原子筆又叫圓珠筆，係筆嘅一種，係相當近代嘅發明。原子筆嘅「原子」就係嗰啲𠹳澾澾，黐𥹉𥹉嘅「墨」，筆嘴最尖係一粒直徑 0.7 - 1.2 mm 嘅金屬珠，啱啱卡住響支收窄嘅管嘅尾尾，卡得唔係太實而可以畀粒珠自由噉轉，當識轉嘅金屬珠掂倒紙嘅表面嗰陣，氹氹轉嘅珠令喺支窄嘅管裏面嘅墨留低喺紙上面，一落倒紙嘅墨差唔多立即乾。今時今日，又平、又靠得住、重唔使點理嘅原子筆，已經取代咗墨水筆，變成好多人日日用嚟寫嘢嘅筆。
製造經濟可靠嘅原子筆，係嚟自實驗、現代化學、同埋20世紀精密製造科技嘅結合。好多國際專利見證咗一啲失敗嘅嘗試，想令原子筆可以賺錢同廣泛噉用。甚至有人認為一個出自 Galileo Galilei 喺十七世紀嘅設計，其實就係原子筆嚟。
第一個原子筆嘅專利係喺1888年10月30號發行畀 John J Loud 。嗰枝筆有一粒旋轉嘅小鋼珠，由一個插座固定喺適當嘅位置。呢枝筆用嚟寫字母就太粗，但可以寫喺粗糙嘅表面（尤其係皮革），佢始終冇喺市場上發售。
喺 1900 至 1940 年之間，好多人都好想改進寫字嘅工具，尤其係改進鋼筆或者搵一啲代替嘅工具。 Slavoljub Eduard Penkala 喺 1907年發明咗固體墨水嘅鋼筆，德國一位叫 鮑姆掏 (Baum) 嘅發明家喺1910年出咗原子筆嘅專利，同埋另一種原子筆設備嘅專利就喺1916年俾 Van Vechten Riesburg 得到。 喺呢啲發明度，墨水係放喺幼管入面，而管嘅最尾就有一粒細珠阻住，粒細珠會保持喺個位度，唔會滑咗入去幼管入面或者跌咗出嚟。 The ink clung to the ball, which spun as the pen was drawn across the paper. These proto-ballpoints did not deliver the ink evenly. If the ball socket was too tight, the ink did not reach the paper. If it was too loose, ink flowed past the tip, leaking or making smears. Many inventors applied their minds and skills to remedying these faults, but without commercial success. (http://www.herend.com/herald/012/eng/eletmod.htm)
László Bíró, a newspaper editor, was frustrated by the amount of time that he wasted in filling up fountain pens and cleaning up smudged pages, and the sharp tip of his fountain pen often tore his pages of newsprint. Bíró had noticed that the type of ink used in newspaper printing dried quickly, leaving the paper dry and smudge free. He decided to create a pen using the same type of ink. Since, when tried, this viscous ink would not flow into a regular fountain pen nib, Bíró, with the help of his brother George, a chemist, began to work on designing new types of pens. Bíró fitted this pen with a tiny ball in its tip that was free to turn in a socket. As the pen moved along the paper, the ball rotated, picking up ink from the ink cartridge and leaving it on the paper. Bíró filed a British patent on 15 June, 1938.
Earlier pens leaked or clogged due to improper viscosity of the ink and depended on gravity to deliver the ink to the ball. Depending on gravity caused difficulties with the flow and required that the pen be held nearly vertically. The Biro pen both pressurized the ink column and used capillary action for ink delivery, solving the flow problems.
In 1940 the Bíró brothers and a friend, Juan Jorge Meyne, moved to Argentina fleeing Nazi Germany and on June 10, filed another patent, and formed Bíró Pens of Argentina.
The pen was sold in Argentina under the Birome brand (acronym of Biro and Meyne), which is how ballpoint pens are still known in that country. Laszlo was known in Argentina as Ladislao José Bíró. This new design was licensed by the British, who produced ball point pens for RAF aircrew, who found they worked much better than fountain pens at high altitude.
Eversharp, a maker of mechanical pencils teamed up with Eberhard-Faber in May 1945 to license the design for sales in the United States. At about the same time a U.S. businessman saw a Biro pen in a store in Buenos Aires. He purchased several samples and returned to the U.S. to found the Reynolds International Pen Company, producing the Biro design without license as the Reynolds Rocket. He managed to beat Eversharp to market in late 1945; the first ballpoint pens went on sale at Gimbels department store in New York City on 29 October 1945 for US$12.50 each (about US$130 of today's money). This pen was widely known as the rocket in the U.S. into the late 1950s.
Similar pens went on sale before the end of the year in England, and by the next year in most of Europe. Cheap disposable instruments were produced by the BIC Corporation with "Bic" as the tradename; as with 'Hoover' and 'Xerox', the tradename has subsequently passed into general use. With BIC's expanding product range, the original Bic pen design is now termed the Bic Cristal.
一次性嘅筆主要係由塑膠整嘅，啲墨用嗮就成枝筆唔用得，可更換筆芯嘅筆係金屬或塑膠整，但佢質量同成本會比一次性嘅筆高。The refill replaces the entire internal ink reservoir and ball point unit rather than actually refilling it with ink, as it takes special high-speed centrifugation to properly fill a ball point resevoir with the viscous ink.
The simplest types of ball point pens have a cap to cover the tip when the pen is not in use, while others have a mechanism for retracting the tip. This mechanism is usually controlled by a button at the top and powered by a spring within the pen apparatus, but other possibilities include a pair of buttons, a screw, or a slide.
- Rollerball pens, which combine the ballpoint design with the use of liquid ink and flow systems from fountain pens;
- "Space Pens", developed by Fisher in the United States, which combine a more viscous than normal ballpoint pen ink with a gas pressurized piston which forces the ink toward the point. This design allows the pen to write even upside down or in zero gravity environments.
The International Organization for Standardization has published standards for ball point and roller ball pens:
- ISO 12756:1998 Drawing and writing instruments -- Ball point pens and roller ball pens -- Vocabulary 
- ISO 12757-1:1998 Ball point pens and refills -- Part 1: General use 
- ISO 12757-2:1998 Ball point pens and refills -- Part 2: Documentary use (DOC) 
- ISO 14145-1:1998 Roller ball pens and refills -- Part 1: General use 
- ISO 14145-2:1998 Roller ball pens and refills -- Part 2: Documentary use (DOC) 
原子筆喺現代文化之中無處不在。While other forms of pen are available, ballpoint pens are certainly the most common and almost every household is likely to have several. The fact that they are so cheaply available (costing from just a few cents/pence to produce) and so convenient to use means they are often to be found on desks and also in pockets, handbags, purses, bags and in cars — almost anywhere where one could conceivably need to use a pen. Ballpoint pens are often provided free by businesses as a form of advertising — printed with a company's name, a ballpoint pen is a relatively low cost advertisement that is highly effective (customers will use, and therefore see, a pen on a daily basis). Businesses and charities may also include ballpoint pens in direct mail mailings in order to increase a customer's interest in the mailing.
In recent years, the ballpoint pen has become a popular art medium, as demonstrated by such websites as biro-art.com. Many people also create art on themselves with the pens; this is sometimes known as a ballpoint tattoo. Due to this, and to its wide-spread use by schoolchildren, all ballpoint ink formulas are non-toxic, and the manufacturing and content of the ink is regulated in most countries.
Ballpoint pens have three characteristics that distinguish them from rollerball systems. First, the ink flow increases with pressure. A rollerball will typically lay down its line without pressure.
Second, they write with the greatest ink flow when perpendicular to the paper, but as the angle is increased the line width gradually decreases; at some angle, when the edge of the ball socket brushes against the surface of the paper, the line width is reduced to zero and the pen ceases to write. By contrast, a rollerball pen has a thin line when perpendicular to the paper, but the line width increases suddenly as the angle is increased and a blob forms between the tip of the ball and the edge of the socket.
Third, a ballpoint pen's ink is typically not as bright on paper as its liquid or gel ink counterparts.
These characteristics have consequences for the grip with which the pen is held. First, one tends to bear down on a ballpoint to get a stronger line, and this increases tension in the hand. One way of getting a stronger line, comparable in intensity to a rollerball line, is to use a broad line ballpoint, with a 1.2mm diameter, or greater, ball size. Most ballpoints have a thin or medium ball.
Second, one has to hold the pen sufficiently vertically for it to roll across the paper and not to scratch. Most people nowadays are so accustomed to writing nearly perpendicularly that they do not realize that there are other ways to hold a pen.
There are two kinds of pens that can write at greater angles than ballpoint pens: fountain pens and felt-tipped pens. Both of these types of pen also write with less pressure and therefore with less tension in the hand.
- The Al Faisalia skyscraper in Riyadh, Saudi Arabia, takes the shape of a ballpoint pen.
- The ballpoint pen drawing 'Inhuman Pyramid' is two meters tall, one and a half meters wide, used up six ballpoint pens and took seven months to complete.
- On average, 100 people choke to death on ballpoint pens every year.
- Scribble circles on cardboard found covering notepads. Normal 80g/sq.m paper doesn't seem to restore ink flow as quickly.
- 喺玻璃表面上畫幾個圓圈(the closest window works well) 
- Heat the ball point for a few seconds over a small flame (eg. cig. lighter) 
- Insert inside the opening of your ink cartridge a piece of mechanical pencil graphite (best to be 0.7mm) 
- GB Patent No. 15630，1888年10月30號
- Biro Art - Doodles with a ball point pen.
- Rare photo-realist drawings done in ball-point (birodrawing.co.uk)
- A history of the ballpoint pen.
- Dennis Carlisle, Ball point pen artist.
- Information about pens of various types; pen help for beginners.
- Eric Bostrom's gallery (has come up with some blending techniques, as well)
- Did Biros really revolutionise writing? - BBC News - October 24, 2006
- Writing Instrument Manufacturers Association
- Duct Tape Ballpoint Pen