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Method of controlling a segmented flash system

a segmented flash and control method technology, applied in the field of controlling a segmented flash system, can solve the problem that the prior art method cannot always generate the correct illumination profile, and achieve the effect of reducing processor load and serial bus load, and efficient managing forward voltage measurement steps

Active Publication Date: 2021-06-24
LUMILEDS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention is a flash driver that can measure the temperature distribution of its flash segments using low constant current conditions. This ensures that the measurement does not disturb the temperature distribution and minimizes energy consumption. The forward voltages of the segments are measured after a certain time has passed following a flash event. The flash driver also includes a state machine for efficient management of the measurement steps, a multiplexer for selecting a specific flash segment, an analog-to-digital converter for converting the measured voltages into digital values, and a storage means for temporarily storing the converted values. The technical effects of this invention include improved temperature measurement accuracy and efficiency in managing the measurement steps.

Problems solved by technology

In a segmented flash, each flash segment can have a different temperature and a different temperature characteristic, and the resulting differences in temperature hysteresis for the various segments means that a prior art method will be unable to always generate a correct illumination profile.

Method used

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  • Method of controlling a segmented flash system
  • Method of controlling a segmented flash system
  • Method of controlling a segmented flash system

Examples

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Embodiment Construction

[0036]FIG. 1 shows a simplified block diagram of an embodiment of the inventive segmented flash system 1. The diagram shows a segmented flash 10, in this case a 5×5 square array of LEDs 100. The LEDs 100 of this array will illuminate twenty-five regions in a scene. In this exemplary embodiment, an illumination profile P can be provided by a depth map module 1B, which may for example compute the illumination profile P using information obtained by a photodetector 4. The illumination profile P specifies the required intensity or power required for each LED 100 to correctly illuminate the scene, assuming an equilibrium condition in which all LEDs 100 have essentially the same temperature. In this exemplary embodiment, the segmented flash system 1 also comprises a voltage measuring module 1A that measures the forward voltages Vf1, Vf2, . . . , Vfn of the LEDs 100 of the array. With this information, a controller 1C computes adjusted drive current values Id1_a, Id2_a, . . . , Idn_a for t...

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Abstract

Systems, methods and devices are descried. A method of controlling a segmented flash having a plurality of flash segments each arranged to illuminate a portion of the scene includes determining an amount of light for illuminating each portion of the scene, measuring forward voltages of each of the flash segments, and adjusting a brightness of each of the flash segments to the determined amount of light for illuminating each portion of the scene. The adjusting is performed by at least one of adjusting a magnitude of a drive current to each of the flash segments, adjusting a duty cycle of the drive current to each of the flash segments, or scheduling a dummy flash, based at least in part on the measured forward voltages.

Description

FIELD OF THE INVENTION[0001]The invention describes a method of controlling a segmented flash system.[0002]The invention also describes a segmented flash system.BACKGROUND OF THE INVENTION[0003]When a conventional flash system is used in photographing a scene, any objects that are too close to the camera may suffer from overexposure and appear too “white” or pale in the image, while objects further away from the camera may not be sufficiently illuminated and appear too dark in the photograph or image. Developments in flash systems have led to a segmented flash, i.e. a flash made up of an array of light sources. The spectra of the light sources deployed in the segmented flash can be chosen to achieve a desired white balance. Each light source illuminates a region of the scene, so that the segmented flash generates an “illumination profile” or pattern. It is possible to determine the relative amount of light required to correctly illuminate or expose each region of the scene, for exam...

Claims

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Application Information

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IPC IPC(8): H05B45/14G03B15/05H05B45/37H05B44/00
CPCH05B45/14H05B45/37G03B15/05H05B45/30H05B45/345G03B15/02H05B45/24H05B45/56G03B2215/0567H05B45/52
Inventor DERKS, HENK
Owner LUMILEDS
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