A medical oxygen flowmeter of intelligent design and implementation (1)

O introduction

For a long time our medical system in patients with oxygen, oxygen flowmeter used floating monitoring patient flow of oxygen.

The flow just medical basis, but cannot be used as a basis for billing, and patient billing at the time of oxygen. This billing mode from an objective point of view there is a lot of irrationality, patients in the hospital and have made a certain contradictions, with the advancement of health care reform, this conflict have become increasingly prominent, urgently need a convenient and reliable, low cost can automatically record the amount of oxygen patients medical oxygen flowmeter to resolve patient oxygenous billing issues.

Using modern sensor technology seems to be difficult to achieve automatic measurement of oxygen quantity and record, however, the sensor components and packaging materials to the patient's health is a big problem, need to go through a large number of demonstration and experimentation, and the need for specialized sector evaluated and certified, this allows the device cost increase, to popularize work difficult.

Through the hospital's existing oxygen system study finds existing oxygen system monitoring oxygen flow of float flowmeter valve switch handle position (rotation angle) determines the size of the oxygen flow to handle location and oxygen flow has certain correspondence.

By automatically read switch handles rotation angle can be instantaneous flow of oxygen, the use of single-chip timing and calculation can reach patients oxygen accumulated in the process of oxygen.

1. system composition and basic principles

This design is a simple, reliable and practical medical oxygen flow measurement system, which utilizes the existing oxygen system metal oxygen flowmeter valve float switches handle the rotation angle and dependency between oxygen flow measurement.

Install the valve handle an encoding, the encoder disks along radial divided into 4 equal parts, circumference, area is divided into 16 equal sectors, will this 16 sectors in clockwise direction on radial 4 equal area according to the rules for encoding binary numbers and are coloured black and white (black and white, on behalf of the "O" on behalf of the "1") so that coding disc on forms to OH ~ 15H indicates that 16 handles turn angle different locations, which represent different oxygen flow.

In the coding side of the disc to install 4 on infrared transmitter and receiver, on their respective alignment coding 4 radial coding region, when the valve handle rotation infrared receiver can receive a coding sequence, and transmits it to AT89C55 microcontroller. AT89C55 MCU on the coding for analysis and comparison to determine the direction of rotation of the lever, the angle, rotation, coils and eventually stop position to calculate the appropriate oxygen flow, while recording the oxygen of the start time and end time, ultimately the calculated the total amount of oxygen in patients. Appear during the oxygen inhalation time, flow, oxygen content, and other information and provides a query function. At the end of the oxygen through RS 232 serial interface to the oxygen delivered to host billing information to your computer.

The system consists of coded disk, infrared reading device, oxygen flow records and computing devices, display devices, operation panel and RS 232 serial interface and application software, etc.

Its system design diagram shown in Figure 1.

2 hardware implementation of the programme

2.1 coded disk

As shown in Figure 2 is encoded disc thickness of 2 mm diameter is 80 mm plastic garden plate, coded disk installed on the floating ball valves for oxygen flowmeter, coding on the handle of "0H" position corresponds to the valve in the closed position, the remaining 16 position corresponds to different oxygen flow.

2.2 infrared reading device

Infrared light reading device is composed of 4 on reflective infrared switch formed using coding disc black and white areas on infrared reflectivity of different recognition of different encoding.

Black on infrared reflection is weak, the receiving authority in the closing state, white on strong infrared reflection, receiving tube saturation. Signal directly, access AT89C55 P1 port. Its main circuit shown in Figure 3.

2.3 oxygen flow records and computing devices

This design uses AT89C55 microcontroller as the oxygen flow records, calculation, the core of the query, by providing real time clock DSl2887.

SCM per minute read coded information and calculates the flow while performing storage and display, SCM through disruptive accept operation keys generated interrupt signal, call the subroutine completion time settings, flow setting, query, clear, and so on.

2.4 display unit

Display device using SMGl9264 LCD module circuit as the monitor, its main circuit shown in Figure 4.