JPS6049357A - Sensitivity correcting method of photoconductive sensitive body - Google Patents

Abstract

PURPOSE:To correct sensitivity easily and securely by applying the conductive base of a photosensitive body directly and forcibly with a voltage which has the polarity and level corresponding to the sensitivity. CONSTITUTION:The photosensitive body 1 consists of the conductive base 10, photoconductive layer 11, and fixed flanges 12 and 13, and the fixed flanges 12 and 13 are conductors and contact the conductive base 10 directly, so a conductive brush 14 is brought into contact with, for example, the shaft part of the flange 12 to make a connection with a power supply 15, thereby applying the voltage to the conductive base 11 of the photosensitive body 1 directly and forcibly. When the applied voltage is -100V, the sensitivity is increased up to standard designed sensitivity, and when a +70V voltage is applied to the conductive base directly and forcibly, the sensitivity is decreased down to the standard designed sensitivity, so even a defective photosensitive body whose sensitivity is higher or lower than the standard designed sensitivity is usable as a normal photosensitive body.

Description

TECHNICAL FIELD This invention relates to a method for correcting the sensitivity of a photoconductive photoreceptor.

(Prior Art) A photoconductive photoreceptor, which is formed by providing a photoconductive layer on a conductive substrate and is used repeatedly, is well known in connection with visible image transfer type copying devices and printers.

In general, the sensitivity of such photoconductive photoreceptors is determined according to the design conditions when a copying device or printer is designed, and a photoreceptor with the sensitivity determined in this way is manufactured. . However, among the photoreceptors manufactured, there are many whose sensitivity deviates from the designed sensitivity tolerance range. A photoreceptor that does not have the desired sensitivity is
Previously, they were discarded as defective products.

Indeed, the sensitivity of a photoconductive photoreceptor often changes with increasing number of repeated uses when the photoreceptor is used repeatedly. However, in the past, in such cases, the operator of the copying machine, printer, etc. would adjust the photoconductor charging conditions and exposure conditions while looking at the copy, etc., to improve the image quality of the copy due to the sensitivity fluctuation. was correcting for changes in

(Objective) Therefore, the present invention aims to provide a method for correcting the sensitivity of a photoconductive photoreceptor, which can solve such problems.

(composition) The present invention will be explained below.

Before proceeding with the description of the present invention, the meaning of the term sensitivity in this specification will be briefly explained.

Sensitivity in this specification is, needless to say, the sensitivity of a photoconductive photoreceptor, and the light energy E required to reduce the surface potential of the photoreceptor by half is used as an index to evaluate this sensitivity. . That is, the photoreceptor is set to a predetermined surface potential Vi
After being charged to a certain level, the light energy E required for the surface potential to brightly attenuate from vi to surface potential +Vi by light irradiation for a certain period of time T is used as an index of sensitivity. Various other indicators can be considered.

Using this index E, the smaller E is, the higher the photosensitivity of the photoreceptor is. In this specification, such a highly sensitive photoreceptor is referred to as a highly sensitive photoreceptor. Conversely, a photoreceptor with low sensitivity is called a slow-sensitivity photoreceptor.

Further, by the sensitivity correction method according to the present invention, decreasing the index E is said to increase the sensitivity, and the opposite case is referred to as decreasing the sensitivity.

Now, the features of the present invention are as follows.

That is, a voltage having a polarity and magnitude corresponding to the sensitivity is forcibly applied directly to the conductive substrate of the photoreceptor.

If the sensitivity of the photoreceptor fluctuates as the number of repetitions increases during repeated use of the photoreceptor, the voltage directly and forcibly applied to the conductive substrate is changed in accordance with the fluctuations in the sensitivity of the photoreceptor. . In this case, since the sensitivity variation is generally determined as a characteristic, the voltage variation corresponding to the sensitivity variation can be programmed in advance and automatically performed.

The polarity of the voltage applied to the conductive substrate is determined by whether the sensitivity of the photoreceptor is increased or decreased. Generally, when a voltage with the same polarity as the charged polarity of the photoreceptor is applied to a conductive substrate,
Sensitivity becomes slower. Conversely, if a voltage with a polarity opposite to that of the photoreceptor is applied to the conductive substrate, the sensitivity becomes faster.

For example, in the case of a Se-based photoreceptor whose charging polarity is positive, the sensitivity can be slowed down by applying a positive voltage to the conductive substrate, and the sensitivity can be stopped by applying a negative voltage. Conversely, in the case of a photoconductor with negative charging polarity, such as an OPC photoconductor, the sensitivity can be slowed down by applying a negative voltage to the conductive substrate, and the sensitivity can be increased by applying a positive voltage. It can be sped up.

Furthermore, the magnitude of the applied voltage determines how much the sensitivity is slowed down or speeded up.

The relationship between the magnitude of the applied voltage and the magnitude of the change in sensitivity is generally not a linear relationship, but is generally as shown in FIG. The horizontal axis in FIG. 1 represents the absolute value of the voltage applied to the conductive substrate of the photoreceptor, and the broken line represents the relationship between the applied voltage and the change in sensitivity when the applied voltage and the photoreceptor charging polarity are the same. Further, a solid curve shows a change in sensitivity due to an applied voltage when the applied voltage and the polarity of the photoreceptor are opposite in polarity.

Therefore, when the sensitivity correction method of the present invention is used, photoconductors with sensitivity that are too fast or too slow relative to the standard design sensitivity value, which were conventionally discarded as defective products, can be replaced with photoconductors that have standard design sensitivity by sensitivity correction. It can be used as a body.

Let me give you a concrete example of this.

The circumferential surface of the aluminum drum is super-finished, and on the circumferential surface,
Let us take as an example a photoreceptor in which 380 layers containing Te and C1 are formed to a predetermined thickness.

The sensitivity of these photoreceptors was measured using the sensitivity index described above, and from among them, those having sensitivities that deviated from the appropriate sensitivity value for copying machine design (hereinafter referred to as standard design sensitivity) were selected.

First, a photoreceptor with a sensitivity lower than the standard design sensitivity was incorporated into a copying machine. The copying device is of a magnetic bluff development type and a visible image transfer type. FIG. 2 schematically shows the main parts of this copying apparatus.

In the figure, 1 is a photoreceptor, 2 is a charger, 3 is a magnetic brush developing device, 4 is a paper feed cassette, and 40 is a paper feed roller. , 5 is a transfer charger, 6 is a separation roller, 7 is a cleaning device, 8 is a
The fixing device and reference numeral 9 indicate a static eliminator. The static eliminator 9 has a voltage of 4KV.

This is an AC corona static eliminator of 3μA/cm.

During copying, the photoreceptor 1 rotates in the direction of the arrow.

The rotating photoconductor 1 is first cleaned by a cleaning device 7, neutralized by a static eliminator 9, and then uniformly positively charged by a charger 2 (the photoconductor 1 is Se-based).
. Next, the electrostatic latent image formed by image exposure by the image exposure light flux is visualized by the developing device 3. In synchronization with the movement of the visible image obtained in this way, the recording paper S is fed by the paper feed roller 40 and sent to the transfer section, that is, between the photoreceptor 1 and the transfer charger 5, and is transferred to the transfer section. Superimposed on the visual image.

The visible image on the photoreceptor 1 is electrostatically transferred onto the recording paper S by a transfer charger 5, separated from the photoreceptor 1 by a separation charger 6, and fixed by a fixing device 8, and then copied. is discharged from the device as After the visible image has been transferred, the photoreceptor 1 is cleaned by a cleaning device to remove residual l.
The static electricity is removed by the static eliminator 9.

Now, a photoreceptor whose sensitivity is too slow compared to the standard design sensitivity was incorporated into the apparatus as photoreceptor 1.

The copying apparatus shown in FIG. 2 has copying conditions set in accordance with a photoreceptor having a standard design sensitivity.

Therefore, when copying was carried out using the above-mentioned photoreceptor with low sensitivity, the obtained copy image was darkened as a whole. This is because the sensitivity of the photoreceptor is slower than the standard design sensitivity, so development is performed in a state where the potential of the light irradiation area is not sufficiently attenuated after image exposure.

Now, the photoreceptor 1 has a structure as shown in FIG. In the figure, numeral 10 is a conductive substrate, numeral 11 is a photoconductive layer,
Reference numerals 12 and 13 indicate fixed flanges, respectively.

The fixed flange 12.13 is an electrical conductor and is in direct contact with the electrically conductive substrate 10. Therefore, for example, as shown in FIG. 3, if the conductive brush 14 is brought into contact with the shaft of the flange 12 and the conductive brush 14 is connected to the power supply 15, the conductive base 11 of the photoreceptor 1 can be directly contacted. And voltage can be forcibly applied.

Therefore, the above-mentioned photoreceptor was once removed from the copying machine, and a negative voltage was directly and forcibly applied to the conductive substrate using the method shown in Fig. 3. While evaluating the sensitivity, the applied negative voltage was As a result of adjustment, when the applied voltage was set to -ioov, the sensitivity was increased to the standard design sensitivity.

Therefore, the above-mentioned photoreceptor was installed in the copying machine once again.
When copying was performed by the method shown in FIG. 3 while applying 100 V to the conductive substrate, the entire darkening in the copy image described above was removed and a normal and good copy image was obtained.

Similar experiments were conducted with photoreceptors that were too sensitive. When copying was performed without editing and without performing sensitivity correction, the resulting copied image lacked halftone density. This is because the brightness attenuation is too fast, and the potential of the latent image in the halftone area is attenuated too much at the time of development.

It was found that by directly and forcibly applying a voltage of +70V to the conductive substrate, it was possible to delay the sensitivity to the standard design.When copying was carried out with a voltage of +70V applied, half-tone A normal copy image with good reproducibility was obtained.

In this way, by using the sensitivity correction method of the present invention, even a defective photoreceptor whose sensitivity is too slow or too fast than the standard design sensitivity can be used as a normal photoreceptor.

The above is a case in which the apparent sensitivity is normalized by correcting the sensitivity of a photoconductor that originally has abnormal sensitivity, but the sensitivity correction of the present invention changes the sensitivity of the photoconductor, It may also be used to change the image quality of i-images according to preference.

By the way, photoconductive photoreceptors that are used repeatedly can be classified into the following three categories based on sensitivity.

In other words, in the first type, the sensitivity is stabilized by applying corona discharge and strong exposure immediately after vapor deposition, so that the sensitivity of the photoreceptor does not change with the number of repetitions, except for the initial few times during continuous repeated use. The second type is one in which the sensitivity becomes slower as the number of repetitions increases, and the third type is one in which the sensitivity becomes faster as the number of repetitions increases.

As the first type, a 5e-As type photoreceptor can be used. For example, we investigated photoreceptors in which the peripheral surface of an aluminum drum was superfinished and a photoconductive layer of AS2S,3 was vacuum-deposited on the peripheral surface to a predetermined thickness. When used repeatedly, except for the very first 1 or 2 times,
No change in sensitivity was observed with the number of doses.

Therefore, in this type of photoreceptor, except for the first one or two cycles, a voltage of polarity and magnitude corresponding to the sensitivity is directly and forcibly applied to the conductive substrate to correct the sensitivity, and then this applied voltage is applied directly and forcibly to the conductive substrate. If the polarity and magnitude of the voltage are fixed, the sensitivity will always remain at the corrected sensitivity. For the first one or two cycles, charging, exposure, and quenching are performed without paper passing before making a copy, and the subsequent cycles can be ignored.

As the second type of photoreceptor, for example, an Sg layer and a Se
A 5e-Te photoreceptor with a Te layer can produce nine beads. Further, as the third type of photoreceptor, f1]eha,
For example, a 5e-Te photoreceptor may be used, which contains norogen.

These second. If the third type of photoreceptor is used continuously without any break, the sensitivity will change as the number of repeated uses increases, so in order to compensate for this and maintain the sensitivity within an appropriate range during repeated use. In order to correct the sensitivity, it is necessary to change the voltage itself that is directly and forcibly applied to the conductive substrate in accordance with changes in sensitivity.

In this case, various methods can be considered for changing the applied voltage. For example, if the photoreceptor is used continuously without any break, and its sensitivity changes as shown by curve 4-1 in Figure 4 (1) with the number of repeated uses, in this case, the applied voltage It is ideal for sensitivity correction to change as shown by curve 4-2 in FIG. 4 Ql) in correspondence with the sensitivity change 4-1. Of course, such ideal sensitivity correction is also possible. However, from a practical standpoint, as shown in Figure 4(m),
Either change the applied voltage according to the broken line 4-3 that approximates the curve 4-2, or change the applied voltage according to the curve 4-3 as shown in FIG. 4 (1v).
Even if the applied voltage is changed according to step #4-4 close to -2, sensitivity can be sufficiently optimized.

This will be explained below using a specific example.

The circumferential surface of the aluminum drum is super-finished, and S is applied on this circumferential surface.
A layer of 5e-Te containing Te was deposited on the SC layer to a predetermined thickness. The photoreceptor thus obtained was found to have a sensitivity slightly slower than the standard design sensitivity, so it was incorporated into a copying machine as shown in Figure 2, and adjusted to a sensitivity slightly slower than the design sensitivity. and set the copy conditions.

Continuous copying was performed by grounding an aluminum drum as a conductive substrate. Assuming that one copying process is the number of times the photoreceptor is used, as the number of times it is used increases, the sensitivity gradually slows down as shown by curve 5-1 in FIG.
Correspondingly, the resulting copied image also gradually became darker, and a phenomenon called afterimage, in which the image of a previous copy is duplicated on a new copy, occurred.

Therefore, starting from the beginning of repeated use, after time TJ, when the sensitivity slowed down to a certain value, a voltage of 120 cm was applied to the conductive substrate, and the sensitivity was able to return to the initial sensitivity. . After another 12 hours, the sensitivity reached the above-mentioned value again, so the applied voltage was further increased by -20
When I added V to -40V, the sensitivity returned to the initial sensitivity again.

Thereafter, in the same manner, the applied voltage was added by 20 V at a time when the sensitivity reached the above-mentioned certain value. As a result, the change in sensitivity was as shown by the serrated curve 5-2 in FIG.

Further, when the number of repeated uses was 300 times or more, there was almost no change in sensitivity while the applied voltage for sensitivity correction remained fixed. This is because the sensitivity changes are compatible.

In addition, the magnitude relationship of time TI+ T2+ T3+...Ti... is Tz < T2 < T3 <・Tiku・
・It became. In this case, the applied voltage was increased stepwise, and each step of the voltage application step was set at -20V.

However, every time the number of uses increases by a certain number of times, in other words, at a certain time interval, the applied voltage is changed to "It"2+ ・
, Vz, . . . may be controlled to increase sequentially. In this case, IVII>1V2-Vll>
The relationship is lV3 V21')->lVz+t-vil'>.

Next, the peripheral surface of the aluminum drum is superfinished to make it a conductive substrate, and a Se-'reO layer containing Te and doped with Ct is placed on the peripheral surface in a vacuum to a predetermined thickness. It was formed by vapor deposition. This photoreceptor exhibited a slightly slower sensitivity than the standard design sensitivity. This photoreceptor was incorporated as photoreceptor 1 into an apparatus as shown in FIG. 2, and copying conditions were set in accordance with the slightly slow sensitivity described above.

When continuous copying was performed with the conductive base of the photoreceptor grounded, that is, without sensitivity correction, as the number of times the photoreceptor was used increased, the sensitivity gradually became faster and the density of the halftone area gradually decreased. It was observed that it was decreasing. In the measurements, the sensitivity became faster and saturated at a certain predetermined sensitivity.

Therefore, an attempt was made to correct the sensitivity using the same method as explained in the example shown in FIG. That is, with the sensitivity increasing to a slightly lower sensitivity than the above-mentioned saturation sensitivity, +65
When V was applied, the sensitivity recovered to the initial sensitivity again. Hereinafter, by increasing the applied voltage in increments of +60V as the sensitivity speeds up at the above-mentioned sensitivity, which is slightly slower than the saturation sensitivity, the photoreceptor sensitivity will be approximately adjusted to the initial sensitivity and the sensitivity which is slightly slower than the saturation sensitivity. The quality of the resulting copied images was stable and normal.

Next, on the circumferential surface of the aluminum drum, which has a super-finished circumferential surface,
A 5e-Te0 layer containing TC and doped with iodine I was deposited to a predetermined thickness to form a photoconductive layer. In sensitivity evaluation,
Since the sensitivity was slightly slower than the standard design sensitivity, it was installed as photoreceptor 1 in a copying apparatus as shown in FIG. 2, and copying conditions were set according to the sensitivity, which was slightly slower than the standard design sensitivity.

In continuous copying without sensitivity correction, as the number of times the photoreceptor was used increased, the sensitivity became slower, reached a certain value at approximately 60 times of use, and then stably maintained that sensitivity.

Therefore, when the sensitivity reaches the above-mentioned sensitivity where it becomes stable, -1
When a voltage of 20 ■ was directly and forcibly applied to the conductive substrate, the sensitivity recovered to the initial sensitivity, and thereafter, with the applied voltage fixed, the initial sensitivity was maintained throughout continuous copying. I was able to do that. At this time, although the negative voltage is applied by direct current, the same effect as the negative voltage can be obtained by applying an alternating current voltage.

Next, on the circumferential surface of the aluminum drum, which has a super-finished circumferential surface,
A 5e-Te0 layer containing Se and doped with ct was deposited to a predetermined thickness.

This photoreceptor exhibited standard design sensitivity.

The photoreceptor 1 was installed in the photocopying apparatus shown in FIG. 2, and the copying conditions were set in accordance with the standard design sensitivity.

Under conditions where the sensitivity was not corrected, it was observed that during continuous copying, the sensitivity gradually became faster as the number of times the photoreceptor was used increased.

Therefore, while performing continuous copying, when the photoreceptor was used 50 times, +40V was applied to the aluminum drum, which is the conductive base.
When applied, the sensitivity returned to the initial sensitivity. Thereafter, as the number of times the photoreceptor was used increased, the sensitivity became faster again, so when the applied voltage was increased to +90V after 150 uses, the sensitivity returned to the initial sensitivity.

Thereafter, the applied voltage was fixed at +90 V, but thereafter the sensitivity maintained almost the initial sensitivity, and good copies were obtained despite continuous copying.

Incidentally, in the case of a copying apparatus, a situation may occur in which the sensitivity of the photoreceptor appears to have changed even though there is no change in the sensitivity of the photoreceptor or the body itself. This is a case where the amount of light emitted from the illumination lamp used to illuminate the document changes.

The amount of light emitted from halogen lamps and fluorescent lamps, which are commonly used as illumination lamps, is not always constant and often changes over time. For example, in the case of a halogen lamp, the amount of light emitted generally decreases as the usage time increases, and then the amount of light emitted suddenly recovers and remains in the recovery state for a while, before reaching the end of the lamp's lifespan. There are many changes in the amount of light emitted in a pattern called "Meeting".

When the amount of light emitted from the illumination lamp changes in this way, the amount of light exposed to the photoreceptor changes, resulting in a phenomenon as if the sensitivity of the photoreceptor itself had changed.

That is, when the amount of emitted light decreases, the amount of exposure light decreases, so the sensitivity of the photoreceptor becomes apparently slower, and when the amount of emitted light increases, the sensitivity apparently becomes faster.

The sensitivity correction method of the present invention is of course effective in correcting such apparent sensitivity changes.

That is, by treating the apparent change in sensitivity as described above as an actual change in sensitivity and performing the sensitivity correction of the present invention, the apparent 1 degree can be controlled.

(Effects) As described above, according to the present invention, it is possible to provide a method for easily and reliably correcting the sensitivity of a photoconductive photoreceptor.

By correcting the sensitivity using this method, even a defective photoreceptor whose original sensitivity deviates from the designed sensitivity can be used as a normal photoreceptor.

In addition, it is possible to easily deal with sensitivity fluctuations caused by continuous use of the photoreceptor, and copying and the like can always be performed with good sensitivity. Furthermore, when a copying machine is used moderately during the day in an office, etc., the photoreceptor becomes moderately fatigued, and this sensitivity can be corrected to the optimal value, but if the photoreceptor is left to rest for a while, the photoreceptor becomes dark-adaptive. Generally, the sensitivity becomes slower and the image may become darker the next time you use it (especially at the start). Such an initial image can also be corrected only in abnormal situations by applying voltage.

Furthermore, it is possible to easily correct for apparent sensitivity fluctuations due to fluctuations in the amount of light emitted by the illumination lamp, apparent sensitivity fluctuations due to changes in photoreceptor temperature, and sensitivity fluctuations due to dark adaptation. A duplicate image can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the voltage applied to the conductive substrate of the photoreceptor and the general tendency of sensitivity change due to the application of the voltage. Figure 2 is a copying apparatus using a photoconductive photoreceptor. FIGS. 3 to 5 are explanatory front views schematically showing only essential parts of an example of the present invention. ■... Photoreceptor, 1o. Aluminum drum (conductive substrate), 11.. Photoconductive layer, 12.13.. Fixed 7'5r.
), 14. Conductive brush, 15. Power supply.

Claims (1)

[Scope of Claims] 1. A method for correcting the sensitivity of a photoconductive photoreceptor that is used repeatedly without providing a photoconductive layer on the conductive substrate, the method comprising: A sensitivity correction method comprising: forcibly applying a voltage having a polarity and magnitude corresponding to the sensitivity of the photoreceptor. 2. In claim 1, the voltage directly and forcibly applied to the conductive substrate of the photoreceptor is used to increase the sensitivity of the photoreceptor, which changes with the increase in the number of repeated uses, when the photoreceptor is used repeatedly. A sensitivity correction method characterized by being able to be changed accordingly.