JPH07295387A - Image forming device - Google Patents

Abstract

PURPOSE:To detect a process cartridge if it is in the normal attachment state by detecting the rotation of an image carrier or a transfer member. CONSTITUTION:In the image forming device to which the process cartridge can be attached/detached and forming an image on a recording medium, when the cartridge is normally attached, a drum gear 17 is engaged with a driving gear 18 and rotated in accordance with the start of an image forming action. At this time, a reflecting member 22 on the side surface of the drum gear 17 is rotated also so that the reflected light quantity is periodically changed when light from a photocoupler 23 is reflected on the reflecting member 22. On the other hand, when the cartridge is not normally attached, the drum gear 17 and the driving gear 18 are not engaged with each other and rotational force is not transmitted to the drum gear 17 even if the driving gear 18 is rotated by the image forming action. Therefore, even if the light emitted from the photocoupler 23 is reflected on the side surface of the drum gear 17, the reflected light quantity is not changed. Thus, the normal attachment of the cartridge can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus capable of detecting the mounting state of a process cartridge.

[0002]

2. Description of the Related Art In an image forming apparatus such as a printer, a latent image is formed by selectively exposing an image carrier uniformly charged by a charger, and the latent image is developed by a developer by a developer. At the same time as forming an image, the image formed by the developer is transferred to a recording medium to record an image. In such an apparatus, maintenance of each member is performed by a professional service person, which may be inconvenient for the user.

Therefore, the image carrier, the charging device, the developing device,
By integrating the cleaning unit and the like into an integrated structure into a cartridge, the user can replenish the developer and replace the parts of the image carrier that have reached the end of life by loading the cartridge into the main body of the apparatus, facilitating maintenance. What has been done has been put to practical use.

In such an apparatus for forming an image by mounting the process cartridge, a cartridge mounting / non-mounting detecting mechanism is provided. The detection method is roughly classified into two types, one is a method in which a process cartridge is mounted and the position of a member provided in the image forming apparatus is physically moved to be detected, and the other one is detected. Is a method in which an electric sensor is provided to measure the process cartridge and the output value is detected.

In the former case, a movable lever moves inside the main body of the image forming apparatus. At this time, the presence or absence of the cartridge is detected by detecting the movement of the lever with a photo sensor or a micro switch. The latter is to detect the remaining amount of toner, and in a general image forming apparatus, when the amount of light transmission that changes depending on the amount of toner in the developing device in the cartridge and the toner contains a magnetic substance, , A sensor for measuring the magnetic force is provided. Then, when the remaining toner amount is detected and a signal of a level without toner is obtained, it is determined that there is no toner or no cartridge.

[0006]

However, in the above-mentioned conventional method, the presence or absence of the process cartridge can be detected, but it cannot be determined whether or not the process cartridge is mounted at a predetermined position. It was

That is, in order for the process cartridge to operate, the drum gear integrally attached to the photosensitive drum, which is the image bearing member, and the drive gear on the side of the apparatus main body for driving the same mesh with each other, and the drive on the main body side Need to be transferred to the cartridge. Further, in order to carry out the charging and developing processes, it is necessary that the electric contacts of the cartridge and the image forming apparatus main body are in contact with each other.

Regarding the meshing of the gears, since the module of the gear used in a general image forming apparatus is about 1 mm, it is possible to mesh when the process cartridge is displaced by about 1 mm from a predetermined position. As a result, the photoconductor drum cannot be rotated even if the gear on the apparatus body side rotates. Further, regarding the electric contact, the electric contact is configured to surely make contact even if the electric contact varies to some extent by the spring member, but since the stroke is generally about 2 to 3 mm, For example, if the process cartridge deviates from the mounting position by 4 mm or more, no current is supplied to the cartridge, and the rotational force is not transmitted to the photosensitive drum due to the reason described above. Therefore, the process cartridge must be accurately mounted in place.

However, in the conventional cartridge presence / absence detection configuration, even when the cartridge is not accurately mounted at the predetermined position, the apparatus body side may determine that the cartridge is present, and the image forming operation is started. However, if the cartridge is not mounted correctly, the recording medium will be jammed even if it is transported.

Further, since the image forming process is performed with the photosensitive drum stopped, a transfer bias voltage is applied at the image transfer position of the photosensitive drum, and this portion is charged with electric charge. Therefore, even if the process cartridge is subsequently reattached to the normal position and image formation is performed, the photosensitive drum partially has a large electric charge, and this local electric charge is a known primary charging process 1.
If it is not removed, the abnormal image is formed. This abnormal image appears as a black band at every rotation cycle of the photoconductor drum, and if it is from 10 sheets to a long one, that state continues for about 50 sheets. Moreover, since there is no means for detecting abnormal charging of the photosensitive drum or output of a dirty image, it is not recognized that the abnormal image has been output until the user of the apparatus confirms the image. There was a problem.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an image forming apparatus capable of detecting that a process cartridge is properly mounted.

[0012]

A typical configuration according to the present invention for achieving the above object is such that a process cartridge is attachable / detachable and at least rotatable in an image forming apparatus for forming an image on a recording medium. Mounting means for mounting a process cartridge having a different image carrier, a transfer member for transferring an image formed on the image carrier to a recording medium, and a transporting means for transporting the recording medium, Rotation detecting means for detecting the rotation of the image carrier is provided.

[0013]

In the above structure, when the process cartridge is mounted, it is not mounted in the normal position, and image formation is executed unless, for example, the gear that transmits the driving force to the image carrier and the drive gear of the main body are meshed. However, the image carrier does not rotate. At this time, the rotation detecting means of the image carrier detects this, so that it can be detected that the process cartridge is not mounted at the normal position.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, as an embodiment of the present invention, an image forming apparatus in which a process cartridge can be mounted will be specifically described with reference to the drawings.

[First Embodiment] FIG. 1 is a structural explanatory view of an image forming apparatus in which a process cartridge is mounted, FIG. 2 is a structural explanatory view of a process cartridge, and FIG. 3 is an explanatory view of a mounting structure of a process cartridge. Is. Here, as an order of description, the overall configuration of the image forming apparatus in which the process cartridge is mounted will be described, and then the configuration of the rotation detection unit of the image carrier will be described.

{Overall Configuration} This image forming apparatus A is shown in FIG.
As shown in, the optical means 1 irradiates an optical image based on image information to form a toner image on the photosensitive drum, which is an image carrier. This optical means 1 rotates and scans the light of a laser diode 1a, which emits a laser beam according to image information, by a polygon mirror 1c rotated by a scanner motor 1b, and scans the laser beam with a lens 1d and a reflection mirror 1e.
It irradiates the photosensitive drum by irradiating the photosensitive drum.

In synchronism with the formation of the toner image, the recording medium 2 is conveyed from the cassette 3a by the conveying means 3 including the pickup roller 3b and the pair of registration rollers 3c1 and 3c2, and is made into a process cartridge B as a cartridge. In the image forming section, the toner image formed on the photosensitive drum is transferred to the recording medium 2 by applying a voltage to the transfer roller 4 as a transfer means, and the recording medium 2 is fixed by the intermediate discharge roller 3d and the guide plate 3e. Transport to means 5. The fixing means 5 comprises a driving roller 5a and a fixing roller 5c having a heater 5b built therein, and applies heat and pressure to the recording medium 2 passing therethrough to fix the transferred toner image. Then, the recording medium 2 is conveyed by the discharge roller pair 3f, and is discharged to the discharge portion 6 through the reverse transport path.

On the other hand, in the process cartridge B forming the image forming portion, as shown in FIGS. 1 and 2, the photosensitive drum 7 having a photosensitive layer is rotated, and the surface thereof is transferred to a charging roller 8 as a charging means. Is uniformly charged by the application of the voltage, and the optical image from the optical means 1 is exposed to the photosensitive drum 7 through the exposure section 9 to form a latent image, and the latent image is developed by the developing means 10. There is. The developing means 10 sends out the toner in the toner reservoir by the toner feeding member 10a,
While rotating the developing roller 10c having the fixed magnet 10b built therein, a toner layer to which a triboelectric charge is applied by the developing blade 10d is formed on the surface of the developing roller 10c, and the toner is transferred to the photosensitive drum 7 according to the latent image. By transferring, a toner image is formed and visualized. Then, after a voltage having a polarity opposite to that of the toner image is applied to the transfer roller 4 to transfer the toner image onto the recording medium 2, the cleaning blade 11a scrapes off the toner remaining on the photosensitive drum 7, and the scooping sheet 11b scoops it. The residual toner on the photoconductor drum 7 is removed by the cleaning means 11 which collects and collects it in the waste toner reservoir 11c. Each component such as the photosensitive drum 7 is a first frame member.
The cartridge 12a and the second frame 12b are housed in a housing 12 that is combined to form a cartridge, and the cartridge 12 is detachably mounted on a cartridge mounting means provided on the apparatus main body 13.

When the opening / closing member 14 is opened about the shaft 14a in the cartridge mounting means, as shown in FIGS. 3 (a) and 3 (b), the cartridge mounting guide member G1 is provided on the left and right inner side surfaces of the opening / closing member 14. It is attached and this left and right guide member G1
Guide part for inserting the process cartridge B into
G2 is provided opposite. The process cartridge B is inserted into the image forming apparatus A by inserting the process cartridge B along the guide portion G2 and closing the opening / closing member 14.

At this time, as shown in FIG. 1, the contact 16 on the apparatus main body side urged by the spring 15 comes into contact with the contact of the process cartridge B to be electrically connected, and the bias voltage to the charging roller 8 and the like. Can be applied.

{Structure of Photosensitive Drum Rotation Detection Means} In this embodiment, by detecting the rotation of the photosensitive drum 7 it is determined whether the process cartridge B is properly mounted at a predetermined position of the image forming apparatus A. I am trying to do it.

Next, the structure of the rotation detecting means for the photosensitive drum 7 will be described with reference to FIG. A drum gear 17 is fixed to one end of the photosensitive drum 7 in the longitudinal direction, and when the process cartridge B is mounted at a normal position, the drum gear 17 meshes with a drive gear 18 rotated by a main motor provided in the apparatus main body 13. The driving force is transmitted to the photosensitive drum 7. A gear 19 is also fixed to the other end of the photosensitive drum 7 in the longitudinal direction, and the gear 19 meshes with a transfer gear 20 fixed to the rotation shaft of the transfer roller 4, and the rotational force is transmitted to the transfer roller 4. It has become so. The transfer roller 4 is biased toward the photosensitive drum 7 by a spring 21.

A reflecting member 22 is attached to the side surface of the drum gear 17 as shown in FIG.
On the 13 side, a photocoupler 23 including a light emitting element and a light receiving element is provided at a position facing the side surface of the drum gear 17.
The light from this photo coupler 23 is the cartridge housing.
The side surface of the gear is irradiated with the light through a hole 24 provided in 12, and the reflected light is received by a light receiving element. The rotation state of the photosensitive drum 7 is detected based on the change in the reflected light amount.

In the above structure, the case where the process cartridge B is normally mounted and the case where it is not normally mounted will be described.

First, when the process cartridge B is properly mounted, the drum gear 17 and the drive gear 18 mesh with each other, and the drum gear 17 rotates by the start of the image forming operation. At this time, the reflecting member 22 on the side of the gear also rotates,
When the light from the photocoupler 23 is reflected by the reflecting member 22, the amount of reflected light is large, and when it is reflected by other portions, the amount of reflected light is smaller. That is, the amount of reflected light changes regularly.

On the other hand, when the process cartridge B is not properly mounted, the drum gear 17 and the drive gear 18 do not mesh with each other. Therefore, the drive gear is changed by the image forming operation.
Even if 18 rotates, the rotational force is not transmitted to the drum gear 17,
The photoconductor drum 7 does not rotate. Therefore, the photo coupler 23
Even if the light emitted from is reflected on the side surface of the drum gear, the amount of reflected light does not change.

As described above, it is possible to determine whether or not the photosensitive drum 7 is rotating, based on the variation in the amount of reflected light, and thus it is possible to detect whether or not the process cartridge B is normally mounted. When it is determined that the image forming apparatus has not been normally attached, the image forming operation is stopped so that the occurrence of an abnormal image can be prevented.

Regarding the connection of the electrical contacts, the gear module is generally designed to have a length of about 1 mm, and even if the process cartridge B is lifted from the normal position by about 2 mm, the drive transmission to the photosensitive drum 7 is not performed. . At this time, the electric contact 16 can utilize the stroke of the contact spring 15, which generally has a margin of about 5 mm. Therefore, if the photoconductor drum 7 is rotating normally,
It can be determined that the electrical contact 16 is also normally connected.

[Second Embodiment] In the above-described first embodiment, a reflecting member 22 is attached to the side surface of the drum gear 17, and the rotation of the photosensitive drum 7 is detected by the change in the amount of light reflected by the reflecting member 22. The second embodiment of the rotation detection configuration of the photoconductor drum 7 will be described with reference to FIG.
The members having the same functions as those of the first embodiment described above are designated by the same reference numerals, and the duplicated description will be omitted.

In this embodiment, the light from the optical means 1 is used to detect the rotation of the photosensitive drum 7. That is, as shown in FIG. 5, a reflecting member 25 is provided outside the image forming region at one longitudinal end of the photosensitive drum 7, and the reflecting member 25 is provided by the polygon mirror 1c during image exposure. It is configured so that light is always applied to the existing area. Then, the light reflected by the reflecting member 25 is configured to be received by the light receiving sensor 26.

In this way, when the process cartridge B is mounted in the normal position and the photosensitive drum 7 rotates,
The reflecting member 25 is periodically irradiated with the laser light, and the reflected light is received by the light receiving sensor 26. On the other hand, if the process cartridge B is not mounted in the normal position, the photosensitive drum 7 does not rotate and the laser light is not emitted to the reflecting member 25. Therefore, similarly to the first embodiment described above, the rotation of the photosensitive drum 7 can be detected by the fluctuation of the reflected light amount received by the light receiving sensor 26, and the mounting state of the process cartridge B can be detected.

[Third Embodiment] FIG. 6 shows another embodiment of the rotation detecting structure of the photosensitive drum 7. In the above-described embodiment, the drive gear 18 for driving the photosensitive drum 7 receives a driving force from the main motor 27 provided in the main body 13 of the apparatus. It is transmitted to each member such as the means 3. However, the load torque of the image forming apparatus accounts for a large proportion of the load torque of the fixing unit 5 and the process cartridge B. Therefore, as shown in FIG. 6, a torque detection circuit 28 for detecting the load torque of the main motor 27 is provided, and the rotation state of the photosensitive drum 7 can be detected by detecting the torque value.

That is, when the process cartridge B is mounted in the normal position and the rotational force is transmitted to the photosensitive drum 7,
When the load torque (motor drive current) of the main motor 27 increases, the process cartridge B is not transmitted to the normal position, and the rotational force is not transmitted to the photoconductor drum 7, the load torque (motor drive current) of the main motor 27 is Get smaller. Accordingly, the torque detection circuit 28 detects the variation of the torque value (current value), and if the load torque value is equal to or less than the predetermined value even if the image forming operation is started, the CPU 29 controls to stop the image formation. With the configuration, it is possible to obtain the same effect as that of the first embodiment described above.

[Fourth Embodiment] In the first to third embodiments described above, an example in which the mounting state of the process cartridge B is determined by detecting the rotational state of the photosensitive drum 7 has been described. An example of determining the mounting state of the process cartridge B by detecting the rotation state of the transfer roller 4 will be described as a fourth embodiment with reference to FIG. 7.
It should be noted that members having the same functions as those in the first embodiment are designated by the same reference numerals and duplicate description is omitted.

In this embodiment, the reflecting member 22 and the photocoupler 23 of the first embodiment are provided for the transfer roller 4. That is, a reflecting member 22 is attached to the side surface of the transfer gear 20, and a photocoupler 23 having a light emitting element and a light receiving element capable of irradiating the reflecting member 22 with light and receiving the reflected light is attached to a frame 30 supporting the transfer roller 4. It is a thing.

In this way, the rotation state of the transfer roller 4 can be detected in the same manner as the operation described in the first embodiment. The transfer roller 4 is connected to the photosensitive drum 7.
Since the driving force is transmitted from the process cartridge B, the process cartridge B is not mounted at the normal position, and thus the transfer roller 4 does not rotate when the photosensitive drum 7 does not rotate. Therefore, by detecting the rotation state of the transfer roller 4, it is possible to detect whether or not the process cartridge B is mounted in the normal position.

[Fifth Embodiment] FIG. 8 shows another example of determining the mounting state of the process cartridge B by detecting the rotational state of the transfer roller 4. Also in this case, members having the same functions as those in the above-described embodiment are designated by the same reference numerals, and a duplicate description will be omitted.

In this embodiment, a helical gear is used as the transfer gear 20, and the photosensitive drum 7 that transmits the driving force to the gear is used.
The gear 19 attached to is also using a helical gear. The rotary shaft 4a of the transfer roller 4 is movable in the axial direction, and is urged by the thrust spring 31 in the direction of arrow c. A block 30a of the frame 30 stands upright on the right end side where the rotating shaft 4a is biased, and a touch sensor 32 is provided on the other end side.

In the above construction, when the process cartridge B is not mounted, or when the process cartridge B is not mounted in the normal position, the transfer roller shaft 4a is biased by the spring 31 in the direction of arrow c,
It does not contact the touch sensor 32. On the other hand, when the process cartridge B is mounted at the normal position and the rotational force is transmitted to the transfer roller 4, the transfer roller 4 generates a thrust force in the direction opposite to the arrow c by the action of the helical gears 19 and 20. ,
The transfer roller 4 moves against the bias of the spring 31. Then, the end of the shaft 4a pushes the touch sensor 32. Therefore, whether or not the transfer roller 4 is rotating is detected, and as a result, it can be determined whether or not the process cartridge B is normally mounted.

[Other Embodiments] The image carrier used in the above-mentioned embodiments is not limited to the above-mentioned photosensitive drum, but includes, for example, the following. First, a photoconductor is used as the photoconductor, and examples of the photoconductor include amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, and organic photoconductor (OPC). Further, as the shape for mounting the photoconductor, for example, a drum shape,
It includes a rotating body such as a belt and a sheet. Generally, a drum-shaped or belt-shaped one is used. For example, in the case of a drum type photoconductor, a photoconductor is vapor-deposited or coated on a cylinder of aluminum alloy or the like. Is.

Although a laser beam printer is illustrated as an image forming apparatus in the above-described embodiments, the present invention is not limited to this, and other image forming apparatuses such as an electrophotographic copying machine, a facsimile machine, a word processor, etc. can be used. It is also possible to use for.

[0042]

As described above, according to the present invention, since the rotation of the image carrier or the transfer member is detected, it can be surely determined whether or not the process cartridge is mounted at the normal position. Therefore, it is possible to prevent the image forming operation from being performed while the process cartridge is imperfectly mounted, and it is possible to prevent, for example, a jam or the occurrence of an abnormal image.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view of an image forming apparatus equipped with a process cartridge according to an exemplary embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a process cartridge.

FIG. 3 is a structural explanatory view of a mounting unit of a process cartridge.

FIG. 4 is an explanatory diagram of a rotation detection configuration of a photosensitive drum according to the first exemplary embodiment.

FIG. 5 is an explanatory diagram of a rotation detection configuration of a photosensitive drum according to a second embodiment.

FIG. 6 is an explanatory diagram of a rotation detection configuration of a photosensitive drum according to a third exemplary embodiment.

FIG. 7 is an explanatory diagram of a rotation detection configuration of a transfer roller according to a fourth embodiment.

FIG. 8 is an explanatory diagram of a rotation detection configuration of a transfer roller according to a fifth embodiment.

[Explanation of symbols]

A ... Image forming apparatus, B ... Process cartridge, 1 ... Optical means, 1a ... Laser diode, 1b ... Scanner motor, 1c ... Polygon mirror, 1d ... Lens, 1e ... Reflection mirror, 2 ... Recording medium, 3 ... Conveying means, 3a ... Cassette, 3b ... Pickup roller, 3c1, 3c2 ... Registration roller, 3d ... Intermediate transport roller, 3e ... Guide plate, 3f
... Ejection roller, 4 ... Transfer roller, 4a ... Rotating shaft, 5 ... Fixing means, 5a ... Drive roller, 5b ... Heater, 5c ... Fixing roller, 6 ... Ejection section, 7 ... Photoconductor drum, 8 ... Charging roller, 9 Exposed portion, 10 developing means, 10a toner feeding member, 10b magnet, 10c developing roller, 10d developing blade, 11 cleaning means, 11a cleaning blade, 11b squi sheet, 11c waste toner reservoir, 12 ... housing, 12a ... first frame, 12b ... second frame, 13 ... apparatus main body, 14 ... opening / closing member, 14a ... shaft, 15 ... spring, 16 ... contact,
17 ... Drum gear, 18 ... Drive gear, 19, 20 ... Gear, 21 ... Spring, 22 ... Reflecting member, 23 ... Photo coupler, 24 ... Hole, 25 ... Reflecting member, 26 ... Light receiving sensor, 27 ... Main motor, 28 ... Torque detection circuit, 29 ... CPU, 30 ... Frame, 30a ... Block, 31 ... Thrust spring, 32 ... Touch sensor

Claims (7)

[Claims] 1. An image forming apparatus for forming an image on a recording medium, wherein a process cartridge is attachable / detachable, and mounting means for mounting a process cartridge having at least a rotatable image carrier, said image carrier. A transfer member for transferring the image formed on the recording medium to a recording medium, a conveying unit for conveying the recording medium, and a rotation detecting unit for detecting the rotation of the image carrier. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the rotation detecting unit irradiates the image bearing member with light and detects the amount of reflected light by changing the amount of reflected light. 3. The image forming apparatus according to claim 2, wherein the image bearing member is irradiated with light from an optical unit for exposing the image bearing member. 4. The image forming apparatus according to claim 1, wherein the rotation detecting means detects the load torque for driving the image bearing member. 5. An image forming apparatus for forming an image on a recording medium, wherein a process cartridge is attachable / detachable, and mounting means for mounting a process cartridge having at least an image carrier, and rotation of the image carrier. A transfer member that rotates and transfers the image formed on the image carrier to a recording medium, a transport unit that transports the recording medium, and a rotation detection unit that detects the rotation of the transfer member. An image forming apparatus comprising: 6. The image forming apparatus according to claim 5, wherein the rotation detecting unit irradiates the transfer member with light and detects the change by the change in the reflected light amount. 7. The image forming apparatus according to claim 5, wherein the rotation detecting means detects a change in the position of the transfer member.