 6 is provided with the standing surface 8 on the conveyance guide plate 4, even if a reinforcing member is not newly installed on the conveyance guide plate 4, deflection due to the pressure or the weight of the conveyance guide plate itself is caused. Thus, the conveyance guide plate 4 is not deformed. Therefore, it is not necessary to attach a reinforcing member to the conveyance guide plate 4 separately.

  As shown in FIG. 14, in the digital copying machine of this example, an image forming unit such as the photosensitive member 30, the black developing unit 32, and the red developing unit 33 is disposed above the registration roller 53b. For this reason, when the digital copying machine is operated for a long period of time, the registration roller 53b may be contaminated by dust P such as toner, and the contamination may adhere to the recording paper and cause image defects. Therefore, by installing the cradle 2 so as to cover the registration rollers 53b, it is possible to prevent the registration rollers 53 from being contaminated by dust P generated from an image forming unit or the like positioned above the transport unit T.

1 is a schematic sectional view of a digital copying machine as an example of an image forming apparatus of the present invention. FIG. 2 is a partial perspective view of the digital copying machine of FIG. 1 with an automatic document feeder open. It is a figure which shows arrangement | positioning of the document size detection sensor with which the contact glass of FIG. 2 is equipped. FIG. 4 is a detailed explanatory diagram of the detection sensor of FIG. 3. FIG. 2 is an exploded perspective view of a fixing device of the digital copying machine of FIG. 1. FIG. 2 is a perspective view of a tray provided in the digital copying machine of FIG. 1. FIG. 2 is a control block diagram of the digital copying machine of FIG. 1. FIG. 2 is an image processing circuit block diagram of the digital copying machine of FIG. 1. FIG. 2 is a schematic cross-sectional view of a horizontal conveyance unit provided in the digital copying machine apparatus main body of FIG. 1. FIG. 2 is a diagram showing a state where a red developing unit is set in the digital copying machine main body of FIG. 1. It is the perspective view which showed a mode that the red developing unit of FIG. 10 was pulled out. FIG. 11 is a transverse sectional view of a cradle provided in the transverse conveyance unit of FIG. 10. It is a longitudinal cross-sectional view of the cradle with which the horizontal conveyance unit of FIG. 10 is equipped. FIG. 4 is a diagram showing a state where a resist roller is prevented from being soiled by a receiving platform due to dust such as toner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Receiving stand 3 Support stand 4 Conveyance guide plate 8 Standing surface 33 Red developing unit (developing unit)
50 First tray (paper feeder)
51 Second tray (paper feeder)
53 Registration roller 60, 340 Vertical conveyance unit 310 Third tray (paper feeding unit)
320 4th tray (paper feeder)
330 5th tray (paper feeder)
T Horizontal transport unit t Clearance

Claims (3)

In an image forming apparatus for forming an image by feeding a recording medium conveyed by a vertical conveyance unit from a sheet feeding unit to an image carrier through a registration roller,
An image forming apparatus, wherein the developing unit is provided so as to be capable of being pulled out with respect to the lateral transport unit, and a receiving base for stably pulling out the developing unit is provided on the lateral transport unit. The image forming apparatus according to claim 1, wherein the cradle is formed to cover the registration roller. The image forming apparatus according to claim 1, wherein the cradle is provided with a standing surface for reinforcement.

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