Provided is an electrophotographic photosensitive member including a support, an undercoat layer, a charge-generating layer, and a charge-transporting layer in the stated order, wherein with regard to an S.sub.0, an S.sub.1, an S.sub.2, an S.sub.3, and an S.sub.4 determined by a specific procedure (A), a ratio S.sub.1/S.sub.0 is 0.34 or less, and one of the S.sub.2, the S.sub.3, or the S.sub.4 is a positive value, and the other two thereof are negative values, or two thereof are positive values, and the other one thereof is a negative value.

A polyarylate resin includes repeating units represented by formulas (1), (2), (3), and (4).

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A third percentage is greater than 0% and less than 50%. The third percentage is a percentage of the number of repeats of the repeating unit represented by formula (3) relative to the total of the number of repeats of the repeating unit represented by formula (1) and the number of repeats of the repeating unit represented by formula (3). A fourth percentage is at least 35% and less than 70%. The fourth percentage is a percentage of the number of repeats of the repeating unit represented by formula (4) relative to the total of the number of repeats of the repeating unit represented by formula (2) and the number of repeats of the repeating unit represented by formula (4).

An electrophotographic photoreceptor includes a conductive substrate, and a lamination type photosensitive layer disposed on the conductive substrate and including a charge generation layer and a charge transport layer, in which the charge transport layer contains a polyester resin (1) having a dicarboxylic acid unit (A) represented by Formula (A) and a diol unit (B) represented by Formula (B), and a charge transport material, and in a case where a weight-average molecular weight Mw of the polyester resin (1) contained in the charge transport layer is defined as A (10,000), a value of a ratio M1/M2 of a mass M1 of the charge transport material contained in the charge transport layer to a mass M2 of the charge transport layer is defined as Cs, and an average thickness of the charge transport layer is defined as Ds (μm), expressions of 5≤A≤40, 0.28≤Cs≤0.55, 27≤Ds≤50, and 2.5≤(A×Ds)/(Cs×100)≤70.0 are satisfied.

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In Formula (A), n.sup.1 represents 1, 2, or 3, n.sup.1 number of m.sup.1's each independently represent 0, 1, 2, 3, or 4, m.sup.1 number of Ra.sup.1's each independently represent an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.

In Formula (B), Rb.sup.1 and Rb.sup.2 each independently represent a hydrogen atom, an alkyl group having 1 or more and 20 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an aralkyl group having 7 or more and 20 or less carbon atoms, Rb.sup.3, Rb.sup.4, Rb.sup.5, Rb.sup.6, Rb.sup.7, Rb.sup.8, Rb.sup.9, and Rb.sup.10 each independently represent a hydrogen atom, an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, an aralkyl group having 7 or more and 20 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, and Rb.sup.1 and Rb.sup.2 may be bonded to each other to form a cyclic alkyl group.

An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer includes a charge generating layer and a charge transport layer. The charge generating layer contains a phthalocyanine pigment and a first resin. A ratio of the mass of the phthalocyanine pigment to the mass of the first resin is greater than 2.0 and less than 3.5. A ratio A.sub.830/A.sub.783 of a second absorbance A.sub.830 to a first absorbance A.sub.783 of the charge generating layer is at least 0.97 and no greater than 1.10. The first absorbance A.sub.783 is an absorbance of the charge generating layer with respect to first light with a wavelength of 783 nm. The second absorbance A.sub.830 is an absorbance of the charge generating layer with respect to second light with a wavelength of 830 nm.

There is provided an electrophotographic photoreceptor including: a conductive support; and a photosensitive layer and a protective layer containing a cured product obtained by curing a curable compound, which are sequentially disposed on the conductive support. An area ratio A/B is 0.0045 or less, where A is an absorbance area at a wavelength of 1647 cm.sup.−1 to 1627 cm.sup.−1 and B is an absorbance area of a peak at a wavelength of 1800 cm.sup.−1 to 1647 cm.sup.−1 in an infrared absorption spectrum measurement of the protective layer. The photosensitive layer contains at least a hole transport material (HTM) and a radical acceptor compound. The electrophotographic photoreceptor is an electrophotographic photoreceptor including a protective layer with a high curing degree and having good initial electrical characteristics, excellent strong exposure characteristics, and excellent transfer repeatability.

An image forming apparatus includes an image bearing member, a charger, a light exposure device, a development device, a transfer belt, a primary transfer device, a secondary transfer device, and a cleaning member. The cleaning member is pressed against a circumferential surface of the image bearing member and collects residual toner remaining on the circumferential surface of the image bearing member as a result of primary transfer of a toner. The transfer belt has a surface resistivity of at least 6 Log Ω and no greater than 11 Log Ω. A linear pressure of the cleaning member on the circumferential surface of the image bearing member is at least 10 N/m and no greater than 40 N/m. The image bearing member includes a conductive substrate and a photosensitive layer of a single layer. The image bearing member satisfies formula (1): $\begin{array}{cc}0.06\leqq \frac{V}{\left(Q/S\right)\times \left(d/{\epsilon }_r.Math.{\epsilon }_0\right)}.& \left(1\right)\end{array}$

The present invention relates to an electrophotographic photoreceptor having a plurality of layers containing at least one outermost layer, wherein at least one of the outermost layer contains a polymer having a first structure where at least one carbonyl group is bonded to an aromatic group and a second structure represented by Formula (A). In Formula (A), at least two of R.sup.11 to R.sup.13 are groups represented by Formula (2), and in Formula (2), R.sup.21 represents a hydrogen atom or a methyl group, and R.sup.22 and R.sup.23 each independently represent a hydrogen atom, a hydrocarbon group or an alkoxy group:

##STR00001##

An image forming apparatus includes an image bearing member, a charger, a light exposure device, a development device, a transfer belt, a primary transfer device, a secondary transfer device, and a cleaning member. The cleaning member is pressed against a circumferential surface of the image bearing member and collects residual toner remaining on the circumferential surface of the image bearing member as a result of primary transfer of a toner. The transfer belt has a surface resistivity of at least 6 Log Ω and no greater than 11 Log Ω. A linear pressure of the cleaning member on the circumferential surface of the image bearing member is at least 10 N/m and no greater than 40 N/m. The image bearing member includes a conductive substrate and a photosensitive layer of a single layer. The image bearing member satisfies formula (1):

[00001]$\begin{array}{cc}0.60\leqq \frac{V}{\left(Q/S\right)\times \left(d/{\mathrm{.Math.}}_r.Math.{\mathrm{.Math.}}_0\right)}& \left(1\right)\end{array}$

The undercoat layer contains metal particles and a polyamide resin. The metal particle has a core and a coat layer covering at least a part of the core. The core contains titanium oxide. The coat layer contains at least a metal oxide different from titanium oxide. The metal oxide different from the titanium oxide is located on the outermost surface of the metal particles. The polyamide resin has an amide bond and an alkylene group. The absorption rate of the first peak derived from the amide bond to the second peak derived from the alkylene group to the first absorbance measured by infrared spectroscopy is ≥0.70.

An electrophotographic device equipped with a negatively-charged laminated electrophotographic photoreceptor that can be charged by a scorotron charging method, and includes a conductive substrate, and a charge generation layer and a charge transport layer sequentially provided on the conductive substrate, wherein the charge generation layer contains a charge generation material and a resin binder that is a poly(vinyl butyral) resin binder, and the charge transport layer contains a charge transport material that is either or both of stilbene compounds represented by Formula (1) and Formula (2), a binder resin, and an oxidation inhibitor that is tribenzylamine represented by Formula 3, wherein the conductive substrate is cylindrical, the electrophotographic photoreceptor has a difference between a maximum value and a minimum value of a surface potential in a circumferential direction, after exposure to ozone at an exposure dose of 100 ppm.Math.h, that is 12 V or less.