The development of smart cards has experienced three stages of magnetic cards, contact IC cards and RF cards. Since the RF card has an unparalleled advantage in contacting the IC card, the RF card type product will inevitably replace the product that contacts the IC card, just like the IC card replaces the magnetic card. It is a technological replacement process that is not about the will of people. The application of smart cards in door locks has also gone through three stages. The traditional market for magnetic card locks has gradually disappeared, and the use of contact IC card locks has become quite common. RF card locks are currently on the rise in the country. This article will focus on the technical status of RF card door lock products.
In the application of electronic door locks: RF card reading is convenient and fast, and the service life of locks and cards is long. There are many supporting manufacturers for “one card†system, and RF card lock is definitely the mainstream product of electronic door locks. In 5 years, it will completely replace the use of IC card locks in domestic hotels.
RF card electronic door lock is a high-tech product that combines mechanical, radio frequency technology and micro-power technology. It has certain technical difficulties. From the technical point of view, the following four aspects are perfected to be a mature RF card electronic door. lock:
1, the battery life
As an electronic door lock, it is required to use a battery that is easily available in the market. General now use AA alkaline dry batteries, from a cost and environmental point of view, the battery life for as long as possible, the number of cells as possible. From the industry point of view Manufacturer: battery life 5 dates ranging from 18 months, whether or not the real solution lies in "low-power locks Fei Guo Sheng Shi Xing urgent ridiculed gown and section 6 batteries, mainly??? The problem lies in whether the design of the drive part and the electronic part of the lock body is reasonable, and the problem is better solved. The micro power consumption problem of the lock circuit is a technical difficulty of the RF card electronic door lock. The following is further analyzed.
In low-power system design, the system's low-power design is divided into two aspects: 1. Essentially low power consumption, 2. Control low power consumption. On the one hand, the power consumption of the system is not good.
The so-called essential low power consumption means that the electronic components used are all "low-power" components. The common feature of most low-power devices is low-voltage power supply. In circuit design, components should be considered. Power consumption is as low as possible among different devices in different system states. For example, Japan's EPSON, the United States TI has a large number of optional devices in this regard. If you do not do well in the essential low power consumption, the power consumption of the system will not be discussed.
The so-called control low-power problem means that when the system is working, the total power consumption of the system is minimized by controlling the power supply of each part. If the controllable part is neglected in the system, the power consumption of the system will increase, for example, the system. In the detection of the switch signal, the pull-up portion is not controlled, and then the switch consumes power when it is in a state.
For the RF card lock, talk about controlling low power consumption. Once components are selected, the system's low-power issues are focused on how to minimize control power consumption. Some designers use the ammeter to measure the actual power consumption of the data when measuring the power consumption of the system, rather than the power consumption of the system, because the average power consumption of the system is not easy to actually measure due to different parts of the circuit. Another problem is When the actual value of the high current transient operation does not represent its true power consumption (measurement tool selection problem), the average power consumption of the system must be designed by theoretical calculations at the beginning of this part of the design. RF card electronic door locks are in a static waiting mode for reading cards in most of the time. In many electronic door locks, the power consumption of reading and completing the driving motor is similar, but this part is limited due to the limited number of times. It has little effect on the battery life. The electronic door lock is waiting for the card reading status for more than 99.5% of the time. The average power consumption of this state determines the battery life.
Since the door lock cannot read the card at all times (too much power consumption), there must be a detection method to detect that the card is close to the door lock. For the sake of cost and power consumption, the electronic detection method is well solved by infrared detection. The problem is that the current electronic door locks in the market basically use this method. In general, the detection of the next second is 5 times, so that the user does not feel a sense of pause. If the power consumption is reduced and the number of detections is reduced, the lock response is slow. The detection circuit consumes several tens of milliamps (which is very large for the battery ), so it is necessary to control this part of the power consumption (about 50% of the system's average power consumption). It is difficult to truly reflect the power consumption of this part of the measurement tools, so you must calculate them in the design, otherwise you will find that the actual battery life is not the same as your design parameters.
2, the card is accurate and fast
The speed of reading a card has two effects: 1. The number of times the card is detected every second, 2. The speed of reading the data on the card.
In principle, the more times the power consumption is allowed, the better; the data of the reading card is reasonably related to the design of the card reading program, and since the card reading coil is close to the metal part of the lock body, it is necessary to pay attention to the blind spot of the card reading, and the card frequency deviation problem Can design a good card reader electronic card lock.
3, the working stability of the door lock
The working stability of the door lock is related to the selected components, the rationality of the circuit design, and the stability of the control program. In terms of components, devices with strong environmental adaptability should be selected: temperature range, voltage, current overload capability, etc. Since the failure rate of the circuit is proportional to the number of components, it is necessary to increase the integration of the circuit as much as possible.
The general assessment stability is to let it work continuously, and the longer the effective working time, the more stable it is.
Shenzhen Yuanwei's RF card locks solve the above problems very well. The main technical indicators of the products are as follows: Voltage: 4.5-6.5V; Current: <40UA (Static average current, 4 to 5 batteries can work for 12-8 months) ); card reading time: an average of 0.25 seconds; single-chip solution.
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