Many people who are not electronics and structure professionals often mistake themselves as a Chinese master. They think that microswitch and tap switch are actually a kind of thing. This can't be completely blamed for their ignorance. As a seller of switches, we have a great responsibility. Today we will take you to know the reason why microswitch and tap switch are reasonable What's the difference?
1、 The principle of light touch switch is to press the internal spring piece through the key handle to make the contact point between the internal spring piece and the base contact point, and make the switch on; the micro switch has a small contact interval and quick action mechanism, and the contact mechanism which uses the specified stroke and force to conduct the switch action is covered by the outer shell, They have actuators on the outside and have a smaller profile; the mechanical principles of both are the same, so they are called switches.
2、 The appearance of microswitch is different from that of light touch switch. This is distinguished by naked eye. Let's see the following figure to explain:
3、 The types of light touch switch include: waterproof type, straight plug type, patch type, lamp type, side press type, ultra thin type, sinking plate type, silica gel type, silent type, normally closed type and normally open type; the types of microswitch include: with pressing handle, non pressing handle, small micro motion, medium micro motion, large micro motion, vertical type, horizontal type and waterproof type.
4、 The internal structure of the tap switch and the internal structure of the microswitch are completely unnecessary. Let's look at the internal structure of the two!
The basic internal structure analysis of light touch switch:
Brief description of the tap switch:
(1) Touch the switch, also called the button switch, in English Name: touch switch, TCAT switch. Generally, it is called as its overall size: for example, 6 * 6 * 5, it is its length, width and height. It belongs to one kind of electronic switch, which has its own other than the wall switch of home. The difference is that the application field and its own structure function are different, so it is called electronic switch. It can be divided into: push and touch type with surface mounting. The difference between the two types is the difference between volume and welding form. The push-in type is mainly plug-in type large switch; the touch control type is mainly thin type of patch. The touch switch is made by pressing the handle to press the projectile to make the contact stroke between the projectile and the gun point be connected. So it can be divided into three forms: one is normally open, one is normally closed type, the other is double action type. There are three kinds of foot positions of switches: one is two foot switch, three foot switch, four foot switch and five foot switch.
(2) The switch is evolved from the pot chip, which is the first film switch used. The structure is single and the production speed is fast. But the product has a low life and single performance can not meet the market demand. According to the demand of product performance, simple pan chips have been gradually eliminated by the market. What follows is that we touch the switch, and its principle of use is the same. It's an upgrade to the pan, and its heart is the pan. It looks like a iron man.
In the early stage of use, consumers only have requirements for the quality and performance of products. With the improvement of market products and the improvement of consumption level, the quality and performance of products also begin to fail to meet the needs of consumers. People familiar with the switch know that the switch has its hand. In short, it is the strength of the switch. The switch has the power parameters of touch, key, toggle and micro motion. Industry standard: micro motion force 30-100gf, key strength 250-400gf, toggle strength 200-400gf, tap 50-400gf. The hand feeling and strength have a direct relationship. The smaller the positive and negative tolerance range of strength, the better the hand feeling, the larger the positive and negative tolerance range of domestic produced shrapnel, the value is positive and negative 50; the positive and negative tolerance of Korean produced shrapnel is relatively medium, with the value of positive and negative 30; the Japanese imported shrapnel is also the best piece in the world. The positive and negative tolerance of Japanese ternary shrapnel used by the product praise is very small, and the value is positive and negative 10. Conclusion: the higher the precision of the shrapnel, the better the touch of the switch.
The working principle of the switch: press the switch button at the working time point to turn on the switch. When the button is released, the switch is not only disconnected, but the internal structure of the switch is realized by the force of the metal shrapnel. The metal shrapnel is called projectile in the working principle, and the material of the projectile is two kinds. The spring sheet has two materials, namely, phosphor copper and stainless steel, silver plating and gold plating. Pinzan's gold plating and silver plating process are above 0.3um. The electroplating process directly affects the electrical properties and oxidation resistance of the product.
(3) The reason for the bad hand feeling is that there are many factors, such as unreasonable structure of switch, substandard material and plating process of shrapnel, deformation of shrapnel and large range of shrapnel error. How to ensure its hand feel, develop and produce reasonable structure, use stainless steel shrapnel, control the error of shrapnel and the rate of bad shrapnel. The quality of hand feeling will directly correspond to the sales volume and reputation of the products. A good brand, a good product on the switch hand feeling requirements are very high. The hand feeling has a great influence on the life of the switch itself, and the life of domestic shrapnel is between 3-5w; the life of Korean shrapnel is between 5-8w; the service life of Japanese ternary shrapnel used by pinzan is between 10-100w. Good shrapnel directly affects the hand, life and quality of the switch.
The height of the key handle can be customized according to the requirements. The thin surface of the patch is generally without the button handle, and it is covered by the film. The principle is the same. Plug-in handle height is 1.0, 1.5, 2.5, 3.5-28mm high, customized according to customer product requirements. There are two kinds of internal structure of the structure: silent, one is the common type of sound market, and the other is sound, and there is a "tick" clear and crisp sound. There are many kinds of key forces: 70gf, 90gf, 120gf, 160gf, 180gf, 200gf, 250gf, 300gf, 400gf and other customized forces. The selection of key strength is based on different products, such as mouse products, children products, medical products, smart home products generally use light strength, household appliances, automobiles, air purifiers and sports equipment generally use gravity. Positioning is based on the market demand of the products. The press force is closely related to the mechanical life of the light touch switch. The lighter the force, the higher the life. The service life is 3w-5w, 5w-8w, 8w-10w, 10W, 20W, 30W, 50W and 100W. The life of the imported shrapnel is greatly related to the choice of the switch shrapnel. The life of domestic shrapnel is 3w-5w, 5w-8w; the life of imported Korean shrapnel is 8w-10w; the service life of imported ternary shrapnel in Japan is 10W, 20W, 30W, 50W and 100W.
(4) The switch is made by the internal metal shrapnel to realize on-off. The distance between the metal sheet and the base bubble point is called travel. The stroke is divided into long stroke, short stroke and medium stroke, which is determined by the structure size and performance requirements of the switch itself. The shortest down limit of short stroke is 0.8mm, which is called small stroke, and generally ultra thin type is used. The middle stroke is between 0.13 and 0.3mm, which is generally used in plug-in type. Long range 3.0-0.5, generally used in silica key and gravity products. The smaller the travel, the smaller the press sound, and the higher the travel sound, the lower the life. According to the mechanism of switch itself, the stroke can be set, and the effect of sound and silence can be realized. Factors influencing the product: the most direct influence factor of stroke is the action force, which is usually divided into: light force (below 120g), gravity (over 300g) and standard force (150-250g), the shorter the stroke, the lighter the switch strength, the higher its life; the greater the force of the reverse stroke, the higher its life; the middle stroke is the most standard stroke, and its life is the highest Moderate and very ergonomic, so it is widely used.
The basic internal structure analysis of microswitch:
Brief description of microswitch:
(1) General terms
Microswitch: a contact structure with small contact interval and quick acting mechanism, which operates with specified stroke and specified force. It is covered by shell and has driving rod outside. (hereinafter referred to as switch) has contact: in switch type, compared with semiconductor switch with switch characteristics, mechanical switch with contact can realize the function of switch. Contact form: the electrical input and output circuit which forms the contact according to various purposes [(16) is displayed].
Rating: generally refers to the value as the guarantee benchmark for switch characteristics and performance, such as rated current, rated voltage, etc., provided that specific conditions (type of load, current, voltage, frequency, etc.) are the premise.
Resin fixing (plastic sealed terminal): after wiring with wires at the terminal, fix the part by filling resin, and eliminate exposed live parts to improve the anti dripping property.
Insulation resistance: refers to the resistance value between non connected terminals, between terminals and non charged metal parts, between terminals and ground.
Voltage withstand: the critical value that will not cause insulation damage after 1 minute high voltage is added to the specified measuring part.
Contact resistance: refers to the resistance at the contact part of the contact, but generally refers to the resistance value containing the resistance of the spring and the conductor at the terminal.
Vibration resistance: when the vibration microswitch is used by mistake, the contact closed by vibration does not separate within the specified time.
Impact resistance: durable impact refers to the impact of microswitch which will not be damaged by the impact of the machine during transportation or installation, and meets the impact within the range of action characteristics.
Misaction impact refers to the impact range that the contact closed by impact does not separate in the specified time when the microswitch is used.
(2) Terms for life
Mechanical life: refers to the switch life when the contact is not energized, and the over travel (OT) is set as the specification value at the specified operating frequency.
Electrical life: the switch life when connecting rated load on the contact, setting the over travel (OT) to 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 horizontal reference value
Indicates the level of failure with a reliability of 60% (λ 60).
λ 60 = 0.5 × 10-6/ time indicates that the failure rate is below the next one when the reliability is 60%.
(5) Shape and type of contact
(6) Contact interval
The contact spacing is specified as 0.25mm, 0.5mm, 1.0mm and 1.8mm. The contact spacing is the goal of design. When using, if the minimum contact interval is required, please confirm it and select it. The standard of the general contact interval is 0.5mm. For the same switch mechanism, the smaller the contact interval MD is, the higher the sensitivity is, the longer the mechanical life (life) is, but the DC circuit breaking performance, vibration resistance and impact resistance are unfavorable. Because the current switch will lose contact, the contact interval becomes larger, and the sensitivity decreases when MD is increased. Therefore, in order to realize the high sensitivity use of micro switch with contact interval of 0.25mm, it is necessary to keep a small switching current to reduce the contact loss caused by current switch. The products with large contact spacing have good anti vibration, shock resistance and breaking performance.
For MD (correspondence distance), see (10) action characteristic terms (page 745).
(7) Quick acting mechanism
The quick acting mechanism can make the movable contact move from one fixed contact to other fixed contacts quickly, and it is not affected by the operation speed as much as possible. For example, even if the switch is a knife, if the handle is operated quickly, the action will be faster. However, the mechanism related to the speed of the operating handle and the contact movement speed is not called the quick action type, but is called the slow motion type. The faster the switch speed of the contacts, the shorter the duration of the arc between the contacts.
In this way, the consumption and damage of the contact will be reduced, and the stable characteristics can be maintained. However, in this switch speed, in addition to effectively reducing the speed limit (economic speed) of arc quantity, there are also limits of mechanical problems. Especially, if the switch speed is too fast in closed circuit, the impact energy between movable contact and fixed contact will be larger, and the jump phenomenon (vibration or friction closing) formed by impact will generate arc, which will seriously lose contact, Sometimes it can not open the circuit, resulting in melting of the contact. The mechanism that performs this fast action usually uses a spring mechanism with dead point (the critical action point when one state jumps to another).
The following figure shows an example of the quick action mechanism of the microswitch formed after the combination of the tension spring and the compression spring.
The following describes the operation principle of the double throw (z) quick action mechanism.
As shown in the figure below, it is the relationship between the forces of the switch. In the free position without external force applied to the actuator, 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 movable contact C to fixed contact B.
Then, the force of part of the tension spring is applied by the driver to shift the tension spring. At this time, the forces F1 and F2 at point n will increase successively, with the angle close to 180 °, and soon, only F1 and F2 are in equilibrium state, namely F0 = 0. There is a slip from free position to F0 = 0
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