JPS615272A - Image forming device - Google Patents

Abstract

PURPOSE:To clean a photosensitive drum completely by rotating the photosensitive drum for a prescribed time while bringing a cleaning blade into contact with the photosensitive drum after an electrostatic latent image on the photosensitive drum is transferred and separating the blade from the photosensitive drum thereafter and separating a developing roll after the contacting end face passes the area of the developing roll. CONSTITUTION:A photosensitive drum 1 is rotated in the direction of an arrow to electrostatically charge primarily it by an electrifier 2. An optical image 3 is made incident from an original omitted in the figure to form a latent image, and this image is developed by a developing device 6, and the developed image is transferred to a transfer paper 8, and this paper 8 is fed to a fixing device omitted in the figure. An unnecessary toner remains on the photosensitive drum 1, and a cleaning blade 10 is brought into contact with the photosensitive drum 1; and in this state, the photosensitive drum 1 is idled to removed the toner. The blade 10 is separated after a prescribed time, and the developing drum 6 is brought into contact with the photosensitive drum 1 until the contacting end face passes the contacting area of the drum 6, and the drum 6 is separated after the contacting end face passes there. Thus, the remaining toner is swept completely to enter into the next copying process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic method and apparatus for performing an electrophotographic process in a transfer electrophotographic apparatus. Generally, in the electrophotographic process, a two-layer photoreceptor consisting of a photoconductive layer and a conductive substrate is charged with positive or negative polarity, and then imagewise exposed to form an electrostatic latent image, which is then subjected to a development process to become visible. A method for obtaining an image, a positive polarity (the photoconductive layer is a Nil
ξ of the semiconductor) or negative polarity (when the photoconductive layer is a P-semiconductor) - charging is performed, followed by image exposure and alternating current charging or secondary charging with the opposite polarity to the primary charging to eliminate the primary charge. There is a method in which an electrostatic latent image is formed, the contrast of #[ is increased by full-surface exposure, and then a visible image is obtained through the phenomenon process. Figure 1 illustrates the latter process, where 1 is a photoreceptor that rotates in the direction of the arrow, 2 is a DC corona discharger that performs primary charging, 3 is an optical image, and 4 is a corona discharger that performs secondary charging. 5 is the entire surface exposure source, 6
is 3J! #7 is a transfer charger that transfers the visible image to the transfer paper 8 by corona discharge with the same polarity as the primary charge. After transfer, the photoconductor is used again. In order to do this, the toner remaining on the photoreceptor is removed by the cleaning M material 10.However, the toner removed by the cleaning member 10 accumulates and adheres near the cleaning member, which adversely affects the next pattern forming process. There is.

In particular, when the developing device used in the electrophotographic process is a liquid type in which toner is dispersed in a carrier liquid, the following drawbacks occur.

(i.e. when the electrophotographic device is stopped or the photoreceptor is stopped)
The cleaning solution accumulates on the cleaning member 10 (cleaning blade) and the surface of the photoconductor that it comes into contact with, and the cleaning solution dries during the rest period, causing the toner in the solution to dry. yo Dry toner is difficult to remove from the photoreceptor. Therefore, when the photoreceptor is rotated to start the electrophotographic process next time, due to poor cleaning of that area, there will be defects or stains, and good image formation cannot be expected.

As stated in Patent Publication No. 31453 of 1975, the cleaning blade is cleaned by supplying a liquid to the cleaning blade with a pump before starting the process, or by providing a sponge moistened with iA cleaning liquid to the cleaning blade. The above drawbacks were eliminated by moistening the contact area between the photoreceptor and the photoreceptor.

However, due to the use of pumps, sponges, etc., the structure becomes complicated, and the contact portion between the blade and the photoreceptor during rest cannot be completely cleaned.

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an image forming apparatus with less image staining.Another object of the present invention is to provide an image forming apparatus having a process sequence for obtaining high quality images from the beginning. Another object of the present invention is to provide an image formatting apparatus having an improved post-processing sponge after the process is completed.

In this first embodiment, the cleaning means, which had been left off during the pause, is brought into contact with the surface of the rotating body to which the liquid has been applied, before the latent image is formed, and the means for applying the liquid is activated. After a predetermined period of time: The no-jung means is activated.

As a result, the surface of the rotating body can be wetted, the friction between the cleaning means and the rotating body can be reduced, and the rotating body can rotate smoothly. Further, it is possible to form a latent image after the cleaning means has rotated for a predetermined period of time after the cleaning means is activated, thereby making it possible to form a latent image while avoiding partial stains that occur when the cleaning means comes into contact with the cleaning means and before the contact.

Furthermore, after the completion of the transfer (end of process), the cleaning means is operated to remove the residual toner, and then the cleaning means is separated from the rotating body. Further, after the cleaning means is separated from the rotary body, the rotary body is rotated while the developing means is operated, and the rotary body is cleaned by the developing means.

This rotating rotating body is now here! The effect will be improved if the surface of the rotating body is removed and the potential is approximately equalized so that the electric potential does not appear.

As a result, the surface of the rotating body and the cleaning means can be left uncontaminated, and image formation after the apparatus is stopped is extremely good. An embodiment will be described using an electrophotographic copying apparatus according to the process shown in FIG. 1.

FIG. 2 shows a book using a row 2 developer device for applying a liquid developer to the photoreceptor 1 through rows 29 for development. 1-8
is the same as that in Figure 1.

Reference numeral 1 is a drum-shaped version of the aforementioned endless three-layer photoreceptor. Reference numeral 010 is a well-known cleaning blade, which is provided so that its edge comes into contact with the surface of the rotating downward portion of the drum during cleaning.

Reference numeral 12 denotes a lamp for exposing the original, and reference numeral 14 denotes an optical system that images the original light over the entire surface of the photoreceptor 1.

Exposure promotion is performed by rotating the lamp 12 in synchronization with the rotation of the drum 1.
, the optical system 14 is moved forward in the direction of the arrow iC, and the original is scanned in three directions through the slit to form an image of the original i on the surface of the drum 1. After the forward movement, the lamp 12 and the optical system 14 move back and return to their original positions.

Reference numeral 11 is a power supply for applying a bias voltage to low 2 to increase the amount of toner adhesion or to remove capri.

In this example, before the exposure process is executed, the developing roller 9 is brought into contact with the rotating body, and after the contact tip surface has passed through the blade area, the cleaning blade 10 is brought into contact with the rotating body 1, and the rotating body 1 is allowed to idle for a predetermined period of time. Charger 2, 4 and lamp 1
2, an electrostatic latent image is formed on the rotating body 1.

After the transfer process is completed, the cleaning blade 10 and the developing roller 29 are brought into contact with each other, the rotating body I is allowed to rotate idly for a predetermined period of time, and then the cleaning blade is brought out of contact with the developing roller 29, and after the contacting tip surface thereof passes through the roller area, the developing roller is brought into contact with the cleaning blade 10 and the developing row 29. Make the rollers non-contact.

By the way, the states of the first image row 29 and the cleaning blade 10 are (1) a developing operation state where the roller 9 is in contact with the photoreceptor, (2) a state where the roller 9 is not in contact, and (3) a cleaning operation where the blade 10 is in contact with the photoreceptor. Condition (4) Blade 1
0 indicates non-contact or leaning non-operation state. From these combinations, five combinations are used in this example.

That is, when the power of the copying machine is turned on in step A before copying in FIG. 3, the photoreceptor 1 rotates, but neither the cleaning blade 10 nor the developing roller 9 is brought into contact with the photoreceptor 1. Before the same power switch, Blade 10. Since the roller 9 is not brought into contact with the developing roller 29 and the cleaning blade 100), it is possible to avoid toner from locally adhering to the photoreceptor due to back-turning of the liquid due to capillary development.

It is also possible to contact the row 29 at the same time as the power is turned on.

In step B, step C brings the cleaning blade 10 out of contact with the photoreceptor 1, but brings the developing roller 25 into contact with the photoreceptor 1 and rotates the photoreceptor. This makes it possible to wet the entire surface of the photoreceptor 1, thereby reducing the frictional resistance between the photoreceptor 1 and the cleaning blade 6, and making it easier to clean.

At this time, the potential on the photoreceptor is preferably a non-developing potential, but it is practically arbitrary.

In step C, the cleaning blade 10 is brought into an operating state in which it is in contact with the photoreceptor l. During this step, when the copy button is turned on after completely cleaning all sides and sides, copying is performed. After the completion of the transfer, the toner remaining on the surface of the drum 1 is cleaned before it dries.

Here, cleaning the entire circumferential surface means rotating the rotating body while keeping the blade in contact with the blade for at least the distance from the cleaning castle to the latent image forming area (m1 source area).

In step D, the cleaning blade 10 is brought out of contact with the photoreceptor 1 while the row 29 remains in contact with the photoreceptor 1, and the photoreceptor 1 is rotated so that its entire surface is completely cleaned by the developing roller 9 without using the cleaning blade. At this time, the photoreceptor 1 is at a non-developing potential, and if necessary, the cleaning effect can be increased by applying a bias voltage to the roller using the bias power supply 11 to prevent toner from adhering to the photoreceptor. It is. The non-development potential of the photoreceptor is obtained by removing static electricity from the surface of the photoreceptor using light, AO corona discharge, or the like. It is also possible to selectively apply biases of different polarities or potentials to the developing roller in step C and step Df and C). In the final step E, both the cleaning blade 10 and the developing roller 9 are brought out of contact with the photoreceptor 1, and the rotation of the photoreceptor is stopped. This prevents toner from adhering to the blade developing roller and photoreceptor 7 and drying and accumulating due to capillary action on the cleaning blade or the photoreceptor of the developing row 2 during a copy pause, as in step A.

An example of a 7-can control circuit for a copying machine for obtaining the above steps will be explained with reference to FIG. 4 and its time chart in FIG. 5.

41 to 43 are step signals from the Q terminal by impulse signals to the S terminal (step signals in the opposite direction for Q)
The well-known seven lip-flops 44 to 49 each output an input step signal after a delay time t1xt6, and are released by an inno signal to the res terminal.
51 is a well-known differentiation circuit for forming impulses; 52 to 55 are well-known inverter circuits to invert input signals; 56 is a well-known OR circuit; 57 to 61 is a well-known AND circuit, 8w is the main switch signal for turning on the copier,
CP is an input signal for starting copying using the copy button;
FjND is a signal indicating that the copying process has ended;
ROT rotates the photosensitive drum 1, so 9) Output signal, D
EV is a signal for bringing the developing roller 9 into contact with the photoreceptor, 0
LIN is a signal for bringing the blade 10 into contact with the photoreceptor, 0HAGI.

0HAG2.0HAG3 are operating signals for the primary charger 2, secondary charger 4, and transfer charger 7, respectively, LAMPI is the lighting signal for the lamp 12 for light image exposure, and LAMP2 is the :)/program for full-surface exposure. 4 lighting signal, OPT is optical scanning system 14
Signals T1 to T6 for the reciprocating motion of are output signals from timers 44 to 49.

Signals DEV and 0LIN are input to solenoids that bring the roller and blade into contact, and RoT and LAMP are input.

0HAG is input to a relay that turns on the energizing line to the drum motor, lamp, and high-voltage transformer, and QPT is input to a clutch for moving the optical system in synchronization with the drum motor.

Each of the above signals is generated at the timing shown in FIG. 5. To explain the 0 operation, the drum starts rotating as soon as the power switch is turned on, the developing device is activated after T1, and the blade is activated after T2.

After that, press the copy button and at the same time signal C14AG2
, LAMP2J: S, yy 5, A Q COF The discharger 4 is activated, the exposure switch 12 is turned on in response to the signal LAMP1, and after T3, exposure scanning of the original starts, forming a silent train. When the scanning is completed, the lamp 12 and charger 2 are turned off, and the EN obtained when the optical system returns to its original position.
From the D signal to T4, the lamp 5, the AO corona discharger 4, and the blade LO are rotated while being turned on to remove static electricity, bring the surface to a uniform potential, and remove residual toner before drying. Thereafter, during T5, the operation of the blade is turned off to prevent toner from adhering to the grade, and the drum rotates idly, and after T6, the rotation of the drum is stopped.

Primary charging operates earlier than exposure depending on the position of the secondary charger on the photoconductor and the exposure area. Further, the END signal corresponds to the end of transfer.

Further, the time period T4 to T6 is preferably at least one rotation of the drum or more, but Tl-Ta must be determined in consideration of the copying speed. Here, the rotation of the drum and the operation of the developing device may be turned on and off at the same time, or the rotation of the drum may be stopped if the copy button is not pressed within a predetermined time after SW. The delay times Tl to T6 are determined by a well-known timer circuit that uses capacitor charging time, but if the photoreceptor on the drum is endless, a time signal is obtained by counting a series of clock pulses generated as the drum rotates. well-known circuit,
Alternatively, if it has an end, it can be formed by a circuit that obtains a time signal at a cam position provided on the drum.

FIG. 6 shows an example in which a liquid is pumped up from a solvent 62 to a developing tray 60 by a pump 61 and development is performed there. blade,
The state of the developing unit is the same as that of states (1) to (4) in FIG. 2, except that the developing row 2 is brought into contact and not in contact with the pump roller 1. In this case as well, the fourth
Sequence control similar to that shown in FIGS. 5 and 5 is performed.

FIG. 7 is similar to the developing system shown in FIG. 6, and 70 is a pipe that supplies the developer pumped up by the pump 61 to the contact area between the blade and the surface of the photoreceptor. The operation timing follows FIG. 6.

Reference numeral 71 denotes a corona charger for squeezing out the developer adhering to the surface of the photoreceptor of the developing device. This charger is synchronized with the operation of the developer, but when the surface of the photoreceptor that is about to start development passes the charger position, the charger is turned on, and the tip of the photoreceptor surface that has completed development is positioned at the charger position. It is more preferable to turn off the charger when passing through.

In this example, since the surface of the photoreceptor is wetted by the liquid from the pipe 70, the blade 1
You can touch 0.

Therefore, when the power switch is turned on, the pump 61 is turned on, and then the blade 10 is brought into contact with the photoreceptor and the photoreceptor is rotated for a predetermined period of time. The photoreceptor may start rotating in synchronization with turning on the power switch.

Furthermore, if a developer moisture absorbing and retaining member (such as a sponge) 73 is placed near the blade, which comes in contact with the blade in synchronization with the operation (contact or non-contact), the blade can come into contact with the surface of the photoreceptor almost at the same time as the power switch is turned on.

If the blade has a property of having less contact with the surface, or if a roller cleaner or plank cleaner is used instead of the blade, the cleaner can be brought into contact with the surface at the same time as the power switch is turned on.

In short, the blade is brought into contact with the wet photoreceptor surface and the blade is brought into contact with the photoreceptor before electrostatic latent image formation.

The term "blade contact" means that the blade is brought into pressure contact with the photoreceptor to the point where it can perform a cleaning action. Therefore, the blade can also be brought into the above state by being gradually pressed against it.

FIG. 8 shows another embodiment of the present invention. 1 to 4 in the figure are second
It is the same as the one shown in the figure.

The structure of the developing row 2- is such that a central rigid body is covered with elastic open cells, and the elastic open cells are further covered with a layer having a large number of through holes. When the developing row 29 comes into pressure contact with the photoreceptor 1, the contact surface does not deform in a direction parallel to the contact surface at the pressure contact position, but is elastically deformed in a direction perpendicular to the contact surface. Reference numeral 85 denotes a refresh row 2 which presses the developing roller in the developer 89 held in the inner container 86 and is used to replace the developer contained in the elastic open cell of the developing roller 9. The process sequence is shown in FIG.

In step B, the cleaning blade 10 is brought out of contact with the photoreceptor 1. The developing roller 9 is brought into contact with the photoreceptor 1 and the refresh roller 85, and the pump 88 is operated to supply developer 89 from the developer tub 87 to the inner container 86, thereby rotating the photoreceptor. As a result, when the developing roller 29 comes into contact with the photoreceptor 1, the developing acid solution 89 contained in the elastic open cell in the developing roller 9 is squeezed out through the layer having a large number of through holes and wets the entire surface of the photoreceptor. Therefore, the frictional resistance between the photoreceptor 1 and the cleaning blade 6 at the time of starting copying is reduced.

During this time, it is preferable to turn on the AO charge 4, but the potential on the photoreceptor is arbitrary. In step 0, the cleaning blade 10 and the developing row 29 are brought into contact with the photoreceptor 1 to perform preliminary y-ning.

During this step, the copy is made after thoroughly cleaning the surface. The electrostatic latent image on the photoreceptor 1 is developed by a developing row 29.
The process of creating a visual image is as follows.

The developing roller 9 rotates in the direction of the arrow in the figure at the same speed as the photoreceptor. When the developing roller 29 comes into pressure contact with the photoreceptor 1, the developer is pumped up by the rotational force of the developing roller and the developer contained in the elastic open-cell foam squeezed out by the pressure contact between the roller and the photoreceptor 1. The electrostatic latent image on the photoreceptor is visualized by the liquid. The developing row 29 absorbs and removes the excess developer on the photoreceptor using the restoring force of the elastic open cell material when the pressure contact with the photoreceptor is released.

The developing row 29 further rotates and comes into pressure contact with the refresh row 215 in the developing solution in the middle container 86, and the developing process is repeated in which the developer is exchanged and comes into contact with the photoreceptor again. In step D, the developing process is repeated. The cleaning blade 10 is brought out of contact with the photoreceptor 1 while the row 29 remains in contact with the photoreceptor 1, and the photoreceptor 1 is rotated so that the entire surface of the photoreceptor 1 is cleaned by the phenomenon row 29 without using the cleaning blade. At this time, it is possible to increase the effect by setting the photoreceptor 1 to a non-'fA#@ position, or by applying a bias blood pressure to the developing row 29 from the bias power supply 11 as necessary.

It is also possible to selectively apply biases of different polarities or potentials to the phenomenon row 29 in steps C and D, respectively. While the inner container 86 is filled with the phenomenon liquid during step D, when the developing roller 98 is released from the photoreceptor 1 in step E, which will be described later, the developer drawn up by the phenomenon roller 29 and the phenomenon liquid squeezed out from the elastic open cell body are removed. It may adhere to the photoreceptor and dry and solidify during copying pauses, resulting in poor cleaning. Therefore, in this embodiment, the above-mentioned drawbacks can be easily eliminated by stopping the pump for supplying the phenomenon liquid to the medium container. That is, by stopping the pump 18 during step E, the phenomenon liquid in the inner container 86 is removed. fA consideration roller 9 is a photoreceptor and refresh o
Rotates in full air with -95 pressure. phenomenon roller 9
The phenomenon liquid contained in the continuous elastic bubbles inside is removed by pressure contact with the refresh roller, and now fA does not contain liquid.
To clean the surface of a photoreceptor when it comes into contact with a photoreceptor, and to prevent unnecessary phenomenon liquid from remaining on the surface of the photoreceptor even when it is separated from the photoreceptor. Step E: Both the beam lining blade 10 and the developing row 5-9 are not in contact with the photoreceptor 1. Similar to step A, 〇〇 is step E in the sequence shown in Fig. 3.

This control can be performed using FIGS. 4 and 5.
8 is turned on depending on where Tl lives, and turned off depending on where T4 lives.

In the above example, exposure does not start even if the copy button is turned on for a predetermined period of time (while the photoreceptor is rotating) after the blade contacts, but after that time has passed, the exposure does not start even after the second fixed period of time has elapsed.
When not in use, the rotation of the photoreceptor can be stopped to protect the surface of the photoreceptor.At the same time, the blade or the blade and the developing roller may be rubbed without contact. If the copy button is turned on after the rotating body is stopped, the optical system starts to move for the g source after rotating the photoconductor by at least the distance of the exposure area (predetermined rotation) from at least the cleaning force.

However, when the blade and the current European roller are made non-contact, exposure is started through steps similar to those from turning on the copy button and turning on the power switch. Also, if the re-hicopy button is turned on during step 0 during the copy pause, exposure is started at the same time as the button is turned on or after a predetermined rotation speed. When the copy button is turned on in step D, the blade is brought into contact with the copy button, and after a predetermined rotation, exposure is started. Step E
When the copy button is turned on at this time, exposure is started after the scraps are rotated at a constant rate, in which the developer O-/F and the blade are sequentially brought into contact with each other as in the step described above. When the copy button is turned on after the photoconductor rotation has stopped, the process goes through the same steps as when turning on the power switch.
Original start. It is also possible to turn off the power switch when the rotating body stops.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the electrophotographic process, and Figure 2 is a schematic diagram of the electrophotographic process. Figure aIa is a time chart of the electrophotographic method in this embodiment, Figure 4 is an example of sequence control rotation in this embodiment, Figure 5 is a time chart of Figure 4, and Figure 6.7.8.
The figure is a schematic diagram of another electrophotographic process, and FIG. 9 is a time chart in FIG. #I8. 9 in Figure 8 is the developing row 2
．． 85 is an auxiliary roller, 88 is a liquid pump, 87 is a developer container, 11 is a bias power source, and 10 is a cleaning blade. , Applicant: Canon Corporation. Procedural amendment (c) July 18, 1985 1, Indication of the case 1988 Patent Application No. 258561 2, Name of the invention Image forming device 3, Person making the amendment Relationship to the case Patent applicant address Tokyo 3-30-2 Shimomaruko, Ota-ku Name (100
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4. Agent residence: Canon Co., Ltd., 3-30-2 Shimomaruko, Ota-ku, Tokyo 148 (telephone: 75B-2111). 5. Date of amendment order (shipment date): June 25, 1985. 6. Subject of amendment. Specification 7, contents of amendment As per the engraving and attached sheet of the specification originally attached to the application (no change in content)

Claims (1)

[Claims] A rotating body, means for forming an electrostatic latent image on the rotating body, means for developing the electrostatic latent image, means for transferring a visible image by the developing means onto a transfer material, and a means for reproducing the rotating body. The apparatus has means for cleaning the rotary body for use, and a control means for operating the cleaning means in a non-contact manner, and after the completion of transfer, the rotary body is rotated backward and the cleaning means is operated for a predetermined period of time; An image forming apparatus characterized in that the cleaning means is then brought into contact with the cleaning means.