JP2762726B2 - Electrophotographic process - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic printer which uses a light emitting diode (LED), a semiconductor laser diode (LD) or the like as a light source and uses relatively long wavelength light as exposure light. Related to the electrophotographic process.

[Conventional technology]

As a photoreceptor for electrophotography, such as a light emitting diode and a semiconductor laser diode, which has high sensitivity to light of a relatively long wavelength, a function-separated type Se-Te type having a charge generation layer made of a high Te concentration Se-Te alloy 2. Description of the Related Art Photoconductors (hereinafter, also simply referred to as Se-Te-based photoconductors) are known. Like other Se-based photoreceptors, such Se-Te-based photoreceptors tend to change in properties due to repeated use in physical properties or changes in use environment temperature, and therefore, electrophotography using such a photoreceptor In the process, short-wavelength light having a wavelength of 500 nm or less, which is considered to have relatively little effect on the photosensitive layer, has been used as the neutralization light. However, in recent years, with the improvement in image quality such as print density and resolution of an obtained image, it has been clarified that the above-described static elimination light significantly appears in an image memory in a previous cycle by exposure light. Light having a longer wavelength of 660 nm than in the past has been increasingly used with a weak light amount (about 4 to 10 times the half-attenuated exposure amount of the photoreceptor used).

[Problems to be solved by the invention]

A function-separated type Se-Te with a high Te concentration charge generation layer is used in an electrophotographic process using a light amount of about 4 to 10 times the half-attenuation exposure amount of a photoreceptor that uses light of 600 nm to 660 nm for static elimination light.
Even when a photoreceptor is used, no charge appears on the image where the charge has been successfully removed and the photoreceptor characteristics are relatively stable, but higher quality image quality (more stable high printing In a printer pursuing a high density (high density, high resolution) image, a change in print density due to a decrease in charge (decrease in light area potential) in the initial stage of printing (about several tens of cycles) or a change in print characteristics due to a change in environmental temperature becomes a problem. Is no longer satisfying.

The present invention solves the above-mentioned problems, and a function-separated type Se-Te made of a high Te concentration Se-Te alloy is used as an image forming member in an electrophotographic printer using an LED, LD, or the like as an exposure light source.
Provided is an electrophotographic process capable of suppressing a change in printing characteristics due to a change in print density and a change in environmental temperature at the beginning of printing when using a photoreceptor, and capable of stably obtaining a high-quality image with no memory. It is an issue to be solved.

[Means for solving the problem]

According to the present invention, there is provided an electrophotographic process in which respective steps of charging, image exposure, toner development, toner image transfer, photostatic elimination, and cleaning are sequentially performed on the surface of an electrophotographic photosensitive member as an image forming member. (A) using a function-separated Se-Te type photoreceptor having a photosensitive layer made of a high Te concentration Se-Te alloy as an image forming member; Using light within the range of 660 nm or less. (C) To cause additional pre-fatigue,
After performing several cycles of single-charging irradiation on the photoreceptor with a light amount of 10 times or more the half-attenuation exposure amount at room temperature (22 ° C.) indicated by the photoreceptor of the above item (a) using the charge removing light of item (a) The problem is solved by performing the electrophotographic process.

In the electrophotographic process, it is preferable that the number of cycles of pre-fatigue in the item (c) is changed according to the surface temperature of the photoconductor. Further, in the electrophotographic process, the light elimination light amount in the step of light elimination is within a range of 3 times or more and 7 times or less of the half-attenuated exposure amount at room temperature (22 ° C.) of the photoreceptor described in the above item (a). It is also desirable to change the temperature according to the surface temperature of the photoconductor.

[Action]

Even when a Se-Te type photoreceptor is used as the image forming member, it is possible to prevent a memory from appearing in an image obtained by using light having a wavelength of 600 nm or more and 660 nm or less as static elimination light in the static elimination step.

Factors of initial charge reduction and characteristic fluctuation due to environmental temperature change during repeated continuous use of the Se—Te-based photoreceptor include (A) factors of initial charge reduction and (a) factors from the photoreceptor substrate to the photosensitive layer. Injection of charge (b) Injection of charge from photoconductor surface to photosensitive layer (c) Accumulation of space charge in photosensitive layer (B) Factor of characteristic fluctuation due to environmental temperature change (a) Thermally excited carriers in photosensitive layer Changes in the amount of generation (b) Changes in the mobility of charges in the photosensitive layer (c) Changes in the carrier generation efficiency during exposure in the charge generation layer can be considered, but in the present invention, item (C) of (A) The electrophotographic process was improved by focusing on item (C) of (B). That is, the photoreceptor is subjected to fatigue before repetition of repeated irradiation with one light, accumulates space charges and starts printing, and space charges accumulate after the start of printing shown in (C) of (A). Prevents the phenomenon of charge reduction. It is preferable to use a neutralizing light for light irradiation in the pre-fatigue, and to set the light amount to 10 times or more the half-attenuation exposure amount of the photoconductor at room temperature (22 ° C.). Further, the number of cycles of the pre-fatigue is changed in accordance with the surface temperature of the photoreceptor. , The change in the carrier generation efficiency due to the environmental temperature change in the item (c) of (B) is reduced. In this way, it is possible to suppress the change in characteristics due to the decrease in the charge of the photoconductor at the initial stage of printing and the change in the environmental temperature, the change in the print density at the initial stage is small, and the high image quality is stable even at different environmental temperatures.
In addition, it is possible to obtain an electrophotographic process capable of obtaining an image in which no memory appears.

〔Example〕

FIG. 1 is a schematic cross-sectional view of an example of a function-separated type Se—Te photoconductor used as an image forming member in the electrophotographic process of the present invention, in which a film made of pure Se is formed on a conductive substrate 1 made of Al. 45 μm thick charge transport layer, 0.1 μm thick charge generation layer made of 46% by weight of Se—Te alloy, 1.5% by weight of Se—A
A surface protection layer made of an s alloy and having a thickness of 3 μm is formed by sequentially depositing and depositing a film. FIG. 2 is a conceptual diagram of an example of a machine process of an actual photosensitive member characteristic evaluation apparatus, which is a five-drum photosensitive member, around which a charger 6, a semiconductor laser beam exposure light 7, External potential sensor,
A transfer unit 9, an AC separator 10, a neutralizing light 11 having a wavelength of 600 nm to 660 nm, and a cleaner 12 are arranged at the illustrated angle (equivalent to an actual printer) with respect to the axis of the photoconductor. The light quantity of the static elimination light 11 is variable, and the static elimination light 11 can be used as the pre-fatigue light and combined with the charger 6 to provide the pre-fatigue (variable number of cycles) of the irradiation with one charging light.

With the above-mentioned actual equipment characteristic evaluation device,
The actual characteristics of the Te photoreceptor were evaluated. The half-attenuation exposure amount E1 _{/ 2} of the photoreceptor greatly changes depending on the surface temperature of the photoreceptor, as shown in an example in FIG. Generally, the amount of static elimination is room temperature (22
It is considered that about four times the half-attenuated exposure amount E _1/2 (22 ° C.) at about ₁₀₀ ° C.) is used. Based on this, the surface temperature of the photoreceptor is detected by a thermistor or the like, and recorded in a storage device. The data of the surface temperature of the photoreceptor and the half-attenuated exposure amount described above can be used to set the optimum amount of static elimination at each surface temperature. For example, at a surface temperature of 5 ° C., E _1/2 (22
℃), and about 3 times E _1/2 (22 ℃) at a surface temperature of 40 ℃.
Double is the optimal amount of charge removal.

Next, at room temperature, the pre-fatigue cycle was fixed at 5 cycles, the amount of pre-fatigue light (static elimination light) was changed to give 5 cycles of pre-fatigue, and a series of machine processes of the evaluation apparatus were repeated. When the relationship between the amount of charge decrease (measured by the developing unit potential sensor) and the amount of pre-fatigue light was examined (up to 25 cycles), as shown in FIG.
It was found that the charge reduction was saturated at about 10 times _1/2 (22 ° C.). Therefore, the amount of pre-fatigue light is set to E _1/2 (22 ° C) by 10
The relationship between the surface temperature of the photoreceptor and the number of pre-fatigue cycles required for the initial charge reduction amount to be saturated was determined. The result shown in FIG. 5 was obtained. The data shown in FIGS. 4 and 5 are recorded in a storage device so that the amount of pre-fatigue light and the optimum number of pre-fatigue cycles can be set in accordance with the surface temperature of the photoreceptor. As described above, in the embodiment in which the amount of charge reduction is measured at a position where the amount of pre-fatigue light, the number of pre-fatigue cycles, and the amount of charge elimination are appropriately set in accordance with the surface temperature of the photoreceptor, as shown in FIG. In addition, the charging stability when the surface temperature of the photoconductor is changed is remarkably improved as compared with the conventional comparative example in which the pre-fatigue was not performed and the amount of static electricity removal was fixed at 6 times E _1/2 (22 ° C.). It turned out that.

Based on the above results, using a function-separated Se-Te photoreceptor, data showing the relationship between the half-attenuated exposure amount of the photoreceptor used and the photoreceptor surface temperature recorded in the storage device and the initial time Prints with a semiconductor laser beam printer that sets the pre-fatigue light quantity, pre-fatigue cycle number, and static elimination light quantity appropriately based on the data indicating the relationship between the number of pre-fatigue cycles and the photoconductor surface temperature until the amount of charge reduction saturates. As a result, it was confirmed that a change in print characteristics due to a change in print density and a change in environmental temperature at the beginning of printing was small, and a high-quality image in which no memory appeared was stably obtained.

〔The invention's effect〕

According to the present invention, an electrophotographic process is performed in which light having a wavelength of 600 nm to 660 nm is used as a charge removing light, and pre-fatigue and charge removal are performed in accordance with a half-decay exposure amount of a photoreceptor to be used and an environmental temperature. According to such an electrophotographic process, a function-separated Se-film made of a high Te-concentration Se-Te alloy is used as an image forming member in an electrophotographic printer using an LED, LD or the like as an exposure light source.
When using a Te-based photoreceptor, it is possible to suppress changes in printing characteristics due to changes in print density and environmental temperature at the beginning of printing, and to obtain high-quality images stably without the appearance of memory. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a photoreceptor used in the electrophotographic process of the present invention, FIG. 2 is a conceptual diagram of an example of a machine process of a device for evaluating actual characteristics of a photoreceptor, and FIG. FIG. 4 is a diagram showing an example of the relationship between the surface temperature and the amount of half-decay exposure, and FIG. 4 is a diagram showing an example of the relationship between the amount of pre-fatigue light and the amount of charge reduction up to 25 cycles in the apparatus shown in FIG. FIG. 5 is a diagram showing an example of the relationship between the photoreceptor surface temperature and the number of pre-fatigue cycles until the initial charge reduction amount is saturated in the apparatus shown in FIG. 2, and FIG. 6 is a diagram shown in FIG. FIG. 6 is a diagram showing an example of the relationship between the photoconductor surface temperature and the amount of charge reduction up to 250 cycles in the example and the comparative example in the apparatus in which the present invention is performed. DESCRIPTION OF SYMBOLS 1 ... Conductive substrate, 2 ... Charge transport layer, 3 ... Charge generation layer, 4 ... Surface protective layer, 5 ... Photoconductor, 6 ... Charger,
7 Exposure light, 8 Development section potential sensor, 9 Transfer device, 10 AC separator, 11 Static elimination light, 12 Cleaner.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-256084 (JP, A) JP-A-1-191890 (JP, A) JP-A-64-84284 (JP, A) JP-A-63-63 JP-A-62-246076 (JP, A) JP-A-62-160471 (JP, A) JP-A-1-186991 (JP, A) JP-A-63-101885 (JP, A) JP-A-62-85282 (JP, A) JP-A-60-209753 (JP, A) JP-A-3-67291 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 21/00 345 G03G 21/08 G03G 15/00 303 G03G 5/08 101

Claims (3)

(57) [Claims] 1. An electrophotographic process in which charging, image exposure, toner development, toner image transfer, photostatic elimination, and cleaning are sequentially performed on the surface of an electrophotographic photosensitive member as an image forming member. A function-separated type Se-Te type photoreceptor having a photosensitive layer composed of a high Te concentration Se-Te alloy is used as a forming member. (C) The charge removal light of the item (b) is used to additionally cause pre-fatigue, and the room temperature (22)
An electrophotographic process, wherein the photoreceptor is irradiated with a single light beam for several cycles with an amount of light that is at least 10 times the half-attenuated exposure amount at (° C.), and then the electrophotographic process is performed. 2. The electrophotographic process according to claim 1, wherein the number of cycles of the pre-fatigue in the item (c) is changed by a predetermined value according to the surface temperature of the photosensitive member. 3. The method according to claim 1, wherein the light elimination light quantity in the light erasing step is determined by the method (a).
A predetermined change according to the surface temperature of the photoreceptor within a range of three times to seven times the half-attenuation exposure amount of the photoreceptor at room temperature (22 ° C.). An electrophotographic process according to claim 1.