JPS63153560A - Color developing device - Google Patents

Abstract

PURPOSE:To effectively utilize a space on a developing unit in its radius direction by arranging plural sensors for executing color detection on the periphery of the developing unit. CONSTITUTION:Sensors P1-P3 corresponding to the number of developing sleeves are fixedly arranged around a copying machine body in parallel with each other in the circumferential direction around the developing unit 4 on the upstreamside of a developing position D in the rotational direction of the developing unit 4. On the other hand, doucers F1-F3 having different lengths in the circumferential direction of the unit 4 and arranged with equal intervals in the circumferential direction are formed unitedly with the unit 4. When the rotational center O of the developing unit 4, the rotational center O' of a developing sleeve S2 and the rotational center O'' of a photosensitive body 1 coincide with a line l at the time of rotating the unit 4 in order to select a developing color, the doucer F2 turns off the sensors P2, P3. Thereby, color detection and the detection of timing for executing the color detection can be executed only by the sensors P1-P3. Thus, the detecting constitution can be sharply simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a color developing device used in a color image forming apparatus.

In some types of color image forming apparatuses such as color copying machines and color printers, an electrostatic latent image that is color-separated from an original image is formed on a latent image carrier made of, for example, a photoreceptor. This electrostatic latent image is visualized using a developer of a predetermined color and transferred onto transfer paper, and this process is repeated for each different color to obtain a predetermined color image.

The above-mentioned image forming apparatus is generally called a full-color image forming apparatus, but on the other hand, an electrostatic latent image formed on a latent image carrier is selectively visualized using a developer of a different color. Monochrome image forming apparatuses that obtain monochrome or multicolor images desired by an operator are also known.

In such a color image forming apparatus, a developing unit is rotatably provided, and a plurality of developing devices that perform development using different color developers are arranged around the center of rotation of this developing unit, and these are moved to a developing position. A color developing device has been proposed.

In order to bring a predetermined developing device to the developing position, such a color developing device is provided with means for detecting which of the plurality of developing devices is placed at the developing position. Conventionally, as this type of means, a method has been proposed in which multiple sensors are arranged in the radial direction of the developing unit, but this conventional example requires the arrangement space occupied by the sensors in the radial direction. Therefore, it is difficult to arrange other equipment in this space, and the degree of freedom in terms of equipment layout is significantly hindered. In addition, in order to install and remove the developing unit in this axial direction, components such as sensors must be removed. I had to.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color developing device that eliminates the above-mentioned conventional drawbacks.

"In order to achieve the above object, the present invention relates to a color developing device according to the present invention, which includes a plurality of developing devices that are rotatably supported and that perform development using different color developers arranged around the center of rotation. a developing unit having a developing unit, a developing unit rotation driving means for rotationally driving the developing unit and moving each developing device to a developing position, a plurality of sensors arranged in parallel around the developing unit, and a developing unit that rotates integrally with the developing unit. The invention is characterized by comprising a detected member that turns on and off each of the sensors and changes the combination of on and off each time each developing device is placed at a developing position.

The present invention will be described below based on an embodiment in which the present invention is applied to a monochrome copying machine that obtains a visible image in a color desired by an operator.

In FIG. 1, an electrostatic latent image corresponding to an original image is formed on the surface of a drum-shaped photoreceptor 1, which is an example of a latent image carrier. The image is visualized with a developer, this visible image is transferred to transfer paper, and the transferred transfer paper is heat-fixed to obtain copy paper.

As shown in FIG. 3, a developing unit 4 is rotatably provided on both sides of the copying machine body. have. Here, assuming that the center of rotation of the developing unit 4, that is, the axis of the shaft 4A is O as shown in FIG. 1, each developing unit Di, D2, . D3 is placed. Further, on a concentric circle with respect to the rotation center O, developer carrying members configured as developing sleeves S1, S2, and 83, which are the main components of each developing device, are arranged at equal intervals in the circumferential direction. The developing unit 4 shown in FIG. 3 is rotatably supported by the case itself.

In addition, in FIG. 3, illustration of the developing sleeves SL and S3 is omitted to avoid clutter of the drawing.

A gear 8 is fixed to the shaft 4A of the developing unit 4, and in FIG. 1, the gear 8 is shown in a simplified manner overlapping the outline of the developing unit 4. As shown in FIG. 1, the gear 8 is rotated by the motor gear 6. as shown in FIG. They are driven in the direction of arrow a via gears 7, respectively. That is, the developing unit 4 is rotationally driven in that direction. The motor 5 and the gears 6, 7.8 constitute a developing unit rotation drive means in this example.

1 [As the unit 4 is rotationally driven, each developing sleeve SL, S2, 83 of each developing device rotates (revolutions) around the center O and is placed at a developing position corresponding to the photoreceptor 1. It will be destroyed.

Each developing sleeve 81. S2. Gear Gl is in S3.

G2. G3 are fixedly provided, respectively, and each of G3 is adapted to mesh with a sleeve drive gear 10 provided on the shaft of the photoreceptor l. Note that FIGS. 1 and 3 show each gear Gl, G2 . The figure shows a state in which the gear G2 of G3 is meshed with the sleeve drive gear 10. In this meshed state, the sleeve drive gear 10 rotates (rotates) the developing sleeve S2 via the gear G2. The other developing sleeves are rotated in exactly the same manner.

Each developer Di, D2. D3 includes the peripheral wall 40 of the unit 4.
Developers of different colors (-component or two-component developers) are housed in the developer chambers partitioned by the respective partition walls 41, 42, and 43.

These developers may be magnetic or non-magnetic, but for convenience, if we use magnetic developers, the developing sleeves SL, S2. Each magnetic developer is supplied to S3.

The electrostatic latent image on the photoreceptor 1 is developed into a visible image using a developer carried on its peripheral surface and carried on a developing sleeve of a developing device placed at a developing position.

By the way, in the past, since it was possible to change the color of the copied image by changing the color of the developer, it was possible to change the color of the copied image by preparing a plurality of developing units each having a different color of developer and replacing them. A developing device for obtaining a color copy image has also been used, but this has the drawback that it requires work to replace the developing means, and therefore, it takes a lot of time to copy.

Each developing sleeve SL, S2. After S3 supplies and carries different color developers, each developing sleeve is revolved around O, which is the rotation center of the developing unit, and positioned at the developing position, as shown in Fig. 1. In a developing device that performs development of different colors, there is no need to replace the developing means, so color images can be obtained in an extremely short copying cycle.

In a color developing device having such advantages, it is necessary to detect which developing sleeve is placed at the developing position. In other words, when the operator presses a color selection key (not shown) and rotates the developing unit in order to obtain a copy of the color he/she desires, the developing sleeve of the developing device containing the developer of the selected color It is necessary to detect that the developing device has been brought to the developing position, and to stop the developing sleeve of the developing device at the developing position based on this detection signal. This is the same in a full-color image forming apparatus, and when each developing device containing developer of each color including cyan, magenta, yellow, or black is brought to the developing position one after another, the developing sleeve of each developing device is It is necessary to detect that the position has been reached and stop it.

Hereinafter, the configuration for the above-mentioned detection and its effect will be explained.

In FIG. 1, the direction of rotation of the developing unit)
- With respect to the direction of mark a), there are sensors Pi in the upstream side of the developing device [D], and in the circumferential direction around the developing unit 4 (Fig. 3), the same number of sensors Pi as the developing sleeves; P2.
P3 are fixedly arranged side by side on the main body of the copying machine.

On the other hand, the developing unit 4 includes light shielding plates Fl having different lengths in the circumferential direction and arranged at equal intervals in the circumferential direction.

F2. F3 are each provided integrally.

When the developing unit is rotated in the direction of arrow a to select a developed color, the rotation center O of the developing unit, the rotation center 0' of the developing sleeve S2, and the rotation center O# of the photoreceptor 1 are on the line α. , the light shielding plate F2 is connected to the sensors P1 to P3.
Turn off sensor P2°F3.

Here, for example, well-known photocouplers are used as each of the sensors P1 to P3, and FIG. 2 shows what is seen from the direction of the arrow in FIG. 1. In this figure, the light from the light emitting element 11 is blocked by the light shielding plate F2, so that the light receiving element 12 is turned off. That is, the first
In the case of fig.

F3. Only the F2 sensor will be turned off.

When the gear G1 meshes with the sleeve drive gear 10 and the developing sleeve S1 is placed at the developing position, the light shielding plate F1 turns off only the sensor P3.

Further, when the gear G3 meshes with the sleeve drive gear 10 and the developing sleeve S3 is placed at the developing position, the light shielding plate F3 turns off all sensors.

The above relationships can be summarized in a table as follows.

Table 1 As can be understood from Table 1, since the combination of on and off is different for each developing sleeve, it is possible to determine which developing sleeve is in the developing position. That is,
When the operator depresses a color selection key to designate a developing color, it is possible to detect that the developing device containing developer of the designated color has reached the developing position. This will be referred to as color detection.

Light shielding plates Fl, F2. F3 constitutes an example of a detected member that rotates integrally with the developing unit to turn each sensor on and off, and changes the combination of on and off each time each developing sleeve is placed at the developing position. It is. In addition,
Depending on the configuration of the member to be detected and the type of sensor, the on/off status shown in Table 1 above can be reversed.

For example, as shown in Table 2 below.

According to the embodiment described above, since the sensors PI, P2 and P3 are arranged in the circumferential direction of the developing unit, they are arranged in the radial direction. Compared to the radial area, effective layout space can be secured in the radial area, and since the sensor is not placed in that area, it is easy to remove and install the developing unit in the axial direction. I can do it. Furthermore, each sensor PI, P2. By arranging P3 all together in the position shown in Figure 1, it is possible to secure effective space around the developing unit other than these sensors.
Also, the lead wires connected to each sensor can be routed together.

By the way, in Table 1 shown above, the sensor P3 located at the most downstream side in the rotational direction is off in all developing sleeves. That is, no matter which developing sleeve is placed at the developing position, sensor P3 is always turned off. On the other hand, in the case of Table 2, it is always turned on.

When the sensor P3 is turned off (in the case of Table 1) or turned on (in the case of Table 2), it is possible to detect that one of the developing sleeves is placed at the developing position. Therefore, when this is detected, the above-described color detection is performed to determine whether the developing sleeve of the selected developing device has reached the developing position at the timing of the detection signal. That is, when one of the sleeves reaches the developing position, the sensor P3 determines the timing at which color detection is performed to determine whether or not this sleeve is the selected one.
It can be determined by detecting the

From the above points, the sensors P1, P2, . Since this can be performed only by P3, there is no need for separate sensors for each detection, which greatly simplifies the detection configuration and also helps reduce costs.

In addition, each light shielding plate Fl, F2. Color detection is performed at the timing when F3 reaches sensor P3, and if the sleeve that has reached the development position is the sleeve of the selected developer, the development unit is stopped at that position.
If it is not the selected sleeve, the unit 4 continues to rotate.

At this time, color detection is not performed until the light shielding plate passes the sensor P3, and this light shielding plate passes the sensor PI, P3.
2. Erroneous detection can be prevented by preventing color detection from being performed again before exiting P3, and by performing color detection when the next light-shielding plate reaches sensor P3. This is the same when the rotation of the developing unit 4 is started.
Execution of color detection is prohibited until the light-shielding plate located at P3 removes these sensors, and when the next light-shielding plate reaches sensor P3, the color detection operation is executed.

When the selected sleeve reaches the developing position, the driving of the developing unit by the motor 5 is stopped and the unit is stopped at this position. A cam follower (not shown) may be engaged to ensure that the unit is stopped.

In the above-described embodiment, the number of sensors and the number of developing devices are made to match, but this is just an example, and it is not necessary to make them match. For example, as shown in Table 3 below, when three sensors PI, P2 and P3 are used, four types of detection are possible. Therefore, it is possible to detect that the developing sleeve has reached the developing position. Table 3
"1" indicates that each sensor is on, and "0" indicates off. Of course, when ``1j'' is turned off, ``0'' is turned on.

-1 In addition, if four sensors from Pl to P4 are used, it is possible to detect in eight ways and to detect that the developing sleeve has reached the developing position, as shown in Table 4 below. "1"
"0" is the same as in Table 3). Therefore, it is possible to detect a developing unit having up to eight developing devices.

Table 4 Table 3 and Table 4 also apply when the number of sensors is set to other numbers.
In the same way as above, the number that can be detected is determined.

In this way, the number of sensors can be appropriately set depending on the number of developing devices.

It is clear from Tables 3 and 4 that all the sensors on the most downstream side in the rotational direction of the developing unit 4 are turned on or off, regardless of the number of sensors.

According to the present invention, since a plurality of sensors for color detection are arranged side by side around the developing unit, the space in the radial direction can be effectively utilized. This increases the degree of freedom in equipment layout.

[Brief explanation of the drawing]

FIG. 1 is a schematic structural diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of a sensor included in the embodiment, and FIG. 3 is a cross-sectional view of the peripheral area of a developing unit. 4...Developing unit=16-D...Developing position DI, D2. D3...Developer PI, P2. P3...Sensor

Claims (1)

[Claims] A developing unit that is rotatably supported and has a plurality of developing devices that perform development using different color developers arranged around the center of rotation, and the developing unit is rotationally driven to move each developing device to a developing position. A developing unit rotation driving means, a plurality of sensors arranged around the developing unit, and rotating integrally with the developing unit to turn on and off each of the sensors, and this on/off combination is set for each developing unit. A color developing device comprising a detected member that changes each time the device is placed at a developing position.