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Analysis of barrier free intelligent LED energy-saving shadowless lamp system design scheme

Operating light shadowless lamp, on the one hand, must be able to ensure the brightness of the operation room, so that doctors can accurately distinguish the outline, color and movement, on the other hand, it requires shadow lighting. Therefore, the operation lights should be provided with light intensity approaching to the sunlight quality (at least 100 thousand illuminance), and the brightness can be adjusted. In case of failure during operation, the spare bulb can be switched automatically in a short time. The operating lights also have to avoid generating heat while the light is bright. The operating light can also ensure that the color temperature is above 4000 color temperatures, close to the sun, make the eye more clear, and do not make the medical staff tired for a long time.

The operating room lighting system designed in this design must have the following requirements:

1. operation lighting luminance, specially designed precision optical system, high utilization rate of light, uniform illumination and high definition.

2. cold light, using LED as operating light source, without infrared radiation, has excellent cold light effect.

3. no shadow, intelligent control of multi light spot automatic focusing.

4. safe operation lighting, low voltage DC power supply and special power supply components, with overvoltage and short circuit protection functions to eliminate hidden dangers.

5. removable disinfection, using modern streamlined design to meet the operation room cleaning, disinfection and high standard laminar flow requirements;

In addition, the microcomputer digital method is used for stepless control, and it can also maintain its accurate color temperature, provide reliable guarantee for the doctor’s accurate judgement, and the brightness regulation and control have memory and display function and soft switch, which is convenient to adjust and use.

2.2 performance requirements
1. has sufficient illumination
The illuminance of shadowless lamp has been above 150000LUX, which is close to the brightness of summer sunshine. The actual illuminance is generally 40000 to 100000LUX, which will affect eyesight. While providing adequate illumination, we should avoid the glare of light beam on surgical instruments. Glare affects eyesight and vision, causing eye fatigue. The disadvantageous surgeon’s operation, the illumination of the shadowless lamp and the illuminance in the operating room should not be too different. Some illuminance standard stipulates that the illumination of the whole light is 1/10 of the illumination of the local illumination. The overall illumination of the operation room should be above 1000LUX.

2. high shadowless
The two optical design of LED light source improves the utilization ratio of light source and achieves long distance focusing, spot uniformity and shadowless.

3. low temperature
4. light quality is good
The so-called light quality is that the beam provided can really reflect the color and changes of blood and tissue. This property is generally referred to as chromaticity. It is expressed in terms of the chromatic index calculated by the distribution of light sources, and the best color rendering index is 100. Chromaticity has a great relationship with color temperature. The requirement is 6000K color temperature, the real color rendering is about 70-90, and the effective color rendering is close to 100.

5. easy to operate
Surgical shadowless lamp should be able to change position and direction continuously during operation. Operation must be simple, flexible, light and fast and effective. The sterilizing operation handle should be installed in the central part of the lamp body, and the advanced products are also equipped with deep light, deep light, color TV camera and ventilation device.

6. economy and security
The life of the LED light source is longer than 20000 hours, and the earthquake resistance is not easy to damage. LED adopts low voltage direct current power supply and is safe and energy saving.

Three. Scheme design

3.1 system function realization principle
Because the luminous efficiency of a single LED can not meet the requirements of the light intensity and uniformity of the operating shadowless light, it is necessary to use multiple LED arrays and require a reasonable arrangement and uniform distribution, making the light illumination of each target plane conform to the requirements, in order to determine the number and distribution rules of the LED. Although LED has high luminous efficiency and produces less heat, so many LED will produce a large amount of heat in a sealed box, and the temperature is even up to 60 C ~80, so the radiator and the heat dissipation channel must be reasonably designed to effectively reduce the thermal resistance of the system.

LED operation shadowless lamp consists of many lights, petal shaped, fixed on the balance arm suspension system, stable positioning, can do vertical or circular movement, can meet the needs of different heights and angles in the operation. The whole shadowless lamp has 216 high brightness white LED and 18 series connected into a group called high brightness LED string. It is made in parallel with 18 groups. Each group is independent of each other. If one group of other types of damage can continue to work, it has less influence on the operation. Each group carries out a constant current drive and accepts a microprocessor PWM pulse width control control according to the needs of the user. It can be stepless and flows through each LED of about 125~325 mA. The electrical schematic diagram of the LED shadowless lamp is shown in the picture.

Analysis of barrier free intelligent LED energy-saving shadowless lamp system design scheme

System hardware structure block diagram
3.2 hardware platform selection and resource allocation
This project uses EVK1105 as the design platform. AT32UC3A is a complete system level chip micro controller. It uses VR32 UC RISC and the working frequency is as high as 66MHz. It is designed for cost sensitive embedded applications, especially low power, high code efficiency and high performance. AT32UC3A integrated flash memory and SRAM memory, peripheral direct memory access controller (PDCA), and power management. In addition, there are various communication interfaces such as UART, SPI, TWI, synchronous serial controller, USB and Ethernet MAC.

3.3 system software architecture
The system is composed of the main control platform and terminal, the main control platform is EVK1105, the terminal uses the Atmel 51 Series MCU, so the software part of this system is also composed of two parts. The main control platform is responsible for receiving the user’s operation command, the terminal is responsible for receiving the command of the main console, and then controlling each step according to the instruction. The rotation of the machine, because we want to transform the plane coordinates on the operating table into the coordinates of our system, and move to a new coordinate each time, we should reestablish the coordinate system, the amount of calculation is relatively large. We make full use of the advantages of the AT32UC3A0512 with 32 bits and easily can be converted into the angle of the step motor by calculation. In order to reduce the amount of calculation of the terminal.

Analysis of barrier free intelligent LED energy-saving shadowless lamp system design scheme

EVK1105 main control platform is mainly responsible for receiving users’ instructions, such as the coordinates of the LCD touch screen, and the direction key to control the movement of the LED light focus on the operating table. After the main control platform receives the user instruction, the data is passed to the lower machine (12 MCU) by calculation, and the 12 MCU controls the two axis linkage of each LED respectively. So that at any time, the focus of 9 LED lights in the 12 LED lamps can focus on any point on the operating table to achieve the function of eliminating the shadow.

3.3.1 main control platform
LCD touch fast positioning, we use the LCD screen to use the dotted line to divide the operating table into 12 blocks, with a finger clicking one of them, the LED lamp above the operating table quickly moves to the center position corresponding to the corresponding block on the operating table, and then accurately adjusts the plane coordinates through the direction key to achieve the concentrated light point of the operating shadowless lamp in the hand. The location of any point on the table.

MCU control of 3.3.2 terminal
The key to realize two axis control by using single chip microcomputer is to first find the control method of two axis linkage which is suitable for single chip programming.

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Post time: Jun-01-2018