JPH087484B2 - Development device - Google Patents

Description

The present invention relates to a developing device used in an electrophotographic two-color color copying machine.

[Background of the Invention]

Conventionally, there is known one in which one image carrier, for example, a photoconductor drum of a copying machine, is provided with two types of developing devices at its peripheral portion to perform development. That is, for example, a developing device containing a red developer and a developing device containing a black developer are provided, and one of the developing devices is driven by a selection switching operation by an operator to perform a predetermined development. It is like this. The other developing device is retracted and in a non-developing state, and the two types of developing devices operate simultaneously and do not perform development at the same time.

The disclosures of Japanese Utility Model Application Laid-Open No. 60-39055 and Japanese Patent Application Laid-Open No. 62-15562 both aim to achieve the above object. Japanese Utility Model Laid-Open No. 60-39055 discloses that two developing devices can be integrally swung and one of the developing devices faces the image carrier by driving a pulse motor. Japanese Patent Laid-Open No. 62-15562 is provided with a link mechanism operated by a pulse motor so that any one of the developing devices faces the image carrier to perform development.

[Object of the Invention]

Switching between development and non-development in the two types of developing devices needs to be performed accurately, and the developing sleeve of the developing device that performs development must be driven in opposition to the image carrier with an accurate gap. Driving with a pulse motor regulates the positional relationship by the number of pulses emitted from the control unit,
In order to perform such control, it is necessary to maintain the component accuracy and the related dimensional accuracy of each part with high accuracy. However, performing such control for a device having a complicated configuration unnecessarily increases the cost.

The present invention is a developing device for two-color color, which is designed to perform necessary and sufficient functions without unnecessarily requiring a high degree of accuracy, and particularly, the switching of the developing devices to be operated is good and reliable. It is an object of the present invention to provide a developing device adapted to be carried out.

[Structure of Invention]

The above-mentioned object is to provide a plurality of developing devices in which a developing sleeve facing the photoconductor is pivotally supported by a frame of a copying machine so as to be close to the surface of the photoconductor, and a predetermined developing device among the plurality of developing devices. A designation means for selecting and designating one, a swinging means for swinging the developing sleeve of the developing device to a position for developing a latent image on the photoconductor, and a drive source provided in the main body of the copying machine, A drive gear that meshes with the gear of the developing sleeve of the developing device that is oscillated by the oscillating device and that rotates the gear, and a drive unit that is provided inside the copying machine body that drives the drive gear. The developing device designated by the designating means is brought close to the surface of the photoconductor, and the developing sleeve is swung by the swinging means until the developing position is reached. This drive gear meshes with the drive gear. In the developing device that rotates the gear of the designated developing device in accordance with the rotation, the designated developing device operates to develop the latent image formed on the photoconductor. If the developing device designated by the designating means does not reach the developing position for developing the photoconductor even after a lapse of a certain time after the operation is started, the driving gear is temporarily operated. Achieved by the device.

〔Example〕

 An embodiment of the present invention is shown in FIGS.

FIG. 1 shows an outline of the structure of a two-color color copying machine equipped with the developing device of the present invention. An original table glass 1 is provided on the upper surface of the main body of the copying machine, and an indicator, a ten-key, a color designation (development device selection) button, an exposure setting volume, a transfer paper size selection button, a photoconductor, etc. are provided on the front edge of the upper surface. An operation panel (not shown) is provided in which a copy start button for energizing the drive source of the entire rotating copier is arranged. A main switch that controls the initial operation of the copying process is provided on the side surface of the main body of the copying machine. When the document D is set on the surface of the platen glass 1 and the copy start button is operated, the exposure light source 3 relatively scans the document D so that the optical image of the document D includes the imaging lens 4a. It is guided to the surface of the photosensitive drum 2, which is an image carrier, via the exposure device 4.

The photosensitive drum 2 has selenium or
It is provided with a photoconductive layer such as OPC, and rotates in the direction of the arrow (clockwise) in conjunction with the above exposure scanning. In the peripheral portion of the photosensitive drum 2, a strip electrode 5, an exposure device 4, a two-color developing device 10 of the present invention, a transfer electrode 6, a separation device 7 including a separation electrode and a separation claw, a cleaning device 8, and an afterimage erasing device. 9 are sequentially arranged.

Before the light image arrives on the photosensitive drum 2, the photoconductive layer is positively and uniformly charged by the band electrode 5 to which a DC high voltage is applied, and the photoconductive layer in this state receives the light image. Then, the conductivity of the part that received the light becomes high and the charged electric charge of that part escapes to the metal cylinder, and the positive electric charge remains in the dark part according to the degree of light and dark. When an electrostatic latent image corresponding to the image of the original is formed on the surface of, the developing device 10 receives the developing action to form a toner image of a predetermined color.

2 shows details of the developing device 10, and FIG. 3 shows a cross section taken along the line AA of FIG.

The developing device 10 is composed of two developing devices 11A and 11B that are swingably mounted between two front and rear substrates 100A and 100B fixed to the main body of the copying machine.

That is, a developing device mounting frame 10B formed by integrally connecting a pair of front and rear plates 10A is rotatably supported between the substrates 100A and 100B via a pair of shafts 10C projecting from both side surfaces thereof. The two developing devices 11A and 11B are vertically attached to and fixed to the developing device mounting frame 10B.

The upper developing device 11A is, for example, red, while the lower developing device 1A is
1B, for example, stores each black developer, and includes well-known developing sleeves 111A and 111B at positions facing the peripheral surface of the photosensitive drum 2 on the left side of the shaft 10C, while the right side of the shaft 10C. And a biasing mechanism for elastically pressing and swinging each developing device at a position close to the end of the developing device.

The urging mechanism includes pressing plates 14A and 14B that settle by receiving the urging force caused by rotation of a cam member 13 described later, and the pressing plates 14A and 14B.
Each compression spring 15A, which biases the
15B, and a pair of them is provided near both side ends of each developing device via each support plate 16A and 16B into which the slide pins 17A and 17B that integrate the above-mentioned pressing plates are fitted.

On the other hand, the back of the substrate 100B rotates in both forward and reverse directions.
A DC series motor M is arranged and its rotation is on a shut 12 axially mounted between the substrates 100A and 100B via a worm W on the spindle and stepped gears G1 and G2 supported by shafts on the rear face of the substrate 100B. It is transmitted to the gear G3 after being decelerated.

That is, the rotation of the series motor M is caused by the worm W, the worm gear G1A of the stepped gear G1, and the stepped gear G1.
The small gear G1B and the large gear G2A of the stepped gear G2, the small gear G2B of the stepped gear G2, and the upper shaft 12 decelerated by the tooth number composition ratio of the gear G3 in the clockwise direction in FIG. The rotation of the series motor M and the reverse rotation of the series motor M can be counterclockwise.

The shaft 12 is a light-shielding plate 18 having a notch on the outer periphery between the gear G3 and the substrate 100B, and a pair of cam members described above at respective positions corresponding to the pressing plates 14A and 14B of the developing devices. It is equipped with the same angle phase as 13.

The cam member 13 is rotated by the operation of the series motor M, and the tip of the cam member 13 causes the pressing plate 14A or 1
4B is pressed to oscillate the developing device 10 about the shaft 10C by the reaction force of the compression spring 15A or 15B.
In other words, the rotation angle of the cam member 13, in other words, the swinging direction and the stop position of the developing device 10 are selected and controlled by the detection information from the detection member including the light shielding plate 18 and the photo sensor unit 19 provided so as to sandwich the light shielding plate 18. It has become.

That is, the light shielding plate 18 starts rotating clockwise from a position crossing the optical path of the light beam portion 19A of the photosensor unit 19 shown in FIG. 2, but the cam member is rotated at an angle at which the light beam portion 19A is opened. 13 is a pressing plate 1 of the developing device 11B
The cam member 13 is set to have an angular relationship such that the cam member 13 presses the pressing plate 14A of the developing device 11A at an angle at which the light beam portion 19A is shielded again.

Therefore, FIG. 2 shows a state in which the cam member 13 is in the neutral original position. The developing device 11A, 11B is in a state in which none of the developing devices 11A and 11B is pressed by the cam member 13.
Although 10 also shows that it is in the neutral position, it is urged clockwise by a relatively small moment due to its own structure due to its structure.

Further, in the developing device of the present invention, the rotating shafts of the developing sleeves 111A and 111B are projected to the back surface of the plate 10A and the gears G5A and G5B are fixed to the rotating shafts,
The developing device 11A also rotates about the shaft 10C as a fulcrum when the developing device 11B is pressed by the cam member 13, and one of the gears G5A or G5B is used for the swinging motion of the developing device 10 with the shaft 10C as a fulcrum. Is engaged with a drive gear G4 connected to the drive system of the copying machine body.

Further, as is well known, since each developing device is configured to rotate the stirring members 112A and 112B in association with each developing sleeve, when the gear G5A or G5B meshes with the drive gear G4 and the clutch is connected. As a result of the power of the drive system of the copying machine main body being transmitted to the developing device 11A or 11B, the stirring member 112A or 112B
As a result, each two-component developer is uniformly stirred and the toner is negatively charged. Also, the upper developer 11A
With respect to the red toner consumed by the developing process, the red toner contained in the hopper 113A drops into the upper developing device 11A by the rotation of the replenishment screw 114A, and the red toner is replenished. The same applies to the lower developing device 11B,
The hopper 113B containing black toner is located on the front side of the device and toner is being replenished.
B and the supply screw 114B are not shown.

The developing units 11A and 11B face the peripheral surface of the photosensitive drum 2 by the following process according to the color of the toner image selected when the electrostatic latent image formed on the photosensitive drum 2 is visualized. The switch is set to the position to be used.

FIG. 4 shows a control circuit of a drive system provided in the main body of the copying machine for operating each of the developing devices 11A and 11B. The operation will be described below with reference to FIG. 5, in which each developing device is selected. The state set at the developing position is shown in FIGS. 6 and 7.

After the original is placed on the original placing portion of the copying machine, and the color designation button is pressed in advance before operating the copy start button, the detection member necessary for swinging the developing device designated by the control portion to the developing position. ON / OFF signal information for “open” and “closed” is input in advance and the series motor M is turned clockwise (C
W) starts rotating. Next, the copy start button is operated.
At this time, when the color designation button is not pressed and the copy start button is operated, it is designated that the specific developing device (lower developing device 11B) is located at the developing position of the photoconductor.

When the developing device containing the black developer, that is, the lower developing device 11B is designated by the color designation button, for example, one signal of "open" is input to the control unit as the developing device selection information, and the light shielding is performed. The rotation of the series motor M is stopped at the angle at which the plate 18 fully opens the light beam portion 19A of the photo sensor unit 19 as shown in FIG. When the rotation is stopped, the brake is applied on a circuit basis and the rotation is correctly stopped at a preset stop position.

At this time, the cam member 13 is moved to the lower developing device 11B as shown in the drawing.
As a result, the developing device 10 is swung in the clockwise direction with the shaft 10C as a fulcrum, and the developing sleeve 111B of the developing device 11B has a predetermined gap with the peripheral surface of the photosensitive drum 2. The gear G5B is engaged with the drive gear G4 at the same time.

Therefore, if the copy start button has already been pressed at this point, the drive gear G4 also rotates following the rotation of the photosensitive drum 2 due to the start of the drive source of the main body of the copying machine that drives the photosensitive drum 2, the paper feed mechanism and the like. Then, the development of the electrostatic latent image on the photosensitive drum 2 with the black developer is started.

To prevent the driving gear G4 and the gear G5A or the driving gear G4 and the gear G5B from meshing with each other when the tooth tips collide with each other and do not mesh, use a toothed gear with a toothed tip. ing.

Nevertheless, when the gear G5B cannot mesh with the drive gear G4 due to the collision of the tooth tips, the developing device 10 cannot swing to the required angle. Therefore, the position setting with respect to the photosensitive drum 2 and the gear G5B are not performed. Since power transmission will not be realized, in the present invention, in such a state, the drive gear G4 is temporarily driven and rotated to promote the meshing with the gear G5B.

That is, when the swinging of the developing device 10 is insufficient, the pressing plate 14B causes the end portion of the slide pin 17B to abut against the wall surface 120B of the developing device 11B before being pressed by the cam member 13, so that the pressing member 14B together with the cam member 13 is used. The light shielding plate 18 cannot rotate to the angle at which the light beam 19A is released.

Therefore, if the "open" signal is not obtained by the detection member even after a predetermined set time b has elapsed since the series motor M was started, the drive gear G4 is automatically and temporarily controlled to be driven and rotated. As a result, the engagement of the gear G5B with the drive gear G4 can be realized very early and reliably. It should be noted that the set time b is from the start of the series motor M in the case of normal operation to the cam member 13
Is a time (for example, 1.1 seconds) obtained by adding a slight margin to the time required to completely push the pressing plate 14B.

When the developing device containing the red developer, that is, the upper developing device 11A is designated, for example, two signals of "open" and "closed" are input to the control unit as the developing device selection information. Then, as shown in FIG. 7, the light shielding plate 18 stops the rotation of the series motor M at the angle where the light beam portion 19A of the photo sensor unit 19 is once opened and then closed again from the neutral position.

At this time, the cam member 13 is at an angle at which the pressing plate 14A of the upper developing device 11A is pushed down as shown in FIG.
0 is pivoted counterclockwise around the shaft 10C as a fulcrum to set the developing sleeve 111A of the developing device 11A to a position keeping a predetermined gap with the peripheral surface of the photosensitive drum 2, and at the same time mesh the gear G5A with the drive gear G4. Then, the development of the electrostatic latent image on the photosensitive drum 2 with the red developer is started by the same process as in the case of the developing device 11B described above.

Further, the developing device 11A is used and the gear G5A is the drive gear G4.
When not engaged with the cam member 13, the pressing plate 14A brings the end of the slide pin 17A into contact with the wall surface 120A of the developing device 11A before being completely pressed by the cam member 13.
Along with the light shield plate 18, the light beam portion is again provided as shown in FIG.
It is in a state where it cannot rotate to the angle that shields 19A.

Therefore, when the series motor M is started and a predetermined set time “a” has passed and, for example, two signals of “open” and “closed” are not obtained, the drive gear G4 is automatically driven and temporarily rotated. You can do it. The set time a
Is the time required from the start of the series motor M to the time when the cam member 13 completely pushes the pressing plate 14A in the case of normal operation, with some margin added.

Thus, either the upper developing device 11A or the lower developing device 11B is set at the developing position and driven by power transmission, and the portion of the photosensitive drum 2 on which the electrostatic latent image is formed is the upper developing device 11A. Developing sleeve 111A or lower developing device 1
When reaching the portion of the developing sleeve 111B of 1B, the red toner or the black toner having a negative charge is electrostatically adsorbed by the remaining positively charged portion on the surface of the photosensitive drum 2, and as a result, the surface of the photosensitive drum 2 is attracted. Forms a red toner image or a black toner image corresponding to the electrostatic latent image.

On the other hand, the transfer paper P in the cassette 21 selected by the transfer paper size selection button is sent out by the paper feed roller 22 at a timing such that the front end of the transfer paper P coincides with the front end of the toner image, and the transfer paper P thus sent out. The toner image on the surface of the photosensitive drum 2 is transferred by the transfer electrode 6 to which a DC voltage is applied.

After that, the transfer paper P is separated from the photosensitive drum 2 by a separating device 7 including a separating pole and a separating claw to which an AC high voltage is applied, and is conveyed to a fixing device (not shown) by a conveyor belt 23 to fix a toner image, and recording is performed. It is discharged to a tray provided outside the device. Further, after the toner image is transferred onto the transfer paper P, the residual toner remaining on the peripheral surface of the photosensitive drum 2 is cleaned by the cleaning device 8 and the potential on the photosensitive drum 2 is kept below a certain level by the residual image erasing device 9. It is dropped and the next copy operation is ready.

When the copying is completed and the drive of the drive source of the copying machine main body is stopped to stop the rotation of the photosensitive drum 2, the series motor M starts to rotate in the reverse direction to move the cam member 13 and the light shielding plate 18 in the counterclockwise direction (CCW). ) And the cam member 13 stops at the neutral position. Thus, the developing device 10 is returned to its initial position, that is, the neutral position shown in FIG.
Power transmission to G4 is cut off.

If a jam occurs during copying, the rotation of the photosensitive drum 2 is automatically stopped by the jam detection signal, the series motor M is rotated in the reverse direction, and the cam member is operated in the same manner as at the end of copying described above. 13 is returned to the neutral position, and accordingly, the developing device 10 is also returned to the neutral position, and both developing units 11A and 11B are stopped in the non-developing state.

〔The invention's effect〕

In the developing device of the present invention, each developing device can be arbitrarily selected by operating the color designating button, and can be elastically pressed to a set position with respect to the image carrier, and the power of the developing device can be changed. Since the connection is made at the same time and the switching operation is made surely, it is possible to make the structure extremely simple without requiring high precision for the constituent members. As a result, it is possible to provide a developing device for a two-color color copying machine that can reliably switch the functions by a simple operation at a low price.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a main part of a two-color color copying machine equipped with the developing device of the present invention. 2 and 6 and 7 are explanatory views of respective states of the developing device. FIG. 3 is a sectional view taken along the line AA of FIG. FIG. 4 is a control circuit diagram of the developing device. FIG. 5 is a flowchart of the control circuit. 2 ... Photosensitive drum, 10 ... Developing device 11A, 11B ... Developing device, 13 ... Cam member 14A, 14B ... Press plate, 15A, 15B ... Compression spring 18 ... Shading plate 19 ... Photo sensor unit 111A, 111B …… Developing sleeve G5A, G4B …… (Developer side) Gear G4 …… Drive gear M …… Series motor

Claims (1)

[Claims] 1. A plurality of developing devices, each of which has a developing sleeve facing a photoconductor and is swingably supported by a frame of a copying machine so as to be close to a surface of the photoconductor, and a predetermined one of the plurality of developing devices. Designating means for selectively designating one developing device, swinging means for swinging the developing sleeve of the developing device to a position for developing a latent image on a photoconductor, and the swinging means swinging by the swinging means. A drive gear provided in the main body of the copying machine for meshing with a gear of a developing sleeve of the developing device and rotating the gear; and a drive means provided in the main body of the copying machine for driving the drive gear, The developing unit designated by the designating unit is brought close to the surface of the photoconductor, and the developing sleeve is swung by the swinging unit until the developing position is reached. At this developing position, the gear of the developing sleeve and the drive gear are Mesh with each other, In the developing device for developing the latent image formed on the photosensitive member by rotating the gear of the developing sleeve of the designated developing device, the designated developing device designates the latent image formed on the photoconductor. Detecting means for detecting that the developed developing device has moved to a developing position for developing a latent image on the photoconductor by the swinging means, and the designating means even if a predetermined time has elapsed after the swinging means started operation. When the detecting unit does not detect that the developing unit designated by the above has moved to the developing position for developing the photoconductor, the control unit controls the drive gear to temporarily operate. Developing device.