JP2005345550A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To discharge heat well from a polygon motor and to effectively use the heat in an image forming apparatus. <P>SOLUTION: The image forming apparatus is provided with image forming units 23 to 26 provided with photoreceptor drums 31 on which toner images are formed, an LSU22 carrying out exposure on the photoreceptor drums according to image data and a paper supplying cassette 21 on which recording paper is placed and supplying the recording paper. The LSU is provided with at least the polygon mirror 22b carrying out optical scanning on the photoreceptor drums and the polygon motor 22k rotating and driving the polygon mirror. Then, toner images formed by the image forming units are transferred to the recording paper supplied from the paper supplying cassette. The LSU is placed on a bottom side of the image forming units, the paper supplying cassette is installed on the bottom side of the LSU, a heat discharging member 41 discharging the heat from the polygon motor is provided, the polygon motor is installed on one end side of the heat discharging member and the other end side of the heat discharging member exists extended in the paper supplying cassette. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, and more particularly to an image forming apparatus including a heat radiating member for radiating heat from a scanning exposure apparatus.

  In general, an image forming apparatus such as a copying machine has a scanning exposure device (laser scanner unit: LSU) that scans and exposes a photosensitive drum as an image carrier in accordance with image data. Contains a rotary polygon mirror (polygon mirror), a polygon motor, a reflection mirror, and the like.

  The laser light from the laser light source is deflected by a polygon mirror and guided to the photosensitive drum by a reflection mirror to scan the photosensitive drum. The polygon mirror is driven by a polygon motor, and if the performance of the image forming apparatus is improved and the resolution is improved, the rotation speed of the polygon motor must be increased unavoidably. Must be rotated at high speed. As a result, the power consumption of the polygon motor increases and the amount of heat generated from the polygon motor increases.

  For this reason, heat is dissipated to the outside by providing heat radiation fins, etc. to the polygon motor, and furthermore, the optical box that houses the polygon motor is made of aluminum with high thermal conductivity to dissipate heat. Some have been improved (see Patent Document 1).

  In addition, there is a container that accommodates the polygon mirror and its drive circuit in which heat dissipation is improved by using a material having high thermal conductivity to reduce the wall thickness. Alternatively, all of it is made of magnesium, and due to the low specific gravity of magnesium, the natural frequency of the housing will not be lower than when aluminum is used even if the wall thickness is reduced, improving thermal conductivity (See Patent Document 2).

  In addition, a steel plate for heat absorption is joined to the back surface of the metal substrate on which the polygon motor is mounted, and a part of the steel plate is led out of the optical box on which the metal substrate is disposed, A heat conductive adhesive material or a conductive adhesive material is interposed between the heat absorption plate and the IC package for driving the motor, and a part of the heat absorption plate is led out of the optical box. There is one in which a heat conductive adhesive material is interposed between the two to perform heat dissipation.

JP 2001-142023 (page 3, FIGS. 1 to 3) Japanese Patent Laid-Open No. 11-326813 (pages 4 to 6, FIGS. 1 to 3) Japanese Patent Laid-Open No. 11-242177 (pages 3 to 4, FIGS. 1 to 6)

  In the conventional image forming apparatus, although a method for radiating the heat generated from the polygon motor is shown, the heat from the polygon motor is simply radiated well, and this heat is effectively utilized. There is a problem that it cannot be done.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus that can efficiently dissipate heat from a polygon motor and effectively use this heat. .

  Therefore, in order to solve such a problem, the present invention is provided with an image forming unit including an image carrier on which a toner image is formed, an exposure unit that exposes the image carrier according to image data, and a recording sheet. A sheet feeding unit that feeds the recording paper, and the exposure unit includes at least a polygon mirror that optically scans the image carrier and a polygon motor that rotationally drives the polygon mirror. In the image forming apparatus for transferring the formed toner image to the recording paper fed from the paper feeding unit, the exposure unit is disposed below the image forming unit, and the paper feeding is provided below the exposure unit. A heat dissipating member that dissipates heat from the polygon motor, the polygon motor is disposed on one end side of the heat dissipating member, and the other end side of the heat dissipating member extends into the paper feeding unit. What is characterized by A.

  Further, the present invention includes a cooling fan that cools the heat radiating member, and a control unit that drives and controls the cooling fan when the polygon motor is turned on.

  In the present invention, there may be provided a heater mode switch for setting a heater mode, and a control means for turning on the polygon motor without performing image formation when the heater mode is set by the heater mode switch. In this case, a temperature sensor mounted on the other end side of the heat radiating member is further provided, and the control means controls the polygon motor on and off according to the temperature detected by the temperature sensor. May be.

  As described above, in the image forming apparatus of the present invention, the exposure unit is disposed below the image forming unit, the paper feeding unit is disposed below the exposure unit, and the heat radiating member that radiates heat from the polygon motor. Equipped with a polygon motor on one end side of the heat radiating member, and the other end side of the heat radiating member extends into the paper feed unit, so that not only can the heat from the polygon motor be radiated by the heat radiating member, There is an effect that it is possible to keep the recording sheets stacked in the sheet feeding unit by heat radiation from the heat radiation member.

  In the present invention, since the cooling fan for cooling the heat radiating member is provided and the cooling fan is driven and controlled when the polygon motor is turned on, the heat from the polygon motor can be radiated well. .

  In the present invention, when the heater mode is set, the polygon motor is turned on without image formation, and the polygon motor is controlled to be turned on / off according to the temperature detected by the temperature sensor. If the mode is set, there is an effect that condensation does not occur in the sheet feeding unit as a result of keeping the sheet feeding unit by heat radiated from the heat radiating member without providing a separate heat retaining heater.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  Referring to FIG. 1, FIG. 1 is a cross-sectional view showing an image forming apparatus according to a first embodiment of the present invention as a so-called tandem type color copying machine. 12 is arranged. In accordance with the image data obtained by reading the image on the document by the document reader 12, the photosensitive drum as the image carrier is exposed as will be described later.

  In the illustrated copying machine, a paper discharge space 13 in which paper after image formation is discharged is defined between the document reading device 12 and the device housing 11. A sheet feeding cassette 21, a laser scanner unit (LSU) 22, color image forming units 23 to 26, and an intermediate transfer belt 27 as an intermediate transfer member are sequentially arranged. Specifically, the intermediate transfer belt 27 is stretched around a driving roller 27a, a driven roller 27b, and the like, and is rotationally driven in a direction indicated by a solid line arrow. The intermediate transfer belt 27 is conveyed below the intermediate transfer belt 27. For example, four image forming units 23 to 26 of yellow (Y), magenta (M), cyan (C), and black (BK) are arranged in parallel along the direction.

  The image forming units 23 to 26 have the same configuration. When attention is paid to the image forming unit 23, the image forming unit 23 includes a photosensitive drum 31 and a charger that uniformly charges the surface of the photosensitive drum 31. 32, a developing unit 33 for developing the electrostatic latent image on the photosensitive drum 31, and a cleaning device 34 for removing the toner remaining on the photosensitive drum 31.

  An LSU 22 is disposed below the image forming units 23 to 26. The LSU 22 has an LSU casing 22a. In the LSU casing 22a, a polygon mirror 22b, an imaging lens 22c, and a reflection mirror are provided. 22d to 22j are arranged, and a polygon motor 22k is connected to the central axis of the polygon mirror 22b.

  As illustrated, the polygon motor 22k is positioned below the polygon mirror 22b, and the polygon motor 22k is positioned upstream of the image forming unit 23 in the transport direction of the intermediate transfer belt 27. The polygon motor 22k is placed on a heat radiating member (for example, made of aluminum) 41 having a good thermal conductivity. That is, the heat radiating member 41 is provided with a placing portion 41a, and a polygon is placed on the placing portion 41a. While the motor 22k is mounted, the mounting portion 41a is fixed to the inner bottom surface of the LSU casing 22a.

  As shown in the figure, a slit 221 is formed on the bottom surface of the LSU casing 22a, and the heat radiation member 41 is led out of the LSU casing 22a through the slit 221. That is, the heat radiating member 41 has an orthogonal part 41b that extends downward perpendicularly to the mounting part 41a and an extending part 41c that is connected to the orthogonal part 41b and extends parallel to the mounting part 41a. The part 41b is led out of the LSU casing 22a from the slit 221, and the extending part 41c extends to the downstream side in the transport direction of the intermediate transfer belt 27 below the LSU casing 22a in a state parallel to the mounting part 41a. doing.

  As shown in the drawing, a sheet feeding cassette 21 is positioned below the LSU casing 22a, and the sheet feeding cassette 21 can be pulled out from the apparatus casing 11 in the direction indicated by the broken line arrow in the figure. (In other words, the intermediate transfer belt 27 can be pulled out downstream in the conveying direction). The paper feed cassette 21 is provided with a paper placement plate 21a, a pickup roller 21b, and a paper feed roller 21c, and the sheets stacked on the paper placement plate 21a are picked up one by one by the pickup roller 21b and fed. The sheet is sent to the sheet conveyance path 42 by the roller 21c.

  As shown in the drawing, the above-described extending portion 41c is positioned on the upstream end of the sheet placing plate 21a in the sheet conveying direction, and a temperature sensor 43 is mounted on the extending portion 41c. Referring also to FIG. 2, a cooling fan 44 is disposed in the apparatus housing 11, and this cooling fan 44 is positioned on the right side of the LSU housing 22 a in FIG. 1 (that is, the cooling fan 44 is In the conveyance direction of the intermediate transfer belt 27, the intermediate transfer belt 27 is positioned upstream of the LSU casing 22a). Further, as shown in FIGS. 1 and 2, the size of the cooling fan 44 has an area that can cover at least the polygon mirror 22 b, the polygon motor 22 k, and the heat radiation member 41. Thus, air is sent to the LSU casing 22a and the heat radiating member 41 (particularly, the extending portion 41c), and the heat radiating member 41 and the like are cooled.

  In the illustrated copying machine, when copying, an image on a document is read by the document reading device 12, and semiconductor lasers of four colors (Y, M, C, BK) are modulated according to the image data. The laser light emitted from these semiconductor lasers is applied to the polygon mirror 22b. The polygon mirror 22b is rotationally driven by a polygon motor 22k, and laser light is deflected and scanned by the polygon mirror 22b. The laser beam deflected and scanned by the polygon mirror 22b is scanned and exposed from below onto the photosensitive drum 31 for each color via the imaging lens 22c and the reflection mirror mirrors 22d to 22j.

  That is, the surfaces of the photosensitive drums 31 of the corresponding image forming units 23 to 26 are scanned and exposed by the laser light emitted according to the image data of each color of Y, M, C, and BK, and the respective photosensitive members. An electrostatic latent image is formed on the drum 31. The electrostatic latent image formed on the photosensitive drum 31 is developed as a toner image of each color of Y, M, C, and BK by the developing device 33.

  The Y, M, C, and BK toner images respectively formed on the photosensitive drums 31 of the image forming units 23 to 26 are sequentially transferred to the intermediate transfer belt 27 by a primary transfer roller (not shown). As a result, a color toner image is formed on the intermediate transfer belt 27. As shown in FIG. 1, the driven roller 27 b faces the secondary transfer roller 45 with the intermediate transfer belt 27 interposed therebetween, so that the sheet is fed from the sheet feeding cassette 21 via the sheet conveyance path 42 to the intermediate transfer belt 27 and the secondary transfer roller 42. The color toner image on the intermediate transfer belt 27 is transferred to a sheet as a secondary transfer image by the secondary transfer roller 45 by being conveyed to a nip portion with the transfer roller 45.

  Thereafter, the sheet is sent to the fixing unit 47 through the sheet conveyance path 46, where the secondary transfer image on the sheet is fixed, and the sheet passes through the sheet discharge path 48 and is discharged by the discharge roller 49. The paper is discharged.

  The polygon motor 22k generates heat when driven, but the heat from the polygon motor 22k is transferred to the heat radiating member 41 and radiated from the heat radiating member 41. As described above, since the extending portion 41c is led out of the LSU casing 22a, the heat from the polygon motor 22k does not flow into the LSU casing 22a, and the heat from the polygon motor 22k is radiated well. can do. Furthermore, if the cooling fan 44 is driven, the heat radiating member 41 (particularly, the extending portion 41c) is cooled, so that better heat dissipation can be performed.

  By the way, the paper on the paper cassette absorbs moisture according to the atmospheric humidity (environmental humidity) and the like, and if the amount of moisture in the paper increases, when the color toner image is transferred onto the paper, good transfer may not be performed. . Furthermore, in a cold region or the like, condensation may occur in the paper feed cassette and the amount of water in the paper may increase. In order to prevent such moisture absorption of the paper, a heat insulation heater is arranged in the vicinity of the paper feed cassette. However, if a heat insulation heater is provided, the cost and power consumption of the heat insulation heater are only increased. There must be enough space for installing the insulation heater.

  Therefore, in the first embodiment, as described above, the extending portion 41 c of the heat radiating member 41 is positioned on the paper placement plate 21 a of the paper feed cassette 21, and the heat radiating from the heat radiating member 41 is performed on the paper feed cassette 21. The air temperature is raised to prevent the paper from absorbing moisture. Thus, if the heat radiating member 41 is used instead of the heat retaining heater, the heat retaining heater becomes unnecessary, which is advantageous in terms of cost and space.

  Here, heat dissipation and moisture absorption prevention control will be described. First, referring to FIG. 3, when image formation is performed, when the power is turned on (power on: step S1), the control device (not shown) turns on the polygon motor 22k and the cooling fan 44. (Step S2) Copying is performed as described above (Step S3). When copying is completed (step S4), the control device turns off the polygon motor 22k and the cooling fan 44 (step S5), and then the power is turned off (power OFF: step S6).

  Thus, when copying, the cooling fan 44 is driven, heat is radiated from the heat radiation member 41 from the polygon motor 22k, and the heat radiation member 41 is cooled by the cooling fan 44. During the 22k drive, that is, when the copying machine is operating, heat can be radiated satisfactorily.

  Next, referring to FIG. 4, when the copying machine is not in operation, particularly when the main power of the copying machine is turned off at night or the like, it is provided on the operation panel (not shown) in advance. When the heater mode button is turned on (heater mode ON: step P1), the control device turns on the polygon motor 22k (step P2: only the polygon motor 22k is turned on at this time. The temperature measured by the temperature sensor 43 is read (temperature sensor ON: step P3).

  Since the temperature sensor 43 is mounted on the extending portion 41c of the heat radiating member 41, the temperature of the heat radiating member 41 is measured, and the control device sets a temperature regulation value (for example, 25 ° C.) at which the measured temperature is prescribed in advance. Then, it is determined whether or not the temperature is equal to or higher than the temperature at which the paper cassette 21 does not cause condensation (step P4). If the measured temperature is equal to or higher than the temperature regulation value, the polygon motor 22k is turned off (step P5), and the heater mode is set. It is determined whether or not the button is turned off (step P6). When the heater mode button is turned off, the control device ends the heater mode. On the other hand, if the heater mode button is on, the control device returns to step P4.

  On the other hand, if the measured temperature is less than the temperature regulation value, the control device continues to drive the polygon motor 22k (step P7), determines whether or not the heater mode button is turned off (step P8), and the heater When the mode button is turned off, the control device turns off the polygon motor 22k (step P9) and ends the heater mode. On the other hand, if the heater mode button is on, the control device returns to step P4.

  In this way, when the main power of the copying machine such as night is turned off, when the heater mode is entered, the polygon motor 22k is driven and controlled, so that heat from the polygon motor 22k passes through the heat radiating member 41. Heat is dissipated to the paper feed cassette 21, and the inside of the paper feed cassette 21 is warmed up, so that no dew condensation or the like occurs in the paper feed cassette 21, and the paper does not absorb moisture. As a result, the next morning, when the first copy is made by the copying machine, a good image can be formed.

  An exposure unit is placed below the image forming unit, a paper feed unit is placed below the exposure unit, and a heat dissipation member that dissipates heat from the polygon motor is provided, and a polygon motor is mounted on one end of the heat dissipation member. Since the other end side of the heat radiating member extends into the paper feeding unit, the heat from the polygon motor can be radiated by the heat radiating member, and the recording paper loaded in the paper feeding unit by the heat radiated from the heat radiating member As a result, the image forming apparatus can be applied not only to a copying machine but also to an image forming apparatus such as a printer or a facsimile machine.

1 is a diagram schematically showing a first embodiment of an image forming apparatus according to the present invention by breaking it. FIG. 2 is a diagram schematically illustrating the image forming apparatus according to the present invention from a rear side with a part thereof broken. 2 is a flowchart for explaining on / off control of a polygon motor and a cooling fan during copying in the image forming apparatus shown in FIG. 1. 3 is a flowchart for explaining on / off control of a polygon motor in a heater mode in the image forming apparatus shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Apparatus housing | casing 12 Document reader 13 Paper discharge space 21 Paper feed cassette 22 Laser scanner unit (LSU)
23 to 26 Image forming unit 27 Intermediate transfer belt 31 Photosensitive drum 32 Charger 33 Developer 34 Cleaning device 22a LSU housing 22b Polygon mirror 22c Imaging lens 22d to 22j Reflection mirror 22k Polygon motor 41 Heat radiation member 42, 46 Paper transport Path 43 Temperature sensor 44 Cooling fan 45 Secondary transfer roller 47 Fixing unit

Claims (4)

An image forming unit including an image carrier on which a toner image is formed, an exposure unit that exposes the image carrier according to image data, and a paper feeding unit on which a recording paper is placed and feeds the recording paper And the exposure unit includes at least a polygon mirror that optically scans the image carrier and a polygon motor that rotationally drives the polygon mirror, and supplies a toner image formed by the image forming unit from the sheet feeding unit. In an image forming apparatus for transferring to a paper sheet,
The exposure unit is disposed below the image forming unit, and the paper feeding unit is disposed below the exposure unit,
A heat dissipating member for dissipating heat from the polygon motor;
An image forming apparatus, wherein the polygon motor is disposed on one end side of the heat radiating member, and the other end side of the heat radiating member extends into the paper feeding unit. A cooling fan for cooling the heat dissipation member;
The image forming apparatus according to claim 1, further comprising a control unit that drives and controls the cooling fan when the polygon motor is turned on. A heater mode switch for setting the heater mode;
2. The image forming apparatus according to claim 1, further comprising a control unit that turns on the polygon motor without performing image formation when the heater mode is set by the heater mode switch. A temperature sensor mounted on the other end of the heat dissipating member;
The image forming apparatus according to claim 3, wherein the control unit performs on / off control of the polygon motor in accordance with a temperature detected by the temperature sensor.

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