Industrial Engineering and Ergonomics

Transcription

1 Industrial Engineering and Ergonomics Exercise Unit 11 Computer and Office Work Fall Winter 2016/2017 Dr.-Ing. Dr. rer. medic. Dipl.-Inform. Alexander Mertens Univ.-Prof. Dr.-Ing. Dipl.-Wirt.-Ing. Christopher M. Schlick Chair and Institute of Industrial Engineering and Ergonomics Instructor: Dipl.-Ing. Tobias Hellig Lehrstuhl und Institut für Arbeitswissenschaft, RWTH Aachen

2 Exercise 1 Font size DIN According to DIN , the angular character height must be at least 16 high (absolute minimum for recognition) and should range between 20 and 22 during office work. Calculate the optimal character height for the described office work place. The distance to the display is 75cm. 11-2

3 Exercise 2 Font size DIN Would a symptom-free recognition of screen information be possible with a font height of 7 mm and a viewing distance of 750 mm? Justify your answer. 11-3

4 Exercise 3 Illumination of a projectionist What is the mean luminous intensity of a projectionist with the utilised flux of 120lm when the light cone has a flat angle of 20? The solid angle can be ascribed to the flat angle of aperture ω of the light cone with the following formula: Ω = 2π 1 cos ω 2 sr 11-4

5 Exercise 4 Lighting in an Engineering Office An engineering office (length = 5 m, width = 4 m) is equipped with three luminaires. Each luminaire contains two lamps. The main task performed in this office is to work on technical drawings. The nominal luminous flux of each lamp amounts to 3200 lm, aging and dirt of the lamps have to be taken into account by a decrease in the demanded nominal illuminance of 25 %. 1. Check whether the requirements to the demanded nominal illuminance according to DIN in Table 1 are met. Take into account the aging and dirt of the lamps. 11-5

6 Exercise 4 Lighting in an Engineering Office Recommendations for illuminance E, each in lx Task assembly work rough medium-fine precise very precise E (Lux) body construction and assembly work 500 general engine work 300 production of tools and cutlery 750 technical drawing 750 office work sorting, duplicate, etc. write, read, data processing daylight daylight among the shades bright daylight

7 Exercise 4 Lighting in an Engineering Office A = length = 5 m, width = 4 three luminaires containing two lamps each with 3200lm Technical drawings: E = 750 lux minimum 25% decrease by dirt 11-7

8 Exercise 5 Lighting in a machinery hall A machinery hall with an area of 125 m 2 is used for rough work on a toolmaking machine. The hall is illuminated by 16 lamps with 2 fluorescent lamps each. Each of these fluorescent lamps emits a luminous flux of Φ=2100 lm. The solid angle amounts Ω=1.1 sr. In the future, it is planned to also use the machine hall for very precise work on toolmaking machines (750 lux). Therefore, a modification of the illumination in the machine hall should take place. 1. Determine the maximal possible illuminance E within the machinery hall. Give the result in Lux. 2. Does the calculated illuminance fulfill the requirements? 3. Calculate the luminous intensity I per fluorescent lamp. Give the result in Candela. 4. Which technical changes are necessary? Please explain two reconstruction possibilities by mathematical proof. Therefore, calculate the necessary redesign of the workplace. 11-8

9 Exercise 5 Lighting in a machinery hall Recommendations for illuminance E, each in lx Task assembly work rough medium-fine precise very precise E (Lux) body construction and assembly work 500 general engine work 300 production of tools and cutlery 750 technical drawing 750 office work sorting, duplicate, etc. write, read, data processing daylight daylight among the shades bright daylight

10 Exercise 6 Lighting in a machinery hall Next to the machine hall, there is an office with two computer work stations. Each computer work station consists of a working area A B =2 m 2 and is illuminated by a desk lamp. Each desk lamp emits a luminous flux of Ф=3100 lm. The solid angle amounts Ω=1.2 sr. 1. Calculate the luminance L which is generated on top of the working area A B. Give the result in Candela per m

11 Exercise 7 Lighting a Watchmaker s workplace A work desk in a watchmaker s workshop has to be designed. The luminaire should be arranged perpendicularly above the workplace. The work space amounts 80 cm x 60 cm, the average reflectance is 40 %. The demanded nominal illuminance is 1500 lx. Diffuse surface (Lambertian): L = E p 11-11

12 Exercise 7 Lighting a Watchmaker s workplace 1. Determine the required luminous flux to radiate the workplace. 2. What is the maximal perceivable luminance of the work surface? Assume that the surface emits or reflects luminous flux in such a way that it has the same luminance regardless of viewing angle (Lambertian)

13 Formulary Lumen (lm) = I * Mean Luminous Intensity (cd) I = Illuminance (Lux = Lumen/m²) I E = = = A A I 2 r Luminance (cd/m²) L = I A Reflectance (ρ) = r 11-13