JP5589456B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a facsimile machine, and a printer, and in particular, air is supplied from a blower fan and a blow duct to a gap between an image forming unit installed in the image forming apparatus and an optical scanning device. The present invention relates to a technology that can be supplied to increase the cooling efficiency of the image forming unit.

  In an electrophotographic image forming apparatus, the problem of cooling to an overcrowded space with respect to an increasing amount of heat generation has become an item that cannot be ignored with the increase in device speed (linear speed increase) and device size reduction. In particular, there is a concern about a temperature increase due to self-heating of the image forming unit, and a more efficient cooling method for the developing unit is required. Japanese Patent Application Laid-Open No. 2008-33135 (Patent Document 1) related to the applicant's proposal suppresses the temperature rise of the optical scanning device or the image forming apparatus including the optical scanning device in view of the above situation. For this purpose, an air flow path is formed in the direction of air flow by the intake fan and the exhaust fan in the optical scanning device.

  That is, in Patent Document 1, as shown in FIG. 8, an intake fan is provided on the left side of the printer and an exhaust fan is provided on the right side so as to face each other, and an air flow passage is formed at the bottom of the outer peripheral surface of the casing. Further, both side walls forming the air flow passage are provided substantially in parallel with the air flow, one end of the flow passage is opposed to the intake fan, and the other end is opposed to the exhaust fan. With this configuration, the air sucked by the intake fan from the outside of the apparatus flows into the flow path, moves in the flow path, and is discharged outside the apparatus by the exhaust fan. However, in the technique of Patent Document 1 in which air is supplied to the optical scanning device using an intake fan and an exhaust fan, the process cartridge that is an image forming unit is arranged at a position separated vertically below the optical scanning device. Because of this, it was difficult to cool down to the image forming unit.

  Japanese Patent Application Laid-Open No. 2004-294949 (Patent Document 2) discloses a technique for supplying air to an image forming unit and cooling it. This cools the heat generating part of the optical scanning device with the air flowing through the air circulation space formed between the optical scanning device and the component on which the device is placed, and provides an opening for passing the air to the developing device. This also cools the developing device. However, even with the technique of Patent Document 2, a certain level of results can be expected. However, the fan that supplies air and the air circulation space are separated from each other, and the air supplied from the fan is used as the air circulation space. However, it was difficult to feed effectively.

  Therefore, a technique such as Japanese Patent No. 3888022 (Patent Document 3) in which an intake duct is connected to an intake fan and the tip of the duct is connected to an image forming unit that is an image forming unit has been proposed. . However, as shown in detail in FIG. 5, the intake duct disclosed herein is formed in a substantially triangular shape with a long plan view, and the opening area is smaller on the side opposite to the intake fan than on the intake fan side. In this way, the upper end portion is opened so as to supply air from the front side in the longitudinal direction of each image forming unit toward the back side.

  However, in order to install such a duct on one side of each image forming unit, a certain amount of space is required on the installation side, which is a technique that is difficult to adopt for an image forming apparatus that is aimed at downsizing. In addition, the shape of the air duct is merely that the planar shape as described above is connected in an elongated triangular shape, and the intake fan itself is also specially devised in its casing shape when connected to the duct. For this reason, the pressure loss of the duct for sending air from the intake fan is large, and it is difficult to cool the image forming units that are image forming units, and the problem of poor cooling efficiency cannot be solved.

  Accordingly, the present invention solves the above-described conventional problems, and an object thereof is to reduce the pressure loss of the duct in an image forming apparatus that supplies air to the image forming unit using a blower fan and a blower duct. In order to improve the cooling efficiency of the image forming unit.

In order to achieve the above object, an invention according to claim 1 is directed to an image forming unit, an optical scanning device disposed opposite to the image forming unit with a gap, a blower fan for supplying air, An image forming apparatus comprising a blower duct connected to a blower fan and sending air from the blower fan to a gap between the image forming unit and the optical scanning device , the blower fan having a ventilation path in a casing , vent air passages, together with the impeller therein is arranged, it is formed in a venturi shape whose diameter increases toward the portion where the inner surface is opposed to the impeller on both end portions of the air passage, the air duct, the light inner surface shape of the cross section perpendicular to the main scanning direction of the scanning device has a body formed gradually reduced in diameter to a funnel shape toward from the blower fan side to the gap side, said body, the blowing fan side While end, has a large径口be stepped without connecting the outer and inner surface having a maximum diameter of venturi shape formed on the inner surface of the air passage, the ends of the gap side, the blowing fan From which the air flowing into the main body through the large-diameter opening is sent to the gap, and the outlet is formed in a long and flat rectangular shape with a height corresponding to the gap , It is arranged at an intermediate position in the height direction of the main body formed in a funnel shape.

A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the air ducts are provided symmetrically in the vicinity of both ends in the main scanning direction of the optical scanning device in the main body of the image forming apparatus. The pair of air ducts are characterized in that the inner surface on the central side in the main scanning direction among the inner surfaces facing the longitudinal direction of the outlet is formed on an inclined surface inclined toward the central portion in the main scanning direction. To do.

The present invention is as described above. According to the invention described in claim 1 or 2, the blower fan has a ventilation path in the casing, and the ventilation path has an impeller disposed therein. In addition, the inner surface is formed in a venturi shape whose diameter increases from the portion facing the impeller toward both ends of the ventilation path, and the air duct has an inner surface shape in a cross section orthogonal to the main scanning direction of the optical scanning device. has a body formed in a funnel shape gradually reduced in diameter toward the gap side from the blower fan side, the body, the ends of the blower fan side, formed on the inner surface of the air passage while that is a large径口be stepped without connecting the outer and inner surface having a maximum diameter of the venturi-shaped, the ends of the gap side, air flowing from said the blower fan through the large径口into body Blowing into the gap Has a mouth, the outlet is formed in a rectangular shape cheesy elongated height commensurate with the gap, it is disposed in an intermediate position in the height direction of the body formed in the funnel-shaped Therefore, air can be supplied to the image forming unit of the image forming apparatus using the blower fan and the air duct without increasing the pressure loss, and the cooling efficiency of the image forming unit can be improved.

1 is a cross-sectional view illustrating an overall configuration outline of a color printer that is an example of an image forming apparatus according to the present invention. The ventilation fan in the above is shown, (A) is the front view, (B) is a side sectional view. It is an expanded sectional view showing the flow of the air in the ventilation duct connected to the same ventilation fan. It is the perspective view seen from the blower outlet side of the ventilation duct connected to the ventilation fan same as the above. The connection structure of a ventilation fan and a ventilation duct same as the above is shown, (A) is the center sectional drawing, (B) is a cross-sectional perspective view. The blast | air duct which shows the same as the above is shown, (A) is the top view, (B) is sectional drawing showing the flow of the air in a duct. It is the cross-sectional top view which showed typically the flow of the air sent from a ventilation fan same as the above with the set space etc. of the image formation unit. It is a perspective view which shows an example of an optical scanning device same as the above.

<Configuration of image forming apparatus>
Hereinafter, an image forming apparatus to which the present invention is applied will be described with reference to the drawings. The present invention is characterized in that the shape of the blower fan that supplies air for cooling to the image forming unit that is the image forming unit of the image forming apparatus and the shape of the blower duct are connected to match the venturi shape of the blower fan. ing.

  FIG. 1 is a diagram illustrating an overall configuration outline of a color printer 100 which is an example of an image forming apparatus. The color printer 100 shown in this figure can form a full-color image using a tandem method. In the color printer 100, an image forming unit 10 (Y, M, C, K) serving as four process cartridges is disposed in a substantially central portion of the apparatus main body 101. Each of the image forming units 10 (Y, M, C, K) is arranged in parallel along the lower traveling side of the intermediate transfer belt 56 serving as an intermediate transfer member. The intermediate transfer belt 56 wound around the plurality of support rollers 52 to 55 is driven to run counterclockwise in the figure as indicated by an arrow A. Inside the intermediate transfer belt 56, a transfer roller 5 (Y as a primary transfer unit) is provided so as to face the photosensitive drum 1 (Y, M, C, K) serving as an image carrier included in each image forming unit 10. , M, C, K). A belt cleaning unit 57 for cleaning the intermediate transfer belt 56 is disposed outside the left support roller 55 around which the intermediate transfer belt 56 is wound.

  Each image forming unit 10 has the same configuration except for the color of the toner to be handled, and includes a photosensitive drum 1 (Y, M, C, K). Although not shown in detail, a well-known charging means, developing device, lubricant application device, cleaning device, and the like are arranged around the photosensitive drum 1. Each image forming unit 10 is detachably attached to the apparatus main body 101 as a process cartridge.

  The developing device of each image forming unit 10 is provided with a developing sleeve at a position facing the photosensitive drum 1 (Y, M, C, K). Two screws are provided below the developing sleeve. The two-component developer composed of toner and magnetic carrier is regulated to a predetermined developer layer thickness by a doctor blade and is carried on the developing sleeve. Although the two-component development method has been described here, the present invention is not limited to this, and a one-component development method developing device can also be used.

  Below the tandem image forming unit in which the four image forming units 10 (Y, M, C, K) are arranged, an optical writing device 9 serving as an optical scanning device is provided with a small gap 23. As will be described later, the optical writing device 9 includes a polygon mirror, a group of mirrors, and the like and an optical housing, and applies light modulated laser light to the photosensitive drums 1 (Y, M, C, K) of the color image forming units 10. ).

  In FIG. 1, a blower fan 30 that constitutes a cooling unit is arranged on the left side of each image forming unit 10 and the optical writing device 9, and air (airflow) sucked from outside the apparatus is used as a tandem image forming unit and an optical writing device. 9 is configured to blow air through the air duct 40 in the gap 23 formed between the air and the air. Thereby, the optical writing device 9 and each image forming unit 10 (Y, M, C, K) are air-cooled by the air from the blower fan 30.

  At the bottom of the apparatus main body 101, a paper feed tray 20 is disposed on which sheets to be recording materials are stacked. Above the paper feed tray 20, a paper feed roller 21 that feeds the paper stacked on the paper feed tray and a separating unit (not shown) are arranged. A pair of registration rollers 22 is provided above the paper feed roller 21 (downstream in the paper conveyance direction). Above the pair of registration rollers 22, a transfer roller 61 as a secondary transfer unit is disposed opposite to a support roller (transfer counter roller) 52 via an intermediate transfer belt 56 to form a secondary transfer portion. Yes.

  A fixing device 70 is provided above the secondary transfer unit. The fixing device 70 includes a heating roller 72 and a fixing belt 71 that is stretched over the fixing roller 73, and has a configuration in which a pressure roller 74 is pressed against the fixing belt 71. The fixing device 70 fixes the sheet on which the unfixed toner image is transferred in the secondary transfer unit by heating and pressing. A paper discharge roller 91 is provided obliquely above the fixing device 70 and discharges the fixed paper onto a paper discharge tray 102 formed on the upper surface of the main body.

<Operation of Image Forming Apparatus>
An image forming operation in the color printer 100 configured as described above will be described in summary. Each photosensitive drum 1 of each image forming unit 10 (Y, M, C, K) is rotated in the clockwise direction in the figure by a driving means (not shown), and the surface of each photosensitive drum 1 is brought to a predetermined polarity by a charging means. Uniformly charged. The surface of the charged photoconductive drum 1 is irradiated with laser light from the optical writing device 9, whereby an electrostatic latent image is formed on the surface of each photoconductive drum 1. When forming a color image, the image information exposed on each photosensitive drum 1 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. The toner of each color is applied from the developing devices to the electrostatic latent image formed in this manner, and visualized as a toner image. Further, the intermediate transfer belt 56 is driven to run in the counterclockwise direction in the drawing, and in each image forming unit 10, the intermediate transfer belt 56 is moved from each photosensitive drum 1 by the action of each primary transfer roller 5 (Y, M, C, K). Each color toner image is sequentially superimposed and transferred. In this way, the intermediate transfer belt 56 carries a full-color toner image on the surface thereof.

  A single color image can be formed by using any one of the image forming units 10 (Y, M, C, K), or a two-color or three-color image can be formed. In the case of monochrome printing, image formation is performed using the black image forming unit 10K arranged on the rightmost side in FIG. 1 among the four image forming units.

  Residual toner adhering to the surface of each photosensitive drum 1 after the toner image is transferred is removed from the surface of the photosensitive drum 1 by the cleaning unit, and then the surface is subjected to the action of a static eliminator to initialize the surface potential. In preparation for the next image formation.

  On the other hand, the paper is fed from the paper feed tray 20 and sent out toward the secondary transfer position in timing with the toner image carried on the intermediate transfer belt 56 by the pair of registration rollers 22. In this embodiment, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt is applied to the secondary transfer roller 61, whereby the toner image on the surface of the intermediate transfer belt 56 is batched on the sheet. And transferred. When the sheet on which the toner image has been transferred passes through the fixing device 70, the toner image is fused and fixed to the sheet by heat and pressure. The fixed sheet is discharged to a discharge tray 102 on the upper surface of the apparatus main body 101 by a discharge roller 91.

  The residual toner on the intermediate transfer belt 56 is cleaned by a belt cleaning unit 57.

<Blower fan and fan duct>
The blower fan 30 includes a drive motor 31, an impeller portion 32, and a casing 33 as shown in an enlarged view in FIGS. By energizing, the motor 31 is driven, and the air blown by the rotation of the impeller portion 32 is increased in speed, and the air is swirled in the direction of the arrow in FIG. The inner surface of the casing 33 is formed in a flat shape so that a gap between the impeller portion 32 and the casing 33 is constant at the position where the impeller portion 32 is disposed, and expands on both the intake side and the exhaust side from the end toward the end of the casing 33. It is formed into a venturi shape.

  The inner surface shape of the blower duct 40 is connected to the venturi shape of the blower fan 30 shown in FIG. That is, the air duct 40 is formed in a large diameter opening 42 in which one end opening portion of the main body 41 is connected to the venturi-shaped maximum diameter (outer edge) portion of the exhaust side end of the casing 33 of the air blowing fan 30. The portion is formed in a long and flat rectangular outlet 43 having an appropriate height so that air can be efficiently blown into the gap 23, and the inner surface of the main body 41 between the large diameter portion 42 and the outlet 43. Is formed in a funnel-like shape from the large-diameter portion side toward the air outlet side. In other words, a main body 41 having an inner surface formed in a funnel shape, and a rectangular body 45 communicating with the inside of the main body and having an outlet 43 at the center of the main body 41 (an intermediate position in the height direction of the main body 41 in FIG. 3) Are integrally formed. Thereby, as shown in FIG. 3, the swirl flow 44 of the air generated by the rotation of the blower fan 30 can be blown out from the outlet 43 without causing a loss due to a sudden expansion or the like. Therefore, anyway, in the air duct configured with a simple R shape of the conventional fan, when the air blown from the air fan passes through the air duct, the pressure loss is large and the efficiency may be deteriorated. The duct 40 has an inner surface shape as shown in the figure, whereby the pressure loss of the duct can be reduced and the efficiency can be increased.

  Moreover, the blower outlet 43 of the blower duct 40 is formed in an expanded shape so that one side of the blower outlet 43 in the blowing length direction faces outward as is apparent from FIGS. . That is, it is formed on the surface 46 parallel to the blowing direction so that the air blown out from one side of the outlet 43 goes straight, so that the air blown out from the other side does not go straight but proceeds outward. An inclined surface 47 is formed. This is so that air in the direction of the other side surface can be blown out in a wider range among the air blown out from the blower outlet 43. In this embodiment, only the other side surface is the inclined surface 47, but if necessary, one side surface may be formed on the same inclined surface as the other side surface. May be parallel planes.

  As shown in FIG. 7, the blower fan 30 and the blower duct 40 connected as described above are provided in the space between the front side plate 111 and the rear side plate 112 that constitute the casing of the apparatus main body 101, and one of the blowers is provided. One side surface of the duct 40 is parallel to the front side plate 111, one side surface of the other air duct 40 is parallel to the rear side plate 112, and the other side surfaces of both the air ducts 40 are installed to face each other.

<Case configuration of the device body>
FIG. 7 schematically shows the flow of air (airflow) sent from the blower fan 30 together with the set space in which each image forming unit 10 (Y, M, C, K) is set. In the figure, between the front side plate 111 and the rear side plate 112 constituting the casing of the apparatus main body 101, four unit bottom plates 113 serving as unit members are disposed. Here, four unit bottom plates 113 are provided, but a single unit bottom plate may be used. The upper space of the unit bottom plate 113 is partitioned by a plurality of partition plates 114, and becomes a set space 116 (Y, M, C, K) for setting each image forming unit 10 (Y, M, C, K). ing. In FIG. 7, the black image forming unit 10K is indicated by a virtual line in the rightmost set space 116K.

  Four openings 111aY to 111aK are formed in the front side plate 111 so that each image forming unit 10 (Y, M, C, K) can be attached and detached. In addition, each unit bottom plate 113 is provided with introduction holes 115 </ b> Y to 115 </ b> K through which scanning light from the optical writing device 9 positioned below is introduced onto each photosensitive drum 1.

  Between the unit bottom plates 113 arranged above the optical writing device 9 and below each image forming unit 10 (Y, M, C, K), the front plate 111 and the rear plate 112 are front and rear as described above. A divided gap 23 is formed. The gap 23 is a long and flat space when viewed from the blower fan 30 side. The air outlet R of the air duct 40 connected to the blower fan 30 is close to the left end of the gap 23 so that the air flow R generated by the rotation of the blower fan 30 can be removed. 23, the optical writing device 9 is cooled from its upper side, and each image forming unit 10 that is a tandem image forming unit is cooled from its lower side.

  The optical writing device 9 includes a rotary polygon mirror (not shown), and an upper cover (see FIG. 5) in which heat generated from the rotary polygon mirror and its driving means is disposed on the gap 23 side via the housing of the optical writing device 9. (Not shown). Therefore, the entire optical writing device 9 can be cooled by cooling the upper cover with the airflow R of air flowing through the gap 23. The airflow R of the air sent into the gap 23 is guided into the set spaces 116Y to 116K through the introduction holes 115 provided in the unit bottom plate 113, and is heated by the developing device or the like. , M, C, K) can be cooled.

  The air sucked from the outside of the apparatus through the filter 120 of FIG. 7 is blown by the two blower fans 30 in the direction of arrow R in the drawing. As described above, the blown air has an asymmetric shape in which the blowout shape of the blowout port 43 of the blower duct 40 extends inward with one side as a parallel surface 46 and the other side as an inclined surface 47. The flow merges from the blowout side on the left side of the figure toward the downstream side on the right side of the figure, and flows uniformly from left to right. By matching the asymmetric shape of the air outlet 43 with the rotation direction of the air sent out from the blower fan 30 (= rotation direction of the fan), air can be supplied more efficiently. Therefore, the merging of the air flow R in the gap 23 is further promoted, and the cooling efficiency is improved. Reference numeral 121 denotes a CTL.

<Configuration of optical writing device>
FIG. 8 is a perspective view showing an example of an optical writing device 9 which is an optical scanning device applicable to the present invention. The optical writing device 9 shown in this figure is of a multi-beam type and includes first and second semiconductor lasers 251 and 252 constituting a multi-beam light source unit. The multi-beams emitted from the semiconductor lasers 251 and 252 are converted into parallel light beams by the collimator lenses 253 and 254, respectively, synthesized by the synthesis prism 255, and narrowed down in the sub-scanning direction by the cylinder lens 256. Subsequently, the beam reflected by the polygon mirror 257 serving as a rotating deflector passes through the fθ lens 258 and the toroidal lens 259 so that the dot pitch in the main scanning direction is equalized. The multibeam subjected to such processing is reflected by the reflecting mirror 260 and scans on the photosensitive drum 1. As a result, the print data is written.

  In addition, a synchronization detection sensor 261 is disposed outside the image area. When the synchronization detection sensor 261 detects the laser beam irradiation from the first semiconductor laser 251, the detection timing is the main scanning first line. This is a reference for the writing start position. When the synchronization detection sensor 261 detects the irradiation of the laser beam from the second semiconductor laser 252, this detection timing becomes a reference for the writing start position of the main scanning second line. This is performed for each main scanning line to align the main scanning image position.

<Action of air flow>
As described above, the air generated by the blower fan 30 that rotates as the motor 31 is driven is connected to the casing 33 of the ventilator fan 30 whose inner surface is in accordance with the venturi shape. Since the swirl flow 44 generated by the rotation of the blower fan 30 is blown out from the duct 43 through the blower duct 40 without causing a loss due to sudden expansion or the like, the pressure loss of the duct is reduced and the efficiency is improved. Can be increased. Then, the air blown from the blower outlet 43 is blown into a gap 23 formed between the optical writing device 9 and the image forming unit 10 (Y, M, C, K). The air blown into the gap 23 spreads evenly and uniformly in the space between the front side plate 111 and the rear side plate 112 constituting the housing of the apparatus main body 101 as indicated by an arrow in FIG. The apparatus 9 is cooled from the upper side, and each image forming unit 10 is cooled from the lower side. That is, the optical writing device 9 is cooled by receiving the air passing above it with the upper cover. Further, each image forming unit 10 is cooled by passing air passing through the opening 115 and entering the set space 116 (Y, M, C, K).

  Therefore, as before, air can be supplied to the image forming unit without increasing pressure loss, and the cooling efficiency of each image forming unit 10 (Y, M, C, K) can be increased. Further, not only the image forming units 10 (Y, M, C, K) but also the optical writing device 9 can be cooled. Therefore, it is effective in the tandem type image forming apparatus as in this embodiment. Further, the installation space for the blower fan 30 and the blower duct 40 does not require a large space as before, and it is possible to sufficiently cope with the downsizing of the apparatus.

  The above-described embodiment is merely a preferred example, and the detailed structure, shape, and the like of the main constituent members of the present invention are within the scope described in the claims, and different appropriate embodiments are included. Is included.

1 (Y, M, C, K) Photosensitive drum (image carrier)
9 Optical writing device (optical scanning device)
10 (Y, M, C, K) Image forming unit 23 Gap 30 Blower fan 31 Drive motor 32 Impeller portion 33 Casing 40 Blower duct 41 Main body 42 Large diameter port 43 Air outlet 44 Swirl 46 Parallel surface 47 Inclined surface 100 Color printer (Image forming device)
101 apparatus main body 111 front side plate 111aY-111aK opening 112 rear side plate 113 unit bottom plate 114 partition plate 115Y-115K introduction opening 116 (Y, M, C, K) set space

JP 2008-033135 A JP 2004-294949 A Japanese Patent No. 3888022

Claims (2)

An image forming unit, an optical scanning device disposed opposite to the image forming unit with a gap, a blower fan for supplying air, and the air from the blower fan connected to the blower fan and the light An image forming apparatus including a blower duct that is sent to a gap of a scanning device ,
The blower fan has a ventilation path in the casing. The ventilation path has an impeller disposed therein, and an inner surface of the ventilation fan expands from a portion facing the impeller toward both ends of the ventilation path. Formed into a venturi shape,
The blower duct has a main body formed in a funnel shape in which an inner surface shape of a cross section perpendicular to the main scanning direction of the optical scanning device is gradually reduced in diameter from the blower fan side toward the gap side ,
The body, while the end portion of the blower fan side, has a large径口be without any step connected in maximum diameter and becomes the outer edge and the inner surface of the venturi shape formed on the inner surface of the air passage, the gap The end on the side is a blowout port that sends air flowing into the main body from the blower fan through the large diameter port to the gap,
The outlet is an image wherein said is formed in a rectangular shape cheesy elongated height commensurate with clearance is arranged in an intermediate position in the height direction of the body formed in the funnel-shaped Forming equipment. The image forming apparatus according to claim 1 ,
The air ducts are provided symmetrically in the vicinity of both ends in the main scanning direction of the optical scanning device in the main body of the image forming apparatus, and the pair of air ducts are centered in the main scanning direction on the inner surface facing the longitudinal direction of the air outlet. An image forming apparatus characterized in that an inner surface on the part side is formed as an inclined surface that is inclined toward the central side in the main scanning direction .