In industrial design, preferred numbers (also called preferred values ​​ or preferred series ) are standard guidelines for choosing the right product dimensions in a single set specified limits. The product developer must choose many lengths, distances, diameters, volumes, and other number of characteristics. While all of these options are limited by consideration of functionality, usability, compatibility, security or cost, there is usually still considerable looseness in the right choice for many dimensions.
The selected number has two objectives:
- Using it increases the likelihood of compatibility between objects designed at different times by different people. In other words, this is one of many tactics in standardization, whether in a company or in an industry, and is usually desirable in an industrial context (unless the purpose is a lock-in vendor or outdated plan)
- They are chosen in such a way that when a product is produced in any size, it will end up with the same distance on a logarithmic scale. Therefore they help to minimize the number of different sizes that need to be manufactured or stored in stock.
The selected number represents a simple number preference (such as 1, 2, and 5) multiplied by the appropriate power, usually 10.
Video Preferred number
Jumlah renard
In 1870, Charles Renard proposed a preferred set of numbers. The system was adopted in 1952 as an international standard ISO 3. The Renard system divides the intervals from 1 to 10 into 5, 10, 20, or 40 steps, each leading to the R5, R10, R20 and R40 scales. Factors between two consecutive numbers in the Renard series are almost constant (before rounding), ie 5, 10, 20, or 40 roots of 10 (about 1.58, 1.26, 1.12, and 1.06, respectively), leading to a geometric sequence. In this way, the maximum relative error is minimized if the random number is replaced with the nearest Renard number multiplied by the appropriate 10 forces.
Maps Preferred number
1-2-5 series
In the R5 series app gives too fine grading, the 1-2-5 series is sometimes used as a rough alternative. Effectively R3 series is rounded to one significant digit:
... 0,1 0,2 0,5 1 2 5 10 20 50 100 200 500 1000...
This series covers a decade (ratio 1:10) in three steps. The adjacent values ​​differ by factor 2 or 2.5. Unlike the Renard series, the 1-2-5 series has not been officially adopted as an international standard. However, the Renard R10 series can be used to extend the 1-2-5 series for better graduation.
This series is used to determine the scale for the graph and for the instrument shown in two dimensional form with graticule, like oscilloscope.
The most modern currency denominations, especially the euro and the British pound, follow the 1-2-5 series. The United States and Canada follow the 1 to 5, 10, 25, 50, 100 (cent), $ 1, $ 2, $ 5, $ 10, $ 20, $ 50, $ 100, , ¼-½-1 (... 0.1 0.25 0.5 1 2.5 5 10...) is also used by currencies originating from Dutch guilders previously (Aruban florin, Netherlands Antilles guilder, Suriname dollar ), some Middle Eastern currencies (Iraqi and Jordanian dinars, Lebanese pound, Syrian pound), and Seychelles rupees. However, new records are being introduced in Lebanon and Syria because inflation follows the 1-2-5 series standards instead.
Convenient numbers
In the 1970s, the National Bureau of Standards (NBS) defined a set of easy figures to facilitate metrics in the United States. The system of metric values ​​is described as reversed series 1-2-5, with preferences assigned to numbers of 5, 2, and 1 multiples (plus their strength of 10), excluding linear dimensions above 100 mm.
E-series
E-series is another system of preferred numbers. It consists of series E3, E6, E12, E24, E48, E96 and E192. Based on several existing manufacturing conventions, the International Electrotechnical Commission (IEC) began work on new international standards in 1948. The first version of IEC 63 (renamed IEC 60063 in 2007) was released in 1952.
It works similarly to the Renard series, except that it divides the intervals from 1 to 10 into 3, 6, 12, 24, 48, 96 or 192 steps. This subdivision ensures that when some arbitrary value is replaced by the closest desired number, the relative maximum error will be in the order of 40%, 20%, 10%, 5%, etc.
The use of E-series is largely limited to electronic components such as resistors, capacitors, inductors and Zener diodes. Dimensions produced generally for other types of electrical components are selected from the Renard series instead or defined in relevant product standards (eg cables).
Paper documents, envelopes and drawing pen
The standard metric paper size uses the square root of two (? 2 ) as a factor between the dimensions of neighbors rounded to the nearest mm (Lichtenberg series, ISO 216). A4 sheet for example has a very close aspect ratio to ? 2 and an area very close to 1/16 square meter. A5 is almost exactly half A4, and has the same aspect ratio. Factor ? 2 also appears between standard pen thicknesses for technical drawings (0.13, 0.18, 0.25, 0.35, 0.50, 0.70, 1.00 , 1.40, and 2.00 mm). In this way, the correct pen size is available to continue the enlarged image to a different standard paper size.
Computer engineering
When the computer component dimension, power of two is often used as the preferred number:
1 2 4 8 16 32 64 128 256 512 1024...
Where needed a better rating, the desired additional amount is obtained by multiplying the strength of the two with a small odd integer:
1 2 4 8 16 32 64 128 256 512 1024... (ÃÆ'â € "3) 3 6 12 24 48 96 192 384 768 1536... (ÃÆ'â € "5) 5 10 20 40 80 160 320 640 1280... (ÃÆ'â € "7) 7 14 28 56 112 224 448 896 1792...
In computer graphics, the width and height of the raster image are preferred for multiples of 16, as many compression algorithms (JPEG, MPEG) divide the image color into the square block of that size. The black-and-white JPEG image is divided into 8 Ã- 8 blocks. Screen resolution often follows the same principle. The aspect ratio of choice also has an important influence here, for example, 2: 1, 3: 2, 4: 3, 5: 3, 5: 4, 8: 5, 16: 9.
Retail packaging
In some countries, consumer protection laws limit the number of different packaging sizes to which a particular product can be sold, to make it easier for consumers to compare prices.
An example of such regulation is the EU directive on pre-packed liquid volume (75/106/EEC). This limits the list of allowed wine bottle sizes to 0.1, 0.25 (1/4), 0.375 (3/8), 0.5 (1/2), 0.75 (3/4), 1, 1 , 5, 2, 3, and 5 liter. A similar list is available for some other product types. They vary and often deviate significantly from a series of geometries to accommodate traditional sizes whenever possible. The size of adjacent packages in this list is usually different from the 2/3 or 3/4 factors, in some cases even 1/2, 4/5, or some other ratio of two small integers.
Photography
In photography, the shutter speed, lighting, and film speed generally follow the 2:
The size of the aperture controls how much light goes into the camera. This is measured in f-stop: f /2, f /2.8, f /4 , etc. Full f-stops are square roots of 2 apart. Digital Cameras often divide this into three parts, so each f-stop is the sixth root of 2, rounded into two significant digits: 1.0, 1.1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.5, 2.8, 3.2, 3.5, 4.0, etc.
The film speed is the size of the film's sensitivity to light. This is expressed as an ISO value such as "ISO 100". The measured film speed is rounded to the nearest choice number of the modified Renard series including 100, 125, 160, 200, 250, 320, 400, 500, 640, 800... This is the same as R10? Renard spherical series, except for the use of 6.4 instead of 6.3, and for having a more aggressive rounding under ISO 16. Movies marketed for amateurs, however, use a limited series including only two-strength multiples of ISO 100: 25, 50, 100, 200, 400, 800, 1600 and 3200. Some low-end cameras can only read these values ​​from DX-coded film cartridges because they do not have the additional electrical contacts required to read the full series. Some digital cameras extend this binary series to values ​​like 12800, 25600, etc. Instead of the modified Renard value 12500, 25000, etc.
Source of the article : Wikipedia
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