JP2010156816A - Developing device, image forming apparatus, and method for controlling developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of image quality regardless of the amount of toner consumption, when successively carrying out printing. <P>SOLUTION: A developing device 1 includes: a developing tank 2 for storing developer; a Peltier device 9 for heating and cooling the inside of the developing tank 2; and a control section 17 that controls the Peltier device 9. When the amount of toner supplied to the developing tank 2 per unit time is smaller than a predetermined amount P1 and the temperature in the inside of the developing tank 2 is higher than a predetermined temperature T1 (Yes in S3), the control section 17 cools the inside of the developing tank 2 by the use of the Peltier device 9 (S4). When the amount of toner supplied to the developing tank 2 per unit time is larger than a predetermined amount P2 and the temperature of the inside of the developing tank 2 is lower than a predetermined temperature T2 (Yes in S6), the control section 17 heats the inside of the developing tank 2 by the use of the Peltier device 9 (S7). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device, an image forming apparatus, and a developing device control method using a two-component developer.

  An image forming apparatus using an electrophotographic system includes a charging device, an exposure device, a developing device, a transfer device, a cleaning device, a charge eliminating device, and a fixing device. In the case of forming an image, the surface of a rotating photosensitive member (photosensitive drum) is uniformly charged by a charging device, and then the surface of the photosensitive member is irradiated with laser light to form an electrostatic latent image. Subsequently, the electrostatic latent image is developed by a developing device to form a toner image on the surface of the photoreceptor. The toner image is transferred onto a sheet (paper, transfer material) by a transfer device, and then the toner image is fixed on the sheet by heating the sheet with a fixing device. Further, the transfer residual toner remaining on the surface of the photoreceptor is removed by a cleaning device and collected in a predetermined collection unit. Further, the static eliminator removes residual charges from the surface of the photoreceptor after cleaning.

  In the development processing for developing the electrostatic latent image on the photosensitive member, a one-component developer composed only of toner or a two-component developer including toner and carrier is generally used. The one-component developer does not use a carrier and thus has an advantage of simplifying the developing device, but has a drawback that the charge amount of the toner is difficult to stabilize. The two-component developer requires a stirring mechanism for uniformly mixing the toner and the carrier. However, the two-component developer is often used in a high-speed image forming apparatus and a color image forming apparatus because of excellent charge amount stability. Yes.

  A developing device using a two-component developer generally has a developing tank, a developing roller, a stirring member, a regulating member, a sink plate, and the like. The developing tank rotatably supports the developing roller and the stirring member and accommodates the developer therein. The developing roller attracts the developer in the developing tank to the surface, carries and rotates, and supplies toner to the electrostatic latent image on the surface of the photoreceptor to form a toner image. The agitating member uniformly agitates the developer in the developing tank and conveys the developer toward the developing roller. The regulating member (doctor blade) is a plate-like member that regulates the layer thickness of the developer layer on the surface of the developing roller.

  In recent years, as binder resins for toners used in two-component developers, those that soften at low temperatures and those that are added with a low-melting wax are used in order to cope with higher printing speeds and energy savings. It has become to. Therefore, when the temperature of the toner rises due to friction between the doctor blade and the developer during continuous printing, there arises a problem that the toner tends to aggregate.

In order to solve the above temperature increase problem, Patent Document 1 discloses that an air passage including an intake port and an exhaust port is formed in a developer container (development tank) that contains a developer, and cooling air is supplied to the air passage. In addition, a developing container and a developing device that cools the developer contained in the developing container are disclosed.
JP 2008-129562 A (released on June 5, 2008)

  In addition, a free external additive (external additive attached to the surface of the toner particles while maintaining the fluid state) is added to the toner replenished in the developing tank in order to improve the fluidity of the toner. Here, when the toner consumption per unit time of the developing device is large during continuous printing (for example, when continuously printing images with high coverage), the amount of free external additives is excessive in the developing tank. In addition, when the toner consumption of the developing device per unit time is small during continuous printing (for example, when continuously printing images with low coverage), the amount of free external additive is too small in the developing tank. Hereinafter, the reason why the amount of the free external additive is excessive or excessive will be described in detail.

  When the developer temperature is high, the above-mentioned free external additive is easily embedded or fixed in the toner as the toner is softened. On the other hand, when the developer temperature is low, the toner is not easily softened and is embedded in the toner. Or it becomes difficult to adhere. The toner after being replenished to the developing tank usually increases in temperature slightly due to repeated friction with the doctor blade by circulating in the developing tank. A fixed external additive is produced, and the amount of free external additive is reduced. Therefore, in anticipation of this decrease, a new toner is added with an amount of free external additive slightly larger than the appropriate amount.

  Here, when the amount of toner consumption per unit time is large during continuous printing, the amount of new toner replenished per unit time becomes large and the amount of free external additives becomes excessive. Further, when the amount of toner consumed per unit time is large, the amount of new toner immediately after replenishment in the developing tank is temporarily large, and the ratio of the toner sufficiently receiving friction with the doctor blade is high. The temperature of the developer in the developing tank is relatively low. As a result, the free external additive is hardly embedded in the toner, and the free external additive that has become excessive as described above is difficult to decrease. Therefore, if the toner consumption per unit time is large during continuous printing, the amount of free external additives in the developing device becomes excessive.

  On the other hand, if the amount of toner consumed per unit time is small during continuous printing, toner that has sufficiently passed through the developer tank and has received sufficient friction with the doctor blade will be stored in the developer tank. Therefore, the developer temperature in the developing tank is excessively high, the external additive is buried in the toner excessively, and the amount of the free external additive is excessively small. . In this case, since the amount of toner replenished to the developing tank per unit time is small, the amount of newly added free external additive is small. Therefore, when the toner consumption per unit time becomes small during continuous printing, the free external additive is too small in the developing device.

  For the above reasons, if the toner consumption per unit time becomes large during continuous printing, the amount of free external additives in the developing tank becomes excessive, and if the toner consumption per unit time becomes small during continuous printing, The free external additive becomes insufficient.

  When the amount of free external additive is excessive in the developing tank, the free external additive easily adheres to the photoconductive drum, causing photoconductor filming, and image unevenness occurs due to the photoconductor filming. However, the problem of image quality degradation occurs. Further, when the amount of the free external additive is too small in the developing tank, the fluidity of the developer is extremely lowered and the image density is lowered. In this case as well, there is a problem of image quality deterioration.

  To solve these problems, an external additive having a small particle size (7 to 16 nm) that is easily embedded or fixed on the surface of the binder resin forming the toner particles, and a large particle size (50 to 100 nm) that is difficult to be embedded and fixed on the surface of the binder resin. A method is conceivable in which the amount of the free external additive is prevented from abruptly changing by adding the external additive to the toner at an appropriate blending ratio. However, it has been found that this method is not sufficient to solve the above problems.

  The present invention has been made in view of the above problems, and even when the amount of toner consumption per unit time becomes large during continuous printing or when the amount of toner consumption per unit time becomes small during continuous printing. Another object of the present invention is to provide a developing device, an image forming apparatus, and a control method of the developing device in which the occurrence of image quality deterioration is suppressed.

  The developing device of the present invention that solves the above-described problem is a container that contains a developer containing toner and a carrier and that is supplied with toner from a replenishing device, and the toner in the developing bath is supplied to the photoreceptor. In a developing device including a developing roller, a temperature detecting unit that detects a developing bath temperature that is an internal temperature of the developing bath, a replenishing amount detecting unit that detects a toner replenishing amount per unit time, and A heating unit for heating the inside of the developing tank, a cooling unit for cooling the inside of the developing tank, the toner replenishment amount is less than a first predetermined amount, and the developing tank temperature is higher than the first predetermined temperature. In this case, the inside of the developing tank is cooled by the cooling unit, and the toner replenishment amount is larger than the second predetermined amount set as an amount larger than the first predetermined amount, and is lower than the first predetermined temperature. Set as temperature If second predetermined temperature the developing tank temperature is lower than that of, characterized in that it comprises a temperature control unit for heating the interior of the developer tank to the heating unit.

  In the present invention, when the toner replenishment amount per unit time is less than the first predetermined amount and the developing tank temperature is higher than the first predetermined temperature, the inside of the developing tank is cooled. Therefore, when the amount of toner consumed during continuous printing is small (when the amount of toner replenished per unit time is small), the developer tank temperature is adjusted so that the developer temperature in the developer tank is lower than a predetermined level. Will do. This temperature adjustment makes it difficult for the external additive to be buried in the toner, thereby suppressing the amount of the free external additive from being excessive, and suppressing the decrease in developer fluidity caused by the excessive free external additive. Is done.

  On the other hand, when the toner replenishment amount per unit time is larger than the second predetermined amount and the developing tank temperature is lower than the second predetermined temperature, the inside of the developing tank is heated. Therefore, when the amount of toner consumed during continuous printing is large (when the amount of toner replenished per unit time is large), the temperature of the developing tank is adjusted so that the developer temperature in the developing tank becomes higher than a predetermined level. Will do. By adjusting the temperature, the external additive is easily embedded in the toner, the excessive free external additive is suppressed, and the photoreceptor filming caused by the excessive free external additive can be suppressed.

  Therefore, according to the present invention, even if the toner consumption per unit time becomes large during continuous printing, or even when the toner consumption per unit time becomes small during continuous printing, the image quality deterioration can be suppressed. Play.

  Further, in the developing device of the present invention, when a regulating member for regulating the amount of the developer adhering to the developing roller is installed inside the developing tank, the developer and the inside of the developing tank are caused by friction between the regulating member and the developer. The temperature rises.

  Therefore, in the developing device of the present invention that solves the above problem, the temperature detection unit includes a temperature sensor that detects the temperature of the regulating member, and detects the temperature sensed by the temperature sensor as the developing tank temperature. It is preferable that it is such.

  In this invention, since the temperature of the regulating member is detected as the temperature of the developing tank, the temperature rise caused by the friction can be detected quickly, and the developer is cooled after the temperature rise occurs. You can shorten the period until it starts. Therefore, it is possible to suppress the occurrence of a situation in which the cooling of the developer is started after the temperature of the developer inside the developing tank has excessively increased.

  Furthermore, in the developing device of the present invention that solves the above problem, it is preferable that the temperature sensor is attached to the restricting member, and the restricting member is made of metal.

  According to the present invention, the heat of friction between the developer and the regulating member can be quickly transmitted to the temperature sensor by the metal having high thermal conductivity, and the temperature detecting unit can quickly change the temperature inside the developing tank. Can be detected.

  In the developing device of the present invention that solves the above-described problem, the temperature sensor is attached to a surface of the restricting member that is downstream of the gap between the restricting member and the developing roller in the rotation direction of the developing roller. It is preferable that

  In this invention, the temperature sensor is disposed at a location where the developer in the developing tank is difficult to reach, and the amount of the developer fused to the temperature sensor can be suppressed. It is possible to suppress the deterioration of the temperature detection accuracy caused. Therefore, reliable temperature detection can be performed over a long period of time.

  In addition, the developing device of the present invention that solves the above-mentioned problems preferably includes a Peltier element that functions as the heating unit and also functions as the cooling unit.

  In this invention, the said heating part and the said cooling part are implement | achieved by the single apparatus (Peltier element). Therefore, the developing device can be made smaller than the case where both the heating device that functions as the heating unit but does not function as the cooling unit and the cooling device that functions as the cooling unit but does not function as the heating unit are provided. it can.

  Furthermore, in the developing device of the present invention that solves the above-mentioned problems, it is preferable that the Peltier element is included in the developing tank as a part of the wall of the developing tank.

  In this invention, since the developer inside the developing tank is in direct contact with the Peltier element, the developer can be efficiently heated and cooled. When the Peltier element is a part of the bottom wall of the developing tank, a larger amount of developer can be brought into contact with the Peltier element.

  Further, the developing device of the present invention that solves the above-mentioned problems preferably has a duct facing the Peltier element on the outside of the developing tank.

  In this invention, it is possible to ventilate the cool air outside the developing tank that is generated when the developer inside the developing tank is heated by the Peltier element, and the outside of the developing tank that is generated when the developer inside the developing tank is cooled by the Peltier element. Since the warm air can be ventilated, temperature control inside the developing tank by the Peltier element can be realized efficiently.

  The present invention may also be an image forming apparatus having the developing device described above. The present invention also includes a developing tank that contains a developer containing toner and a carrier and that is supplied with toner from a replenishing device, and a developing roller that supplies the toner in the developing tank to the photoreceptor. In the apparatus control method, a temperature detecting step for detecting a developing bath temperature, which is a temperature inside the developing bath, a replenishing amount detecting step for detecting a toner replenishing amount to the developing bath per unit time, and the developing bath A heating step for heating the inside of the toner and a cooling step for cooling the inside of the developing tank, wherein the toner replenishing amount is less than a first predetermined amount and the developing tank temperature is higher than the first predetermined temperature. The cooling step is executed, and the second toner amount supplied is larger than the second predetermined amount set as an amount larger than the first predetermined amount and is set as a temperature lower than the first predetermined temperature. From a predetermined temperature Wherein when developing tank temperature is low, it may be configured to perform the heating step.

  As described above, when the toner replenishment amount is smaller than the first predetermined amount and the developing tank temperature is higher than the first predetermined temperature, the developing device of the present invention has an internal portion of the developing tank in the cooling unit. The toner supply amount is larger than a second predetermined amount set as an amount larger than the first predetermined amount, and is higher than a second predetermined temperature set as a temperature lower than the first predetermined temperature. When the developing tank temperature is low, the heating unit includes a temperature control unit that heats the inside of the developing tank. Therefore, even if the toner consumption per unit time becomes large during continuous printing or the toner consumption per unit time becomes small during continuous printing, there is an effect that image quality deterioration can be suppressed.

  An image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a front view schematically showing the overall configuration of the image forming apparatus 100 of the present embodiment. The image forming apparatus 100 is an electrophotographic digital copying machine capable of executing both a copying mode and a printing mode. In the copy mode, the image forming apparatus 100 copies a document image according to the document image information read by the scanner unit 29. In the print mode, the image forming apparatus 100 prints an image according to image information received from an external device such as a personal computer connected to the image forming apparatus 100 via a network.

  The image forming apparatus 100 includes a photosensitive drum 20, a charger 21, an exposure unit 22, a developing device 1, a transfer unit 23, a cleaning unit 24, a fixing unit 25, a paper feed tray 28, and a scanner unit. 29 and a paper discharge tray 30.

  The photosensitive drum 20 is a roller-like member that is supported by a driving unit (not shown) so as to be rotatable about an axis, and that has a photosensitive film on the surface of which an electrostatic latent image and thus a toner image is formed.

  The charger 21 is connected to a power source (not shown), and is a charging means for uniformly charging the surface of the photosensitive drum 20 to a predetermined polarity and potential in the vicinity of the photosensitive drum 20. The charger 21 is a charger-type charger as shown in FIG. 2, a brush-type charger, a roller-type charger, a saw-tooth type charger, an ion generator, a contact-type charger such as a magnetic brush, or the like. Also good.

  The exposure unit 22 (optical scanning device) is arranged on the upper side of the photosensitive drum 20. In the present specification, the upward direction means a direction opposite to the vertical direction (the direction of gravity).

  The exposure unit 22 inputs read image information from the scanner unit 29 or image information from an external device, and irradiates the charged surface of the photosensitive drum 20 with signal light corresponding to the image information. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 20. The exposure unit 22 is a laser scanning unit (LSU) that combines a semiconductor laser (light source), a polygon mirror, an fθ lens, a reflection mirror, and the like. However, the exposure unit 22 is not limited to the laser scanning unit, and may be an exposure device using an LED array as a light source or an exposure device using electroluminescence (EL) as a light source. In the image forming apparatus 100, the exposure unit 22 is disposed on the upper side of the photosensitive drum 20.

  The transfer unit 23 includes a transfer roller 23 a that is rotatably supported by a support member (not shown) and rotatably provided by a drive unit (not shown), and is disposed so as to be in pressure contact with the photosensitive drum 20. As the transfer roller 23a, for example, a roller-shaped member including a metal core having a diameter of 8 to 10 mm and a conductive elastic layer formed on the surface of the metal core is used. As the metal forming the metal core, stainless steel, aluminum, or the like can be used. As the conductive elastic layer, a rubber material in which a conductive material such as carbon black is blended with a rubber material such as ethylene-propylene rubber (EPDM), foamed EPDM, or foamed urethane can be used.

  In synchronism with the conveyance of the toner image by the rotation of the photosensitive drum 20 to the pressure contact portion (transfer nip portion) between the photosensitive drum 20 and the transfer roller 23a, the pickup roller, the conveyance roller and the resist Sheets (recording media) are supplied one by one through the rollers. Then, when the sheet passes through the transfer nip portion, the toner image on the surface of the photosensitive drum 20 is transferred to the sheet. A power source (not shown) is connected to the metal core of the transfer roller 23a, and when transferring the toner image to the sheet, a voltage having a polarity opposite to the charging polarity of the toner constituting the toner image is applied to the transfer roller 23a. Thus, the toner image on the surface of the photosensitive drum 20 is smoothly transferred to the sheet.

  The cleaning unit 24 includes a cleaning blade (not shown) and a toner storage tank (not shown). The cleaning blade is a strip-shaped plate member that is provided so that the axial direction of the photosensitive drum 20 is the long side direction and one end in the short direction is in contact with the surface of the photosensitive drum 20. The cleaning blade removes toner, paper dust, and the like remaining on the surface of the photosensitive drum 20 from the surface of the photosensitive drum 20 after the toner image is transferred to the sheet. The toner storage tank is a container-like member having an internal space, and temporarily stores the toner removed by the cleaning blade. The surface of the photosensitive drum 20 after the toner image is transferred is cleaned by the cleaning unit 24.

  The fixing unit 25 includes a fixing roller 26 and a pressure roller 27. The fixing roller 26 is a roller-like member that is rotatably supported by a support member (not shown) and is rotatable around an axis line by a drive unit (not shown). The fixing roller 26 has a heating member (not shown) inside, and heats and melts the toner constituting the unfixed toner image carried on the sheet conveyed from the transfer nip portion to fix it on the sheet. As the fixing roller 26, for example, a roller-shaped member including a cored bar and an elastic layer is used. The core metal is formed of a metal such as iron, stainless steel, or aluminum. The elastic layer is formed of an elastic material such as silicone rubber or fluorine rubber, for example. The heating member is a halogen lamp or an infrared lamp that generates heat upon application of a voltage from a power source (not shown).

  The pressure roller 27 is a roller-like member that is rotatably supported by a support member (not shown) and is in pressure contact with the fixing roller 26. The pressure roller 27 rotates following the rotation of the fixing roller 26. A pressure contact portion between the fixing roller 26 and the pressure roller 27 is a fixing nip portion. The pressure roller 27 promotes the fixing of the toner image to the sheet by pressing the sheet against the toner in the molten state when the fixing roller 26 heats and fixes the toner image to the sheet. A roller-like member having the same configuration as that of the fixing roller 26 can be used for the pressure roller 27. A heating member may also be provided inside the pressure roller 27. As the heating member, the same heating member as that in the fixing roller 26 can be used.

  In the fixing unit 25, the sheet on which the toner image is transferred passes through the fixing nip portion, and the toner constituting the toner image is pressed against the sheet, whereby the toner is fixed on the sheet. The sheet on which the toner is fixed is discharged and stacked on a discharge tray 30 provided on the side surface of the image forming apparatus 100 by a conveying unit (not shown).

  The paper feed tray 28 is a tray for storing sheets such as plain paper (paper), coated paper, color copy paper, and OHP film. A plurality of paper feed trays 28 are provided, and sheets of different sizes are stored in each paper feed tray 28. The sheet size includes A3, A4, B5, and B4. Further, sheets of the same size may be accommodated in a plurality of paper feed trays 28.

  The scanner unit 29 is provided with a document setting tray (not shown), an automatic document feeder (RADF), and the like, and a document reading device (not shown). The automatic document feeder conveys the documents placed on the document set tray one by one to the document placing table of the document reading device. The document reading device includes a document placing table and a document scanning device. The document placing table is a glass plate-like member for placing a document for reading image information. The document scanning device includes a light source, a reflecting member, an optical lens, a line sensor, and the like. The line sensor is configured by photoelectric conversion elements (for example, CCD: Charge Coupled Device) arranged in a row, and reads image information of a document placed on a document placement table for each line.

  In the document scanning device, a light source (not shown) and the first reflecting mirror reciprocate at a constant speed V in parallel along the lower surface of the document mounting table, and light is applied to the image forming surface of the document placed on the document mounting table. And a reflected light image is obtained by light irradiation. The first reflecting mirror reflects the reflected light image toward the second reflecting mirror, the second reflecting mirror reflects the reflected light image toward the third reflecting mirror, and the third reflecting mirror reflects the reflected light. Reflect the image towards the optical lens. The second and third reflection mirrors reciprocate at a speed of V / 2 following the reciprocation of the first reflection mirror. The optical lens forms a reflected light image reflected by the third reflecting mirror on the line sensor. The line sensor photoelectrically converts the reflected light image formed by the optical lens into an electrical signal, and outputs the electrical signal (image information) to an image processing unit in a control circuit board (not shown). Image information from an external device is also input to the image processing unit, and the image processing unit converts image information input from the document reading apparatus or the external device into an electrical signal and outputs the electrical signal to the exposure unit 22.

  Next, the developing device 1 included in the image forming apparatus 100 will be described. FIG. 3 is a diagram schematically showing the internal configuration of the developing device 1. As shown in FIG. 1, the developing device 1 includes a developing tank 2, and inside the developing tank 2, a developing roller 3, a first stirring member 4, a second stirring member 5, a conveying member 6, and a regulation member. A blade 7 (regulating member) and a sink plate 8 are provided.

  The developing tank 2 is a cylindrical container member that is formed so that the length in a direction parallel to the axial direction of the photosensitive drum 20 is long, and a portion facing the photosensitive drum 20 is opened. Inside the developing tank 2, a developing roller 3, a first stirring member 4, a second stirring member 5, and a conveying member 6 are arranged in order from the side close to the photosensitive drum 20. The developing roller 3, the first stirring member 4, the second stirring member 5, and the conveying member 6 are rotatably supported in the developing tank 2.

  Further, the developing tank 2 supports the regulating blade 7 and the sink plate 8 directly or via other members, and accommodates the developer therein.

  Here, in this embodiment, the developer means a two-component developer including toner and a carrier that is magnetic powder. In the developing device 1 of the present embodiment, an external additive having a small particle diameter (7 to 16 nm) that is easily embedded or fixed on the surface of the binder resin forming the toner particles, and a large particle that is difficult to be embedded and fixed on the surface of the binder resin. A two-component developer in which an external additive having a diameter (50 to 100 nm) is blended with a toner at an appropriate blending ratio is used.

  In the developing device 1, a toner replenishing port 2 b is formed on the wall of the developing tank 2 on the upper side of the conveying member 6. Further, as shown in FIGS. 2 and 3, a toner cartridge 51 is provided on the upper side of the developing tank 2. The toner cartridge 51 is detachably attached to the image forming apparatus 100 and accommodates toner therein.

  In the toner cartridge 51, an opening 51b is formed on the bottom surface which is the wall surface on the developing tank 2 side. Further, the toner cartridge 51 is disposed on the developing tank 2 so that the opening 51b and the toner supply port 2b overlap. Then, the inside of the toner cartridge 51 and the inside of the developing tank 2 communicate with each other through the toner supply port 2b and the opening 51b.

  Further, as shown in FIG. 3, a toner replenishing roller 51a is provided in the toner cartridge 51 and above the opening 51b. The toner supply roller 51a is rotatably supported by the toner cartridge 51 and is driven to rotate by a driving unit (not shown). The toner in the toner cartridge 51 is supplied to the developing tank 2 through the toner supply port 2b by the rotational drive of the toner supply roller 51a.

  A toner concentration detection sensor 12 having a sensor surface exposed to the inside of the developing tank 2 is provided on the bottom surface of the developing tank 2 below the second stirring member 5. In the present specification, the downward direction means the same direction as the vertical direction (the direction of gravity).

  The toner concentration detection sensor 12 is a sensor for detecting the toner concentration of the developer stored in the developing tank 2. Further, the toner density detection sensor 12 is connected to a control unit 17 (see FIG. 5) described later. In general, a transmitted light detection sensor, a reflected light detection sensor, a magnetic permeability detection sensor, or the like can be used as the toner concentration detection sensor 12. Among these, a magnetic permeability detection sensor is preferable.

  The controller 17 controls the rotational driving of the toner supply roller 51 a in the toner cartridge 51 in accordance with the toner density detection result by the toner density detection sensor 12. That is, when the control unit 17 determines that the density detected by the toner density detection sensor 12 is lower than the predetermined density, the control unit 17 sends a control signal to a toner supply roller driving motor that drives the toner supply roller 51a to rotate, thereby supplying the toner supply roller 51a. Is rotated to supply toner to the developing tank 2.

  The developing roller 3 includes a multipolar magnetic body 13 and a sleeve 14. The sleeve 14 is a cylindrical member that is rotatably supported in the developing tank 2 and is rotationally driven around an axis by a driving unit (not shown). The multipolar magnetic body 13 is formed by disposing a plurality of fan-shaped bar magnets whose cross-sectional shape extends radially from the multipolar magnetic body shaft portion 13a so as to be spaced apart from each other in the circumferential direction. Has been placed.

  Further, each bar is arranged such that the magnetic poles N1, S1, N2, S2, and S3 of each bar magnet are arranged in this order along the direction opposite to the rotation direction of the developing roller 3 (sleeve 14) (G direction in FIG. 3). A magnet is arranged. The base portion of each bar magnet is fixed to the multipolar magnetic material shaft portion 13 a, and the multipolar magnetic material shaft portion 13 a is supported by the tank wall of the developing tank 2.

  The developing roller 3 is disposed so that a gap is generated between the developing roller 3 and the photosensitive drum 20. In the gap (development nip portion) between the photosensitive drum 20 and the developing roller 3, toner is supplied from the developer layer (not shown) on the surface of the developing roller 3 to the electrostatic latent image on the surface of the photosensitive drum 20. The In the developing nip portion, a developing bias voltage is applied to the developing roller 3 from a power source (not shown) connected to the developing roller 3, and the electrostatic charge on the surface of the photosensitive drum 20 from the developer layer on the surface of the developing roller 3. The transfer of toner to the latent image proceeds smoothly.

  Each of the first stirring member 4 and the second stirring member 5 is a roller-like member provided so as to be rotatable around an axis by a driving means (not shown). In the present embodiment, the first stirring member 4 rotates counterclockwise (the same direction as the G direction), and the second stirring member 5 rotates clockwise (the direction opposite to the G direction). The first stirring member 4 is provided at a position facing the photosensitive drum 20 via the developing roller 3 and on the lower side of the developing roller 3. The second agitating member 5 is provided at a position facing the developing roller 3 through the first agitating member 4 and on the lower side with respect to the developing roller 3. The first agitating member 4 and the second agitating member 5 agitate the developer stored in the developing tank 2 to give a uniform charge to the toner, and pump up the charged developer to Send to the surroundings.

  The conveying member 6 is a roller-like member provided so as to be rotationally driven by a driving unit (not shown). The conveying member 6 is provided on the lower side of the toner supply port 2b so as to face the first stirring member 4 with the second stirring member 5 interposed therebetween. The conveying member 6 conveys the toner replenished into the developing tank 2 through the toner replenishing port 2 b around the second stirring member 5.

  The regulating blade 7 (doctor blade) is a plate-like member provided inside the developing tank 2 and provided on an extension line in the radial direction of the developing roller 3. The regulating blade 7 is supported by the developing tank 2 at one end side in the short direction on the upper side of the developing roller 3, and the other end in the short side faces the surface of the developing roller 3 through a gap. It is attached.

  Further, the regulating blade 7 of the present embodiment is formed of a nonmagnetic metal plate having elasticity such as stainless steel and aluminum.

  The regulating blade 7 adjusts the amount of developer transported by the developing roller 3 by removing excess developer from the developer layer carried on the surface of the developing roller 3 and regulating the thickness of the developer layer to be constant. To do. Further, the regulation blade 7 imparts electric charge to the developer that is insufficiently charged in the developer layer by rubbing with the developer layer, and sufficiently charges the developer contained in the developer layer.

  The flow plate 8 is a rectangular plate-shaped member having a direction parallel to the axial direction of the developing roller 3 as a long side direction, and is disposed inside the developing tank 2. The flow plate 8 is located on the upstream side of the regulating blade 7 in the rotation direction of the developing roller 3, and is provided on the upper side of the first stirring member 4 and the second stirring member 5.

  The flow plate 8 is arranged so that one end in the short side direction faces the surface of the developing roller 3 with a gap and the other end faces in a direction away from the developing roller 3. In the present embodiment, the upper surface of the flow plate 8 is inclined so that the end portion on the developing roller 3 side is higher than the end portion on the opposite side to the developing roller 3 side.

  According to the developing device 1, the developer accommodated in the developing tank 2 is conveyed to the developing roller 3 side by the rotation of the first stirring member 4 and the second stirring member 5, where the developer is conveyed by the magnetic poles of the multipolar magnetic body 13. It is lifted and supplied to the surface of the developing roller 3 (sleeve 14). The developing roller 3 carries a developer layer on its surface and rotates. After the developer blade layer thickness is regulated by the regulating blade 7 and the developer is charged, the developing roller 3 is fixed on the photosensitive drum 20 at the development nip. The toner is supplied to the electrostatic latent image and developed.

  After the development is completed, the developing roller 3 further rotates and receives the developer again. On the other hand, the developer removed from the surface of the developing roller 3 by the regulating blade 7 temporarily stays in the space above the developing roller 3, and then flows in the direction away from the developing roller 3 on the upper surface of the flow plate 8. 2 Drops onto the stirring member 5 and returns between the second stirring member 5 and the conveying member 6. The developer returned between the second stirring member 5 and the conveying member 6 is mixed therewith with other developer and newly supplied toner, and then developed by the first stirring member 4 and the second stirring member 5. It is conveyed again toward the roller 3. That is, by providing the flow plate 8, the developer circulates inside the developing tank 2, and in this circulation, the developer flows smoothly, and the occurrence of uneven charging of the toner, toner blocking, and the like is prevented. The conveying member 6 conveys the toner supplied to the inside of the developing tank 2 around the second stirring member 5 according to the detection result by the toner concentration detection sensor 12.

  Furthermore, the developing device 1 of the present embodiment includes a temperature sensor 10, a Peltier element 9, and a duct 11, as shown in FIG. Further, as shown in FIG. 5, the developing device 1 includes a control unit 17 that controls each hardware included in the developing device 1, a rotation amount detecting device 44, a power supply circuit 41, drive motors 42 and 43, a blower fan 15, An exhaust fan 16 is provided. FIG. 5 is a block diagram showing a connection relationship of hardware included in the developing device 1.

  The temperature sensor 10 is a thermistor that senses the temperature of the regulating blade 7. Hereinafter, the temperature sensor 10 will be described in detail. The temperature sensor 10 is attached to the regulating blade 7 inside the developing tank 2. Further, as shown in FIG. 3, the regulating blade 7 is located on the upstream surface 7 a in the G direction with respect to the gap between the developing roller 3 and the regulating blade 7, and on the opposite side of the surface 7 a and the developing roller 3. And a back surface 7b on the downstream side in the G direction with respect to the gap between the control blade 7 and the regulating blade 7. The temperature sensor 10 is attached to the back surface 7 b of the regulating blade 7 and senses the temperature of the regulating blade 7 disposed inside the developing tank 2.

  Here, the regulating blade 7 is a metal having high thermal conductivity. Therefore, the temperature of the regulating blade 7 rises rapidly due to friction between the regulating blade 7 and the developer. That is, by monitoring the output of the temperature sensor 10, a rapid change in the developer temperature due to friction between the regulating blade 7 and the developer that occurs during continuous printing or the like can be quickly detected.

  As shown in FIG. 3, the Peltier element 9 is a plate-like member attached to the developing tank 2 as a part of the bottom surface of the developing tank 2. In the present embodiment, as shown in FIG. 3, the inner surface of the developing tank 2 in the Peltier element 9 is a front surface 9a, and the outer surface of the developing tank 2 in the Peltier element 9 is a rear surface 9b.

  The Peltier element 9 is a thermoelectric element, and is a device that raises the temperature of the developer by heating the inside of the developing tank 2 and lowers the temperature of the developer by cooling the inside of the developing tank 2. As shown in FIG. 5, the Peltier element 9 is connected to a power supply circuit 41 through electrical wiring, and is driven by a current supplied from the power supply circuit 41.

  When a current is supplied from the power supply circuit 41 to the Peltier element 9, one of the front surface 9a and the back surface 9b of the Peltier element 9 absorbs heat and the other surface generates heat. Further, when the direction of the current supplied to the Peltier element is reversed, the surface that absorbs heat and the surface that generates heat are interchanged.

  That is, when the direction of the current supplied to the Peltier element 9 when the front surface 9a of the Peltier element 9 generates heat and the back surface 9b absorbs heat is set to a predetermined direction, a current in a direction opposite to the predetermined direction is applied to the Peltier element. 9, the front surface 9a of the Peltier element 9 absorbs heat and the back surface 9b generates heat. Further, when the surface 9a of the Peltier element 9 (the surface on the inner side of the developing tank 2) is heated, the developer in the developing tank 2 is heated and the temperature of the developer rises, and the surface 9a of the Peltier element 9 is absorbed. Then, the developer in the developing tank 2 is cooled, and the temperature of the developer is lowered. Therefore, by supplying the current in the predetermined direction from the power supply circuit 41 to the Peltier element 9, the developer in the developing tank 2 is heated to raise the temperature of the developer, and the current in the direction opposite to the predetermined direction. Is supplied to the Peltier element 9 from the power supply circuit 41, so that the developer in the developing tank 2 can be cooled and the temperature of the developer can be lowered. In addition, as the Peltier element 9, what is generally marketed can be used, for example, a thermo module 9500/018 / 018MP manufactured by Ferrotec Corporation can be used.

  As shown in FIGS. 3 and 4, the duct 11 is installed at a position facing the back surface 9 b of the Peltier element 9 below the bottom surface of the developing tank 2. 4 is a cross-sectional view of the developing device 1 of FIG. 3 taken along the line AA ′.

  As shown in FIG. 4, when the direction parallel to the axis of the developing roller 3 and extending from one end side to the other end side of the shaft is the T direction, the duct 11 is directed in the T direction inside thereof. Designed to allow wind (W in FIG. 4) to flow. Specifically, in the duct 11, a discharge port 11b for discharging wind from the inside of the duct 11 to the outside is formed on the T direction side, and the inside of the duct 11 from the outside is formed on the opposite side to the T direction side. A blower port 11a is formed to send wind into the fan. The air discharged from the discharge port 11b is discharged to the outside of the image forming apparatus 100 by a wind guide (not shown) so as not to accumulate in the image forming apparatus 100.

  As shown in FIG. 4, the blower port 11 a is provided with a blower fan 15 that sends air into the duct 11 from the outside, and the exhaust port 11 b is an exhaust fan 16 that discharges wind from the inside of the duct 11 to the outside. Is provided. Thereby, the ventilation efficiency inside the duct 11 can be improved rather than the structure without the ventilation fan 15 and the exhaust fan 16. FIG. As shown in FIG. 5, the blower fan 15 is driven by a drive motor 42, and the exhaust fan 16 is driven by a drive motor 43.

  Next, the reason why the duct 11 is provided at a position facing the back surface 9b of the Peltier element 9 will be described.

  When the current in the predetermined direction is supplied to the Peltier element 9, the surface 9a generates heat and the back surface 9b absorbs heat when the current in the predetermined direction is supplied to the Peltier element 9 (the developing tank). This is because heat transfer occurs from the outside (2) to the area facing the surface 9a (inside the developing tank 2). Therefore, by continuing to generate heat on the front surface 9a of the Peltier element 9, the region facing the back surface 9b is cooled. However, if the region facing the back surface 9b is cooled too much, the efficiency of the heat transfer decreases. The heat generation efficiency of the surface 9a is reduced. In this regard, when the duct 11 is provided in the region facing the back surface 9b of the Peltier element 9, it is possible to ventilate the cold air in the region facing the back surface 9b. A decrease in heat generation efficiency can be suppressed.

  Further, when a current in the direction opposite to the predetermined direction is supplied to the Peltier element 9, the heat absorption of the front surface 9a and the heat generation of the back surface 9b occur when the current in the direction opposite to the predetermined direction is supplied to the Peltier element 9. This is because heat transfer occurs from the area facing the front surface 9a (inside the developing tank 2) to the area facing the back surface 9b (outside the developing tank 2). Therefore, by continuing to absorb heat on the front surface 9a of the Peltier element 9, the region facing the back surface 9b is warmed. However, if the region facing the back surface 9b is excessively warmed, the region facing the front surface 9a is changed from the back surface 9b. The efficiency of heat transfer to the region facing the surface decreases, and the endothermic efficiency of the surface 9a decreases. In this regard, when the duct 11 is provided in the region facing the back surface 9b of the Peltier element 9, the warm air in the region facing the back surface 9b can be ventilated, so the region facing the back surface 9b from the region facing the front surface 9a It is possible to suppress a decrease in the efficiency of heat transfer to the heat and to suppress a decrease in the endothermic efficiency.

  Further, as shown in FIG. 5, the developing device 1 is provided with a rotation amount detection device 44. The rotation amount detection device 44 is a sensor that detects the rotation amount of the toner supply roller 51a based on the output of a speed sensor that detects the rotation speed of the toner supply roller 51a. The rotation amount detection device 44 detects the rotation speed based on the output of a speed sensor that detects the rotation speed of the toner supply roller 51a, but drives a motor (not shown) that rotates the toner supply roller 51a. The number of revolutions may be detected based on a driving pulse (signal) used when performing.

  Next, the control unit 17 in FIG. 5 will be described. The control unit 17 includes a CPU (central processing unit) that executes instructions of a control program for realizing control of each hardware of the developing device 1, a ROM (read only memory) that stores the control program, and the program is expanded. The computer includes a random access memory (RAM) that is a work area for various data processing. The ROM also stores various setting values, table data, and the like. In addition, output results and the like from various sensors are written in the RAM, and the CPU performs various determination processes based on the output results and the various setting values. The control unit 17 according to the present embodiment is a computer used for controlling the developing device 1, but may be a control integrated circuit board. In addition, although the control unit 17 of the present embodiment is exclusively used for controlling the developing device 1, a computer or a control circuit that controls the entire image forming apparatus 100 may be used as the control unit 17.

  As shown in FIG. 5, the control unit 17 is connected to the temperature sensor 10, the rotation amount detection device 44, the power supply circuit 41, the drive motor 42, and the drive motor 43. That is, the control unit 17 controls the operations of the blower fan 15 and the exhaust fan 16 by inputting control signals to the drive motor 42 and the drive motor 43. In addition, the control unit 17 controls the operation of the Peltier element 9 by inputting a control signal to the power supply circuit 41.

  And the control part 17 contains the temperature measurement part 17a, the replenishment amount measurement part 17b, and the temperature control part 17c.

  The temperature measuring unit 17 a is a block that measures the developing tank internal temperature (developing tank temperature) that is the temperature inside the developing tank 2 based on the temperature sensed by the temperature sensor 10. More specifically, the temperature measuring unit 17a measures the temperature sensed by the temperature sensor 10 (the temperature of the regulating blade 7) as the developing tank internal temperature.

  The supply amount measuring unit 17b measures the toner supply amount per unit time (the toner amount supplied from the toner cartridge 51 to the developing tank 2) based on the rotation amount detected by the rotation amount detection device 44. ing. That is, the toner supply amount per rotation of the toner supply roller 51a is fixed, and the toner supply amount and the rotation number of the toner supply roller 51a are in a proportional relationship. Therefore, the toner per unit time is based on the rotation number. The replenishment amount can be measured.

  The temperature control unit 17c determines whether heating or cooling of the inside of the developing tank 2 is necessary based on the measurement result of the temperature measurement unit 17a and the measurement result of the replenishment amount measurement unit 17b, and if necessary, the Peltier element 9 Is driven to heat or cool the inside of the developing tank 2 to control the temperature of the developer inside the developing tank 2.

  The control unit 17 including the temperature measurement unit 17a, the replenishment amount measurement unit 17b, and the temperature control unit 17c performs the processing illustrated in FIG. 1 every time a unit time elapses during the image forming operation by the image forming apparatus 100. It is supposed to run. In this embodiment, the unit time is 2 minutes, but the unit time is not limited to 2 minutes.

  Below, the processing content of the control part 17 is demonstrated using FIG. FIG. 1 is a flowchart showing the flow of processing executed by the control unit 17.

  First, the temperature measuring unit 17a detects the internal temperature of the developing tank based on the output from the temperature sensor 10 (S1). Next, the supply amount measuring unit 17b detects the toner supply amount per unit time based on the output of the rotation amount detection device 44 (S2). More specifically, the replenishment amount measuring unit 17b obtains an accumulated value of the number of rotations of the toner replenishing roller 51a from the time point 2 minutes (unit time) before the time point S2 to the time point S2. The toner replenishment amount per unit time is measured based on the calculated value. That is, in the present embodiment, the toner replenishment amount per unit time corresponds to the toner replenishment amount from the time point 2 minutes (unit time) back to the time point S2 from the time point S2.

After S2, the temperature control unit 17c determines whether or not both of the following conditions 1 and 2 are satisfied (S3).
Condition 1: The amount of toner replenished per unit time detected in S2 is smaller than the predetermined amount P1.
Condition 2: The developing tank internal temperature detected in S1 is higher than the predetermined temperature T1.

  In S3, when it is determined that at least one of condition 1 and condition 2 is not satisfied (No in S3), temperature control unit 17c shifts the process to S6.

  On the other hand, when it is determined that both condition 1 and condition 2 are satisfied (Yes in S3), the controller 17 drives the Peltier element 9 so that the developer in the developing tank 2 is cooled. (S4). That is, in this case, the control unit 17 controls the direction of the current supplied from the power supply circuit 41 to the Peltier element 9 so that the surface 9a of the Peltier element 9 absorbs heat.

  In the present embodiment, the predetermined amount P1 is set to 1 g, and the predetermined temperature T1 is set to 60 ° C. Here, the value 1g of the predetermined amount P1 corresponds to a toner consumption amount when an image having a coverage of 2% is printed on 100 sheets of A4 size paper by the image forming apparatus 100 of the present embodiment. Further, the value of 60 ° C. of the predetermined temperature T1 corresponds to the glass transition point of the toner contained in the developer of the present embodiment (that is, the toner easily aggregates when it exceeds 60 ° C.). The optimum values of the predetermined amount P1 and the predetermined temperature T1 vary according to the characteristics of the image forming apparatus and the developer. The predetermined amount P1 is not limited to 1 g, and the predetermined temperature T1 is also set to 60 ° C. It is not limited.

  Further, the temperature controller 17c drives the blower fan 15 and the exhaust fan 16 together with the drive of the Peltier element 9 to ventilate the inside of the duct 11 (S5). Then, the temperature control unit 17c repeats S1 to S5 until either one of the above conditions 1 and 2 is not satisfied, and processing is performed when at least one of the conditions 1 and 2 is not satisfied. Is shifted to S6 (No in S3).

In S6, the temperature control unit 17c determines whether or not both of the following conditions 3 and 4 are satisfied.
Condition 3: The toner replenishment amount per unit time detected in S2 is larger than the predetermined amount P2.
Condition 4: The developing tank internal temperature detected in S1 is lower than the predetermined temperature T2.

  In S6, if temperature controller 17c determines that at least one of condition 3 and condition 4 is not satisfied (No in S6), the process proceeds to S9.

  If it is determined that both condition 3 and condition 4 are satisfied (Yes in S6), the temperature controller 17c drives the Peltier element 9 so that the developer in the developing tank 2 is heated (S7). ). That is, in this case, the control unit 17 controls the direction of the current supplied from the power supply circuit 41 to the Peltier element 9 so that the surface 9a of the Peltier element 9 generates heat.

  In the present embodiment, the predetermined amount P2 is set to 5 g, and the predetermined temperature T2 is set to 10 ° C. Here, the value 5 g of the predetermined amount P2 corresponds to a toner consumption amount when an image having a coverage of 10% is printed on 100 sheets of A4 size paper by the image forming apparatus 100 of the present embodiment. Further, the value of 10 ° C. of the predetermined temperature T2 corresponds to a necessary minimum temperature at which the external additive having a large particle diameter can be properly attached to the toner (if the temperature is lower than the necessary minimum temperature, The toner becomes too hard and it becomes difficult for the external additive having a large particle size to adhere to the toner).

  The optimum values of the predetermined amount P2 and the predetermined temperature T2 vary depending on the characteristics of the image forming apparatus and the developer. Therefore, the values of the predetermined amount P2 and the predetermined temperature T2 can be appropriately changed on condition that the predetermined amount P2 is larger than the predetermined amount P1 and the predetermined temperature T2 is lower than the predetermined temperature T1. The predetermined amount P2 is not limited to 5 g, and the predetermined temperature T2 is not limited to 10 ° C.

  Further, the temperature controller 17c drives the blower fan 15 and the exhaust fan 16 together with the drive of the Peltier element 9 to ventilate the inside of the duct 11 (S8). Thereafter, the temperature control unit 17c repeats S1 to S8 until either one of the condition 3 and the condition 4 is not satisfied. When the controller 17 does not satisfy any one of the condition 3 and the condition 4, the control unit 17 shifts the process to S9 (No in S6).

  In S <b> 9, the temperature control unit 17 c sends a control signal to the power supply circuit 41 and stops driving the Peltier element 9. That is, the temperature control unit 17 c stops supplying current from the power supply circuit 41 to the Peltier element 9. Thereby, the heat generation or heat absorption of the surface 9a of the Peltier element 9 is completed. Further, after S9, the temperature control unit 17c stops the blower fan 15 and the exhaust fan 16 (S10), and ends the process. The processes of S1 to S10 described above are performed every time a predetermined time elapses during the image forming operation.

  As described above, the process in FIG. 1 is performed during the execution of the image forming process. Therefore, even when the process of FIG. 1 is being executed, the control unit 17 ends the process of FIG. 1 at the end of the image forming process. That is, even when the control unit 17 is driving the Peltier element 9, the blower fan 15, and the exhaust fan 16, when the image forming process is finished, the operation of the Peltier element 9, the blower fan 15, and the exhaust fan 16 is performed. To stop.

  As described above, the developing device 1 according to the present embodiment is one in which toner is supplied from the toner cartridge 51 (replenishing device), and the developing tank 2 that stores the developer, and the toner in the developing tank 2 is charged with the photosensitive drum. The developing roller 3 is supplied to 20 (photoreceptor), and a regulating blade 7 (regulating member) that regulates the amount of developer adhering to the developing roller 3 is provided.

  Further, the developing device 1 of the present embodiment includes a cooling unit that cools the inside of the developing tank 2, a heating unit that heats the inside of the developing tank 2, and the temperature of the regulating blade 7 as the developing tank internal temperature (developing tank temperature). And a replenishment amount detection unit for detecting a toner replenishment amount to the developing tank 2 per unit time. The Peltier element 9 corresponds to the heating unit and the cooling unit, the temperature sensor 10 and the temperature measurement unit 17a correspond to the temperature detection unit, and the rotation amount detection device 44 and the supply amount measurement unit 17b correspond to the supply amount detection unit. It corresponds to.

  Furthermore, the developing device 1 of the present embodiment has a temperature control unit 17c. The temperature control unit 17c is configured to perform Peltier when the toner replenishment amount per unit time is smaller than a predetermined amount P1 (first predetermined amount) and the developing tank internal temperature is higher than a predetermined temperature T1 (first predetermined temperature). The element 9 is allowed to cool the inside of the developing tank 2. Further, the temperature controller 17c has a predetermined amount set to a temperature that is greater than the predetermined amount P2 (second predetermined amount) set as an amount larger than the predetermined amount P1 and that is lower than the predetermined temperature T1. When the temperature of the developing tank is lower than the temperature T2 (second predetermined temperature), the inside of the developing tank 2 is heated by the Peltier element 9.

  Therefore, according to the developing device 1 of the present embodiment, when the toner consumption amount is small during continuous printing (when the toner replenishment amount per unit time is small), the temperature of the developer in the developing tank 2 is predetermined. The temperature of the developing tank 2 is adjusted so as to be lower than the degree. This temperature adjustment makes it difficult for the external additive to be buried in the toner, thereby suppressing the amount of the free external additive from being excessive, and suppressing the decrease in developer fluidity caused by the excessive free external additive. Is done.

  Further, according to the developing device 1 of the present embodiment, when the amount of toner consumption is large during continuous printing (when the amount of toner replenished per unit time is large), the temperature of the developer in the developing tank 2 matches a predetermined degree. The temperature of the developing tank 2 is adjusted so as to be higher than that. By adjusting the temperature, the external additive is easily embedded in the toner, the excessive free external additive is suppressed, and the photoreceptor filming caused by the excessive free external additive can be suppressed.

  Therefore, according to the developing device 1 of the present embodiment, even if the toner consumption per unit time becomes large during continuous printing, or the toner consumption per unit time becomes small during continuous printing, the image quality deteriorates. There is an effect that can be suppressed.

  In the present embodiment, the temperature detection unit including the temperature measurement unit 17a and the temperature sensor 10 detects the temperature of the regulating blade 7 as the developing tank internal temperature (S1). Therefore, since the temperature rise of the developing tank 2 caused by the friction between the regulating blade 7 and the developer can be detected quickly, the period from when this temperature rise occurs until the cooling of the developer is started can be shortened. Therefore, it is possible to suppress the occurrence of a situation in which the cooling of the developer is started after the temperature of the developer inside the developing tank 2 has excessively increased.

  However, the developing tank internal temperature detected in S <b> 1 may be any temperature inside the developing tank 2, and is not necessarily limited to the temperature of the regulating blade 7. For example, a temperature sensor may be provided on the inner wall of the developing tank 2, and the temperature sensed by this temperature sensor may be the developing tank internal temperature detected in S1.

  In the present embodiment, the temperature sensor 10 is attached to the regulation blade 7, but the regulation blade 7 is preferably a non-magnetic metal plate of 1 mm or less, specifically stainless steel. This is because metal with high thermal conductivity can quickly transmit the frictional heat between the developer and the regulating blade 7 to the temperature sensor 10, and the temperature measuring unit 17 a can detect the temperature change inside the developing tank 2 more quickly. Because it will be possible. However, the regulation blade 7 is not necessarily made of metal, and may be a synthetic resin or the like.

  Further, among the surfaces of the regulating blade 7, the temperature sensor 10 is attached to a surface (back surface 7 b) on the downstream side in the rotation direction of the developing roller 3 with respect to the gap between the regulating blade 7 and the developing roller 3. As a result, the temperature sensor 10 is disposed at a location where the developer in the developing tank 2 is difficult to reach, and the amount of developer fused to the temperature sensor 10 can be suppressed, and the temperature caused by this fusion. Deterioration of detection accuracy can be suppressed. Therefore, reliable temperature detection can be performed over a long period of time.

  In the present embodiment, the Peltier element 9 functions as a cooling unit that cools the inside of the developing tank 2 and also functions as a heating unit that heats the inside of the developing tank 2. Therefore, it is possible to reduce the size of the developing device as compared with a configuration including both a heating device dedicated to heating and a cooling device dedicated to cooling.

  In the developing device 1 of the present embodiment, the Peltier element 9 is provided in the developing tank 2 as a part of the wall of the developing tank 2. Therefore, since the developer inside the developing tank 2 is in direct contact with the Peltier element 9, the developer can be efficiently heated and cooled. In the case where the Peltier element 9 is a part of the bottom wall of the developing tank 2 as in this embodiment, rather than the configuration in which the Peltier element is provided in the developing tank 2 as a part of the side wall of the developing tank, The amount of developer that contacts the Peltier element can be increased, and more efficient heating or cooling can be performed.

  Further, the developing device 1 of the present embodiment has a duct 11 facing the Peltier element 9 on the outside of the developing tank 2. Therefore, it is possible to ventilate the cool air outside the developing tank 2 that is generated when the developer inside the developing tank 2 is heated by the Peltier element 9, and the development that occurs when the developer inside the developing tank 2 is cooled by the Peltier element 9 Since the warm air outside the tank 2 can be ventilated, the temperature control inside the developing tank 2 by the Peltier element 9 can be efficiently realized. Furthermore, according to the present embodiment, since the outside of the developing tank 2 is ventilated by the duct 11, the developer in the developing nip portion is hardly affected by the wind generated by the ventilation, and the developer from the developing device 1 is not affected. Scattering can be suppressed, and scattering toner can be prevented from adhering to a portion other than the developing device 1 of the image forming apparatus 100.

  As described above, the developing device and the image forming apparatus including the developing device according to the embodiment of the present invention have been described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. It can be changed. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention is suitable for electrophotographic printers, copiers, multifunction machines, and facsimiles.

6 is a flowchart showing a flow of processing of a control unit included in the developing device according to the embodiment of the present disclosure. 1 is a diagram schematically illustrating an internal configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram schematically illustrating an internal configuration of a developing device according to an embodiment of the present invention. It is a figure which shows typically the cross section at the time of cut | disconnecting the image development apparatus shown by FIG. 3 by AA 'line. FIG. 3 is a block diagram showing a connection relationship of hardware included in a developing device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing device 2 Developing tank 3 Developing roller 7 Regulator blade (regulator member)
9 Peltier element (heating part, cooling part)
10 Temperature sensor (temperature detector)
11 Duct 17 Control unit 17a Temperature measurement unit (temperature detection unit)
17b Supply amount measurement unit (Supply amount detection unit)
17c Temperature controller (temperature controller)
20 Photosensitive drum (photosensitive member)
44 Rotation amount detector (Supply amount detector)
51 Toner cartridge (replenisher)
51a Toner supply roller 100 Image forming apparatus

Claims (9)

In a developing device that contains a developer containing toner and a carrier and is replenished with toner from a replenishing device, and a developing roller that supplies the toner in the developing bath to a photoreceptor,
A temperature detecting unit for detecting a developing tank temperature which is a temperature inside the developing tank;
A replenishment amount detection unit for detecting a replenishment amount of toner to the developing tank per unit time;
A heating unit for heating the inside of the developing tank;
A cooling unit for cooling the inside of the developing tank;
When the toner replenishment amount is less than the first predetermined amount and the developing tank temperature is higher than the first predetermined temperature, the cooling unit cools the inside of the developing tank and the amount is larger than the first predetermined amount. When the toner replenishment amount is larger than the second predetermined amount set as, and the developing tank temperature is lower than the second predetermined temperature set as a temperature lower than the first predetermined temperature, And a temperature control unit for heating the inside of the developing tank. A regulating member for regulating the amount of developer adhering to the developing roller is provided inside the developing tank,
The temperature detection unit includes a temperature sensor that senses the temperature of the regulating member, and detects the temperature sensed by the temperature sensor as the developing tank temperature. The developing device described.   The developing device according to claim 2, wherein the temperature sensor is attached to the restriction member, and the restriction member is made of metal.   4. The temperature sensor according to claim 3, wherein the temperature sensor is attached to a surface of the regulating member that is downstream of the gap between the regulating member and the developing roller in the rotation direction of the developing roller. Development device.   5. The developing device according to claim 1, further comprising a Peltier element that functions as the heating unit and also functions as the cooling unit. 6.   The developing device according to claim 5, wherein the Peltier element is included in the developing tank as a part of a wall of the developing tank.   The developing device according to claim 6, further comprising a duct facing the Peltier element on an outer side of the developing tank.   An image forming apparatus comprising the developing device according to claim 1. In a control method for a developing device that contains a developer containing toner and a carrier and is supplied with toner from a replenishing device, and a developing roller that supplies toner in the developing bath to a photoconductor.
A temperature detecting step for detecting a developing bath temperature which is a temperature inside the developing bath; a replenishing amount detecting step for detecting a toner replenishing amount per unit time; and heating for heating the inside of the developing bath. And a cooling step for cooling the inside of the developing tank. When the toner replenishment amount is smaller than a first predetermined amount and the developing tank temperature is higher than a first predetermined temperature, the cooling step is executed. ,
The developer tank temperature is higher than a second predetermined temperature set as a temperature lower than the first predetermined temperature and more than the second predetermined amount set as an amount larger than the first predetermined amount. When the temperature is low, the heating step is performed.

Images