JPS61170764A - Toner remaining quantity detecting device - Google Patents

Abstract

PURPOSE:To detect the remaining quantity of a toner in a toner hopper by detecting a toner mixing ratio of a developer in a developing device by a variation in magnetic permeability of the developer. CONSTITUTION:A magnetic sensor 50 is constituted of a detecting head 51 for contacting a developer in a developing device and detecting the magnetic permeability of the developer, an amplifier 52, an oscillator 53, a phase comparator for executing a comparison in phase difference of a reference phase signal outputted from this oscillator 53 with a detecting signal amplified by the amplifier 52, and a low-pass filter 55. The larger a toner mixing ratio becomes, the smaller an output voltage of a magnetic sensor 50 becomes. As for the output voltage of the magnetic sensor 50 to an optimum toner mixing ratio Tc for obtaining an image of good quality, the output voltage of the time when the toner quantity has become small, and the output voltage of the time when the toner has come not to be carried at all are derived, set as a comparing voltage of a voltage comparator 56, and compared with the present output voltage of the magnetic sensor 50. In this way, the remaining quantity of the toner in the toner hopper can be detected more exactly.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a toner remaining amount detection device for detecting the remaining amount of toner in a toner replenishing means that replenishes toner to a developing device in an image forming apparatus such as a copying machine. Regarding.

[Technical Background of the Invention] Conventionally, as this type of toner remaining amount detection device, an actuator provided inside a toner hopper that stores replenishment toner approaches a reed switch provided on the side of the toner hopper as the amount of toner decreases. However, a reed switch is used in which a magnet attached to the tip of the actuator turns on the reed switch.

[Problems with Background Art] However, in such conventional toner remaining amount detection devices, the reed switch is turned on before the toner in the toner hopper is completely exhausted, making it difficult to accurately detect the remaining toner amount in the toner hopper. Not only can't you do it,
When converting the toner hopper into a cartridge, it is difficult to simplify the shape of the toner hopper, which leads to an increase in cost.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to more accurately detect the amount of toner remaining in the toner hopper, and to simplify the structure of the toner hopper, thereby reducing costs. An object of the present invention is to provide a toner remaining amount detection device that can detect the amount of remaining toner. [Summary of the Invention] In order to achieve the above object, the present invention detects the amount of toner remaining in the toner hopper by detecting the toner mixing ratio of the developer in the developing device based on the change in magnetic permeability of the developer. It is configured as follows.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 5 shows a copying machine as an example of an image forming apparatus equipped with the toner remaining amount detection device of the present invention)b, tfh
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．． r A document table 2 is provided on the top surface, and this document table 2
A document feeder 3 is provided above so as to cover the upper surface of the document feeder 3 so as to be openable and closable. A paper feed cassette 4, 5, 6 is mounted on the right side of the main body 1, and a paper discharge tray 7 is mounted on the left side. Note that the cassette cover of the paper feed cassette 4 in the first car serves as a manual paper feed tray 8 for manually feeding paper as appropriate. Further, a photoreceptor drum 9 is disposed approximately in the center of the main body 1, and around the photoreceptor drum 9, a charging device 10 and an exposure optical system 1 are arranged.
A 1.2-color developing device 12, a transfer charger 13, a peeling charger 14, a cleaning device 15, a static elimination lamp 16, and the like are arranged in this order. Here, the developing device 12 includes, for example, a first developing device 121 and a second developing device 122.
The first developing device 121 uses red (or yellow, blue, green, etc.) developer that is rarely used.
The second developing device 122 is designed to use a frequently used black developer. Note that the above developer is a two-component developer consisting of toner and carrier.

Then, by selectively driving the first developing device 121 and the second developing device 122, black or one color other than black (
For example, it is possible to perform color development (red). In addition, paper feed cassettes 4, 5, and 4 are provided at the bottom of the main body 1.
6 to paper feed row 517 and separation roller 1 for preventing double sheet taking
8 or manually fed from the manual paper feed tray 8, the paper is transferred to the paper output tray 7 via the image transfer section 19 between the photosensitive drum 9 and the transfer charger 13.
A paper conveyance path 20 is formed that leads to. An aligning roller 21 is disposed on the upstream side of the image transfer section 19 of the paper conveyance path 20, and a heat roller 22 and a paper discharge roller 23 as a fixing device are disposed on the downstream side.

The exposure optical system 11 includes an exposure lamp 24 that moves back and forth along the lower surface of the document table 2 in the direction of the arrow in the figure and irradiates the document with light.
, a first mirror 25 that reflects light reflected from the original in a predetermined direction, and the exposure lamp 24 and the first mirror 25.
A second mirror 27 and a third mirror 28 that move in the same direction at half the speed in synchronization with the first mirror 25 and reflect the reflected light from the first mirror 25 toward the lens unit 26, and the lens unit 26. Consists of a fixed fourth mirror 29 and a fifth mirror 30 that reflect the reflected light in a predetermined direction, and a fixed sixth mirror 31 that reflects the reflected light from the fifth mirror 30 toward the photosensitive drum 9 side. has been done.

Thus, the exposure lamp 24 and the first mirror 25 move along the lower surface of the document table 2, and in synchronization with this movement, the second mirror 27 and the third mirror 28 move in the same direction at half the speed. By moving, the photosensitive drum 9, which is rotated in advance, optically scans the original on the original platen 2.
An electrostatic latent image corresponding to the image of the document is formed on the photosensitive drum 9, which is uniformly charged by the charging device 10. The electrostatic latent image formed in this way is developed by facing the developing device 12 and turned into a developer image, and then sent to the image transfer section 19, where the developer is applied onto the sheet of paper fed by the aligning roller 21. The image is transferred. The paper to which this developer image has been transferred is separated from the photoreceptor drum 9 by the separation charger 14, and then guided through the paper transport path 20 to the heat roller 22, where the transferred image is fixed. The paper is discharged to the paper discharge tray 7 by the paper discharge roller 23. On the other hand, the surface of the photosensitive drum 9 after the developer image has been transferred onto the paper is cleaned of residual developer (toner) by facing the cleaning device 15, and the residual image is erased by a rough static elimination run 116. It is now ready for the next copy operation.

FIG. 4 shows, for example, the second developing device 122 in detail, and is equipped with a magnetic sensor for detecting the toner mixing ratio. That is, a magnetic roller (developing roller) 41 serves as a developer conveying means, and by forming a magnetic brush for the developer on its surface, it conveys the developer to the area to be developed, that is, the sliding contact area with the photoreceptor drum 9. do. Reference numeral 42 denotes a toner conveying device, which is composed of a toner conveying pipe 43 and a toner conveying shaft 44 that rotates within the toner conveying tube 43, and supplies toner from a toner container of a toner replenishing means (not shown).
1 into the developing device. 45 is a first developer stirring body;
The toner conveyed by the toner conveying device 42 is preliminarily stirred with the developer. A second developer agitator 46 stirs the developer. A doctor 47 regulates the thickness of the magnetic brush on the magnetic roller 41.

A developer rectifying member 48 receives the developer scraped off by the doctor 47 and creates a stable flow of developer toward a detection head 51 of a magnetic sensor 50, which will be described later. 49 is a casing that houses these parts.

Reference numeral 50 denotes a magnetic sensor, which is attached to the casing 49 with its detection head 51 exposed inside the developing device, and detects the toner mixing ratio of the developer received by the developer rectifying member 48 based on the magnetic permeability of the developer. It is designed to be detected based on changes in .

FIG. 1 schematically shows a residual toner layer detection device according to the present invention. That is, the magnetic sensor 50 includes a detection head 51 that comes into contact with the developer in the developing device and detects the magnetic permeability of the developer, an amplifier 52 that amplifies the minute output signal from the detection head 51, and the detection head 51. an oscillator 53 that outputs a drive and reference phase signal;
a phase comparator 54 that compares the phase difference between the reference phase signal outputted from the reference phase signal and the detection signal amplified by the amplifier 52;
It is composed of a low-pass filter 55 that shapes the waveform of the signal output from the phase comparator 54. The characteristics of the output voltage of the magnetic sensor 5o with respect to the developer/toner mixing ratio are shown in FIG. 2, and as the toner mixing ratio increases, the output voltage of the magnetic sensor 50 becomes smaller. Here, the output voltage of the magnetic sensor 50 for the optimum toner mixing ratio Tc to obtain a high-quality image is . The output voltage of the magnetic sensor 5o with respect to the toner mixture ratio Tb is (b), and the output voltage of the magnetic sensor 5o with respect to the toner mixture ratio Ta when the toner in the toner hopper is exhausted and no toner is conveyed into the developing device is
The output voltage of 0 is Va. These Va, Vb, and Vc are set as comparison voltages of the voltage comparator 56 and compared with the output voltage of the magnetic sensor 50. And magnetic sensor 5
When the output voltage of 0 becomes higher than the specified value Vc, the voltage comparator 56 outputs the toner replenishment signal S1. When the microprocessor 57 receives this signal S1, it turns on the toner replenishing motor 58 of the toner replenishing means, thereby replenishing toner from the toner hopper. Further, when the output voltage of the magnetic sensor 50 becomes higher than the specified value vb, the voltage comparator 56 outputs a toner amount decrease signal S2. When the microprocessor 57 receives this signal S2, it lights up the low toner indicator 59, thereby warning the user that the toner level in the toner hopper has decreased. Further, when the output voltage of the magnetic sensor 50 becomes higher than the specified value Va, the voltage comparator 56 outputs a toner empty signal S3. microprocessor 5
7 receives this signal S3, it lights up the toner empty indicator 60, thereby warning the user that the toner in the toner hopper is empty.

FIG. 3 shows changes in the toner replenishment signal S, toner amount decrease signal S2, and toner empty signal S3 due to changes in the state inside the toner hopper and the output voltage of the magnetic sensor 50 during actual copying. It is. When copying is performed, the toner mixing ratio of the developer decreases, and the magnetic sensor 50
The output voltage of increases. Then, at point A, when the toner mixing ratio of the developer falls below the appropriate level TC and the output voltage of the magnetic sensor 50 becomes higher than the specified value VC, the toner replenishment signal S1 is output, and the toner replenishment motor 58 is turned on. The developing device 121 is replenished with toner. In this way, feedback is performed so that the toner mixing ratio of the developer returns to the appropriate level TO. When the toner mixing ratio of the developer becomes higher than the appropriate level TC, the output voltage of the magnetic sensor 50 becomes lower than the specified value yc, the toner replenishment signal S1 is turned off, and toner replenishment is stopped. In this way, when there is toner in the toner hopper and the toner is being replenished normally, the toner replenishment signal 98"f)t>・t
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The mixing ratio is controlled to converge to an appropriate level TC.

When the toner in the toner hopper is consumed, the amount of toner consumed when forming an image from the developer and the amount of toner replenished from the toner hopper to the developer become unbalanced. In other words, when the toner in the toner hopper decreases,
Despite toner replenishment, the toner mixing ratio of the developer continues to decrease. At this time, the output voltage of the magnetic sensor 50 gradually increases. Then, at point B, when the toner mixing ratio of the developer falls below the appropriate level Tb and the output voltage of the magnetic sensor 50 becomes higher than the specified value vb, a toner amount decrease signal S2 is output, and the toner amount decrease indicator 59
lights up to warn the user that the amount of toner in the toner hopper is decreasing. Here, the specified value vb is specified at a value higher than a voltage value at which the output voltage of the magnetic sensor 50 overshoots when there is toner in the toner hopper and toner supply is balanced.

When the toner in the toner hopper is further consumed and there is no toner, the toner mixing ratio of the developer further decreases and the output voltage of the magnetic sensor 50 increases. Then, at point 0, when the toner mixing ratio of the developer falls below the appropriate level Ta and the output voltage of the magnetic sensor 50 becomes higher than the specified value Va, a toner empty signal S3 is output, and the toner empty indicator 60 lights up. to warn the user that the toner in the toner hopper is empty, and
Stop the copying operation of the copying machine. Here, the above specified value v
a shows the magnetic sensor 5 at the lowest toner mixing ratio at which developer adhesion to paper does not occur due to a decrease in the toner mixing ratio of the developer.
It is defined by an output voltage of zero.

With the configuration described above, compared to conventional devices, it is possible to more accurately detect that the toner is running out in the toner hopper, and the degree of freedom in the shape of the toner hopper, etc. is increased when converting the toner hopper into a cartridge. In addition, it is easy to reduce the cost of the toner hopper. Moreover, since the magnetic sensor detects a change in magnetic permeability due to a change in the mixing ratio of carrier, which is a magnetic material, and toner, which is a non-magnetic material, the amount of toner remaining in the toner hopper can be detected more accurately.

In the above embodiment, a case has been described in which the remaining amount of toner is detected in a toner replenishing means that replenishes toner to a developing device in a copying machine, but the present invention is not limited to this, and the present invention is not limited to this. In an image forming apparatus equipped with a developing device that performs development using a two-component developer,
Any device that detects the remaining amount of toner in a toner replenishing means that replenishes toner to a developing device can be applied.

[Effects of the Invention] As detailed above, the present invention provides a toner remaining amount detection device that can more accurately detect the amount of toner remaining in the toner hopper, simplify the structure of the toner hopper, and reduce costs. can be provided.

[Brief explanation of the drawing]

The drawings are for explaining one embodiment of the present invention. Fig. 1 is a block diagram schematically showing the remaining toner amount detection device according to the invention, and Fig. 2 shows the output voltage with respect to the toner mixing ratio of the magnetic sensor. A characteristic diagram, FIG. 3 is a timing chart for explaining the operation, and FIG. 4 is a longitudinal side view showing the developing unit in detail.
FIG. 5 is a longitudinal sectional front view schematically showing a copying machine to which the remaining toner amount detection device according to the present invention is applied. 9... Photosensitive drum, 12... Developing device, 121... First developing device, 122...
・Second developing device, 41... Magnetic roller (developer conveying means), 42... Toner conveying device, 47...
...Doctor, 48...Developer rectifying member, 5
0... Magnetic sensor, 51... Detection radar, 56... Voltage comparator, 57... Microprocessor, 58... Toner Supply motor, 60... Toner empty indicator.

Claims (5)

[Claims] (1) Toner that forms an image using a developing device that is equipped with a developer conveying means that conveys a two-component developer consisting of toner and carrier to a developing area, and replenishes toner to the developing device. In an image forming apparatus including a replenishing means, a magnetic sensor having a detection head exposed in the developing device and detecting a toner mixing ratio of the developer based on a change in magnetic permeability of the developer; and the developer conveying means a developer rectifying means that receives the developer on the top and creates a stable flow of the developer toward the detection head of the magnetic sensor; 1. A toner remaining amount detecting device, comprising: a signal generating means for generating a signal when the toner replenishing means is in use, and detecting the remaining amount of toner in the toner replenishing means based on the signal generated by the signal generating means. (2) The specified value includes a first specified value and a second specified value, and the signal generating means is configured to generate a signal when the toner mixture ratio detected by the magnetic sensor becomes lower than the first and second specified values. Each signal is generated, and the signal generated at the first specified value operates the toner replenishing means, and the signal generated at the second specified value causes an alarm or stops the operation of the image forming apparatus. A toner remaining amount detection device according to claim 1. (3) The remaining toner amount detection device according to claim 2, wherein the first specified value is set to a higher level than the second specified value. (4) The remaining toner amount detecting device according to claim 1, wherein the developer conveyance means is a magnetic roller that conveys the developer while rotating. (5) The remaining toner amount detection device according to claim 1, wherein the image forming device is a copying machine.