Method and apparatus for detecting and compensating light emission from an LED array
US4897672A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 23, 1988 |
| Grant date | Jan 30, 1990 |
| Priority date | — |
| Expiry date | Jun 23, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K15/027
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A checking method for a device having a plurality of light emitting elements, especially an LED array installed in electronic printing equipment. The check is done while the LED array is mounted in the equipment and does not require removal thereof. The check is done in a short time period, so it can be done during a period of page change of the printer, without disturbing the operation of the printer. Each of the LEDs are lighted one by one with a pulse. The output emission of the array is detected by a photoelectric detector which is positioned to detect the emission from any of the LEDs. The output of the detector becomes a burst of pulses, each of the pulses representing the emission property of a corresponding LED. Each pulse is converted into a digital signal and stored in a RAM as emission data. The emission data is fed back to the driver of each LED to compensate for differences in the emission characteristics of the LEDs. This improves the uniformity of the output image the electronic printer. Each time of the check is performed, the RAM is rewritten. Thereby, a change in the emission data indicates a change or degradation of one or more of the LEDs. This enables one to fo…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.