JPS5831579B2 - Tenshiyahoushikinogenkodaiidoogata - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer type electrophotographic copying machine with a moving document table or a moving optical system.

Conventionally, in the above-mentioned copying machines, the cleaning section is generally placed after the transfer section, and its structure is such that cleaning liquid (developer) is rubbed off with a blade while flowing over the residual image on the drum surface. In order to collect the cleaning liquid into the developing section, special piping is required between the cleaning section and the developing section, and special consideration is required in the design to prevent the cleaning liquid flowing down into the drum from wetting other parts of the drum. there were.

Generally, in the above-mentioned copying machines, as the speed of the copying process increases, it becomes possible to increase the copying speed.
When the speed of the copying process is increased, the mechanical condition of ensuring accurate reciprocation of the document table or optical system becomes a factor regulating the copying speed.
The speed ratio of double motion becomes close to 1:1.

Further, especially when a non-endless photosensitive drum is used, an unused portion of the outer periphery of the drum corresponding to the backward stroke increases, and it becomes impossible to increase the copying speed unless the drum diameter is increased.

Alternatively, during the backward movement, the drum must be temporarily stopped and the apparatus must wait until the document table or the optical system completes the backward movement, making the control of the machine complicated.

Also, in the case of one rotation/one copy, if the drum is not endless, the transfer paper will complete the transfer when one copy is completed, and the leading edge of the photoreceptor attached to the drum will be in front of the charging section, and the trailing edge will be in the transfer section. Since it has to be removed later, the area from the charging area on the outer periphery of the drum to the transfer area is wasted.

The present invention has been proposed in view of the various drawbacks mentioned above, and it simplifies the configuration of the cleaning system in an electrophotographic copying device, and eliminates unusable portions corresponding to the document table of the photosensitive drum or the backward stroke of the optical system. The purpose is to eliminate this problem and make the drum diameter more compact.

In other words, two revolutions of the photosensitive drum constitute one copy cycle, and before the drum surface after image transfer passes through a developing device, the residual charge on the drum surface is eliminated by a static eliminator, and the drum surface after static elimination is cleaned with a developer. It is characterized by the following.

An example will be described below in detail with reference to the drawing. The drawing shows an electronic copying machine with a moving document table type transfer system. 1 is a machine box, and on the top thereof is a document table 2 that moves forward in the right direction and back in the left direction. I'm getting lost.

0 is a document, which is located on the transparent portion 2.0 of the document table 2. When the document table 2 placed on the document table moves rightward at a speed synchronized with the circumferential speed of the photosensitive drum 3, a slit is exposed by the illumination lamp 5.degree.6 from below in the illumination section 4.

When the document table 2 completes its forward movement, it moves backward and returns to the illustrated position.

Elements of each process are arranged around the photosensitive drum 3,
The photosensitive drum 3 is first charged by the primary charger 1, and then exposed to an image projected by the optical systems 8 to 10 from the illumination unit 4, and at the same time is neutralized by the AC corona static eliminator 11 (or reversed polarity secondary charging). to form an electrostatic latent image.

Next, the latent image is fully exposed with a lamp 12 to increase the contrast, and then visualized with a liquid developing device 13. Subsequently, post-charging is performed with a charger 14, and a photosensitive drum is transferred with a paper feed roller 16 from a paper feed table 15. The charger 11 transfers the image onto the transfer paper P sent out toward the paper P with a bias bias.

After the transfer process, the transfer paper P is guided to the lower part of the dryer 19 by the separation and conveyance device 18, the transferred image is dried and fixed, and the paper P is discharged to the tray 20 outside the machine.

The liquid developing device 13 is configured to operate constantly during copying, and the developing device 21 is sent to the developing section 24 via a pipe 23 by a pump 22 inside the device, and overflowing developer 21 flows into a saucer 25 and passes through a pipe 26. It is configured to circulate back to the container.

Reference numeral 21 denotes a cleaning blade provided in the saucer 25, which is held by a support 28 and rotatably attached by a pin 29.

The photosensitive drum 3 has a photosensitive member 31 attached to the circumferential surface of the drum, and when the machine is stopped, the tip of the photosensitive member 31 is at Ll in the figure.
The rear end is set to be located at T1.

The document table 2 is at the position C6 in the figure when the machine is stopped, and when the machine starts, the drum 3 starts moving counterclockwise and the document table 2 simultaneously starts moving in the direction d (leftward) from C8 to C4. When the leading edge reaches the position L2 through the charging process, the original platen 2 reaches the position C1, and immediately the direction of movement is reversed and enters the forward stroke a to perform exposure.

Next, the tip of photoreceptor 3□ has finished developing, and the tip is L3.
When the blade 27, which had been in contact with the photoreceptor until then, is rotated clockwise in response to a signal from the main body of the machine, it is separated from the surface of the photoreceptor 31 so as not to disturb the image.

Photoreceptor 3. When the leading edge of the photoconductor goes through the transfer process and returns to the original position of Ll after exactly one rotation, the rear end of the photoconductor is at T1.
It is located at the position of , and is also receiving a -order charge.

Next, when the leading edge of the photoconductor 31 reaches L2 again, that is, when the rear end of the photoconductor 31 passes through the exposure simultaneous static elimination section 11 and reaches T2, the document table 2 reaches the position C2 and the exposure ends. Immediately, the direction of movement is reversed and the night shift begins.

At this time, the illumination lamps 5 and 6 are turned off, but the AC static eliminator 11 is kept in an operating state.

When the photoreceptor 31 passes through the static eliminator 11 again, an alternating current corona is applied to the surface of the photoreceptor 31 to eliminate the electric charge remaining on the surface.

Since the developing device 13 is operated while the main switch of the main body of the machine is turned on, when the surface of the photoreceptor whose residual charge has been removed reaches the developing section 24, it is washed with a developing solution and becomes clean.

When the leading end of the photoreceptor 31 reaches L3 and the rear end with the visible image reaches T3, a signal from the main body causes the blade 21 to
rotates counterclockwise, contacts the surface of the photoreceptor 31, wipes off the developer, and leaves the surface of the photoreceptor dry in preparation for the next copying process.

The photoconductor drum 3 further rotates and the rear end of the photoconductor 31 reaches T4.
When this is reached, the transfer of the visual image is completed and one copy is completed.
When the tip of the photoreceptor reaches Ll and completes two rotations, the machine stops, and at the same time, the document table 2 returns to the position C8 and stops.

When the photosensitive drum 3 completes two rotations, the photosensitive drum 3. The uncharged portions L2 to T1 are neutralized when passing through the static eliminator 11 in the next copy cycle and cleaned with a developer.

Further, the portions L2 to T2 to L3, which have already been neutralized, are similarly cleaned with the developer.

As described above, the present invention is configured such that one copy cycle is performed by rotating the photosensitive drum 302, and the surface of the photosensitive member after transfer is neutralized by the static eliminator 11, and then cleaned with a developer. (a) Electrophotography using the transfer method The cleaning system of a copying machine can have a simple configuration.

(b) Not only when an endless photosensitive drum is used, but also when it is impossible to create a special endless photosensitive drum, the outer diameter of the drum can be made compact by eliminating the unusable portion of the outer periphery of the drum that corresponds to the document table or the night shift process of the optical system. be able to.

(c) Since the drum of the document table needs to be kept constantly rotating even during the night shift operation of the optical system, the control of the entire machine becomes easy.

(d) In a document table or optical reciprocating type copying machine, the return movement time can be effectively used as cleaning time.

It has various effects such as.

Although the copying machine with a movable document table has been described above, it goes without saying that the present invention can also be applied to a copying machine with a movable optical system.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional side view of the present invention.

Claims (1)

[Scope of Claims] 1. The photosensitive drum is primarily charged, then the image of the original illuminated by a lamp is exposed, and at the same time the charge is removed by a static eliminator, the entire surface is exposed, and the obtained latent image is developed to form a visible image. Formed. In a transfer type document table moving type or optical system moving type electrophotographic copying machine that transfers this visible image onto transfer paper, two revolutions of the photosensitive drum constitute one copy cycle, and the latent image is transferred during the first revolution of the photosensitive drum. At the same time, during the second rotation of the photosensitive drum after the transfer of the visible image, the lamp is turned off and the residual charge on the photosensitive drum is erased by the static eliminator. Model or optical system moving type electrophotographic copying machine.