JP2018049129A - Electrophotographic recording device, and electrophotographic recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic recording technique that enables images of high definition to be formed even when using toner large in a particle size.SOLUTION: An electrophotographic recording device according to the present invention comprises: a photoreceptor 521; a charge device 523 that contacts with a surface of the photoreceptor 521, and applies an undulating voltage in which an inter-peak voltage Vfalls within a range of 1.7 to 2.0 times an absolute value of a charging start voltage Vof the photoreceptor 521 to the photoreceptor 521, and charges the surface thereof; an exposure device that irradiates the charged surface with light to form an electrostatic latent image; a developing device 52 that supplies to the surface having the electrostatic latent image formed toner in which a median diameter D50 of a volume reference to be obtained by a flow type image analysis method falls within a range of 25 to 50 μm, and forms a toner image corresponding to the electrostatic latent image on the surface; and a transfer device that transfers the toner image to a recording medium from the surface.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrophotographic recording technique.

  An electrophotographic recording technique is sometimes used to form an image on a cloth such as clothing. In such an image forming process, in addition to a normal image forming toner, a thermoplastic resin powder toner having flexibility and binding properties in a normal use temperature range such as clothing is used.

  The thermoplastic resin powder toner is for adhering the image forming toner to the fabric. Therefore, in this image forming process, a certain amount of thermoplastic resin powder toner needs to be present on the fabric in order to sufficiently bond the image forming toner. That is, in order to form an image on a fabric using electrophotographic technology, an amount of thermoplastic resin powder toner sufficient for adhesion of the image forming toner must be developed, transferred, and fixed.

  In addition, since this thermoplastic resin powder toner is flexible, it is difficult to pulverize normally during production. Therefore, the particle diameter of the image forming toner (volume-based median diameter D50 obtained by flow image analysis method; hereinafter the same) is about 10 μm, whereas the thermoplastic resin powder toner is 25 to 50 μm. It has a large particle size.

  By the way, in the image forming process by electrophotography, it is necessary to charge the surface of the photoreceptor to a certain surface potential before forming the electrostatic latent image. If the surface potential on the photoconductor immediately after charging is non-uniform, the amount of toner adhering to the surface of the photoconductor varies due to this. Therefore, it is important to uniformly charge the entire photoconductor.

In Patent Document 1, a pulsating flow having a peak-to-peak voltage V _pp of not less than twice the charging start voltage of the photosensitive member is employed in a conductive member that is in contact with the surface of the photosensitive member in order to charge the surface of the photosensitive member. Application of a voltage is described. Patent Document 1 describes that according to such a method, the surface of the photoreceptor can be uniformly charged.

Japanese Patent Laid-Open No. 05-011571

  The present inventors have found that when a toner having a large particle size is used for charging by the contact charging method described above, the image is blurred.

  An object of the present invention is to provide an electrophotographic recording technique capable of forming a high-quality image even when a toner having a large particle diameter is used.

According to the first aspect of the present invention, the photosensitive member is in contact with the surface of the photosensitive member, and the peak _-to- peak voltage V _p-p is 1.7 to 2.2. The absolute value of the charging start voltage V _th of the photosensitive member. Applying a pulsating voltage within a range of 0 times to the photoconductor to charge the surface and exposing the charged surface to light to form an electrostatic latent image on the surface A toner having a volume-based median diameter D50 obtained by a flow image analysis method in a range of 25 to 50 μm is supplied to the surface and the surface on which the electrostatic latent image is formed. An electrophotographic recording apparatus comprising a developing unit that forms a toner image corresponding to the above on the surface and a transfer unit that transfers the toner image from the surface to a recording medium is provided.

According to the second aspect of the present invention, a pulsating voltage in which the peak _-to- peak voltage _Vp-p is within a range of 1.7 to 2.0 times the absolute value of the charging start voltage _Vth of the photoconductor is obtained by a contact method. Applying to the photoreceptor to charge the surface of the photoreceptor, irradiating the charged surface with light to form an electrostatic latent image on the surface, and forming the electrostatic latent image A toner having a volume-based median diameter D50 obtained by a flow image analysis method in the range of 25 to 50 μm is supplied to the surface, and a toner image corresponding to the electrostatic latent image is formed on the surface. And an electrophotographic recording method including a step of transferring the toner image from the surface to a recording medium.

  According to the present invention, an electrophotographic recording technique capable of forming a high-quality image even when a toner having a large particle diameter is used is provided.

1 is a diagram schematically illustrating an electrophotographic recording apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a developing unit that can be used in the electrophotographic recording apparatus shown in FIG. 1. FIG. 3 is a plan view schematically showing an image formed on a sheet in the embodiment.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 schematically shows an electrophotographic recording apparatus according to an embodiment of the present invention.

  An electrophotographic recording apparatus 1 shown in FIG. 1 includes a housing 2 and a cassette 3, a transport device 4, a developing unit 5, an exposure device (not shown), a transfer device (not shown), and a fixing device 6 installed in the housing. Contains. Reference numeral 7 denotes a discharge tray provided at the top of the housing 2.

  The cassette 3 contains a recording medium P. The recording medium P is, for example, paper, cloth, or an article obtained from paper or cloth such as clothing.

  The transport device 4 sequentially transports the recording medium P stored in the cassette 3 to the developing unit 5, the fixing device 6, and the discharge tray 7. The conveying device 4 includes, for example, a driving roller, a driven roller, and a conveying belt that is stretched over them.

  The developing unit 5 forms a toner image on the recording medium P together with the exposure device and the transfer device.

  The developing unit 5 includes a photoconductor, a charging device (charging unit), and a developing device (developing unit). The exposure apparatus (exposure unit) includes an optical writing head provided with a laser light source or an LED (light-emitting diode) light source. The transfer device (transfer unit) is, for example, a transfer roller that faces the photoconductor with the conveyance belt interposed therebetween. Although FIG. 1 depicts a configuration in which a toner image is directly transferred from a photosensitive member to a recording medium P, the transfer device uses an intermediate transfer member that uses an intermediate transfer member such as an intermediate transfer belt or an intermediate transfer roller. A method may be adopted.

  The developing unit 5, the exposure device, and the transfer device form a toner image on the recording medium P by the method described below.

  First, the charging device uniformly charges the surface of the photoreceptor. Next, the exposure apparatus exposes the surface of the photoconductor according to the image information. This reduces the amount of charge in the exposed area of the photoreceptor and creates a potential difference between the exposed and unexposed areas. That is, an electrostatic latent image is formed.

  Next, the developing device supplies charged toner to the surface of the photoreceptor. At this time, using the potential difference between the exposed area and the unexposed area, the toner is attached only to one of the exposed area and the unexposed area. As described above, a toner image is formed on the surface of the photoreceptor.

  Next, the transfer device transfers the toner image formed thereon from the photoconductor onto the recording medium P conveyed by the conveying device 4 using electrostatic force. As described above, a toner image is formed on the recording medium P.

  The fixing device 6 fixes at least one of heat and pressure to the toner image on the recording medium P to fix the toner image on the recording medium P. The fixing device 6 includes, for example, a heater and rolls on the surface of the recording medium P on which the toner image is provided, and rolls on the back surface of the recording medium P, thereby fixing the recording medium P to the fixing roller. And a pressure roller that pressurizes toward the surface.

FIG. 2 is a cross-sectional view schematically showing an example of a developing unit that can be used in the electrophotographic recording apparatus shown in FIG.
The developing unit 5 shown in FIG. 2 includes a developing device 52. The developing device 52 includes a toner cartridge 55 and a developing unit 57 having an exterior frame 56.

  The toner cartridge 55 includes an upper toner hopper 53, a lower toner hopper 54, an agitator 529, a waste toner storage pipe 528, and a waste toner collection bag 527. The toner cartridge 55 is attached to the exterior frame 56 via a seal member 530.

  The toner cartridge 55 contains toner, for example, nonmagnetic one-component toner containing an external additive. This toner has a volume-based median diameter D50 obtained by a flow image analysis method in the range of 25 to 50 μm, and a glass transition point in the range of −30 ° C. to 30 ° C.

  The agitator 529 is installed at the center of the toner hopper 54 and agitates the toner in the toner cartridge 55. The toner cartridge 55 operates the agitator 529 to supply toner to the developing unit 57 from an opening provided in a lower portion thereof.

  The waste toner storage pipe 528 and the waste toner collection bag 527 are installed in the toner hopper 53. The toner cartridge 55 stores waste toner supplied by a cleaner 522 described later in a waste toner storage pipe 528 and a waste toner collection bag 527.

  The developing unit 57 includes a stirring member 511, a supply roller 59, a developing roller 58, and a doctor blade 510.

  The agitating member 511 is installed in a region between the toner cartridge 55 and the supply roller 59. The agitating member 511 agitates the toner supplied from the toner cartridge 55 to the developing unit 57.

  The supply roller 59 includes, for example, a cored bar and conductive foamed urethane. A DC power source 532 that supplies a negative-polarity supply bias, for example, a supply bias of −800 V, is connected to the core of the supply roller 59. The supply roller 59 contacts the developing roller 58 and rotates in the same direction as the developing roller 58 (counterclockwise in FIG. 2) to supply toner to the developing roller 58.

  The developing roller 58 includes a metal core and a conductive elastic layer provided thereon, for example, a urethane rubber layer imparted with conductivity. The core of the developing roller 58 is connected to a DC power source 531 that supplies a negative polarity developing bias, for example, a developing bias of −800V. The developing roller 58 rotates in the same direction as the supply roller 59 (counterclockwise in FIG. 2), and supplies toner to the surface of the photosensitive drum 521, which will be described later, using electrostatic force.

  The doctor blade 510 is made of an elastic metal plate, for example. The doctor blade 510 has one end fixed by a holding member and the other end pressed against the developing roller 58. The doctor blade 510 is connected to a DC power source 533 that supplies a negative polarity doctor bias, for example, a doctor bias of −800V. The doctor blade 510 makes the thickness of the toner layer on the developing roller 58 uniform.

  A drum unit 524 including a photosensitive drum 521, a charging roller 523, and a cleaner 522 is further incorporated in the exterior frame 56. The drum unit 524 constitutes a developing drum unit together with the developing unit 57 of the developing device 52.

  The photoconductor drum 521 is an example of a photoconductor. The photoconductor drum 521 is an organic photoconductor formed by uniformly depositing an organic photoconductor on the surface of a conductive metal roller, for example. The metal roller of the photosensitive drum 521 is grounded.

The charging start voltage V _th of the photosensitive drum 521 is, for example, −650V. The charging start voltage _Vth is the voltage applied when the surface of the photosensitive drum 521 starts charging when a DC voltage is applied to the charging roller 523 and the absolute value thereof is increased.

  The charging roller 523 is an example of a charging device. The charging roller 523 uniformly charges the surface of the photosensitive drum 521 by a contact charging method. According to an example, the charging roller 523 charges the surface of the photosensitive drum 521 to a negative polarity potential.

  The charging roller 523 includes, for example, a cored bar and an elastic body layer provided thereon. The elastic body layer is, for example, conductive or semiconductive. A power source (not shown) is connected to the core of the charging roller 523. This power supply supplies a pulsating voltage to the charging roller 523.

  Here, the pulsating voltage is a voltage obtained by superimposing an alternating voltage such as an oscillating voltage on a direct current voltage, and oscillating within one of the negative polarity and positive polarity ranges. Here, as an example, the pulsating voltage is assumed to be a voltage that oscillates within a negative polarity range.

The peak _-to- peak voltage V _p−p of the pulsating current voltage, that is, the difference between the maximum value and the minimum value of the pulsating current voltage is in a range of 1.7 to 2.0 times the absolute value of the charging start voltage V _th described above. Preferably, it is within the range of 1.7 to 1.9 times the absolute value of the charging start voltage _Vth . When the ratio of the difference between the maximum value and the minimum value of the pulsating voltage with respect to the absolute value of the charging start voltage _Vth is too small, the amount of toner on the surface of the photosensitive drum 521 is small and image blurring is likely to occur. If this ratio is too large, uneven charging occurs on the surface of the photosensitive drum 521, and therefore, an area where the amount of toner is excessive is generated on the surface of the photosensitive drum 521. As a result, an image on the recording medium P is generated. It is easy to generate defects such as black spots.

The cleaner 522 includes a cleaning blade 526 and a conveying screw 525.
The cleaning blade 526 is in contact with the peripheral surface of the photosensitive drum 521. The cleaning blade 526 removes waste toner remaining on the peripheral surface from the photosensitive drum 521 after the transfer of the toner image from the photosensitive drum 521 to the recording medium P. The transfer roller is connected to a DC power supply for supplying a positive transfer bias, for example, a +1000 V transfer bias.

  The conveying screw 525 removes the waste toner removed by the cleaning blade 526 from the conveying screw 525 b installed in the upper left outer frame 56 a of the outer frame 56 and the waste toner storage pipe provided in the upper toner hopper 53. The toner is sent to a waste toner collecting bag 527 through a conveying screw 525c in 528.

  As described above, when a toner having a large particle diameter is used and charging is performed by a contact charging method using a pulsating voltage, the image may be blurred. This image blur is caused by the disturbance of the toner image in the powder state on the photoconductor, and this disturbance of the toner image is considered to be caused by the contamination of the surface of the photoconductor.

  One of the causes of this contamination is a discharge product generated when a discharge is generated between the charging roller and the photoconductor to charge the photoconductor. When this discharge product adheres to the photoconductor and accumulates, the image formation on the photoconductor surface by the developing roller is hindered, resulting in image blur.

  Another cause of contamination is adhesion of free toner or external additives on the photoreceptor. In other words, the AC component of the pulsating voltage supplied to the charging roller may promote adhesion of free toner and external additives on the photosensitive member when the photosensitive member is charged. When such free substance adheres, the sensitivity of the surface of the photoreceptor is different between the part where the adherence has occurred and the other part. This difference in sensitivity hinders image formation on the surface of the photoreceptor by the developing roller, resulting in image blur.

  The generation of discharge products and the attachment of free substances are, for example, a high voltage of about 1600 to 2000V between the peaks of the pulsating voltage supplied to the charging roller in order to set the surface potential of the photoreceptor to about -800V. This is particularly noticeable.

  When a hard image forming toner having a particle size as small as about 10 μm is used, the toner has a large specific surface area and high hardness. Most of the liberated material is scraped off by the cleaning blade together with the toner remaining on the surface of the photosensitive member when the surface of the photosensitive member is cleaned by the cleaning blade. However, when a toner having a large particle diameter is used, the effect described above with respect to the image forming toner is very small because the toner has a small specific surface area. In particular, since the thermoplastic resin powder toner has not only a large particle size but also flexibility, when the toner is used, the effects described above for the image forming toner are hardly obtained.

  For this reason, when a toner having a large particle diameter, particularly a toner having a large particle diameter and flexibility, such as a thermoplastic resin powder toner, is used, discharge products and free particles on the surface of the photoreceptor are used. This causes accumulation of things. As a result, the charging uniformity on the surface of the photoreceptor becomes insufficient. In addition, a necessary amount of toner cannot be supplied onto the photoreceptor. That is, the loading amount becomes insufficient. Therefore, the contour of the image becomes ambiguous.

  Note that the generation of discharge products can be suppressed by shortening the energization time to the charging roller. However, in the actual printing process, there is a limit to shortening the energization time to the charging roller, and a sufficient effect cannot be obtained for a long time use.

  In addition, for example, a discharge product can be captured by zeolite by installing a duct in the machine. However, this method needs to install a duct in the vicinity of the place where the discharge product is generated, and it is difficult to adopt this method both in terms of space and cost.

  Another possible method is to add an abrasive material to the cleaning blade or toner and physically scrape off the deposits. However, it is difficult to physically scrape off the deposit without damaging the photoreceptor surface. In addition, it is difficult to design the positions of the members and to mix the toner. Further, since the polishing is performed, the life of the photosensitive member is shortened, and the powder generated by the polishing can cause a change in the color of the image.

In the electrophotographic recording apparatus 1 described with reference to FIGS. 1 and 2, the magnitude of the peak _-to- peak voltage Vpp of the pulsating voltage supplied to the charging roller is as described above. Despite the use of toner having a large particle size, a high-quality image can be formed. According to the electrophotographic recording apparatus 1, a high-quality image can be formed even if a flexible toner having a large particle size is used.

Example 1
94 parts by mass of Byron “GM990” (manufactured by Toyobo Co., Ltd.) which is a crystalline polyester resin, 3.0 parts by mass of “KTL500F” (manufactured by Kitamura Co., Ltd.) which is fluorine fine particles for charge control, 3.0 parts by mass of “FNP-0090” (manufactured by Nippon Seiwa Co., Ltd.), which is a wax for mold release, is mixed with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), and this mixture is continuously biaxially kneaded. It was melt kneaded with a machine. The obtained melt was freeze pulverized, and the pulverized product was classified using a sieve having an opening of 45 μm to obtain powder passing through the sieve as a base material.

  When the particle size of the matrix was measured with FPIA-2100 manufactured by Sysmex, the volume-based median diameter D50 was about 35 μm. Moreover, when the glass transition point and melting | fusing point of this base | substrate were measured by DSC6220 by Seiko Instruments Inc., glass transition point Tg was -5 degreeC and melting | fusing point was 108 degreeC.

  Next, 98 parts by mass of the base and 2 parts by mass of silica “R972” (manufactured by Nippon Aerosil Co., Ltd.) as an external additive were mixed in a Henschel mixer to obtain a thermoplastic resin powder toner.

Subsequently, N6000 (manufactured by Casio Computer Co., Ltd.) was modified to prepare an electrophotographic recording apparatus whose structure is schematically shown in FIG. In this electrophotographic recording apparatus, an organic photoreceptor having a charging start voltage V _p-p of −650 V was used.

  Next, a toner cartridge filled with the above thermoplastic resin powder toner was attached to the electrophotographic recording apparatus. Subsequently, under an environment where the temperature was 28 ° C. and the relative humidity was 80%, a total of 2,000 sheets of the image PP shown in FIG. Here, a pulsating voltage obtained by superimposing a DC voltage (charging DC) of −950 V and an AC voltage (charging AC) having a peak-to-peak voltage of 1200 V was applied to the charging roller. Further, here, the supply bias (supply DC) is set to −800 V, the development bias (development DC) is set to −800 V, the doctor bias (Doctor DC) is set to −800 V, the transfer bias (transfer DC) is set to +1000 V, and the process speed is set. Was 55 mm / s.

Then, the presence / absence of image blur, the amount of toner applied on the belt, and other problems at the time of printing the 2000th sheet were confirmed. Image blur was confirmed by the following criteria.
・ No image blur: ◎
・ Blurred images but no signs:
-Cannot distinguish alphabets and numbers: ×
The results are summarized in Table 1 below.

(Example 2)
The same test as in Example 1 was performed except that the peak _- to _- peak voltage V _p-p was 1300 V. The evaluation results are summarized in Table 1 below.

(Example 3)
The same test as in Example 1 was performed except that the peak _- to _- peak voltage V _p-p was set to 1100V. The evaluation results are summarized in Table 1 below.

Example 4
A base material having a volume-based median diameter D50 of about 50 μm was obtained in the same manner as in Example 1 except that the sieve to be used was changed. Next, a thermoplastic resin powder toner was obtained by the same method as in Example 1 except that this base was used. Thereafter, the same test as in Example 1 was performed except that this thermoplastic resin powder toner was used. The evaluation results are summarized in Table 1 below.

(Example 5)
The same test as in Example 4 was performed, except that the peak _- to _- peak voltage V _p-p was 1300 V. The evaluation results are summarized in Table 1 below.

(Example 6)
The same test as in Example 4 was performed except that the peak _- to _- peak voltage V _p-p was set to 1100V. The evaluation results are summarized in Table 1 below.

(Example 7)
A base material having a volume-based median diameter D50 of about 25 μm was obtained in the same manner as in Example 1 except that the sieve to be used was changed. Next, a thermoplastic resin powder toner was obtained by the same method as in Example 1 except that this base was used. Thereafter, the same test as in Example 1 was performed except that this thermoplastic resin powder toner was used. The evaluation results are summarized in Table 1 below.

(Example 8)
The same test as in Example 7 was performed except that the peak _- to _- peak voltage V _p-p was 1300 V. The evaluation results are summarized in Table 1 below.

Example 9
The same test as in Example 7 was performed except that the peak _- to _- peak voltage V _p-p was set to 1100V. The evaluation results are summarized in Table 1 below.

(Comparative Example 1)
The same test as in Example 1 was performed except that the peak _- to _- peak voltage V _p-p was set to 1400V. The evaluation results are summarized in Table 2 below.

(Comparative Example 2)
The same test as in Example 1 was performed except that the peak _- to _- peak voltage V _p-p was set to 1000V. The evaluation results are summarized in Table 2 below.

(Comparative Example 3)
The same test as in Example 4 was performed, except that the peak _- to _- peak voltage V _p-p was 1400 V. The evaluation results are summarized in Table 2 below.

(Comparative Example 4)
The same test as in Example 4 was performed except that the peak _- to _- peak voltage V _p-p was set to 1000V. The evaluation results are summarized in Table 2 below.

(Comparative Example 5)
The same test as in Example 7 was performed except that the peak _- to _- peak voltage V _p-p was set to 1400V. The evaluation results are summarized in Table 2 below.

(Comparative Example 6)
The same test as in Example 7 was performed except that the peak _- to _- peak voltage V _p-p was set to 1000V. The evaluation results are summarized in Table 2 below.

As shown in Table 2, in Comparative Examples 1 to 6, image blurring, poor charging, or black spots occurred. The reason why image blur occurred in Comparative Examples 1, 3 and 5 is considered to be due to excessive charging AC superposition. Further, black spots were generated in Comparative Examples 2, 4 and 6 because the peak _-to- peak voltage V _p-p was small, charging unevenness occurred on the surface of the photosensitive drum, and the toner amount was excessive on the surface of the photosensitive drum. This is thought to be due to the region.

  On the other hand, in Examples 1 to 9, as shown in Table 1, none of image blur, charging failure, and black spots occurred, and a high-quality image could be formed.

  As mentioned above, although several embodiment of this invention was described, all of these are contained in the invention described in the claim, and its equal range.

The invention described in the claims is appended below.
[1]
A photoreceptor,
A pulsating voltage having a peak _-to- peak voltage V _{p-p in} the range of 1.7 to 2.0 times the absolute value of the charging start voltage _Vth of the photosensitive member while being in contact with the surface of the photosensitive member. A charging unit that is applied to the body to charge the surface;
An exposure unit that irradiates light to the charged surface to form an electrostatic latent image on the surface;
A toner having a volume-based median diameter D50 obtained by a flow image analysis method in the range of 25 to 50 μm is supplied to the surface on which the electrostatic latent image has been formed, so as to correspond to the electrostatic latent image. A developing unit for forming a toner image on the surface;
An electrophotographic recording apparatus comprising: a transfer unit that transfers the toner image from the surface to a recording medium.
[2]
The electrophotographic recording apparatus according to [1], wherein the charging unit applies a pulsating voltage in which the peak _-to- peak voltage _Vp-p is in a range of 1.7 to 1.9 times the absolute value.
[3]
A pulsating voltage having a peak-to-peak voltage V _{p-p in} the range of 1.7 to 2.0 times the absolute value of the charging start voltage V _th of the photosensitive member is applied to the photosensitive member by a contact method, and Charging the surface of the photoreceptor,
Irradiating the charged surface with light to form an electrostatic latent image on the surface;
A toner having a volume-based median diameter D50 obtained by a flow image analysis method in the range of 25 to 50 μm is supplied to the surface on which the electrostatic latent image has been formed, so as to correspond to the electrostatic latent image. Forming a toner image on the surface;
An electrophotographic recording method comprising: transferring the toner image from the surface to a recording medium.
[4]
The electrophotographic recording method according to [3], wherein the peak _- to _- peak voltage _Vp-p is within a range of 1.7 to 1.9 times the absolute value.

  DESCRIPTION OF SYMBOLS 1 ... Electrophotographic recording device, 2 ... Housing, 3 ... Cassette, 4 ... Conveying device, 5 ... Developing unit, 6 ... Fixing device, 7 ... Discharge tray, 52 ... Developing device, 53 ... Toner hopper, 54 ... Toner hopper 55 ... toner cartridge, 56 ... exterior frame, 56a ... upper left exterior frame, 57 ... developing unit, 58 ... developing roller, 59 ... supply roller, 510 ... doctor blade, 511 ... stirring member, 521 ... photoconductor drum, 522 ... Cleaner, 523 ... charge roller, 524 ... drum unit, 525 ... conveying screw, 525b ... conveying screw, 525c ... conveying screw, 526 ... cleaning blade, 527 ... waste toner collection bag, 528 ... waste toner containing pipe, 529 ... agitator, 530 ... Sealing member, 531 ... DC power supply, 532 ... DC power supply, 533 ... DC power supply , P ... recording medium, PP ... image.

Claims (4)

A photoreceptor,
A pulsating voltage having a peak _-to- peak voltage V _{p-p in} the range of 1.7 to 2.0 times the absolute value of the charging start voltage _Vth of the photosensitive member while being in contact with the surface of the photosensitive member. A charging unit that is applied to the body to charge the surface;
An exposure unit that irradiates light to the charged surface to form an electrostatic latent image on the surface;
A toner having a volume-based median diameter D50 obtained by a flow image analysis method in the range of 25 to 50 μm is supplied to the surface on which the electrostatic latent image has been formed, so as to correspond to the electrostatic latent image. A developing unit for forming a toner image on the surface;
An electrophotographic recording apparatus comprising: a transfer unit that transfers the toner image from the surface to a recording medium. 2. The electrophotographic recording apparatus according to claim 1, wherein the charging unit applies a pulsating voltage in which the peak _-to- peak voltage V _p−p is within a range of 1.7 to 1.9 times the absolute value. A pulsating voltage having a peak-to-peak voltage V _{p-p in} the range of 1.7 to 2.0 times the absolute value of the charging start voltage V _th of the photosensitive member is applied to the photosensitive member by a contact method, and Charging the surface of the photoreceptor,
Irradiating the charged surface with light to form an electrostatic latent image on the surface;
A toner having a volume-based median diameter D50 obtained by a flow image analysis method in the range of 25 to 50 μm is supplied to the surface on which the electrostatic latent image has been formed, so as to correspond to the electrostatic latent image. Forming a toner image on the surface;
An electrophotographic recording method comprising: transferring the toner image from the surface to a recording medium. 4. The electrophotographic recording method according to claim 3, wherein the peak _- to _- peak voltage _Vp-p is within a range of 1.7 to 1.9 times the absolute value.