JPS6136784A - Cleaning exposure method - Google Patents

Abstract

PURPOSE:To perform repeatedly photographic image forming process by using the light having a wavelength band approximately equal to the sensitivity wavelength band peculiar to a photoconductor in the cleaning exposure where the electric charge remaining on electrophotographic sensitive materials subjected to coloring matter sensitization is removed. CONSTITUTION:For example, a poly-N-vinylcarbazole film is wound around a rotating durm 1, and its surface is electrified negatively by a corona charger 5 each time when the rotating drum 1 is rotated once. At this time, a photosensitive material film 15 is grounded through the rotating drum 1. This electrified photosensitive material film 15 is exposed through a SELFOC lens array 7 by a CRT scanner 6 to which R, G, and B picture signals are given successively. Developing devices 8-10 are moved to developable positions successively to develop the film 15 with individual color toners, and a color image is obtained by three rotations of the rotating drum 1. When a fluorescent discharge tube is used as a cleaning exposure device 14, three-color signals are subjected to exposure in the same level to obtain the color image of good color balance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cleaning exposure method performed to remove residual charges when electrophotographic light-sensitive materials are used repeatedly. The present invention relates to an improvement in a cleaning exposure method for electrophotographic materials that are sensitive and have large internal traps.

[Conventional technology]

Generally, when obtaining an image by an electrophotographic process,
Electrophotographic materials are often used continuously and repeatedly. For example, so-called PPC, which electrostatically transfers a toner image on an electrophotographic light-sensitive material to another paper or film surface.
A typical example is multiple copies under the Act. Further, when forming a color image, the image forming process is not limited to the above-mentioned method, and the image forming process is repeatedly performed on the electrophotographic light-sensitive material. Electrophotographic materials can only be used once.
This is about the same as when a black and white image is obtained in a method in which a toner image is directly fixed onto the surface of the photosensitive material.

When using an electrophotographic light-sensitive material nine times in this way, the light-sensitive material is charged and exposed.

Each development process cycle is repeated, and when moving on to the next cycle, the residual charge remaining on the photosensitive material from the previous cycle has an adverse effect, causing uneven density and abnormal color balance. There is a risk.

For this reason, conventionally, before moving on to the next cycle, it is common to perform so-called cleaning/g exposure on one photosensitive material by applying strong vibration light using a tungsten lamp, halogen lamp, etc. to remove the residual charge. .

However, when using a photosensitive material that tends to have deep traps, such as an electrophotographic material in which a photoconductive layer is formed from a photoconductor sensitized with a sensitizing dye, the cleaning exposure described above is difficult. When exposed to light, a phenomenon called the so-called memory effect occurs because carriers are trapped in a deep drag and require a short time lag to come out. There is a risk of adverse effects such as a decrease in sensitivity and a change in sensitivity.

In this way, the above-mentioned cleaning exposure is necessary when electrophotographic light-sensitive materials are used repeatedly, but when using this type of light-sensitive materials, strong exposure may cause other adverse effects. There is sex.

Therefore, as a method to prevent the negative effects of the above-mentioned cleaning exposure, it is possible to remove the residual charge by applying weak exposure for a long time instead of strong exposure, but this may be a major hindrance to speeding up image formation. Furthermore, there is a need for further improvement in the above-mentioned cleaning exposure method, particularly in cases where a sufficient residual removal effect cannot be obtained unless strong exposure is used, such as in the case of photoconductors such as organic semiconductors.

[Problem that the invention seeks to solve]

Therefore, the present invention has been proposed in response to the above-mentioned needs in the technical field, and it is possible to eliminate the negative effects on image formation in the post-process and quickly remove residual charges, thereby reducing the need for leaning exposure. The purpose is to provide a method.

[Means to solve all problems]

As a result of intensive research in order to develop a leaning exposure method that does not cause the memory effect, the present inventor avoided light at wavelengths absorbed by sensitizing dyes and used light at wavelengths unique to photoconductors to which they are sensitive. Obtained the knowledge that by removing residual charges, it is possible to perform cleaning/g exposure without affecting the traps of the sensitizing dye, despite strong exposure and short exposure. reached.

The present invention was made based on such findings, and is directed to an electrophotographic photosensitive material in which a photoconductive layer is formed of a dye-sensitized photoconductor. This means that the amount of light in the wavelength range that substantially matches the wavelength range is very small.

In general, zinc oxide, titanium oxide, poly-N-vinylcarbazole, and other photoconductor wires used in electrophotographic photosensitive materials each have their own specific wavelength range of sensitivity, and when used alone, they are only sensitive to ultraviolet light pressure. There are many things that are not shown. For example, Figure 1 shows the spectral sensitivity characteristics of zinc oxide, and Figure 2 shows the spectral sensitivity characteristics of poly-N-vinylcarbazole. Both of these photoconductors are sensitive only to wavelengths of 400 nm or less. It can be seen that it has sensitivity.

Therefore, when the above-mentioned photoconductor is used in an electrophotographic light-sensitive material, a sensitizing dye having a spectral absorption as shown in FIG. 3, such as a xanthine-based dye, is usually used.

=r Spectral sensitization is performed using dyes such as xonol, biryllium, and cyanine. By adding the sensitizing dye in this way, the photoconductor becomes sensitive to the absorption wavelength range of the dye, as shown in FIG.

By the way, as shown in FIG. 5, the photoconductor which has been dye-sensitized with the sensitizing dye as described above is subjected to strong exposure using tungsten light having a strong spectral energy distribution over 400 nm, and then subjected to cleaning exposure. A memory effect occurs because the sensitizing dye has deep traps inside, and carriers are likely to be caught in the traps of this dye.

Therefore, in the present invention, cleaning exposure is performed using light that does not have an energy distribution in the absorption wavelength range of the sensitizing dye and has an energy distribution only in a wavelength range that substantially coincides with the photoconductor's unique photosensitive wavelength range. be. That is, for example, zinc oxide and poly-N-vinylcarbazole,
As shown in Figure 1 or 2, it is sensitive only to wavelengths of 400 nm or less, so electrophotographic materials using this type of photoconductor are sensitive to ultraviolet light as shown in Figure 6. Cleaning exposure is performed by performing strong exposure using water lamp light that has a strong spectral energy distribution in the area.

In this way, cleaning exposure is performed using light that does not have a spectral energy distribution in the absorption wavelength range of the sensitizing dye, but has a spectral energy distribution only in the wavelength range that approximately matches the photoconductor's unique photosensitive wavelength range. Even with strong exposure, it is possible to remove residual charges from the sensitizing dye.

[Effect]

As mentioned above, an electrophotographic photosensitive material in which a photoconductive layer is formed of a dye-sensitized photoconductor is exposed to light in a wavelength range that substantially matches the sensitivity wavelength range specific to the photoconductor. Without affecting the sensitizing dye,
In other words, the residual charge on the electrophotographic light-sensitive material is quickly removed without causing a memory sound effect.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.
It goes without saying that the present invention is not limited to these Examples.

Example 1 Poly-N rubinylcarbazole 102. Polycarbonate resin 27 and a sensitizing dye represented by the following formula (pentamethyl//anine dye)9.
05r'i dichloroethane 10 (1', chloroform 1
Thoroughly dissolve and mix with a mixed solvent of ITO (ind.
Using a bar coater, the mixture was applied onto a polyethylene terephthalate film on which a (Tin Qxide) electrode was vapor-deposited, and dried to form a photoconductive layer with a thickness of 8 μm to obtain an electrophotographic photosensitive material.

The obtained photosensitive material was divided into two parts, and the charging characteristics of each part were measured. This charging characteristic is determined by first charging the photosensitive material at +6KV for 3 seconds in the dark, and then
After leaving it in a dark place for 10 seconds, it was irradiated with 7 tux light for 10 seconds, and finally a cleaning exposure was performed, and the above cycle was repeated again, and the change in surface potential of the electrophotographic material at this time was examined. Further, one of the divided electrophotographic materials was subjected to tungsten light exposure (equivalent to about 10,000/m) using a halogen lamp as the cleaning exposure, and the other electrophotographic material was subjected to tungsten light exposure (equivalent to about 10,000/m) as the cleaning exposure. Toshiba Rikagaku Mercury Lamp H400P
) using ultraviolet light (light intensity equivalent to tungsten light)
I did this. The results are shown in FIGS. 7 and 8, respectively.

As a result, when the cleaning exposure was performed using a nitrogen lamp, as shown in Figure 7, a dust memory effect was observed in which both the charged potential and the sensitivity changed after the cleaning exposure. When this was carried out using a mercury lamp, as shown in FIG. 8, even after the cleaning exposure, the charging characteristics were 11 times the same as those of the first exposure, and no memory effect was observed.

Example 2 An electrophotographic image forming apparatus as shown in FIG. 9 was manufactured.

This electrophotographic image forming apparatus includes a rotating drum 1°, a film presser 2, 3 that presses down an electrophotographic photosensitive material film (described later) when the film is wound around the rotating drum IK.
．． Film guide for inserting film 4. Corona charger (-7KV) 5, CRT light:/XXcar-R, G, B,) signals are sequentially switched and applied. )6. SELFOC lens array 7, developing devices 8, 9 movable in the X direction in the figure and movable in the Y direction below the rotating drum 1.
．． 10 (These developing devices 8, 9, and 10 are supplied with yellow wet type toner 11, macenta color wet type toner 12, and Ansen type toner 13, respectively.)
, and a cleaning exposure device 14. Then, the electrophotographic light-sensitive material film 15 (a brominated poly-N-vinylcarbazole film spectrally sensitized over the entire visible light region with two types of cyanine dyes) inserted from the film guide 4 is first rotated. It is wound around the drum 1, and its surface is negatively charged by the corona charger 5 every time the rotating drum 1 rotates once. In addition,
At this time, the photosensitive material film 15 is grounded via the rotating drum 1. Next, this charged photosensitive material film 15 is exposed through the Selfoc lens array T by a CRT scanner 6 to which R, G, and B signals are sequentially applied. Furthermore, the developing device 8
.

When using the above-mentioned apparatus and replacing the cleaning exposure device 14 with a halogen lamp (tungsten light) and a fluorescent discharge tube (short wavelength region light), the entire image was formed.
11, R, G, B, using all halogen lamps in the cleaning exposure device 14.

Under the condition that the level of each signal is the same (the exposure level of the three colors is the same), the color balance is distorted due to the influence of the memory effect, and a good color image cannot be obtained. When using this method, a color image with good color balance could be obtained by exposing three color signals at the same level.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
When performing cleaning exposure to remove residual charges on a dye-sensitized electrophotographic light-sensitive material, avoid light with a wavelength that is absorbed by the sensitizing dye. Because the process uses short-wavelength light (such as ultraviolet light), it does not cause memory effects even though strong vibration light is applied. It is possible to do it repeatedly.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the spectral sensitivity characteristics of zinc oxide, FIG. 2 is a characteristic diagram showing the spectral sensitivity characteristics of poly-N-vinylcarbazole, and FIG. 3 is a characteristic diagram showing the spectral absorption characteristics of sensitizing dye. Figure 4 is a characteristic diagram showing the spectral sensitivity characteristics of dye-sensitized poly-N-vinylcarbazole, Figure 5 is a characteristic diagram showing the spectral energy distribution of tungsten light, and Figure 6 is a characteristic diagram showing the spectral energy distribution of mercury lamp light. It is a characteristic diagram. 7 and 8 show examples of differences in charging characteristics due to differences in cleaning exposure. FIG. 7 is a characteristic diagram showing charging characteristics when cleaning exposure is performed using a halogen lamp; FIG. 8 is a characteristic diagram showing charging characteristics when cleaning exposure is performed using a mercury lamp. FIG. 9 is a schematic cross-sectional view showing the structure of an electrophotographic image forming apparatus used in an embodiment of the present invention. 1.Rotating drum 5.Corona charger 6.CRT scanner 8.9.10.Developing device 14.Cleaning and exposure device 15.Electrophotographic photosensitive material film Fig. 1 Fig. 2 Gas solution L~ Figure 3 Figure 4

Claims (1)

[Claims] It is characterized in that an electrophotographic light-sensitive material in which a photoconductive layer is formed of a dye-sensitized photoconductor is exposed to light in a wavelength range that substantially coincides with the inherent sensitivity wavelength range of the photoconductor. Cleaning exposure method.