JPH03256069A - Image forming device - Google Patents

Abstract

PURPOSE:To suppress a noise and a vibration caused by the high-speed movement of a mobile table attached to a developing unit by changing the home position of a developing device according to a color mode, and shortening the moving distance of developing unit at a developing stage. CONSTITUTION:Magenta 1M, cyan 1C, yellow, and black developing units 1Y, and 1BK are mounted on the mobile table 1 of a horizontally mobile type developing device. On the other hand, a home position sensor 2, and first, second, and third home position flags 3, 4, and 5 are attached to the black side of the mobile table 1. Then, the home position is changed so that the moving distance of the developing unit is shortened according to a set color mode. Thus, the noise and vibration caused by the high-speed movement of the mobile table 1 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. The present invention relates to an image forming apparatus that develops a latent image formed on an image bearing member using a plurality of developing devices, and particularly relates to an image forming apparatus in which a plurality of developing devices are mounted on a movable body and moved to a developing position. The present invention relates to an image forming apparatus.

An electrophotographic color printer will be described as an example of a conventional image forming apparatus. This color printer is usually equipped with developing devices for four colors: magenta, cyan, yellow and black. These developing devices are placed on a moving table, and by moving the moving table, the developing devices for the required color can be applied. The latent image formed on the photoreceptor drum is developed by being brought close to the photoreceptor drum.

The cross-sectional structure of a conventional image forming apparatus of this type is shown in FIG. 12.As shown in FIG.
, IBK are arranged at equal intervals on the moving table l, and the moving motor 17
The movable table 1 is moved from side to side in the figure via a gear mechanism (not shown). When a developing device of a required color comes directly below the photosensitive drum 8, development of that color is performed according to instructions from the control circuit. In addition, each color developer LM, 1C1
A pulse motor is used as the moving motor 17 to move IY and IBK accurately and quickly below the photosensitive drum. Furthermore, since a reference position is required to accurately move each color developer directly below the photoreceptor drum, a home position sensor 2 is provided around the moving stage 1, and the home position sensor 2 is set at the home position. A flag 3, such as a light shielding plate, is attached to the movable base 1, for example, to change the output of the light. Using this home position as a reference point, the developing units IM, IC1IY, and IBK of each color are
The positioning of the movable stage 1 is controlled by driving the moving motor 17 at a rotational speed corresponding to the distance required to move the movable stage 1 directly below the photosensitive drum.

However, in the conventional apparatus with the above configuration, there is only one home position, so for example, when the color mode is set to yellow single color or black single color, etc., the development of the latent image on the photoreceptor drum is difficult. It was necessary to move the moving table all at once at high speed in order to meet the deadline, which caused printer noise and vibration.

Therefore, an object of the present invention is to change the home position so that the moving distance of the developing device is shortened according to the set color mode, to suppress noise and vibration caused by high-speed movement of the moving table as much as possible, and to reduce the noise and vibration of the motor driver. An object of the present invention is to provide an image forming apparatus that reduces heat generation.

The above objects are achieved by an image forming apparatus according to the present invention. To summarize, the present invention provides a developing device comprising a plurality of developing devices and a movable body on which the plurality of developing devices is mounted, the movable body being moved by a driving means to perform development of a predetermined color, and the developing device. The image forming apparatus includes means for setting a plurality of home positions for the apparatus and moving the developing device to a predetermined home position in advance according to the setting of a color mode.

According to a preferred embodiment of the present invention, the home position of the developing device is located between each developing device or directly below each developing device, and the home position movement operation of the developing device due to the color mode setting is performed when the color mode is set. or when the start switch is pressed.

EMBODIMENT OF THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a first embodiment in which the present invention is applied to an electrophotographic color printer.

As usual, a magenta developer IM, a cyan developer 1c, a yellow developer IY, and a black developer IBK are mounted on the movable table 1 of the horizontally movable developing device.

Furthermore, a home position sensor 2, a first home position flag 3, a second home position flag 4, and a third home position flag 5 are attached to the back side of the moving table 1.

Next, the entire sequence of this color printer will be explained using a full color mode as an example. Normally, the developing device is equipped with a home position sensor 2 as shown in FIG.
is stopped with the first home position flag 3 blocking light. At this time, when the color mode is set to full color using the operation unit 6 and the start switch 7 is pressed, the photoreceptor drum 8 and transfer drum 9 begin to rotate under the control of the printer control circuit 31, and the photoreceptor drum is activated by the charger 10. The surface is uniformly charged. Next, a document (not shown) is scanned while being irradiated with the document illumination lamp 11, and the reflected light at that time is guided to the lens system 14 via the first mirror 12 and the folding mirror 13, and is imaged on the color image sensor 15. Image exposure is performed with laser light E modulated by a magenta image signal color-separated by the color image sensor 15, and an electrostatic latent image is formed on the photoreceptor drum 8. Then, the pulse motor 17 is rotated by a drive signal from the motor driver 16, and the developing device is moved in the direction of the arrow ■ via a drive system (not shown) so that the magenta developing device IM is positioned directly below the photosensitive drum 8. let However, as it is, the distance between the photoreceptor drum 8 and the magenta developer IM is too wide and normal development will not occur.
Simultaneously with the movement of the developing device, the magenta developing device IM is brought close to the photosensitive drum 8 by a push-up mechanism (not shown), and then development is performed. On the other hand, the transfer paper that has advanced via the paper feed guide 18 and the registration rollers 19 is electrostatically wound around the transfer drum 9 by the action of the attraction charger 20 and the contact roller 21 in synchronization with a predetermined timing. .

The transfer drum 9 rotates in the direction of the arrow shown in the figure in synchronization with the photosensitive drum 8, and the developed image developed by the magenta developer IM is transferred to the transfer paper wrapped around the transfer drum 9 by the transfer charger 22. . The transfer drum 9 continues to rotate and prepares for transfer of the next color (cyan in FIG. 1).

On the other hand, the photosensitive drum 8 is neutralized by the charger 23, cleaned by the cleaning member 24, charged again by the charger 10, and then exposed to the laser beam E modulated by the next cyan image signal. During this time, the developing device is horizontally moved in the direction of the arrow (■) opposite to that for magenta. Perform the development.

Subsequently, the above process is performed for yellow and black, respectively, and when the transfer of the four colors is completed, the four-color developed image on the transfer paper is charged by each charger 25 and 26, and
Next, the developed image on the transfer paper is recharged by the charger 27,
The transfer paper is separated from the transfer drum 9 by the separation claw 28 and sent to the fixing device 30 by the conveyor belt 29. Thus,
The full color print sequence is completed and the desired full color print image is formed.

Next, the home position movement operation according to various color mode settings according to the present invention will be explained with reference to the flowchart shown in FIG.

First, in Sl, the color modes are magenta single color, cyan single color, blue color, green, red, 3 color (magenta, cyan, yellow), and full color (magenta,
(cyan, yellow, black),
The developing device remains at the normal home position (first home position) shown in Figure 2 and is not moved (S2).
.

When the start switch 7 is pressed (S6), the developing devices necessary for each color mode are moved to predetermined positions, and a series of copying operations as described above are performed (S7 to
S9) An image of the desired color is created and the operation ends.

Next, when the color mode is set to single yellow in Sl, the pulse motor is rotated at low speed (S
3) When the developing device is moved and the second home position flag 4 blocks light from the home position sensor 2 as shown in FIG. 3, the pulse motor is stopped (S4, S5);
The developing device stops at the position shown in FIG. That is, in this case, the second home position becomes the reference point of the developing device. When the start switch 7 is pressed (S6), the developer required for the color mode (in this case, the yellow developer IY) is moved to a predetermined position based on this second home position, and the developer described above is moved to a predetermined position. A series of copying operations as described above are performed (S7 to S9) to create an image of the desired color, and the operation ends.

Next, when the color mode is set to monochromatic black in Sl, the pulse motor is rotated at a low speed (S
3) When the developing device is moved and the third home position flag 5 blocks light from the home position sensor 2 as shown in FIG. 4, the pulse motor is stopped (S4, S5);
The developing device stops at the position shown in FIG. That is, in this case, the third home position becomes the reference point of the developing device. Then, when the start switch 7 is pressed (S6), the third home position is used as a reference for the developing device necessary for the color mode (in this case, the black developing device IBK).
) is moved to a predetermined position, a series of copying operations as described above are performed (S7 to S9), an image of the desired color is created, and the operation ends. Note that when the color mode is set to yellow single color, in the above example, the developing device is
Although the developing device was moved to the home position, there is no problem even if the developing device is moved to the third home position as in the case of black monochrome, since the moving distance of the developing device during development is the same.

FIG. 6 is a circuit configuration diagram of the motor driver 16 that controls the movement of the developing device described above. It detects a signal indicating whether the button is pressed or not, and sends a drive signal to the motor drive section 602 to perform operations such as driving the pulse motor 17. Such circuits are well known in the art and will not be described in detail.

In the first embodiment described above, the movement of the developing device to the home position is started immediately when the color mode is set, but the movement of the developing device to the home position is started as soon as the start switch is pressed. You can do it like this. A flowchart explaining the operation of this second embodiment is shown in FIG. As is clear from the figure, in this embodiment, the color mode setting step (S1) is followed by the start switch-on step (S2), and the pulse motor stop step (S2) follows the color mode setting step (S1).
6) is followed by a document reading step (S7), but since the other points are the same as in the first embodiment, a description thereof will be omitted.

In each of the above embodiments, the first home position flag 3 is located between the magenta developer LM and the cyan developer IC, and the first home position flag 3 is located between the magenta developer LM and the cyan developer IC.
A home position flag 4 was placed between the cyan developer IC and the yellow developer 1Y, and a third home position flag 5 was placed between the yellow developer IY and the black developer IBK. Therefore, each developer is moved directly below the photoreceptor drum 8 and then brought closer to the photoreceptor drum 8 by a push-up mechanism (not shown) to perform a predetermined developing operation. In this embodiment, one home position flag is added, and each flag is placed directly below each color developer, as shown in FIG. As a result, the number of times the developer is moved during a copying operation can be reduced by one. The first home position in this embodiment is as shown in FIG.
This is the position where the first home position flag 801 shields the home position sensor 2 from light, and this position is also the normal home position of the developing device.

In this third embodiment, when the color mode is set to magenta single color, blue red, three color (magenta, cyan, yellow), and full color (magenta, cyan, yellow, black), the developing device The normal home position (first home position) shown in FIG. 8 remains and no moving operation is performed. When the start switch 7 is pressed, the magenta developing device IM is moved closer to the photosensitive drum 8 by a push-up mechanism (not shown) at this position, and a series of copying operations as described above are performed. In the case of blue-red, three-color, and full-color other than magenta single color, the developer of a predetermined color is moved directly below the photoreceptor drum 8 according to the set color mode, and is brought closer to the photoreceptor drum and placed in a series. A copying operation is performed, an image of the desired color is created, and the operation ends.

Next, when the color mode is set to cyan single color or green, the pulse motor is rotated at low speed to move the developing device, and as shown in FIG. 9, the second home position flag 802 is set to the home position sensor. The pulse motor is stopped at the time when the light is blocked from light, and the developing device is stopped at the position shown in FIG. That is, in this case, the second home position becomes the reference point of the developing device. When the start switch 7 is pressed, the cyan developer IC is brought close to the photosensitive drum 8 by a push-up mechanism (not shown) at this second home position without moving, and the above-described series of copying operations is performed. It is done. When green is set, the yellow developer IY is moved directly below the photoreceptor drum 8 after the cyan developer IC using the second home position as a reference point, and is brought close to the photoreceptor drum to form a series of A copying operation is performed, a green image is created, and the operation ends.

Next, when the color mode is set to yellow single color, the pulse motor is rotated at low speed to move the developing device, and the third home position flag 803 is set to the home position sensor 2 as shown in FIG. When the light is blocked, the pulse motor is stopped and the developing device is stopped at the position shown in FIG. That is, in this case, the third home position becomes the reference point of the developing device. and start switch 7
When is pressed, the yellow developer IY is brought closer to the photosensitive drum 8 by a push-up mechanism (not shown) at this third home position without moving, and the above-described series of copying operations are performed to produce a yellow image. image is created and the operation ends.

Next, when the color mode is set to black monochrome, the pulse motor is rotated at low speed to move the developing device, and the fourth home position flag 804 is set to the home position sensor 2 as shown in FIG. When the light is blocked, the pulse motor is stopped and the developing device is stopped at the position shown in FIG. 11. That is, in this case, the fourth home position becomes the reference point of the developing device. and start switch 7
When is pressed, the black developer IBK is brought close to the photosensitive drum 8 by a push-up mechanism (not shown) at this fourth home position without moving, and the above-described series of copying operations are performed to produce a black color. An image of
The operation ends.

Thus, the third embodiment has the advantage that the number of times the developer is moved during the copying operation can be reduced by one compared to the first and second embodiments.

In each of the above embodiments, the present invention was applied to an electrophotographic color printer, but the present invention is not limited to electrophotography, but can also be applied to an electrostatic recording color printer. It can also be applied to image forming apparatuses other than printers.

As explained above, the image forming apparatus according to the present invention changes the home position of the developing device according to the set color mode and shortens the moving distance of the developing device during the developing stage. This has remarkable effects such as being able to suppress as much as possible the noise and vibration caused by high-speed movement of the moving table on which the developing unit is attached, and also reducing the heat generated by the motor driver.

FIG. 7 is a flowchart illustrating the home position moving operation of the second embodiment of the image forming apparatus according to the present invention.

FIGS. 8 to 11 show the third image forming apparatus according to the present invention.
FIG. 3 is a schematic cross-sectional view showing the home position of the developing device in the embodiment.

FIG. 12 is a schematic cross-sectional view showing an example of a conventional image forming apparatus.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a first embodiment in which the present invention is applied to an electrophotographic color printer. 2 to 4 are schematic cross-sectional views showing the home position of the developing device in the first embodiment. FIG. 5 is a flowchart illustrating the home position movement operation of the first embodiment. FIG. 6 is a circuit diagram of a motor driver for moving the developing device. 1: Moving table 1M: Magenta developer IC = Cyan developer 1Y: Yellow developer IBK Ni Black developer 2: Home position sensor 3.801: First home position flag 4.802:
2nd home position flag 5.803: 3rd home position flag 7: Start switch 8; Photosensitive drum 16: Motor driver 17: Pulse motor 804: 4th home position flag

Claims (1)

[Scope of Claims] 1) A developing device comprising a plurality of developing devices and a movable body on which the plurality of developing devices are mounted, the movable body being moved by a driving means to develop a predetermined color; and the developing device. Set multiple home positions for the device,
An image forming apparatus comprising: means for moving the developing device to a predetermined home position in advance according to a color mode setting. 2) The image forming apparatus according to claim 1, wherein the home position is located between each developing device or directly below each developing device. 3) The image forming apparatus according to claim 1, wherein the home position movement operation of the developing device according to the color mode setting is performed at the time when the color mode is set or when a start switch is pressed.