JPH0416865A - Image forming device - Google Patents

Abstract

PURPOSE:To properly replace a process cartridge by sending a signal and making an alarm display prompting the replacement when the amount of developer reaches a specific value where proper image formation is impossible or when specific equipment in the cartridge reaches specific life. CONSTITUTION:The device is provided with a 1st detecting means 1 which sends a signal when the amount of the developer T in a developing means 4 reaches the specific value where proper image formation can not be performed and a 2nd detecting means 12 which sends a signal when specific equipment in the process cartridge 12 reaches specific life. Then the alarm display which prompts the replacement of the process cartridge 10 is made when the 1st or 2nd detecting means 11 or 12 sends the signal first. Consequently, the replacement period of the process cartridge 10 is accurately grasped regardless of how much the developer T is used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer using electrophotography.

(Prior Art) In copying machines and the like, a process cartridge is composed of a photosensitive drum as a carrier and image forming equipment arranged around the photosensitive drum, such as a charging roller, a developing device, a cleaning device, etc. Many of these devices are built into the container and can be integrally attached to and removed from the device body.

This process cartridge is designed so that even if the equipment inside the process cartridge reaches the end of its lifespan, image formation can be continued by a general user by replacing the process cartridge, which simplifies maintenance. The purpose is to achieve this goal.

The following methods are known as methods for notifying the user when to replace the process cartridge.

(1) A method that detects the amount of toner (developer) in the developing device and prompts to replace the process cartridge when the amount falls below a certain value.

(2) Assuming the amount of toner used per sheet of transfer paper (transfer material), if the number of prints on the transfer paper reaches a predetermined amount, the toner in the developing device is insufficient. A method of prompting the replacement of process cartridges according to the number of rotations of the photosensitive drum corresponding to printing.

(Problem to be solved by the invention) However, in method (1), when printing continues with a small amount of toner, there is enough toner in the developing device despite the large number of prints, so the process Although the cartridge is not replaced, there is an inconvenience that the photosensitive drum deteriorates due to rubbing against the cleaning blade of the cleaning device, resulting in one image defect (background fog, density reduction).

This is because the lifespan of the photosensitive drum is set according to the number of prints, which is proportional to the amount of toner.
This is because if you print up to 5 times as much, the photosensitive drum will deteriorate.

In addition, if printing continues with a large amount of toner used (1
) There is no problem with method (2), but even though there is insufficient toner in the developing device, a warning to replace the process cartridge is not issued, resulting in one image defect (self-injection, etc.). There was an inconvenience that it ended up happening.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus in which process cartridges can be replaced appropriately without causing image defects.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an image forming apparatus in which, in addition to an image carrier, a process cartridge having at least a developing means is removably disposed in an apparatus main body. A first detection means that issues a signal when the amount of developer in the device reaches a predetermined amount at which proper image formation is not possible, and a second detection device that issues a signal when a specific device in the process cartridge reaches a predetermined lifespan. and a first means. The present invention is characterized in that a warning display prompting replacement of the process cartridge is displayed at the time when the first signal among the signals from the second detection means is issued.

(Function) The amount of developer in the developing means is detected by the first detecting means, and the life of the equipment in the process cartridge is detected by the second detecting means. Since the process cartridge is prompted to be replaced when the above signal is issued, if an image is formed using a small amount of developer, the second detection means will issue a warning to replace the process cartridge. If an image is formed using a large amount of developer, the first detection means will issue a warning to replace the process cartridge.

Therefore, regardless of the amount of developer used, the time to replace the process cartridge can be accurately determined.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

First, a first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a cross-sectional view showing a state in which a process cartridge 10 is installed in the main body of an image forming apparatus. In the figure, 1 is a photosensitive drum serving as an image carrier that rotates in a fixed direction.
A cleaning device 2 is installed around the photosensitive tram l. - Next, a charging roller 3, a developing device 4, and a transfer roller 5 are provided.

The cleaning device 2 rubs the cleaning plate 2a against the photosensitive drum 1, uses the cleaning blade 2a to scrape off residual toner around the photosensitive drum 1 after transfer, and stores it in the cleaner body 2b to remove the remaining toner from the photosensitive drum 1. 1 cleaning is performed.

The developing device 4 has a container main body 4 a holding toner T as a developer therein, and rotates in a fixed direction, attracts the toner T in the container main body 4 a to its outer circumference and supplies it to the photosensitive tram 1 . The developing sleeve 4b is composed of a doctor blade 4C and the like that regulates the layer thickness of the toner T adsorbed on the outer circumference of the developing sleeve 4b.
When the toner T attracted to the outer periphery of the developing sleeve 4b rotates and is directed toward the photosensitive tram l, a developing bias voltage is applied to the developing sleeve 4b via the bias power supply 6, and the toner T is transferred to the photosensitive tram. It is designed to be supplied to l.

That is, when the photosensitive drum 1 uniformly charged by the secondary charging roller 3 is exposed to only image light from a scanner unit (not shown), an electrostatic latent image is formed on the photosensitive drum 1. As the photosensitive drum 1 rotates, the electrostatic latent image is directed toward a developing sleeve 4b of the developing device 4, and toner T is supplied by the developing sleeve 4b to visualize it as a toner image. The toner image is directed toward the transfer roller 5 as the photosensitive drum I rotates, and is transferred onto the transfer paper P by the transfer roller 5. After the transfer, the photosensitive drum 1 is cleaned of residual toner by the cleaning plate 28 of the cleaning device 2, and is ready for the next image formation.

The transfer paper P is fed toward the photosensitive drum L from a paper feed cassette (not shown), etc., and when the transfer of the toner image is completed, it is sent to a fixing device (not shown), and is then transferred to the fixing device (not shown). The toner image is fixed as a permanent image.

Now, photosensitive drum 1, cleaning device 2. -Next charge a-
La3. The developing device 4 is incorporated into a cartridge container 10a, and is detachably disposed within the I71 device as a process cartridge 10.

When an internal device of the process cartridge 10 reaches the end of its lifespan or the toner T in the developing device 4 is used up, maintenance is facilitated by replacing the entire process cartridge 10. It is something.

5 This image forming apparatus has a process cartridge 1.
In order to replace the toner T at an appropriate time, if the toner T in the developing device 3 decreases to the extent that it becomes difficult to form an appropriate image, a toner detection means 11 that detects this and a photosensitive drum 1 are provided. A device life detection means 12 is provided to detect when the device reaches a predetermined lifespan.

The developing sleeve 4 of the developing device 3 serves as the toner detection means 11.
A toner sensor 20 is provided in the container main body 4a near b, and a comparator 21 is provided on the apparatus main body side, so that when the process cartridge IO is installed in the apparatus main body, the toner sensor 20 and the comparator 21 are electrically connected. Make it.

That is, the toner sensor 20 detects the induced voltage of the developing bias applied to the developing sleeve 20 by the bias power supply 6, and sends this signal to the comparator 21, which compares it with the comparison voltage E. Here, when there is enough toner T in the developing device 4 and the space between the developing sleeve 4B and the toner sensor 20 is filled with toner T, the induced voltage is relatively large, or the toner T decreases, and the developing sleeve 4B and the toner sensor 20 are filled with toner T. When a gap is created between the toner sensor 4b and the toner sensor 20, the induced voltage becomes smaller. Therefore, choosing the comparison voltage E between the above two voltage levels is as follows:
A signal A indicating that there is not enough toner T to form a proper image in the developing device 4 can be taken out from the comparator 21.

The device life detection means 12 includes a gear 30 that decelerates and transmits the rotation of the photosensitive tram 1 to the apparatus main body side, a cam 31 to which rotational force is transmitted from the gear 30, and a cam 31 that rotates until a predetermined position. When the photosensitive tram l is rotated to its lifetime rotation speed N, the cam 31 rotates a predetermined amount via the gear 30, and the microswitch 32 is pressed and turned on. .

It is possible to take out a signal B indicating that the photosensitive tram l has reached the end of its useful life.

Then, the signals A and B are input to a controller (not shown), and when the first signal A or B is input, a warning message indicating that the process cartridge IO should be replaced is displayed on the panel of the main body of the apparatus. It has become so.

1. For example, the developer 4 is filled with enough toner T to process 4,000 sheets of transfer paper P of a predetermined size at a printing rate of 5%, and the photosensitive tram 1 rotates the number of rotations N during its lifetime. Assuming that 8,000 sheets of transfer paper P are processed, if the printing rate is greater than 5%, the toner T will be 4.00 times more than the transfer paper P.
(Although it is consumed before one sheet is processed, at this point, the photosensitive tram l has not yet reached the end of its lifespan, so only the signal A from the toner detection means 11 is transmitted to the controller, and a replacement alarm for the process cartridge lO is issued. is displayed.

Furthermore, if the printing rate is less than 5%, for example 1%, the toner T in the developing device 4 can perform image processing on 20,000 sheets of transfer paper P. When l has processed 8,000 sheets, the device life detection means 12
Only the signal B from the controller is transmitted to the controller, and a replacement alarm for the process cartridge 10 is displayed.

As described above, the toner detection means 11 and the device life detection means 1
Since the process cartridge IO is replaced according to the first signal A or B of the signals A and B of 2, the process cartridge 1O is always replaced under appropriate conditions regardless of the printing progress on the transfer paper P. 1O can be replaced without causing any image defects.

Here, the lifespan of the photosensitive tram l has been explained as the device lifespan, but there are cases where the lifespan of the cleaning blade 2a of the cleaning device 2 or the developing sleeve 4b of the developing device 4 is shorter than that of the photosensitive drum l. That is, the cleaning plate 2a may be worn out as the photosensitive tram 1 rotates before the photosensitive tram 1 reaches its lifetime rotation speed, and streaks due to poor cleaning may appear on the image, and the developing sleeve 4b may also wear out. As it rotates, the contact point of the power supply section of the developing bias may wear out, resulting in poor contact and cracks on the image.

In such cases, the photosensitive tram l for the life of these equipment
The signal B of the equipment life detection means 12 may be emitted depending on the rotational speed N.

Further, instead of the rotation speed of the photosensitive drum l, the number of processed transfer sheets P (number of printed sheets) is electrically detected, and the rotation of the photosensitive drum l is calculated backward from this value.

The number of rotations of the photosensitive tram l may also be calculated.

Next, a second embodiment of the present invention will be described with reference to FIG. Components having the same functions as those in the first embodiment are designated by the same reference numerals, and their explanations will be omitted.

In this embodiment, a surface potential sensor 40 or the like is provided as the device life detecting means 12, and the life of the photosensitive tram 1 is estimated by measuring the surface potential of the photosensitive tram 1 instead of the number of revolutions of the photosensitive tram 1. It is. Generally, the degree of deterioration of the photosensitive tram 1 depends on, for example, the temperature of the atmosphere in which it is used, so its lifetime rotational speed N is determined by the most severe atmospheric conditions. Therefore, under normal usage conditions, even if the photosensitive tram 1 or N times is rotated, there is a possibility that the photosensitive tram 1 may still be usable.

Therefore, in this embodiment, the surface potential of the photosensitive tram 1 is directly measured by the surface potential sensor 40, and this potential is compared with the reference potential E11 by the comparator 41, so that the surface potential of the 5th photosensitive tram 1 reaches the reference potential E2. When this happens, the comparator 41 outputs signal B.

Here, to detect the amount of toner in the developing device 4, a toner detecting means 11 similar to that of the first embodiment is provided, and a signal A from the toner detecting means 11 is used.

Among the signals B from the device life detection means 12, the earliest signal A or B is used to display a process cartridge 10 replacement alarm on the panel.

Therefore, in this embodiment, the same effects as in the first embodiment can be obtained.

Note that the surface potential sensor 40 is attached to the process cartridge 10.
It may be attached to the main body of the device, or from a cost standpoint, it is better to provide it on the main body side of the device.

Next, a third embodiment of the present invention will be described with reference to FIG. Components having the same functions as those in the first embodiment are designated by the same reference numerals, and their explanations will be omitted.

This embodiment relates to a case where the life of the primary charger roller 3 is shorter than the life of the photosensitive drum 1 etc., and a voltage sensor 50 etc. for the primary charging roller 3 is provided as the device life detection means 12.

Since the primary charging roller 3 has the property of increasing its resistance as it is used, a constant current voltage V to this secondary charging roller 3 is applied.
, 7 tends to gradually increase. When the resistance value of the -order charging roller 3 reaches a predetermined value, a charging failure occurs, and the -order charging roller 3 reaches the end of its life.

Therefore, the output voltage of the constant current power supply 7 is detected by the voltage sensor 50 disposed on the main body side of the device, and this is detected by the comparator 5.
1 is compared with a reference voltage E, and if this value becomes larger than the reference voltage E3, the comparator 51 generates a signal B.

In this embodiment as well, the toner detection means 11 is the same as that in the first embodiment, and among the signal A from the toner detection means 11 and the signal B from the one-device life detection means 12,
Process cartridge lO by the earliest signal A or B
A replacement warning is now displayed on the panel.

Therefore, in this embodiment as well, it is possible to obtain the same effects as in the first embodiment.

Next, a fourth embodiment of the present invention will be described with reference to FIG. Components having the same functions as those in the first embodiment are designated by the same reference numerals, and their explanations will be omitted.

In this embodiment, the lifespan of the photosensitive drum l is estimated based on the amount of toner T that unnecessarily adheres to the photosensitive drum l. -60 etc. is provided.

When performing reversal development using the developing device 4, the photosensitive tram l
When the photosensitive drum 1 deteriorates, its surface potential decreases and the toner T adheres to the surface of the photosensitive drum 1. Taking advantage of this phenomenon, light from the light emitting section 60a is applied to the non-image area of the photosensitive drum 1. The reflected light is received by the light receiving section 60b, and the output from the light receiving section 60b is inputted to the comparator 61 and compared with the reference voltage E4.

Since the surface of the photosensitive drum 1 is clean in the non-image area when it is new, the reflected light from the photosensitive drum 1 has sufficient intensity, and the output from the light receiving section 60b is higher than the reference voltage E4 or When the tram 1 deteriorates, toner adheres to the non-image area and the intensity of the reflected light of the tram 1 weakens, so that the output from the light receiving section 60b falls below the reference voltage E4. Therefore, in this case, the signal B may be output from the comparator 61.

1. Also in this embodiment, the toner detection means 11 is the same as that according to the first embodiment, and the toner detection means 11 is provided at 8.
Out of the signal A from the 411 device life detection means 12 and the signal B from the 411 device life detection means 12, the earliest signal A or B causes a process cartridge IO replacement alarm to be displayed on the panel.

Therefore, in this embodiment as well, it is possible to obtain the same effects as in the first embodiment. The optical sensor 60 may be attached to the process cartridge 1o, but from a cost standpoint, it is better to provide it on the apparatus main body side.

As described above, in the first to fourth embodiments, the method using the toner sensor 20 was adopted as the method of detecting the amount of toner, but it is not necessary to be limited to this.
Of course, a magnetic permeability detection method, a detection method using a rainbow sensor, etc. may also be used. In addition, the signal A on the device main body side
, B's warning is not limited to just the display; after that,
The image forming operation may also be disabled. This measure is particularly effective when the process cartridge 10 is used beyond its lifespan and there is a risk that parts such as gears on the main body of the apparatus may be damaged.

(Effects of the Invention) As is clear from the above description, according to the present invention, the time to replace the process cartridge is detected by the first and second detection means from two points: the remaining amount of developer and the lifespan of the device. Since the process cartridge is replaced based on the first signal from the first and second detection means, it is possible to accurately determine when to replace the process cartridge regardless of the amount of developer used. This means that image defects will not occur when using this process cartridge.

[Brief explanation of drawings]

FIG. 1 is a sectional view around the process cartridge of an image forming apparatus according to the first embodiment, FIG. 2 is a sectional view around the process cartridge of the image forming apparatus according to the second embodiment, and FIG. 3 is a sectional view around the process cartridge of the image forming apparatus according to the second embodiment. FIG. 2 is a cross-sectional view of the vicinity of a process cartridge of the image forming apparatus. FIG. 4 is a sectional view of the vicinity of a process cartridge of an image forming apparatus according to a fourth embodiment. 1--Photosensitive drum (image carrier), 4--Developing device (developing means), 10-- Process cartridge. 11-... Toner detection means (first detection means), 12.
... Equipment life detection means (second detection means), T... Toner (developer). Patent applicant Canon Co., Ltd.

Claims (5)

[Claims] (1) In an image forming apparatus in which a process cartridge having at least a developing means in addition to an image carrier is removably disposed within the apparatus main body, the amount of developer in the developing means reaches a predetermined amount that does not allow proper image formation. The first signal that emits a signal when it reaches
and a second detection means that emits a signal when a specific device in the process cartridge reaches the end of a predetermined lifespan, and the first one of the signals from the first and second detection means is emitted. An image forming apparatus characterized in that a warning display prompting replacement of a process cartridge is displayed when the process cartridge is replaced. (2) The specific device in the process cartridge is an image carrier, a cleaning device, or a developing device, and the second detection device is a rotation speed detection device of the image carrier, a device for detecting the number of images formed on a transfer material, or the like. The image forming apparatus according to claim 1, characterized in that: (3) The image forming apparatus according to claim 1, wherein the specific device in the process cartridge is an image carrier, and the second detection means is a surface potential sensor of the image carrier. (4) The image forming apparatus according to claim 1, wherein the specific device in the process cartridge is a charging roller, and the second detection means is a voltage detector applied to the charging roller. (5) The image forming apparatus according to claim 1, wherein the specific device in the process cartridge is an image carrier, and the second detection means is a photodetector for the image carrier.