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SAE J587-2017: License Plate Illumination Devices โ Testing, Requirements, and Design
🛠️ This article provides a professional overview of SAE J587-2017, the standard governing rear registration plate illumination devices. It covers photometry testing, luminance uniformity, material qualifications, and installation guidelines essential for automotive lighting engineers.
Understanding the Standard and Its Scope
SAE J587-2017 specifies test procedures and performance requirements for devices that illuminate a vehicle’s rear license plate. The standard applies to all vehicle types, with specific provisions for motorcycles. Key elements include photometry, color, plastic materials, and installation requirements. Devices may be identified with a lighting identification code ‘L’ per SAE J759.
| Parameter | Requirement | Test Method |
|---|---|---|
| Minimum luminance (all test stations) | ≥ 2.0 cd/m² | Photometry per §5.3 |
| Uniformity ratio (vehicles other than motorcycles) | ≤ 30:1 (max/min) | Figure 1 test plate, 8 stations |
| Uniformity ratio (motorcycles) | ≤ 25:1 (max/min) | Figure 2 test plate, 6 stations |
| Test plate dimensions (vehicles) | 150 × 300 mm | Per §5.3.1.1 |
| Test plate dimensions (motorcycles) | 100 × 175 mm | Per §5.3.1.1 |
| Color of illumination | White per SAE J578 | Color test per §5.2 |
| Plastic optical materials | Shall meet SAE J576 | Per §5.4 and §6.4 |
Identification Code: Devices conforming to this standard may display the code “L” as defined in SAE J759, indicating license plate illumination function.
Critical Testing Procedures
Photometry testing uses a matte white test plate (reflectance 85% ±5% per ASTM E179) mounted at the license plate location, 2 mm from the holder plane. A luminance meter measures each circular test station (see Figures 1 and 2 in the standard). The ratio of maximum to minimum luminance is calculated to ensure uniform illumination.
Other applicable tests are drawn from SAE J575 (vibration, moisture, dust, corrosion, warpage) and SAE J578 (color). Plastic optical parts must comply with SAE J576, with special attention to exposure conditions for shaded or protected mountings.
⚠️ Common Mistake: Engineers often overlook the 13 mm border exclusion zone when designing illumination coverage. Ensure that luminance requirements apply only to the area inside this border.
Design and Installation Best Practices
- Mounting orientation: If the upper edge of the license plate is > 1.2 m from the ground, the plate plane shall be vertical ±15°. If ≤ 1.2 m, the plate shall face between 30° upward and 15° downward from vertical.
- Illumination direction: Devices must be installed so that no white light is projected directly to the rear of the vehicle. Illuminate from the top or sides; bottom illumination is allowed only if supplemented from top or sides.
- Combined functions: If the license plate illumination is integrated with a tail or stop lamp, the combination must meet the requirements for both devices simultaneously.
- Plastic materials: Always validate optical components to SAE J576, especially when devices are in shaded locations that may reduce ultraviolet exposure in real-world use.
Frequently Asked Questions
What is the minimum luminance required at each test station?
Every test station on the applicable test plate must have a luminance of at least 2.0 cd/m² (candelas per square meter).
How is the uniformity ratio calculated?
For vehicles other than motorcycles, the ratio uses the average of the two highest and two lowest luminance values from eight test stations. For motorcycles, it uses the highest value and the average of the two lowest values from six stations. The calculated ratio must not exceed 30:1 or 25:1, respectively.
What standards are referenced for environmental tests?
SAE J587 references SAE J575 for vibration, moisture, dust, corrosion, and warpage tests, and SAE J578 for color testing. Plastic materials must comply with SAE J576.
Can I use any white light source for plate illumination?
The standard requires the light to be white per SAE J578, but also prohibits direct white light emission to the rear of the vehicle. The design must shield or direct the light solely onto the plate area.
