JPS6197680A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To always obtain high-quality picture images which is uniform in brightness, by comparing measured surface potential of a photosensitive body with reference potential and actuating a destaticizing section by a period in which the photosensitive body is rotated by a set distance. CONSTITUTION:A power supply is turned on and a destaticizing lamp 8 and electrostatic charger 3 are turned on by a period when a photosensitive body 1 makes one turn. Then the surface potential of the photosensitive body 1 is measured by means of a measuring instrument 32 and the measured value is compared with previously set reference potential at a comparator 35. When the measured value is higher than the reference potential, the lamp 8 and charger 3 are again turned on by a period when the photosensitive body 1 is rotated by a previously set distance and the main processes of exposing and developing are performed thereafter. When the measured value is lower than the reference potential, the main processes are performed immediately. Therefore, even when the sensitivity of the photosensitive body is too high and, as a result, the surface potential of the photosensitive body is high because of the initial stage of the use of the body, the surface potential is lowered and high-quality electrophotographs which are uniform in brightness cab be obtained always.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes at least a charging section, an exposing section, a developing section, and a static eliminating section arranged and provided in sequence along the direction of movement of a photoreceptor, and charging at the charging section. This invention relates to an improvement in an electrophotographic device in which an image is formed on the photoreceptor surface of a photoreceptor in an exposure section, and further developed in a development section to obtain a photographic image, and the photoreceptor is neutralized in a charge removal section in preparation for the next charging. .

[Prior Art] Conventionally, in this type of electrophotographic apparatus, exposure and development were performed sequentially without taking any measures to prevent the surface potential of the photoreceptor from becoming abnormally high due to charging by the charging section. It was used to obtain electronic photographs.

[Problems to be Solved by the Invention] By the way, in this type of device, when the photoconductor is in a new state, and when it is used for the first time or after not being used for a while, the photoconductor is The sensitivity may become too good and the surface potential due to charging may become abnormally high. However, in such a case, the above-mentioned conventional apparatus has a problem in that image formation by exposure is insufficient, resulting in an electrophotograph that is too dark, making it impossible to obtain a high-quality electrophotograph.

This invention was made to solve this problem, and when the sensitivity of the photoreceptor increases and the surface potential of the photoreceptor becomes abnormally high due to charging, the surface potential is lowered by removing the charge from the photoreceptor. It is an object of the present invention to provide an electrophotographic apparatus that can always obtain high-quality electrophotographs with substantially constant brightness by performing exposure and development operations after exposure and development.

Another object of the present invention is to provide an electrophotographic apparatus that can obtain higher quality electrophotographs by performing exposure in a state where the surface potential of the photoreceptor is always below a preset reference potential.

[Means for Solving the Problems] The present invention includes at least a charging section, an exposure section, a developing section, and a defrosting section that are sequentially arranged along the moving direction of the photoconductor, and the photoconductor charged in the charging section. In an electrophotographic apparatus, an image is formed on a photoreceptor surface in an exposure section, and further developed in a development section to obtain a photographic image, and the photoreceptor is neutralized in a static elimination section to prepare for the next charging.
Compares and determines whether the surface potential measured by this measuring device exceeds a preset reference potential with a surface potential measuring device that is installed between the charging section and the exposing section and measures the surface potential of the photoreceptor. and 1il, which operates a static eliminator until the photoreceptor moves a preset distance when the comparison means determines that the surface potential exceeds the reference potential.
Furthermore, in the present invention, when the comparison means determines that the surface potential exceeds the reference potential, the static eliminator is operated until the surface potential becomes equal to or less than the reference potential. IIJtl1 to control
This means that a means has been established.

[Function] In the present invention having such a configuration, the surface potential of the photoreceptor immediately after being charged by the ζ charging section is measured with a measuring device, and if the surface potential exceeds the reference potential, the photoreceptor is The static eliminator is operated until the photoreceptor moves a distance to lower the potential on the surface of the photoreceptor necessary for image formation, and then exposure is started.

In addition, if the surface potential of the photoconductor exceeds the reference potential, the static eliminator is operated until the surface potential falls below the reference potential, ensuring that the potential of the photoconductor surface necessary for image formation is below the reference potential. I try to start exposure after lowering the value.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, the present invention will be described as applied to an electrophotographic printer using a laser.

FIG. 1 shows the overall configuration, and 1 is a casing. A photosensitive drum 2 as a photosensitive member having a photosensitive surface formed along the outer periphery is installed in the center of the housing 1, and the photosensitive drum 2 is rotated at a constant speed by a motor (not shown). Along the circumference of the photosensitive drum 2,
A charging device 3 forming a charging section, a generator 5 for scanning laser beam 4 forming an exposure section, a developing section 6, a transfer section 7 having a transfer charger, a static elimination lamp 8 forming a static elimination section, and a wiping O-ra. 9 are arranged.

An insertion slot 1 for a paper feed cassette 1o is provided at the lower side of the housing 1.
1 is formed between the insertion opening 11 and the transfer section 7, and a paper feed roller 13 and a paper feed guide 1 for guiding the paper 12 stored in the paper feed cassette 10 to the transfer section 7.
4 is provided.

Note that a paper insertion section 15 for manually feeding paper is also provided on the side surface of the housing 1.

On the opposite side of the transfer section 7 to the paper feed guide 14, there is a conveyor 16 and two fixing rollers 17a, 17.
A fixing section 18 consisting of b is provided.

As shown in FIG. 2, the laser beam generating device 5 includes a laser light emitting element 51 that is turned on and off according to information;
A rotating polygon 1152 and an fθ lens 53 that horizontally scan the laser beam from the light emitting element 51, a scan start position sensor 54, a scan end position sensor 55, and a reflection that irradiates the laser beams to each sensor 54 and 55, respectively. It consists of mirrors 56 and 57 and a mirror 58 for directing laser light to the photosensitive surface of the photosensitive drum 2.

FIG. 3 is a block diagram showing the circuit configuration, in which 21 is a CPU (central processing unit) constituting the control section, 22 is a CPU 21
23 is a character generator, 24 is an area for storing information for printing, an area for storing flags for control, and a counter. RAM (random access, etc.)
25 is an interface for taking in information from the outside; 26 is various sensors 27 such as the scan start sensor 54 and scan end sensor 55; various lamps 28 such as the static elimination lamp 8; -ja3,
Various charges 1ν29 such as a transfer charger, a motor that rotationally drives the photosensitive drum 2, and a rotating multi-face! This is an I10 boat that performs input/output control for various motors 30 such as the motor that rotationally drives [52], and also controls the output of information to the laser beam generator @5. Said CPI
J21 and ROM22, character generator 23,
RAM24, interface 25, I10 boat 26
is connected to by a pass line 31. Said CP
The U21 stores information input from the outside via the interface 25 in the RAM 24, and when the information is subsequently printed, the information is transferred to the character generator 2.
3 to convert into character pattern information and then I1
0 port 26 to control the output to the laser beam generator [5]. Further, the CPLI 21 selectively controls various sensors 27, various lamps 28, various chargers 29, and various motors 30 via the I10 boat 26 based on program data in the ROM 22.

FIG. 4 is a diagram showing the main part configuration, and the surface potential of the photosensitive surface of the photosensitive drum 2 is measured between the charger 3 and the laser irradiation part R from the laser beam generator 5, and the magnitude of the surface potential is A surface potential measuring device 32 that outputs a proportional voltage signal is arranged, and the output from the measuring device 32 is connected to a resistor R33,
34 are connected in series to a voltage dividing circuit. The voltage dividing point output of the voltage dividing circuit is supplied to one input terminal (+) of the comparator 35. A level signal of a reference potential set by a variable resistor 36 is input to the other input terminal (-) of the comparator 35 .

The comparator 35 outputs a low level signal when the surface potential of the photosensitive drum 2 charged by the charger 3 is below a set reference potential, and outputs a high level signal when it exceeds the reference potential. .

The output of the comparator 35 is waveform-shaped by a Schmitt circuit 37, and then sent to the I10 port 26 by I10P1.
It is supplied as human power. This input is one of the inputs from the various sensors 27 mentioned above.

FIG. 5 shows the control of the main parts performed by the CPU 21. When the power is turned on, initial processing such as RAM clearing is performed first, and then the static elimination lamp 8 is turned on.
, Turn on charger 3.

Rotation of the photosensitive drum 2 is performed sequentially. Subsequently, a time counting operation is started, and the time required for the photosensitive drum 2 to rotate once is counted. When the time has elapsed, the charger 3 is set to 0FFL, and the static elimination lamp 8 is turned off. In this state, next, the state of the surface potential of the photosensitive drum 2 is checked by inputting 110P manual power. l10P 1 person power is “H”;
If it is a novel, it is determined that the surface potential of the photosensitive drum 2 exceeds the reference potential, and the static elimination lamp 8 and charger 3 are turned on again. This state is continued for a period of time until the photosensitive drum 2 rotates a preset distance, and then the charger 3 and the neutralization lamp 8 are turned off.

When this control ends, main processing starts. Also, l
10P 1 When the manual power is at rLJ level, photosensitive drum 2
It is determined that the surface potential of is below the reference potential and the main processing is started immediately. In the main process, an image of information is formed on the surface of the photosensitive drum 2 using a laser beam from a laser beam generator 5, followed by development with toner in a developing section 6, and then an image is formed from a paper feed cassette 10 in a transfer section 7. The image is transferred to the fed paper, and the transferred paper is further fixed by fixing rollers 178, 17b, and then discharged to the outside.

In this way, paper on which information is printed is obtained through the main processing.

In the apparatus according to the embodiment of the present invention having such a configuration, the surface potential of the photosensitive drum 2 is measured before the main processing is started, and when the surface potential exceeds a preset reference potential, the charger 3 is reactivated. The surface potential of the photosensitive drum 2 can be lowered by operating the charge removal lamp 8 and bringing the photosensitive drum 2 into a state similar to when the photosensitive drum 2 has been used several times for printing. Therefore, when actually printing on paper, the surface potential of the photosensitive drum 2 does not become abnormally high at all, and the brightness is approximately constant from the beginning, allowing high-quality printing to be performed at all times. You can obtain high-quality electronic photographs.

In the embodiment described above, when the surface potential of the photosensitive drum 2 exceeds the reference potential, the charger 3 and the static elimination lamp 8 are set to the Rf required for the photosensitive drum 2 to rotate a predetermined distance.
Although the RION operation is not limited to this, for example, as shown in FIG.
1 When the human power is at the rl-IJ level, the static elimination lamp 8 and the charger 3 are turned on again, but the ON time is l10.
P1 may be the time required for human power to reach the rLJ level, that is, the surface potential of the photosensitive drum 2 to be below the reference potential,
By doing this, image formation by exposure can be started after the surface potential of the photosensitive surface of the photosensitive drum 2 is reliably brought below the reference potential, so that image formation can be performed better and higher quality electrophotographs can be obtained. can. In FIG. 6, the time is counted after the static elimination lamp 8 is turned off and before proceeding to the main process so that the photosensitive surface measured by the surface potential measuring device 32 is set at the position where it will be exposed to the laser beam. This is to correct the positional deviation.

In the above embodiments, the present invention was applied to a laser electrophotographic printer, but the present invention is not necessarily limited to this, and can also be applied to a normal copying machine.

[Effects of the Invention] As detailed above, according to the present invention, when the sensitivity of the photoreceptor increases and the surface potential of the photoreceptor due to charging becomes abnormally high, the surface potential is lowered by removing the charge from the photoreceptor. By performing exposure and development operations after the exposure and development, it is possible to provide an electrophotographic apparatus that can always obtain high-quality electrophotographs with substantially constant brightness.

Further, according to the present invention, it is possible to provide an electrophotographic apparatus that can obtain higher quality electrophotographs by performing exposure in a state where the surface potential of the photoreceptor is always equal to or lower than a preset reference potential.

[Brief explanation of drawings]

Figures 1 to 5 show an embodiment of the present invention, with Figure 1 being a diagram showing the overall configuration, Figure 2 being a perspective view showing the configuration of the laser beam generator, and Figure 3 being the circuit configuration. Figure 4 is a block diagram showing the main part configuration, Figure 5 is a block diagram showing the CPI.
FIG. 6 shows another embodiment of the present invention, and is a flowchart showing main part control by the CPU. 2... Photosensitive drum (photoreceptor), 3... Charger < m placement section), 5... Laser beam generator (exposure section), 6... Developing section, 8... Static elimination lamp (static elimination section). Department),
21...CPU (central processing unit), 22...ROM
(read-only memory), 33.34... resistor, 35... comparator (comparison means), 36... variable resistor. Applicant's agent Patent attorney Takehiko Suzue 01 Figure 3 Figure 4 Vision 5 Figure 06

Claims (2)

[Claims] (1) At least a charging section, an exposing section, a developing section, and a static eliminating section are sequentially disposed along the moving direction of the photoconductor, and the exposure section is used to form an image on the photosensitive surface of the photoconductor charged by the charging section. image,
Further, in the electrophotographic apparatus, the photoreceptor is developed in the developing section to obtain a photographic image, and the photoreceptor is neutralized in the static eliminating section to prepare for the next charging. A surface potential measuring device that measures the surface potential of the body; a comparing device that compares and determines whether or not the surface potential measured by the measuring device exceeds a preset reference potential; An electrophotographic apparatus characterized in that the electrophotographic apparatus is further provided with a control means for operating the static eliminator until the photoreceptor moves a preset distance when it is determined that the electric potential exceeds the reference potential. (2) At least a charging section, an exposing section, a developing section, and a static eliminating section are sequentially disposed along the moving direction of the photoconductor, and the exposure section is used to perform an operation on the photosensitive surface of the photoconductor charged by the charging section. image,
Further, in the electrophotographic apparatus, the photoreceptor is developed in the developing section to obtain a photographic image, and the photoreceptor is neutralized in the static eliminating section to prepare for the next charging. A surface potential measuring device that measures the surface potential of the body; a comparing device that compares and determines whether or not the surface potential measured by the measuring device exceeds a preset reference potential; An electrophotographic apparatus comprising: a control means for controlling the operation of the static eliminator until the surface potential becomes equal to or less than the reference potential when it is determined that the surface potential exceeds the reference potential.