LEDs for automotive LCD backlighting

Display devices have been used for many years as a means of HMI (Human Machine Interface) to connect humans and machines interactively, and their usage are still expanding.
Automotive interiors are no exception to this trend, with an increasing amount of information being displayed,ranging from important information for safe driving to entertainment information, and this trend will continue to evolve further in the future.

Interior Display Trends The quality of white light Difference in Light Quality LCD backlight structure Product Lineup

Interior Display Trends

Conventional Display

Conventional Display

The cluster meter has an analogue meter with a partial display device, which displays information such as ODD/TRIP and vehicle status in a simplified informaiton.The centre display is used as an infotainment device that can display video and music playback information in addition to navigation.
Current Display

Current Display

Larger displays have increased the amount of information displayed, accelerating their use in entertainment. In addition, the display will be increasingly integrated with air conditioner controls and other operating functions, expanding its role as an HMI device that integrates display and operation. Cluster meters will also be able to display detailed vehicle information and navigation.
Future Display

Future Display

Display sizes will be even larger, with wide P2P displays (Pillar to Pillar) and panoramic HUDs spreading across the dashboard and windshield.Not only does the large screen improve the user experience, but it also promotes personalization, such as control of the display according to the user, such as driver's seat, front passenger seat, etc. Balancing increased information volume with safe visibility will be a challenge, requiring technologies that address both improved visibility and control of displayed information.

The quality of white light

The LCD (Liquid Crystal Display) screen of a meter or entertainment system is a full-color display, with white LED backlight light passing through the LCD's color filter (the three primary colors of light: R: red, G: green, and B: blue).Even if the display device (LCD) is the same, the light source used for the backlight changes the display quality and power consumption characteristics.

Example of spectral distribution of normal white Blue light + yellow phosphor

Example of spectral distribution of normal  white Blue light + yellow phosphor

| Normal White LEDs |
Normal white LEDs achieve white light by mixing blue LED light with yellow phosphor. They feature low power consumption due to their extremely high efficiency in converting power into light, and are relatively inexpensive due to the small number of constituent materials used.On the other hand, the red light component is small, so the coloring performance of the red area when transmitted through an LCD is not high.

Example of spectral distribution of wide gamut white Blue light + green phosphor + red phosphor

Example of spectral distribution of wide gamut white Blue light + green phosphor + red phosphor

| Wide Color Gamut White LED |
White light is achieved by mixing blue LED light with green and red phosphors.The LED light component matches the LCD color filter, resulting in particularly vivid coloring around the red area, expanding the color gamut and improving the quality. On the other hand, the power consumption tends to increase due to the lower power-to-light conversion efficiency compared to normal white LEDs.

Difference in Light Quality

White light from the backlight can be seen as a color image by passing through the LCD and color filter.

| Normal white light |
Normal white light with blue light + yellow phosphor has a low red component light, so red and reddish dislpay on the screen may appear dull.

| Wide gamut white light |
Wide gamut white light with blue light + green phosphor + red phosphor makes screen colors look more vivid than normal white light because of its high red component.

Difference in Light Quality

LCD backlight structure

LCDs are made visible as a luminescent display by transmitting light from the back of the LCD through the backlight. The following describes two typical layout for LEDs, which are the light source of the backlight, used in automotive applications.



LED light is emitted from the side to the light guide plate placed under the LCD, and the light is extracted from the plate upward (toward the user). 
• The entire backlight emits light from the surface. 
• Relatively small number of LEDs to be used = low power consumption
• Less uneven brightness and uniform appearance (The backlight also emits light even in areas where there is no display.)



A method in which LEDs are placed directly under the LCD display and light is directed toward the user.
• Aggregation of area emission of each LED
• The number of LEDs increases depending on the display size and the illumination area of each LED.
• The brightness of the entire display can be increased according to the number of LEDs.

Local dimming technology
• By controlling light emission finely for each area, it is possible to light only necessary areas efficiently.
• High-contrast and high-definition display is possible by de-illuminating areas where there is no display.

Actual display image


Slight light escapes from the unlettered black background, because the light guide plate behind the LCD uniformly illuminate.


The direct local dimming method allows high-contrast, clear viewing without light in areas other than the text.

Areas without lettering display a clear black color because the backlight does not emit any light.

Product Lineup of LEDs for LCD Backlight

We have LED light sources suitable for both edge-lit and direct-lit backlight.
The appropriate light source can be selected according to the application and specifications.

White LEDs for edge-lit /light guide
Type Normal white Wide color gamut white
Product name BXMW115HGSE-100 BXMW115HGSE-200 BXMW115HGSE-300 BXMW115HGSE-400
Luminous flux (lm) 36 50 31.5 44.5
Forward current (mA) 80 120 80 120
Directivity x=115, y=115 x=115, y=115 x=115, y=115 x=115, y=115
Size (L x W x H) 3.2×1.4×0.58 mm 3.2×1.4×0.58 mm 3.2×1.4×0.58 mm 3.2×1.4×0.58 mm
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White LEDs for direct-lit
Under development
Type Wide color gamut white
Product name VLJW115LCS VXFW115JCR VLKW115MCR
Luminous flux (lm) 1.9 6.6 22
Forward current (mA) 3 10 30
Directivity x=115, y=115 x=180, y=180 x=180, y=180
Size (L x W x H) 0.8×0.8×0.56 mm 1.0×1.0×0.95 mm 1.5×1.5×1.40 mm
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*Specifications are subject to change without notice as the product is still under development.

If you have any requests or questions, please feel free to contact us.

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