Name: 噴墨印表機的微滴工程與形成原理大公開！ (The Engineering of Droplets and their Formation in a Commercial Inkjet Printer)
Uploaded: 2026-03-29T07:14:00.000Z
Duration: 5 min 52 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

These toys dazzle with a color, and the patterns formed.

這些玩具以顏色和形成的圖案令人驚豔。

To create their beautiful displays, all rely on the formation of droplets.

為了創造出牠們美麗的展示，全都是靠液滴的形成。

Droplets, especially controlling the size of droplets, is of enormous technological importance: the mist from an asthma inhaler, the paint sprayed on cars, or the fuel entering the cylinder of a car's engine.

液滴，尤其是控制液滴的大小，具有巨大的技術重要性：像是氣喘吸入器的噴霧、噴在汽車上的油漆，或是汽車引擎汽缸裡進入的燃料。

To understand how engineers control drop size, let's start with this toy, which shows the essentials of drop formation.

為了了解工程師如何控制液滴的大小，我們就從這個玩具開始，它展示了液滴形成的基本原理。

In it, a narrow stream of liquid called a jet flows from the opening, and

在裡面，一股狹窄的液體流，稱為 jet，從開口流出，

it becomes circular as it flows toward the bottom of the toy.

並且在流向玩具底部時變成圓形的。

As you can see here, the droplets are typically the same size.

就像你們在這裡看到的，這些液滴通常大小都一樣。

This toy motivates the key scientific question: why does a droplet form at all?

這個玩具激發了一個關鍵的科學問題：液滴到底為什麼會形成？

Why doesn't a jet go on forever without breaking up?

為什麼 jet 不會永遠不斷地流動而不破裂？

To answer that question, I've put a small hole in this cup, and

為了回答這個問題，我在這個杯子上打了一個小洞，

we'll fill it with a 50/50 mixture by volume of water and glycerol dyed green.

我們要將它裝滿體積比例為 50/50 的水和綠色染料甘油。

Glycerol is highly viscous, meaning informally that it's a thick liquid, so it will slow the flow and the formation of drops.

甘油的黏滯性很高，簡單來說就是一種濃稠的液體，所以它會減緩流動和液滴的形成。

你們可以看到一個平滑的 jet 流出，

as it travels further from the cup, the stream gets fuzzy, which you can see better in close-up.

但當它從杯子流得更遠時，水流變得模糊，你們可以從特寫鏡頭看得更清楚。

我們來放慢速度看看會發生什麼事。

You see the smooth jet at the top, then as the stream descends, droplets forming the fuzziness earlier.

你們可以看到頂部是平滑的 jet，然後隨著水流下降，液滴會更早形成模糊的樣子。

Notice that just as the liquid exits, it forms a uniform cylinder, but

請注意，液體一出來時，它會形成一個均勻的圓柱體，

as it descends, the cylinder's sides wobble, which increases in intensity so that bulges form and disappear until this instability, this wobble, slices the jet into drops.

但隨著它下降，圓柱體的側面會開始晃動，這種晃動越來越劇烈，直到凸起形成又消失，直到這種不穩定性，這種晃動，將 jet 切割成液滴。

The instability is caused by a liquid's tendency to minimize its surface area, a tendency toward the most thermodynamically stable state.

這種不穩定性是由液體趨向於最小化其表面積的傾向所引起的，這是一種趨向於最熱力學穩定狀態的傾向。

For this jetting liquid, that would be a sphere rather than a cylinder.

對於這種噴射的液體來說，那就是一個球體而不是圓柱體。

The surface area-to-volume ratio of a sphere is double that of an optimized cylinder with the same radius.

球體的表面積與體積比，是相同半徑的優化圓柱體的兩倍。

I said it was uniform, but you can now see that the wobbling begins soon after exiting.

我說過它很均勻，但你現在可以看到，在流出後不久，晃動就開始了。

The flickering is that wobble, seen better if I zoom in and add guidelines.

這種閃爍就是那種晃動，如果我放大並加上輔助線，會看得更清楚。

Why, though, doesn't the cylindrical jet immediately become a sphere?

但為什麼圓柱狀的 jet 不會立刻變成球體呢？

That's because the minimization of the surface area competes with another tendency: inertia.

這是因為表面積最小化與另一個趨勢競爭：慣性。

To see that, look at one of the bulges that forms and disappears.

要看到這一點，看看形成又消失的其中一個凸起。

These are, of course, failed attempts by the liquid to form a sphere.

這些當然是液體試圖形成球體但失敗的嘗試。

Notice what must happen for a sphere, a droplet, to form.

注意，要形成一個球體，也就是一個液滴，必須發生什麼。

Some liquid must travel in the opposite direction of the stream's flow.

有些液體必須逆著水流的方向移動。

But this flow is opposed by inertia, as defined by Newton's first law.

但牛頓第一運動定律定義的慣性會阻礙這種流動。

an object in motion stays in motion with the same speed and in the same direction unless acted on by an unbalanced force.

動者恆沿直線等速運動，除非受到外力作用。

So the flowing liquid keeps moving downward, pulled by gravity, until the minimization of surface area forces some liquid to move up by creating these bulges.

所以流動的液體會因為重力持續向下，直到表面積最小化的趨勢迫使部分液體向上移動，形成這些凸起。

Upward flow occurs because at the ends of the bulge, where the stream is constricted, the pressure is higher than in the middle, so liquid flows toward the middle.

向上流動是因為在凸起的兩端，水流受擠壓處的壓力比中間高，所以液體會流向中間。

Although these bulges are large here, recall that wobbling near the top.

雖然這裡的凸起很大，但請回想一下頂端的擺動。

Each wobble moves a bit of liquid up, increasing as the stream descends, until eventually, as we see at the bottom of the stream, the surface area wins and droplets form.

每次擺動都會將一些液體向上推，隨著水流下降，這種情況越來越明顯，直到最後，就像我們在水流底部看到的，表面積獲勝，液滴形成。

The wobble observed at the top of the stream suggests how engineers can create precisely sized drops.

在水流頂端觀察到的擺動，顯示了工程師如何創造精確尺寸的液滴。

To create a stream with uniform drops that appear immediately, we need to vibrate the stream at a frequency near that of the wobble.

為了創造出能立即出現均勻液滴的水流，我們需要以接近擺動頻率的頻率來振動水流。

Notice that the drops form near the bottom of the screen.

注意看，液滴是在螢幕下方形成的。

But if I repeatedly tap the side of the cup, drops form soon after the stream exits the cup.

但如果我重複敲擊杯子的側面，液滴會在水流離開杯子後不久形成。

Here's a clever engineering application of this method to produce drops.

這是一個巧妙的工程應用，用這種方法來產生液滴。

It's the inkjet printers used to code packaging.

這就是用來列印包裝的噴墨印表機。

On the bottom of this almond can is a sell-by date.

這個杏仁罐頭底部有一個保存期限。

在布洛芬上，有一個到期日期。

Under the cap of the soda, a code used, perhaps in a contest.

在汽水瓶蓋下方，有一個用於抽獎的代碼。

而在這個清潔劑上，有一個序號。

These codes were printed by industrial-strength inkjet printers that throw ink up to an inch as products move by at speeds up to 2,000 feet per minute.

這些代碼是由工業級噴墨印表機列印的，這些印表機會在產品以每分鐘 2,000 英尺的速度移動時，將墨水噴射到最遠一英吋的距離。

These industrial printers, known as continuous inkjets or CIJs, create precision droplets using tapping to break a jet into droplets.

這些工業印表機，也就是連續噴墨（CIJ）印表機，透過敲擊來將噴射的墨水打散成液滴。

Ink from a reservoir is pumped through a nozzle.

The nozzle sprays a jet of ink onto a surface, a box, or a container.

噴嘴將一束墨水噴射到表面、盒子或容器上。

The jet's so powerful that the printer can print in any direction, from the top as I showed earlier, or horizontally as shown here.

這束墨水噴射力道很強，所以印表機可以朝任何方向列印，就像我剛才展示的從上方列印，或是像這裡所示的水準列印。

The letters or images created are composed of dots of ink.

產生的字母或圖像是由墨水點組成的。

To generate these droplets, an oscillator plate, a piezoelectric crystal, vibrates the nozzle.

為了產生這些液滴，一個振盪板，也就是壓電晶體，會讓噴嘴產生振動。

This is akin to tapping the cup to break a jet into droplets.

這就像是敲擊杯子讓噴射的墨水打散成液滴一樣。

I've shown the stream breaking into uniform droplets, but in practice, some small droplets called satellites also form.

我展示了墨流打散成均勻的液滴，但在實際應用中，也會形成一些稱為衛星的小液滴。

To select the right-sized droplets, the droplets are charged by electrodes and passed through high-voltage plates.

為了篩選出適當大小的液滴，這些液滴會被電極充電，然後通過高壓板。

The larger droplets are more highly charged, so deflect more than the smaller droplets.

較大的液滴帶電量較高，是以偏轉的幅度比小液滴來得大。

These satellites are collected and recycled into the ink supply.

這些衛星液滴會被收集並回收至墨水供應系統。

And to create the letters, some printers move the nozzle, others change the voltage to redirect the stream, and

而為了製造字母，有些印表機會移動噴嘴，有些則會改變電壓來重新導向墨流，

These commercial inkjet printers are only one example of the technological importance of creating precisely sized droplets.

這些商業噴墨印表機只是其中一個例子，說明瞭精確控制液滴尺寸在技術上的重要性。

But it illustrates how old technological applications that use droplets rely on the minimization of surface area as the driving force to form a droplet.

但它也說明瞭，使用液滴的舊式技術應用，如何仰賴表面積最小化來驅動液滴的形成。

我是 Bill Hammack，The Engineer Guy。