JPH01177584A - Image forming method for electrostatic recorder - Google Patents

Abstract

PURPOSE:To prevent black lines from being formed on a recording paper by reducing the exposure of an exposure device at the time of terminating exposure of the exposure device in the pre-fatigue treatment. CONSTITUTION:When exposure of a diode array 4 will be terminated, the diode array 4 is flickered and the lighting duty is gradually reduced to gradually reduce the quantity of light. Consequently, the surface potential of a photosensitive drum 2 is gradually increased (graded) from the area potential and a peak potential does not generated. Thus, black lines of toner are prevented from being formed on a recording paper 7. The time interval and the value of the reduction of the lighting duty of the diode array 4 can be arbitrarily selected at any time before a photosensitive drum 2 is rotated once or more to start an image area after the start of pre-exposure sequence and lighting of the diode array 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrostatic recording device such as a copier or an electrostatic printer. The present invention relates to an image forming method for an electrostatic recording device in which a pre-fatigue treatment for performing charging and exposure prior to the actual recording operation is required.

BACKGROUND ART Generally, in electrostatic recording devices used as copying machines or electrostatic printers, pre-fatigue treatment is often performed prior to the actual recording operation. This method, as disclosed in, for example, Japanese Patent Publication No. 44-2550, is a method in which the photoreceptor is simultaneously charged and exposed (pre-exposure) prior to the actual recording operation of the photoreceptor. In the case of reversal development, after charging the F photoconductor in the charging device and rotating the photoconductor for more than 1 minute while exposing it to the exposure light source, only the exposure light source is turned off, and then normal recording is performed. :
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First, the internal structure of a typical electrostatic recording device will be explained with reference to the side sectional view of FIG.

In the figure, numeral 1 is the main body of the apparatus, which is constructed in the shape of a housing. A photosensitive drum 2 is rotatably mounted in the center of the main body 1.

A charging corotron 3, a diode array 4, and a short focus lens array 5 for uniformly charging the photoreceptor drum 2 to form an entire electrostatic latent image are placed in contact with the top of the photoreceptor drum 2, which has a circular shape. It is arranged.

On the downstream side of the short focal length lens array 50 in the direction of rotation of the photoreceptor drum 20, a developer Ve[6 is arranged which converts the latent image formed on the surface of the photoreceptor drum 2 into an S image by toner development. .

A device V on the downstream side of the developing device 6 includes a transfer corotron 8 for transferring the developed toner image formed on the surface of the photosensitive drum 2 onto the recording paper 7, and a toner electrostatically attached to the photosensitive drum 2. A separation corotron 9 for separating the layered recording paper 7 is arranged.

A paper feed cassette (10) containing He recording paper is removably attached to the right side of the main body (1). A paper feed roller 11 is provided for feeding 7 sheets one by one.

Also, the 'F flow gy, vc of this paper feed roller 11 is the recording paper 7
Registration roller 12 for adjusting paper feeding timing
is provided.

On the downstream side of the separation corotron 9, there is a conveyor belt 1 for conveying the recording paper 7 on which the toner image of the missing layer has been transferred.
3 is provided, and downstream thereof 911K is a constant N roller equipped with a heat roller 14.7 and a pressure roller 15 for applying pressure and heating to fix the missing layer toner transferred onto the dC recording paper 7. A loading case 16 is provided.

A cleaning device Mt18 having a cleaning blade 17 for scraping off and removing toner remaining on the surface of the photosensitive drum 2 without being transferred to the recording paper 7 is provided above the conveyor belt 13. Furthermore, an erase lamp 19 is provided on the downstream side along the rotational direction of the photoreceptor drum 2 for erasing the load remaining on the surface of the photoreceptor drum 2.

FIG. 4 is a schematic diagram showing an example of the arrangement positional relationship of each member around the photoreceptor drum 2 of the apparatus shown in FIG. It is clearly shown.

That is, the distance between the diode array 4 and the developing device 6 ■
is 621 m% on the outer circumference of the photoreceptor drum 2. The distance between the developing device 6 and the position where the recording paper 7 contacts the photoreceptor drum 2 is ■
is 51 m+, the distance between the contact position of the recording paper 7 on the photosensitive drum 2 and the transfer corotron 8 is 12 mm, and the distance between the transfer corotron 8 and the separating corotron 9 is 18-m. The distance ■ between the separating corotron 9 and the cleaning blade 17 is 66 no, the distance 0 between the cleaning blade 17 and the erase lamp 19 is 36 no,
Distance between erase slang 19 and charged corotron 3■
is 18 m, and the distance ■ between the charged corotron 3 and the diode array 4 is 20 m.

FIGS. 5(a) to 5(h) are schematic diagrams for explaining TA operation of an electrostatic recording apparatus having the above-described configuration and member arrangement.

In FIG. 5, the photosensitive drum 2 is rotating K in the direction of the arrow (clockwise in the figure).

First, as shown in FIG.
At the same time, FIG.
The surface is exposed to light.

In the figure, ■ indicates the charging potential caused by the charged corotron 3r, and O indicates the state after it has been exposed to light by the diode array 4 and the short focus lens array 5.

Then, after passing through the state shown in FIG. 5(C), the rotating direction Vc of the photoreceptor drum 2 is collapsed as shown in FIG. When the exposure ends when the exposure position according to 5&C is reached, a sharp potential is generated at the boundary between the exposed area and the unexposed area, that is, across the area.

FIG. 6 is a graph showing the state of generation of sharp potential, in which the vertical axis shows the surface potential of the photosensitive drum 2, and the horizontal axis shows the local direction of the surface of the photosensitive drum 20. concrete V
The low potential part on the left half of the graph in Figure 6 shows the potential of the exposed part, and the high potential part on the right half shows the unexposed part. corresponds to the area mentioned above.

In this region Bl/c, a sharp potential even higher than the unexposed portion is generated.

In this way, when the diode array 4 is turned off all at once, the potential difference of about 500V in this example is reduced by the response speed of a single source (the equation 1
0 to several 100 nanoseconds).

Next, as shown in FIG. 5(e)K, the diode array 4 and the short focal length lens array 5 are exposed to light from the area C on the downstream side of the area B on the surface of the photosensitive drum 2, but this time, the electrostatic latent image is completely formed. The exposure begins.

When area C reaches the developing position by developing device 6Vc.

Development of the latent image by the developing device 6 starts. When this area C reaches the position of the transfer corotron 8, the recording paper 7 moves between the photoreceptor drum 2 and the transfer corotron 8 in synchronization with the circumferential speed of the photoreceptor drum 2. The toner Sa formed on the surface of the photosensitive drum 2 is transferred to the recording paper 71C.

During the above operations, the blade 1 of the greasing device 18
As shown in FIG.
Subtract n and add a layer, so this n is the next accent Ya@f'F=V
At this time, as shown in FIG. 5, a black line is formed on the recording paper 7 as a facial image.

Therefore, the conventional electrostatic five-scythe device has the disadvantage that a black line is formed on the recording paper ``7'' when the pre-fatigue treatment is performed.

Figure 7 shows the procedure shown in the fifth factor mentioned above on A4-sized recording paper 7.
12 is a timing chart showing a detailed sequence when executed using the .

In addition, each number in this Figure 4 and the D shown at the top
The rotation of the photosensitive drum 2 with a diameter of 9 degrees from the time when the start instruction for the SLP recording operation, that is, the print request, is issued - the distance traveled by its outer periphery (unit: ■). Of the signals shown at the left end of FIG.
Signals to which bars ('-") are added are so-called low active signals in which a low level is significant.

First, when a print request signal is received (at position 0 at the left end in FIG. 4), the main motor starts rotating as the signal MM changes to low level, and the photosensitive drum 20 starts rotating. The signal CLS changes to a low level when the photoreceptor drum 2 rotates 57 degrees, and the cleaning blade 17 presses the photoreceptor drum 2.

Then, when the photosensitive drum 2 has rotated 681 times, the signal [
(VM changes to low level and the charging corotron 3 starts operating, that is, starts charging the photoreceptor drum 2, and from this point on, the photoreceptor drum 2 is charged for 10 ym (total 7
8no) At the time of rotation, the signal LED changes to the high level and the diode array 4 lights up (all the diodes constituting the diode array 4 are lit continuously)I, , f9 exposure sequence starts n.

As described above, the pre-exposure for pre-fatigue treatment of the photoreceptor drum 2 starts, and after that, the photoreceptor drum 2 rotates once (approximately 2
When the photoreceptor drum 2 has rotated more than 83 m), in this example, after the start of the pre-exposure sequence, the photoreceptor drum 2 has further rotated about 3108 m (approx. 388 was from the start of rotation of the photoreceptor drum 2), the signal LED changes to low level. The diode array 4 is turned off and the pre-exposure sequence is completed.

After the 1st exposure sequence is completed, in this example, the print request check signal P RRE Q Ch is sent again when the photoconductor drum has rotated 468 times from the start of 20 revolutions.
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9) After checking and confirming the request signal, start the print sequence.

At the beginning of the print sequence, the signal PSC is set to 4.
At the time of 70■, the level is changed to low, and the paper feed roller 110 rotations start n. After the paper feed roller 11 starts to rotate, when the photoreceptor drum 2 rotates by 15 m, a target image is formed on the surface of the photoreceptor drum 2, and an image is formed on the surface of the photoreceptor drum 2 at the tip end. 540 to match
After temporarily stopping the paper feed roller 11 at time m, the signal P
The register roller 12 starts rotating at a time point of 543 m+V when RC changes to a low level. Konnibiki 608maO
At this point, the level is sequentially changed to low, and the transfer corotron 8 and separation gorotron 9 start operation a. As a result, the electrostatic latent image formed on the photosensitive drum 2Vc is developed into a toner image, and this developed image is transferred onto the recording paper 7.

Eventually, when the rotation amount of the photoreceptor drum 2 reaches 812 mm, the end sequence starts, and at 855 mm, the signal PRc changes to the helmet pulse, and the register roller 12 stops A, 93
At the points of 4 mm and 95 Qm+, the operations of the transfer corotron 8 and the separation corotron 9 are stopped.

Note that VSYNC in the figure is a vertical synchronizing signal, and the electrostatic latent image is formed while this signal is at a low level. Also DE
V-8 uses developing bias.

TSO is a control signal for the toner replenishment clutch, JAMI is a control signal for the paper feed jam sensor, and JAM3 is a control signal for the fixing jam sensor. Further, TPO is an output signal of the total paper counter when operating a, PRREQcheck is a print request check signal, and 5TREQcheck is a status request check signal.

(/9 Problems to be Solved by the Invention As mentioned above, in the conventional electrostatic recording device, the off timing of pre-exposure, that is, the diode array 4 which is the exposure light source
Since a sudden potential change occurs at the position of the photosensitive drum 2 at the off timing, the waste toner accumulated on the cleaning blade 17 of the cleaning device 18 is attracted to this part and forms a black line on the n1 recording paper 7. The problem is that it appears.

The present invention has been made in order to solve the problems of the conventional electrostatic recording device as described above, and is an electrostatic recording device that can avoid the formation of black lines on recording paper during pre-fatigue treatment of a photoreceptor. The purpose is to provide an image forming method for an apparatus.

B) Means for Solving the Problems The present invention involves exposing the surface of a photoreceptor charged by a charging means to light using an exposure means, forming an electrostatic latent image, and developing the formed latent image using a developing means. An electrostatic recording device that performs an image forming operation in which a toner image is formed by a transfer means, the toner image is transferred to a recording paper by a transfer means, and the toner remaining on the surface of the photoreceptor after the image transfer is removed by a cleaning means. , prior to the image forming operation.

In the image forming method in which the photoreceptor is subjected to pre-fatigue treatment by charging by the charging device and exposure by the exposure device, when the exposure by the exposure device for the pre-fatigue treatment is completed, the exposure irradiation amount of the exposure device is reduced. This is an image forming method for an electrostatic recording device, which is characterized by gradually decreasing the amount.

(E) Effect In the present invention, since the exposure dose of the exposure device gradually decreases, no sharp potential is generated.

Therefore, no black line of toner is formed on the photoreceptor.

(v) Examples The present invention will be described in detail below based on the drawings showing the examples. This is an example in which the present invention is applied to an electrostatic recording device having the same configuration as shown.

In this embodiment, when the exposure of the diode array 4 is finished, as shown in FIG. 1, the diode array 4 is blinked and the lighting duty is gradually lowered to gradually reduce the amount of light. .

Then, the surface potential on the photosensitive drum 2 gradually increases from region B (graded stiffness and sharp potential do not occur).

Therefore, no black line of toner is formed in area B.

Note that the pre-exposure sequence starts at the time interval and value of decreasing the lighting duty of the diode array 4. After the diode array 4 is turned on, the photoreceptor drum 2 rotates more than once. , can be arbitrarily selected from the start to the end of the image area.

FIG. 2 is a graph showing the relationship between the surface potential on the photosensitive drum 2 and the lighting duty of the diode array 4. As shown in FIG.

As is clear from this graph, the lighting temperature is 2.
When it becomes 551 or more, the surface potential on the photosensitive drum 2 does not change.

(g) Effects of the invention In the invention, the exposure dose of the exposure device gradually decreases, so no sharp potential is generated.

Therefore, a black line of toner is not formed on the photoreceptor, and the problems of the prior art are solved at once.

[Brief explanation of the drawing]

FIG. 1 is a graph showing all the surface potentials on the photoreceptor drum in one embodiment of the present invention, FIG. 2 is a graph showing the relationship between the surface potential on the photoreceptor drum and the lighting duty, and FIG. FIG. 4 is a schematic diagram showing the internal structure of the electrostatic recording device to which it is applied. FIG. 4 is a schematic diagram showing the positional relationship of the photosensitive drum and each member arranged around it.
) is a schematic diagram showing the procedure of the conventional method, and FIG. 6 is a graph showing the sharp potential generated on the surface of the photoreceptor drum during pre-fatigue treatment. FIG. 7 is a timing chart showing a detailed sequence of the procedure shown in FIG.

Claims (1)

[Claims] 1. The surface of the photoreceptor charged by the charging means is exposed by the exposure means to form an electrostatic latent image, and the formed latent image is developed by the developing means to form a toner image. The image is formed by an electrostatic recording device that performs an image forming operation of forming a developed image, transferring the developed image to a recording paper by a transfer means, and removing toner remaining on the surface of the photoreceptor after the developed image transfer by a cleaning means. Prior to the operation,
In the image forming method in which the photoreceptor is subjected to pre-fatigue treatment by charging by the charging device and exposure by the exposure device, when the exposure by the exposure device for the pre-fatigue treatment is completed, the exposure irradiation amount of the exposure device is reduced. An image forming method for an electrostatic recording device, characterized by gradually decreasing the amount of image. 2. The image forming method for an electrostatic recording apparatus according to claim 1, wherein the exposure device is equipped with a blinking light source, and the exposure dose is gradually reduced by changing the lighting duty.