Many people who are not majoring in electronics and structure often mistakenly think that they are Chinese masters. They think that micro switch and touch switch are actually a kind of thing, which can't be completely blamed for their ignorance. As a switch seller, we have a great responsibility. Today we will take you to have a good understanding of the reason of micro switch and touch switch What's the difference?
1、 The working principle of the light touch switch is to press the internal shrapnel through the key handle to make the internal shrapnel contact with the contact point of the base, so as to make the switch conduct; the micro switch has a micro contact interval and a quick action mechanism, and the contact mechanism which uses the specified stroke and force to switch is covered by the outer shell, There is a transmission outside, and the shape is small; the mechanical principles of the two are the same, so they are called switches.
2、 The appearance difference between the micro switch and the touch switch can be distinguished by naked eyes. Let's see the following illustration:
3、 The types of light touch switch are: waterproof type, in-line type, patch type, light type, side press type, ultra-thin type, sink plate type, silica gel type, silent type, normally closed type, normally open type; the types of micro switch are: pressure handle, non pressure handle, small micro motion, medium micro motion, large micro motion, vertical type, horizontal type, waterproof type, etc.
4、 The internal structure of touch switch and micro switch are not used at all. Let's take a look at the internal structure of both!
Analysis of the basic internal structure of the touch switch
Brief description of touch switch:
(1) Touch switch is also called key switch, English Name: touch switch, TCAT switch. Generally, it is called by its dimensions: for example, 6 * 6 * 5 is its length, width and height. It belongs to a kind of electronic switch, which is different from the household wall switch. The difference lies in the different application fields and the different structure and function, so it is called electronic switch. Divided into: push type and surface mounted touch type. The difference between the two types lies in the volume and welding form. The push type is mainly plug-in type, and the surface mounted touch type is mainly ultra-thin type. The light touch switch applies pressure to the shrapnel by pressing the handle to make the contact stroke between the shrapnel and the shot point conduct. So it can be divided into three forms, one is normally open type, one is normally closed type, one is double action type. There are also three kinds of foot positions of switches: two foot switch, three foot switch, four foot switch and five foot switch.
(2) Switch is evolved from wozipian. Wozipian is one of the earliest used membrane switches. Its structure is single and its production speed is fast. However, the product has low life and single performance, which can not meet the market demand. According to the increasing demand for product performance, simple Wozi tablets have been gradually eliminated by the market. What follows is that we touch the switch, and its principle is the same. It is the upgraded version of Wozi slice, and its heart is Wozi slice. Looks like iron man.
At the beginning of use, consumers only have requirements for the quality and performance of products. With the improvement of market products and consumption level, the quality and performance of products can not meet the needs of consumers. Anyone familiar with the switch knows that the switch has its hand feel. In short, it is the strength of the switch. Touch, button, toggle and micro motion all have strength parameters. Industry standard: fretting strength 30-100gf, button strength 250-400gf, toggle strength 200-400gf, touch strength 50-400gf. The quality of hand feeling is directly related to the strength. The smaller the positive and negative tolerance range of strength, the better hand feeling. The positive and negative tolerance range of domestic shrapnel is larger, with a value of plus or minus 50; the positive and negative tolerance range of Korean shrapnel is medium, with a value of plus or minus 30; the shrapnel imported from Japan is also the best shrapnel in the world, with a value of plus or minus 10. Conclusion: the higher the precision of shrapnel, the better the touch of switch.
The working principle of the switch: when the switch button is pressed, the switch can be connected. When the button is released, the switch will be disconnected. Its internal structure is realized by the force of metal shrapnel. The metal shrapnel in the working principle is called shrapnel for short. There are two kinds of shrapnel materials. The shrapnel is made of phosphor copper and stainless steel. There are two electroplating processes, silver plating and gold plating. The gold plating and silver plating processes of pinzan are above 0.3um. The electroplating process directly affects the electrical performance and oxidation resistance of the product.
(3) There are many reasons for bad handle, such as unreasonable switch structure, substandard shrapnel material and electroplating process, shrapnel deformation and large range of shrapnel error. How can we guarantee its handle, develop and produce reasonable structure, use stainless steel shrapnel, and control the error and defect rate of shrapnel. The quality of the handle will directly affect the sales volume and reputation of the product. A good brand and a good product have very high requirements for the handle of the switch. The life of the switch itself is also greatly affected by the handle quality. The life of domestic shrapnel is between 3-5w times; the life of Korean shrapnel is between 5-8w times; the life of Japanese Sanyuan shrapnel used by pinzan is between 10-100w times. Good shrapnel directly affects the handle, life and quality of the switch.
The height of the key handle can be customized according to the requirements. The thin surface of the chip usually has no key handle and is covered by a film. The principle is the same. The plug-in handle is 1.0, 1.5, 2.5, 3.5-28mm high, which is customized according to the customer's product requirements. Its internal structure has two kinds, one is silent, the other is sound, the general market type is sound, there is "tick" clear sound. There are many kinds of button strength: 70gf, 90gf, 120gf, 160gf, 180gf, 200gf, 250gf, 300gf, 400gf and other customized strength. The selection of button strength is based on different products. For example, mouse products, children's products, medical products and smart home products generally use light strength, while household appliances, automobiles, air purifiers and sports equipment generally use gravity. It is positioned according to the market demand of products. There is a great relationship between the strength of the button and the mechanical life of the light touch switch. The lighter the strength is, the higher the life can be. The life is 3w-5w, 5w-8w, 8w-10w, 10W, 20W, 30W, 50W and 100W. The life of domestic shrapnel is 3w-5w and 5w-8w; the life of imported shrapnel from South Korea is 8w-10w; the life of imported shrapnel from Japan is 10W, 20W, 30W, 50W and 100W.
(4) The opening and closing of the switch is realized by the force of the internal metal shrapnel. The distance between the metal sheet and the bubble point of the base is called the stroke. The stroke is divided into long stroke, short stroke and medium stroke, and the stroke is determined according to the structure and performance requirements of the switch itself. The shortest lower limit of short stroke is 0.8mm, which is called small stroke. Generally, ultra-thin type is used. The middle stroke is between 0.13-0.3mm, which is generally used in plug-in type. Long stroke between 3.0-0.5, generally used in silicone keys and gravity products. The smaller the stroke is, the smaller the sound of the button will be. On the contrary, the higher the stroke is, the greater the sound will be and the lower the service life will be. The stroke can be set according to the mechanism of the switch itself, which can achieve the effect of sound and silence. Influencing factors of products: the most direct influencing factor of the length of stroke is action force, which is usually divided into light force (below 120g), gravity (above 300g) and standard force (150-250g). The shorter the stroke is, the lighter the strength of the switch is, and the longer its service life is; on the contrary, the greater the stroke is, the greater the strength is, and the longer its service life is; the middle stroke is the most standard stroke, and the longer its service life is Moderate and very ergonomic, so it is widely used.
The basic internal structure of microswitch is analyzed
Brief description of microswitch:
(1) General terms
Microswitch: it is a kind of switch with micro contact interval and quick action mechanism. It is a contact structure with specified stroke and force for switching action. It is covered by a shell and has a driving rod outside. (hereinafter referred to as switch) has contact: in the type of switch, compared with semiconductor switch with switching characteristics, the function of switch is realized by mechanical switch of contact. Contact form: the electrical input and output circuit of the contact formed according to various uses (shown in (16)).
Rated value: generally refers to the value used as the guarantee reference of switch characteristics and performance, such as rated current, rated voltage, etc., whose premise is specific conditions (load type, current, voltage, frequency, etc.).
Resin fixing (plastic sealing terminal): after wiring with wire at the terminal, fix the part by filling resin to eliminate the exposed live parts to improve the anti dripping property.
Insulation resistance: refers to the resistance value between unconnected terminals, between terminals and uncharged metal parts, between terminals and ground.
Withstand voltage: the critical value that will not cause insulation damage after 1 minute high voltage is applied to the specified measuring position.
Contact resistance: refers to the resistance of the contact part of the contact point, but generally refers to the resistance value of the conductor including the spring and terminal part.
Vibration resistance: when the misoperation vibration microswitch is in use, the vibration range of the contact which is closed by vibration is not separated within the specified time.
Impact resistance: durable impact means that the microswitch will not be damaged by the mechanical impact during transportation or installation, and meet the impact within the range of action characteristics.
Misoperation impact? Refers to the impact range in which the contact closed by impact does not separate within the specified time when the microswitch is in use.
(2) Terms about life span
Mechanical life: refers to the switch life when the contact is not electrified and the overtravel (OT) is set to the specification value at the specified operating frequency.
Electrical life: the life of the switch when the rated load is connected to the contact and the overtravel (OT) is set as the specification value at the specified operating frequency.
(3) Standard test status
The test conditions of the switch are as follows.
Ambient temperature: 20 ± 2 ℃, relative humidity: 65 ± 5% RH, air pressure: 101.3kPa
(4) N level reference value
Represents the failure level with a reliability of 60% (λ 60).
When λ 60 = 0.5 × 10-6 / time, it means that the failure rate is less than times when the reliability is 60%.
(5) Shapes and types of contacts
(6) Contact interval
The contact spacing is 0.25 mm, 0.5 mm, 1.0 mm and 1.8 mm. Contact spacing is the goal of design. When using, if the minimum contact interval is required, please confirm it separately and select it. Generally, the standard of contact spacing is 0.5mm. For the same switch mechanism, the smaller the contact spacing, the smaller the MD, the higher the sensitivity, and the longer the mechanical life (life), but the DC circuit breaking performance, anti vibration and anti impact are disadvantageous. Because the current switch will lose the contact, the contact interval will become larger, and the sensitivity will decrease with the increase of MD. therefore, in order to achieve high sensitivity, when using the micro switch with 0.25 mm contact interval, it is necessary to keep a small switching current to reduce the contact loss caused by the current switch. Products with large contact spacing have good vibration resistance, impact resistance and open circuit performance.
For MD, please refer to (10) action characteristic terms (page 745).
(7) Quick action mechanism
The quick action mechanism can make the movable contact move quickly from one fixed contact to other fixed contacts without being affected by the operation speed as much as possible. For example, even for knife switch, if the handle is operated quickly, the action will be faster. However, the mechanism that the speed of the handle is related to the speed of the contact movement is not called the quick action type, but the slow action type. The faster the switching speed of contacts, the shorter the duration of arc between contacts.
In this way, the consumption and damage of the contact will be reduced, and the stable characteristics can be maintained. However, in addition to the speed limit (economic speed) which can effectively reduce the amount of arc, there are also limits of mechanical problems. Especially, if the switching speed is too fast in closed circuit, the impact energy of movable contact and fixed contact will increase, and the jumping phenomenon (vibration or friction closure) formed by impact will produce arc, which will seriously damage the contact, Sometimes the circuit can not be opened, resulting in melting of the contact. Generally, the spring mechanism with dead point (the critical action point when one state jumps to other states) will be used for this kind of quick action mechanism.
It shows an example of forming a quick acting mechanism of a micro switch by combining a tension spring and a compression spring.
The following is about the action principle of double throw (z) quick action mechanism.
For the relationship between the force of the switch. In the free position without external force applied to the driver, the reaction force F1 of the compression spring is in equilibrium due to the influence of two forces F2 and F0. F0 is the pressure to push the movable contact C to the fixed contact B.
Then, a force is applied to a part of the tension spring by the driver to shift the tension spring. At this time, the force F1 and F2 at N point will increase in turn, and the included angle is close to 180 degrees. Soon, only F1 and F2 are in balance, that is, F0 = 0. There is a slip from the free position to F0 = 0
Dynamic action will make the contact move to the horizontal direction and further bend the compression spring. From the position of F0 = 0, by further applying external force to make the tension spring slightly shift, a force in the opposite direction - F0 will be generated, which will bend the movable contact C with the maximum strength of the compression spring
Press out from the down direction, the movable contact C will move through the space to the opposite fixed contact a.
Based on this principle, the microswitch switches the contact with the inherent switching speed (leaving speed) of the switch, which has nothing to do with the speed of the external force generated when the tension spring is pressed. The position when F0 = 0 is called the action position, which is based on the position where a part of the tension spring passes through the dead point
This is the same.
When the external force is eliminated for the reset operation, it is also based on the same principle, and the bending reaction force of the spring is the original force of the reset.
5、 The application range of micro switch and touch switch is different
1. Microswitch is divided into small current, medium current and large current, so it is widely used in the harsh environment of electronics, machinery, medical, automobile, aviation and so on;
2. Touch switch only has small current, there is no large current products, so it is widely used in consumer electronics and other small current control board.
6、 Summary of micro switch and touch switch both have the same, but also need not, so we according to the above analysis and explanation, follow-up can be very simple to distinguish the two. If you need both switches, check the contact information below!
QQ Online