JPH067284B2 - Mounting method of photoconductor in electrophotographic printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus which performs an electrophotographic printing operation.

Electrophotographic printing apparatuses are widely used because they can print on plain paper and can print various patterns.
In such an electrophotographic printing apparatus, a laser light source is used as an exposure source, and it is configured as shown in the overall configuration diagram of FIG. 3 and the optical system configuration diagram of FIG.

That is, the photosensitive drum 4 having a photoconductor (photoconductor) on its surface
A charging device 5, a developing device 6, a transfer device 7, a charge eliminating unit 8 and a cleaner 9 are arranged around the periphery of the electrophotographic unit to form an electrophotographic unit, and a laser diode 12, a collimating lens 13, a polygon mirror 14, and F-θ (image formation). ) Lens 1
6, an optical unit for exposure is configured by the mirror 17,
Further, the paper hopper 1, the feeding roller 2, the conveying roller 3, the fixing roller 10, and the stacker 11 constitute a paper handling unit. In such an electrophotographic printer,
Laser light modulated according to a writing image from a laser diode 12 which is a laser source is optically scanned by a polygon mirror 14 rotated by a spindle motor (servo motor) 15 via a collimator lens 13, and F
The photosensitive drum 4 charged by the charger 5 is exposed through the −θ lens 16 and the mirror 17. As a result, a latent image is formed on the photosensitive drum 4, is developed by the developing device 6, is fed by the feeding roller 2 from the paper hopper 1, and is fed by the transfer device 7 onto the paper CP which is fed to the transfer portion by the transfer device 7. Will be transcribed. After that, the paper CP is fixed by the fixing device 10 and stored in the stacker 11, while the photosensitive drum 4 is discharged by the discharging unit 8 and then cleaned by the cleaner 9 to be used for the next latent image formation.

In such a laser printer, as shown in FIG. 4, a laser source 12, a polygon mirror (scanning mirror) are provided as an optical system.
14 and a spindle motor 15 are provided, the laser source 1
An image is formed by scanning the photosensitive drum 4 rotated by the motor 4a with the light of the two spots by the spindle motor 15 rotating the polygon mirror 14 in the X direction of FIG. 4, that is, the main scanning direction. This laser source 1
2 is driven by the modulation signal LEDS corresponding to the writing image, and a point sequence of light corresponding to the modulation signal LEDS is generated from the laser source 12, so that the writing image is formed on the photosensitive drum 4.

In the laser printer as described above, as a photoconductor on which an electrostatic latent image is formed, a photoconductor such as SeTe deposited on a rotary drum made of aluminum is used.

However, a photoconductor such as SeTe has a film thickness and a material configuration that change in the axial direction due to subtle changes in vapor deposition conditions such as a vapor deposition temperature and a vapor deposition direction. Two photoconductor layers described here are provided, one of which is T
A SeTe layer having a content of e of 15 to 25%, and a SeTe layer having a content of Te of 1 to 5% are used.
The higher the content of e, the better the photosensitivity.

Therefore, as is well known in the art, there is a manufacturing problem that the charging characteristic changes in the axial direction due to the change in the film thickness, and the photosensitivity changes due to the change in the material configuration. Therefore, in this type of printing apparatus, there are problems such as uneven density in the axial direction or a change in line width.

The change in the line width will be described below.

FIG. 7 is a diagram for explaining changes in line width.

In the figure, the horizontal axis represents the position on the surface of the photoconductor, and the vertical axis represents the potential level on the surface of the photoconductor. In addition, the development start voltage (14
0 V) is a voltage determined by the relationship between the electrostatic force of the toner and the magnetic force of a mag roll (not shown) in the developing device,
It is the minimum voltage required for the magnetic toner to adhere onto the photoreceptor from the non-magnetic sleeve containing the mag roll.

Furthermore, 800V is the charging voltage on the photosensitive member when the initial charging is performed by the charger 5.

Curves a and 2a show potential level distributions when the laser light is reflected on an ideal photoconductor having a photosensitivity of a specified value.

Curves b, 2b, and 3b show potential level distributions when the charging potential of the photoconductor is 850 V (however, the intensity of laser light is constant) or when the photosensitivity is low.

Curves c and 2c have an inverse relationship to the curve b, and show potential level distributions when the charging potential of the photoconductor is 750 V or when the photosensitivity is high.

In addition, h ₁ , h ₂ , and h ₃ are character line widths (in the case of a normal image), and d ₁ is a scanning pitch of laser light.

As is apparent from FIG. 7, the potential level of the portion irradiated with the laser light fluctuates significantly due to the relationship between the charging potential of the photosensitive member surface and the photosensitivity.

Therefore, for example, when the photosensitivity or the charging characteristic of the photoconductor changes, the apparent spot diameter of the laser beam on the photoconductor changes. Therefore, when the optical sensitivity in the printing apparatus for performing positive development is low, or if the charging characteristic is good, sweep leaves occurs (Seventh Figure notes h portion indicated by _4), or character line would contain horizontal lines in the image The width becomes thicker (h ₁ →
h ₃ ).

Also, if the photosensitivity is high, or if the charging characteristics are poor, the line width of the characters (white, black, or the black part when white) becomes thin (h ₁ → h ₂ ) or disappears. There was a problem that it would end up.

[Prior art]

Conventionally, in order to maintain the uniformity of the image performance of the printed output, use a photosensitive member with less charging deviation and sensitivity deviation, and further adjust the charging strength so that the deviation is corrected, and expose I was adjusting the amount.

FIG. 5 is a diagram showing a schematic configuration of a charger used for adjusting the charging strength, wherein FIG. 5 (a) is a front view and FIG.
(b) is a plan view.

In the figure, reference numeral 18 is a shield case made of an insulating material, and a corona wire 19 is fixed by screws 20 and 21.

Reference numeral 22 is a height adjusting screw for adjusting the height of the corona wire 19, and the tip 22a of the height adjusting screw 22 is used.
Adjust height by pushing up 9.

Reference numerals 23 and 24 are edges for controlling the lateral position of the corona wire 19.

FIG. 6 is a diagram showing the relationship between the height of the corona wire 19 from the photosensitive member and the surface potential. The height adjustment value on the horizontal axis is
The values are shown from a position 10 mm away from the photoconductor.

As shown in the figure, the surface potential changes linearly as the height changes.

In the above-mentioned configuration, the maintenance person, the tester at the time of shipment of the apparatus, or the like while checking the print result
The height of the corona wire was adjusted so that the line width would not change.

Further, also in the adjustment of the exposure amount and the like, an operation such as adjusting the applied voltage by the voltage adjusting volume applied to the light source is performed while observing the printing result.

[Problems to be solved by the invention]

However, when only a photosensitive member having a small deviation in performance is used, the manufacturing yield of the photosensitive member is reduced, the photosensitive member price is increased, and it is difficult to provide an inexpensive printing device. It was Further, adjustment of the charging strength and the exposure amount usually requires a specialist, and the adjustment is very troublesome.

[Means for solving problems]

In view of the above-mentioned conventional problems, the present invention can improve the manufacturing yield of the photoconductor, and can reduce the adjustment of the electrification strength and the like as much as possible. Is provided by means of
The photoconductor is inserted into the electrophotographic printing apparatus and at least one of the charging ability of the charger and the emission intensity of the light emitting source that affects the density of the visible image transferred to the medium is set to Printing is performed using the photoconductor in a state where the photoconductor is assembled and mounted with a predetermined deviation in the longitudinal direction, and when printing is performed using the photoconductor, the difference in gray scale in the longitudinal direction of the photoconductor is performed. In the case where there is any, the electrophotographic printer is inserted by reversing the longitudinal direction of the photoconductor so that the deviation of the characteristics affecting the image quality in the longitudinal direction of the photoconductor is corrected. The method of mounting the photoconductor in.

[Action]

That is, in the present invention, the charging capability of the charger or the light emission intensity of the light emission source is mounted with a predetermined deviation in the axial direction of the photosensitive drum. That is, for example, the height of the corona wire is brought slightly closer to the photosensitive drum side by the above-mentioned adjusting screw during assembly so that the charging voltage on the left side of the photosensitive drum becomes higher.

As a result, even if there is an axial deviation in the characteristics of the photoconductor, since it is mounted in a state in which the charging ability of the pre-charging device has an axial deviation, the mutual deviations are canceled out. Therefore, it is not necessary to correct the density unevenness. In some cases, the deviation of the photoconductor is the same as the deviation of the charger, and the deviation of the characteristics may be synergistic. However, it can be dealt with by reversing the mounting direction of the photoconductor.

In addition, even if there is some deviation in the characteristics of the photoconductor, since there is a difference in the charging ability of the pre-charging band electricity, it is sufficient if the deviation of the photoconductor is within the allowable range from the deviation. The manufacturing yield can be improved.

〔Example〕

Hereinafter, embodiments of a method for mounting a photoconductor in an electrophotographic printing apparatus according to the present invention will be described in detail with reference to the drawings.

FIGS. 1 (a) and 1 (b) are views for explaining an embodiment of the present invention, which is a view for explaining a relationship between a characteristic of a photoconductor and an image.

FIG. 1 (a) is a selenium-tellurium photoconductor used as a photoconductor, and is assembled so that the charging potential is 800V.
Shows a good image area when using a photoconductor that has a left-right deviation in charging performance and sensitivity performance in an ideal electrophotographic device (for example, equivalent to a conventional device) in which all components other than the photoconductor are uniform. In the figure, a shaded area indicated by a symbol A in the figure is a good image area.

In the figure, ΔV represents a charging deviation and ΔE represents a sensitivity deviation.
The deviation is that when the photoconductor is viewed along the axial direction (longitudinal direction) of the photoconductor, the charging performance or photosensitivity at the left end of the photoconductor is different from the charging performance or photosensitivity at the right end of the photoconductor. It shows how much difference there is. The deviation (+) indicates that, in the case of the charging performance (ΔV), the larger the value of +, the higher the charging potential on the left side of the photoconductor is higher than the charging potential on the right side of the photoconductor. In case of (Δ
It is shown that as the values of E) and + increase, the photosensitivity on the left side of the photoconductor becomes lower than the photosensitivity on the right side of the photoconductor. Similarly, the deviation (-) indicates that, in the case of the charging performance (ΔV), the larger the value of-, the lower the charging potential on the left side of the photoconductor is lower than the charging potential on the right side of the photoconductor. In the case of photosensitivity (ΔE), the larger the negative value, the higher the photosensitivity on the left side of the photoconductor is higher than the photosensitivity on the right side of the photoconductor.

Here, the reason why the good image area A is the area of the upper left straight line having a predetermined width is, as is clear from FIG. 1 (a), even if the charging potential on the left side becomes high, the sensitivity is correspondingly increased. If it is good, it is due to sufficient exposure.

The same applies to the opposite case.

That is, as described with reference to FIG. 7, when the charging characteristics are good (the charging potential is high) or the photosensitivity is poor, the potential level distribution on the photoconductor is as shown by the curve b.
Since it is biased to the higher side, it is possible to obtain the potential level distribution shown by the curve a by increasing the amount of light applied to the photoconductor, and in the opposite case by decreasing the amount of light.
An image with a uniform line width can be obtained.

Therefore, as is clear from FIG. 1 (a), in order to prevent a difference in grayscale between the left and right or a change in line width in the image, a photoconductor having a performance such as the good image area A is required. Becomes

Expressing this numerically, | ΔV + 5 × ΔE | ≦ 50 (1) ΔV = V left-V right.

However, in view of the current manufacturing accuracy of the photoconductor, the manufacturing yield is 20 to 3 within the range of the numerical value of the formula (1).
Only 0% can be achieved.

For this reason, for example, if the charging ability of the charger on the left side of the photoconductor is increased by 50 V by the method described in the section of the prior art, the good image area becomes a broken line area indicated by symbol B in FIG. 1 (b). Become.

Now, in this case, at first glance it seems that the image good area of the photoconductor has moved, but when the left and right of the photoconductor is reversed,
The good image area moves to the solid line area indicated by the symbol C in FIG.

Therefore, conventionally, the characteristic within the range of the formula (1) was required, but in the present embodiment, the characteristic within the range of about twice as described above may be used.

This can be expressed by a formula: | ΔV + 5 × ΔE ≦ | 100 (2) However, ΔV and ΔE are the same conditions as in the formula (1).

In the range of the numerical value of the formula (2), the manufacturing yield is about 80%, and the yield is greatly improved.

FIG. 2 is an illustration of a photosensitive drum used in an electrophotographic printing apparatus.

In the figure, 30 is a photosensitive drum made of an aluminum substrate on the surface of which a Se-Te layer is formed, 31 is a left flange that is fitted on the left side of the photosensitive drum 30, 32 is a right flange that is fitted on the right side, and 33 and 34 are left and right. Bolts and nuts (3 sets are used) for fixing the flanges 31 and 32 of the above, and 35 and 36 are bearings, respectively.

The photosensitive drum of the configuration shown in the figure is set by inserting it into the shaft fixed to the device, and the rotation is performed by rotating the left flange 3
This is performed by inserting a not-shown claw member connected to the motor 4a (inserted by setting the photosensitive drum) into D and E in the hollow portion of 1.

Then, by using an electrophotographic printing apparatus in which the charging ability of the charger is 50 V stronger on the left side, a printing operation is performed, and it is confirmed whether or not there is a grayscale difference (change in line width) between the left and right images. To do.

If there is a density difference (change in line width), the apparatus is stopped, the photosensitive drum is removed, and the left and right flanges 31 and 32 are installed in reverse and used.

In this case, since the deviation of the charging ability of the charger is kept in advance, the density difference (change in line width) is emphasized in the case of the photoconductor having the deviation in the opposite direction, which facilitates the determination. Can be done.

The deviation of the charging ability may be reversed.

Furthermore, in the present embodiment, the case has been described in which only the charging ability is allowed to wait for the deviation in advance, but the deviation may be allowed for the emission intensity of the light emitting source. One example is to increase or decrease the laser light amount of the semiconductor laser according to the scanning position.

〔The invention's effect〕

As described above, according to the present invention, the manufacturing yield of the photoconductor can be improved.

Further, since the charging strength may be adjusted only in the case of the photoconductor having a performance outside the range of FIG. 1 (b), the adjustment work can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment, FIG. 2 is an explanatory diagram of a photosensitive drum, FIG. 3 is an overall configuration diagram of an electrophotographic printing apparatus, FIG. 4 is an optical system configuration diagram, and FIG. 6 and 6 are diagrams showing the relationship between the height of the corona wire and the charging potential, and FIG. 7 is a diagram for explaining the change in line width. In the figure, 30 is a photosensitive drum, 31 is a left flange, 3
2 is a right flange, 33 is a bolt, 34 is a nut, 35,
36 is a bearing.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masao Konishi, 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Katsumi Tateno, 1015, Kamikodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Juntaka Aida 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Shoji Yamazaki 1015, Uedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Murata Yuichi, Saitama Shindengen Industrial Co., Ltd. 10-13 Minami-machi, Hanno-shi, Japan (72) Inventor Mitsuhiro Yoshidome 462, Osato-cho, Kofu-shi, Yamanashi Yamanashi Electronics Industrial Co., Ltd.

Claims (1)

[Claims] 1. A photoconductor and a charger for charging the photoconductor.
An electrophotographic system having a light emitting source for exposing a charged photoconductor, a developing device for developing a latent image on the photoconductor, and a transfer means for transferring a visible image developed by the developing device onto a medium. A printing device, wherein the charging ability of the charger, which affects the density of a visible image transferred to the medium by inserting the photoconductor into the electrophotographic printing device, and the emission intensity of the light emitting source At least one of which has a predetermined deviation in the longitudinal direction of the photoconductor, is assembled and mounted, and printing is performed using the photoconductor, and the photoconductor is printed when the photoconductor is used for printing. When there is a density difference in the longitudinal direction of the photoconductor, the longitudinal direction of the photoconductor is inserted so as to be reversed so that the deviation of the characteristics affecting the image quality in the longitudinal direction of the photoconductor is corrected. Mounting method for photoconductor in electrophotographic printer