JPH07104619A - Image forming device - Google Patents

Abstract

PURPOSE:To accurately detect the exchange time of a photoreceptor drum and a cartridge by detecting the shaved state of an organic photoreceptive layer formed on an image carrier. CONSTITUTION:The organic photoreceptive layer with which the surface of the photoreceptor drum 7 is coated is smooth in the initial stage of use, and reflects much light. However, it becomes rough because of the shaving of the surface as the device is used, and the light radiated from a light emitting element 15a to the organic photoreceptive layer is diffused and does not enter a light receiving element 15b. Namely, as the number of recorded sheets is increased and the organic photoreceptive layer of the drum 7 is shaved, the reflectance of the surface of the drum 7 is decreased, and in the case the organic photoreceptive layer of the drum 7 is shaved by image-forming and the thickness thereof is decreased, what is called 'fogging' is caused on an image. Therefore, a drum life detection signal is outputted by judging the end of the life of the drum 7 when the reflectance of the organic photoreceptive layer is a previously set value and the light receiving 14b detects the effect.

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 for forming an image on a recording medium using an image carrier having an organic photosensitive layer, and more particularly to an image forming apparatus for detecting the life of the image carrier or the cartridge.

[0002]

2. Description of the Related Art An image forming apparatus such as a printer forms a latent image by selectively exposing a uniformly charged photosensitive drum to form a latent image, and the latent image is visualized with a toner. An image is recorded by transferring the image to a recording medium. In such an apparatus, when it is used for a long period of time, the photosensitive drum is scraped off, and so-called fog or the like occurs during image formation.

Therefore, conventionally, as a means for informing the life of the photoconductor drum, an analog counter system has generally been used in which the rotation of the photoconductor drum is decelerated by a plurality of stages of gears to rotate a disk.

Further, in the image forming apparatus, toner must be replenished each time it runs out, but this toner replenishment work is not only troublesome, but it can also become dirty. In addition, maintenance of each member can be performed only by a specialized service person, which often causes inconvenience to the user.

Therefore, the photosensitive drum, the charging device, the developing device, the cleaning unit, and the like are integrally formed into a cartridge so that the user can load the cartridge into the main body of the apparatus to replenish toner and extend the life. It has been put into practical use that the parts of the photoconductor drum that have reached can be replaced and the maintenance is easy. In an image forming apparatus equipped with such a cartridge, it is necessary to replace the cartridge when the toner in the cartridge is used up.

Therefore, conventionally, as a means for notifying the replacement of the cartridge, a method of detecting the amount of the residual toner in the developing device or the amount of the waste toner removed by the cleaning portion by the change of the electrostatic capacity is generally used. ing.

[0007]

However, in the analog counter method, there is a problem that the gear reduction ratio must be increased, the number of parts increases and the cost increases. In addition, this deceleration mechanism must be provided on the cartridge side in the system in which the cartridge is mounted, and there is a problem that the cost of the cartridge itself is increasing.

Further, in the method of detecting the amount of toner in the developing device, for example, when image recording with a small print ratio is performed, the abrasion of the photosensitive drum becomes large after the prescribed standard number of prints has passed. However, there is a problem in that the toner consumption amount is small and the toner amount more than the specified amount remains in the developing device.

The present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an image forming apparatus having a simple structure and capable of accurately detecting the replacement time of a photosensitive drum or a cartridge. It is intended to be provided.

[0010]

A typical constitution according to the present invention for achieving the above object is an image carrier having an organic photoconductor on its surface, and a developing means for forming a toner image on the image carrier. A cleaning means for removing the toner remaining on the image carrier, and a life detecting means for detecting the life of the image carrier by detecting a change in the organic photosensitive layer of the image carrier. Will be a feature.

[0011]

In the above structure, since the change of the organic photosensitive layer formed on the image bearing member is directly detected, the life can be accurately determined.

[0012]

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, and FIG. 2 is a structural explanatory view of a process cartridge. Here, as the order of description, the overall configuration of the image forming apparatus in which the process cartridge is mounted will be described, and then the lifetime detection configuration will be described.

{Overall Configuration} This image forming apparatus A is shown in FIG.
As shown in FIG. 3, a structure based on image information is irradiated from the optical system 1 to form an image of a developer (hereinafter referred to as “toner”) on the photosensitive drum that is an image carrier. Then, in synchronization with the formation of the toner image, the recording medium 2 is transferred from the cassette 3a to the pickup roller 3b and the registration roller pair 3c1, 3c2.
In the image forming portion which is conveyed by the conveying unit 3 including the above, and which is formed into a cartridge as the process cartridge B, the toner image formed on the photosensitive drum is applied with voltage to the transfer roller 4 serving as the transfer unit to thereby form the recording medium 2. And the recording medium 2 is conveyed to the fixing unit 5 by the intermediate discharge roller 3d and the guide plate 3e. 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, a photosensitive drum 7 having an organic photosensitive layer on the surface of a grounded cylindrical aluminum substrate is rotated. The surface thereof is uniformly charged by applying a voltage to a charging roller 8 as a charging means, and the optical image from the optical system 1 is exposed on the photosensitive drum 7 via the exposure unit 9 to form a latent image, The developing means 10 is configured to develop. The developing means 10 feeds the toner in the toner reservoir by means of a toner feeding member 10a, and a fixed magnet.
While rotating the developing sleeve 10c containing 10b,
A toner layer to which a triboelectric charge has been imparted by the developing blade 10d is formed on the surface of the developing sleeve 10c, and the toner is transferred to the photosensitive drum 7 according to the latent image to form a toner image and visualize it. To do. Then, after applying a voltage having a polarity opposite to that of the toner image to the transfer roller 4 to transfer the toner image to the recording medium 2, the cleaning blade 11
The toner remaining on the photoconductor drum 7 is scraped off by a, and the residual toner on the photoconductor drum 7 is removed by the cleaning means 11 which is scooped by the squeeze sheet 11b and collected in the waste toner reservoir 11c. The parts such as the photosensitive drum 7 are the first frame 12
It is housed in a housing 12 in which a and a second frame 12b are combined to form a cartridge, which is removably mounted on a cartridge mounting means provided on the apparatus main body 13.

In the cartridge mounting means, when the opening / closing member 14 is opened around the shaft 14a, a cartridge mounting guide member (not shown) is mounted on the left and right inner side surfaces of the opening / closing member 14, and the left and right guide members are process cartridges. Guide portions for inserting B are provided facing each other. Insert the process cartridge B along this guide,
The process cartridge B is attached to the image forming apparatus A by closing the opening / closing member 14.

{Photosensitive Drum Life Detecting Structure} Next, the photosensitive drum 7 life detecting structure will be described. As shown in FIG. 3, a photo coupler as a drum life detecting means is provided at a longitudinal end portion of the photosensitive drum 7 by a distance d.
There are fifteen. This is a light emitting element such as an LED or a lamp 15
a and a light receiving element 15b such as a phototransistor,
The light emitted from the light emitting element 15a is reflected on the surface of the photoconductor drum 7, and the reflected light is incident on the light receiving element 15b.

The organic photosensitive layer coated on the surface of the photosensitive drum 7 is smooth in the initial stage of use and reflects a large amount of light. However, as it is used, the surface is roughened due to abrasion, and the light emitted from the light emitting element 15a to the organic photosensitive layer is scattered and does not enter the light receiving element 15b.

FIG. 4 is a graph showing changes in the reflectance of the surface of the photosensitive drum with respect to the number of recorded sheets when images are repeatedly formed on a recording medium using the photosensitive drum 7. As shown in this graph, the reflectance of the surface of the photosensitive drum decreases as the number of recorded sheets increases and the organic photosensitive layer of the photosensitive drum 7 is scraped.

The thickness of the organic photosensitive layer of the photosensitive drum 7 is about 20 .mu.m to 30 .mu.m. When the organic photosensitive layer is scraped by image formation and the thickness becomes about 10 .mu.m to 20 .mu.m, so-called "fogging" occurs in the image. Therefore, when the number of recorded sheets reaches T, the reflectance of the organic photosensitive layer reaches a preset value (reflectance immediately before fog occurs) A, and when this is detected by the light receiving element 15b, the photosensitive drum 7 of the photosensitive drum 7 is detected. It is configured to output the drum life detection signal when it is judged to be the life.

When the photocoupler 15 detects the light reflectance on the surface of the photosensitive drum, a green light source is used as the light emitting element 15a, and the distance d shown in FIG. 3 is about 1 mm to 4 m.
It is preferable to set m and the angle θ to about 25 ° to 60 °. Since the photosensitive drum 7 has a peak of sensitivity to light having a wavelength of about 650 nm to 780 nm, it absorbs red light well, while reflecting green light, a large reflection gain can be obtained in the case of a green light source. Is.

Further, the photocoupler 15 is a photosensitive drum 7
It is preferable to arrange so as to irradiate the organic photosensitive layer near the end portion in the longitudinal direction. The reason is as shown in FIG.
The photosensitive drum 7 has an organic photosensitive layer 7b coated on an aluminum substrate 7a, but one end 7b1 of this organic photosensitive layer 7b is the beginning of coating and is thinner than other portions. This is because, when the light reflectance is measured at a thin portion of the photosensitive layer, the lower layer is likely to be affected by the use and the reflection gain can be increased.

The photocoupler 15 may be built in the process cartridge B, but it is preferable that the photocoupler 15 is attached to the apparatus main body 13 so that the surface of the photosensitive drum 7 can be illuminated by mounting the process cartridge B. It is preferable to be provided in. Furthermore, photo coupler 15
It is preferable that the surface of the photosensitive drum 7 is disposed between the cleaning means 11 and the charging roller 8 so that the surface of the photosensitive drum 7 can be irradiated.

[Second Embodiment] In the above-described first embodiment, an example in which the life of the photosensitive drum 7 is detected by the light reflectance of the photosensitive drum 7 has been shown. Is shown in FIG.

FIG. 6 shows a portion of the cleaning means 11. As described above, the waste toner remaining on the surface of the photosensitive drum 7 is scraped off by the blade 11a and is stored in the waste toner reservoir 11c. is there. In this cleaning means 11, a foam material seal 11d made of urethane rubber or the like is attached to the opening end portions (both end portions in the longitudinal direction of the photosensitive drum 7) so that the waste toner does not leak from the waste toner reservoir 11c. This is in close contact with both ends of the photosensitive drum 7 in the longitudinal direction. In this embodiment, the foam seal 11d
In order to have conductivity by mixing a conductive agent with
A power source 16 is connected to the seal 11d to apply a voltage of about 5V.

In the above structure, the photosensitive drum 7 is rotated by image formation, and the organic photosensitive layer on the surface is scraped according to the number of recorded sheets, as shown in FIG. When the thickness of the organic photosensitive layer in the formed portion becomes B or less, fog occurs in the image. At this time, foam material seal
Since the organic photosensitive layer is thin at the end portion of the photosensitive drum 7 with which 11d is in contact, the organic photosensitive layer at that portion is scraped and almost disappeared, as shown in FIG. Therefore, the conductive seal 11d is attached to the aluminum base 7a of the photosensitive drum 7.
Since the base body 7a is grounded, a current flows from the seal 11d to the drum 7, and it can be detected that the photosensitive drum 7 has reached the end of its life.

In the above structure, since only one contact is required to be connected to the cartridge B to detect the life of the drum, the structure is simplified.

In the above description, the foam material seal 11d for preventing the leakage of the waste toner is also used as the conductive member that comes into contact with the photosensitive drum 7.
A member independent of 11d may be configured to contact the end of the photosensitive drum 7.

[Third Embodiment] In the above-described embodiment, only the life of the photosensitive drum 7 is detected. However, in the case of the process cartridge B, if the toner in the toner reservoir runs out, the cartridge B must be replaced. I have to. Also, when the waste toner reservoir 11c of the cleaning means 11 is full of waste toner, it must be replaced.

Therefore, as a structure for detecting the life of the cartridge B, in addition to the detection of the life of the photosensitive drum 7, a means for detecting the remaining amount of toner or the amount of waste toner is provided, and the remaining amount of toner in the developing means 10 is determined. An example in which the life of the cartridge B is detected when the amount of waste toner in the cleaning unit 11 is equal to or less than a certain amount or when the amount of waste toner in the cleaning unit 11 is equal to or more than a certain amount is described.

For example, as a structure for detecting the amount of toner remaining in the developing means 10, as shown in FIG.
An antenna wire 17 formed by stretching a conductive wire parallel to the developing sleeve 10c is attached in the vicinity of, and the remaining amount of toner is detected by detecting the impedance change between the developing sleeve 10c and the antenna wire 17. Development sleeve
Since the toner layer formed on 10c is applied with a bias voltage in which a DC component and an AC component are superposed on the developing sleeve 10c so that the toner layer is developed at a position facing the photosensitive drum 7, the antenna line 17 is It becomes an electrode and a voltage is generated.
Since the electrostatic capacity of the voltage varies depending on the amount of toner interposed between the developing sleeve 10c and the antenna line 17, the voltage changes depending on the amount of toner, as shown in FIG. The remaining toner amount is detected based on this voltage change.

Thus, when the detected voltage becomes a predetermined value or less, the "toner-less" signal is output. In order to prevent malfunction, the cartridge replacement signal is output when the toner non-signal is continuously output for a certain time or when the integrated output time of the toner non-signal becomes more than the certain time. It is preferable to configure.

A toner remaining amount detecting means having the above-mentioned structure,
It is provided with both the life detecting means for the photoconductor drum 7 of the first embodiment or the second embodiment described above, and when the remaining amount of toner is below a certain level from each means, or the photoconductor drum 7 has reached the life. In this case, a signal indicating that the process cartridge B has reached the end of its life may be output and a display prompting replacement of the process cartridge B may be displayed.

In place of the toner remaining amount detecting means in the developing means 10, means for detecting that the waste toner removed by the cleaning means 11 is full in the waste toner reservoir 11c is provided. May be output when the process cartridge B has reached the end of its life, or when the photosensitive drum 7 has reached the end of its life. In this case, whether or not a certain amount of waste toner has been collected in the waste toner reservoir 11cd can be determined by the same configuration as the toner remaining amount detecting configuration using the antenna wire described above.

As the structure for detecting the toner amount, in addition to the structure in which the antenna wire is provided, for example, a piezo type detection element, a system for detecting the presence or absence of toner by the intensity of light, or the like can be used. .

[Other Embodiments] In the above-described embodiments, the process cartridge B is mounted on the image forming apparatus A, and the life of the photosensitive drum 7 is detected. The configuration is not limited to the cartridge system, that is, the image forming apparatus in which the photosensitive drum is directly attached to the apparatus body can be similarly applied.

Further, the process cartridge B according to the present invention described above is not limited to the case of forming a single color image as described above, but a plurality of developing means are provided to form a plurality of color images (for example, 2 colors).
It can also be suitably applied to a cartridge that forms a color image, a three-color image, a full-color image, or the like.

As the developing method, various known developing methods such as a two-component magnetic brush developing method, a cascade developing method, a touchdown developing method and a cloud developing method can be used.

As for the constitution of the charging means, the so-called contact charging method was used in the above-mentioned first embodiment, but a tungsten wire which has been conventionally used as another constitution is provided with a metal shield such as aluminum around three sides, It goes without saying that a configuration may be used in which positive or negative ions generated by applying a high voltage to the tungsten wire are moved to the surface of the photosensitive drum to uniformly charge the surface of the drum.

The charging means may be of a blade type (charging blade), a pad type, a block type, a rod type, a wire type or the like, other than the roller type.

Further, as a method for cleaning the toner remaining on the photosensitive drum, the cleaning means may be constituted by using a blade, a fur brush, a magnetic brush or the like.

The above-mentioned process cartridge is
For example, an electrophotographic photosensitive member as an image carrier and at least one process means are provided. Therefore, as the mode of the process cartridge, in addition to the embodiment described above, for example, the image carrier and the charging means are integrally made into a cartridge, which can be attached to and detached from the apparatus main body. The image carrier and the developing means are integrally formed into a cartridge, which can be attached to and detached from the main body of the apparatus. The image carrier and the cleaning means are integrally made into a cartridge so that it can be attached to and detached from the apparatus main body. Further, there is one in which an image carrier and two or more of the above-mentioned process means are combined into an integrated cartridge, which can be attached to and detached from the apparatus main body.

That is, the above-mentioned process cartridge is one in which the charging means, the developing means or the cleaning means and the electrophotographic photosensitive member are integrally made into a cartridge, and the cartridge can be attached to and detached from the main body of the image forming apparatus. . Further, at least one of the charging means, the developing means, and the cleaning means and the electrophotographic photosensitive member are integrally made into a cartridge so that it can be attached to and detached from the main body of the image forming apparatus. Further, it means that at least the developing means and the electrophotographic photosensitive member are integrally made into a cartridge so as to be attachable to and detachable from the apparatus main body.

Further, although the laser beam printer is exemplified as the image forming apparatus in the above-mentioned embodiments, the present invention is not limited to this, and other image forming apparatus such as an electrophotographic copying machine, a facsimile machine, a word processor, etc. It is also possible to use for.

[0045]

As described above, the present invention makes it possible to accurately determine the life by detecting the scraped state of the organic photosensitive layer formed on the image bearing member.

Further, since a special speed reducing mechanism is not required unlike the conventional case, the structure can be simplified and the cost increase can be suppressed.

Further, by using together with the toner amount detecting means, it becomes possible to make a more accurate judgment of the cartridge life.

[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 an explanatory diagram of a configuration in which the life is detected based on the light reflectance of the photosensitive drum.

FIG. 4 is a graph showing the relationship between the number of recorded sheets and the light reflectance of the photosensitive drum.

FIG. 5 is an explanatory diagram of an organic photosensitive layer applied to a photosensitive drum.

FIG. 6 is an explanatory diagram of a configuration in which a life is detected by passing an electric current through a photosensitive drum.

FIG. 7 is a graph showing the relationship between the number of recorded sheets and the organic photosensitive layer.

FIG. 8 is a graph showing the relationship between the toner amount and the voltage of the antenna wire.

[Explanation of symbols]

A ... Image forming apparatus, B ... Process cartridge, 1 ... Optical system, 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, 5 ... Fixing means, 5a ... Drive roller, 5b ... Heater, 5c ... Fixing Rollers, 6 ... Ejecting section, 7 ... Photosensitive drum, 7a ... Substrate, 7b ... Organic photosensitive layer, 7b1 ... End, 8 ... Charging roller, 9 ... Exposed section, 10 ... Developing means, 10a ... Toner feeding member, 10b ... magnet, 10c ... developing sleeve, 10d ... developing blade, 11 ... cleaning means, 11a ... cleaning blade, 11b ... squeeze sheet, 11c ... waste toner reservoir, 11d ... foam material seal, 12 ... housing, 12a ... first frame, 12b ... second frame body, 13 ... device body, 14 ... opening / closing member, 14a ... shaft, 15 ... photocoupler, 15
a ... light emitting element, 15b ... light receiving element, 16 ... power source, 17 ... antenna wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 15/08 112 114 21/10 6605-2H G03G 21/00 326 (72) Inventor Kazuro Ono Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Norio Hashimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takayasu Yumimochi Shimomaruko, Ota-ku, Tokyo 3-30-2 Canon Inc. (72) Inventor Hiroto Hasegawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (11)

[Claims] 1. An image forming apparatus for rotating an image carrier to form an image on a recording medium, the image carrier having an organic photoconductor on the surface thereof, and a developing unit for forming a toner image on the image carrier. Cleaning means for removing the toner remaining on the image carrier, and life detecting means for detecting the life of the image carrier by detecting changes in the organic photosensitive layer of the image carrier. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the life detecting unit irradiates the organic photosensitive layer with light and detects the life of the image carrier by the reflected light. 3. The life detecting means applies a voltage between a conductive member in contact with the organic photosensitive layer and a base of the image carrier, and detects the life of the image carrier by the amount of electricity. The image forming apparatus according to claim 1, wherein the image forming apparatus is a device. 4. The method according to claim 2 or 3, wherein the life detecting means detects a change in the organic photosensitive layer at an end portion of the image bearing member where the organic photosensitive layer is thin. Image forming device. 5. The image forming apparatus according to claim 1, wherein the life detecting unit compares the detected amount with a reference value, and outputs a replacement signal for the image carrier when the detected amount exceeds the reference value. apparatus. 6. An image forming apparatus for forming an image on a recording medium by mounting a process cartridge, comprising: an image carrier having an organic photosensitive layer; and at least one process unit acting on the image carrier. Mounting means for mounting an image carrier, a life detecting means for detecting a change in the organic photosensitive layer of the image carrier to detect the life of the image carrier, and a toner for detecting the amount of toner in the process cartridge. An image forming apparatus comprising: an amount detecting unit, and a cartridge replacement signal is output according to a detection signal of either the life detecting unit or the toner amount detecting unit. 7. The image forming apparatus according to claim 6, wherein the toner amount detecting means detects the remaining amount of toner in the developing means. 8. The image forming apparatus according to claim 6, wherein the toner amount detecting means detects the amount of waste toner in the cleaning means. 9. The image forming apparatus according to claim 1, wherein the image forming apparatus is an electrophotographic copying machine. 10. The image forming apparatus according to claim 1, wherein the image forming apparatus is a laser beam printer. 11. The image forming apparatus according to claim 1, wherein the image forming apparatus is a facsimile apparatus.