JPH04139471A - Toner residual detecting device - Google Patents

Abstract

PURPOSE:To detect the exchanging time of a developing device by comparing a signal value from a storage means with a signal value about toner residual in the developing device from a detection means through a comparison means. CONSTITUTION:When a new process cartridge 8 having different kind of toner is loaded in the device main body of an image forming device, an ID number is inputted and stored in a 2nd memory 25 from a microcomputer 30. At a stage where an image is formed by the cartridge 8, an initial current value which flows in an electrode 21 for detection from a developing roller 3b is converted into a voltage value through a conversion means 22 and stored in a storage area corresponding to the ID number in a 1st memory 24. The value of a ratio between a voltage value based on the initial current value and the voltage value transmitted through the electrode 21 and the means 22 from moment to moment is compared and examined by a comparison and decision means 23. When the value of the ratio attains a specified value, a warning signal is outputted to an exchanging display means 26. Thus, a developing device 3 is surely exchanged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a remaining toner amount detection device that detects when to replace a developing device of an image forming apparatus such as a copying machine or a laser beam printer.

(Prior Art) In an image forming apparatus such as a copying machine using electrophotographic technology, the toner (developer) in the developing device will be used up over a long period of time, so the toner (developer) in the developing device will be used up. It is necessary to replace the developing device with a new one.

For example, if a developing device is built into a process cartridge, the process cartridge will be replaced when the remaining amount of toner in the developing device falls below a predetermined amount. There is one as shown in Japanese Patent Application Laid-Open No. 63-210871.

This method treats the decrease due to toner consumption in the toner storage section of the developing device as a decrease in the capacitance inside the toner storage section, converts the capacitance value into voltage or time using an exchange circuit, and converts the capacitance value into voltage or time using an exchange circuit. If the amount falls below the reference value, it is assumed that the remaining amount of toner in the developing device is insufficient, and an indication to replace the process cartridge is not displayed.

(Problem to be Solved by the Invention) However, in the conventional example, the amount of toner remaining in the toner storage section of the developing device is detected as the capacitance value between a predetermined wire disposed inside the toner storage section and the ground. Therefore, during manufacturing at the factory, it was necessary to inspect and adjust the developing device in the process cartridge so that its capacitance value fell within the expected tolerance range.

On the other hand, if the timing for replacing the process cartridge is determined by relatively comparing the capacitance value of a new process cartridge and that of a used process cartridge, the above problem can be avoided. Or not?
In this case, when a plurality of process cartridges are used in parallel, there is a problem in that it is difficult to determine when to replace each process cartridge.

The present invention has been made in view of the above problems, and its purpose is to reliably detect when it is time to replace the developing device even if the detected value of the remaining amount of toner deviates from the expected value, and to To provide a toner remaining amount detection device that can reliably detect when to replace each developing device even when two developing devices are used in parallel.

(Means for Solving the Problem) In order to achieve the above object, the present invention detects the amount of toner remaining in the developing device, and when the remaining amount of toner in the developing device becomes less than a predetermined amount, the developing device The remaining toner amount detecting device includes a detecting means for emitting a signal according to the remaining amount of toner in the developing device, and a signal value from the detecting means regarding the initial amount of toner in the unused developing device and the developing device. a storage means for storing a unique ID number from the device; and a storage means for storing a unique ID number from the device;
For the developing device having the number, the signal value regarding the remaining amount of toner from the storage means and the detection means is compared, and when the signal value from the detection means or the signal value from the storage means fluctuates by a certain percentage, the output is output. and comparison means for emitting.

(Function) Since the initial amount of toner in an unused developing device is stored in the storage device via the detection device, the signal value from the storage device and the signal value regarding the remaining amount of toner in the development device from the detection device. The amount of toner in the developing device can be estimated by comparing them with the comparison means. Therefore, if the comparison means issues a signal to replace the developing device when the signal value from the detection means fluctuates by a certain percentage compared to the signal value from the storage means, it is possible to ensure that the developing device is replaced when toner has run out. It will be replaced with a new developing device.

In other words, even if there is an error in the detected signal value regarding the amount of toner remaining by the detection means and it deviates from the expected value, the remaining amount of toner in the developing device can be used as the signal value when new, with the error still present. Since the signal value is compared with the current signal value, it is possible to accurately determine whether it is time to replace the developing device.

Also, even when multiple developing devices are used in parallel,
Since the unique ID number of each developing device is stored in the storage means and the above-mentioned action is applied to the developing device having each ID number, it is possible to prevent toner having a predetermined ID number from running out. This makes it possible to reliably replace the old developing device with a new developing device.

(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 FIGS. 1 and 2.

FIG. 1 shows a cross section of a process cartridge 8 etc. installed in the main body of an image forming apparatus. In the figure, 1 is a photosensitive drum which is an image bearing member that rotates in one direction, and the circumference of the photosensitive drum 1 is A charger 2, a developing device 3, a transfer roller 4, a cleaning device 5, and the like are provided.

The developing device 3 includes a toner storage section 3a that holds toner T;
a developing roller 3b that attracts the toner T in the toner storage section 3a to its outer circumference by the action of magnetic force or the like, and rotates in a certain direction to supply the toner T to the electrostatic latent image on the photosensitive drum 1;
It is composed of a developing plate 3c and the like that regulates the layer thickness of the toner T adsorbed around the developing roller 3b to a constant value, and the toner T on the developing roller 3b that is regulated to a constant layer thickness.
When the developing roller 3b is turned toward the photosensitive drum L side, an AC developing bias voltage is applied from the AC power source 6 to the developing roller 3b, thereby supplying the toner on the developing roller 3b to the electrostatic latent image on the photosensitive drum L. It is.

The cleaning device 5 includes a cleaning plate 5a that rubs against the photosensitive tram 1 to remove residual toner on the photosensitive tram l.
and a waste toner storage section 5b for storing the waste toner removed by the cleaning plate 5a.
The remaining toner on the photosensitive tram 1 is cleaned and the photosensitive tram 1 is prepared for the next image formation.

That is, when the photosensitive tram 1 uniformly charged by the charger 2 is exposed to only image light from a scanning optical system (not shown), an electrostatic latent image is formed on the photosensitive tram 1. The electrostatic latent image is directed toward the developing device 3 as the photosensitive tram 1 rotates, and is visualized as a toner image by being supplied with toner T by the developing bag M3. Then, this toner image is transferred onto a transfer paper P via a transfer roller 4, and the photosensitive tram 1 after the transfer is cleaned of residual toner by a cleaning device 5 and is prepared for the next image formation.

The transfer paper P is fed from a paper feed cassette (not shown) to the photosensitive tram 1, and after receiving the toner image transferred from the photosensitive drum 1, is sent to a fixing device (not shown). The fixing device fixes the toner image.

Here, the photosensitive tram 1, charger 2. The developing device 3 and the cleaning device 5 are integrally assembled within a cartridge container 8a as a process cartridge 8, and are detachably disposed within the main body of the image forming apparatus. and,
When the photosensitive tram 1 reaches the end of its life, the toner T in the developing device 3 is used up, or the cleaning device 5 is full of waste toner, the entire process cartridge 8 can be replaced. It is also intended to make maintenance easier by allowing equipment to be replaced. still,
7 is a shutter for protecting the photosensitive tram 1.

Now, with reference to FIGS. 1 and 2, a toner remaining amount detection device 1O that prompts for replacement of the process cartridge 8 when the amount of toner in the developing device 3 has decreased below a predetermined amount will be described.

The toner remaining amount detection device 20 is installed in the toner container section 3 of the developing device 3.
a detection electrode 21 that detects the amount of toner in the developing roller 3b as a current value from the developing roller 3b; a converting means 22 that rectifies the current value from the detection electrode 21 and converts it into a voltage value; and an unused developing device. A nonvolatile first memory 24 that stores the initial current value between the developing roller 3b of the bag H3 and the detection electrode 21 as a voltage value via the converting means 22, and the voltage from the first memory 24 and the exchanging means 22. Comparing and determining means 23 which compares the values at regular time intervals and issues an alarm signal when the voltage value from the exchange means 22 or the voltage value from the first memory 24 becomes smaller by a predetermined percentage; In response to the alarm signal, a replacement display means 26 displays a lack of toner in the developing device 3 and prompts the user to replace the process cartridge 8, and a replacement display means 26 that displays a toner shortage in the developing device 3 and prompts replacement of the process cartridge 8; It is comprised of a non-volatile second memory 25 for storing the ID number of the process cartridge 8 in order to recognize the cartridge 8, and the like.

It is assumed that only the detection electrode 21 and the second memory 25 are installed in the process cartridge 8, and the others are installed in the main body of the image forming apparatus.

However, since the value of the current flowing from the developing roller 3b to the detection electrode 21 is affected by the surrounding temperature and humidity, the current value from the first detection electrode 21, that is, the voltage value from the conversion means 22, is compared to the standard temperature and humidity. Is there something that needs to be fixed? For this purpose, a temperature detector 28 and a humidity detector 29 are provided, and the voltage value from the converting means 22 detected at the temperature and humidity is corrected by the correcting means 27 to that corresponding to the standard temperature and humidity.

It is assumed that the comparison and determination means 23 and the correction means 27 are built into the microcomputer 30 or
0 has functions other than the comparison and determination means 23 and the correction means 27. Further, it is assumed that the replacement display means 26 is composed of an LED, a liquid crystal display device, or the like.

Here, the basic concept of detecting the remaining amount of toner by the remaining toner amount detection device 20 will be explained below.

Since a developing bias voltage is applied from the AC power supply 6 to the developing roller 3b of the developing device M3 during development (when toner is used), a voltage from the developing roller 3b to the detection electrode 21 disposed above the developing roller 3b is applied. A constant current flows. On the other hand, when the toner in the toner storage section 3a of the developing device 3 is consumed and there is a space where there is no toner in a part of the space between the developing roller 3b and the sensing electrode 21, the developing roller 3b moves away from the sensing electrode 21.
This causes fluctuations in the current value flowing through 1. Therefore, the current value for the developing device 3 in a new process cartridge 8 (when it is filled with toner T without any gap between the developing roller 3b and the detection electrode 21) and the used process cartridge 8 to the current value for the developing device 3, and if this value reaches a certain value, the developing bag M3
There is no toner T inside, and the process cartridge 8 must be replaced.

That is, using the expected absolute value of the current value flowing from the developing roller 3b to the detection electrode 21 of the unused developing device 3 as a reference, the absolute value is compared with the current value obtained from the currently used developing device H3, Compared to the conventional idea that the process cartridge 8 including the developing device M3 is replaced when the current value falls below a certain value, the process cartridge 8 is replaced because all current values are relative. Even if there is an error in this current value compared to the expected value due to manufacturing, the time to replace the process cartridge 8 can be accurately determined regardless of the error.

Next, the characteristic configuration of this remaining toner amount detection device fi20 will be explained.

Generally, when an image is formed using an image forming device, it is either done with black toner or not, or it is not just black toner.
There are cases where it is desired to form an image using red and blue toners as well. Furthermore, depending on the type of image, it may be desirable to form the image using toner with small particle size. Therefore, it is conceivable to prepare a plurality of process cartridges 8 according to the type of toner to be used, and to selectively install the necessary process cartridges 8 into the main body of the image forming apparatus to form an image.

In this case, if the characteristic 1 of the process cartridge 8 installed inside the main body of the image forming apparatus is not memorized, for example, the value of the current flowing from the developing roller 3b to the detection electrode 21 when not in use, the process Cartridge 8
It becomes difficult to calculate the replacement timing.

Therefore, each process cartridge 8 has a second memory 25.
If a new process cartridge 8 is installed in the main body of the image forming apparatus.

This process cartridge 8 is connected via the microcomputer 30.
The ID number of the process cartridge 8 is input and stored in the second memory 25, and if this process cartridge 8 is used from now on, the second
Based on the signal from the memory 25, the microcomputer 30 or the ID
I was able to recognize the number.

That is, in the case of a new process cartridge 8, a number such as 0 is stored in the second memory 25, and when the microcomputer 30 detects this O, it is recognized as a new process cartridge 8, and the microcomputer 30 For example 1
The ID number is input into the second memory 25, and the current value flowing from the developing roller 3b to the detection electrode 21 is stored in the first memory as a voltage value via the exchange means 22. Note that the first memory 24 has a storage area for each ID number, and if the process cartridge 8 with a specific ID number reaches the end of its replacement life due to lack of toner, that ID number will be saved.
A new numbered Floss cartridge 8 is to be given.

When a new process cartridge 8 containing a different type of toner is installed in the main body of the image forming apparatus, ID'l1 is input from the microcomputer 30 and stored in the second memory 25, and this process At the stage when an image is formed in the cartridge 8, the initial current value flowing from the developing roller 3b to the detection electrode 21 is converted into a voltage value via the converting means 22 and stored in the storage area corresponding to the ID number of the first memory 24. be done. Then, the comparison and judgment means 23 determines the value of the ratio between the voltage value based on this initial current value and the voltage value sent every moment via the detection electrode 21 and the conversion means 22. After comparison and consideration, if the value of this ratio reaches a predetermined value, an alarm signal is issued from the comparison/judgment means 23 to the replacement display means 26, and the replacement display means 26 indicates that the process cartridge 8 should be replaced because there is no toner in the developing device 3. A message will be displayed indicating that it should be replaced.

On the other hand, when multiple types of process cartridges are installed in and removed from the main body of the image forming apparatus, the microcomputer 30 or the ID number from the second memory 25 of the process cartridge 8 installed in the main body of the image forming apparatus Upon receiving the signal, a voltage value signal based on the initial current value in the first memory 24 corresponding to the ID number is sent to the comparison/judgment means 23. Therefore, no matter how many types of process cartridges 8 there are, the amount of toner in the developing device 3 is detected for each process cartridge 8, and the remaining toner amount detection device 20 can reliably detect when it is time to replace the process cartridge 8. The Rukoto.

In the above case, the voltage value from the conversion means 22 is corrected from the temperature and humidity conditions from the temperature detection means 28 and humidity detection means 29 to the standard temperature and humidity conditions, and then It is input to the memory 24 and also to the comparison and determination means 23.

As described above, the toner remaining amount detection device M20 allows the replacement life of the process cartridge 8 in response to toner shortage to be reliably grasped, and also allows multiple process cartridges 8 to be used in parallel for the main body of the image forming apparatus. Even in such a case, it is possible to reliably grasp the replacement life of each process cartridge 8 in case of toner shortage.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. 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 second memory 25 is configured not by a memory element but by a fuse.

That is, as shown in FIG. 4, for example, three fuses 2
5a, 25b, 25c are attached to the process cartridge 8 as the second memory 25, and if the process cartridge 8 is new and unused, all the fuses 25a, 2
5b and 25c are brought into conduction to make the microcomputer 30 recognize that the process cartridge 8 is new.

When an image forming operation is started using this process cartridge 8, in order to give an ID number to this process cartridge 8, for example, an overload current is applied to the fuse 25a to disconnect it. The microcomputer 30 is made to recognize the number 1, and the voltage value from the conversion means 22 based on the initial current value from the developing roller 3b to the detection electrode 21 is
It is stored in the area of ID number l of the memory 24.

When the process cartridge 8 runs out of toner and reaches the end of its replacement life, the comparison and determination means 23 issues an alarm signal to the replacement display means 26, prompting the process cartridge 8 to be replaced.

As described above, the same effects as in the first embodiment can be obtained in this embodiment as well.

In the case of this embodiment, since only three fuses 25a, 25b, 25CL/ are provided as the second memory 25, only three process cartridges 8 can be accommodated, or if the number of fuses is increased, more processes can be accommodated. The cartridge 8 can also be used.

Above is the first part. Regarding the second embodiment, the case where the developing device 3 is incorporated in the process cartridge 8 has been described, but it is not limited to this, but the developing device 3 itself is detachably disposed in the device main body of the image forming apparatus. It goes without saying that the present invention can also be applied to cases where it is difficult to use.

In addition, in the above first and second embodiments, the developing device 3
The amount of toner remaining in the developing roller 3b is detected by the value of the current flowing from the developing roller 3b to the detection electrode 21.
Of course, the remaining amount of toner may be detected by measuring the capacitance value between a pair of electrodes.

(Effects of the Invention) As is clear from the above description, according to the present invention, even if the detected value of the remaining amount of toner deviates somewhat from the expected value, a developing device that has run out of toner can be reliably replaced with a new developing device. In addition, even when multiple developing devices are used in parallel, by assigning a unique ID number to each developing device, it is possible to reliably replace a developing device that has run out of toner with a predetermined ID number with a new developing device. I can exchange it with

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a process cartridge whose replacement time is determined by the toner remaining amount detection device according to the first embodiment, FIG. 2 is an explanatory block diagram of the same toner remaining amount detection device, and FIG. FIG. 4 is a block diagram for explaining the remaining toner amount detection device according to the second embodiment.
It is a detailed diagram of a memory, etc. 3...Developing device, 20...Remaining toner amount detection device. 22... Conversion means (detection means), 23... Comparison determination means (comparison means), 24-... First memory (storage means). Figure 1

Claims (3)

[Claims] (1) In a toner remaining amount detection device that detects the amount of toner remaining in the developing device and prompts for replacement of the developing device when the remaining amount of toner in the developing device becomes less than a predetermined amount, the toner remaining amount in the developing device is a detection means for emitting a signal according to the remaining amount of toner; a storage means for storing a signal value from the detection means regarding the initial amount of toner in an unused developing device and a unique ID number from this developing device; For the developing device having the number, the signal value regarding the remaining amount of toner from the storage means and the detection means is compared, and when the signal value from the detection means fluctuates by a certain percentage compared to the signal value from the storage means, output is performed. 1. A toner remaining amount detection device comprising: comparison means for emitting a toner amount. (2) The developing device is provided with an ID number storage means for storing a unique ID number, and when an unused developing device is installed in the main body of the image forming apparatus, the unique ID number is stored as an ID number from the device main body side. 2. The toner remaining amount detecting device according to claim 1, wherein the toner remaining amount detecting device is inputted into a number storage means. (3) The remaining toner amount detecting device according to claim 1 or 2, wherein the developing device is incorporated in a process cartridge that is removably disposed within the main body of the image forming apparatus.