JP3045409B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a plurality of developing devices each containing a two-component developer and rotatably supported by an image forming apparatus main body. The electrostatic latent image formed on the latent image carrier is selectively brought to a developing position facing the latent image carrier, and the two-component developer contained in the developing device is used to form a visible image as a toner image. The present invention relates to an image forming apparatus that includes a rotary developing device that transmits a detection signal of a sensor of each developing unit to a main body control unit provided on the main body of the image forming apparatus and controls the control unit.

[0002]

2. Description of the Related Art In an image forming apparatus of the above type configured as an electronic copying machine, a printer, a facsimile, or the like, any one of the rotary developing devices has
The electrostatic latent image formed on the latent image carrier, which is selectively positioned at the developing position, is visualized. Each developing device contains a two-component developer having toners of different colors from each other, and forms a color visible image by using them, or uses a plurality of developing devices having the same color toner. Form a visible image of the same color.

[0003] Such a rotary developing device is disclosed in Japanese Utility Model Laid-Open No. 58-146251, Japanese Utility Model Laid-Open No. 59-4549, Japanese Patent Application Laid-Open No. 60-257559, Japanese Patent Application No. 61-1987.
No. 2,232,111.

[0004] While each developing unit performs the developing operation as described above, the toner of the two-component developer is sequentially consumed. Therefore, each developing unit is provided with a toner concentration sensor, and the sensor is used to control the inside of each developing unit. The toner concentration of the developer is detected, a detection signal is transferred to a main body control unit provided on the image forming apparatus main body side, and toner is supplied to the developing device whose toner concentration is reduced by the control of the control unit. I have.

As described 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, as such transfer means, generally, an electric wire is used. Used. That is, each toner density sensor and the main body control unit are connected by an electric wire, and the detection signal of the sensor is transferred to the main body control unit.

However, since the rotary developing device rotates as the name suggests and selectively brings each developing device to the developing position, the toner density sensor of the rotating developing device and the stationary main body control unit are connected by electric wires. When connected, the rotation of the developing device may cause the electric wire to be twisted and cut.

Although it is possible to fix the central shaft of the rotary developing device and pass an electric wire through the central shaft, the shaft may not be fixed in some cases, and its use range is limited.

Further, the rotary developing device is provided with a contact connected to each toner density sensor, and a contact which is in sliding contact with the contact is provided on the image forming apparatus main body side, and a detection signal is transferred via these contacts. It is also known that, according to this configuration, noise due to chattering between the contacts and malfunction due to poor contact between the two contacts may occur.

[0009]

SUMMARY OF THE INVENTION The present invention has been made based on the above-described novel recognition, and an object of the present invention is to reliably transfer a detection signal of a sensor to a main body control unit. It is an object of the present invention to provide an image forming apparatus capable of suppressing the occurrence of troubles due to disconnection of electric wires, chattering between contacts, or poor contact.

[0010]

According to the present invention, in order to achieve the above object, in an image forming apparatus of the type described at the beginning, a means for transferring the detection signal to the main body control unit is provided.
A light emitting element which is provided corresponding to each developing device of the rotary developing device and emits light in accordance with a detection signal of a sensor of each developing device; And a light receiving element for receiving the light from the main body and outputting the signal to the main body control unit. The plurality of light emitting elements are arranged in an annular groove formed in the developing device around the rotation axis of the rotary developing device. An image forming apparatus is provided, wherein the annular groove is covered by a flexible seal member, and the light receiving element protrudes into the annular groove through the seal member.

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

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus configured as a color copying machine having a rotary developing device 1. The rotary developing device 1 illustrated here has four developing units 2.
Y, 2M, 2C, and 2B. The developer chambers of the respective developing units are partitioned by a casing member 3, and contain two-component developers 4Y, 4M, 4C, and 4B having different colors, respectively. That is, the developer 4Y having the yellow toner and the carrier is in the developing device 2Y, the developer 4M having the magenta toner and the carrier is in the next developing device 2M, and the developer having the cyan toner and the carrier is further in the next developing device 2C. 4C, and a developer 4B having a black toner and a carrier are accommodated in another developing unit 2B, respectively. In the following description, each of these developing units is associated with the color of the toner,
Y, a magenta developing device 2M, a cyan developing device 2C, and a black developing device 2B may be called.

As shown in FIGS. 2 and 3, the casing member 3 is supported by a rotating shaft 5 integrally fixed to the center thereof, and each end of the rotating shaft 5 has only one end in FIG. As shown in the figure, the image forming apparatus main body (the copying machine main body in this example) 2
7 rotatably supported by a support plate 6. 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 any one of the developing devices 2Y, 2M, 2C, and 2B to operate. One of them is brought to a developing position opposed to a drum-shaped photoconductor 7 which is a configuration of the latent image carrier, and is positioned. FIG. 1 shows a state where the yellow developing device 2Y occupies the developing position. Instead of using the shaft 5 as a rotating shaft, the shaft 5 may be fixedly supported by the image forming apparatus main body, and the rotary type developing device may be rotatably supported by the shaft and driven to rotate.

During the copying operation, the photosensitive member 7 is driven to rotate clockwise. At this time, the surface of the photosensitive member is uniformly charged by the charging charger 8, and the charged surface is image-exposed as indicated by an arrow P. Then, an electrostatic latent image for a first color image is formed.

The first electrostatic latent image is visualized as a yellow toner image with a yellow toner by a developing device which first occupies the developing position, in this example, a yellow developing device 2Y. The visible image is transferred to a transfer paper 10 wound around a transfer belt (or transfer drum) 9 driven to rotate in the direction of arrow Q by the action of a transfer charger 11.
The toner remaining on the photoconductor 7 after the transfer is cleaned by the cleaning device 12, and the surface of the photoconductor is subjected to a charge removing operation by the charge remover 13.

Next, the photosensitive member 7 is again charged with the charging charger 8.
The electrostatic latent image for the second color image is formed by image exposure, and the latent image passes through the rotary developing device 1. At this time, the developing device 1 is rotated clockwise by the above-described drive motor from the state shown in FIG. 1, and the magenta developing device 2M occupies the developing position facing the photosensitive member 7. Therefore, the electrostatic latent image is visualized as a magenta toner image with magenta toner by the magenta developing device 2M, and the visible image is also transferred to the transfer paper 1 described above.
On the yellow image, the image is transferred in a superimposed manner.
The residual toner on the photoconductor 7 is cleaned by the cleaning device 12, and then the surface of the photoconductor is neutralized.

In the same manner, the third
And an electrostatic latent image for an image of the fourth color is formed, and the cyan developing device 2C and the black developing device 2B sequentially brought to the developing position by the rotation of the rotary developing device 1 respectively provide a cyan toner and a black toner. And these are sequentially transferred to the same transfer paper 10.

The transfer paper 10 on which the visible images of the four colors of toner are transferred in an overlapping manner is separated from the transfer belt 9 and then passes through a fixing device (not shown). Is discharged out of the machine as full color copy paper.

In some cases, a visible image of each color toner is sequentially transferred directly to a transfer belt, and then the visible image is transferred to transfer paper.

The yellow developing device 2Y shown in FIG. 1 is supported by the casing member 3 and is driven to rotate counterclockwise during the developing operation thereof. The developing sleeve 14Y is provided inside and fixed to the casing member 3. A magnet 15Y,
The developing sleeve 14Y has a paddle wheel 16Y for supplying the developer 4Y to the developing sleeve 14Y. The developer 4Y supplied to the developing sleeve 14Y during the developing operation is carried on the developing sleeve 14Y by the magnetic force of the magnet 15Y.
The excess developer is conveyed in the rotational direction by the rotation of, and the excess developer is scraped off by the doctor blade 17Y. The toner in the developer 4Y conveyed to the developing area between the developing sleeve 14Y and the photoconductor 7 is electrostatically transferred to an electrostatic latent image formed on the photoconductor 7, and the latent image is converted into a visible image. Become The configurations of the other developing units 2M, 2C, and 2B are the same as those of the yellow developing unit 2Y, and each element of these developing units 2M, 2C, and 2B includes:
M, C, and B are attached to the components of the yellow developing device 2Y instead of the reference symbol Y, and the description is omitted.

The number of developing units need not be four as in the example of FIG. 1, but may be two or more. Also, the color of the toner of the two-component developer contained in each developing device is not limited to the example of FIG. 1, and for example, toner such as red, blue, and black may be contained. Alternatively, a developer having a toner of the same color, for example, a black toner and a carrier, may be stored in each developing device, and these may be used sequentially. Further, instead of forming the developer chamber of each developing device by one casing member 3, a casing member accommodating a two-component developer is provided for each developing device, and these are integrally assembled to one casing main body. To form a rotary developing device.

As described above, the image forming apparatus of the present embodiment has a plurality of developing devices containing two-component developers and is rotatably supported by the image forming device main body. One of them is selectively brought to a developing position facing the latent image carrier, and the electrostatic latent image formed on the latent image carrier is converted into a toner image using the two-component developer contained in the developing device. And a rotary developing device for visualizing the image.

While the rotary developing device 1 is performing the developing operation, the developing devices 2Y, 2M, 2
Since the toners in the developers C and 2B are sequentially consumed, the toner density decreases. Therefore, each developing device is provided with a toner concentration sensor 18Y, 18M, 18C, 18B for detecting the toner concentration of the two-component developer. The toner concentration sensor shown here has a coil disposed in the circulation path of the developer in each developing unit, and the inductance accompanying the fluctuation of the ratio of the toner and the carrier of the two-component developer flowing in the coil. It detects the toner density using the change, but other types of sensors, such as a sensor that irradiates the two-component developer carried on each developing sleeve and detects the toner density using the reflectance, are used. Can be used. The image forming apparatus of the present embodiment transfers the detection signal of the sensor of each developing unit to a main body control unit provided on the main body side of the image forming apparatus, and performs predetermined control by the control unit, as exemplified below. It is configured to perform.

As shown in FIG. 3, each of the developing devices 2Y, 2M, 2C, 2B has a light emitting element 21Y, 21M, 21C, 2C.
1B, on the other hand, a light receiving element 22 for receiving light from the light emitting element is provided at the tip of a projection protruding from the support plate 6 on the image forming apparatus main body 27 side as shown in FIG. Are immovably arranged. These light emitting elements 2
Each of the toner density sensors 18Y, 18M, 18C, 1 is connected to the respective toner density sensors 18Y, 21M, 21C or 21B and the light receiving element 22.
The detection signal of 8B is transferred to the main body control unit 23 (FIG. 5) provided on the main body side of the image forming apparatus and formed of, for example, a microcomputer.

In this embodiment, as shown in FIGS. 2 to 4, the side wall of the casing member 3 of the rotary type developing device 1
, That is, an annular groove 24 centered on the axis X of the rotating shaft 5, and the developing device 2Y, 2
M, 2C, and 2B corresponding to the light emitting elements 21Y, 21M,
21C and 21B are fixedly arranged at an interval from each other. Then, as shown in FIG.
, And the light receiving element 22 is configured to selectively form a pair with the plurality of light emitting elements and receive light from the light emitting elements. Each light emitting element 21Y, 21M, 21C, 21B
When the rotary developing device 1 rotates, the rotary developing device 1 rotates integrally therewith. Details of such an operation are as follows.

Here, it is assumed that the yellow developing device 2Y is positioned at the developing position and performs the developing operation as shown in FIG. At this time, the toner concentration sensor 18Y provided in the developing device 2Y performs a toner concentration detecting operation of the two-component developer 4Y stored 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 / determination unit 20Y provided in the developing device 2Y, where it is compared with a preset reference value. That is, it is determined whether the toner density of the two-component developer 4Y is low or high. When the toner density is lower than the predetermined density, the comparator 20Y outputs an L signal (low level signal), which is a yellow developer. The light is input to the light emitting element 21Y attached to 2Y, and the light emitting element 21Y emits light.

At this time, the light emitting element 21Y is opposed to the light receiving element 22 on the image forming apparatus main body 27 side as shown in FIG. Light enters the light receiving element 22. Thus, the light receiving element 22 receives the light from the light emitting element 21Y,
The output of the H signal is input to a main body control unit 23 provided in the image forming apparatus main body 27, and the control unit 23 executes control for supplying toner to the yellow developing device 2Y having a reduced toner density. That is, the rotary developing device 1 is provided with a toner case (not shown) that accommodates a yellow toner, a magenta toner, a cyan toner, and a black toner, respectively, corresponding to each developing device. A toner delivery member (rotary body) is provided inside. 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 unit 23, the control unit 23 In response to the command, the toner supply motor 26 (FIG. 5) provided on the image forming apparatus main body side rotates, whereby the toner delivery member in the toner case containing the yellow toner is rotationally driven for a predetermined time.
Yellow toner is supplied from the toner case into the yellow developing device 2Y. A drive gear (not shown) driven by the above-described toner supply motor 26 is rotatably supported by the image forming apparatus main body 27, and a driven gear (also not shown) connected to each toner delivery member of the developing device 1. ) Selectively engages with the drive gear, and the delivery member is driven. That is, when a certain developing device, such as the yellow developing device 2Y in the above example, occupies the developing area, the driven gear of the developing device is connected to the driving gear, and the driving force from the toner supply motor 26 is applied to the driving gear and the driven gear. , The toner delivery member provided inside the yellow toner case is driven. Such a configuration is well known in the art, and is described in detail in, for example, Japanese Patent Application No. 61-223211.

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

When the toner density of the two-component developer 4Y stored in the yellow developing unit 2Y is higher than a predetermined density,
The comparison / determination unit 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 an H signal, and thus the light receiving element 22 does not receive the signal,
3 to output an L signal. Therefore, the main body control unit does not perform the toner supply control as described above, and the toner is not supplied to the yellow developing device 2Y.

Similarly, when another developing device occupies the developing position and performs the developing operation, each of the toner concentration sensors 18M, 18C or 18B detects the toner concentration of the two-component developer. Then, the detection signal is amplified by an amplifier provided in each developing device, and is input to a comparison judging device similarly provided in each developing device, where it is compared with a reference value, and is compared with each of the developing devices 2M and 2C. Alternatively, it is determined whether the toner concentration of the two-component developer contained in 2B is high or low. When the toner concentration is low, as described above, the toner of each color is supplied to each developing device from the toner case corresponding to each developing device by the rotation of the toner delivery member under the control of the main body control unit 23. Is done. When the toner density is high, the toner supply operation is not performed. When each of the developing units 2M, 2C, and 2B occupies the developing position, its light emitting element 21M, 21
C and 21B form a pair facing the light receiving element 22, transmit and receive signals, and execute the above-described control operation. The main body control unit 23 inputs the signal from the light receiving element 22 at a certain time, determines which of the developing units is the input from the toner density sensor, and performs a predetermined toner replenishing operation for each of the developing units. Control to do. The control section controls the toner supply to the developing device having the lowered toner concentration.

As described above, in the image forming apparatus of this embodiment, the means for transferring the detection signal of the sensor of each developing unit to the main body control unit is provided corresponding to each developing unit of the rotary developing device. A light-emitting element that emits light in response to a detection signal of a sensor of each developing unit, and a light-emitting element that is fixed to the image forming apparatus main body and receives light from each light-emitting element and outputs the signal to the main body control unit. A light receiving element. According to this configuration, since the detection signal is transmitted through the light emitting element and the light receiving element, the drawbacks caused by using the electric wires and the contacts that are in sliding contact with each other can be reliably prevented, and the stable signal can be controlled by the main body control. Can be transferred to the unit 23.

In the image forming apparatus of this embodiment, the light emitting elements 21Y, 21M, 21C,
21B is arranged in an annular groove 24 formed in the developing device itself, and the light receiving element 22 is configured to protrude into the annular groove 24 to exchange signals. A plurality of light emitting elements are arranged at intervals in an annular groove formed in the rotary developing device around the rotation axis of the developing device, and a light receiving element protrudes into the annular groove. As described above, since each light emitting element and each light receiving element are housed in the groove 24, it is possible to prevent dust such as toner from adhering to these elements, and to prevent a malfunction from occurring for a long time.

Further, as shown in FIGS. 6 and 7, the annular groove 24 is covered with a flexible sealing member 25 (not shown in FIGS. 2 to 4), and the proximal end portion 25 of the sealing member 25 is formed.
a is fixed to the side wall surface of the rotary developing device 1 and an annular cut 25 formed in the seal member 25.
The light receiving element 22 protrudes into the annular groove 24 through b.
The light receiving element 22 protrudes into the annular groove through the seal member 25. With this configuration, it is possible to more reliably prevent dust from entering the annular groove 24.

In the image forming apparatus of this embodiment, a plurality of light emitting elements corresponding to the number of the developing devices are provided in the rotary type developing device 1, but a plurality of light emitting elements are provided in the image forming apparatus main body. Only one light receiving element is provided which selectively forms a pair with the light emitting element and receives light from the light emitting element. The image forming apparatus has one light receiving element that selectively forms a pair with a plurality of light emitting elements corresponding to the number of developing units of the rotary developing device and receives light from the light emitting elements. Therefore, the cost can be reduced as compared with the case where a plurality of light receiving elements corresponding to each light emitting element are provided.

As shown in FIG. 5, a power supply for controlling the toner concentration, which is composed of a toner concentration sensor, an amplifier, a comparator and the like provided in each developing device, is provided on the rotary developing device 1 side. Alternatively, it may be provided on the image forming apparatus main body 27 side.

In the above-described embodiment, a comparison / judgment unit corresponding to each developing unit is provided on the side of the rotary developing device 1, and a detection signal (analog signal) from the toner density sensor is converted into a digital signal by the comparison / judgment unit. The on / off control of the light emission of the light emitting element is controlled according to this, but such a comparison / determination unit may be provided on the image forming apparatus main body side. In this case, each light emitting element emits light in accordance with an analog signal from each toner density sensor, and this is received by the light receiving element, and its output is compared with a reference value in a comparison / determination unit, and the output as a result of the determination is obtained. The data is input to the main body control unit 23 in the same manner as in the previous embodiment.

The present invention can be widely applied to various image forming apparatuses other than the electronic copying machine.

[0040]

According to the first aspect of the present invention, since the detection signal of the sensor is transferred to the main body control section via the light emitting element and the light receiving element, a stable signal can be transferred without fail. It is possible to prevent disconnection of the electric wire and occurrence of troubles due to chattering or poor contact between the contacts. In addition, since each light emitting element is arranged in the annular groove, the annular groove is covered by the sealing member, and the light receiving element protrudes into the annular groove through the sealing member, so that dust such as toner adheres to these elements. A malfunction that causes a malfunction can be suppressed.

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

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating 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 cross-sectional view showing a relationship between a light emitting element attached to the rotary developing device and a light receiving element provided on the image forming apparatus main body side.

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

FIG. 6 is a view similar to FIG. 3, showing a state where the annular groove is covered with a sealing member.

FIG. 7 is an enlarged cross-sectional view illustrating a state in which the light receiving element protrudes into the annular groove through the sealing member.

[Explanation of symbols]

 1 rotary developing device 2Y developing device 2M developing device 2C developing device 2B developing device 4Y two-component developer 4M two-component developer 4C two-component developer 4B two-component developer 18Y sensor 18M sensor 18C sensor 18B sensor 21Y Light Emitting Element 21M Light Emitting Element 21C Light Emitting Element 21B Light Emitting Element 22 Light Receiving Element 23 Main Body Control Unit 24 Annular Groove 25 Seal Member 27 Image Forming Apparatus Main Body X Axis

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/08 G03G 15/01 G03G 15/00 303

Claims (2)

(57) [Claims] 1. A have a plurality of developing devices containing a two-component developer is rotatably supported by the image forming apparatus main body,
One of the plurality of developing devices is selectively brought to a developing position facing the latent image carrier, and formed on the latent image carrier using the two-component developer contained in the developing device. A rotary type developing device that visualizes the electrostatic latent image as a toner image, and transfers a detection signal of a sensor of each developing unit to a main body control unit provided on the image forming apparatus main body side; Means for transferring the detection signal to the main body control unit in each of the rotary developing devices .
Each developing unit provided corresponding and the light emission element you emitting respectively in accordance with the detection signal of the sensor of each of the developing devices, are fixedly arranged in the image forming apparatus main body side, and the light from the light emitting element receiving, and a light receiving element and outputs the signal to the main control unit, about the rotation axis of the rotary type developing device
The plurality of light emitting elements in an annular groove formed in the developing device.
And the annular groove is provided with a flexible seal.
The light receiving element is covered by a member, and the light receiving element passes through the seal member.
An image forming apparatus which projects into the annular groove . 2. The image forming apparatus according to claim 1, further comprising one light receiving element selectively forming a pair with a plurality of light emitting elements corresponding to the number of the developing devices and receiving light from the light emitting elements. apparatus.