Method, control circuit, computer program product and printing device for an electrophotographic process with temperature-compensated discharge depth regulation

• US 7,027,078 B2
• Filed: 10/31/2003
• Issued: 04/11/2006
• Est. Priority Date: 10/31/2002
• Status: Active Grant

• Current Assignee: Oce Printing Systems GmbH (Canon Inc.)
• Original Assignee: Oce Printing Systems GmbH (Canon Inc.)
• Inventors: Reihl, Heiner
• Primary Examiner(s): PHAM, HAI CHI
• Application Number:
  US10/698,325
• Publication Number:
  US 20050063719A1
• Time in Patent Office: 893 Days
• Field of Search: 347236-237, 347246-247, 347132-133, 347/140, 399/44, 399 47- 51, 399 94- 96, 399127-128
• US Class Current: 347/236
• CPC Class Codes: B41J 2/45 using light-emitting diode [LED] or laser arrays
• CPC Class Codes: G03G 15/043 with means for controlling illumination or exposure G03G15/041 takes precedence
• CPC Class Codes: G03G 2215/0478 due to image carrier variations, e.g. ageing

Abstract

With a control device to optimize charge image generation in an electrophotographic process, a light-sensitive and temperature-sensitive photoconductor layer is exposed pixel-by-pixel with a temperature-sensitive light source. The photoconductor layer becomes more sensitive with rising temperature, such that given a predetermined light quantity it discharges deeper. With rising temperature, given the same actuating power, the light source emits a lesser luminous power. The luminous power of the light source and the discharge depth of the photoconductor layer are temperature-dependent via adjustment of the current and/or the luminous duration that flows through the light source and/or the luminous duration. During the measurement of the discharge depth, a temperature measured in the course of the measurement event is used as a reference value for the temperature compensation of the light source.

Claims

1. A control device to optimize load image generation in an electrophotographic process, comprising:

a light-sensitive and temperature-sensitive photoconductor layer for pixel-by-pixel exposure with a temperature-sensitive light source;

the photoconductor layer being more sensitive with rising temperature, such that given a predetermined quantity of light and predetermined charge it discharges deeper;

the light source emitting a lesser luminous power with rising temperature given a same actuation power;

a respective temperature compensation for the light source and for the photoconductor layer;

the temperature compensation for the photoconductor layer being at least one of adapting current flowing through the light source and adapting exposure time of the light source;

the temperature compensation for the light source being at least one of correction of the current flowing through the light source and a change of the exposure time;

for the temperature compensation of the photoconductor layer a measurement event which measures a discharge depth of the photoconductor layer given predetermined luminous duration and predetermined current throuah the light source;

a temperature of the light source measured in the course of the measurement event being used as a reference value for the temperature compensation of the light source; and

light energy of the light source being held constant between successive discharge depth measurements.

2. The control device according to claim 1 wherein the temperature-dependent regulation of the light source occurs via the current flowing through the light source, whereby in a calculating unit, as a function of a variation of the reference temperature, a correction term is introduced that effects a predetermined light energy change, the correction term being discontinued when the measurement of the discharge depth occurs.

3. A control device to optimize load image generation in an electrophotographic process, comprising:

a light-sensitive and temperature-sensitive photoconductor layer for pixel-by-pixel exposure with a temperature-sensitive light source;

the photoconductor layer being more sensitive with rising temperature, such that given a predetermined guantity of light and predetermined charge it discharges deeper;

the light source emitting a lesser luminous power with rising temperature given a same actuation power;

a respective temperature compensation for the light source and for the photoconductor layer;

the temperature compensation for the photoconductor layer being at least one of adapting current flowing through the light source and adapting exposure time of the light source;

the temperature compensation for the light source being at least one of correction of the current flowing through the light source and a chance of the exposure time;

for the temperature compensation of the photoconductor layer a measurement event which measures a discharge death of the photoconductor layer given predetermined luminous duration and predetermined current through the light source;

a temperature of the light source measured in the course of the measurement event being used as a reference value for the temperature compensation of the light source; and

in an operating phase of lesser temperature than a nominal temperature T_limit, a temperature overcompensation occurs for the light source such that the activation power is dynamically superproportionally raised.

4. The control device according to claim 3 wherein a trigger voltage for the luminous power occurs according to a formula

V_{I LED}=V_base+V_corr(T_REF−

T_current)+V_corr(T_limit−

MIN(T_limit;

T_current))

where

V_{I LED}=control voltage

V_base=base voltage

V_corr=temperature coefficient for the luminous power stabilization

T_REF=current reference temperature

T_current=current measured temperature

T_limit=boundary temperature in which the dynamic superproportional luminous power increase ends.

5. A method for optimizing load image generation in an electrophotographic process, comprising the steps of:

providing a light-sensitive and temperature-sensitive photoconductor layer for exposure pixel-by-pixel with a temperature-sensitive light source;

the photoconductor layer becoming more sensitive with rising temperature such that given a predetermined guantity of light and predetermined charge it discharges deeper;

the light source emitting a lesser luminous power with rising temperature given a same actuation power;

providing a respective temperature compensation for the light source and for the photoconductor layer;

providing the temperature compensation for the photoconductor layer by at least one of adapting current flowing through the light source and adapting exposure time of the light source;

providing the temperature compensation for the light source by at least one of correction of current flowing through the light source and change of exposure time;

for the temperature compensation of the photoconductor layer, providing a measurement event in which a discharge death of the ohotoconductor layer is predetermined given predetermined luminous duration and predetermined current through the light source;

using a temperature of the light source measured in the course of the measurement event as a reference value for the temperature compensation of the light source; and

in an operating phase of lesser temperature than a nominal temperature T_limit, a temperature over-compensation occurring for the light source such that the activation power is dynamically increased until the nominal temperature is reached.

6. A method for optimizing load image generation in an electrophotographic process, comprising the steps of:

providing a light-sensitive and temperature-sensitive photoconductor layer for exposure pixel-by-pixel with a temperature-sensitive light source;

the photoconductor layer becoming more sensitive with rising temperature such that given a predetermined guantity of light and predetermined charge it discharges deeper;

the light source emitting a lesser luminous power with rising temperature given a same actuation power;

providing a respective temperature compensation for the light source and for the photoconductor layer;

providing the temperature compensation for the photoconductor layer by at least one of adapting current flowing through the light source and adapting exposure time of the light source;

providing the temperature compensation for the light source by at least one of correction of current flowing through the light source and change of exposure time;

for the temperature compensation of the photoconductor layer, providing a measurement event in which a discharge depth of the photoconductor layer is predetermined given predetermined luminous duration and predetermined current through the light source;

using a temperature of the light source measured in the course of the measurement event as a reference value for the temperature compensation of the light source; and

in an operating phase of lesser temperature than a nominal temperature T_limit, a temperature over-compensation occurs for the light source such that the activation power is dynamically increased superproportionally.

7. A computer program product for optimizing load image generation in an electrophotographic process wherein a light-sensitive and temperature-sensitive photoconductor layer are provided for exposure pixel-by-pixel with a temperature-sensitive light source, the photoconductor layer being more sensitive with rising temperature such that given a predetermined quantity of light and predetermined charge it discharges deeper, and the light source emitting a lesser luminous power with rising temperature given a same actuation power, said computer program product comprising:

a program on a computer readable media; and

said program

providing temperature compensation for the photoconductor layer by controlling at least one of an adaption of current flowing through the light source and an adaption of exposure time of the light source,

providing temperature compensation for the light source by at least one of correcting current flowing through the light source and changing exposure time,

for said temperature compensation of the photoconductor layer controlling provision of a measuring event in which a discharge depth of the photoconductor layer is predetermined given predetermined luminous duration and predetermining current through the light source,

using a temperature of the light source measured in the course of the measurement event as a reference value for the temperature compensation of the light source, and

holding light energy of the light source constant between successive discharge depth measurements.

8. A computer program product for optimizing load image generation in an electrophotographic process wherein a light-sensitive and temperature-sensitive photoconductor layer are provided for exposure pixel-by-pixel with a temperature-sensitive light source, the photoconductor layer being more sensitive with rising temperature such that given a predetermined quantity of light and predetermined charge it discharges deeper, and the light source emitting a lesser luminous power with rising temperature given a same actuation power, said computer program product comprising:

a program on a computer readable media; and

said program

providing temperature compensation for the photoconductor layer by controlling at least one of an adaption of current flowing through the light source and an adaption of exposure time of the light source,

providing temperature compensation for the light source by at least one of correcting current flowing through the light source and changing exposure time,

for said temperature compensation of the photoconductor layer controlling provision of a measuring event in which a discharge depth of the photoconductor layer is predetermined given predetermined luminous duration and predetermining current through the light source,

said computer program using a temperature of the light source measured in the course of the measurement event as a reference value for the temperature compensation of the light source, and

said computer program in an operating phase of lesser temperature than a nominal temperature T_limit, controlling a temperature over compensation for the light source such that the activation power is dynamically superproportionally raised.