JPH04349481A - Rotation-type developing device in image forming device - Google Patents

Abstract

PURPOSE:To provide a rotation-type developing device capable of securely and steadily transferring a detection signal from the toner concentration sensor of each developing unit to the main body control part on the image forming device main body side, in the rotation-type developing device which is provided with the plural developing units and performs a development operation after bringing each developing unit into a development position by rotation. CONSTITUTION:Each developing unit 2Y is provided with a light emitting element 21Y which emits light according to a detection signal from the toner concentration sensor 18Y housed in each developing unit 2Y. A light receiving element 22 which receives the light is provided on the side of the image forming device main body 27. A toner replenishment operation is controlled by inputting the output of the light receiving element 22 to the main body control part 23.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a plurality of developing devices containing a two-component developer, is rotatably supported by the main body of an image forming apparatus, and any one of the plurality of developing devices is The electrostatic latent image formed on the latent image carrier is selectively brought to a developing position opposite to the latent image carrier, and a two-component developer contained in the developing device is used to convert the electrostatic latent image formed on the latent image carrier into a visible image as a toner image. The developing device is a rotary developing device used in an image forming apparatus that is becoming increasingly popular, and each developing device has a toner concentration sensor that detects the toner concentration of its two-component developer, and the detection signal of the sensor is transmitted to the main body of the image forming apparatus. The present invention relates to a rotary developing device in which toner is transferred to a main body control section provided therein, and the control section controls replenishment of toner to a developing device whose toner concentration has decreased.

0002

2. Description of the Related Art In a rotary developing device of the above type used in an image forming apparatus such as an electronic copying machine, a printer or a facsimile machine, one of the developing devices is selectively positioned at a developing position, and a latent image carrier is The electrostatic latent image formed on the image is visualized. Each developing unit may contain two-component developers containing toners of different colors to form a color visible image, or a plurality of developing units containing toners of the same color may be used, with each developing unit containing toners of different colors. form a visible image of the same color.

[0003] Such a rotary developing device is disclosed in Japanese Utility Model Application No. 58-146251, Japanese Utility Model Application No. 59-4549, Japanese Patent Application Publication No. 60-257459, and Japanese Patent Application No. 1988-
It is explained in detail in No. 223211, etc.

As each developing device performs the developing operation as described above, the toner of the two-component developer is sequentially consumed. detects the toner concentration of the developer, transfers the detection signal to the main body control section provided on the main body side of the image forming apparatus, and replenishes toner to the developing device where the toner concentration has decreased under the control of the control section. There is.

As mentioned above, the detection signal from the toner density sensor provided in each developing device is transferred to the main body control section of the image forming apparatus main body. Conventionally, electric wires have generally been used as such transfer means. It is used. That is, each toner concentration sensor and the main body control section are connected with electric wires, and the detection signals of the sensors are transferred to the main body control section.

However, as the name suggests, the rotary developing device rotates to selectively bring each developing device to the developing position, so the toner concentration sensor of the rotating developing device and the stationary main body control section are connected by electric wire. If connected, there is a risk that the electric wires will be twisted and cut due to the rotation of the developing device.

[0007] Although it is possible to fix the central shaft of the rotary developing device and pass an electric wire through it, there are cases where the shaft cannot be fixed, which limits the scope of its use.

Further, the rotary developing device is provided with contacts connected to each of its toner density sensors, and contacts that slide into contact with these contacts are provided on the main body of the image forming apparatus, and detection signals are transferred via these contacts. As is well known, this configuration may cause noise due to chattering between the contacts or malfunction due to poor contact between both contacts.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary developing device which eliminates the above-mentioned conventional drawbacks with a simple structure.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a rotary developing device of the type described at the beginning, in which means for transmitting a detection signal of a toner concentration sensor to the main body control section is configured to A light-emitting element that belongs to the developing device and emits light in response to a detection signal from the toner concentration sensor of each developing device, and a light-emitting element that is provided on the main body of the image forming apparatus and receives light from each light-emitting element and transmits the signal to the main body of the image forming apparatus. We propose a configuration that includes a light receiving element that outputs to the control section.

In this case, it is desirable to have one light-receiving element selectively paired with a plurality of light-emitting elements corresponding to the number of developing units and receiving light from the light-emitting elements.

[0012] Also, the plurality of light emitting elements are arranged at intervals in an annular groove formed in the developing device itself with the rotational axis of the developing device as the center, and the light receiving element projects into the annular groove. It is advantageous to configure.

[0013] Furthermore, it is particularly desirable that the annular groove is covered with a flexible sealing member, and that the light-receiving element projects into the annular groove through the sealing member.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a color copying machine having a rotary developing device 1. The rotary developing device 1 illustrated here has four developing units 2Y, 2M, 2C, and 2B. The developer chamber of each developing device is partitioned by a casing member 3, and a two-component developer 4Y of a different color is stored in each of the developer chambers.
, 4M, 4C, and 4B are accommodated. That is, the developer 4Y containing yellow toner and carrier is in the developing device 2Y.
However, the next developing device 2M contains developer 4M containing magenta toner and carrier, the next developing device 2C contains developer 4C containing cyan toner and carrier, and the other developing device 2B contains black toner. Developers 4B each having a carrier are accommodated therein. In the following explanation, each of these developing devices will be explained according to its toner color.
They may also be referred to as a yellow developer 2Y, a magenta developer 2M, a cyan developer 2C, and a black developer 2B.

As shown in FIGS. 2 and 3, the casing member 3 is supported by a rotating shaft 5 integrally fixed at its center, and each end of the rotating shaft 5 is shown in FIG. As shown, the image forming apparatus main body (in this example, the copying machine main body) 2
It is rotatably supported by a support plate 6 of 7. Further, the rotating shaft 5 is connected to a drive motor (not shown) via a transmission element such as a gear (not shown), and the operation of the motor causes one of the plurality of developing units 2Y, 2M, 2C, and 2B to be moved. One of them is brought to and positioned at a developing position opposite to a drum-shaped photoreceptor 7, which is a component of a latent image carrier. FIG. 1 shows a state in which the yellow developing device 2Y occupies the developing position. Instead of using the shaft 5 as a rotating shaft, it may be configured such that it is immovably supported on the main body of the image forming apparatus, and the rotary developing device is rotatably supported on this shaft and driven to rotate.

During the copying operation, the photoreceptor 7 is rotationally driven in a clockwise direction, and at this time, the surface of the photoreceptor is uniformly charged by the charger 8, and this charged surface is exposed imagewise as shown by arrow P, and the surface of the photoreceptor is An electrostatic latent image is formed for the first color image.

The first electrostatic latent image is visualized as a yellow toner image using yellow toner by the developing device that first occupies the developing position, in this example, the yellow developing device 2Y. This visible image is transferred by the action of a transfer charger 11 to a transfer paper 10 wrapped around a transfer belt (or transfer drum) 9 that is rotationally driven in the direction of arrow Q. The toner remaining on the photoconductor 7 after the transfer is cleaned by a cleaning device 12, and the surface of the photoconductor is subjected to a static eliminating action by a static eliminator 13.

Next, the photoreceptor 7 is charged again with the charger 8.
Subsequently, an electrostatic latent image for a second color image is formed by imagewise exposure, and this latent image passes through the rotary developing device 1. At this time, the developing device 1 is rotated by the aforementioned drive motor in a clockwise direction compared to the state shown in FIG. Therefore, the electrostatic latent image is visualized as a magenta toner image using magenta toner by the magenta developing device 2M, and this visible image is also transferred to the transfer paper 1 described above.
The yellow image is transferred onto the yellow image. The residual toner on the photoreceptor 7 is cleaned by a cleaning device 12, and then the surface of the photoreceptor is neutralized.

In exactly the same way, 3
The cyan developing device 2C and the black developing device 2B, which are sequentially brought to the developing position by the rotation of the rotary developing device 1, are used to form cyan toner and black toner, respectively. The images are visualized by , and these images are sequentially transferred onto the same transfer paper 10 .

The transfer paper 10 on which the visible images of four colors of toner have been superimposed is separated from the transfer belt 9 and passes through a fixing device (not shown), at which time the visible images are fixed and the transfer paper is ejected from the machine as full-color copy paper.

[0022] In some cases, visible images of toner of each color are sequentially transferred directly onto a transfer belt, and then the visible images are transferred onto transfer paper.

The yellow developing device 2Y shown in FIG. 1 includes a developing sleeve 14Y that is supported by the casing member 3 and is driven to rotate counterclockwise during the developing operation, and a developing sleeve 14Y that is installed inside the developing sleeve 14Y and fixed to the casing member 3. Magnet 15Y and
It has a paddle wheel 16Y that supplies the developer 4Y to the developing sleeve 14Y, and the developer 4Y supplied to the developing sleeve 14Y during the development operation is supported on the developing sleeve 14Y by the magnetic force of the magnet 15Y, and the developer 4Y is carried by the developing sleeve 14Y by the magnetic force of the magnet 15Y.
The developer is conveyed in the direction of rotation by the rotation of the developer, and excess developer is scraped off by the doctor blade 17Y. The toner in the developer 4Y conveyed to the development area between the developing sleeve 14Y and the photoconductor 7 electrostatically transfers to the electrostatic latent image formed on the photoconductor 7, converting the latent image into a visible image. become The configurations of the other developing units 2M, 2C, and 2B are the same as the yellow developing unit 2Y, and each element of these developing units 2M, 2C, and 2B includes the following:
M instead of the symbol Y given to each element of the yellow developing device 2Y
, C, and B, and their explanations will be omitted.

The number of developing devices need not be four as in the example of FIG. 1, but may be two or more. Further, the color of the toner of the two-component developer stored in each developing device is not limited to the example shown in FIG. 1, and for example, toner of red, blue, black, etc. may be stored. Alternatively, it is also possible to store toner of the same color, for example, black toner, and a developer containing a carrier in each developing device, and to use these in sequence. In addition, one developer chamber for each developer
Instead of forming one casing member 3, it is also possible to provide a casing member containing a two-component developer for each developing device, and to assemble these casing members integrally into one casing body to form a rotary developing device. can.

As described above, the rotary developing device can be configured in various ways, but in any case, the developing device has a plurality of developing devices containing a two-component developer, and is capable of forming an image. Rotatably supported by the apparatus main body, selectively bringing any one of the plurality of developing devices to a developing position facing the latent image carrier, using the two-component developer contained in the developing device, The electrostatic latent image formed on the latent image carrier is visualized as a toner.

By the way, while the rotary type developing device 1 is performing the developing operation, each of the developing units 2Y, 2M, 2C
, 2B are sequentially consumed, so the toner concentration decreases. Therefore, each developer has a toner concentration sensor 1 that detects the toner concentration of the two-component developer.
8Y, 18M, 18C, and 18B are provided. The toner concentration sensor shown here has a coil disposed in the developer circulation path in each developing device, and the inductance due to fluctuations in the toner to carrier ratio of the two-component developer flowing in this coil. This method detects the toner concentration using changes in the toner concentration, but there are other types of sensors, such as sensors that shine light on the two-component developer carried on each developing sleeve and use the reflectance to detect the toner concentration. Various sensors can be used.

Further, as shown in FIG.
1B, and on the other hand, as shown in FIG. 4, one light receiving element 22 that receives light from the light emitting element is provided at the tip of a protrusion protruding from the support plate 6 on the side of the image forming apparatus main body 27. is fixedly placed. These light emitting elements 2
Each toner concentration sensor 18Y, 18M, 18C, 1
The detection signal from 8B is transmitted to the main body control section 23, which is provided on the main body side of the image forming apparatus and is made up of, for example, a microcomputer.
(FIG. 5).

In this example, as shown in FIGS. 2 to 4, the device 1 is attached to the side wall of the casing member 3 of the rotary developing device 1.
An annular groove 24 is formed around the axis of rotation of the rotating shaft 5, that is, the axis X of the rotating shaft 5, and at the bottom of the annular groove 24,
, 2C, 2B, a plurality of light emitting elements 21Y, 21M corresponding to
, 21C, and 21B are fixedly arranged at intervals from each other. Then, the light receiving element 22 is connected to the annular groove 2 as shown in FIG.
4, the light receiving element 22 is configured to selectively pair with a plurality of light emitting elements and receive light from the light emitting elements. Each light emitting element 21Y, 21M, 21C, 21
B rotates together with the rotary developing device 1 when it rotates. Details of such action are as follows.

Here, as shown in FIG. 1, it is assumed that the yellow developing device 2Y is positioned at the developing position and is performing a developing operation. At this time, the toner concentration sensor 18Y provided in the developing device 2Y performs an operation of detecting the toner concentration of the two-component developer 4Y contained in the developing device.

The detection signal is amplified by an amplifier 19Y provided in the developing device 2Y, as shown in FIG. The amplified detection signal is input to a comparison/judgment device 20Y provided in the developing device 2Y, where it is compared with a preset reference value. That is, it is determined whether the toner concentration of the two-component developer 4Y is low or high, and when the toner concentration is lower than a predetermined concentration, the comparison/judgment device 20Y outputs an L signal (low level signal), which is used in the yellow developer. The light is input to the light emitting element 21Y belonging to 2Y, and the light emitting element 21Y emits light.

At this time, the light emitting element 21Y and the light receiving element 22 on the side of the image forming apparatus main body 27 form a pair facing each other as shown in FIG. Light enters the light receiving element 22. In this way, the light receiving element 22 receives light from the light emitting element 21Y,
The H signal output is input to the main body control section 23 provided in the image forming apparatus main body 27, and the control section 23 executes control to replenish toner to the yellow developing device 2Y whose toner concentration has decreased. That is, the rotary developing device 1 is provided with a toner case (not shown) that accommodates yellow toner, magenta toner, cyan toner, and black toner, respectively, corresponding to each developing device. A toner sending member (rotating body) is provided inside. Then, as described above, when a signal indicating that the toner concentration of the two-component developer 4Y stored in the yellow developing device 2Y has decreased is input from the light receiving element 22 to the main body control section 23, a signal from the control section 23 is input. In response to the command, the toner replenishment motor 26 (FIG. 5) provided on the image forming apparatus main body side rotates, thereby rotating the toner delivery member in the toner case containing yellow toner for a predetermined period of time.
Yellow toner is replenished from the toner case into the yellow developing device 2Y. The image forming apparatus main body 27 rotatably supports a drive gear (not shown) driven by the above-described toner replenishment motor 26, and a driven gear (also not shown) connected to each toner sending member of the developing device 1. ) is selectively engaged with the drive gear, and its delivery member is driven. That is, when a certain developing device, in the above example, the yellow developing device 2Y, occupies the developing area position, the driven gear belonging to that developing device is connected to the driving gear, and the driving force from the toner supply motor 26 is connected to the driving gear. A toner delivery member provided inside the toner case for yellow toner is driven via the driven gear. Such a configuration is well known and is described in detail in, for example, Japanese Patent Application No. 61-223211.

By replenishing the toner to the yellow developing device 2Y as described above, the toner concentration of the two-component developer 4Y is increased, thereby preventing a decrease in the image density of the visible image formed.

When the toner concentration of the two-component developer 4Y contained in the yellow developing device 2Y is higher than a predetermined concentration,
The comparator 20Y outputs an H signal (high level signal), which is input to the light emitting element 21Y. At this time, the light emitting element 21Y does not emit light because its input signal is the H signal, so the light receiving element 22 does not receive the signal, and the main body control unit 23
Outputs an L signal to. Therefore, the main body control section does not perform toner replenishment control as described above, and toner is not replenished into the yellow developing device 2Y.

In exactly the same way, when another developing device occupies the developing position and performs a developing operation, each of its toner concentration sensors 18M, 18C, or 18B detects the toner concentration of its respective two-component developer. The detection signal is amplified by an amplifier provided in each developing device, and is input to a comparison/judgment device also provided in each developing device, where it is compared with a reference value and detected in each developing device 2M, 2C. Alternatively, it is determined whether the toner concentration of the two-component developer stored in 2B is high or low. When the toner concentration is low, as described above, under the control of the main body control section 23, toner of each color is supplied to each developing device from the toner case belonging to each developing device by rotating the toner delivery member. be done. When the toner concentration is high, such toner replenishment operation is not performed. When each developing device 2M, 2C, 2B occupies the developing position, the light emitting element 21M,
21C and 21B form a pair facing the light receiving element 22, transmit and receive signals, and execute the above-mentioned control operation. The main body control unit 23 inputs the signal from the light receiving element 22 at the appropriate timing, determines which developing device the input is from the toner density sensor, and supplies a predetermined amount of toner to each developing device. Control to perform an action.

As mentioned above, each developing device 2Y, 2M, 2C
, 2B, the toner concentration sensors 18Y, 18M,
The detection signals from 18C and 18B are sent to the image forming apparatus main body 2.
The means for transmitting data to the main body control unit 23 on the side 7 includes light emitting elements 21Y, 21M, 21C, which belong to each developing device and emit light in response to a detection signal from a toner concentration sensor of each developing device.
21B, and a light receiving element 22 which is provided on the main body side of the image forming apparatus and receives light from each light emitting element and outputs the signal to the main body control part 23, and transfers the detection signal between the light emitting elements and the light receiving element 22. Since this is done via the light receiving element, the drawbacks of conventional methods using electric wires or contacts that slide against each other can be reliably avoided, and a stable signal can be transferred to the main body control section 23.

Further, in this example, the light emitting elements 21Y, 21M, 21C, and 21B belonging to each developing device are arranged in an annular groove 24 formed in the developing device itself, and the light receiving element 22 enters into this annular groove 24. Since each light emitting element and light receiving element are housed in the groove 24, it is possible to prevent dust such as toner from adhering to these elements, thereby preventing malfunctions over a long period of time. can be prevented from occurring.

In order to more reliably enhance the above-mentioned effect, the annular groove 24 is covered with a flexible sealing member 25 as shown in FIGS. It is desirable that the light receiving element 22 is fixed to the side wall surface and inserted into the annular groove 24 through an annular cut 25b formed in the seal member 25. Seal member 2
5 serves to actively prevent the problem of dust entering into the annular groove 24.

Further, the rotary developing device 1 is provided with a plurality of light emitting elements corresponding to the number of developing devices.
The main body of the image forming apparatus is only provided with one light-receiving element that selectively pairs with multiple light-emitting elements and receives light from the light-emitting elements. The cost can be reduced compared to the case where a plurality of light receiving elements are provided.

As shown in FIG. 5, the power source for toner concentration control, which is comprised of a toner concentration sensor, an amplifier, a comparator, etc. belonging to each developing device, is connected to the rotary developing device 1.
It may be provided on the side of the image forming apparatus main body 27, or may be provided on the side of the image forming apparatus main body 27.

Further, in the above embodiment, a comparator belonging to each developing device is provided on the side of the rotary developing device 1, and the detection signal (analog signal) from the toner density sensor is converted into a digital signal by the comparator. Although the on/off of light emission of the light emitting element is controlled accordingly, such a comparison/judgment device may be provided on the side of the main body of the image forming apparatus. In this case, each light emitting element emits light in response to an analog signal from each toner density sensor, this is received by the light receiving element, the output is compared with a reference value in a comparison/judgment device, and the output as a result of that judgment is given first. The information is input to the main body control section 23 in the same manner as in the embodiment.

The present invention can be widely applied to rotary developing devices in various image forming apparatuses other than electronic copying machines.

[0042]

According to the rotary developing device according to claim 1, since the detection signal of the toner concentration sensor is transferred to the main body control section via the light emitting element and the light receiving element, a stable signal can be reliably transferred. It is possible to prevent the occurrence of troubles caused by disconnection of electric wires, chattering between contacts, or poor contact as in the prior art.

According to the rotary developing device according to the second aspect, the number of light receiving elements can be reduced, the cost of the entire device can be reduced, and the structure can be simplified.

According to the rotary developing device according to the third aspect, since each light emitting element is arranged in the annular groove and the light receiving element projects into this groove, dust such as toner does not adhere to these elements. It is possible to suppress problems that cause malfunctions.

According to the rotary developing device according to the fourth aspect of the present invention, since the annular groove is covered with the sealing member, the above effect can be obtained more reliably.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus having a rotary developing device.

FIG. 2 is a partial perspective view of the rotary developing device.

FIG. 3 is a right side view of FIG. 2;

FIG. 4 is a sectional view showing the relationship between a light emitting element attached to the rotary developing device and a light receiving element provided on the main body side of the image forming apparatus.

FIG. 5 is a control block diagram of an embodiment of the present invention.

FIG. 6 is a view similar to FIG. 3, showing an embodiment in which the annular groove is covered with a sealing member.

FIG. 7 is an enlarged sectional view of the embodiment shown in FIG. 6;

[Explanation of symbols]

1 Rotary developing device 2Y developing device 2M developer 2C developer 2B Developing device 4Y Two-component developer 4M Two-component developer 4C Two-component developer 4B Two-component developer 18Y Toner concentration sensor 18M Toner concentration sensor 18C Toner concentration sensor 18B Toner concentration sensor 21Y Light emitting element 21M light emitting element 21C Light emitting element 21B Light emitting element 22 Photo receiving element 23 Main body control section 24 Annular groove 25 Seal member 27 Image forming device main body X axis

Claims (4)

[Claims] 1. A device comprising a plurality of developing devices containing a two-component developer, rotatably supported by an image forming apparatus main body, and selectively carrying a latent image on any one of the plurality of developing devices. In an image forming apparatus that visualizes an electrostatic latent image formed on a latent image carrier as a toner image using a two-component developer contained in the developing device. In the rotary developing device, each developing device has a toner concentration sensor that detects the toner concentration of the two-component developer, and a detection signal from the sensor is sent to a main body control section provided on the main body side of the image forming apparatus. In the rotary type developing device, the control unit controls replenishment of toner to the developing device whose toner concentration has decreased, and the means for transmitting the detection signal of the toner concentration sensor to the main body control unit is configured to transfer the detection signal of the toner concentration sensor to the main body control unit. A light-emitting element that is attached to the device and emits light in response to a detection signal from the toner density sensor of each developing device, and a light-emitting element that is provided on the image forming apparatus main body side and receives light from each light-emitting element and controls the main body by controlling the signal. 1. A rotary developing device characterized by having a light receiving element for outputting an output to a part. 2. The rotary type according to claim 1, further comprising one light-receiving element selectively paired with a plurality of light-emitting elements corresponding to the number of developing units and receiving light from the light-emitting elements. Developing device. 3. The plurality of light emitting elements are arranged at intervals in an annular groove formed in the developing device itself around the rotational axis of the developing device, and the light receiving element projects into the annular groove. 3. The rotary developing device according to 1 or 2. 4. The mold developing device according to claim 3, wherein the annular groove is covered with a flexible seal member, and the light receiving element projects into the annular groove through the seal member.