With the increasing demand for accurate display measurements, the significance of viewing angle in achieving display accuracy cannot be overlooked. Transmissive illuminated displays require direct contact or close proximity between the meter and the screen to avoid any shadows cast by the meter. Off-angle light or gain differential can lead to inaccuracies, necessitating the reading of luminous patterns rather than the surrounding black area. However, there is a lack of clear specifications for viewing angles in meters, making it imperative to conduct tests to determine the appropriate angles. The shape of the light response in meters typically follows a Gaussian curve or a plateau shape, with wider Gaussian responses being more vulnerable to off-angle light. The Full-Width Half Max Angle (FWHM) is the most relevant number for meter placement, encompassing the majority of meter sensitivity. Additionally, the Total Light Termination Angle (TLT) is considered but to a lesser extent than FWHM. This article aims to explore the significance of viewing angle in display accuracy, examining the importance in transmissive displays, the lack of specifications in meters, the shape of light response, and the ambiguity in meter specifications, among other key factors.
Key Takeaways
- Viewing angle is important in transmissive illuminate displays to avoid shadow cast by the meter and minimize inaccuracies from off-angle light or gain differential.
- Lack of clear specifications for viewing angle in meters makes it necessary to run own tests to determine viewing angles, considering attributes such as full width at half max angle, total light termination angle, and shape of light response.
- The shape of light response in meters can be a plateau shape with a flat maximum response range or a Gaussian curve with a smooth transition from zero to maximum response. The wider the Gaussian response, the more susceptible it is to off-angle light.
- The Full-Width Half Max Angle (FWHM) is the most relevant number for meter placement as the majority of meter sensitivity is within this angle. The Total Light Termination Angle (TLT) is also considered, but less important than FWHM.
Importance in Transmissive Displays
The importance of viewing angle in transmissive displays is highlighted by the need to avoid shadow cast by the meter, minimize inaccuracies from off-angle light or gain differential, and read only from the luminous pattern, not the surrounding black area, all of which can compromise meter placement. Direct contact or close proximity between the meter and screen is essential to ensure accurate readings. By avoiding shadows, the meter can capture the true luminous pattern of the display without any interference. In addition, minimizing inaccuracies caused by off-angle light or gain differential is crucial to maintain display accuracy. This requires careful placement of the meter to ensure that it is positioned at the optimal viewing angle. By reading only from the luminous pattern and not the surrounding black area, the meter can provide precise measurements and avoid any distortions caused by extraneous factors. Overall, understanding and considering the viewing angle is paramount in achieving accurate and reliable measurements in transmissive displays.
Lack of Specifications in Meters
Ambiguity persists in meter specifications due to the absence of clear guidelines. The lack of specific information regarding viewing angles in meters poses a challenge for users. Manufacturers often provide specifications based on ideal conditions, leaving users to conduct their own tests to determine the viewing angles. Three relevant attributes for determining viewing angles are the full width at half max angle (FWHM), total light termination angle (TLT), and shape of the light response curve. The FWHM angle is the most important number for meter placement as it represents the width of the Gaussian curve halfway between minimum and maximum sensitivity. The TLT angle indicates when the meter stops reading any light. When FWHM and TLT are close, the response curve is plateau-like, while wider separations indicate a Gaussian curve. Clear guidelines and standardized specifications are necessary to ensure accurate and reliable meter placement.
Shape of Light Response
One aspect to consider when evaluating meters is the shape of their light response curve, which can vary between a plateau shape with a flat range of maximum response and a Gaussian curve with a smooth transition from zero to maximum response. The shape of the light response curve is important because it affects the meter’s susceptibility to off-angle light. Meters with a wider Gaussian curve are more susceptible to off-angle light and may provide less accurate readings. On the other hand, meters with a plateau shape have a flat range of maximum response, which allows for better representation of the display as a whole. Additionally, meters with a wider field of view, resulting from a Gaussian curve, can provide better accuracy. Therefore, understanding the shape of the light response curve is crucial when considering meter accuracy and performance.
Full-Width Half Max Angle (FWHM)
A crucial factor to consider when evaluating meters is the Full-Width Half Max Angle (FWHM), which represents the width of the Gaussian curve halfway between its minimum and maximum points. The FWHM angle is the most relevant number for meter placement as it determines the majority of the meter’s sensitivity. Within this angle, approximately 85 to 90 percent of the light is read by the meter. By knowing the FWHM, one can determine the optimal position for the meter. Meters with a wider FWHM angle are more susceptible to off-angle light, which can result in inaccuracies in the readings. Therefore, meters with smaller FWHM angles provide better control over meter placement, ensuring a more accurate representation of the display as a whole. Additionally, meters with a wide field of view offer better accuracy in capturing the full range of the display.
Total Light Termination Angle (TLT)
The Total Light Termination Angle (TLT) is another important consideration when evaluating meters, as it represents the angle at which the meter stops reading any light. While the Full-Width Half Max Angle (FWHM) is the most relevant number for meter placement, the TLT provides additional information about the shape of the meter’s light response curve. When the FWHM and TLT angles are close together, the meter’s response curve resembles a plateau, indicating a flat maximum response range. On the other hand, when the FWHM and TLT angles are farther apart, the response curve takes on a wider Gaussian shape, making the meter more susceptible to off-angle light. Therefore, the TLT helps determine the overall shape of the meter’s light response and can inform meter placement decisions.
Ambiguity in Meter Specifications
Ambiguity arises in meter specifications due to the various ways in which the meter read angle is listed, such as the center-to-edge angle or full angular field. This lack of uniformity in specifying the viewing angle can be confusing for users. Some meters provide the full angular field, representing the diameter of the read area, while others specify the angle at which a certain percentage of light is read, such as the Full-Width Half Max Angle (FWHM). This inconsistency makes it difficult for users to compare and determine the size of the read area at different distances. To address this issue, clear and standardized specifications for meter viewing angles need to be established. This will enable users to accurately assess the suitability of a meter for their specific needs and ensure consistent and reliable display accuracy.
Calculation of Read Area Diameter
Calculation of the diameter of the read area can be determined by using an equation that takes into account the distance between the meter and screen, as well as the total viewing angle, allowing for precise measurement and placement of the meter. To calculate the read area diameter, follow these steps:
- Measure the distance between the meter and the screen using a tape measure for accurate results.
- Determine the total viewing angle of the meter, which can be found in the specifications provided by the manufacturer.
- Use the equation: Read Area Diameter = 2 Distance tan(Viewing Angle/2) to calculate the diameter of the read area.
- Ensure that the calculator is set to degrees rather than radians for accurate calculations.
By using this equation, the diameter of the read area can be determined precisely, enabling optimal placement of the meter for accurate measurements. This calculation method allows for greater precision and control in meter placement, ensuring reliable and innovative display accuracy.
Aiming Systems in Meters
Moving on from the calculation of the read area diameter, another aspect to consider in meter placement is the presence of aiming systems in some meters. These aiming systems, such as the ones found in meters like the K-10, Discus, and Hubble, are designed to assist in accurately positioning the meter for measurements. The K-10 meter, for instance, passes its aiming lights through the same optics used for measurement, allowing for an exact visual representation of what the meter is reading. On the other hand, the Discus meter has a center aiming laser offset by 3cm from the lens, which is generally disregarded for projector calibration. The Hubble meter, meanwhile, employs aiming lights from a laser positioned above the prime lens, resulting in a slight difference between what is read and what is displayed. These aiming systems provide additional guidance for precise meter placement, ensuring accurate and reliable measurements.