JP5471273B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus.

  There are various types of image forming apparatuses for forming an image on a print medium such as paper (hereinafter, the print medium is referred to as “paper”). There is an image forming apparatus that forms an electrostatic latent image based on an image formed on a print medium and carries a developer on the latent image for image formation. As such an image forming apparatus, for example, a photosensitive member is used as an image carrier, a laser beam is irradiated to form a latent image on the photosensitive member, and a developer including toner (pigment) and a carrier is applied to the latent image by an electric field. There is an image forming apparatus that carries an image.

There is a developing device as a device for developing the image carrier with the developer in order to carry the developer on the image carrier.
FIG. 12 shows a configuration example of a conventional developing device 300.
The developing device 300 includes stirring and conveying members 305 and 306 and a developing roller 301.
The agitating / conveying members 305 and 306 have spirally connected blades (screws), and agitate the developer stored in the casing by the rotation thereof. The agitating and conveying members 305 and 306 convey the developer to the developing roller 301 side by the rotation thereof.
The developing roller 301 carries the developer conveyed by the agitating and conveying members 305 and 306 and develops it on the image carrier (photosensitive drum 351). The photosensitive drum 351 and the developing roller 301 are provided to face each other with a slight gap, and the toner contained in the developer carried on the developing roller 301 is between the photosensitive drum 351 and the developing roller 301. The formed electric field flies from the developing roller to the photosensitive drum and is carried on the photosensitive drum 351.

In such a developing device 300, the developer continues to be agitated by the agitating / conveying members 305 and 306, and thus keeps rubbing against each part of the developing device such as the agitating / conveying members 305 and 306 and the casing 322. The developer is heated by frictional heat generated by such friction. The developer also generates frictional heat due to friction between the conveyed developers, and is heated. That is, in the developing device 300, the developer is heated by friction.
When the developer has heat, there may be a problem that the toner is melted and fixed (fused) in the developing device. The fused toner may interfere with the transport of the developer or cause unevenness in the developer carried on the developing roller, resulting in a reduction in image quality.

  Therefore, a cooling device for cooling the developer in the developing device 300 is known. As a developer cooling device provided in the developing device, for example, there is a configuration for cooling the bottom portion of the casing 322 (for example, Patent Document 1). In addition, the developer regulating member 331 that adjusts the amount of developer carried on the developing roller 301 to a predetermined amount before the toner is developed from the developing roller 301 to the photosensitive drum 351 is made of a metal having a high thermal conductivity, or the like. There is a configuration in which the member 332 is brought into contact and the heat of the developer is taken away via the developer regulating member 331 (for example, Patent Document 2 and Patent Document 3).

JP 2002-365888 A JP 2004-109868 A JP 2005-62683 A

However, in the cooling device for cooling the developer according to Patent Documents 1 to 3 described above, the developer is not sufficiently cooled.
For example, in the configuration in which the bottom portion of the casing 322 is cooled as in Patent Document 1, the developer present in the gap between the stirring and conveying members 305 and 306 and the casing 322 is intensively cooled. The developer at the position remains in the gap between the stirring and conveying members 305 and 306 and the casing 322 and is not conveyed to the developing roller 301. On the other hand, the developer which is not or hardly received the cooling from the casing 322 and is stirred and transported by the stirring transport members 305 and 306 is transported to the developing roller 301 without being cooled. For this reason, the developer conveyed to the developing roller 301 is not cooled or cannot be sufficiently cooled.
In addition, in the configuration in which the developer is deprived of heat via the developer regulating member 331, the developer and the developer regulating member 331 are in contact with each other for a very short time, and thus the developer cannot be sufficiently cooled.

  An object of the present invention is to sufficiently cool the developer.

The developing device according to the first aspect of the present invention is disposed to face an image carrier that carries a latent image based on an image formed on a print medium, and carries the developer so that the image carrier is used as the developer. A developing unit that develops the developer, an agitation conveyance unit that agitates and conveys the stored developer , and is interposed between the development unit and the agitation conveyance unit , and is provided above the agitation conveyance unit. and characterized by comprising a conveying guide part for guiding the conveyance from the stirring conveyance of the developer conveyed to the developing unit, and a developer cooling unit for cooling the developer through the conveying guide unit To do.

  Invention of Claim 2 is a developing device of Claim 1, Comprising: The said conveyance guide part has a conveyance guide member which slides and guides the said developer, The said developer cooling part is It has a conveyance guide member cooling part which cools the above-mentioned conveyance guide member.

According to a third aspect of the present invention, the image carrier is disposed opposite to an image carrier that carries a latent image based on an image formed on a print medium, and a developer is carried to develop the image carrier with the developer. A developing unit, an agitating and conveying unit that agitates and conveys the stored developer, and a developer that is interposed between the developing unit and the agitating and conveying unit and is conveyed from the agitating and conveying unit to the developing unit A conveyance guide portion having a conveyance guide member that guides the conveyance of the developer by sliding the developer, and a conveyance guide member cooling portion that cools the conveyance guide member, and the developer is cooled via the conveyance guide portion. And a developer cooling section.

According to a fourth aspect of the present invention, the image carrier is disposed opposite to an image carrier that carries a latent image based on an image formed on a print medium, and a developer is carried to develop the image carrier with the developer. A developing unit, a stirring transport unit that stirs and transports the stored developer, and a developer transported by the stirring transport unit interposed between the developing unit and the stirring transport unit. A conveyance guide unit having a supply roller that guides the conveyance of the developer by supplying the developer to the developing unit, and a supply roller cooling unit that cools the supply roller, and the developer is cooled via the conveyance guide unit. And a developer cooling section.
According to a fifth aspect of the present invention, in the developing device according to any one of the first to third aspects, the transport guide unit carries the developer transported by the agitation transport unit and performs the development. The developer cooling unit includes a supply roller cooling unit that cools the supply roller.
A sixth aspect of the present invention is the developing device according to any one of the first to fifth aspects, wherein the developer cooling section includes a liquid cooling mechanism that cools the transport guide section by liquid cooling. It is characterized by that.

The invention described in claim 7 is the developing device according to any one of claims 1 to 6, wherein the developing unit is a developing roller for carrying the developer on the outer peripheral surface of a magnetic, And a regulating member that adjusts the amount of the developer carried on the developing roller to a predetermined amount before the developer conveyed from the conveyance guide unit to the developing roller is conveyed to the image carrier. To do.

The invention according to claim 8 is the developing device according to any one of claims 1 to 7 , wherein the temperature detection unit detects the temperature of the developer, and the temperature detected by the temperature detection unit. And a control unit for controlling the operation of the developer cooling unit based on the above.
The invention according to claim 9 is disposed opposite to an image carrier that carries a latent image based on an image formed on a print medium, carries a developer, and develops the image carrier with the developer. A developing section;
An agitating and conveying unit for agitating and conveying the stored developer;
A conveyance guide unit that guides conveyance of a developer that is interposed between the developing unit and the stirring and conveying unit and is conveyed from the stirring and conveying unit to the developing unit;
A developer cooling section for cooling the developer via the transport guide section;
A temperature detector for detecting the temperature of the developer;
And a control unit that controls the operation of the developer cooling unit based on the temperature detected by the temperature detection unit.

An image forming apparatus according to a tenth aspect of the invention includes the developing device according to any one of the first to ninth aspects.

  According to the present invention, the developer can be sufficiently cooled.

1 is an explanatory diagram illustrating a configuration of an image forming apparatus according to a first embodiment. 2 is a functional block diagram of the image forming apparatus 1. FIG. 2 is a cross-sectional view illustrating a detailed configuration of the developing device 200. FIG. It is explanatory drawing which shows the structure of the cooling device. It is a perspective view of a conveyance guide plate and a conveyance guide plate support part. FIG. 6 is a perspective view illustrating an example of a conveyance guide plate to which toner is fused. An example of paper having white streaks is shown. It is sectional drawing which shows the fixing device by 2nd embodiment. FIG. 10 is a functional block diagram of an image forming apparatus according to a third embodiment. It is explanatory drawing which shows the structure of a temperature detection part and a cooling device. It is a flowchart which shows the flow of operation control of the cooling device by a control part. FIG. 10 is an explanatory diagram showing a configuration example of a conventional developing device 300.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration of an image forming apparatus 1 according to the first embodiment of the present invention.
As shown in FIG. 1, the image forming apparatus 1 reads an image from a document, forms a read image on a sheet P, and outputs it, page data including image data from an external device or the like, and each image data A print function for receiving a job including the image forming conditions, and forming and outputting an image on the paper P based on the received job. As shown in FIG. 1, the image forming apparatus 1 includes an image reading unit 20, a printing unit 40, and the like.

The image reading unit 20 includes an automatic document feeder 21 called an ADF (Auto Document Feeder) and a reading unit 22. The document d placed on the document tray 21a of the automatic document feeder 21 is conveyed to a contact glass which is a reading location, and an image on one or both sides of the document d is read by an optical system, and a CCD (Charge Coupled Device) 22a. As a result, the image of the document d is read. Here, the image means not only image data such as graphics and photographs but also text data such as characters and symbols.

  The image (analog image signal) read by the image reading unit 20 is output to the control unit 90 to be described later, subjected to various image processing such as A / D conversion in the control unit 90, and then to the printing unit 40. Is output.

  The print unit 40 performs an electrophotographic image forming process based on the input print data, and includes a paper feed unit 41, a conveyance unit 42, an image formation unit 43, a fixing unit 60, an unloading unit 45, an unloading unit 45, and an unloading unit 45. A standby unit 46 is provided.

  The paper feed unit 41 includes a plurality of paper feed trays 41a, a paper feed unit 41b, a manual feed tray 41c, and the like. The paper feed tray 41a stores standard paper, special paper, insertion paper, and other paper P identified for each paper feed tray 41a on the basis of the amount and size of the paper for each preset type. The paper P is transported one by one from the top toward the transport unit 42 by the paper feeding means 41b. The manual feed tray 41c is a paper feed tray on which various types of paper P can be stacked according to the user's needs, and transports the paper P stacked by the paper feed rollers one by one from the top to the transport unit 42. To do.

  The transport unit 42 transports the paper P transported from the paper feed tray 41a or the manual feed tray 41c to the secondary transfer belt 51 through a plurality of intermediate rollers, registration rollers 42a, and the like. The registration roller 42a functions as a first standby unit that temporarily waits for a sheet conveyed to the secondary transfer belt 51. The secondary transfer belt 51 receives the toner image on the intermediate transfer member (intermediate transfer belt 43b). Secondary transfer to paper.

  Further, the conveyance unit 42 conveys the sheet P on which the single-sided image formation processing has been performed to the double-side conveyance path by the conveyance path switching plate, and conveys the sheet P again to the secondary transfer belt 51 through the intermediate roller and the registration roller 42a. By the secondary transfer belt 51, a toner image primarily transferred to an intermediate transfer belt 43b described later is secondarily transferred onto the paper P.

  For example, when forming an image of four colors (yellow (Y), magenta (M), cyan (C), and black (K)), the image forming unit 43 is provided for each color that can be filled with toner of different colors. The image forming units 43Y, 43M, 43C, and 43K, an intermediate transfer belt 43b, and a cleaning unit 43d are provided.

  For example, the image forming unit 43Y primarily places a toner image on which an electrostatic latent image based on image data is developed on the intermediate transfer belt 43b, a charging device, an exposure device, and a developing device 200 arranged around the photosensitive drum 251. A primary transfer roller 43Ya that functions as a primary transfer unit for transfer and a cleaning device 254 are provided to form a yellow (Y) image.

  Specifically, the photosensitive drum 251 charged by the charging device 252 is irradiated with light according to yellow (Y) image data from the exposure device to form an electrostatic latent image. The developing device 200 develops the electrostatic latent image by attaching yellow (Y) toner to the surface of the photosensitive drum 251 on which the electrostatic latent image is formed. The photosensitive drum 251 to which the toner is attached by the developing device 200 is primarily transferred to the intermediate transfer belt 43b while being rotated at a constant speed to the transfer position where the primary transfer roller 43Ya is disposed. After the toner is primarily transferred to the intermediate transfer belt 43b, the cleaning device removes residual charges, residual toner, and the like on the surface of the photosensitive drum 251.

  The image forming units 43M, 43C, and 43K have the same configuration as the image forming unit 43Y, and form magenta (M), cyan (C), and black (K) images, respectively.

The intermediate transfer belt 43b is a semiconductive endless belt that is suspended and supported rotatably by a plurality of rollers, and is driven and moved with the rotation of a roller such as a drive roller.
The intermediate transfer belt 43b is pressure-bonded to the respective photosensitive drums 251 by the primary transfer rollers 43Ya, 43Ma, 43Ca, and 43Ka of the image forming units 43Y, 43M, 43C, and 43K. As a result, each toner developed on the surface of each photosensitive drum 251 is sequentially superposed with yellow, magenta, cyan, and black toners on the intermediate transfer belt 43b at the transfer positions by the primary transfer rollers 43Ya, 43Ma, 43Ca, and 43Ka. Are transferred to the sheet P at the transfer position by the secondary transfer roller 52.

  The intermediate transfer belt 43b secondarily transfers the toner image onto the paper P by the secondary transfer roller 52, and then separates the paper P from the curvature and electrostatically, and the residual toner is removed by the cleaning unit 43d.

  In the fixing unit 60, a rotary fixing member 61 having a heat source 61 a and a fixing belt 62 that presses against the rotary fixing member 61 to form a fixing nip heat-fix the toner image secondarily transferred to the paper P.

  The carry-out unit 45 has a plurality of paper discharge rollers, a carry-out port 45a, and a paper discharge surface switching path 45b. The paper P on which the toner image is fixed by the fixing unit 60 by the conveyance path switching plate is used as the paper discharge roller. A paper discharge surface switching unit that switches the paper surface of the paper that is nipped and carried out from the carry-out port 45a to the carry-out standby unit 46, or the paper P on which the toner image is fixed is held between the paper discharge rollers and discharged to the carry-out standby unit 46. After being transported to the paper discharge surface switching path 45b that functions as a transport port, it is transported from the transport outlet 45a to the transport standby unit 46.

  The unloading standby unit 46 is provided between the unloading unit 45 and the sheet discharge tray 47, and includes a plurality of sheet discharge rollers, a first unloading path 46a, and a second unloading path 46b. Then, the paper carried in from the carry-out port 45 a is conveyed to the first carry-out path 46 a or the second carry-out path 46 b and then discharged to the paper discharge tray 47.

  The first carry-out path 46a is a path for discharging the paper carried in from the carry-out port 45a to the paper discharge tray 47 on the same surface as the paper surface carried in from the carry-out port 45a. The second carry-out path 46b functions as a second standby unit that temporarily waits for the paper carried in from the carry-out port 45a, and is a path that discharges the paper to the paper discharge tray 47 at a predetermined timing. The first carry-out path 46a This is a path for discharging paper to the paper discharge tray 47 on the reverse side to the paper surface carried out to the paper discharge tray 47.

  A paper position detection unit 80 for recognizing the position of the paper P is provided on the upstream side of the secondary transfer belt 51 in the transport direction of the paper P. When the paper position detection unit 80 detects the passage of the paper P conveyed by the conveyance unit 42, the paper position detection unit 80 outputs a signal to that effect (hereinafter referred to as a detection signal). The detection signal is input to a control unit 90 (see FIG. 2) described later.

FIG. 2 shows a functional block diagram of the image forming apparatus 1.
The image forming apparatus 1 includes a control unit 90, a communication unit 110, an image memory 120, an operation display unit 130, and a cooling device 240.

The control unit 90 includes a CPU 91, a RAM 92, a ROM 93, etc., which are connected to each other by a bus 94. The control unit 90 controls the operation of the image forming apparatus 1 by so-called software processing in which software corresponding to the processing content is called from the ROM 93 or the like, loaded into the RAM 92, and executed.
The control unit 90 is connected to the image reading unit 20, the print unit 40, the paper position detection unit 80, the communication unit 110, the image memory 120, the operation display unit 130, and the cooling device 240 via the bus 150, and based on the input of each unit. Each part is controlled to control the operation of the image forming apparatus 1.

The communication unit 110 includes an interface (for example, a NIC (Network Interface Card) or the like) that can be connected to an external device (for example, a PC), and enables communication between the image forming apparatus 1 and the external device. For example, image data transmitted from a PC or the like is received by the image forming apparatus 1 via the communication unit 110 and stored in the image memory 120.

  The image memory 120 is a storage area for storing image data to be formed on the paper P by the image forming apparatus 1, and includes a storage device (for example, a volatile memory). Image data read from the image reading unit 20 and image data transmitted via the communication unit 110 are stored in the image memory 120. The control unit 90 forms an image on the paper P based on the image data stored in the image memory 120.

  The operation display unit 130 includes an LCD (Liquid Crystal Display), a touch panel, and the like, and can display various information related to the image forming apparatus 1 and perform various input operations by an operator.

  The cooling device 240 cools a conveyance guide unit 210 (described later) provided in the developing device 200. The cooling device 240 will be described later.

FIG. 3 is a sectional view showing the detailed configuration of the developing device 200.
The developing device 200 includes a developing roller 201, stirring and conveying members 205 and 206, a conveying guide unit 210, and a developer layer thickness regulating member 231.

  The developing roller 201 carries a developer and develops the photosensitive drum 251 with the developer. As shown in FIG. 3, the developing roller 201 is a cylindrical member, and a magnet 202 is provided in the cylinder. As shown in FIG. 3, the magnet 202 has a seven-pole magnet provided asymmetrically. Each of the seven-pole magnets is different in at least one of the strength or polarity of the magnetic force with respect to the adjacent pole.

  The developing roller 201 rotates a nonmagnetic sleeve that is an outer peripheral surface of the magnet 202. The magnet 202 is fixed at a predetermined angle. The developer includes a magnetic carrier and a toner that is a pigment. When the developer is conveyed to the outer peripheral surface of the developing roller 201, the carrier and toner are carried on the outer peripheral surface of the developing roller 201 by the magnetic force of the magnet 202 in the developing roller 201. When the developer passes through the vicinity of the photosensitive drum 251 due to the rotation of the developing roller 201, a part of the toner flies to the photosensitive drum 251 by the electric field formed between the photosensitive drum 251 and the developing roller 201, and the photosensitive drum 251 is exposed. It is carried on the body drum 251. In this way, a toner image corresponding to the electrostatic latent image and the electric field is formed. The developer that has passed through the vicinity of the photosensitive drum 251 is returned to the inside of the developing device 200, that is, the opposite side of the photosensitive drum 251 with the developing roller 201 interposed therebetween. The developer returned to the inside of the developing device 200 is peeled off from the developing roller 201 and falls into the casing 222 of the developing device 200.

  As shown in FIG. 3, in the image forming apparatus 1 of the first embodiment, the rotation direction of the developing roller 201 and the rotation direction of the photosensitive drum 251 are the same, and the outer peripheral surfaces of the image forming apparatus 1 are located at positions close to each other. However, the present invention is not limited to this, and the rotation direction of the developing roller 201 and the rotation direction of the photosensitive drum 251 may be reversed.

The developer layer thickness regulating member 231 is a plate-like member that adjusts the amount of developer carried on the developing roller 201 to a predetermined amount.
The outer peripheral surface of the developing roller 201 carrying the developer passes through the position where the developer layer thickness regulating member 231 is provided in the process of rotating around the photosensitive drum 251. At this time, the developer layer thickness regulating member 231 adjusts the amount of developer carried on the developing roller 201 to a predetermined amount. As a result, the amount of toner to be developed can be suitably maintained.

  The agitating and conveying members 205 and 206 agitate and convey the developer (not shown) stored in the casing 222 of the developing device 200. The agitating and conveying members 205 and 206 have blades (screws) that are spirally connected, and agitate the developer stored in the casing 222 by the rotation thereof. The agitating / conveying members 205 and 206 convey the developer to the supply roller 211 side of the conveyance guide unit 210 by the rotation thereof.

  The conveyance guide unit 210 is interposed between the developing roller 201 and the agitation conveyance members 205 and 206 to guide the developer conveyed from the agitation conveyance member 205 and guide the developer to the development roller 201. As shown in FIG. 3, the conveyance guide unit 210 of the first embodiment is provided above the agitation conveyance member 205. The conveyance guide unit 210 includes a supply roller 211, a conveyance guide plate 215, and a conveyance guide plate support unit 216.

  As shown in FIG. 3, the supply roller 211 is a cylindrical member, and a magnet 212 is provided in the cylinder. As shown in FIG. 3, the magnet 212 has a five-pole magnet provided asymmetrically. Each of the five-pole magnets is different in at least one of the strength or polarity of the magnetic force with respect to the adjacent poles.

  The supply roller 211 rotates a nonmagnetic sleeve that is a peripheral surface of the magnet 212. The magnet 212 is fixed at a predetermined angle. When the developer is conveyed to the outer peripheral surface of the supply roller 211, the carrier and toner are carried on the outer peripheral surface of the supply roller 211 by the magnetic force of the magnet 212 in the supply roller 211. When the developer passes near the conveyance guide plate 215 due to the rotation of the supply roller 211, the developer on the supply roller is scraped by the end of the conveyance guide plate and the developer carried on the supply roller 211 is conveyed to the conveyance guide. It is conveyed onto the plate 215.

The conveyance guide plate 215 is a plate-like member that is installed between the supply roller 211 and the developing roller 201 so as to be inclined downward from the supply roller 211 toward the developing roller 201. The transport guide plate 215 slides the developer transported by the supply roller 211 and passed on the transport guide plate 215 to the developing roller 201 by sliding with the inclination.
The developer guided by the conveyance guide plate 215 is accumulated by a predetermined amount in a space surrounded by the conveyance guide plate 215, the developing roller 201, the developer layer thickness regulating member 231, and the conveyance guide upper portion 221. It is carried out at any time by rotating and carrying.

  The conveyance guide plate support 216 is a member constructed so as to support the conveyance guide plate 215. The conveyance guide plate support 216 has a cylindrical shape having a cavity inside. A cooling material 217 is filled in the cavity of the conveyance guide plate support 216. The coolant 217 is a liquid coolant and flows through the cavity of the transport guide plate support 216 by the cooling device 240 to cool the transport guide plate support 216 and the transport guide plate 215. The conveyance guide plate 215 cooled by the coolant 217 cools the developer on the conveyance guide plate 215. In other words, the coolant 217 cools the developer on the transport guide plate 215 via the transport guide plate support 216 and the transport guide plate 215.

FIG. 4 shows the configuration of the cooling device 240.
As illustrated in FIGS. 3 and 4, the cooling device 240 includes a pump 241 and a cooling unit 242. The pump 241, the cooling unit 242 and the conveyance guide plate support unit 216 are connected by a pipe 243, and the coolant 217 is provided so as to circulate in the cavity of the pump 241, the cooling unit 242 and the conveyance guide plate support unit 216.

  The pump 241 causes the coolant 217 to flow and circulates in the cavities of the pump 241, the cooling unit 242, and the conveyance guide plate support unit 216.

  The cooling unit 242 cools the coolant 217. The cooling unit 242 is, for example, a radiator or the like, but may be any configuration that can cool the coolant 217.

The coolant 217 that has passed through the cavity of the conveyance guide plate support 216 removes heat from the conveyance guide plate support 216. As a result, the transport guide plate support 216 is cooled, and the transport guide plate 215 that contacts the transport guide plate support 216 and the developer that contacts the transport guide plate 215 are also cooled. The coolant 217 that has passed through the transport guide plate support 216 is cooled by the cooling unit 242 and flows again to the transport guide plate support 216.
Thus, the cooling device 240 cools the developer guided by the transport guide plate 215 by cooling the transport guide plate 215 and the transport guide plate support 216 by liquid cooling.

  The coolant 217 of the first embodiment is an antifreeze coolant such as ethylene glycol, but is not particularly limited to this and may be a coolant used for liquid cooling.

FIG. 5 is a perspective view of the conveyance guide plate 215 and the conveyance guide plate support 216. In FIG. 5, illustration of the coolant 217 in the conveyance guide plate support 216 is omitted.
As shown in FIG. 5, the width direction of the conveyance guide plate 215 and the conveyance guide plate support 216 in the first embodiment is the same in the direction orthogonal to the inclination direction of the conveyance guide plate 215. As a result, the developer flowing on the transport guide plate 215 and the transport guide plate 215 can be suitably cooled.

  In addition, although the cross-sectional shape of the conveyance guide plate support part 216 of 1st embodiment is trapezoid, the form will not be ask | required if it is a structure which can support and cool the conveyance guide plate 215.

Specific design items of the image forming apparatus 1 will be described below, but the configuration of the present invention is not particularly limited to this.
The diameter of the developing roller 201 is φ25 [mm]. The rotation ratio between the developing roller 201 and the photosensitive drum 251 is 1.8: 1. The rotation speed of the developing roller 201 is 550 [rpm]. The diameter of the supply roller 211 is φ16 [mm]. The rotation speed of the supply roller 211 is 240 [rpm]. The dimension of the conveyance guide plate 215 is 24 × 327 × 0.8 [unit mm]. The transport guide plate support 216 has dimensions of a base 15 [mm], a height 6 [mm] /10.5 [mm], and a thickness of a member covering the cavity is 2 [mm]. The gap between the developing roller 201 and the conveyance guide plate 215 is 0.50 ± 0.25 [mm]. The gap between the supply roller 211 and the conveyance guide plate 215 is 0.75 ± 0.25 [mm]. The gap between the conveyance guide plate 215 and the conveyance guide upper portion 221 is 4 ± 0.25 [mm]. A gap between the supply roller 211 and the conveyance guide upper part 221 is 5 ± 0.25 [mm]. The agitating / conveying members 205 and 206 have a diameter of φ30 [mm], a spiral number of one, a spiral lead of 39 [mm], a rotating shaft diameter of φ8 [mm] / 6 [mm], and a rotational speed of 510 [mm]. rpm] and the blade height is 11 [mm]. The average particle size of the carrier contained in the developer is 33 [μm], and the average particle size of the toner is 6.5 [μm]. The developer capacity of the developing device 200 is 1200 g.

  Although the conveyance guide plate 215 of the first embodiment is made of stainless steel and the conveyance guide plate support 216 is made of aluminum, it is not particularly limited to these materials. As the material of the conveyance guide plate 215 and the conveyance guide plate support 216, it is preferable to use a non-magnetic high heat conductive material, for example, an aluminum alloy, a copper alloy, a zinc alloy, etc. in addition to the aforementioned stainless steel and aluminum.

Next, the cooling effect by the cooling device 240 will be described. First, for comparison, a case where the cooling of the developer by the cooling device 240 is not performed will be described with reference to FIGS. 6 and 7.
FIG. 6 shows an example of the conveyance guide plate 218 in which the toner is fused. The conveyance guide plate support 219 that supports the conveyance guide plate 218 illustrated in FIG. 6 does not have a cavity for circulating the coolant 217. For this reason, the conveyance guide plate 215 and the conveyance guide plate support part 216 of the first embodiment are illustrated with different symbols. The illustrated conveyance guide plate 218 and conveyance guide plate support 219 are the same as the conveyance guide plate 215 and conveyance guide plate support 216 in terms of their installation positions and materials, except that they are not cooled by the cooling device 240 due to their structures. It is.

  Agitation of the developer by the agitation conveyance members 205 and 206 and conveyance of the developer by the conveyance and supply roller 211 cause friction between the developer and each part of the developing device 200 and friction between the developers. These frictions generate frictional heat. For this reason, each part of the developing device 200 and the developer are heated.

  For this reason, if image formation is continued without the developer being cooled by the cooling device 240, the developer may continue to be heated by frictional heat, and the toner may melt. For example, as shown in FIG. 6, the melted toner is fused on the developer conveyance path such as the conveyance guide plate 218.

FIG. 7 shows an example of the paper P on which the white stripe S is generated.
If the image formation is continued in the state where the toner fusing as shown in FIG. 6 (fusing toner G shown in FIG. 6) has occurred, white streaks S or the like are added to the image formed on the paper P as shown in FIG. Image formation defects may occur. This is due to the fact that the toner that has been fused prevents the flow of developer at and near the location where the toner has been fused, so that a sufficient amount of developer cannot be conveyed to the developing roller 201.

  Also, the fused toner shown in FIG. 6 may fall over and the lump of toner may become clogged between the developing roller 201 and the developer layer thickness regulating member 231. In such a case, the developer is excessively restricted from the developing roller 201 by the clogged toner lump, and the white stripe S as shown in FIG.

When image formation is performed under predetermined conditions with the same configuration as that of the image forming apparatus 1 except that the cooling device 240 is not provided, the developer on the conveyance guide plate 218 is compared with that before the start of image formation. About 15 degrees [° C]. At this time, on the conveyance guide plate 218, a phenomenon occurs in which the toner is fused and the melted toner block is clogged between the developing roller 201 and the developer layer thickness regulating member 231 as shown in FIG. Such white streaks S were generated in the image.
Here, the image formation under a predetermined condition means that the image formation is continuously performed for 4 hours in an environment where the temperature is 30 degrees [° C.] and the humidity is 80 percent [% RH] and the document coverage is 5 percent [%]. This is the case. The developer temperature is measured by a K thermocouple.

  On the other hand, when the image forming apparatus 1 of the first embodiment that cools the developer by the cooling device 240 performs image formation under the above-described predetermined conditions, the temperature rise of the developer on the conveyance guide plate 215 is increased. As a result, the temperature remained at about 5 ° C. compared to before the start of image formation, and neither toner fusing nor white stripes S occurred. As described above, the developing device 200 included in the image forming apparatus 1 according to the first embodiment can sufficiently cool the developer in the developing device 200, and causes poor image formation due to toner fusion and toner fusion. And good image formation can be performed.

As described above, according to the first embodiment, the cooling device 240 circulates the coolant 217 in the cavity of the conveyance guide plate support 216 and cools the developer via the conveyance guide plate support 216 and the conveyance guide plate 215. . As a result, it is possible to suppress poor image formation due to the toner contained in the developer being melted and fused by heat, and obtain an image of good quality.
Further, the developer guided by the conveyance guide plate 215 is deposited by a predetermined amount in a space surrounded by the conveyance guide plate 215, the developing roller 201, the developer layer thickness regulating member 231, and the conveyance guide upper portion 221. The developer in the space is carried on the developing roller 201 with a high probability. Since the developer accumulated in the space is cooled via the conveyance guide plate 215, the developer carried on the developing roller 201 can be reliably cooled. As described above, the developing device 200 of the image forming apparatus 1 has a configuration that can sufficiently cool the developer.

  Further, the cooling of the developer by the cooling device 240 is performed via the transport guide plate 215 of the transport guide unit 210 positioned in front of the developing roller 201 in the developer transport path. Since the conveyance guide plate 215 is in contact with the developer on the plate-like upper surface, the developer can be cooled through a wide surface portion.

  Further, the cooling device 240 is a liquid cooling type cooling device that cools the conveyance guide plate support 216 via the coolant 217. Since the cooling device 240 cools the coolant 217 by the cooling unit 242 and circulates it to the transport guide plate support unit 216, the coolant 217, which is a refrigerant that takes heat away from the transport guide plate support unit 216, is sufficiently cooled. The developer can be circulated to the transport guide plate support 216, and the developer can be cooled more reliably.

  Further, the developing roller 201 develops the developer on the photosensitive drum 251, and the developer layer thickness regulating member 231 is carried on the developing roller 201 before the developer carried on the developing roller 201 approaches the photosensitive drum 251. Since the amount of the developer is adjusted to a predetermined amount, the amount of the developer conveyed to the photosensitive drum 251 can be appropriately maintained. Even in such a configuration, the developer is sufficiently cooled by the cooling device 240, so that the toner is melted, fused, and a lump of the melted toner is formed between the developing roller 201 and the developer layer thickness regulating member 231. A good quality image can be obtained without being sandwiched between them.

  As described above, since the image forming apparatus 1 includes the developing device 200 that can sufficiently cool the developer, image formation defects due to melting and fusing of the toner are suppressed, and an image with good quality is obtained. be able to.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. About the structure similar to 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 8 shows a developing device 200B according to the second embodiment.
The developing device 200B of the second embodiment allows the coolant 217 to pass through a gap (sleeve) between the supply roller 211 and the magnet 212. The pipe 243 of the cooling device 240 is connected to the sleeve and is provided to seal the sleeve. The coolant 217 in the second embodiment circulates through the pump 241, the cooling unit 242, and the sleeve. In the developing device 200 </ b> B of the second embodiment, the coolant 217 is not passed through the cavity in the conveyance guide plate support 216. Except for the circulation location of the coolant 217, the configuration of the second embodiment is the same as that of the first embodiment.

  According to the second embodiment, the same effect as that of the first embodiment can be obtained. Further, since the developer is cooled when the developer is carried on the outer peripheral surface of the supply roller 211 of the conveyance guide unit 210, the developer conveyed to the developing roller 201 via the conveyance guide unit 210 is reliably cooled. can do.

  In the developing device 200B of the second embodiment, the coolant is not passed through the cavity in the transport guide plate support 216, but may be passed. The circulation path of the coolant 217 by one cooling device 240 may include both the cavity and the sleeve in the transport guide plate support 216, or each of the cavity and the sleeve in the transport guide plate support 216 may be individually provided. The cooling device 240 may be provided.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. About the structure similar to 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 9 shows a functional block diagram of an image forming apparatus 1C according to the third embodiment.
The image forming apparatus 1C according to the third embodiment includes a temperature detection unit 245 in addition to the configuration of the image forming apparatus 1 according to the first embodiment.

FIG. 10 shows configurations of the temperature detection unit 245 and the cooling device 240.
The temperature detection unit 245 is provided at a position where the temperature of the developer on the conveyance guide plate 215 can be detected, and detects the temperature of the developer.

  The control unit 90 of the third embodiment controls the operation of the cooling device 240 based on the developer temperature detected by the temperature detection unit 245. Specifically, when the temperature of the developer becomes equal to or higher than a predetermined temperature, the control unit 90 operates the pump 241 to cool the developer. On the other hand, when the temperature of the developer is lower than the predetermined temperature, the control unit 90 stops the pump 241 to stop the cooling of the developer.

  The predetermined temperature is set based on the melting temperature of the toner contained in the developer. For example, when the predetermined temperature is lower than the predetermined temperature, it is preferable to set the predetermined temperature so as not to cause image formation failure due to melting of the toner.

FIG. 11 is a flowchart showing the flow of operation control of the cooling device 240 by the control unit 90.
The controller 90 determines whether or not image formation by the image forming apparatus 1C is being performed (step S1). When image formation is not performed (step S1: NO), the control unit 90 ends the process.

  If image formation is being performed in step S1 (step S1: YES), the control unit 90 determines whether or not the temperature of the developer detected by the temperature detection unit 245 is equal to or higher than a predetermined temperature (step S1). S2). When the temperature of the developer is equal to or higher than the predetermined temperature (step S2: YES), the control unit 90 operates the pump 241 (step S3) to cool the developer.

  After step S3, the control unit 90 determines whether or not the temperature of the developer detected by the temperature detection unit 245 has fallen below a predetermined temperature (step S4). When the temperature of the developer is lower than the predetermined temperature (step S4: YES), the control unit 90 stops the pump 241 (step S5) and stops the cooling of the developer. On the other hand, if the developer temperature does not fall below the predetermined temperature in step S4 (step S4: NO), the process waits until the developer temperature falls below the predetermined temperature.

  After step S5 or when the developer temperature is not equal to or higher than the predetermined temperature in step S2 (step S2: NO), the process returns to step S1.

  According to the third embodiment, in addition to the effects of the first embodiment, the cooling device 240 is operated to cool the developer when the temperature of the developer detected by the temperature detection unit 245 is equal to or higher than a predetermined temperature. Therefore, the developer can be cooled according to the necessity of cooling the developer.

  The embodiment of the present invention should be considered that the embodiment disclosed this time is illustrative and not restrictive in all respects. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, the cooling device is not limited to liquid cooling, and may be any configuration that can cool the developer via the conveyance guide unit 210. For example, the method using a heat pipe is mentioned. By bringing the heat pipe into contact with the conveyance guide plate support 216 and the conveyance guide plate 215 so that the heat of the heat pipe is dissipated outside the developing device 200, the same effect as in the above-described embodiment can be obtained. . In addition, air cooling or the like may be used.

  In the third embodiment, the control unit 90 of the image forming apparatus 1 controls the operation of the cooling device 240 based on the detection result of the temperature detection unit 245, but the cooling device 240 is based on the detection result of the temperature detection unit 245. A control unit 90 for controlling the operation may be provided individually.

  The developer is not limited to one containing both toner and carrier. For example, the present invention can be applied even when only toner is used.

90 control unit 200 developing device 201 developing roller 205 stirring and conveying member 210 conveying guide unit 211 supply roller 215 conveying guide plate 216 conveying guide plate support unit 217 coolant 231 developer layer thickness regulating member 240 cooling device 241 pump 242 cooling unit 243 pipe 251 Photosensitive drum

Claims (10)

A developing unit that is disposed opposite to an image carrier that carries a latent image based on an image formed on a print medium, carries a developer, and develops the image carrier with the developer;
An agitating and conveying unit for agitating and conveying the stored developer;
A conveyance guide unit interposed between the developing unit and the agitation conveyance unit , and provided above the agitation conveyance unit, for guiding conveyance of the developer conveyed from the agitation conveyance unit to the development unit; ,
A developer cooling section for cooling the developer via the transport guide section;
A developing device comprising: The transport guide portion includes a transport guide member that slides and guides the developer,
The developing device according to claim 1, wherein the developer cooling unit includes a conveyance guide member cooling unit that cools the conveyance guide member. A developing unit that is disposed opposite to an image carrier that carries a latent image based on an image formed on a print medium, carries a developer, and develops the image carrier with the developer;
An agitating and conveying unit for agitating and conveying the stored developer;
A conveyance guide unit having a conveyance guide member interposed between the developing unit and the agitation conveyance unit to guide conveyance of the developer conveyed from the agitation conveyance unit to the development unit by sliding the developer; ,
A developer cooling unit that has a conveyance guide member cooling unit that cools the conveyance guide member, and that cools the developer via the conveyance guide unit;
A developing device comprising: A developing unit that is disposed opposite to an image carrier that carries a latent image based on an image formed on a print medium, carries a developer, and develops the image carrier with the developer;
An agitating and conveying unit for agitating and conveying the stored developer;
A conveyance guide having a supply roller that guides the conveyance of the developer by supporting the developer conveyed by the agitation conveyance unit interposed between the developing unit and the agitation conveyance unit and supplying the developer to the development unit. And
A developer roller cooling unit that cools the developer via the conveyance guide unit, and a supply roller cooling unit that cools the supply roller;
A developing device comprising: The transport guide unit includes a supply roller that carries the developer transported by the stirring transport unit and supplies the developer to the developing unit.
The developing device according to claim 1, wherein the developer cooling unit includes a supply roller cooling unit that cools the supply roller. The developing device according to claim 1, wherein the developer cooling unit includes a liquid cooling mechanism that cools the transport guide unit by liquid cooling. The developing unit is a developing roller that carries the developer on its outer peripheral surface by magnetism,
And a regulating member that adjusts the amount of the developer carried on the developing roller to a predetermined amount before the developer conveyed from the conveyance guide unit to the developing roller is conveyed to the image carrier. The developing device according to any one of claims 1 to 6. A temperature detector for detecting the temperature of the developer;
The developing device according to claim 1, further comprising: a control unit that controls an operation of the developer cooling unit based on a temperature detected by the temperature detection unit. A developing unit that is disposed opposite to an image carrier that carries a latent image based on an image formed on a print medium, carries a developer, and develops the image carrier with the developer;
An agitating and conveying unit for agitating and conveying the stored developer;
A conveyance guide unit that guides conveyance of a developer that is interposed between the developing unit and the stirring and conveying unit and is conveyed from the stirring and conveying unit to the developing unit;
A developer cooling section for cooling the developer via the transport guide section;
A temperature detector for detecting the temperature of the developer;
A control unit that controls the operation of the developer cooling unit based on the temperature detected by the temperature detection unit;
A developing device comprising: An image forming apparatus comprising the developing device according to claim 1.

Images