JPH0990733A - Toner supply device of image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform toner end display and its release with high accuracy by judging the toner end or the like when an output change width of a magnetic sensor to detect magnetic permeability of a developer is larger than a prescribed value when toner is replenished. SOLUTION: A magnetic sensor 306 arranged in a developing hopper 301 or on a hopper wall, outputs electric power corresponding to magnetic permeability of a developer to be carried. When toner is supplied from a toner replenishing part 304 while agitating the developer by rotating agitating screws 302a and 302b, just after the toner is replenished, a developer whose toner density is locally large moves along the vicinity of the magnetic sensor 306, and magnetic sensor output voltage temporarily reduces, and returns to ordinary voltage in a uniformly dispersed condition. When a residual toner quantity in a replenishing toner vessel is little, since only a small quantity of toner is supplied, a reduction quantity of output voltage of the magnetic sensor 306 also reduces. Release of the toner end is judged by using an output change in this magnetic sensor 306.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner supply device for an image forming apparatus, and more particularly to a toner for an electrophotographic image forming apparatus using a toner used in an image processing apparatus such as a copying machine, a scanner, and a fax machine. The present invention relates to a toner end signal generating means of a supply device.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, an electrostatic latent image formed on the surface of a photoconductor is made to adsorb the toner of a charged developer and is transferred to a transfer paper so as to come into contact with the photoconductor drum. It is generally configured so as to complete transfer by transferring and heat fixing processing. As the developer, the toner is magnetized by mixing the toner with magnetic powder called carrier, and only the toner is adsorbed to the electrostatic latent image on the surface of the photoconductor drum. Therefore, since the toner in the developer decreases when the image forming process is executed, such an image forming apparatus is provided with means for detecting the remaining amount of the developer, and the remaining amount of toner in the toner hopper falls below a certain amount. Then, the replenishing operation is performed from the toner container. Further, the toner container contains replenishment toner, and when the remaining amount is low, a warning display is displayed to prompt replenishment of the toner or replacement of the toner cartridge. Such a warning display is generally called a toner end display, and the toner end display is automatically canceled when the toner supply is completed or the toner cartridge is replaced and the toner is replenished. In order to automatically cancel the toner end display, a means for detecting that the toner is normally supplied is required, but conventionally, a dedicated mechanism or electric circuit for that purpose has been provided. However, with the recent demand for downsizing and cost reduction of the apparatus, the structure has been simplified, and a toner end display canceling means that is simple and operates accurately has been required. For this reason, a large number of sensors provided for the purpose of performing other functions,
For example, by diverting a sensor for detecting the density of the transferred image,
Although it is proposed to perform the toner end display cancellation processing, the downsizing of the device is further advanced, and these sensors tend to be omitted, and the toner end cancellation is performed by a simpler means. There is a need.

[0003]

Conventionally, in order to respond to this demand, for example, in the case of using the dry two-component developer as described above, the magnetism of the carrier is utilized and the toner concentration in the developer is determined by the magnetic sensor. Those that perform control have been proposed. In this method, when the density does not increase even after performing the toner replenishing operation, it is determined that the toner is in the toner replenishment container, and it is determined that the toner is out, and a new addition of toner or replacement of the toner cartridge is prompted.
When it is confirmed that the density has increased in the subsequent density detection, the toner end display is canceled. According to this means, it is possible to achieve the objectives of toner density control and toner end detection / cancellation with a simple configuration using only a magnetic sensor, which is effective in reducing the cost. But,
In order to accurately perform the toner end and its release, it is necessary to continue the toner replenishing operation in a state where the toner is not consumed for a certain period of time, that is, the copying operation is stopped for a certain period of time.
This is because if the detection is performed while the copying operation is being performed, if the toner consumption amount exceeds the replenishment amount during the toner replenishment, the toner concentration may decrease without increasing. This is because the toner end display may occur even if the remaining amount of toner is not sufficient.

Further, when the toner end is temporarily displayed when the toner container for replenishing toner is almost empty, the toner adhering to the inner wall of the container drops due to vibration and the like, and the end display is released by a little replenishment, and the copying operation is further performed. As the end is displayed again with the continuation of, an unstable display may be made, which causes user's confusion.
As described above, if the toner end display and its cancellation are not performed with high accuracy, the end display and its cancellation are frequently switched in the boundary state, which not only confuses the user, but also as described above. When a high-quality copy that consumes a large amount of toner is made, if the toner density suddenly decreases, a toner replenishment process that interrupts the copying operation is performed even if there is a sufficient remaining toner amount. Is forced to run,
This will result in a long wait. The present invention solves the above-described problems in the toner supply device of the conventional image forming apparatus, and provides a toner supply device that can perform the toner end display and the release thereof with extremely high accuracy by a simple configuration and means. It is an object.

[0005]

In order to achieve the above object, the toner supply device of the image forming apparatus of the present invention has the following structure. According to the first aspect of the invention, in a photographic image forming apparatus using a dry two-component developer in which toner is mixed with a carrier having magnetism in order to visualize an electrostatic image formed on a photoreceptor, A magnetic sensor for detecting the magnetic permeability, a means for stirring the supplied toner, and a means for detecting the magnetic sensor output during the toner replenishing operation and determining the toner end release or the toner end when the change width is larger than a predetermined value. It is characterized by having. According to a second aspect of the present invention, in the toner supply device of the image forming apparatus, the predetermined value of the change width of the output of the magnetic sensor is set to a value larger than the change width in the toner end state.

According to a third aspect of the present invention, in a photographic image forming apparatus using a dry two-component developer in which toner is mixed with a magnetic carrier in order to visualize an electrostatic image formed on a photoreceptor, A magnetic sensor for detecting the magnetic permeability of the developer, a means for stirring the supplied toner, a means for detecting the output of the magnetic sensor during the toner replenishing operation and detecting the range of change thereof, and the toner container when the toner container is in the end state. Means for storing the magnetic sensor output change width when replenishing the toner and the sensor output change width for toner replenishment after the toner container is replaced, and the change width of the magnetic sensor output during the toner replenishment operation becomes the stored change width. It is characterized in that it is provided with a means for judging toner end release or toner end when it is larger than a predetermined value set based on the above.

According to the invention of claim 4, claims 1 to 3
In the toner supply device of the image device described above, the reference value for detecting the output width of the magnetic sensor is a value at the time of starting toner supply. According to a fifth aspect of the present invention, in the toner supply device of the image forming apparatus according to the first to fourth aspects, as an output value for detecting the magnetic sensor output width, a predetermined time after the toner replenishment is started has elapsed. It is characterized in that the value is used.
Further, in the inventions of claims 6 to 8, claims 1 to 3
In the toner supply device of the image forming apparatus described above, the change rate of the magnetic sensor output value is used instead of the change width of the magnetic sensor output value.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the illustrated embodiments. In the embodiment shown here, although not shown in the drawings, an electrostatic latent image is formed by irradiating the surface of the photoconductor drum with laser light guided from the image reading means via an optical mirror. Developing device, transfer polarization charger, cleaning unit, charge eliminating lamp, charging charger, paper feed registration roller, fixing roller, toner cartridge,
An example is a copying machine configured so that a toner image is transferred onto a conveyed sheet by a sheet feed sensor, a sheet discharge sensor, and the like. The developer used in this example is a mixture of toner and magnetic powder that is a carrier. The toner in the developer is charged to the opposite polarity to the polarity charged on the photosensitive drum, so that only the toner is It is adapted to be attracted to the electrostatic latent image formed on the surface of the photosensitive drum. Therefore, the toner decreases with the copying process, and the ratio of the toner in the developer decreases. To detect the ratio of toner in the developer, that is, the toner concentration, the magnetic permeability of the developer may be detected. For this reason, a magnetic sensor is used in the present invention, but when the toner concentration in the developer is low, the carrier ratio is high, so the permeability of the developer is high and the output level of the magnetic sensor is high. Depending on the configuration of the magnetic sensor, conversely, if the carrier ratio decreases, the sensor output may decrease accordingly.
Any of the characteristics can be put into practice in the present invention.

In order to facilitate understanding of the present invention, the relationship between toner concentration and magnetic sensor output will be described in detail. FIG. 1 is a diagram showing an example of the output characteristics of the magnetic sensor. In this example, the output voltage value saturates at a large value in the range where the toner density is low, and the sensor output voltage value gradually decreases as the density increases. In the range where the density is higher, the output voltage value is saturated at a small value.
A means for detecting the toner concentration in the developer with high accuracy is extremely important for forming a high quality image, but the sensitivity of the magnetic sensor currently available is small and the range that can be detected by one Is limited to an extremely narrow range compared to the total volume of the toner hopper, and the obtained detection result indicates only the local concentration of the toner hopper. Toner is generally replenished from the opening provided in a part of the stirring container of the toner hopper, so in the method of simply detecting the toner concentration by the magnetic sensor arranged in the vicinity of the opening, the supplied toner is supplied to the carrier in the hopper. Therefore, it is not possible to detect the concentration in a state of being uniformly stirred, and after the toner is supplied, the toner is gradually and uniformly mixed with the stirring operation.

FIG. 2 is a diagram showing how the output voltage of the magnetic sensor changes when the toner is replenished in the empty toner hopper with the replenishment operation. That is, as apparent from the magnetic sensor characteristics shown in FIG. 1, the magnetic sensor output saturates at the high voltage Va while the amount of toner in the developer is small. When the toner replenishing operation is performed in this state, the toner concentration of the developer locally rises, and the sensor output sharply decreases when this portion passes the magnetic sensor arrangement position. Disperse evenly throughout the developer. As a result, the sensor output rises again and becomes constant at the predetermined voltage value Vb. In FIG. 2, Vc is an output voltage value when the toner density around the sensor is maximum, and the difference between Va and Vb is ΔVab, and the difference between Va and Vc is ΔVac. The time until the toner is uniformly agitated depends on the agitation function, and various measures have been made to make the toner evenly as quickly as possible, but even if the time is shortened, the sensor as shown in FIG. There is no difference in presenting a change in the output voltage, and the above-mentioned inconvenience cannot be eliminated. Conventionally, the detection by the magnetic sensor is based on the above Va and Vb, and the decrease to the above voltage Vc is regarded as an undesired voltage change. However, in the present invention, this voltage Vc is detected and ΔVac is detected as the toner end. It is used as a judgment standard of.

FIG. 3 is a schematic view of the essential parts of a developing device to which the present invention is applied. In this example, two stirring screws are used to convey the developer in mutually opposite directions so that the developer is circulated in the developing hopper. It has a function of uniformly stirring the toner and the carrier. In the figure, reference numeral 301 denotes a developing hopper, which is divided into two cylindrical chambers by a partition plate 305 and is connected by openings provided at both ends of the partition plate 305. Further, agitating screws 302a and 302b are arranged in the respective cylindrical chambers so that they are rotated in opposite directions by a driving device (not shown), and the toners are respectively passed through the openings in the directions of the arrows. It is designed to be transported. Further, reference numeral 303 in the drawing denotes a developing roller which is disposed in the vicinity of the photoconductor,
Reference numeral 304 denotes a toner replenishing unit connected to a toner replenishing device (not shown), and the stirring screw 3 is provided in the replenishing unit.
The end portion of 02b extends and the supplied toner is supplied to the developing hopper 3
It is supposed to be sent to 01. Further, reference numeral 306 is a magnetic sensor arranged in the developing hopper or on the wall of the hopper, which outputs a voltage corresponding to the magnetic permeability of the developer being conveyed.

In the developing device thus constructed, when the toner is supplied while rotating the two stirring screws 302a and 302b to stir the developer, the toner density is locally large immediately after the toner is replenished. The agent moves in the vicinity of the magnetic sensor, gradually disperses in the carrier while circulating in the direction of the arrow, and is homogenized, so that the output voltage of the magnetic sensor temporarily drops and returns to the normal voltage in a uniformly dispersed state. To do. If a sufficient amount of toner remains in the toner container for replenishment, the required amount of toner is supplied, but if the amount of remaining toner in the container is small, only a small amount of toner is supplied. Reduces the output voltage of the sensor.

FIG. 4 illustrates this state. When the amount of remaining toner in the replenishment toner container is large and the amount of replenishment is large, the sensor output decreases to Vf and the voltage drop amount becomes ΔVdf. If the amount is small, the amount of toner supplied is small and the sensor output drops only to Ve.
It becomes de. In the example shown in FIG. 4, the voltage change before toner replenishment and the amount of voltage change when the toner is sufficiently uniformly stirred after replenishment are zero, but this is because the toner hopper before replenishment is empty during normal copying operation. This is because the toner amount before and after replenishment is the same. As described above, it is not preferable that the sensor output value fluctuates due to the remaining amount of the toner replenishing container, and it has been devised so far that it is not affected by the control of the CPU or the like, or the stirring ability is increased. .

On the contrary, according to the present invention, the toner end cancellation is determined by positively utilizing the sensor output change due to the difference in the residual amount in the toner supply container. That is, the amount of decrease in the sensor output before and after the toner replenishing operation is, for example, ΔVde shown in FIG.
The configuration is such that the toner end display is canceled when it changes to Vdf. That is, when the toner end display is performed and the toner cartridge is replaced in response to this, a larger amount of toner will be supplied in the subsequent toner supply operation compared to before the replacement, so ΔVdf in FIG. Is detected, the toner end is released by detecting this.

According to this means, the toner density can be directly detected with a simple structure, so that the toner end can be released accurately without providing any other complicated sensing mechanism. Specifically, the change in the sensor output after the toner end display is known in advance, a predetermined voltage change width is appropriately set, and the toner end is released when the set value is exceeded.

According to the second aspect of the invention, the toner end is detected based on the same principle. That is, as described above, when the remaining amount in the toner replenishing container becomes small, the sensor output voltage decrease amount after the replenishment operation becomes small. As described above, the sensor output is detected before and after the toner replenishment operation, and the decrease amount is When it becomes smaller than a certain value, for example, Vde in FIG. 4, it is determined that the toner is out and the display is performed. In addition to the toner end display, there are various methods of use. For example, when the toner end is being displayed and the residual toner adhering to the inner wall of the replenishment container due to vibration before the toner cartridge is replaced slips off and is supplied, the toner concentration temporarily recovers and the toner is not replenished. As described above, the problem that the toner end is released despite the fact that it has not been done occurs. Therefore, after the toner end display is once performed, if there is no change in the sensor output value equal to or more than a predetermined value, for example, Vde or more in FIG. 4, the toner end is not released even if the sensor output value decreases. If controlled to, it is possible to prevent the occurrence of the above problems. For example, as shown in FIG. 5, as a sensor output value, Ve ′ is between Ve and Vf.
And Vf 'are set, and the output change width Δ to judge that the end is released
Vdf ′> ΔVde + α (where α> ΔVde′−ΔVde and ΔVdf ′ ≦ ΔVdf).

Depending on the toner replenishing mechanism, the shape of the toner container, and the physical properties of the toner, the toner replenishing amount when the toner container is almost empty (toner end state) or the toner replenishing amount immediately after the toner container replacement (new toner container) is used. There are variations, and it may be difficult to make an accurate determination. The invention described in claim 3 is effective as a countermeasure. That is, the sensor output change Vde at the toner end time is stored, and the difference between it and the next detected output change width ΔVnxt is shown in FIG.
When the value falls within the range of the value shown in, it is determined that the toner container has been replaced. FIG. 6 shows the relationship between the toner supply amount and the toner amount in the container when the toner container is just replaced (new) and in the end state, and shows the maximum value of the dispersion of the supply amount at the toner end. When the difference between Vemax and the minimum value Vfmin of the variation of the supply amount of the new container is β or more, that is, when the relationship of ΔVnxt−ΔVde ≧ β is satisfied, it is determined that the toner container is replaced, and the toner end is determined. Cancel. Note that the output voltage value of the magnetic sensor is rarely obtained stably as shown in FIGS. 2 and 4, and is actually shown in FIG. 7 due to various noises and toner agitation. Often includes small fluctuations, and if a fluctuating sensor output value is used as a reference value for each set value described above, the operation becomes unstable. Therefore, in order to eliminate such a defect, the sensor output used as the reference value as described in claim 4 may be set to the value at the time when the toner replenishment signal is output. According to this method, even if there is a slight change in the sensor output value after that, the operation is stable without being affected by it.

Generally, the toner density is low at the end of toner or after the toner container is replaced, and the toner is continuously replenished to restore the standard density. At this time, if the replenishment interval is long, there is no problem, but if the replenishment interval is short,
The sensor output change as described above continuously occurs. Therefore, in the present invention, it may be difficult to determine which is a true value even if it is attempted to extract a subsequent output change with respect to the reference signal from the sensor to be detected.
Therefore, as described in claim 5, the value when a predetermined period has elapsed after the reference value is set may be adopted.
That is, the time required for the replenished toner to pass through the sensor is substantially constant and can be known in advance. Therefore, if the timing for monitoring the sensor output is limited to a certain time corresponding to the above time, it is necessary. The output value of the sensor can be obtained. FIG. 8 is a diagram simulating the relationship between the passage of time and the sensor output value, where t0 is, for example, the start time of the nth supply operation, and the sensor output value value is approximately the same time after the toner replenishment operation is started. The pattern in which the toner drops, that is, the supplied toner passes the sensor position is repeated. Therefore, the desired true value can be obtained by obtaining the sensor output during the period before and after the timing when the voltage becomes the minimum value in this cycle.

If there is a large fluctuation in the sensor output when the toner replenishing operation is not performed, or if the effect of the toner replenishing performed before that remains, the reference sensor output may not be obtained. . In this case, claim 6
As described above, in place of the sensor output change width of the previous embodiment, the change rate of the sensor output over time is obtained, and if the same process is performed, accurate toner end release or toner end detection can be performed. You can That is, with respect to the sensor output change as shown in FIG. 9, the rate of change of the output value per unit time or in a predetermined time r = (V1−V
With 2) / Δt, the same function as in each of the above-described embodiments can be achieved.

Further, when applying this idea to the invention according to claim 2, if the toner end is released with the change rate of the output change rate + α when the toner end is detected, erroneous detection due to a temporary increase in density is prevented. It can be done (Claim 7). Further, in order to apply the change rate to the invention described in claim 3, the change rate at the time of toner end is stored, and when the difference from the change rate thereafter becomes a predetermined value or more, the container is replaced. If it is determined that the end is satisfied, the end can be reliably released without affecting the variation in the rate of change of the replenishment mechanism or the like.

[0021]

Since the present invention is constructed as described above, the following effects can be obtained respectively. That is, according to the first aspect of the invention, the toner density is detected by the magnetic sensor output change width and the toner end cancellation is determined. Therefore, the accurate end display cancellation can be performed with a simple configuration. Further, if the magnetic sensor used for other purposes such as concentration detection is diverted, the cost increase is extremely small. According to the second aspect of the present invention, in addition to the effect of the above-described invention, it is possible to prevent the malfunction of the end release due to the residual toner after the toner end is detected, and the malfunction of the end release when the image formation with a large amount of toner consumption is performed. Become. Further, in the third aspect of the invention, the end release can be accurately performed without being affected by the variation in the toner replenishment amount.

According to the fourth aspect of the present invention, the sensor output value serving as the determination reference is specified at a predetermined timing. Therefore, even if the sensor output fluctuates, it is possible to accurately determine the end release or the end. According to the fifth aspect of the present invention, the sensor value for detecting the sensor output change width is detected within a certain period after the lapse of a predetermined time. Therefore, even if the toner replenishment interval is narrow, a true value is obtained. Can be detected. In the inventions according to claims 6, 7, and 8, since the change rate is adopted instead of the width of the sensor output value, the end release and the end determination can be accurately performed even when the sensor output varies.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of output characteristics of a magnetic sensor used in the present invention.

FIG. 2 is a diagram showing a characteristic example of a magnetic sensor used in the present invention.

FIG. 3 is a structural view showing an embodiment of a developing device used in the present invention, (a) is a side view and (b) is a front view.

FIG. 4 is a diagram showing a magnetic sensor output characteristic for explaining an embodiment of the present invention.

FIG. 5 is a diagram showing output characteristics of a magnetic sensor for explaining another embodiment of the present invention.

FIG. 6 is a diagram showing an example of a relationship between a toner amount in a toner container and a replenishment amount door for explaining a modified embodiment of the present invention.

FIG. 7 is a magnetic sensor output waveform diagram for explaining another embodiment of the present invention.

FIG. 8 is a magnetic sensor output waveform diagram for explaining another embodiment of the present invention.

FIG. 9 is a magnetic sensor output waveform diagram for explaining another embodiment of the present invention.

[Explanation of symbols]

301 ... Development hopper, 302a, 302b ...
Stirring screw, 303 ... Developing roller, 304 ...
・ Toner supply unit, 305 ... Partition plate, 306 ...
Magnetic sensor.

Claims (8)

[Claims] 1. A dry type 2 in which a toner is mixed with a magnetic carrier in order to visualize an electrostatic image formed on a photoreceptor.
In a photographic image forming apparatus that uses a component developer, a magnetic sensor that detects the magnetic permeability of the developer, a stirring unit that stirs the supplied toner, and a change range that detects the magnetic sensor output during toner replenishment operation. And a means for releasing the toner end when the value is larger than a predetermined value. 2. The toner supply device for an image forming apparatus according to claim 1, wherein the predetermined value of the change width of the output of the magnetic sensor is set to a value larger than the change width in the toner end state. Toner supply device for image forming apparatus. 3. A dry type 2 in which a toner is mixed with a magnetic carrier in order to visualize an electrostatic image formed on a photoreceptor.
In a photographic image forming apparatus that uses a component developer, a magnetic sensor that detects the magnetic permeability of the developer, a stirring unit that stirs the supplied toner, and a change range that detects the magnetic sensor output during toner replenishment operation. Means for detecting
The magnetic sensor output change width when the toner container is replenished with toner in the end state and the means for storing the sensor output change width with respect to the toner replenishment after toner container replacement are provided, and the change of the magnetic sensor output during the toner replenishment operation A toner supply device for an image forming apparatus, comprising means for determining toner end release or toner end when the width is larger than a predetermined value set based on the stored change width. 4. The image forming apparatus according to any one of claims 1 to 3, wherein the reference value for detecting the magnetic sensor output width is a value at a toner supply start time. Device toner supply device. 5. The toner supply device for an image forming apparatus according to claim 1, wherein the output value for detecting the magnetic sensor output width is a value after a predetermined time has elapsed from the start of toner replenishment. A toner supply device for an image forming apparatus characterized by the above. 6. The toner supply device for an image forming apparatus according to claim 1, wherein a change rate of the magnetic sensor output value is used in place of the change width of the magnetic sensor output value. Toner supply device. 7. The toner supply device for an image forming apparatus according to claim 2, wherein a change rate of the magnetic sensor output value is used instead of the change width of the magnetic sensor output value. Toner supply device. 8. The toner supply device for an image forming apparatus according to claim 3, wherein a change rate of the magnetic sensor output value is used instead of the change width of the magnetic sensor output value. Toner supply device.