JPS5852222B2 - Developer timing mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to drive control of a developing unit of an electrophotographic apparatus.

In conventional electrophotographic copying machines, if the developer is kept in continuous operation, the developer deteriorates due to fatigue, making it impossible to obtain a good copy image, or causing the developer to scatter into the machine. However, if it adheres to various parts of the equipment and contaminates it, or if it adheres to the electrical system, it may induce electrical leakage and cause an unexpected accident.

Furthermore, in a transfer type electrophotographic copying device, a large amount of developer stuck to the unexposed area of a transfer medium such as a drum is removed by a cleaning device and thrown away, so developer is wasted. become.

Even if a collection device is installed and the developer is collected again into the developer, once it has gone through the development and transfer process, the developer
This is undesirable as deterioration due to fatigue progresses.

Various methods have been taken to solve the above-mentioned problems, but the present invention provides an inexpensive and novel method and device for controlling the drive of a developing device that eliminates the above-mentioned problems. The purpose is to

The present invention starts the operation of the developing device based on the signal at the start of the optical system for exposure, the document table, or the document, detects the signal at the end of exposure, and from that point on, the distance from the exposure section to the development section corresponds to the distance from the exposure section to the development section. After the development is completed, the operation of the developing device is stopped, and the developing device is driven only for the time required for development.

However, in general, when delaying the time to drive the developing device as described above, an electrical delay circuit is formed and an electromagnetic clutch is used, but in the present invention, a spring clutch and a delay cam are used. It is characterized by being inexpensive and easy to use, and electrically does not require a delay circuit like the one described above, and uses a signal at the end of exposure to delay the end of development. .

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Here, a transfer type electrophotographic copying apparatus as shown in FIG. 1 will be described as an example.

In FIG. 1, a photosensitive drum 1 includes a photosensitive layer on a conductive support and a transparent insulating layer coated on the photosensitive layer, and rotates clockwise.

The photosensitive drum 1 is first charged by a primary charger 2,
Next, when it reaches the exposure section, the image of the document is exposed to slit light.
At the same time, AC static electricity is removed by the static eliminator 3.

Then, the entire surface is exposed by the lamp 4, and the photosensitive drum 1 is exposed to light.
An electrostatic latent image of the document image is formed on the surface of the original document, and then it reaches the developing section and is developed by the developing device 5.

Thereafter, the transfer paper P is charged by the post charger 6, subjected to pre-transfer processing, and then transferred from the paper feed section to the photosensitive drum 1.
The image on the photosensitive drum 1 is transferred onto the transfer paper P by the transfer charger 7, and then passes through the separation section 8 and is transferred to the fixing section 9.
The paper is guided to the paper discharge tray 10.

Thereafter, the remaining developer on the photosensitive drum 1 is wiped off by a cleaner 11, and the next copying cycle is repeated again.

If the developing device 5 is left in operation while the above-described cycle is repeated, there is a risk of the developer deteriorating and scattering as described above.

Therefore, when the document table 12 starts to move in the direction of arrow A for exposure, the cam 13 escapes, SW1 is activated, and the developing unit 5 starts to operate based on the signal.

Then, when the exposure is completed and the document table reaches the return position, that is, when the cam 14 operates SW2 at the position shown by the chain line, the signal is detected and the end of the developer operation is controlled. Bye.

Note that since the exposure area and the developing area on the photosensitive drum 1 are separated by an angle α, if the operation of the developing unit is extended for a time corresponding to the angle α and the developing unit is stopped, the developing unit can be operated only for the necessary time. , and remain stationary for other unnecessary periods of time.

Next, with reference to FIGS. 2, 3, 4, and 5, a delay mechanism for delaying the operation of the developing device by a time corresponding to the angle α will be explained.

When the document table 12 starts to move for exposure as described above, the cam 13 attached to the document table 12 escapes and SWl is activated.

Then, the signal causes the solenoid SL shown in Fig. 3 to
Attract the link 15 to the right and rotate the pin 16 and lever 17 counterclockwise.

Therefore, the pin 18 provided on the lever 17 pushes the lever 19 counterclockwise, and the claw 19 □ at the upper end of the lever moves away from the surface of the delay drum 210 that is free of the relay shaft 20 .

A lever 23 connected to the lever 17 by a spring 22 also rotates counterclockwise, and a claw 23 at the upper end of the lever 23 connects to the delay drum 2.
It falls into the notch 211 of 1.

At this time, the rotation of the sprocket 24 transmitted from the drive unit is transmitted to the relay shaft 20 through the spring 25 and driven ring 26 of the spring clutch, and the relay gear 27 and the developing device 1 drive gear 28
The signal is transmitted to the developer drive shaft 29 through the developer drive shaft 29, and the developer operates.

In the above state, the driven ring 26 is
The delay drum that is pressed down has claw 23□ and notch 2
Rotation is prevented by engagement of 1□.

The friction retaining ring 33 is composed of the retaining ring 33 which also serves as a container for storing the spring 31, and the spring receiver 30 fixed to the relay shaft 20 by a pin 32. It is slidable in the direction of the relay axis (see Figure 2).

Next, when the exposure is finished and the document glass reaches the return position, the first
When the cam 14 shown in the figure is in the position shown by the chain line, SW2 is activated, and the solenoid SL is released by the signal.

Then, as shown in FIG. 4, the lever 17 is pulled back by the spring 34, and the lever 23 is pushed by the pin 18 and rotates clockwise until the notch 21. Since the delay drum 21 comes off from the driven ring 2
6 and starts rotating in the direction of the arrow.

At this time, the claw 191 at the tip of the lever 19 is connected to the delay drum 210.
It is pressed against the surface by a spring 22.

While the delay drum 21 rotates in the direction of the arrow to the position shown in FIG. 5, the rotation from the drive section is transmitted to the developing device and the developing device is operating.

Then, another notch 212 provided in the delay drum 21
, the claw 19. at the tip of the lever 19. falls down and prevents the rotation of the delay drum 210, and at the same time the pawl 19 shown in FIG.
□ is the rough surface of the clutch outer ring 35 (fine claws are fine) 3
5. Press and act on this.

As a result, the clutch spring 25 becomes slack, cutting off the drive to the relay shaft 20, and the imager stops operating.

When the exposure start signal is input again, the solenoid SL attracts the link 15, the pawl 19 of the lever 19 disengages from the notch 212, and the clutch outer ring 35 is released, so that the relay shaft 20 rotates and operates the developing device.

The above cycle will be repeated.

At this time, the notch 212 on the delay drum and the claw 1 at that time
It is possible to delay the time after detecting the signal by the time corresponding to the angle β to the position 91.

In the above embodiment, the movement of the manuscript removal table was used as the signal generating means of the apparatus of the present invention, but in an electrophotographic copying apparatus in which the mirror or lens system moves, the movement of the mirror or lens system may be used as the signal generation means of the apparatus of the present invention. It is also possible to use it as a signal generating means of a device.

Furthermore, in a copying device in which only the document passes through a slit-shaped document illumination section, the movement of the document can be detected by a light source and a light receiving element, and this can be used as the signal generating means of the device of the present invention. be.

As described above, the present invention utilizes the movement stroke of a moving member of an electrophotographic copying apparatus as a signal generating means, and controls the drive of a developing unit by a mechanical clutch.

Since it is not necessary to form an electrical delay circuit according to the present invention, the developing device can be smoothly driven and controlled without being affected by temperature or humidity.

In addition, mechanical latches generally have a reliable effect with only a few parts, and are inexpensive, so they can be expected to operate reliably and reduce the number of manufactured items.

In other words, it is possible to eliminate the drawbacks of the prior art described above.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a simple structure of a transfer type electrophotographic copying apparatus, FIG. 2 is a sectional view of a mechanism according to the present invention, and FIGS. 3 to 5 are front views thereof. In the figure, 1 is a photosensitive drum, 5 is a developer, 12 is a document table, 13.14 is a cam, 15 is a link, 17.19, 2
3 is a lever, 19. ．． 231 is a claw, 20 is a relay shaft, 21
21 is a delay drum; 21 is a notch in the delay drum 21; 24 is a cutout in the delay drum 21;
25 is a sprocket, 25 is a spring clutch spring, 26 is a driven ring, 27 is a relay gear, 28 is a developer drive gear, 29 is a developer drive shaft, 33 is a friction holding ring, and 35 is a clutch outer ring.

Claims (1)

[Claims] 1. A moving member having a moving step necessary for image exposure related to electrophotographic image formation, means for detecting movement of the moving member, and detecting a movement start signal of the moving member with the detecting means. Mechanical power transmission means is provided for starting the developing device, detecting a signal indicating the end position of the moving member, and delaying the stoppage of the developing device by a predetermined time corresponding to the difference between the exposure position and the developing position on the photoreceptor. A developing device timing mechanism characterized by: