Ergonomic principles for the design of control centres Part 12 : Visual display terminal workstations
Some standard content:
DL/T575.12-1999
This standard is compiled with reference to the contents of visual display terminal (VDT) workstation in the research results of human engineering standardization at home and abroad (see Appendix A). The data related to human body dimensions are determined according to GB10000--88 "Human Body Dimensions of Chinese Adults". This standard comprehensively stipulates the ergonomic requirements for the design and use of visual display terminal (VDT) workstations, and is a comprehensive application of many ergonomic principles on VDT workstations. This series of standards DL/T575 is titled "Guidelines for Ergonomic Design of Control Centers" and includes 12 sub-standards: DL/T575.1 Guidelines for Ergonomic Design of Control Centers Part 1: Terms and Definitions; DL/T575.2 Guidelines for Ergonomic Design of Control Centers Part 2: Field of View and Division of Viewing Areas; DL/T575.3 Guidelines for Ergonomic Design of Control Centers Part 3: Division of Hand Reach and Operation Areas; DL/T575.4 Guidelines for Ergonomic Design of Control Centers Part 4: Dimensions of Confined Spaces; DL/T575.5 Guidelines for Ergonomic Design of Control Centers DL/T575.6 Guidelines for Ergonomic Design of Control Centers Part 6: Principles for the Overall Layout of Control Centers; DL/T575.7
Guidelines for ergonomic design of control center
DL/T575.8Guidelines for ergonomic design of control center Part 7: Layout of control room;
Part 8: Layout and size of workstations;DL/T575.9Guidelines for ergonomic design of control center Part 9: Displays, controllers and interactions;DL/T 575.10
Guidelines for ergonomic design of control center Part 10: Principles of environmental requirements;Guidelines for ergonomic design of control center Part 11: Principles for evaluation of control room;DL/T 575.11
DL/T575.12Guidelines for ergonomic design of control center Part 12: Visual display terminal (VDT) workstation. Appendix A of this standard is a prompt appendix.
This standard was proposed by the former Ministry of Electric Power Industry of the People's Republic of China. This standard is under the jurisdiction of the Power Automation Research Institute of State Power Corporation. The main drafting organizations of this standard are: State Power Corporation Power Automation Research Institute, State Power Corporation Suzhou Thermal Engineering Research Institute, China Standardization and Information Classification and Coding Research Institute.
The main drafters of this standard are: Wu Dangshi, Tong Shizhong, Sheng Jufang, Zhan Jincheng, Ma Changshan, Zhang Jinhua, Hua Donghong, Liu Wei. 1359
1 Scope
Electric Power Industry Standard of the People's Republic of China
Ergonomic principles for the design of control centresPart 12: Visual Display Terminal workstationsDL/T575.12-1999
This standard specifies the basic requirements for ergonomics in the design of visual display terminal (VDT) workstations in control centres. This standard applies to the design and use of VDT workstations, as well as the design of seated workstations with VDT as the main equipment. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. DL/T575.1—1999 Guidelines for ergonomic design of control centers Part 1: Terms and definitions DL/T575.2—1999 Guidelines for ergonomic design of control centers Part 2: Field of view and division of viewing areas DL/T575.8--1999 Guidelines for ergonomic design of control centers Part 8: Layout and dimensions of workstations DL/T575.9—1999 Guidelines for ergonomic design of control centers Part 9: Displays, controllers and interactions DL/T575.10-1999 Guidelines for ergonomic design of control centers Part 10: Environmental requirements Principles 3 Definitions
The definitions adopted in this standard can be found in DI./T575.11999. 4 Overview
The visual display terminal (VDT) workstation is the main equipment in the modern control center, an integration of various elements of the human-machine interface, and the main job for people to monitor and control the operating conditions of the system. A visual display terminal (VDT) is a group of equipment that usually includes a display, keyboard and related electronic control circuits, with or without a central processing unit (CPU); it may also include other input devices and output devices. A VDT can be a terminal of a large system or a computer in its own system. As for printers and communication equipment, they can be placed at the VDT or installed elsewhere for remote control.
A visual display terminal workstation is composed of a VDT as the main body, plus some optional accessories or auxiliary facilities (such as workbenches, chairs, filing cabinets, etc.), and should also include the surrounding working environment. This standard mainly considers displays based on cathode ray tubes (CRTs) and displays based on flat screens. Regarding the latter, the International Organization for Standardization (ISO) is drafting more detailed standards (see Appendix A [37]). 5 Working Environment
This chapter specifies the lighting, noise level and thermal environment requirements for workstations where VDT is used for text processing, data input and data query. Approved by the State Economic and Trade Commission of the People's Republic of China on February 24, 2000 1360
Implementation on July 1, 2000
DL/T575.12—1999
For relevant principles, see DI./T575.10. 5.1 Illumination
The lighting should be bright and uniform enough without glare and flicker. The ambient illumination should ensure the image quality requirements. The illuminance required for the task depends on the visual task being performed. For workstations using VDTs, the illuminance measured on the workbench surface should generally be in the range of 200Ix to 5001x. For active (luminous) displays, at least the contrast requirements specified in 6.13 should be met (some displays can maintain acceptable image quality under very high ambient illuminance). For some passive (light-absorbing) displays, the ambient illuminance may need to be greater than 2001x to meet the brightness requirements specified in 6.12. Ambient illuminance is a combination of general lighting and task lighting. When determining the ratio of the two, consider the display technology used in the job, such as whether it uses a CRT (cathode ray tube) or a ICD (liquid crystal display), or use EI (electroluminescence), or a combination of the above display technologies.
5.2 Glare
Glare increases with the size and brightness of the light source, and decreases with the distance from the light source to the eye. For any visual display surface, the adverse effects of reflected glare should be avoided or reduced as much as possible. The following methods can be used to reduce the impact of glare: a) Reasonable layout of various equipment and light sources in the room so that when people observe the screen, there is no bright light source in the field of vision, and no documents or other light-colored objects are reflected on the display screen; b) Control natural light from windows, for example, use less light-transmitting glass, blinds, sunshades, etc.; c) Use controllable d) Use lighting equipment that can diffuse light to the work station through lampshades or ceilings, walls, etc.; d) Use displays with adjustable screen orientation (such as tiltable or rotatable, and freely positionable) to avoid light; e) Perform anti-glare treatment on the display screen (for example, use a diffuse surface, or apply an anti-reflective coating), or use a filter screen, etc. Anti-glare measures should ensure that the image still meets the brightness and contrast requirements specified in Articles 6.12 and 6.13. Different anti-glare measures should be adopted for different lighting conditions.
5.3 Brightness balance
High-brightness light sources should be avoided in the peripheral part of the field of vision, because high-brightness light sources can cause disabling glare, which will make the characters, symbols or lines displayed on the display become blurred. It is difficult to perceive or identify. When the gaze point quickly shifts from an area of certain brightness to another area of large brightness difference, the contrast sensitivity of the human eye will be temporarily reduced due to the adjustment of the pupil diameter. Therefore, the brightness ratio of two consecutive gaze areas should not be greater than 10:1, so as not to affect the work performance and comfort of the VDT user.
5.4 Glossiness of equipment housing, workbench, and seat surface The surface has a glossy coating, which will produce specular reflection under the irradiation of light and form a glare source. It is recommended that the glossiness of the surface is less than or equal to 45% of the full scale of a 60-degree gloss meter (or equivalent measuring instrument). Small decorations that improve the appearance of equipment or furniture should also meet this requirement.
5.5 Noise
The acoustic design of the workspace should take into account the combined effect of all sound sources. The background noise sound pressure level should be low enough to avoid interference with work activities or conversations; but there should also be appropriate background noise to mask the intrusive sounds from adjacent spaces. It is recommended that the ambient noise sound pressure level should not exceed 55dB (A) (excluding noise generated by users). Impulse noise and audible narrowband noise that are significantly higher than the ambient sound pressure level should be avoided.
5.6 Thermal Environment
The comfort requirements for the thermal environment of a VDT workstation are not significantly different from those of a general office workstation. The following points should be noted: u) The exhaust of each VDT component should not be directed directly toward the user or other personnel's work position; b) The temperature of the external surface that may be occasionally touched during operation should be lower than 50℃: the temperature of the surface touched during normal operation should not exceed 35℃.
℃) The temperature generated by the heat accumulation of the equipment in the knee space of the VDT user below the workbench surface should not be higher than the ambient temperature 1361
3.
6 Visual Display
DL/T575.12---1999
This chapter specifies the technical parameters of visual displays that affect people's work performance and comfort in design and use. For general principles for selecting displays, see DL/T575.91999 5.2.4~5.2.96.1 Design viewing distance
Design viewing distance-generally should not be less than 400mm. For some applications, such as soft key labels on a touch screen, the minimum viewing distance can be reduced to 300mm; the typical viewing distance for reading hard copy is 300mm to 400mm. Comfortable viewing distance is not only related to the size of the characters displayed, but also to the focusing and adjustment ability of the human eye. Different display surfaces that are frequently viewed should be placed at the same or similar viewing distances. If the operation requires clear reading, the design should keep the viewing angle of the character height within the range of 20° to 22'. Figure 1 shows the relationship between character height and viewing distance 6.2 Sight angle of incidence
When observing the display screen from any angle where the angle of incidence is less than or equal to 40° (see Figure 2), the image on the screen should be clear and discernible 1200
Range of best readability
Acceptable range
Character height
Note: The best range in the figure refers to the character height viewing angle of about 20°~22° Figure 1 Relationship between character height and viewing distance (mm) 6.3 Font
Display screen
Figure 2 Sight angle of incidence
The font shape will affect the clarity and readability of the display. Chinese characters generally use Fangsong or Heiti, and other fonts can also be selected according to display requirements.
6.4 Character height
Characters that are too small or too large will be difficult to read. For operations with high requirements for clarity and readability, the viewing angle of a single character height is preferably 20°~22°, and the minimum should not be less than 16. When displaying grouped characters, the viewing angle of the character height should not be greater than 45°. 6.5 Character aspect ratio
For displaying characters with constant spacing, the character aspect ratio (see Figure 3) should be between 1:0.7 and 1:0.9; for the situation where more than 80 characters need to be displayed in a row, the aspect ratio can be reduced to 1:0.5; for displaying characters that are spaced proportionally, the aspect ratio of some characters (such as the uppercase letters M and W) can be close to 1:1. 6.6 Stroke width
The stroke width should be between 1/121/16 of the character height and can be greater than the width of pixels. For positive strokes, it can be wider, and for width
Figure 3 Character height, width and spacing
negative strokes can be narrower.
The stroke width of Chinese characters is 1/16~1/8 of the character height. 6.7 Character size uniformity
No matter where the character is displayed on the screen, the change in the height and width of any character in the character set should not exceed +5% of the character height.
6.8 Character spacing
The character spacing (see Figure 3) should be at least 10% of the character height (or 1 pixel), which can be a fixed spacing or proportional spacing. In some cases, increasing the character spacing (2 pixels!) can improve readability.
6.9 Character spacing
DL/T 575.12—1999
The minimum value of the character width (for balanced spacing, use uppercase N) should be used as the spacing between foreign words. The spacing between Chinese characters should not be less than the width of a stroke, that is, not less than 1/16 to 1/8 of the character height. 6.10 Line spacing
Line spacing refers to the distance between vertically adjacent standard uppercase letters (such as M). The minimum value of line spacing is about 15% of the character height. In practical applications, the line spacing is 50% to 100% of the character height. The line spacing of Chinese characters is also 50% to 100% of the character height. 6.11 Linearity and stability of images
The displayed image should be visually stable and free of geometric deformation. 6.11.1 Linearity
Characters The horizontal displacement of the position relative to the position of the character directly above and below should not exceed 5% of the width of the character frame, and the vertical displacement of the character position relative to the position of the left and right characters should not exceed 5% of the height of the character frame.
The difference in length of a row or column should not exceed 2% of its length. See Figure 4. 6.11.2 Orthogonality
Within the range of linearity requirements, rows and columns should be parallel and orthogonal to each other, which can be expressed as:
0.04 (shorter side/longer side) ≥| (diagonal, /diagonal 2) - 116.11.3 Symbol deformation
The size change of a specific symbol at any position on the display screen should not be greater than 10%, regardless of whether its position is in the image area. It is expressed as follows: 2(hg h)/(ha + h)≤ 0. 1;2(z - w)/(wz + w) ≤ 0. 1 Wherein, "h" is the height of the symbol; "w" is the width of the symbol. Figure 4 Linearity
When all the positions of the characters on the screen are filled with H\ or "M of the same character set, h, is the height of the smallest character, h, is the height of the largest character, w is the width of the smallest character, and w2 is the width of the largest character. 6.11.4 Geometric stability (shake)
The change in the geometric position of the image within one second should be less than or equal to 0.0002 of the viewing distance. This can be expressed as: VX 0. 000 2≥ (H2 + V)0.5
Where: V is the viewing distance; H and V are the maximum horizontal and vertical deviations from the center of the image within the specified measurement time, as shown in Figure 5.
The most sensitive shaking frequency range is 1Hz~3Hz. When the shaking frequency is higher than 25Hz, the image no longer looks shaking, but blurred, that is, the contrast is reduced. 6.12 Brightness
The brightness of the characters or background (whichever is higher) should be greater than 35cd/m; when the ambient illumination is large, this brightness is 100cd/m2 is appropriate.
For reflective displays, such as liquid crystal displays, the incident illumination on the screen should be greater than 35 yuan/RIx, and R in Figure 5 Geometric Stability
is the maximum reflectivity of the screen.
6.13 Brightness Contrast
The character brightness modulation Cm should be greater than or equal to 0.5 (contrast CR≥3:1), preferably greater than 0.75 (contrast Ck≥7:1). Note: Brightness modulation Cm = (Lmx-Lmin)/(Lmax+Imin)) Contrast CR-Lrax/Lmin:
Contrast C = (Lmax Lmin)/Lmm3
Lmax…the brighter one of the background or the characters; L.in the smaller one of the background or the characters DL/T575.12-1999
The above brightness includes the effect from the ambient lighting 6.14 Image polarity
The positive polarity of the image refers to the dark characters on the bright background, and the negative polarity refers to the bright characters on the dark background. As long as the images of these two polarities meet the requirements specified in Articles 6.12 and 6.13, they are both usable. The edges of the positive polarity image are sharper, which is easy to meet the brightness balance requirements, and it also reduces the distracting light reflection effect, but in order to avoid flicker, this type of display needs to have a simpler refresh rate. Flicker is less common in negative polarity images. For people with poor eyesight, the clarity is better and the characters look larger than they actually are. 6.15 Brightness uniformity
All displays that need the same brightness should have the same brightness. Therefore, the brightness change from the center to the edge of the display's effective screen should not exceed 50% of the center brightness.
6.16 Brightness coding
Use different brightness levels to encode display information. Since the human visual system is not sensitive to the absolute value of brightness and needs to consider the impact of ambient lighting conditions on it, it is only appropriate to use brightness differences as coding to a limited extent. 6.17 Flashing Codes
Flashing can be used to draw attention to important information or dangerous situations. No more than two different flashing rates should be used. The difference between the two flashing rates should be at least 2Hz. The slow flashing rate should not be less than 0.8Hz, and the fast flashing rate should not be more than 5Hz. The time when the image is in "light" should be greater than or equal to the time when it is in "dark". It is best if the light and dark time are equal. 6.18 Color Coding
For coding purposes, colors can be used and attention should be paid to color contrast. For text, thin lines, or high-resolution information, avoid using pure blue on a black background; if pure red and pure blue (or less pure red and green, or blue and green) are displayed at the same time, it may cause color stereoscopic vision (three-dimensional effect) on a black background, so it should also be avoided.
If color coding is used to make the displayed information recognizable or eye-catching, the minimum color difference △ (CIE1u*) between each pair of colors in this set should be 40. In this way, at least 7 to 10 colors can be used simultaneously. Increasing the ambient illumination will reduce the purity of the color. This will reduce the recognizability of the color.
In order to have sufficient clarity, the color difference △E (CIEYuv) between the colored symbol and its colored background should be at least 100. 6.19 Flickering
In actual use, more than 90% of the user group should feel that the display screen is "flicker-free". Flickering displays are annoying, and screen flicker should be eliminated as much as possible. 6.20 Controllers
Frequently used controllers should be easily visible and accessible to VDT users from their normal working positions. Controllers with covers should generally not be accidentally activated. Their functions and current settings should be clearly indicated. Color (RT) displays should have adjustments for brightness, contrast, focus and color balance, which can be achieved through separate controllers or according to software instructions. LCD displays do not have any controllers because they have a fixed contrast whose width depends on the ambient illumination.
7 Input devices
For the general principles for the classification and selection of input devices, see DL/T575.9. This chapter only makes necessary explanations on the characteristics of VIDT workstations.
7.1 Keyboard
The keyboard is still one of the indispensable and most commonly used input devices of VIDT workstations. Commercialized universal keyboards generally take ergonomic principles into full consideration. However, it should be noted when applying: 1364
DL/T575.12--1999
a) The height of the keyboard and its supporting table should be coordinated with the height of the seat and meet the requirements of leg and knee space so that the user can maintain a comfortable position for the body and arms;
b) The placement of the keyboard should be stable to ensure that normal keystroke operation will not cause the keyboard to slide or shake; c) The keyboard should be allowed to be repositioned on the table. The keyboard and the display should generally be placed at the same depth of vision, with a change of about (4 screens of brightness:
d) There should be tactile or auditory feedback, or both, accompanying the keystrokes during keyboard operation. If there is only one type, tactile feedback is best. If auxiliary auditory feedback is used, all keys should make a sound when they are moved to a certain distance, and the volume can be adjusted until it is turned off. 7.2 Non-keyboard input devices
Various non-keyboard input devices, such as mouse, joystick, trackball, graphic tablet, input pen, touch screen, voice input, etc., are constantly changing with the development of technology. However, they must all follow the following ergonomic principles: a) Suitable for the task and working environment; b) Easy to operate, adapt to the physiological and psychological characteristics of people, and easy to learn; c) Easy to operate, timely respond and clear feedback; d) Save effort and time.
These principles are specifically applied to each input device, and some respective requirements should also be proposed, as shown below. 7.2.1 Touch screen
a) The touch target should be below shoulder height, and its sensitive area should be at least equal to the distal joint width of the index finger of the 95th percentile man, and there should be at least 5mm of insensitive area around it. If parallax occurs and affects the operation effect, the sensitive area needs to be slightly expanded. b) The size and contrast of the characters or symbols on the screen should comply with the relevant provisions of Chapter 6. c) The screen should be treated to eliminate static electricity. d) To avoid accidental activation, there should be a delay of 500ms to 750ms between repeated displays. e) In the operation of dragging the screen, the object or cursor should move in real time and on the spot with the finger or light pen. 7.2.2 Graphic Input Board
a) If the input board is fixedly installed on the workbench, its height, depth and inclination should allow the user to maintain a suitable working postureb) The surface of the input board should be flat and smooth, and the reflection or glare on its surface should not hinder the operation and affect the visual effectc) The writing force required by the input board should not be greater than 1.0Nd) From the design viewing distance, the graphic symbols on the input board should be recognizable, and the viewing angle of the characters or symbols should be at least 16°, preferably 20\; its brightness contrast should be at least 3:1; its color should be easy to distinguish. e) The grouping of various functions on the input board should be easy to distinguish. 7.2.3 Input pen
a) The length of the cylindrical pen holder is 120mm~180mm, the diameter is 7mm~20mm, and the weight is 10g~25gb) It is easy to hold and not easy to slip.
c) During continuous input, the force applied by the pen on the graphic input board or screen should not be greater than 0.8N. d) The contact surface diameter of the option button on the pen holder should be greater than 5mm, and the required release force should be between 0.3N~~0.8N8 Principles of human-computer dialogue
The existing human-computer dialogue methods include "menu", "form filling", "command language" and "direct manipulation". With the development of technology, new dialogue methods will emerge. Regardless of the human-computer dialogue method, it should be able to meet the following ergonomic requirements. 8.1 Adaptability
a) The dialogue should adapt to the physiological and psychological characteristics of the user, including: 1) short-term memory limit;
2) attention span,
3) language and cultural background;
DL/T 575.12-1999
4) learning ability, work level or experience in using this system; 5) content of interest, etc.
b) The dialogue should adapt to the individual needs of different users, for example: 1) Allow users to choose the expression format or modify the interface software according to their personal preferences or the complexity of the information to be processed; 2) Provide various guidance methods to help users who are not familiar with this system learn to use it; 3) For users who use it frequently and are very familiar with it, reduce the number of dialogues, increase the pace of dialogues, and try to shorten the feedback time and increase the display rate;
c) The selection of dialogue methods should be based on the resources and technical conditions already available. 8.2 Effectiveness
Dialogue should help users complete tasks effectively and economically, for example: a) Provide users with all task-related information while omitting any dialogue that can be omitted; b) When some data needs to be changed during the execution of a task, the original data should be retained and have a restore function. 8.3 Self-narrative
a) Each step of the dialogue can be fed back by the system itself so that the user can understand it immediately, or it can be explained at the user's request. b) Changes in the state of the dialogue system and any task-related information can be notified to the user in a timely manner. C) The feedback information prompted should be objective, clear, easy to understand, constructive, and not contain any praise or criticism. 8.4 Controllability
a) The following aspects of the dialogue can be placed under the control of the user: 1) The rate and direction of interaction;
2) Interruption and resumption of the dialogue;
3) The expression method (format and type) of input/output. b) Users can choose the input/output device according to their needs. 8.5 Consistency
a) The behavior and performance of dialogues within the system should be consistent (e.g., prompts for system status always appear on the same line, and the same key is always used to terminate a dialogue).
b) Operations that change status should always be consistent (e.g., "Help\" always uses the F1 key).
c) In similar situations, a consistent sequence of operations and consistent commands must be used.
d) Feedback information or explanations should be expressed in consistent terms.
e) Use the same terms for "prompt", "menu", and "help".
8.6 Fault tolerance and error prevention capabilities
a) Set up a proofreading function so that even if there are obvious errors in the input, the expected results can be obtained without the user taking corrective measures or only taking very few corrective measures. For example, when the user only types a left bracket, a right bracket can be automatically generated and the cursor can be placed in the middle to facilitate the typing of the content in the bracket.
b) Prompt and prevent the user from inputting when an undefined state or system failure may be caused. c) Simplify the operating instructions and operating procedures as much as possible to reduce input errors. d) Reduce keystroke input and use menus, pointing input, etc. instead. 9 Workbenches and chairs
When applying ergonomic principles to the design and selection of workbenches and chairs, many interacting factors (e.g., anthropometric data, job requirements, possible working postures, VDT hardware, etc.) need to be considered and weighed. This should be fully considered during the planning and design stage of the workstation.
For the principles and requirements for the design and layout of workbenches, see DL/T575.8. For the anthropometric data of the sitting posture, see Appendix B of DL/T575.8.
9.1 General principles
DL/T 575. 12--1999
a) Consider the VDT, workbench, chair and work environment as an integrated system. b) Develop recommendations based on anthropometric data and existing work practices. c) The recommended values are specified for people using the VDT in a sitting posture to accommodate the 5th percentile female body size to the 95th percentile male body size.
d) The ergonomic requirements listed are generally not related to the manufacturing process technology of tables and chairs. 9.2 Knee space under the workbench surfacewww.bzxz.net
If the height of the workbench surface is not adjustable, the knee space is determined according to the 95th percentile size of men, as shown in Figure 6. If the height of the workbench surface is adjustable, the adjustment range of the knee height is 520mm to 640mm. 9.3 Keyboard and display support surface
9.3.1 Keyboard support surface
The height of the keyboard support surface should allow the operator in a seated position to assume a forearm position between (70+Y/2)° and (90+Y/2)°, as shown in Figure 7. Where Y is the recline angle between the seat back and the vertical plane. The angle between the upper arm and the forearm should preferably be between 70° and 135°.
If the keyboard support surface height is not adjustable, it should be made to accommodate larger persons, and a footrest or other accessories should be provided for smaller VDT users. If a lower fixed table is used, larger persons can lower the seat surface, sit with their legs extended forward, and operate the keyboard with a forearm angle exceeding 90°. The height of the keyboard support surface is 660mm~750mm (i.e. the height of the keyboard working surface is 680mm~~770mm) 9.3.2 Support surface of the display
The height of the display support surface should make the entire display screen located within the observation area between 0° and 60° below the user's eye level, and the knee space under the workbench surface should comply with the provisions of Article 9.2. As shown in Figure 8. (70+Y /2)
-(90+Y /2)
-135°
Figure 7 Height of the keyboard support surface
9.3.3 Unified support of keyboard and display
Figure 8 Height of the display support surface
For a single workbench surface, the main factor determining the height of the surface is the height of the keyboard working surface. 9.4 Width and Depth of Workbench Surface
The width and depth of the workbench surface depend on the VDT hardware, the work situation, hard copies (such as documents, materials), and the knee space under the surface (see 9.2). A work analysis must be conducted to determine the space requirements. The workbench surface area should be sufficient to accommodate the objects required to complete the work, and should also consider the coordination with other workbenches and chairs in the room. 9.5 Chair
The chair is an integral part of the workstation. The chair structure affects the user's comfort and freedom of movement. A well-designed chair should be suitable for the person's working posture, internal circulation, and the amount of pressure on the spine. The design and selection of the chair need to consider the human body measurement, work habits, and the adjustability, flexibility and safety of the chair components and mechanisms. 9.5.1 Seat height
Foot support - shoe + footrest
Figure 9 Adjustment range of seat height
The seat height should allow the feet to be placed securely on the support surface to support the calves and stabilize the sitting posture. Therefore, the seat height is determined by the following factors: the chest height and heel height of the 5th percentile female to 95th percentile male, the angle of the calf supported by the seat, and the height and type of foot support (such as footrest). The minimum adjustment range of the seat height is 360mm to 480mm. As shown in Figure 9.
Seat depth
The maximum depth of the seat should allow the lumbar area to rest on the seat back and avoid pressure on the back of the calf. Due to the large variation in hip length between tall men and short women, the seat depth suitable for short women may not provide suitable support for tall men. Therefore, a compromise should be adopted to make the seat depth acceptable to the majority of the user group. According to general practice, the seat depth can be 360mm~390mm (recommended value 380mm). For seats with a depth exceeding 375mm, it is recommended to design the front edge of the seat into a convex arc structure (such as a "waterfall-like profile") so that it is located just below the inner side of the user's knees and thighs, allowing the inner side of the knees to relax, see Figure 10. 9.5.3 Seat width
The minimum width of the seat should be the width of the two thighs of a large person sitting (approximately equal to the sitting hip width), see Figure 11. The width between the edges of the seat (not the edge of the fabric) is 370mm~420mm (recommended value 400mm). Seat depth
Seat width
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Figure 10 Seat depth
9.5.4 Seat surface inclination
Figure 11 Seat width
For those seats that require users to place their feet flat on the ground or support their feet The seat surface inclination design of the seat that can be adjusted by supporting objects. It should be ensured that the angle between the thigh and the calf is between 60° and 100° when the calf is perpendicular to the ground, see Figure 12. Those seats that provide calf support may make the angle between the thigh and the thigh as large as 140°. The seat surface inclination should give priority to the sitting posture that supports the body weight on the thighs and buttocks, and the waist leans on the seat back.
If the seat surface inclination is fixed, it should be 0° to 10°; if it is adjustable, the adjustment range should be within 0° to 10°. The seat can have a seat surface that tilts forward or backward, but the seat surface that tilts forward is only used for special operations, and it should be ensured that the seat surface cloth provides sufficient friction to avoid slipping.
9.5.5 Angle between the seat back and the seat surface The angle between the seat back and the seat surface should allow the user to take Take a working posture with the angle between the torso and thigh not less than 90°: otherwise, sitting for a long time will cause fatigue and discomfort. A chair with a forward-leaning seat should not force the upper body to be in a forward-leaning state. For a chair with a fixed backrest, the angle α between the backrest and the seat surface should be in the range of 90° to 105°, see Figure 13. 9.5.6 Backrest
9.5.6.1 Backrest height
The chair should be provided with a backrest, and its height depends on the person's posture, working conditions, personal preferences and the function of the chair. When working in a sitting position, the waist and spine are most prone to fatigue. The structure and size of the backrest should provide sufficient support for the waist to make the spine close to the normal natural curvature state. Backrests with an angle greater than 105° should have sufficient The height should be high enough to properly support the trunk, head and neck of the person. 100
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Figure 12 Seat chassis angle
9.5.6.2 Lumbar support
Figure 13 Between backrest and seat surface
The seat should provide support in the lumbar area of the person through the lumbar support, the center of which should be located between the third lumbar vertebra (L3) and the fifth lumbar vertebra (L). Its shape should be adapted to the lordosis of the spine in the lumbar area (i.e., a contoured lumbar support should be used) to help reduce fatigue and deformation of the back and spine, enhance the support force of the spine, and relax the muscles, as shown in Figure 14. The height of the lumbar support in the vertical direction should be 200mm~300mm (recommended value 250mm); the width in the horizontal direction should be 320mm~340mm (recommended value 330mm). It should be convex in the vertical direction and concave in the horizontal direction. The vertical height of the lumbar support center can be fixed or adjustable, and the adjustment range is usually between 165mm and 210mm above the seat reference point (the center point of the seat surface, if there is a seat cushion, the center point after being compressed with a 45kg load). 9.5.6.3 Seat back width
The seat back width at the waist should be at least 320 mm. 9.5.7 Armrests
Figure 14 Lumbar support
The horizontal distance between the inner edges of the two armrests should be 460 mm to 500 mm. The armrests should not hinder the user from performing work or restrict their working posture.
9.6 Seat casters
For most workstation layouts, seats need to be equipped with casters because casters allow users to move around the workstation without leaving the seat. Casters should be selected according to the type of floor. Casters with a very low friction coefficient should not be used for hard floors. 9.7 Swivel chairs
Swivel chairs with swivel seats allow users to easily and safely change body directions without twisting their waists. 9.8 Footrests
When the height adjustment range of the seat or workbench surface does not allow the user's feet to be placed flat on the ground, a footrest of appropriate height should be provided.
9.9 Auxiliary tools
VDT users can choose a variety of auxiliary tools according to their needs and preferences to help improve the comfort of workstation operations. Auxiliary tools include (but are not limited to): a) hand pads: supports for hands and forearms on the keyboard; b) folders: used for data input and text processing; c) task lighting: provides more appropriate illumination for specific areas; d) universal keyboard tray: provides convenience for height adjustment (and other arrangements) for separate keyboards. 1369
DL/T575.12--1999
Appendix A
(Suggestive Appendix)
Main References
［1IANSI/HFS100--1988 Ergonomics of Visual Display Terminal (VDT) Workstations［2］ISO9241 Ergonomics Requirements for Visual Display Terminals (VDT) for Office Work Part 1 (1997): General
Part 3 (1992): Requirements for Visual Displays Part 4 (1992): Requirements for Keyboards
Part 5 (1998): Requirements for Workstation Layout and Human Posture Part 6 (DIS, 1998): Environmental Environmental requirements Part 8 (1997): Display color requirements Part 9 (DIS, 1998): Requirements for non-keyboard input devices Part 10 (DIS: 1996): Dialogue principles [3] ISO DIS 13406 (1996) Ergonomic requirements for visual displays based on flat screens Part 1: General
Part 2: Requirements for flat screen displays
[4] GB/10000—88 Chinese adult body dimensions [5] GB/T 14774—93 Work seats - General ergonomic requirements [6] GB/T 3326—1997 Main dimensions of furniture tables, chairs and stools [7] GB 3976--83 Functional dimensions of school desks and chairs 1370
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