Image forming apparatus controlled according to smallest non-zero toner density

Claim 1

An image forming apparatus comprising: a photoconductor; an image forming means for forming a toner image on the photoconductor; a control means for setting the value of a predetermined operating parameter of the image forming means in order to control the amount of adhered toners of the toner image formed by the image forming means; and a detection means for detecting the amount of the adhered toners; wherein the control means changes the value of the operating parameter stepwise when the image forming means forms a plurality of toner images and the detection means detects the amount of the adhered toners of each toner image formed with use of the operating parameter, and the control means determines the value of the operating parameter which is used to form the toner image of the smallest amount of the adhered toners in the amounts detected by the detection means and sets the determined operating parameter of the image forming means when a document image is formed by the image forming means.

Claim 14

A method for controlling the image density for an image forming apparatus wherein the image signals of the densities of an image to be formed are corrected with use of a gamma table in correspondence to the gamma characteristic of the image forming apparatus, a photoconductor is exposed with a laser beam at an intensity in accordance to the corrected image signals to form an electrostatic latent image, and the electrostatic latent image is developed with toners to form an toner image; the method comprising the steps of: sensitizing the photoconductor at a constant initial electric potential; exposing the photoconductor with the laser beam by changing the light intensity of the laser beam stepwise; developing the exposed photoconductor to form a toner image with toners; detecting the amounts of adhered toners of the toner images; determining the smallest light intensity for adhering toners on the photoconductor based on the detected values; and rewriting the gamma table according to the determined light intensity.

Claim 15

A method for controlling the image density for an image forming apparatus wherein the image signals of the densities of an image to be formed are corrected with use of a gamma table in correspondence to the gamma characteristic of the image forming apparatus, a photoconductor is exposed with a laser beam at an intensity in accordance to the corrected image signals to form an electrostatic latent image, and the electrostatic latent image is developed with toners to form an toner image; the method comprising the steps of: sensitizing the photoconductor at a constant initial electric potential; exposing the photoconductor with the laser beam by changing the light intensity of the laser beam stepwise; developing the exposed photoconductor to form a toner image with toners; detecting the amounts of adhered toners of the toner images; determining the smallest light intensity for adhering toners on the photoconductor based on the detected values; and rewriting the gamma table according to the determined light intensity.

Claim 16

A method for controlling the image density for an image forming apparatus wherein the image signals of the densities of an image to be formed are corrected with use of a gamma table in correspondence to the gamma characteristic of the image forming apparatus, a photoconductor is exposed with a laser beam at an intensity in accordance to the corrected image signals to form an electrostatic latent image, and the electrostatic latent image is developed with toners to form an toner image; the method comprising the steps of: sensitizing the photoconductor at a uniform initial electric potential; exposing the photoconductor with the laser beam by changing the light intensity of the laser beam stepwise by a first change quantity; developing the exposed photoconductor to form a toner image with toners; detecting the amount of adhered toners of the toner images; determining the first smallest light intensity which can adhere toners on the photoconductor based on the detected amounts of adhered toners; exposing the photoconductor with the laser beam by changing the light intensity of the laser beam stepwise at a second change quantity smaller than the first change quantity in an light intensity range determined from the first smallest light intensity; developing the exposed photoconductor to form toner images; detecting the amount of adhered toners of the toner images; determining the second smallest light intensity for adhering toners on the photoconductor based on the detected values; and changing the content of the gamma table according to the second smallest light intensity.

Claim 17

A method for controlling the image density for an image forming apparatus wherein the image signals of the densities of an image to be formed are corrected with use of a gamma table in correspondence to the gamma characteristic of the image forming apparatus, a photoconductor is exposed with a laser beam at an intensity in accordance to the corrected image signals to form an electrostatic latent image, and the electrostatic latent image is developed with toners to form an toner image; the method comprising the steps of: sensitizing the photoconductor at a uniform initial electric potential; exposing the photoconductor with the laser beam by changing the light intensity of the laser beam stepwise by a first change quantity; developing the exposed photoconductor to form a toner image with toners; detecting the amount of adhered toners of the toner images; determining the first smallest light intensity which can adhere toners on the photoconductor based on the detected amounts of adhered toners; exposing the photoconductor with the laser beam by changing the light intensity of the laser beam stepwise at a second change quantity smaller than the first change quantity in an light intensity range determined from the first smallest light intensity; developing the exposed photoconductor to form toner images; detecting the amount of adhered toners of the toner images; determining the second smallest light intensity for adhering toners on the photoconductor based on the detected values; and changing the content of the gamma table according to the second smallest light intensity.

Claim 18

A method for controlling the image density for an image forming apparatus including a photoconductor, a sensitizing means for sensitizing the photoconductor at a uniform initial electric potential, a correction means for correcting image signals of the densities of an image to be formed with use of a gamma table in correspondence to the gamma characteristic of the image forming apparatus, an exposure means for exposing the photoconductor at a light intensity in correspondence to the image signals corrected by the correction means to form an electrostatic latent image on the photoconductor, a development means for developing the electrostatic latent image with toners, and an application means for applying a predetermined bias electric potential to the development means; the method comprising the steps of: sensitizing the photoconductor at a predetermined standard initial electric potential by the sensitizing means; exposing the sensitized photoconductor with the laser beam at a predetermined light intensity of the laser beam; developing the exposed photoconductor to form a toner image by the development means to which a standard bias electric potential is applied; detecting the amount of toners adhered to the toner image; determining the initial electric potential and/or the bias electric potential based on the detected amount of toners; controlling the sensitizing means and/or the application means to set the initial electric potential and/or the bias electric potential as the determined values; exposing the photoconductor by the exposure means at light intensities changed stepwise; developing the photoconductor exposed at different light intensities with toners; detecting the amount of adhered toners of the toner images each in correspondence to the light intensity; determining the smallest light intensity for adhering toners on the photoconductor; and rewriting the content of the gamma table according to the determined smallest light intensity.

Claim 19

A method for controlling the image density for an image forming apparatus including a photoconductor, a sensitizing means for sensitizing the photoconductor at a uniform initial electric potential, a correction means for correcting image signals of the densities of an image to be formed with use of a gamma table in correspondence to the gamma characteristic of the image forming apparatus, an exposure means for exposing the photoconductor at a light intensity in correspondence to the image signals corrected by the correction means to form an electrostatic latent image on the photoconductor, a development means for developing the electrostatic latent image with toners, and an application means for applying a predetermined bias electric potential to the development means; the method comprising the steps of: sensitizing the photoconductor at a predetermined standard initial electric potential by the sensitizing means; exposing the sensitized photoconductor with the laser beam at a predetermined light intensity of the laser beam; developing the exposed photoconductor to form a toner image by the development means to which a standard bias electric potential is applied; detecting the amount of toners adhered to the toner image; determining the initial electric potential and/or the bias electric potential based on the detected amount of toners; controlling the sensitizing means and/or the application means to set the initial electric potential and/or the bias electric potential as the determined values; exposing the photoconductor by the exposure means at light intensities changed stepwise; developing the photoconductor exposed at different light intensities with toners; detecting the amount of adhered toners of the toner images each in correspondence to the light intensity; determining the smallest light intensity for adhering toners on the photoconductor; and rewriting the content of the gamma table according to the determined smallest light intensity.