KR20020050862A - Measurement apparatus of dust density - Google Patents

Abstract

PURPOSE: A dust concentration measuring apparatus is provided to achieve improved reliability for the measurement value by minimizing error possibly caused during signal amplifying and converting processes. CONSTITUTION: A dust concentration measuring apparatus comprises a reference value sensor(15) for detecting whether the light generated from a light source has a predetermined intensity; a measurement value sensor(17) for detecting the intensity of the light scattered by dust; an amplifier(60) for amplifying the signals output from the reference value sensor and the measurement value sensor; a multiplexer(62) for multiplexing the signals amplified by the amplifier; a programmable gain amplifier(64) for amplifying the signal output from the multiplexer into a predetermined range; a bandpass filter(66) for filtering the frequency of a predetermined band from among the frequency amplified by the programmable gain amplifier; an analog-digital converter(68) for converting the filtered frequency into a digital signal; and a control unit(70) for receiving the digital signal from the analog-digital converter, estimating the amount of dust by comparing the reference value for light and measured value, and controlling the intensity of light source constant.

Description

Dust concentration measuring device {Measurement apparatus of dust density}

The present invention relates to a dust concentration measuring apparatus for measuring the concentration of dust, and more particularly, to a dust concentration measuring apparatus for reducing the error occurrence rate that can occur in the signal conversion process and amplification process by simplifying the signal flow system.

As the pollution problem becomes serious at present, the dust concentration measuring device is installed where dust is generated, and the amount of dust generated is measured. In order to measure the amount of dust generated, a dust concentration measuring apparatus using an optical system is used. The dust concentration measuring apparatus using such an optical system measures dust concentration by measuring light scattered by the dust.

1 is a schematic diagram of a dust concentration measuring apparatus using an optical system, and FIG. 2 is a signal flow diagram of the dust concentration measuring apparatus shown in FIG. 1.

As shown in Figure 1, the dust concentration measuring apparatus 10 is installed on one side of the chimney of the factory. Then, the first reflecting mirror 30 is installed on the opposite side to reflect the transmitted light to reflect the light transmitted from the dust concentration measuring apparatus 10 toward the dust concentration measuring apparatus 10 again.

The dust concentration measuring apparatus 10 includes a light emitting diode source 11 for generating light and emitting light, and a reference value detecting sensor 15 installed at the front upper portion of the LED source 11 to measure the intensity of the emitted light. ), And a measured value detection sensor 17 is installed at the front of the LED source 11 to measure the intensity of the reflected light, and the front of the LED source 11 is provided to distinguish the projection and the reflected light. 2 a reflector 19 is provided. The second reflector 19 is inclined at about 45 degrees, and a part of the light transmission is transmitted and the other part is reflected downward. Then, the other part of the projection reflected downward by the second reflector 19 is reflected by the third reflector 13 to reflect toward the reference value detection sensor 15.

The reflected light reflected by the first reflector 30 is reflected by the second reflector 19 to the measured value detection sensor 17, and a plurality of lenses 24, 26, 28) is installed so that the transmitted light is concentrated to go straight to the first reflector (30).

Meanwhile, as shown in FIG. 2, the reference value detecting sensor 15 detects whether the brightness of the light emitted from the LED source 11 is constant, and reflects the light scattered by the dust reflected from the first reflector 30. It is detected by the measured value detection sensor 17.

Light incident on the reference value detection sensor 15 and the measured value detection sensor 17 is represented by a current, which is an electrical signal, which is converted into a voltage using a current-voltage converter, and the signal is converted into a voltage by a first amplifier 41. Through the third amplifier 45 to amplify first, through the second amplifier 43 to have four gains, and to amplify the weak received signal into a signal suitable for digitization. 3rd amplification. In order to correct the bias of the amplified signal and shift the signal level, a plurality of digital to analog converter (DAC) 48 and analog to digital converter (ADC) 47 are used. Then, after the third amplifier 45 for fine tuning to obtain the desired digit, the value is digitized through the ADC 47, and the processor 50 measures the measured value detection sensor 17. The calculation process is performed to calculate the concentration of dust from the amount of incident light.

However, such a conventional dust concentration measuring device is a structure that adjusts the level of the electrical signals output from the reference value detection sensor and the measured value detection sensor after the first and second amplification by third level amplification, and may appear every time a plurality of amplifiers pass through. The problem is that you have an error.

In addition, the conventional dust concentration measuring apparatus has a structure that uses DACs and ADCs by receiving feedback data from a processor, and requires a plurality of DACs and ADCs, and accordingly, an electronic circuit constituting hardware is complicated.

The present invention has been made to solve the problems of the prior art as described above, and the object of the present invention is to provide a dust concentration measuring apparatus which minimizes errors that may occur during signal amplification and conversion by reducing signal amplification and conversion. have.

1 is a schematic diagram of a dust concentration measurement apparatus using an optical system,

2 is a signal flow diagram of the dust concentration measuring apparatus shown in FIG.

3 is a signal flow diagram of the dust concentration measurement apparatus according to an embodiment of the present invention,

4 is a perspective view illustrating three lens units illustrated in FIG. 3.

♠ Explanation of symbols on the main parts of the drawing ♠

10, 100: dust concentration measuring device 11: LED source

13, 19, 30: reflector 15: reference value detection sensor

17: Measured value detection sensor 62: Multiflux (MUX)

64: Programmable Gain Amplifier (PGA)

66: Band Pass Filter (BPF)

70: CPU (Central Processing Unit) 80: Motor

According to the present invention for achieving the object as described above, the reference value detection sensor for detecting whether the light transmitted from the light source is a constant intensity light, the measurement value detection sensor for detecting the intensity received by the light scattered by the dust and An amplifier for first amplifying a signal output from the reference value sensor and the measured value detection sensor, and a multiplex for multiplexing two signals amplified by the amplifier, the intensity of the scattered light In the dust concentration measuring apparatus for measuring the concentration of dust as a programmable gain amplifier (PGA) for amplifying a signal output from the multiplex to a predetermined range and a frequency band amplified from the programmable gain amplifier Bandpass Filter (BPF) to filter only frequencies of AD converter for converting to a hair signal and a control unit for receiving the digital signal from the AD converter and comparing the reference value and the measured value of the light to measure the amount of dust, and uniformly control the intensity of the light source for transmitting the light; A dust concentration measuring apparatus is provided.

The control unit of the present invention calculates a difference between the reference value and a constant value when the reference value does not match a constant value, converts the analog signal into an analog signal, amplifies it, and inputs the light to the light source to emit light of a constant intensity in real time. To control.

In addition, the controller of the present invention drives a motor for replacing a plurality of lenses installed in the advancing direction of light.

In addition, according to the present invention, the motor is installed in the center of the connecting bar connecting the three lenses having different transmittances arranged at 120 °, so that any one of the three lenses is driven in the direction of light propagation do.

In the following, with reference to the accompanying drawings a preferred embodiment of the dust concentration measuring apparatus according to the present invention will be described in detail.

In the dust concentration measuring apparatus of the present invention, the LED source, the first and second reflecting mirrors, the reference value detecting sensor, and the measured value detecting sensor are located in the same state, and the output signal is processed from the reference value detecting sensor and the measured value detecting sensor. As components of the signal processing system are modified, descriptions of the LED source, the first, second and third reflectors, the reference value detection sensor, and the measurement value detection sensor according to the related art will be omitted.

3 is a signal flow diagram of the dust concentration measurement apparatus according to an embodiment of the present invention, Figure 4 is a perspective view showing the three lens parts shown in FIG.

As shown in FIG. 3, in order to keep the brightness of the light source constant at all times, a reference value is read from the reference value detection sensor 15 to check whether the brightness of the light source has changed, and when it changes, the CPU (Central Processing Unit) 70 senses and adjusts using the DAC 72 and then amplifies it to adjust the voltage transmitted to the LED source 11 so that a constant light source is always emitted. The reference value detecting sensor 15 and the measured value detecting sensor 17 for adjusting the light source use the same type of light-receiving diode type sensor, and the signals output from the reference value detecting sensor 15 and the measured value detecting sensor 17 are several dozen. Since it is a very fine signal of several mV at uV, it is first amplified by the primary amplifier (PreAMP) 60. In order to transmit the amplified signal through a single transmission path, an electrical signal output from the reference value detection sensor 15 and the measurement value detection sensor 17 is transmitted to a transmission path through a MUX (multiplex) 62. do. The signal output from the MUX 62 is input to the Programmable Gain Amplifier (PGA) 64 to amplify to a desired level, and then, the BPF (band pass filter) 66 filters only a desired frequency of a predetermined band, and the ADC 68 ) To convert analog signals into digital signals.

The digital signal is transmitted to the CPU 70 to perform an algorithm operation for converting the brightness of the light source incident on the measured value detection sensor 17 into the amount of dust.

The signal obtained by passing through the PGA 64 is analyzed by the CPU 70 and the CPU 70 commands a command so that the amplification gain can be adjusted so as to amplify the desired signal. It is structured to be able to fit.

On the other hand, the CPU 70 drives three motors 80. The three motors 80 will be described in detail below, and the WDT (Watch-Dog Timer) 90 serves to initialize the CPU 70 when the CPU 70 malfunctions or fails due to operation and noise. do. In addition, the EEPROM (electrically erasable ROM) 95 serves as a memory to store various variables required by the computing and optical unit. In addition, the result calculated by the algorithm can be moved through the communication with the Data Logger using the RS485 communication protocol and serves to transmit the variables necessary for the operation in the Data Logger to the CPU 70 of the dust concentration measurement apparatus 100. .

In addition, the electrical signal input from the reference value detection sensor 15 to the CPU 70 detects whether the intensity of the light emitted from the LED source 11 is constant, and the light emitted from the LED source 11 at the CPU 70. The signal is converted into an analog signal through the DAC 72 so that it is always constant, and then the signal is amplified by the AMP 74 and input to the LED source 11. Therefore, the light emitted from the LED source 11 is detected in real time and controlled by the CPU 70 so that the light can be transmitted at a constant light intensity.

Meanwhile, as shown in FIG. 4, the first lens unit 24 positioned between the second reflector 19 and the convex lens 21, and the second lens unit 26 positioned in front of the convex lens 21. ), And the third lens unit 28 located in front of the first reflector 30, each of the three lenses 110a, 110b, and 110c is positioned at an angle of 120 °, and the three lenses 110a, 110b, When the center of the connecting bar 120 connecting the 110c, that is, the three lenses 110a, 110b, and 110c are considered as vertices of a triangle, the motor 80 is installed at the center of gravity. These three lenses 110a, 110b, and 110c are lenses 110a, 110b, and 110c that vary in the amount of light passing therethrough, and drive three motors 80 according to the state of light measured by the CPU 70. The lens 110a, 110b, and 110c of the three are rotated so as to be positioned in the direction of light propagation.

As described in detail above, the dust concentration measuring apparatus of the present invention undergoes two amplification processes and one signal conversion process in the process of inputting the electrical signal output from the reference value detection sensor and the measured value detection sensor to the CPU, thereby amplifying the signal. And it has the advantage that the reliability of the measured value is high by minimizing the error that can occur in the signal conversion process.

In addition, the dust concentration measuring apparatus of the present invention has the advantage that it can be used to replace the lens in accordance with the state of light.

Although the technical idea of the dust concentration measuring apparatus of the present invention has been described with the accompanying drawings, this is illustrative of the best embodiments of the present invention and is not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (4)

A reference value detection sensor for detecting whether the light emitted from the light source is a constant intensity light, a measurement value detection sensor for detecting the intensity by receiving the light scattered by the dust, and outputted from the reference value detection sensor and the measurement value detection sensor In the dust concentration measuring apparatus comprising an amplifier for firstly amplifying a signal, respectively, and a multiplex for multiplexing two signals amplified by the amplifier, the dust concentration being measured as the intensity of the scattered light, A programmable gain amplifier (PGA) for amplifying the signal output from the multiplex to a predetermined range; A band pass filter (BPF) for filtering only a frequency of a predetermined band from the frequency amplified by the programmable gain amplifier; An AD converter for converting the filtered frequency into a digital signal; And a control unit for receiving the digital signal from the AD converter and comparing the reference value and the measured value of the light to measure the amount of dust, and controlling the intensity of the light source for transmitting the light constantly. . The method of claim 1, The control unit calculates a difference between the reference value and a constant value when the reference value does not match a constant value, converts it into an analog signal, amplifies and inputs it to the light source, and performs real time control so that light of a constant intensity can be emitted. Dust concentration measuring device. The method according to claim 1 or 2, The control unit dust concentration measuring device, characterized in that for driving a motor for replacing a plurality of lenses installed in the advancing direction of the light. The method of claim 3, wherein The motor is installed at the center of the connecting bar connecting the three lenses having different transmittances arranged at 120 °, dust concentration, characterized in that any one of the three lenses are driven to be located in the direction of light propagation Measuring device.