Electrophotographic image forming apparatus comprising means for automatically adjusting image reproduction density

Claim 2

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential, thereby supplying an electric charge corresponding to said initial electric potential thereto; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; charger control means for controlling said charger means based on a detection result of said detection means so as to change said initial electric potential of said photoconductor; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the detection result of said detection means when said initial electric potential of said photoconductor is at an upper or lower limit value of a predetermined range; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, based on the gradation correction data selected by said selection means, according to an image density signal representing densities of respective pixels of an image to be formed.

Claim 3

The apparatus as claimed in claim 1, wherein said light projecting control means controls said light projecting means to change an area of a portion on said photoconductor projected corresponding to each pixel according to the image density signal.

Claim 4

The apparatus as claimed in claim 1, wherein said light projecting control means controls said light projecting means to change an intensity of the light projected onto said photoconductor according to the image density signal.

Claim 5

The apparatus as claimed in claim 1, wherein said detection means detects an image density of the toner image formed on said photoconductor.

Claim 6

The apparatus as claimed in claim 1, further comprising developing bias control means for controlling said voltage applying means to change the developing bias voltage based on the detection result of said detection means.

Claim 7

The apparatus as claimed in claim 1, wherein said charger means comprises an electrically charging electrode for supplying an electric charge to said photoconductor; and a grid electrode provided between said charging electrode and said photoconductor, said grid electrode regulating an amount of electric charge supplied from said charging electrode to said photoconductor, and said charger control means controls said charger means to change an electric potential of said grid electrode.

Claim 8

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; storage means for storing a plurality of gradation correction data; gradation control means for controlling said charger means to change an output thereof based on a detection result of said detection means, and for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means; correction means for correcting an image density signal representing densities of respective pixels of an image to be formed based on the gradation correction data selected by said gradation control means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means according to the image density signal corrected by said correction means; wherein said gradation control means changes the selected gradation correction data to another gradation correction data while making the output of said charger means constant based on the detection result of said detection means when the output of said charger means is a predetermined value.

Claim 9

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; storage means for storing a plurality of gradation correction data; gradation control means for controlling said charger means to change an output thereof based on a detection result of said detection means, and for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means; correction means for correcting an image density signal representing densities of respective pixels of an image to be formed based on the gradation correction data selected by said gradation control means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means according to the image density signal corrected by said correction means; wherein said gradation control means changes the selected gradation correction data to another gradation correction data while making the output of said charger means constant based on the detection result of said detection means when the output of said charger means is a predetermined value.

Claim 10

The apparatus as claimed in claim 7, further comprising toner image forming means for forming a reference toner image on said photoconductor, wherein said detection means detects an image density of the reference toner image formed by said toner image forming means.

Claim 11

The apparatus as claimed in claim 7, wherein said gradation control means controls said voltage applying means to change the developing bias voltage based on the detection result of said detection means, and changes the selected gradation correction data to another gradation correction data making the developing bias voltage constant based on the detection result of said detection means when the developing bias voltage is a predetermined value.

Claim 12

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential, thereby supplying an electric charge corresponding to said initial electric potential thereto; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; developing bias voltage control means for controlling said voltage applying means to change the developing bias voltage based on a detection result of said detection means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the detection result of said detection means when the developing bias voltage is at an upper or lower limit value of a predetermined range; and light projecting control means for controlling said light projecting means to change a light amount of the light projected from said light projecting means onto said photoconductor, based on the gradation correction data selected by said selection means, according to an image density signal representing densities of respective pixels of an image to be formed.

Claim 13

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential, thereby supplying an electric charge corresponding to said initial electric potential thereto; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; developing bias voltage control means for controlling said voltage applying means to change the developing bias voltage based on a detection result of said detection means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the detection result of said detection means when the developing bias voltage is at an upper or lower limit value of a predetermined range; and light projecting control means for controlling said light projecting means to change a light amount of the light projected from said light projecting means onto said photoconductor, based on the gradation correction data selected by said selection means, according to an image density signal representing densities of respective pixels of an image to be formed.

Claim 14

The apparatus as claimed in claim 10, wherein said light projecting control means controls said light projecting means to change an area of a portion on said photoconductor projected corresponding to each pixel according to the image density signal.

Claim 15

The apparatus as claimed in claim 10, wherein said light projecting control means controls said light projecting means to change an intensity of the light projected onto said photoconductor according to the image density signal.

Claim 16

The apparatus as claimed in claim 10, wherein said detection means detects an image density of the toner image formed on said photoconductor.

Claim 17

The apparatus as claimed in claim 10, further comprising charger control means for controlling said charger means to change the initial electric potential of said photoconductor based on the detection result of said detection means.

Claim 18

The apparatus as claimed in claim 14, wherein said charger means comprises an electrically charging electrode for supplying an electric charge to said photoconductor; and a grid electrode provided between said charging electrode and said photoconductor, said grid electrode regulating an amount of electric charge supplied from said charging electrode to said photoconductor, and said charger control means controls said charger means to change an electric potential of said grid electrode.

Claim 19

An electrophotographic image forming apparatus comprising: a photoconductor; light projecting means for projecting a light onto said photoconductor so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; storage means for storing a plurality of gradation correction data; gradation control means for controlling said voltage applying means to change the developing bias voltage based on a detection result of said detection means, and for selecting one of the plurality of gradation correction data based on the developing bias voltage; correction means for correcting an image density signal representing densities of respective pixels of an image to be formed, based on the gradation correction data selected by said gradation control means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means according to the image density signal corrected by said correction means; wherein said gradation control means changes the selected gradation correction data to another gradation correction data while making the developing bias voltage constant based on the detection result of said detection means when the developing bias voltage is a predetermined value.

Claim 20

An electrophotographic image forming apparatus comprising: a photoconductor; light projecting means for projecting a light onto said photoconductor so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; storage means for storing a plurality of gradation correction data; gradation control means for controlling said voltage applying means to change the developing bias voltage based on a detection result of said detection means, and for selecting one of the plurality of gradation correction data based on the developing bias voltage; correction means for correcting an image density signal representing densities of respective pixels of an image to be formed, based on the gradation correction data selected by said gradation control means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means according to the image density signal corrected by said correction means; wherein said gradation control means changes the selected gradation correction data to another gradation correction data while making the developing bias voltage constant based on the detection result of said detection means when the developing bias voltage is a predetermined value.

Claim 21

The apparatus as claimed in claim 16, further comprising toner image forming means for forming a reference toner image on said photoconductor, wherein said detection means detects an image density of the reference toner image formed by said toner image forming means.

Claim 30

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; gradation control means for controlling said charger means and said voltage applying means to respectively change the output of said charger means and the developing bias voltage in predetermined ranges based on a detection result of said detection means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of an image to be formed, based on the gradation correction data selected by said selection means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means; wherein said selection means selects one of the plurality of gradation correction data stored by said storage means based on a detection result of said detection means when the output of said charger means and the developing bias voltage are respectively set to upper or lower limit values of predetermined ranges thereof.

Claim 31

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting a state of said photoconductor; gradation control means for controlling said charger means and said voltage applying means to respectively change the output of said charger means and the developing bias voltage in predetermined ranges based on a detection result of said detection means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of an image to be formed, based on the gradation correction data selected by said selection means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means; wherein said selection means selects one of the plurality of gradation correction data stored by said storage means based on a detection result of said detection means when the output of said charger means and the developing bias voltage are respectively set to upper or lower limit values of predetermined ranges thereof.

Claim 32

The apparatus as claimed in claim 22, wherein said light projecting control means controls said light projecting means to change an area of a portion on said photoconductor projected corresponding to each pixel according to the image density signal.

Claim 33

The apparatus as claimed in claim 22, wherein said light projecting control means controls said light projecting means to change an intensity of the light projected onto said photoconductor according to the image density signal.

Claim 34

The apparatus as claimed in claim 22, wherein said detection means detects an image density of the toner image formed on said photoconductor.

Claim 35

The apparatus as claimed in claim 22, further comprising further storage means for storing a plurality of combinations of the output of said charger means and the developing bias voltage, wherein said gradation control means selects one of the plurality of combinations stored by said further storage means based on the detection result of said detection means.

Claim 36

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; gradation control means for controlling said charger means and said voltage applying means to respectively change the output of said charger means and the developing bias voltage in predetermined ranges; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of an image to be formed, based on the gradation correction data selected by said selection means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means; wherein said selection means changes the selected gradation correction data to another gradation correction data while making the output of said charger and the developing bias voltage constant, when either one of the output of said charger means and the developing bias voltage is set to an upper or lower limit value of a predetermined range thereof.

Claim 37

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; gradation control means for controlling said charger means and said voltage applying means to respectively change the output of said charger means and the developing bias voltage in predetermined ranges; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of an image to be formed, based on the gradation correction data selected by said selection means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means; wherein said selection means changes the selected gradation correction data to another gradation correction data while making the output of said charger and the developing bias voltage constant, when either one of the output of said charger means and the developing bias voltage is set to an upper or lower limit value of a predetermined range thereof.

Claim 38

The apparatus as claimed in claim 27, further comprising operation means manually operable by an operator for adjusting an image density of a low density portion of the image to be formed, wherein said gradation control means controls said charger means to change the output of said charger means making the developing bias voltage constant, based on an operation result of said operation means.

Claim 39

The apparatus as claimed in claim 28, further comprising: toner image forming means for forming a reference toner image on said photoconductor; and detection means for detecting an image density of the reference toner image formed by said toner image forming means, wherein said gradation control means changes a combination of the output of said charger means and the developing bias voltage based on the image density detected by said detection means.

Claim 40

The apparatus as claimed in claim 27, further comprising operation means manually operable by an operator for adjusting an image density of a low density portion of the image to be formed, wherein said gradation control means changes a combination of the output of said charger means and the developing bias voltage based on an operation result of said operation means.

Claim 41

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; operation means manually operable by an operator for adjusting an image density of an image to be formed; charger control means for controlling said charger means to change the output of said charger means so as to change said initial electric potential of said photoconductor; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on an operation result of said operation means when the output of said charger means is set to an upper or lower limit value of a predetermined adjustable range thereof; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, based on the gradation correction data selected by said selection means, according to an image density signal representing image densities of respective pixels of the image to be formed.

Claim 42

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; operation means manually operable by an operator for adjusting an image density of an image to be formed; charger control means for controlling said charger means to change the output of said charger means so as to change said initial electric potential of said photoconductor; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on an operation result of said operation means when the output of said charger means is set to an upper or lower limit value of a predetermined adjustable range thereof; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, based on the gradation correction data selected by said selection means, according to an image density signal representing image densities of respective pixels of the image to be formed.

Claim 43

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; input means for inputting a fog removal level representing an image density of a low density portion of an image to be formed; gradation control means for controlling said charger means and said voltage applying means to change the output of said charger means while making the developing bias voltage constant based on the fog removal level inputted by said input means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of the image to be formed, based on the gradation correction data selected by said selection means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means, wherein said selection means selects one of the plurality of gradation correction data stored by said storage means based on the fog removal level inputted by said input means, when the output of said charger means is set to an upper or lower limit value of a predetermined adjustable range thereof.

Claim 44

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; input means for inputting a fog removal level representing an image density of a low density portion of an image to be formed; gradation control means for controlling said charger means and said voltage applying means to change the output of said charger means while making the developing bias voltage constant based on the fog removal level inputted by said input means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of the image to be formed, based on the gradation correction data selected by said selection means; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means, wherein said selection means selects one of the plurality of gradation correction data stored by said storage means based on the fog removal level inputted by said input means, when the output of said charger means is set to an upper or lower limit value of a predetermined adjustable range thereof.

Claim 45

The apparatus as claimed in claim 32, wherein said charger means comprises an electrically charging electrode for supplying an electric charge to said photoconductor; and a grid electrode provided between said charging electrode and said photoconductor, said grid electrode regulating an amount of electric charge supplied from said charging electrode to said photoconductor, and said gradation control means controls said charger means to change an electric potential of said grid electrode based on the fog removal level inputted by said input means.

Claim 46

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting an image density of the toner image formed on said photoconductive drum; first control means for controlling said charger means and said voltage applying means to change the output of said charger means and the developing bias voltage based on the image density detected by said detection means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of the image to be formed, based on the gradation correction data selected by said selection means; light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means; input means for inputting a fog removal level representing an image density of a low density portion of the image to be formed; and second control means for controlling said charger means and said voltage applying means to change the output of said charger means while making the developing bias voltage constant based on the fog removal level inputted by said input means; wherein said selection means selects one of the plurality of gradation correction data stored by said storage means based on the fog removal level inputted by said input means, when the output of said charger means is set to an upper or lower limit value of a predetermined adjustable range thereof.

Claim 47

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; developing means for developing the electrostatic latent image formed on said photoconductor with toner so as to form a toner image on said photoconductor; voltage applying means for applying a developing bias voltage to said developing means; detection means for detecting an image density of the toner image formed on said photoconductive drum; first control means for controlling said charger means and said voltage applying means to change the output of said charger means and the developing bias voltage based on the image density detected by said detection means; storage means for storing a plurality of gradation correction data; selection means for selecting one of the plurality of gradation correction data stored by said storage means based on the output of said charger means and the developing bias voltage; correction means for correcting an image density signal representing image densities of respective pixels of the image to be formed, based on the gradation correction data selected by said selection means; light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to the image density signal corrected by said correction means; input means for inputting a fog removal level representing an image density of a low density portion of the image to be formed; and second control means for controlling said charger means and said voltage applying means to change the output of said charger means while making the developing bias voltage constant based on the fog removal level inputted by said input means; wherein said selection means selects one of the plurality of gradation correction data stored by said storage means based on the fog removal level inputted by said input means, when the output of said charger means is set to an upper or lower limit value of a predetermined adjustable range thereof.

Claim 48

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to an image density signal representing image densities of respective pixels of the image to be formed, based on gradation correction data representing a relationship between the light amount of the light projected from said light projecting means onto said photoconductor and the image density signal, said gradation correction data being set so that a value of a ratio of the light amount of the projected light to the image density signal gradually increases from that of a predetermined reproduction start light amount as the projected light amount is changed from the reproduction start light amount to zero, said predetermined reproduction start light amount being the lowest projected light amount by which an image first starts to be reproduced.

Claim 49

An electrophotographic image forming apparatus comprising: a photoconductor; charger means for electrically charging said photoconductor to a predetermined initial electric potential; light projecting means for projecting a light onto said photoconductor electrically charged to said initial electric potential so as to form an electrostatic latent image on said photoconductor; and light projecting control means for controlling said light projecting means to change a light amount of the light projected onto said photoconductor by said light projecting means, according to an image density signal representing image densities of respective pixels of the image to be formed, based on gradation correction data representing a relationship between the light amount of the light projected from said light projecting means onto said photoconductor and the image density signal, said gradation correction data being set so that a value of a ratio of the light amount of the projected light to the image density signal gradually increases from that of a predetermined reproduction start light amount as the projected light amount is changed from the reproduction start light amount to zero, said predetermined reproduction start light amount being the lowest projected light amount by which an image first starts to be reproduced.