The requirements for the stability of the dimming method of stage lights

The requirements for the stability of the dimming method of stage lights

The dimming stability of stage lights directly affects the performance effect, especially in light gradients, color transitions and dynamic scenes. Dimming fluctuations, flickering or delays may cause visual discomfort to the audience or disrupt the performance atmosphere. The following analysis is conducted from four dimensions: the principle of dimming technology, core stability indicators, testing methods, and purchasing strategies.

First, the principle of dimming technology is related to stability

PWM (Pulse Width Modulation) dimming

Principle: The brightness is controlled by rapidly switching the current. The higher the frequency (such as ≥1kHz), the more difficult it is for the human eye to detect the flickering.

Stability risk

Low-frequency PWM (<500Hz) may cause stroboscopic effects, especially at low brightness.

Design flaws in the driving circuit may cause current fluctuations, resulting in brightness jitter.

Case: In a drama performance, if low-frequency PWM dimming lamps are used, the actors' faces may show "striped flickering", which can damage the texture of the picture.

Analog dimming (0-10V/DMX linear dimming)

Principle: The brightness changes are achieved by continuously adjusting the voltage or current, and theoretically, there is no flicker.

Stability risk

Power fluctuations or load changes may cause brightness drift.

Nonlinearity of the dimming curve may cause sudden changes in brightness.

Case: In a concert, if the dimming curve of the simulated dimming fixtures is not calibrated, the gradual change process may experience brightness jumps, which can affect emotional expression.

Hybrid dimming (PWM+ Analog)

Principle: Combining high-frequency PWM and analog dimming, it takes into account both flicker-free and dimming accuracy.

Stability advantage:

High-frequency PWM eliminates visible flicker, and simulated dimming optimizes low-brightness smoothness.

It needs to be combined with a high-precision drive circuit and a temperature compensation algorithm.

Case: In immersive performances, hybrid dimming fixtures can achieve a step-by-step gradient from total darkness to high brightness, enhancing the visual immersion.

Second, the core indicator of dimming stability

Dimming fluctuation depth (SVM)

Definition: An index for measuring the fluctuation range of brightness. When SVM≤0.4, the flicker is difficult to be detected by the human eye.

Test method: Use a stroboscopic analyzer to measure the SVM values of the lamps at different brightness levels.

Requirement:

Fast-paced performances (such as concerts) : SVM≤0.2.

Slow-paced performances (such as dramas) : SVM≤0.4.

Dimming linearity

Definition: The degree of matching between the brightness variation and the control signal (such as the DMX value).

Test method: Send DMX values ranging from 0 to 255 through the console and record the actual brightness variation curve.

Requirement:

The linear error is ≤5% (to avoid sudden changes in brightness).

The low-brightness area (<10%) needs to be specially optimized to prevent brightness jitter.

Dimming response time

Definition: The time from receiving the control signal to the luminance reaching the target value.

Test method: Use an oscilloscope to measure the delay between the PWM signal and the brightness variation.

Requirement:

Fast dimming (such as stroboscopic) : ≤50ms.

Gradient dimming: 100-500ms (adjusted according to the performance rhythm).

Temperature stability

Definition: The situation where the dimming performance of a lamp changes with temperature after long-term operation.

Test method: Let the lamp run continuously at high brightness for 2 hours, and measure the changes in dimming fluctuation depth and linearity.

Requirement:

When the temperature increase is ≤30℃, the change of SVM is ≤0.1.

The dimming linearity error is ≤3%.

Third, the testing and verification methods for dimming stability

Laboratory test

Stroboscopic analysis: Use a stroboscopic analyzer to measure the SVM values at different brightness levels and verify whether they meet the standards.

Dimming curve calibration: Send the DMX value through the console, record the brightness change curve, and optimize the dimming linearity.

High-temperature aging test: Simulate the long-term operation of lamps in a high-temperature chamber to monitor the attenuation of dimming performance.

Case: During the research and development stage, a high-temperature aging test was conducted on a certain model of lamp. It was found that the SVM rose from 0.3 to 0.6 at 50℃, and the heat dissipation design needs to be improved.

On-site simulation

Rhythm synchronization test: Play music of different rhythms, send dimming commands manually or through the console, and observe whether the brightness changes are synchronized with the music.

Multi-lamp linkage test: Control multiple lamps simultaneously to check the consistency and synchronization of dimming.

Audience feedback: Invite non-professional audiences to evaluate whether the dimming is natural to avoid discomfort caused by brightness jitter or flicker.

Case: At a certain music festival, due to inconsistent dimming response times of some lamps, a "wave effect" occurred when the lights in the entire venue gradually changed, affecting the performance effect.

Long-term stability test

Continuous operation test: Let the lamp run continuously for 24 hours, and record the depth of dimming fluctuation and linearity every 2 hours.

Mechanical durability test: Repeatedly adjust the dimming knob or use the console to send instructions to check for any lag or failure.

Case: After continuous operation for 12 hours, a certain model of lamp showed brightness jitter in the low-brightness area. The design of the driving circuit needs to be improved.

Fourth, the demand for dimming stability in different performance scenarios

Fast-paced performances (such as concerts, electronic music festivals)

Requirements: Ultra-low latency, no flicker, and high brightness consistency.

Purchasing suggestions:

Choose lamps that support high-frequency PWM dimming (≥1kHz).

The test SVM value is ≤0.2 and the dimming response time is ≤50ms.

Give priority to adopting the hybrid dimming technology, taking into account both flicker-free and dimming accuracy.

Case: In a certain electronic music festival, high-frequency PWM dimming lamps were used to achieve real-time synchronization between the lighting and the DJ's recording.

Slow-paced performances (such as dramas and ballets)

Requirements: Smooth gradient, low-brightness stability, and natural color transition.

Purchasing suggestions:

Select lamps with dimming linearity error ≤3%.

Test the brightness jitter in the low-brightness area (<10%).

Priority support for 16-bit DMX dimming to enhance gradient accuracy.

Case: In a certain play, lamps with optimized dimming linearity were used to achieve a natural gradient of light on the actors' faces.

Immersive performances (such as holographic projections, interactive installations)

Requirements: Ultra-long gradient, precise positioning, and synchronization of multiple lamps.

Purchasing suggestions:

Select lamps that support the Art-Net protocol to reduce the delay of control signals.

The dimming synchronization error of multiple lamps in the test is ≤5ms.

The temperature compensation algorithm should be given priority to avoid the attenuation of dimming performance after long-term operation.

Case: In a certain holographic performance, lamps supporting the Art-Net protocol were used to achieve precise synchronization of the entire venue's lights and projections.

Fifth, precautions when making a purchase

Clarify the dimming requirements

Determine the dimming stability index according to the performance type. For example, for a fast-paced performance, priority should be given to the SVM value and dimming response time.

To avoid blindly pursuing high indicators, it is necessary to balance performance and cost.

Verify the dimming technology

Confirm the dimming technology adopted by the lamps (such as PWM, analog or hybrid dimming), and test its actual effect.

Give priority to choosing lamps that support mixed dimming, taking into account both flicker-free and dimming accuracy.

Test long-term stability

Through continuous operation tests and high-temperature aging tests, verify whether the dimming performance of the lamps has declined over time.

Pay attention to the heat dissipation design and the quality of the drive circuit to avoid dimming fluctuations caused by overheating.

Check compatibility

Ensure that the lamps support mainstream control protocols (such as DMX512, Art-Net) and are compatible with existing consoles and software.

Test the dimming synchronization when multiple lamps are linked to avoid the "wave effect".

Sixth, Summary and Suggestions

Core principle: The dimming stability of stage lights should be highly matched with the performance rhythm and scene requirements to avoid spoiling the performance atmosphere due to dimming fluctuations, flickering or delays.

Selection method:

Determine the dimming stability indicators (such as SVM value, dimming linearity, and response time) based on the performance type.

The dimming performance of the lamps was verified through laboratory tests and on-site simulations.

Pay attention to the dimming technology, heat dissipation design and compatibility of the lamps to ensure their long-term stable operation.

Optimization strategy:

Fast pace: Select high-frequency PWM dimming lamps to ensure no flicker and ultra-low latency.

Slow rhythm: Select lamps with optimized dimming linearity to achieve smooth gradients and low-brightness stability.

Immersive performance: Select lamps that support the Art-Net protocol to ensure the synchronization and precise control of multiple lamps.