| 摘要: | 本研究探討使用LED檯燈輔助照明時，中心照度、中心照度與背景照度間之對比度以及受試時間對人眼視覺舒適度、閱讀工作績效的影響，分兩部份實驗進行。實驗第一部分是高中心照度低對比度實驗，有36位受試者參與，年齡介於18至25歲。實驗自變項為：中心照度(1000、1500、2000 lux)、對比度(1:0、4:1、3:1、2:1)、受試時間(早上、下午、晚上)。實驗第二部份是低中心照度高對比度實驗，有45位受試者參與，年齡介於18至25歲。實驗自變項為：中心照度(100、200、500、750、1000 lux)、對比度(10:1、5:1、2:1)、受試時間(早上、下午、晚上)。兩部份實驗依變項皆為視覺舒適度主觀評量、閱讀之圈字正確率。 實驗結果顯示：使用LED檯燈時，閱讀工作區的照度至少必須在500 lux以上才能有優良的視覺舒適度，但照明水準達1000 lux就已十分充足，無須再追求更高照度；使用檯燈時務必要搭配背景燈，且中心照度與背景照度之比值建議2:1為最佳選擇，若基於節能考量可採用4:1或5:1的設計；除非十分強調工作績效表現，否則不需分別訂立各時段之照明水準；受試者閱讀之圈字正確率與工作區中心照度提升無顯著關係，但圈字數目在對比度高時，即背景光較暗、受試者必須藉由中心照度閱讀的情況下，中心照度要在500 lux以上才有好的表現，這部份和本研究視覺舒適度的結果相符。本實驗證明唯有兼顧中心照度與背景光的搭配，才能營造舒適、恰當的照明環境。 The purpose of this study was to evaluate visual comfort and task performance of LED desk lamp users when reading under different central illuminance levels, with various contrast ratios between the central and ambient illuminance, and at different test time. The experiment was implemented in two parts. The first part is the high-central-illuminance and low-contrast experiment. Thirty-six subjects participated in this study voluntarily, and their ages ranged from 18 to 25 years old. The independent variables were the central illuminance (1000, 1500, or 2000 lux), the contrast ratio between the central and ambient illuminance (1:0, 4:1, 3:1, or 2:1) and the test time (morning, afternoon, or night). The second part is the low-central-illuminance and high-contrast experiment. Forty-five subjects participated in this study voluntarily, and their ages ranged from 18 to 25. The independent variables were the central illuminance (100, 200, 500, 750, or 1000 lux), the contrast ratio (10:1, 5:1, or 2:1) and the test time (morning, afternoon, or night). The dependent variables were the subjective visual comfort rating and the correct ratio of word-labeling in both parts. The results indicated that when reading with a LED desk lamp, the central illuminance must be at least 500 lux to achieve satisfactory visual comfort. A central illuminance level of 1000 lux is sufficient for reading, and thus there is no need to pursue much higher illuminance for LED desk lamps. In addition, it is important to have ambient lighting when using desk lamps. Based on the experimental results, the best contrast ratio between the central and ambient illuminance is 2:1. If energy saving is highly demanded, 4:1 or 5:1 are also appropriate choices. It is not necessary to establish individual illuminance suggestions for different time during the day, unless the task performance is extremely important. The correct ratio of word-labeling was not affected by the independent variables, but the number of labeled words was influenced by the central illuminance when the contrast was high. When the ambient was relatively dark, the central illuminance must be higher than 500 lux for good task performance. This result coincided with the outcome of the visual comfort experiment. According to the research results, comfortable lighting environments could only be realized when the central and ambient illuminance is appropriately collocated. |
