Vehicle Display Device Brightness Stabilization
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Solution Overview
Problem
Conventional display devices for vehicles using digital micro-mirror devices (DMDs) experience irreversible bright spot defects and reduced lifespan when operated in high temperature environments, leading to unpleasant brightness changes that affect the driver's experience.
Innovation Solution
A display device with a light source capable of emitting multiple colors, a field sequential color control unit, and a spatial light modulation element that adjusts the ON and OFF drive periods of pixels to maintain equal load on the mirrors, thereby prolonging the display element's life and stabilizing brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the display period ratio is changed to balance ON and OFF drive periods of DMD mirrors, then the lifespan of the display element is improved, but the brightness of the display image changes causing unpleasant sensation
Solution Approach 1:
The patent changes the drive current value of the light source as a compensating parameter when the display period ratio is adjusted. By increasing the drive current when the display period is reduced, the light output is maintained, thereby preserving display brightness while still achieving balanced ON/OFF drive periods for the DMD mirrors to extend lifespan
Solution Approach 2:
The control unit monitors the display period ratio and automatically adjusts the drive current value in response. This feedback mechanism ensures that any brightness changes resulting from display period ratio adjustments are compensated, maintaining consistent display quality while protecting the display element lifespan
2Reliability
If the drive period of light source is decreased to balance mirror drive periods, then the occurrence of bright spot defects is reduced, but the display brightness may become insufficient
Solution Approach 1:
When the drive period is decreased to reduce bright spot defects, the patent simultaneously increases the drive current value to compensate for the reduced illumination time. This parameter adjustment maintains the overall light output and display brightness while achieving the reliability improvement of reduced bright spot defects through more balanced mirror actuation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prolongs the lifespan of the display element and prevents unpleasant brightness changes, reducing the occurrence of bright spot defects and maintaining consistent display quality even in high temperature conditions.
Implementation Method 1
a light source configured to be able to emit light of a plurality of colors
Implementation Method 2
a spatial light modulation element which is provided with a plurality of pixels for performing at least ON drive for spatial modulation of light from the light source
Data Source
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AI summary
Provided is a display device for a vehicle such that the life of display elements can be made long even when used in a high temperature environment and, further, unpleasant sensations due to changes in brightness of display images can be prevented. A control unit (90) provides a display period (Fa) in which an illumination control unit (91) turns on light sources (11), and a display control unit (92) generates a display image (M) in display elements (30) within a frame (F) that constitutes the display image (M) on the basis of a display image signal and a non-display period (Fb) in which the illumination control unit (91) turns off all light sources (11). When the display control unit (92) changes the display period proportions (A) for mirrors (E) for the display elements (30) according to prescribed conditions, drive currents (I) and drive periods (H) for the light sources (11) are changed simultaneously such that brightness is not changed.