Method and apparatus for an electrophotographic printer where voltage magnitude applied to charge roller and intensity of illumination unit vary depending on type of print job submitted

• US 6,806,895 B2
• Filed: 09/24/2001
• Issued: 10/19/2004
• Est. Priority Date: 01/26/2001
• Status: Expired due to Fees

• Current Assignee: S-Printing Solution Co., Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Jeong, Su-jong
• Primary Examiner(s): LEE, SUSAN SHUK YIN
• Application Number:
  US09/960,305
• Publication Number:
  US 20020101496A1
• Time in Patent Office: 1,121 Days
• Field of Search: 399/50, 399/39, 399/45, 399/88, 399/82, 399/37, 399/51, 347/140
• US Class Current: 347/140
• CPC Class Codes: G03G 15/0266 Arrangements for controlling the amount of charge
• CPC Class Codes: G03G 2215/021 by contact, friction or induction

Abstract

An electrophotographic printing method and apparatus in which a charge voltage is appropriately adjusted depending on the resolution selected for electrophotographic printing or the print mode are provided. The electrophotographic printing method and electrophotographic imaging apparatus provide for selecting a resolution for electrophotographic printing; charging an organic photoconductor (OPC) by applying to a charge roller an appropriate charge voltage depending on the selected resolution; forming an electrostatic latent image on the charged OPC by a laser scanning unit (LSU) and applying toner particles adhering to a developer roller to the electrostatic latent image to form a visible image; and transferring the visible image formed on the OPC to a sheet of print paper. By selecting the print resolution or print mode, the charge voltage can be adjusted depending on the print resolution or print mode, so that an image can be obtained with reduced image concentration variation.

Claims

1. An electrophotographic image printing method for an electrophotographic imaging apparatus, comprising the steps of:

providing an electrophotographic imaging apparatus, the electrophotographic imaging apparatus including;

a charge roller;

a developer roller;

a laser scanning unit;

a transfer roller;

an organic photoconductor;

a power supply unit for supplying power to the charge roller, the developer roller, the laser scanning unit, and the transfer roller; and

a controller for controlling the power supply unit, the charge roller, the developer roller, the laser scanning unit, the transfer roller, and the organic photoconductor;

selecting a resolution for electrophotographic printing;

charging the organic photoconductor by selectively applying, to the charge roller, a charge voltage corresponding to the resolution selected for the electrophotographic printing;

setting the charge voltage applied to the charge roller to be relatively higher in magnitude for a lower level of the resolution selected than for a higher level of the resolution selected;

forming an electrostatic latent image on the charged organic photoconductor by means of the laser scanning unit and applying toner particles adhering to the developer roller to the electrostatic latent image to form a visible image; and

transferring the visible image formed on the organic photoconductor to a print medium.

2. The method of claim 1, wherein the resolution selected is any one of 600 dpi. and 1200 dpi.

3. The method of claim 1, wherein a charge voltage of −

1.35 kV is applied to the charge roller as the charge voltage when the resolution selected is 1200 dpi., and a charge voltage of −

1.4 kV is applied to the charge roller as the charge voltage when the selected resolution is 600 dpi.

4. The method of claim 1, wherein the charge voltage is selectively applied to the charge roller to reduce a gray pattern level variation.

5. The method of claim 1, further comprising the step of:

selectively adjusting the charge voltage applied to the charge roller in correspondence to the resolution selected for the electrophotographic printing to reduce image concentration variation.

6. The method of claim 1, wherein, during the charging step, said controller and said power supply unit automatically apply a different magnitude of DC voltage to said charge roller based on said selected resolution immediately prior to and during the formation of said electrostatic image on said organic photoconductor.

7. The method of claim 6, said laser scanning unit automatically applying a different power during said forming step based on said magnitude of said voltage applied to said charge roller.

8. The apparatus of claim 6, said laser scanning unit automatically applying a different power during said forming of said latent image based on said magnitude of said voltage applied to said charge roller.

9. An electrophotographic printing method for an electrophotographic imaging apparatus, comprising the steps of:

providing an electrophotographic imaging apparatus, the electrophotographic imaging apparatus including;

a charge roller;

a developer roller;

a laser scanning unit;

a transfer roller;

an organic photoconductor;

a power supply unit for supplying power to the charge roller, the developer roller, the laser scanning unit, and the transfer roller; and

a controller for controlling the power supply unit, the charge roller, the developer roller, the laser scanning unit, the transfer roller, and the organic photoconductor;

selecting a resolution for electrophotographic printing;

charging the organic photoconductor by selectively applying, to the charge roller, a charge voltage corresponding to the resolution selected for the electrophotographic printing;

forming an electrostatic latent image on the charged organic photoconductor by means of the laser scanning unit and applying toner particles adhering to the developer roller to the electrostatic latent image to form a visible image; and

transferring the visible image formed on the organic photoconductor to a print medium;

wherein a gray pattern level variation at a low resolution is reduced by applying a charge voltage to the charge roller that is relatively large in magnitude relative to a charge voltage applied to the charge roller to reduce the gray pattern level variation at a high resolution.

10. An electrophotographic printing method for an electrophotographic imaging apparatus, comprising the steps of:

providing an electrophotographic imaging apparatus, the electrophotographic imaging apparatus including;

a charge roller;

a developer roller;

a laser scanning unit;

a transfer roller;

an organic photoconductor;

a power supply unit for supplying power to the charge roller, the developer roller, the laser scanning unit, and the transfer roller; and

a controller for controlling the power supply unit, the charge roller, the developer roller, the laser scanning unit, the transfer roller, and the organic photoconductor;

selecting a print mode for electrophotographic printing;

charging the organic photoconductor by selectively applying, to the charge roller, a charge voltage having a magnitude which is dependent upon the print mode selected for the electrophotographic printing;

forming an electrostatic latent image on the charged organic photoconductor by means of the laser scanning unit and applying toner particles adhering to the developer roller to the electrostatic latent image to form a visible image; and

transferring the visible image formed on the organic photoconductor to a print medium;

wherein a charge voltage of −

1.4 kV is applied to the charge roller as the charge voltage when the print mode selected is a text mode, and a charge voltage of −

1.35 kV is applied to the charge roller as the charge voltage when the print mode selected is a graphics mode.

11. The electrophotographic printing method of claim 10, the voltage magnitude applied to the charge roller having a relatively higher magnitude when a text mode is selected as the print mode than when a graphics mode is selected as the print mode.

12. The method of claim 10, the print mode selected corresponding to one of a text mode and a graphics mode.

13. The method of claim 12, the text mode being of a relatively lower resolution than a resolution for the graphics mode.

14. The method of claim 10, wherein it is a DC magnitude of voltage and not an AC magnitude of voltage applied to the charge roller that is varied and dependent upon the selected print mode.

15. The method of claim 10, further comprising the step of:

selectively adjusting the charge voltage applied to the charge roller in correspondence to the print mode selected for the electrophotographic printing to reduce image concentration variation.

16. The method of claim 10, wherein, during the charging step, said controller and said power supply unit automatically apply a different magnitude of voltage to said charge roller based on said selected print mode immediately prior to and during the formation of said electrostatic image on said organic photoconductor.

17. The method of claim 16, said laser scanning unit automatically applying a different power during said forming step based on said magnitude of said voltage applied to said charge roller.

18. An electrophotographic printing method for an electrophotographic imaging apparatus, comprising the steps of:

providing an electrophotographic imaging apparatus, the electrophotographic imaging apparatus including;

a charge roller;

a developer roller;

a laser scanning unit;

a transfer roller;

an organic photoconductor;

a power supply unit for supplying power to the charge roller, the developer roller, the laser scanning unit, and the transfer roller; and

a controller for controlling the power supply unit, the charge roller, the developer roller, the laser scanning unit, the transfer roller, and the organic photoconductor;

selecting a print mode for electrophotographic printing;

charging the organic photoconductor by selectively applying, to the charge roller, a charge voltage having a magnitude which is dependent upon the print mode selected for the electrophotographic printing;

forming an electrostatic latent image on the charged organic photoconductor by means of the laser scanning unit and applying toner particles adhering to the developer roller to the electrostatic latent image to form a visible image; and

transferring the visible image formed on the organic photoconductor to a print medium;

wherein a gray pattern level variation at a low resolution is reduced by applying a charge voltage to the charge roller that is relatively large in magnitude relative to a charge voltage applied to the charge roller to reduce the gray pattern level variation at a high resolution.

19. An electrophotographic imaging apparatus for electrophotographic printing, comprising:

a charge roller;

a developer roller;

a laser scanning unit;

a transfer roller;

an organic photoconductor;

a power supply unit for supplying power to the charge roller, the developer roller, the laser scanning unit, and the transfer roller;

a controller for controlling the power supply unit, the charge roller, the developer roller, the laser scanning unit, the transfer roller, and the organic photoconductor;

means for selecting a resolution for electrophotographic printing;

means for selectively applying, to the charge roller, a charge voltage so as to charge the organic photoconductor, the charge voltage corresponding to the resolution selected for the electrophotographic printing;

means for forming an electrostatic latent image on the charged organic photoconductor, and for applying toner particles adhering to the developer roller to the electrostatic latent image to form a visible image; and

means for transferring the visible image formed on the organic photoconductor to a print medium;

wherein the charge voltage selectively applied to the charge roller is relatively large in magnitude for a lower level of the selected resolution and is relatively small in magnitude for a higher level of the selected resolution.

20. The electrophotographic imaging apparatus of claim 19, wherein a charge voltage of −

1.35 kV is applied to the charge roller as the charge voltage when the resolution selected is 1200 dpi., and a charge voltage of −

1.4 kV is applied to the charge roller as the charge voltage when the resolution selected is 600 dpi.

21. The electrophotographic printing apparatus of claim 19, wherein one of −

1.4 kV and −

1.35 kV is selectively applied to the charge roller as the charge voltage.

22. The apparatus of claim 19, wherein said controller and power supply unit automatically apply a voltage of a different magnitude to said charge roller based on said selected resolution immediately prior to and during the formation of said electrostatic image on said organic photoconductor.

23. The apparatus of claim 22, said laser scanning unit automatically applying a different power during said forming of said latent image based on said magnitude of said voltage applied to said charge roller.

24. An electrophotographic imaging apparatus for electrophotographic printing, comprising:

a charge roller;

a developer roller;

a laser scanning unit;

a transfer roller;

an organic photoconductor, said organic photoconductor being charged by said charge roller;

an input unit for input of a print job, and for input of a print mode for said print job;

a power supply unit supplying power to the charge roller, the developer roller, the laser scanning unit, and the transfer roller; and

a controller connected to said input unit and said power supply unit, said controller being programmed and configured to control the power supply unit, the charge roller, the developer roller, the laser scanning unit, the transfer roller, and the organic photoconductor, said controller being programmed and configured to cause said power supply unit to apply one of a first voltage having a first magnitude and a second voltage having a second, different magnitude to said charge roller based on a selected print mode for said print job, said laser scanning unit illuminating said organic photoconductor to form an electrostatic latent image on the charged organic photoconductor, said developer roller applying toner particles to the electrostatic latent image on the organic photoconductor to form a visible image on the organic photoconductor, said transfer roller transferring the visible image formed on the organic photoconductor to a print medium;

wherein the power supply unit selectively charges the charge roller with a charge voltage that is relatively high in magnitude when said selected print mode is text mode and relatively low in magnitude when said selected print mode is graphics mode.

25. The electrophotographic imaging apparatus of claim 24, wherein the power supply unit applies, to the charge roller, a charge voltage of −

1.35 kV DC as the first voltage magnitude when the print mode selected is the graphics mode, and the power supply unit applies, to the charge roller, a charge voltage of −

1.4 kV DC as the second voltage magnitude when the print mode selected is the text mode.

26. The electrophotographic printing apparatus of claim 24, said controller being programmed and configured to cause said laser scanning unit to illuminate said organic photoconductor to form said latent image on said organic photoconductor at one of a first power and a second and different power based on the print mode selected.

27. A method for forming an image in an electrophotographic apparatus, said method comprising the steps of:

submitting a print job from a user via software, said print job comprising a type of print job selected by said user;

automatically charging a charge roller to a magnitude of voltage based on the type of print job selected by the user prior to printing;

charging an organic photoconductor drum via said charge roller;

forming a latent image on said photoconductor drum by illuminating said photoconductor drum via a light source, a power of said light source forming the latent image being based on the magnitude of voltage to which said charge roller is charged; and

creating a visible image from said latent image via a developer roller positioned adjacent to said photoconductor drum, said developer roller supplying toner particles to said photoconductor drum to convert said latent image on said photoconductor drum into said visible image; and

transferring the visible image to a print medium;

wherein, when the type of print job is a resolution of the print job, the magnitude of voltage to which said charge roller is charged is greater for a lower resolution and smaller for a higher resolution.

28. The method of claim 27, wherein said controller causes said light source to operate at an appropriate power level based on the magnitude of voltage applied to said charge roller.

29. An electrophotographic imaging apparatus for electrophotographic printing, comprising:

a charge roller;

a developer roller;

a laser scanning unit;

a transfer roller;

a photoconductive drum, said photoconductive drum being charged by said charge roller, said laser scanning unit illuminating said photoconductive drum to form a latent image on said photoconductive drum, and said charge roller, said developer roller, said transfer roller and said laser scanning unit being disposed in operational relationship to said photoconductive drum;

an input unit for inputting a print job and selecting a print mode for said print job;

a power supply unit for supplying power to the charge roller, the developer roller, the laser scanning unit, and the transfer roller; and

a controller connected between said input unit and said power supply, said controller being programmed and configured to control the power supply unit and cause said power supply to apply one of a first DC voltage magnitude and a second and different DC voltage magnitude to said charge roller based on said selected print mode for said print job, said laser scanning unit illuminating said photoconductive drum to form an electrostatic latent image on the charged photoconductive drum, said developer roller applying toner particles to the electrostatic latent image on the photoconductive drum to form a visible image on the photoconductive drum, said transfer roller transferring the visible image formed on the photoconductive drum to a print medium;

wherein the power supply unit selectively charges the charge roller with a charge voltage that is relatively high in DC magnitude when said selected print mode is text mode, and with a charge voltage which is relatively low when said print mode is graphics mode.

30. The electrophotographic imaging apparatus of claim 29, wherein the power supply unit applies, to the charge roller, a charge voltage of −

1.35 kV DC when the selected print mode is the graphics mode, and the power supply unit applies, to the charge roller, a charge voltage of −

1.4 kV DC when the selected print mode is the text mode.

31. A method for forming an image in an electrophotographic apparatus, said method comprising the steps of:

submitting a print job from a user via software, said print job comprising a type of print job selected by said user;

automatically charging a charge roller to a magnitude of voltage based on the type of print job selected by the user prior to printing;

charging an organic photoconductor drum via said charge roller;

forming a latent image on said photoconductor drum by illuminating said photoconductor drum via a light source, a power of said light source forming the latent image being based on the magnitude of voltage to which said charge roller is charged; and

creating a visible image from said latent image via a developer roller positioned adjacent to said photoconductor drum, said developer roller supplying toner particles to said photoconductor drum to convert said latent image on said photoconductor drum into said visible image; and

transferring the visible image to a print medium;

wherein, when the type of print job is a selection between a text mode and a graphics mode, the magnitude of voltage to which said charge roller is charged is greater for the text mode and smaller for the graphics mode.