JP2012226234A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of determining whether a transmission mechanism therein is abnormal.SOLUTION: When an image formation unit 5 forms an image on a paper sheet 3, a rotational period TP2 of an agitator 29 is detected after a switching operation of a transmission mechanism 100 is controlled so as to rotate the agitator 29 at a normal speed, and a rotational period TP1 of the agitator 29 is detected after the switching operation of the transmission mechanism 100 is controlled so as to rotate the agitator 29 at a slow speed. When it is determined that the TP2 coincides with the TP1, the transmission mechanism 100 is determined to be abnormal.

Description

  The present invention relates to an image forming apparatus.

  Conventionally, there has been proposed a technique for switching the rotational speed of an agitator in an image forming apparatus. For example, the image forming apparatus described in Patent Document 1 is provided with a gear transmission mechanism so as to transmit the drive from the main motor to the agitator, and the image forming apparatus is provided with a speed change mechanism including a gear, a clutch, or the like. A technique is described in which the agitator is rotationally driven at a high speed during formation, and the agitator is rotationally driven at a low speed when the remaining amount of developer is detected.

JP 2001-350339 A

  However, the image forming apparatus described in Patent Document 1 has a problem that it cannot be dealt with when the abnormality of the transmission mechanism cannot be determined and the rotation speed of the agitator cannot be switched due to the abnormality of the transmission mechanism.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of determining an abnormality of a transmission mechanism.

  In order to achieve this object, an image forming apparatus according to claim 1 is provided in an image forming unit that forms an image on a sheet, a storage unit that stores a developer, and the storage unit, and is rotated and driven. A stirring member that supplies the developer to the image forming unit and that stirs the developer; and a remaining amount detection sensor that detects the remaining amount of the developer; A detecting unit that detects a rotation period of the stirring member, a transmission mechanism that switches a rotation speed of the stirring member, a control unit that controls a switching operation of the transmission mechanism, and the image forming unit that forms an image on a sheet. The first rotation period of the stirring member detected by the detection unit after the control unit controls the switching mechanism of the transmission mechanism so that the stirring member rotates at a first speed at which the stirring member rotates. And said The second rotation period of the stirring member detected by the detection unit after the control unit controls the switching operation of the transmission mechanism so that the stirring member rotates at a second speed slower than the first speed. An abnormality determination that determines that the speed change mechanism is abnormal when the comparison determination unit determines that the first rotation period and the second rotation period coincide with each other. A part.

  According to the image forming apparatus of claim 1, when the detected first rotation period and second rotation period of the stirring member coincide with each other, the first speed and the second speed at which the stirring member rotates cannot be switched. It is thought that occurred. Accordingly, when it is determined that the first rotation period and the second rotation period coincide with each other even though the speed at which the stirring member rotates is switched by the transmission mechanism, it is determined that the transmission mechanism is abnormal. be able to. That is, the abnormality of the speed change mechanism can be determined by detecting the rotation period of the stirring member.

  The image forming apparatus according to claim 2, wherein the abnormality determining unit determines that the speed change mechanism is abnormal, and the first rotation period and the second rotation period are set to the first speed. In the case of the corresponding rotation cycle, a notification unit that notifies that the transmission mechanism is abnormal is provided.

  According to the image forming apparatus of the second aspect, when the speed change mechanism is abnormal and the first rotation period and the second rotation period are rotation periods according to the first speed, the speed change mechanism includes a stirring member. An abnormality has occurred in which the speed cannot be switched from the first speed to the second speed. By notifying that the transmission mechanism is abnormal, the user can recognize the abnormality of the transmission mechanism.

  According to a third aspect of the present invention, the notifying unit notifies that the image can be formed by the image forming unit.

  According to the image forming apparatus of the third aspect, the speed change mechanism cannot be switched from the first speed to the second speed, but at the first speed at which the stirring member rotates when the image forming unit forms an image on the paper. Since the stirring member can be rotated, the image forming unit can form an image on the paper. Therefore, by notifying that the image forming unit can form an image, the user can recognize that the speed change mechanism is abnormal but the image forming unit can form an image.

  According to a fourth aspect of the present invention, the notification unit notifies that the life of the developer is shortened.

  According to the image forming apparatus of the fourth aspect, since the speed change mechanism cannot be switched from the first speed to the second speed, the developer is stirred by the stirring member at the first speed. That is, the developer cannot be stirred at a second speed that is slower than the first speed. The developer has a shorter life when it is fast than when the stirring speed is slow. When the developer is stirred by the stirring member at the first speed, the life of the developer is shortened as compared with the case where the developer is stirred at the second speed. Therefore, the user can recognize that the life of the developer is shortened when the speed change mechanism has an abnormality in which the speed of the stirring member cannot be switched from the first speed to the second speed.

  The image forming apparatus according to claim 5, wherein the abnormality determination unit determines that the speed change mechanism is abnormal, and the first rotation period and the second rotation period are set to the second speed. In the case of the corresponding rotation cycle, a notification unit that notifies that the transmission mechanism is abnormal is provided.

  According to the image forming apparatus of the fifth aspect, when the speed change mechanism is abnormal and the first rotation period and the second rotation period are the rotation periods corresponding to the second speed, the speed change mechanism includes a stirring member. An abnormality has occurred in which the speed cannot be switched from the second speed to the first speed. By notifying that the transmission mechanism is abnormal, the user can recognize the abnormality of the transmission mechanism.

  Further, in the image forming apparatus according to claim 6, the notification unit notifies that the density at which the image forming unit forms an image on a sheet is reduced.

  According to the image forming apparatus of the sixth aspect, since the speed change mechanism cannot be switched from the second speed to the first speed, the agitating member rotates at a second speed slower than the first speed. When the image is formed on the paper by the image forming unit at the second speed, the developer supply amount is smaller than when the image is formed at the first speed, so that the density for forming the image on the paper is low. Become. Therefore, the user can recognize that the speed change mechanism is abnormal and that the density at which an image is formed on the paper is reduced.

  The image forming apparatus according to claim 7, wherein the control unit controls a switching operation of the transmission mechanism so that a speed at which the stirring member rotates during the initialization operation is set to a second speed, and the image forming apparatus performs the operation during the image formation. The switching operation of the transmission mechanism is controlled so that the rotation speed of the stirring member becomes the first speed.

  According to the image forming apparatus of the seventh aspect, the switching operation of the speed change mechanism is controlled so that the stirring member is rotated at the second speed during the initialization operation, and the stirring member is rotated at the first speed during image formation. Since the switching operation of the speed change mechanism is controlled, it is possible to determine whether the first rotation period and the second rotation period coincide with each other during image formation, and it is possible to determine an abnormality in the speed change mechanism.

  According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising: a driving source that generates a driving force; a photosensitive drum that carries a developer transferred to the paper; an exposure device that exposes the photosensitive drum; and the exposure device. A developer roller that supplies the developer to the exposed photosensitive drum to develop the photosensitive drum, and that rotates by obtaining a driving force from the driving source, and the stirring member includes a developer on the developing roller. The transmission mechanism is provided in a driving force transmission circuit from the driving source to the developing roller and the stirring member, and the control unit is configured to perform image formation. The switching operation of the transmission mechanism is controlled so that the first speed is achieved when the image forming operation is performed, and the switching operation of the transmission mechanism is controlled so that the second speed is achieved when image formation is not performed.

  According to the image forming apparatus of the eighth aspect, the rotation speed of the stirring member can be switched between when the image is formed and when the image is not formed.

  According to the present invention, it is possible to determine abnormality of the speed change mechanism.

It is a principal part sectional side view which shows the laser printer which concerns on embodiment of this invention. FIG. 2 is an enlarged side sectional view showing a developing unit according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line XX in FIG. 2 illustrating a toner storage chamber according to an embodiment of the present invention. (A) is a schematic diagram of the gear mechanism which concerns on the 1st Embodiment of this invention, (b) is a perspective view of the gear mechanism which concerns on 1st Embodiment of this invention. (A) And (b) is sectional drawing of the transmission mechanism which concerns on the 1st Embodiment of this invention. FIG. 3 is a schematic diagram illustrating a photosensitive drum and a drive transmission mechanism of a developing cartridge according to an embodiment of the present invention. It is a block diagram which shows the principal part structure of the control system of the laser printer which concerns on the 1st Embodiment of this invention. 4 is a timing chart of an output signal output from the light receiving unit of the photosensor according to the embodiment of the present invention, where (a) is a state where there is no toner and a state of a slow speed, and (b) is a state where the toner is (C) is a state where it is determined that the remaining amount of toner is low, and (d) is a state where it is determined that there is no toner. Slow state and (e) respectively show a state where there is no toner and a normal speed state. 5 is a flowchart for explaining an abnormality detection operation of a speed change mechanism of the image forming apparatus according to the embodiment of the present invention. It is a flowchart for demonstrating the operation | movement of the abnormality process which concerns on embodiment of this invention. It is a disassembled perspective view of the transmission mechanism which concerns on the 2nd Embodiment of this invention. It is a perspective view (the 1) of a gear mechanism concerning a 2nd embodiment of the present invention. It is a perspective view (the 2) of the gear mechanism concerning a 2nd embodiment of the present invention.

[First Embodiment]
Next, a first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, a case where the present invention is applied to a laser printer will be described.

(Whole structure of laser printer)
FIG. 1 is a side cross-sectional view showing a main part of a laser printer according to an embodiment of the present invention. In FIG. 1, a laser printer 1 includes a feeder unit 4 for supplying paper 3 and an image forming unit 5 for forming a predetermined image on the supplied paper 3 in a main body casing 2. . The feeder unit 4 includes a paper feed tray 41 that is detachably attached to the bottom of the main casing 2, a paper pressing plate 6 provided in the paper feed tray 41, and one end of the paper feed tray 41. A paper feed roller 7 and a paper feed pad 8 provided above, and a registration roller 9 provided downstream of the paper feed roller 7 in the transport direction of the paper 3 are provided.

  The sheet pressing plate 6 can stack the sheets 3 in a stacked manner, and is supported so that the end far from the sheet feeding roller 7 can swing, and the near end rotates in the vertical direction. It is made possible, and is biased upward by a spring (not shown) from the back side. Therefore, the sheet pressing plate 6 is rotated downward against the urging force of the spring with the end portion far from the sheet feeding roller 7 as a fulcrum as the amount of stacked sheets 3 increases. The paper feed roller 7 and the paper feed pad 8 are disposed to face each other, and the paper feed pad 8 is pressed toward the paper feed roller 7 by a spring 10 disposed on the back side of the paper feed pad 8. . The uppermost sheet 3 on the sheet pressing plate 6 is pressed toward the sheet feeding roller 7 by a spring (not shown) from the back side of the sheet pressing plate 6, and the sheet feeding roller 7 and the sheet feeding are rotated by the rotation of the sheet feeding roller 7. After being sandwiched between the pads 8, the sheets are fed one by one. The registration roller 9 is composed of two rollers on the driving side and the driven side, and the sheet 3 sent from the sheet feeding roller 7 is sent to the image forming unit 5 after a predetermined registration.

  The image forming unit 5 includes a scanner unit 11, a developing unit 12, and a fixing unit 13.

  The scanner unit 11 is provided in the upper part of the main casing 2 and includes a laser light emitting unit (not shown), a polygon mirror 14 that is driven to rotate, lenses 15 and 16, reflecting mirrors 17, 18 and 19, and the like. The laser beam based on the predetermined image data emitted from is passed or reflected in the order of the polygon mirror 14, the lens 15, the reflecting mirrors 17 and 18, the lens 16, and the reflecting mirror 19, as shown by a chain line, and will be described later. The surface of the photosensitive drum 21 of the developing unit 12 is irradiated with high-speed scanning.

  FIG. 2 is an enlarged side sectional view showing the developing unit according to the embodiment of the present invention. Next, the developing unit 12 will be described with reference to FIG. In FIG. 2, the developing unit 12 is disposed below the scanner unit 11, and is detachably attached to the main body casing 2, and the development is detachably attached to the drum cartridge 20. Cartridge 36. The drum cartridge 20 includes a photosensitive drum 21, a transfer roller 26, and a scorotron charger 25. Thus, the developing cartridge 36 is configured to be separable from the photosensitive drum 21 and the scorotron charger 25.

  The developing cartridge 36 is partitioned and formed into a developing chamber 51 for developing toner and a toner containing chamber 27 for containing toner. In the developing chamber 51, the developing roller 22 and a layer thickness regulating member are formed. The layer thickness regulating blade 23 and the supply roller 24 are accommodated. The toner storage chamber 27 of this embodiment is an example of a storage unit of the present invention.

  Further, the developing chamber 51 and the toner storage chamber 27 are partitioned by an upper partition wall 53 and a lower partition wall 54, and a width is provided between the upper partition wall 53 and the lower partition wall 54. A substantially rectangular opening 52 extending in the direction is formed. The opening 52 is opened so that the toner in the toner storage chamber 27 and the toner in the developing chamber 51 can circulate with each other. In the toner storage chamber 27, positively charged nonmagnetic one-component toner is stored as a developer.

  3 is a cross-sectional view taken along the line XX in FIG. 2 showing the toner storage chamber according to the embodiment of the present invention. In FIG. 3, for ease of explanation, the position of the agitator 29 and the wiper 39 described later is not in the position shown in FIG. 2 but in a vertical direction that is parallel to the upper partition wall 53. As shown. The agitator 29 of this embodiment is an example of the stirring member of the present invention.

  As shown in FIGS. 2 and 3, the toner storage chamber 27 is cleaned with an agitator 29 for agitating and supplying the toner from the opening 52 toward the developing chamber 51, and light transmission windows 58 and 59 described later. And a rotating shaft 28 that supports the agitator 29 and the wiper 39 are provided.

  As shown in FIG. 3, the rotation shaft 28 extends between both side walls 56 and 57 of the toner storage chamber 27 at substantially the center of the toner storage chamber 27, and one end thereof protrudes from one side wall 56 of the toner storage chamber 27. An agitator gear 44 for rotating the rotary shaft 28 is provided at the protruding end.

  As shown in FIGS. 2 and 3, the agitator 29 is provided on the rotary shaft 28 over the length direction thereof, and a support member 42 made of a resin extending radially outward from the rotary shaft 28; A film-like sliding contact member 43 made of polyethylene terephthalate or the like attached to the tip of the support member 42 is provided.

  The agitator 29 rotates in the toner storage chamber 27 by the rotation of the rotary shaft 28, and the sliding contact member 43 slides in a state where it is bent to the bottom surface of the toner storage chamber 27 formed in a substantially cylindrical shape. By contacting, the toner is pushed up, and the pushed up toner is discharged from the opening 52 to the developing chamber 51.

  In the rotation of the agitator 29, the support member 42 also pushes up the toner in the same manner as the sliding contact member 43, and thus receives a large resistance. However, in order to reduce the resistance due to the toner, Openings 45 are formed at predetermined intervals.

  Further, the wiper 39 is provided at both sides in the longitudinal direction of the rotary shaft 28 with a 180 ° interval around the rotary shaft 28 with respect to the agitator 29, and radially outward from the rotary shaft 28. A support member 46 made of resin extending toward the surface and a cleaning member 47 made of urethane rubber or the like provided at both end portions of the support member 46 are provided.

  The wiper 39 rotates in the toner storage chamber 27 by the rotation of the rotary shaft 28, and the cleaning member 47 comes into contact with the light transmission windows 58 and 59 along with the rotation, and the light transmission windows 58 and 59 are rotated. The toner adhering to the toner is wiped off. As described above, when the agitator 29 and the wiper 39 are supported on one rotating shaft 28, the light transmission windows 58 and 59 are always moved by the wiper 39 at every rotation period of the agitator 29 regardless of the rotation speed of the agitator 29. To be cleaned. Therefore, the remaining amount of toner can be accurately and reliably detected by the optical sensor 62 described later.

  As shown in FIG. 2, the agitator 29 is provided with a substantially fan-shaped light shielding plate 85. By providing such a light shielding plate 85, as will be described later, the length of light shielding by the optical sensor 62 in one rotation of the agitator 29 is defined longer, so that erroneous detection is lessened and more accurate. Detection has been achieved.

  On the other hand, in FIG. 2, in the developing chamber 51, the supply roller 24 is disposed on the side close to the opening 52 so as to be rotatable around the roller shaft 131 in the direction of the arrow, that is, counterclockwise. Opposite to the supply roller 24, the developing roller 22 is disposed so as to be rotatable in the direction of the arrow about the roller shaft 132. The supply roller 24 and the developing roller 22 are in contact with each other in a state where each of them is compressed to some extent.

  In the supply roller 24, a metal roller shaft 131 is covered with a roller made of a conductive foam material. In the developing roller 22, a metal roller shaft 131 is covered with a roller made of a conductive rubber material. Note that a predetermined developing bias is applied to the developing roller 22 so as to generate a potential difference between the developing roller 22 and the photosensitive drum 21.

  In addition, a layer thickness regulating blade 23 is disposed in the vicinity of the developing roller 22. This layer thickness regulating blade 23 includes a blade main body 37 made of a metal leaf spring material, and a semicircular pressing member 38 made of insulating silicone rubber provided at the tip of the blade main body 37. The end of the blade body 37 opposite to the pressing member 38 is supported by the frame of the developing cartridge 36 near the developing roller 22, and the pressing member 38 is pressed against the developing roller 22 by the elastic force of the blade body 37. It is comprised so that.

  The toner discharged from the opening 52 toward the developing chamber 51 is supplied to the developing roller 22 by the rotation of the supply roller 24. At this time, the toner is positively charged between the supply roller 24 and the developing roller 22 by friction. Further, the toner supplied onto the developing roller 22 enters between the pressing member 38 of the layer thickness regulating blade 23 and the developing roller 22 as the developing roller 22 rotates. Here, the pressing member 38 and the developing roller 22 are rubbed and sufficiently charged by friction, and are carried on the developing roller 22 as a thin layer having a constant thickness.

  The toner rubbed between the pressing member 38 of the layer thickness regulating blade 23 and the developing roller 22 has an external additive such as silica added to the toner embedded in the toner base particles. As a result, the fluidity is lowered or the chargeability is lowered. Therefore, at the time of image formation, it is necessary to keep the rotational speed of the agitator 29 at a fixed speed or higher and efficiently circulate the toner in the developing cartridge 36 to prevent poor image formation due to the staying of deteriorated toner.

  A drive system for such a developing cartridge 36 will be described with reference to FIG. 4A is a schematic view of the gear mechanism according to the first embodiment of the present invention, and FIG. 4B is a perspective view of the gear mechanism according to the first embodiment of the present invention. In the present embodiment, the photosensitive drum 21, the developing roller 22, and the agitator 29 rotate by obtaining a driving force from one main motor 78 via a gear mechanism including a plurality of gears. The main motor 78 of this embodiment is an example of the drive source of the present invention.

  The gear mechanism 90 that transmits the driving force of the main motor 78 to the developing roller 22 and the agitator 29 rotates the developing roller 22 and the agitator 29 at the first speed as shown in FIG. A transmission mechanism 100 is provided for switching between the case where the developing roller 22 and the agitator 29 are rotated at a slow second speed. Hereinafter, the first speed is referred to as a normal speed, and the second speed is referred to as a slow speed.

  A path indicated by a solid line in FIG. 4A indicates a driving force transmission circuit for driving the developing roller 22 and the agitator 29 at a normal speed, and a path indicated by a two-dot chain line in FIG. 4 shows a driving force transmission circuit for rotating the developing roller 22 and the agitator 29 at a slow speed.

  In this embodiment, the normal speed is higher than the speed of the photosensitive drum 21, the slow speed is lower than the speed of the photosensitive drum 21, and the photosensitive drum 21 rotates at a constant speed regardless of the operating state of the transmission mechanism 100. It is set to be.

  As shown in FIG. 4A, the gear mechanism 90 decelerates the driving force output from the main motor 78 and transmits it to the transmission mechanism 100, and the driving force output from the transmission mechanism 100. Is composed of a developing roller 22 and a gear 95 for transmitting to the agitator 29.

  The gear 91 is a driving gear that receives the driving force from the main motor 78 and transmits the driving force to the distributing gear 92. The distributing gear 92 has three types arranged coaxially as shown in FIG. The gears 92A to 92C are integrated three-stage gears, and the driving force transmitted from the driving gear 91 is distributed to the driving force transmission circuit for normal speed and the driving force transmission circuit for slow speed.

  Specifically, the gear 92A of the distribution gear 92 is a driven gear that meshes with the drive gear 91, the gear 92B is a driven gear that transmits driving force to the first input gear 100A side of the transmission mechanism 100, and the gear 92C is The driven gear transmits the driving force to the second input gear 100B side of the speed change mechanism 100.

  The gear 92B of the distribution gear 92 transmits a driving force to the first input gear 100A via the first intermediate gear 93, and the gear 92C of the distribution gear 92 is transmitted to the second input gear via the second intermediate gear 94. The driving force is transmitted to 100B.

  For this reason, when the main motor 78 rotates, the gears 91 to 94 rotate in conjunction with the rotation of the main motor 78, so that the first input gear 100 </ b> A and the second input gear 100 </ b> B of the transmission mechanism 100 are also interlocked with the rotation / stop of the main motor 78. Rotate and stop. That is, the first input gear 100 </ b> A and the second input gear 100 </ b> B rotate / stop in conjunction with the rotation / stop of the main motor 78 regardless of the state of the transmission mechanism 100.

  The detailed structure of the speed change mechanism 100 will be described with reference to FIG. FIGS. 5A and 5B are sectional views of the speed change mechanism according to the first embodiment of the present invention. As shown in FIG. 5A, the transmission mechanism 100 includes a first input gear 100A, a second input gear 100B, an output gear 100C, a one-way clutch 101, an electromagnetic clutch 75, and the like.

  The first input gear 100A is a first input unit for rotating the developing roller 22 and the agitator 29 at a normal speed, and the second input gear 100B rotates the developing roller 22 and the agitator 29 at a slow speed. The output gear 100C rotates by obtaining a driving force from the first input gear 100A or the second input gear 100B, meshes with the gear 95, and is driven to the developing roller 22 and the agitator 29 side. This is an output unit that outputs force.

  A rotary shaft 103 is integrated with the output gear 100C. The rotary shaft 103 extends in the axial direction and penetrates the first input gear 100A and the second input gear 100B, and the second input gear. 100B and one-way clutch 101 are connected.

  For this reason, in the driving force transmission circuit from the second input gear 100B to the output gear 100C, only the rotational force from the second input gear 100B to the output gear 100C is transmitted to the rotary shaft 103 by the one-way clutch 101, and the output gear Transmission of rotational force from 100C toward the second input gear 100B is interrupted.

  Further, the rotor coil 102A of the electromagnetic clutch 75 is engaged through a spline (see JIS D 2001, etc.), a serration (see JIS B 1602, etc.), etc. provided on the rotary shaft 103. It can be displaced in the axial direction while rotating integrally.

  On the other hand, the armature 102B that forms the fixed iron core of the electromagnetic clutch 75 is integrated with the first input gear 100A, and the first input gear 100A is rotatably assembled to the rotary shaft 103 via a bearing (not shown). It has been.

  Therefore, as shown in FIG. 5 (a), when the rotor coil 102A is energized, the rotor coil 102A is attracted to the armature 102B by the electromagnetic attractive force, and the rotor coil 102A and the armature 102B are integrated. Since the driving force transmitted from the gear 100A is transmitted to the rotating shaft 103, the driving force transmission circuit from the first input gear 100A to the output gear 100C is connected.

  At this time, the normal driving force transmitted from the first input gear 100A and the slow driving force transmitted from the second input gear 100B act on the rotating shaft 103. The slow driving force is greater than the normal driving force. Since the rotational speed is low, when viewed from the rotating shaft 103, the slow driving force tries to rotate the rotating shaft 103 in the direction opposite to the rotating direction by the normal driving force, so the transmission of the slow driving force is blocked by the one-way clutch 101. Is done.

  For this reason, when the rotor coil 102A is energized, only the normal driving force is transmitted to the rotating shaft 103, so that the developing roller 22 and the agitator 29 rotate at the normal speed.

  On the other hand, when the energization of the rotor coil 102A is cut off, the electromagnetic attractive force disappears, and the transmission of the driving force transmitted from the first input gear 100A to the output gear 100C is cut off. Only the slow driving force is transmitted to the rotating shaft 103 (see FIG. 5B), and the developing roller 22 and the agitator 29 rotate at a slow speed.

  Next, the drive transmission mechanism for the photosensitive drum 21 and the developing cartridge will be described with reference to FIG. FIG. 6 is a schematic diagram showing a photosensitive drum and a drive transmission mechanism for the developing cartridge according to the embodiment of the present invention.

  As shown in FIG. 6, a drum drive transmission mechanism 111 for rotationally driving the photosensitive drum 21 is provided on one side wall of the drum cartridge 20. A developing drive transmission mechanism 112 for rotationally driving the supply roller 24, the developing roller 22, and the agitator 29 is provided on one side wall of the developing cartridge 36.

  The drum drive transmission mechanism 111 includes a drum gear 113 that is directly connected to the roller shaft 130 of the photosensitive drum 21, and a drum drive gear 114 that meshes with the drum gear 113.

  With the drum cartridge 20 mounted on the main casing 2, an input gear (not shown) provided in the main casing 2 meshes with the drum driving gear 114, and the driving force from the main motor 78 provided in the main casing 2 is The drum is input to the drum drive gear 114 via the input gear. The driving force input to the drum driving gear 114 is transmitted to the drum gear 113 and rotates the photosensitive drum 21 integrally with the drum gear 113.

  The development drive transmission mechanism 112 includes a supply roller gear 115 directly connected to the roller shaft 131 of the supply roller 24, a development roller gear 116 directly connected to the roller shaft 132 of the development roller 22, and the supply roller gear 115 and A first idle gear 117 that meshes with the developing roller gear 116, a second idle gear 118 that is provided coaxially with the first idle gear 117 and has a smaller diameter than the first idle gear 117, and a second idle gear A third idle gear 119 that meshes with the gear 118, a fourth idle gear 120 that is provided coaxially with the third idle gear 119 and has a smaller diameter than the third idle gear 119, and the fourth idle gear 120. And an agitator gear 44 that is directly coupled to the rotating shaft 28 of the agitator 29, a first idle gear 117, and a second A coupling female member 122 is provided coaxially with the idle gear 118 and to which a coupling male member (not shown) is coupled. The coupling male member is provided coaxially with the gear 95 and transmits the driving force output from the gear 95 to the developing roller 22 and the agitator 29 side to the coupling female member 122.

  The coupling female member 122 is coupled to the coupling male member in a state where the developing cartridge 36 is mounted on the main casing 2, and the driving force from the main motor 78 is coupled via the transmission mechanism 100 and the coupling male member. Input to the ring female member 122. The driving force input to the coupling female member 122 rotates the first idle gear 117 and the second idle gear 118 integrally with the coupling male member. When the first idle gear 117 rotates, the supply roller gear 115 and the developing roller gear 116 rotate, and thereby the supply roller 24 and the developing roller 22 rotate. When the second idle gear 118 is rotated, the third idle gear 119 is rotated, and the fourth idle gear 120 is rotated integrally with the third idle gear 119. Then, the rotation of the fourth idle gear 120 is transmitted to the agitator gear 44, and the agitator 29 rotates as the agitator gear 44 rotates.

  Further, as shown in FIG. 2, the photosensitive drum 21 is rotatable around the roller shaft 130 in the direction of the arrow, that is, in the clockwise direction in a state of being in contact with the developing roller 22 on the side of the developing roller 22. It is arranged. The photosensitive drum 21 has a drum main body grounded and a surface formed of a positively chargeable material such as an organic photosensitive member mainly composed of polycarbonate. The scorotron charger 25 is disposed above the photosensitive drum 21 at a predetermined interval. The scorotron charger 25 is a positively charged scorotron charger that generates corona discharge from a charging wire such as tungsten, and is configured so that the surface of the photosensitive drum 21 can be uniformly positively charged. Has been.

  The surface of the photosensitive drum 21 is uniformly positively charged by the scorotron charger 25 and then exposed by high-speed scanning of the laser beam from the scanner unit 11 to form an electrostatic latent image based on predetermined image data. Is done. The electrostatic latent image formed on the surface of the photosensitive drum 21 when the positively charged toner carried on the developing roller 22 comes into contact with the photosensitive drum 21 by the rotation of the developing roller 22. In other words, the surface of the photosensitive drum 21 that is uniformly positively charged is visualized by selectively transferring to the portion of the photosensitive drum 21 that is exposed to the laser beam and the potential of which is lowered. Achieved. The scanner unit 11 of this embodiment is an example of an exposure device of the present invention.

  A transfer roller 26 facing the photosensitive drum 21 is disposed below the photosensitive drum 21 so as to be rotatable in the arrow direction, that is, in the counterclockwise direction. In the transfer roller 26, a roller made of a conductive rubber material is covered on a metal roller shaft, and a predetermined transfer bias is applied. Therefore, the toner developed on the photosensitive drum 21 is transferred to the sheet 3 while the sheet 3 passes between the photosensitive drum 21 and the transfer roller 26.

  Further, as shown in FIG. 1, the fixing unit 13 is disposed on the side downstream side of the developing unit 12, the heating roller 32, the pressing roller 31 pressed against the heating roller 32, and the heating roller 32 and the pressing unit. A pair of conveying rollers 33 provided on the downstream side of the roller 31 is provided. The heating roller 32 is made of a metal and includes a halogen lamp for heating, and the toner transferred onto the paper 3 in the developing unit 12 is passed while the paper 3 passes between the heating roller 32 and the pressing roller 31. Then, the paper 3 is conveyed to a pair of paper discharge rollers 34 by a conveyance roller 33. The paper 3 sent to the pair of paper discharge rollers 34 is discharged onto the paper discharge tray 35 by the paper discharge rollers 34.

  Further, the laser printer 1 is provided with an optical sensor 62 as a remaining amount detection sensor for detecting the remaining amount of toner remaining in the toner storage chamber 27.

  As shown in FIG. 7 described later, the optical sensor 62 includes a light emitting unit 60 including a light emitting element and a light receiving unit 61 including a light receiving element. That is, in FIG. 3, light transmission windows 58 for transmitting light of the optical sensor 62 to both side walls 56 and 57 of the toner storage chamber 27 at an appropriate position closer to the opening 52 from the center of the toner storage chamber 27. And 59 are provided so as to face each other, and the light emitting portion 60 and the light receiving portion 61 are attached to the frames 63 and 64 of the main casing 2 facing the light transmitting windows 58 and 59, respectively.

  More specifically, a lens 65 is embedded in the frame 63 facing one light transmission window 58, and a support substrate 69 is supported via a holder member 67 at a position facing the lens 65 outwardly. The light emitting unit 60 is provided on the support substrate 69 such that the light emitting element faces the lens 65. In addition, a lens 66 is embedded in the frame 64 facing the other light transmission window 59, and a support substrate 70 is supported via a holder member 68 at a position facing the outside of the lens 66. The light receiving unit 61 is provided on the support substrate 70 such that the light receiving element faces the lens 66.

  In FIG. 3, the case portion 40 of the drum cartridge 20 appears in a substantially concave shape so as to surround the lower side of the developing cartridge 36, but both sides of the case portion 40 facing the light transmission windows 58 and 59, respectively. Openings 71 and 72 are also formed in the wall.

  Therefore, the light emitting unit 60, the lens 65, the opening 71, and the light transmission window 58, and the light receiving unit 61, the lens 66, the opening 72, and the light transmission window 59 are arranged in a straight line with the toner storage chamber 27 in between. Thus, highly directional light emitted from the light emitting unit 60 passes through the toner storage chamber 27 via the lens 65, the opening 71 and the light transmission window 58, and passes through the light transmission window 59, the opening 72 and Light is received by the light receiving unit 61 via the lens 66.

(Electric configuration of laser printer)
Next, the electrical configuration of the laser printer 1 will be described with reference to FIG. FIG. 7 is a block diagram showing the main configuration of the control system of the laser printer according to the first embodiment of the present invention. In FIG. 7, in the laser printer 1, the ROM 80, the RAM 81, the operation panel unit 82, the interface 83, the main motor 78, the electromagnetic clutch 75, the light emitting unit 60, and the light receiving unit 61 are connected to the CPU 79 via the bus 84. ing. The main motor 78 and the electromagnetic clutch 75 are controlled by the CPU 79 and the like.

  The ROM 80 stores various programs for forming an image in the laser printer 1, a toner remaining amount detection program, an agitator drive control program, and the like which will be described later. The RAM 81 temporarily stores numerical values set in various programs. The operation panel unit 82 is provided with input keys for operating the laser printer 1 and LEDs for displaying various settings. The interface 83 monitors data transmitted / received to / from an external device such as a personal computer. The operation panel unit 82 of the present embodiment is an example of a notification unit of the present invention.

(Toner remaining amount detection control)
Next, control for detecting the remaining amount of toner in such a control system will be described with reference to FIG. FIG. 8 is a timing chart of an output signal output from the light receiving unit of the optical sensor according to the embodiment of the present invention. FIG. 8A is a state where there is no toner and a state of a slow speed, and FIG. Is a state where the toner is sufficient and is in a slow speed state, (c) is a state where the remaining amount of toner is determined to be low, and a state where the toner is in a slow speed, and (d) is determined that there is no toner. (E) shows a state where there is no toner and a normal speed state. The toner remaining amount detection is performed by processing of a toner remaining amount detection program stored in the ROM 80. That is, in this toner remaining amount detection program, the voltage output from the light receiving element changes according to the amount of light received by the light receiving unit 61, and the change in the voltage output from the light receiving unit 61 is recognized as an output signal. The remaining amount of toner is detected from the change of the output signal per predetermined rotation period of the agitator 29. More specifically, when the light emitted from the light emitting unit 60 is received by the light receiving unit 61 without being blocked in the toner storage chamber 27, the amount of received light is large and is output from the light receiving unit 61. Since the voltage is lowered, this is recognized as an output signal of “LOW” level. On the other hand, when the light emitted from the light emitting unit 60 is blocked in the toner storage chamber 27, the amount of received light is small and the voltage output from the light receiving unit 61 is high. As an output signal. By detecting the change in the output voltage, it is possible to detect whether or not the light passing through the toner storage chamber 27 is blocked by the remaining toner. For example, the high output voltage is 5V and the low output voltage is 0V.

  On the other hand, since the light emitted from the light emitting unit 60 is periodically blocked by the rotation of the agitator 29, the output signal is shown in FIG. 8A in synchronization with the rotation of the agitator 29 in the absence of toner. As described above, the “HIGH” level and the “LOW” level are alternately and periodically repeated at a predetermined ratio. On the other hand, in the state where the toner is sufficient, the light emitted from the light emitting unit 61 and passing through the toner storage chamber 27 is blocked by the toner for all the time, so that only the “HIGH” level is obtained as shown in FIG. Is continuous. Thus, it is possible to accurately and reliably detect that the toner does not have to be replenished.

  As the image forming operation proceeds, if the amount of toner decreases, the light emitted from the light emitting unit 61 is blocked only when the toner remaining in the toner storage chamber 27 is pushed up by the rotation of the agitator 29. The “HIGH” level and the “LOW” level are periodically alternately repeated at a predetermined ratio. At this time, when the amount of pushed-up toner is large, the light is blocked for a longer time, and the ratio of the “HIGH” level to the “LOW” level is long as shown in FIG. As the image forming operation proceeds and the amount of toner decreases, the time during which light is blocked is shortened, and the ratio of the “HIGH” level to the “LOW” level is shortened.

  Therefore, in this toner remaining amount detection program, as shown in FIG. 8A, the ratio of the “LOW” level period T1 in the predetermined rotation period, which is the period T2 in which the agitator 29 rotates three times, is calculated. The remaining amount is detected. More specifically, as shown in FIG. 8C, when the ratio of the “LOW” level exceeds 2% with respect to the ratio of the “LOW” level during normal image formation, the remaining toner remains. It is determined that the amount is small, a warning indicating that the remaining amount of toner is low is displayed on the LED of the operation panel unit 82, and the ratio of the “LOW” level is 18% as shown in FIG. Is exceeded, it is determined that there is no toner, a warning indicating that there is no toner is displayed on the LED of the operation panel unit 82, and the drive of the main motor 78 is stopped.

  Therefore, the remaining amount of toner can be detected accurately and reliably by detecting the length of light blocking time or transmission time of the light connecting the light emitting unit 60 and the light receiving unit 61 by this toner remaining amount detecting program.

  The processing of the toner remaining amount detection program is executed at an appropriate timing such as when the laser printer 1 is turned on, at the start and end of the image forming operation, and during the continuous image formation.

  For example, when the speed of the laser printer 1 is to be increased, the toner is efficiently circulated in the developing cartridge 36 by rotating the agitator 29 at a normal speed, so that more toner with good charging efficiency can be developed. However, when the agitator 29 is rotated at a normal speed, the toner flies in the toner storage chamber 27, and the flicked toner blocks the light emitted from the light emitting unit 61. There is. In such a case, even when the remaining amount of toner is low, erroneous detection of the remaining amount of toner occurs due to light shielding by the flying toner.

  In particular, in this laser printer 1, polymerized toner is used, and due to its good fluidity, when the agitator 29 is rotated at a normal speed, it becomes easier to behave than when it is rotated at a slow speed.

  For this reason, in the laser printer 1, when detecting the remaining amount of toner, the agitator 29 is rotated at a slow speed to prevent the toner from flying in the toner storage chamber 27, thereby accurately detecting the remaining amount of toner. On the other hand, at the time of image formation, the agitator 29 is rotated at a normal speed to efficiently circulate the toner in the developing cartridge 36 to prevent the retention of toner deteriorated due to rubbing by the layer thickness regulating blade 23, etc. The toner charging efficiency is improved and more toner is supplied to the developing roller 22.

More specifically, this control is performed by processing of an agitator drive control program stored in the ROM 80. That is, the processing of the agitator drive control program is executed in synchronization with the processing of the remaining toner amount detection program, and while the remaining toner amount detection program is being executed, the electromagnetic clutch 75 is turned off and the agitator 29 is thrown. While the toner remaining amount detection program is not being executed, the electromagnetic clutch 75 is turned on so that the agitator 29 is rotated at the normal speed. While the toner remaining amount detection program is not executed, an output signal as shown in FIG. FIG. 8E is a timing chart of an output signal output from the light receiving unit 61 of the optical sensor 62 when there is no toner in the toner storage chamber 27 when the rotation of the agitator 29 is controlled at the normal speed. . A period T4 from the time when the “HIGH” level is changed to the “LOW” level to the time when the “LOW” level is changed to the “LOW” level after the “LOW” level period T3 is measured three times is measured. The period T4 is a period during which the agitator 29 rotates three times at the normal speed. Rotational speed of the agitator 29, more specifically, for example, in the case of the normal rate, 90.1Min ^-1, in the case of the slow speed is 45.5Min ^-1, the slow speed from the normal speed The speed is reduced to about 1/2.

  By calculating the rotation cycle per rotation from the period T2, the rotation cycle TP1 that rotates once when the agitator 29 is controlled at the slow speed is calculated. Similarly, by calculating the rotation period per one rotation from the period T4, the rotation period TP2 for one rotation when the agitator 29 is controlled at the normal speed is calculated.

  By controlling the rotational speed of the agitator 29 by such processing of the agitator drive control program, it is possible to easily and reliably achieve the accurate detection of the remaining amount of toner and the formation of a good image. It is possible to sufficiently cope with the increase in the image forming speed.

(Transmission mechanism abnormality detection operation)
The abnormality detection operation of the transmission mechanism 100 will be described with reference to FIG. FIG. 9 is a flowchart for explaining the abnormality detection operation of the speed change mechanism of the image forming apparatus according to the embodiment of the present invention. A program for executing control of this abnormality detection operation is stored in the ROM 80.

  9 is started when the power of the laser printer 1 is turned on. When the laser printer 1 is turned on and the initialization operation is started (S101), the CPU 79 turns off the electromagnetic clutch 75 and starts energizing the main motor 78. That is, in order to switch to the slow speed, the CPU 79 controls the ON state and the OFF state of the electromagnetic clutch 75 to the OFF state, and rotates the developing roller 22 and the agitator 29 at the slow speed (S102). Examples of the initialization operation include fixing device temperature adjustment and rotation.

  Next, when the agitator 29 is controlled to rotate at a slow speed, measurement of the rotation period of the agitator 29 is started (S103). When the rotation period TP1 of the agitator 29 is detected by the optical sensor 62 and the detected rotation period TP1 is stored in the RAM 81, the measurement of the rotation period TP1 ends (S104: Yes). Until the rotation period TP1 of the agitator 29 is detected by the optical sensor 62, it is determined that the measurement of the rotation period TP1 is not completed (S104: No). After the measurement of the rotation period TP1 is finished (S104: Yes), the initialization operation is finished (S105).

  Thereafter, the CPU 79 receives an image formation start command transmitted from a personal computer or the like, and when the image forming operation is started (S106), the electromagnetic clutch 75 is turned on and the speed of the developing roller 22 and the agitator 29 is increased. To normal speed. That is, in order to switch from the slow speed to the normal speed, the CPU 79 controls the ON state and the OFF state of the electromagnetic clutch 75 to turn on and rotates the agitator 29 at the normal speed (S107). Note that the start timing of the image forming operation is, for example, a timing for instructing to start feeding the feeder unit 4. When the image forming operation is started in S <b> 106, the sheet 3 is fed from the feeder unit 4, the electrostatic latent image on the photosensitive drum 21 is transferred to the sheet 3 being conveyed by the transfer roller 26, and is thermally fixed by the fixing unit 13. As a result, an image is formed on the paper 3, and the paper 3 is discharged onto the paper discharge tray 35. S102, S107, and CPU 79 of this embodiment are examples of the control unit of the present invention.

  When this image forming operation is performed, that is, when the agitator 29 is controlled to rotate at the normal speed, measurement of the rotation period TP2 of the agitator 29 is started (S108). For example, when an image is formed on the first sheet, measurement of the rotation period TP2 is started at the timing when the agitator 29 is rotated in order to stir the toner and supply it to the developing roller 22. When the rotation period TP2 of the agitator 29 is detected by the optical sensor 62 and the detected rotation period TP2 is stored in the RAM 81, the CPU 79 ends the measurement of the rotation period TP2 (S109: Yes). Until the rotation period TP2 of the agitator 29 is detected by the optical sensor 62, it is determined that the measurement of the rotation period TP2 is not completed (S109: No). When the measurement of the rotation period TP2 of the agitator 29 is completed (S109: Yes), the process proceeds to S110. The end of the measurement of the rotation period TP2 is the timing when the period T4 in which the agitator 29 rotates three times at the normal speed after the measurement of the rotation period TP2 is started. S103, S104, S108, S109, the optical sensor 62, and the CPU 79 of this embodiment are examples of the detection unit of the present invention.

  Next, in S110, it is determined whether or not the rotation period TP1 and the rotation period TP2 stored in the RAM 81 match. When the rotation cycle TP1 and the rotation cycle TP2 coincide with each other, it is determined that the rotation speed of the agitator 29 cannot be switched by the transmission mechanism 100. The abnormality of the speed change mechanism 100 is, for example, when a foreign object is mixed between the rotor coil 102A and the armature 102B of the electromagnetic clutch 75, although the rotor coil 102A and the armature 102B are not adsorbed. This is caused by the fact that 102A and armature 102B rotate in synchronization. When such an abnormality occurs, the rotational speed of the agitator 29 becomes a normal speed and cannot be switched to the slow speed. Further, the abnormality of the speed change mechanism 100 occurs, for example, when the signal line for energizing the electromagnetic clutch 75 is disconnected, so that the rotor coil 102A and the armature 102B are not attracted. When such an abnormality occurs, the rotational speed of the agitator 29 becomes a slow speed and cannot be switched to the normal speed. S110 of this embodiment and CPU79 are examples of the comparison judgment part of the present invention.

  If the rotation cycle TP1 and the rotation cycle TP2 do not match, it is determined that the speed change mechanism 100 is operating normally. Therefore, it is possible to detect an abnormality in the speed change mechanism 100 by determining whether or not the rotation cycle TP1 and the rotation cycle TP2 match. If it is determined that the rotation cycle TP1 and the rotation cycle TP2 do not match (S110: No), the transmission mechanism 100 is assumed to be operating normally, and the processing of this flowchart ends. If it is determined that the rotation period TP1 and the rotation period TP2 match (S110: Yes), the CPU 79 determines that the speed change mechanism 100 is abnormal and proceeds to the process of S201. The CPU 79 and S110: Yes in this embodiment are examples of the abnormality determination unit of the present invention.

  In S201, the abnormality process shown in FIG. 10 is started. FIG. 10 is a flowchart for explaining the operation of the abnormality process according to the embodiment of the present invention. When the abnormality process is started, the fact that the speed change mechanism 100 is abnormal is displayed on the LED of the operation panel unit 82 (S202). Next, it is determined whether the rotation period TP1 and the rotation period TP2 are rotation periods corresponding to the slow speed or rotation periods corresponding to the normal speed (S203). When the rotation cycle TP1 and the rotation cycle TP2 are rotation cycles corresponding to the slow speed (S203: Yes), the LED of the operation panel unit 82 is displayed that the image formation density is reduced (S204). When an abnormality occurs in the speed change mechanism 100 and the rotation speed of the developing roller 22 and the agitator 29 cannot be switched from the slow speed to the normal speed, the photosensitive drum 21 rotates at a normal speed when the image forming operation is performed. The developing roller 22 rotates at a slow speed slower than the normal speed. The amount of toner supplied from the developing roller 22 to the photosensitive drum 21 is smaller when the developing roller is rotating at the slow speed than when the developing roller 22 is rotating at the normal speed. That is, the density of image formation is reduced by the amount of toner, and this affects the quality of image formation. Therefore, the user can perform the image forming operation by recognizing that the quality of the image formation is affected.

  Next, the CPU 79 determines whether or not to stop image formation (S205). Whether or not to stop image formation is determined by an input to the operation panel unit 82 by the user. When continuation of image formation is input (S205: No), the process proceeds to S209. By inputting the continuation of the image formation, the image forming operation can be continued even if the density of the image formation is reduced and the quality of the image formation is affected. Even if the quality of image formation is affected, it is convenient for the user who obtains the image formation result. If the image forming operation is continued in S209, the abnormality process is terminated.

  When cancellation of image formation is input (S205: Yes), the process proceeds to S206. Since the density of image formation becomes light and affects the quality of image formation, it is possible to prevent unnecessary image formation from being performed by inputting stop of image formation. This is convenient for users who demand image forming quality. In S206, the image formation is stopped and the abnormality process is terminated.

  Further, when the rotation cycle TP1 and the rotation cycle TP2 are rotation cycles corresponding to the normal speed (S203: No), it is displayed on the LED of the operation panel unit 82 that the image forming operation can be continued (S207). ). Further, the fact that the life of the toner is shortened is displayed on the LED of the operation panel unit 82 (S208). As for the life of the toner, the number of times the toner is agitated is larger at the normal speed than at the slow speed, so that the effect of suppressing the deterioration of the toner is reduced and the life is shortened. Next, when the image forming operation is continued in S209, the abnormality process (S201) is ended, and the process returns to the process of the flowchart of FIG.

  When the image forming operation is finished (S111), the process of the flowchart of the abnormality detection operation of the transmission mechanism 100 is finished. After the image forming operation is completed, the speed of the agitator 29 may be switched from the normal speed to the slow speed. The speed of the agitator 29 may be switched from the normal speed to the slow speed after the development of the photosensitive drum 21 is completed.

  As described above, since the rotation cycle of the agitator 29 is detected by using the optical sensor 62 without providing a dedicated sensor for detecting the rotation cycle of the agitator 29, an increase in the number of parts can be suppressed.

[Second Embodiment]
A second embodiment will be described with reference to FIGS. 11, 12, and 13. FIG. FIG. 11 is an exploded perspective view of the speed change mechanism according to the second embodiment of the present invention. 12 and 13 are perspective views of a gear mechanism according to the second embodiment of the present invention. In the second embodiment, the internal configuration of the laser printer shown in FIG. 1 in the first embodiment, the internal configuration of the developing unit shown in FIG. 2, the internal configuration of the toner storage chamber shown in FIG. 3, and the photosensitive drum shown in FIG. First, a drive transmission mechanism of the developing cartridge, an output signal output from the light receiving portion of the optical sensor shown in FIG. 8, an abnormality detection operation of the speed change mechanism shown in FIG. 9, and an abnormality processing operation shown in FIG. Common with form. The description of the configuration common to the first embodiment is omitted. The main configuration of the control system of the laser printer according to the second embodiment is configured by replacing the electromagnetic clutch 75 with the solenoid 104 in the main configuration of the control system of the laser printer shown in FIG. Common. In the first embodiment, the speed change mechanism 100 is configured by the electromagnetic clutch 75. However, in the second embodiment, the speed change mechanism 100 is configured by the planetary gear mechanism as shown in FIG. 11, and the solenoid shown in FIG. The state of the sun gear 105A of the planetary gear mechanism is switched by 104.

  That is, as shown in FIG. 11, the planetary gear mechanism is configured to rotate while rotating with the sun gear 105A and the sun gear 105A being engaged with the sun gear 105A, and rotating the planetary gears 105B and the planetary gears 105B. The carrier gear 105C is rotatably supported and rotated by receiving a driving force from the main motor 78, and the inner gear 105D is disposed coaxially with the sun gear 105A and meshes with the planetary gear 105B. ing.

  In addition, the rotation shaft 105E that rotates integrally with the sun gear 105A cooperates with the first output gear 105F and the solenoid 104 to switch between allowing and restricting the rotation of the sun gear 105A. 105G is provided.

  When the solenoid 104 is energized and turned ON, as shown in FIG. 12, the latching claw 105H is engaged with the ratchet gear 105G, the rotation of the sun gear 105A is restricted, and the energization to the solenoid 104 is interrupted. Then, as shown in FIG. 13, the engagement between the ratchet gear 105G and the locking claw 105H is released, and the sun gear 105A can freely rotate.

  The internal gear 105D is provided with a second output gear 105J that rotates integrally with the internal gear 105D and meshes with the gear 95. On the other hand, the first output gear 105F meshes with the large-diameter portion 106A of the two-stage gear 106 incorporating the one-way clutch 101, and the small-diameter portion 106B of the two-stage gear 106 meshes with the gear 95 via the intermediate gear 107. ing.

  Then, when the carrier gear 105C rotates in response to the driving force from the main motor 78 in a state where the rotation of the sun gear 105A is restricted, the driving force is decelerated to the normal speed and transmitted to the internal gear 105D. Is transmitted to the gear 95.

  At this time, the driving force of the gear 95 is transmitted to the small-diameter portion 106B of the two-stage gear 106 via the intermediate gear 107, but the first output gear 105F is received by the one-way clutch 101 built in the two-stage gear 106. Transmission to the side is cut off.

  On the other hand, when the carrier gear 105C is rotated by receiving the driving force from the main motor 78 with the sun gear 105A being rotatable, the direction of rotation of the second output gear 105 and the direction of rotation of the first output gear 105F are changed. Since it is in the reverse direction, the first output gear 105F rotates in conjunction with the rotation of the carrier gear 105C, and the driving force is a slow speed via the two-stage gear 106 and the intermediate gear 107 as shown in FIG. Until it is decelerated and transmitted to the gear 95.

  Note that the switching timing between the slow speed and the normal speed, that is, the ON / OFF switching timing of the solenoid 104 is controlled by the CPU 79 at the same timing as in the first embodiment.

  Using such a configuration, the abnormality detection operation of the speed change mechanism 100 shown in FIG. 9 is performed as in the first embodiment. In the second embodiment, when the speed of the speed change mechanism 100 cannot be switched, for example, the locking claw 105H is damaged, and the engagement between the ratchet gear 105G and the locking claw 105H is released and the sun gear 105A is released. Is caused by being freely rotatable. When such an abnormality occurs, the rotational speed of the agitator 29 becomes a slow speed and cannot be switched to the normal speed. Further, for example, since the signal line for energizing the solenoid 104 is disconnected, the solenoid 104 is turned off, the engagement between the ratchet gear 105G and the locking claw 105H is released, and the sun gear 105A is free. It is caused by being able to rotate. Therefore, when such an abnormality occurs, the rotational speed of the agitator 29 becomes a slow speed and cannot be switched to the normal speed.

[Modification]
The present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention. An example of the modification will be described below.

  In the present embodiment, the case where the slow speed is used as the second speed according to the present invention has been described. However, the second speed according to the present invention may be a speed at which the rotation of the agitator 29 is stopped.

DESCRIPTION OF SYMBOLS 1 Laser printer 3 Paper 27 Toner storage chamber 28 Rotating shaft 29 Agitator 36 Developing cartridge 58 Light transmission window 59 Light transmission window 60 Light emission part 61 Light reception part 62 Optical sensor 75 Electromagnetic clutch 78 Main motor 79 CPU
80 ROM
81 RAM
100 transmission mechanism

Claims (8)

An image forming unit for forming an image on paper;
An accommodating portion for accommodating the developer;
An agitation member provided in the housing unit, driven to rotate, supplies the developer to the image forming unit, and agitates the developer;
A detection unit that detects a remaining amount of the developer, and that detects a rotation period of the stirring member based on a detection result of the remaining amount detection sensor;
A transmission mechanism for switching the rotation speed of the stirring member;
A control unit for controlling the switching operation of the transmission mechanism;
After the control unit controls the switching operation of the speed change mechanism so that the stirring member rotates at a first speed at which the stirring member rotates when the image forming unit forms an image on a sheet, The detection unit after the control unit controls the switching operation of the speed change mechanism so that the stirring member rotates at a first rotation period of the detected stirring member and a second speed slower than the first speed. A comparison determination unit that determines whether or not the second rotation period of the stirring member detected by
An image forming apparatus comprising: an abnormality determining unit that determines that the speed change mechanism is abnormal when the comparison determining unit determines that the first rotation period and the second rotation period coincide with each other. . The image forming apparatus according to claim 1.
When the abnormality determining unit determines that the transmission mechanism is abnormal, and when the first rotation period and the second rotation period are rotation periods according to the first speed, the transmission mechanism is An image forming apparatus comprising an informing unit for informing that there is an abnormality. The image forming apparatus according to claim 2.
The image forming apparatus, wherein the notification unit notifies that the image forming unit can form an image. The image forming apparatus according to claim 2.
The image forming apparatus characterized in that the notification unit notifies that the life of the developer is shortened. The image forming apparatus according to claim 1.
When the abnormality determination unit determines that the transmission mechanism is abnormal, and when the first rotation period and the second rotation period are rotation periods according to the second speed, the transmission mechanism is An image forming apparatus comprising an informing unit for informing that there is an abnormality. The image forming apparatus according to claim 5.
The image forming apparatus is characterized in that the notification unit notifies that the density at which the image forming unit forms an image on a sheet is low. The image forming apparatus according to any one of claims 1 to 6,
The control unit controls the switching operation of the transmission mechanism so that the speed at which the stirring member rotates during the initialization operation is set to the second speed, and the speed at which the stirring member rotates during image formation is set to the first speed. In this way, the image forming apparatus controls the switching operation of the transmission mechanism. The image forming apparatus according to any one of claims 1 to 7,
A driving source for generating a driving force;
A photosensitive drum carrying a developer transferred to the paper;
An exposure device for exposing the photosensitive drum;
A developing roller that supplies developer to the photosensitive drum exposed by the exposure device to develop the photosensitive drum, and obtains a driving force from the driving source to rotate.
The stirring member supplies a developer to the developing roller, rotates by obtaining a driving force from the driving source,
The speed change mechanism is provided in a driving force transmission circuit from the driving source to the developing roller and the stirring member,
The control unit controls the switching operation of the transmission mechanism so that the first speed is achieved when image formation is performed, and the switching operation of the transmission mechanism is performed so that the second speed is achieved when image formation is not performed. An image forming apparatus that controls the image forming apparatus.

Images