Comparison of Tactile & Non Tactile Rubber Keypad Switch
What is a rubber keypad switch?
Normally, a keyboard is a keyboard in which about 100 of these rubber keypad switches are lined up in a row. There is a wide range from those that emphasize cost to those that pursue a feeling of a keystroke. These combine and make your product work.
What is the common key switch?
A common key switch on relatively inexpensive keyboards is the so-called “membrane method. There is conductive wiring on the sheet-like membrane. And the structure generally comes with a rubber part that dents when pressed, called a “rubber dome. It sticks two pieces together to give a feeling of a keystroke.
Significance of membrane method
The advantage of this rubber keypad switch method is the low manufacturing cost. And it is sometimes used as an accessory for PCs and most of the products on the market for about 1000 yen. The weak point is that the keys cannot be exchanged individually. If even one break, you’ll have to replace the entire keyboard.
An overview of the pantograph mechanism
Many notebook PCs and thin keyboards use the “pantograph method,” which is an advanced version of the membrane method. A pantograph mechanism like the one on the top of a train is built to prevent the key’s end from wobbling.
General membrane method
General membrane method (left) and pantograph method (right). Although it can be manufactured at a low cost, it lacks durability. In contrast, the “capacitive non-contact method” is known as a high-class method. The rubber keypad switch has different compositions.
Since there is no mechanical contact between the electrodes as in other methods, there is no concern that the contacts will wear, and the durability and reliability are excellent. In the past, it was used by various manufacturers such as IBM PC keyboards. It is often called “Topre Switch” after the name of the developer.
Why is the Capacitive non-contact method important?
The main of the self-made keyboard is the mechanical method. The membrane method is difficult to differentiate and improve the feeling of keystrokes, and the capacitive contactless method is difficult to implement in principle, so it cannot be said that it is suitable for self-made at present.
The rubber keypad switch, a key method that is currently the mainstream of homebrew keyboards, is the “mechanical method.” As the name implies, it is a key switch with mechanical contacts, and there are switches with various structures.
Key switches used for homebrew keyboards
Among them, the key switches used for homebrew keyboards are roughly divided into two systems, “Cherry MX series” and “ALPS series.”
1-ALPS key switch
The ALPS key switch has been used by Apple on many models in the past, and many Macintosh users of yesteryear may have touched it. However, this ALPS switch manufactured by Alps Electric has already been discontinued, and new key switches are not available. The main way to get it is to remove it from a used rubber keypad switch or buy a clone made by Matias, Canada.
2-Cherry MX rubber keypad switch
On the other hand, Cherry MX is a key switch still manufactured by German Cherry. Therefore, most of the keyboards sold as mechanical keyboards as of 2020 are equipped with Cherry MX key switches. Even in homebrew keyboards, many parts are made based on Cherry MX, which is the de facto standard.
Cherry MX switch ALPS, key switch
Examples of Cherry MX switches (left) and ALPS switches (right, the photo is the unknown manufacturer). If you want to start your own keyboard from now on, it is safe to choose the Cherry MX series. Key switches of rubber keypad switch are classified into three types of feel and weight
- Firstly, the main parameter that distinguishes a key switch is the feel of the key
- Second, the feel of the keys, that is, the feedback from the key switches, is very important.
- Lastly, the user presses a key switch and can confirm that it is electrically transmitted to a machine.
How to mechanically create key switches?
Machines that use a touch panel as the main input interface, such as a smartphone, do not have the feel of a switch, so the input sensation is fed back to the user with the sound and vibration from the speaker, but it is possible to mechanically create it with a key rubber keypad switch.
The feel of such a key switch is classified into three categories: linear, tactile, and clicky. Each characteristic is divided by the feel and sound of the fingertips. “Linear” where the key goes down smoothly. The linear type key switch does not get caught in the vertical movement of the key switch.
Comparison of the two membrane switches.
When the key is pressed and does not return clear tactile feedback like other types, conversely, it is a type that clearly shows the weight. It happens when pressed and the smoothness due to the accuracy during manufacturing. This happens to variety of keypad switches.
“Tactile” characterized by a “squeaky” resistance
The tactile type, rubber keypad switch, behaves as a “bump” in which the load changes during the pressing of the key, as opposed to the linear type, which has no feedback at all. It is difficult to express in letters, but the feeling, including this resistance feeling such as “Kun” while pressing, is called “tactile feeling.”
The author thinks that it is easier to stick to than other types because there is no sound when pressed, but there is clear feedback on the weight of the fingertips. In Cherry MX, “Cherry MX Brown (brown axis)” corresponds.
“Clicky” overview with transparent rubber keypad switch
Clicky is a type of switch that adds clear sound feedback in addition to bumps like tactile. Since the click, rubber keypad switch sound is easy to understand, it is sometimes used for the operation panel of machines. While you can clearly see that you are typing, you may feel that the sound is noisy if you are typing continuously,
How does “Load” determine the strength of the keypress?
Next to the three feels listed above, the load is the most important. In other words, it is the weight when pressing a key, but the standard spec is 45g when the switch is turned on (operating point) and 60g when it is completely pressed down (bottoming out).
The feeling of keystrokes changes depending on the critical switch making (precision) and the combination of keycaps. There are also personal preferences such as being too heavy and tired or being too light and reacting just by placing your finger, so for the time being it is a good idea to buy a suitable item and select the next one based on that.
Required process before assembly Check the contents of the kit
Many kits come in the form of a board or set of electronic components. They contain the circuit and not a rubber keypad switch. These are the parts where each taste comes out, and it is also related to the final appearance and keystroke feeling.
Therefore, when you buy a kit, check the number of keys, and don’t forget to buy switches and caps. First is the board (PCB). This is a board with electrical wiring that connects key switches and other electronic components, and the electronic components are soldered to the board for assembly.
Domestic self-made keyboard
Most of the domestic self-made keyboard kits are soldered by yourself, but some overseas products and a small part of Japan have already soldered parts. Various electronic components soldered to the PCB will be described later. There are many small parts, so make sure you have the right number before assembling.
PCBs are rarely seen on general keyboards, but much homemade rubber keypad switch has a beautiful design on the PCB. Other electronic components. Basically, soldering these electronic components to the PCB is most of the assembly.
What is a key switch plate?
The key switch plate is a plate for fixing the key switch. Depending on the kit, there are various materials such as acrylic, PCB material, and metal. It is one of the important parts that affect the feeling of keystrokes because the hardness and flexibility of the material differ depending on the material.
On the photo is a plate made of the same material as the PCB that comes standard with the kit. You can order separate type of keypad switches according to your project. Since there are many types of case structures, we will omit them here, but most of the domestic rubber keypad switches. This includes Corne Cherry, have adopted a “sandwich structure” using an acrylic plate.
Composition of switch plate in rubber keypad switch
This is a structure in which a PCB on which electronic components are mounted is sandwiched between a key switch plate and a bottom plate. This is the bottom, and screwed. It is popular and popular among keyboard designers because it is easy to make color variations with acrylic.