Method of correcting the amounts of emitted light

• US 6,100,913 A
• Filed: 05/07/1997
• Issued: 08/08/2000
• Est. Priority Date: 05/10/1996
• Status: Expired due to Fees

• Current Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Original Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Inventors: Aikoh, Yoshihisa, Teshima, Minoru
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nguyen, Lamson D.
• Application Number:
  US08/852,457
• Time in Patent Office: 1,189 Days
• Field of Search: 347/237, 347/238, 347/130, 347/246, 347/247
• US Class Current: 347/237
• CPC Class Codes: B41J 2/45 using light-emitting diode [LED] or laser arrays
• CPC Class Codes: G06K 15/1247 using an array of light sources, e.g. a linear array

Abstract

A method is used for correcting amounts of light of light emitting elements. A first correction range is defined which has a median of maximum and minimum values of the amounts of light of the light emitting elements, and includes a predetermined number of first subdivided ranges. If the minimum amount of light is not within the first correction range, a second correction reference is produced which is smaller than the first correction reference by a predetermined fraction of the difference between the maximum and minimum values. Then, a second correction range is defined which includes the minimum amount of light, has the second correction reference in its middle, and includes a predetermined number of second subdivided ranges. The amounts of light are corrected by increasing the amount of light if the measured amount of light is smaller than the second correction reference and decreasing the amount of light if the measured amount of light is larger than the second correction reference, the amounts of light being increased or decreased by the correction value corresponding to the second subdivided range. The first correction range may be set to include the minimum and maximum values therein, and the first and second subdivided ranges may progressively widen as the first subdivided ranges becomes increasingly far away from the first correction reference.

Claims

1. A method of correcting an amount of light emitted from each of a plurality of light emitting elements, comprising the steps of;

measuring the amount of light emitted from each of the plurality of light emitting elements and determining a minimum value and a maximum value thereof;

defining a first correction reference on the basis of the amount of light emitted from each of the plurality of light emitting elements;

defining a first correction range having an upper limit and a lower limit, the first correction reference being substantially in the middle of the first correction range, the first correction range including a predetermined number of first sub-divided ranges between the upper limit and the lower limit, the first correction range being such that a first difference between the first correction reference and the amount of light emitted from each of the plurality of light emitting elements in the first correction range falls within a first predetermined range;

determining whether the minimum value of the amount of light is within the first correction range;

wherein if the minimum value of the amount of light is within the first correction range, the method further includes the steps of;

determining a first correction value for each of the corresponding first sub-divided ranges, the first correction value being such that the first difference between the first correction reference and the amount of light emitted from each of the light emitting elements in the first correction range after correction is within a second predetermined range; and

correcting the amount of light emitted from each of the light emitting elements in each of the first sub-divided ranges in accordance with the first correction value;

wherein if the minimum value of the amount of light is not within the first correction range, the method further includes the steps of;

defining a second correction range, the second correction range being defined by shifting the first correction range toward the minimum value by a predetermined quantity, the second correction range having a predetermined number of second sub-divided ranges and a second correction reference which is obtained by shifting the first correction reference by the predetermined quantity toward the minimum value;

determining a second correction value for each of the second sub-divided ranges, the second correction value being such that a second difference between the second correction reference and the amount of light emitted from each of the emitting elements in the second correction range after correction is within the second predetermined range; and

correcting the amount of light of each of the light emitting elements in each of the second sub-divided ranges in accordance with the second correction value.

2. The method according to claim 1, wherein the predetermined quantity is a fraction of a difference between the maximum and the minimum values of the amount of light emitted from each of the plurality of light emitting elements.

3. The method according to claim 1, wherein the first correction reference is determined based on the minimum value and the maximum value of the amount of light emitted from the plurality of light emitting elements.

4. The method according to claim 1, wherein the first correction value is for increasing the amount of light emitted from each light emitting element if the amount of light emitted by the respective each light emitting element falling in the first sub-divided range is smaller than the first correction reference;

and

the first correction value is for decreasing the amount of light emitted from each light emitting element if the amount of light emitted by the respective each light emitting element falling in the first subdivided range is larger than the first correction reference.

5. The method according to claim 1, wherein the predetermined quantity is 20% of a difference between the minimum value and the maximum value of the amount of light emitted from the plurality of light emitting elements.

6. The method according to claim 1 wherein the second correction range includes the minimum value.

7. A method of correcting an amount of light emitted from each of a plurality of light emitting elements, comprising the steps of:

measuring the amount of light emitted from each of the plurality of light emitting elements and determining a maximum value and a minimum value of the amount of light thereof;

defining a correction reference on the basis of the amount of light emitted from each of the plurality of light emitting elements;

defining a correction range having an upper limit and a lower limit, the correction reference being substantially in the middle of the correction range, the correction range being such that a difference between the correction reference and the amount of light emitted from each of the plurality of light emitting elements in the correction range falls within a first predetermined range, the correction range including a predetermined number of sub-divided ranges;

determining a correction value for each of the sub-divided ranges, the correction value being such that the difference between the correction reference and the amount of light emitted from each of the emitting elements in the correction range after correction is within a second predetermined range, the sub-divided ranges having progressively larger size as the upper limit and the lower limit of the correction range are approached; and

correcting the amount of light from each of the light emitting elements in each of the sub-divided ranges in accordance with the correction value.

8. The method according to claim 7, wherein the sub-divided ranges have a first size if they are between the correction reference and a first predetermined value of the amount of light from each light emitting element, and a second size larger than the first size if the sub-divided ranges are not between the correction reference and the first predetermined value of the amount of light from each light emitting element.

9. The method according to claim 7, wherein the correction range includes the minimum and maximum value.

10. The method according to claim 7, wherein the correction reference is determined on the basis of the minimum value and the maximum value of the amount of light emitted from the plurality of light emitting elements.

11. The method according to claim 7, wherein the correction value is for increasing the amount of light emitted from each of the light emitting elements if the amount of light emitted by each respective light emitting element falling in the sub-divided range is smaller than the correction reference;

and

the correction value is for decreasing the amount of light emitted from each of the light emitting elements if the amount of light in the sub-divided range is larger than the correction reference.