JP3004457U - Infrared gas analyzer - Google Patents

Abstract

(57) [Abstract] [Purpose] In the standby mode where measurement is not performed, the backlight of the liquid crystal display unit is turned off to extend the life of the backlight of the liquid crystal display unit and also promote energy saving. To provide a gas analyzer. [Configuration] In an infrared gas analyzer that detects a specific measurement target component in a sample gas SG and displays a measurement result on a display unit, when the standby mode state continues for a predetermined time, the back of the liquid crystal display unit 28 It has a function to turn off the light.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of an infrared gas analyzer such as an exhaust gas analyzer used for measuring vehicle exhaust gas during use during vehicle inspection.

[0002]

[Prior art]

 The exhaust gas analyzer measures the components to be measured in the exhaust gas based on the following measurement principle. That is, when infrared rays pass through the exhaust gas, infrared rays in the wavelength range peculiar to the measurement target component contained in the exhaust gas are absorbed, and the concentration of the measurement target component can be measured by measuring the amount of absorption. it can.

At this time, the basis for dealing with the absorption of light is the Lambert-Beer's law, which is expressed by equation (1). ^{_{I t = I 0 · e -kCl}} ...... (1) I 0: intensity of incident light I _t: the intensity of the emitted light k: extinction coefficient l: thickness of the light absorbing layer C: sample concentration

Therefore, the output obtained from the exhaust gas analyzer when the concentration of the sample is C is obtained by the equation (2). _{I t = I 0 · (1} -e -kCl) ...... (2)

FIG. 3 is a block diagram schematically showing the configuration of an exhaust gas analyzer equipped with an analysis unit based on the above measurement principle. In this figure, 1 is an analysis unit and 2 is various input keys. The operation unit 3 displays an analysis result, and a display / external output unit that displays the current state of the device, etc. as necessary. 4 controls each unit of the device based on a key input from the operation unit 2 and performs analysis. A control / arithmetic unit that performs concentration calculation based on a signal from the unit 1 and stores the obtained data, and is, for example, a microcomputer.

FIG. 4 schematically shows the structure of the gas flow in the exhaust gas analyzer. In this figure, 5 is a housing, for example, a sample gas inlet 6 is formed on the front surface thereof. The sample gas introduction port 6 is connected to the analysis unit 1 provided in the housing 5 via a sample gas flow path 10 including a dust filter 7, a pressure switch 8, a sampling suction pump 9, and the like. A sampling tube 14 having a sampling probe 11 at its tip, a prefilter 12 at its end, and a drain separator 13 at the other end is connected to the outside of the sampling tube 11. Reference numeral 15 is a span gas inlet connected to the sample gas flow channel 10, and 16 is a drain flow channel provided between the drain separator 13 and the exhaust port 19 including a strainer 17, a suction pump 18, and the like.

FIG. 5 schematically shows the configuration of the analysis unit 1. The analysis unit 1 is configured, for example, for single cell multiple component measurement. That is, in this figure, 20 is a cylindrical measuring cell, both ends of which are closed by cell windows 20a 1 and 20b 2 made of an infrared permeable material, and which are connected to the sample gas channel 10 and a sample inlet 20c and an exhaust port. A sample outlet 20d connected to 19 is provided. Reference numeral 21 is an infrared light source provided on one cell window 20a side of the measurement cell 20 for irradiating the measurement cell 20.

Reference numeral 22 denotes a detection unit provided on the other cell window 20b side of the measurement cell 20, which is provided, for example, on a concentric circle for CO ₂ measurement, HC measurement, CO measurement, and comparison (FIG. Then, for convenience, it is composed of four infrared detectors (hereinafter, simply referred to as detectors) 23, 24, 25, 26 and optical choppers 27 arranged in a line. 23F, 24F, 25F, and 26F are optical filters provided on the light receiving sides of the detectors 23 to 26, respectively, and are bandpass filters that pass infrared rays in the characteristic absorption band of only the measurement target component. For example, the optical filter 23F of the CO ₂ measuring detector 23 is a bandpass filter that passes infrared rays in the characteristic absorption band of CO ₂ , and the other optical filters 24F and 25F are also the same. On the other hand, the optical filter 26F of the comparison detector 26 is a bandpass filter that allows infrared rays having a wavelength without an absorption band to pass through the coexisting gas in the sample gas.

The optical chopper 27 is rotationally driven by a motor (not shown), and is configured to chop the infrared light that passes through the measuring cell 20 and is incident on the detectors 23 to 26.

The outputs of the detectors 23 to 26 are respectively input to the microcomputer 4 via a preamplifier. For example, the CO ₂ concentration is calculated from the output of the comparison detector 26 to the output of the CO ₂ measurement detector 23. Is obtained by subtracting.

In order to measure the concentrations of CO ₂ , HC, and CO contained in the exhaust gas of an automobile using the exhaust gas analyzer having the above-mentioned configuration, the sampling probe 11 of the automobile is set in the measurement mode state. Insert into an exhaust pipe (not shown) to sample the exhaust gas. Here, the measurement mode refers to a state in which the sampling pumps 9 and 18, the infrared light source 21, and the motor of the optical chopper 27 are in the ON state, and the sampling can be immediately performed to perform the measurement.

The sampled exhaust gas (hereinafter, referred to as sample gas SG) is introduced into the measurement cell 20 through the sample gas passage 10. The infrared light emitted from the infrared light source 21 and passing through the measuring cell 20 is the infrared light having a wavelength unique to CO ₂ , HC, and CO contained in the sample gas SG introduced into the measuring cell 20. The amount of infrared light that is absorbed and enters the measuring detectors 23 to 25 is reduced. On the other hand, the amount of infrared light incident on the comparison detector 26 does not decrease because it has a wavelength without an absorption band in the sample gas.

Therefore, the concentrations of CO ₂ , HC, and CO can be obtained by subtracting the outputs of the measurement detectors 23 to 25 from the output of the comparison detector 26, respectively, and the detected CO ₂ , HC, and CO concentrations are displayed on the display / external output unit 3.

As described above, the above-mentioned exhaust gas analyzer is extremely easy to handle and has the advantage that it can simultaneously measure the concentrations of a plurality of components to be measured. It is used in vehicle inspection areas.

By the way, in the exhaust gas analyzer of this type, the display unit of the display / external output unit 3 is, for example, an LCD (Liquid Crystal Display) using a liquid crystal. In the past, the backlight of the LCD was kept on even in the standby mode in which the measurement was not performed, and in particular, the backlight was not turned off.

[0016]

[Problems to be solved by the device]

 For this reason, in the conventional exhaust gas analyzer, the backlight of the LCD continues to light up as long as the power is on, and the normal life is about 10,000 hours, which is much shorter than this. There was such an inconvenience.

The present invention has been made in consideration of the above matters. In a standby mode in which measurement is not performed, the backlight of the liquid crystal display unit is turned off so that the backlight of the liquid crystal display unit is turned on. The aim is to provide an infrared gas analyzer that extends the life and promotes energy saving.

[0018]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention is designed to detect a specific measurement target component in a sample gas and display the measurement result on the display unit when the standby mode is maintained for a predetermined time. The feature is that it has a function to turn off the backlight of the liquid crystal display.

[0019]

[Action]

 For example, when the standby mode is entered from a mode other than the standby mode, such as the measurement mode and the calibration mode, the LCD backlight control counter is set for a certain period of time, the countdown is started, and this count value becomes zero. When that happens, turn off the back light on the LCD. By doing this, when the standby mode in which no measurement is performed continues for a certain period of time, the backlight of the LCD is always turned off, the shortening of the life of the LCD is prevented, and energy saving is promoted.

[0020]

【Example】

 FIG. 1 shows a front view of an exhaust gas analyzer as an example of the infrared gas analyzer of the present invention. The display / external output unit 3 is formed on the front side of a housing 5. The display / external output unit 3 is provided with a liquid crystal display unit 28 and an operation unit 29. The liquid crystal display unit 28 is configured so that its display screen is illuminated by a backlight. The liquid crystal display unit 28 displays the analysis result as indicated by reference numeral 30 and the exhaust gas analyzer as currently indicated by reference numerals 31 to 37. It indicates what kind of state (mode) it is in. For example, 31 is "warming up", 32 is "remaining time until calibration", 33 is "zero calibration", 34 is "measuring". , 35 is a "sampling abnormality", 36 is a "filter replacement", and 37 is a symbol mark showing "calibration failure", respectively. Further, the operation unit 29 is provided with a measurement command key 38, a screen switching key 39, a cursor movement / numerical value switching key 40, a function key 41, a brightness adjustment key 42 and the like.

The other components of the exhaust gas analyzer are mechanically and structurally the same as those shown in FIGS. 3 to 5, and in the standby mode where no measurement is performed, the liquid crystal display unit 28 is used. The backlight (hereinafter simply referred to as "backlight") is different from the conventional exhaust gas analyzers of this type in that it is configured to be turned off. Hereinafter, description will be given with reference to the flowchart shown in FIG.

Now, it is assumed that the exhaust gas analyzer is in another mode, for example, the measurement mode (step S1). In this measurement mode, the sampling pumps 9 and 18, the infrared light source 21, the motor of the optical chopper 27, etc. are turned on, and the backlight is turned on.

Then, after the predetermined measurement is completed, the measurement command key 38 is operated, and the exhaust gas analyzer is switched to the standby mode (step S2). Here, the time T of the counter is set (step S3). This time T is set to 10 minutes, for example.

It is determined whether or not there is a key input to shift to a mode other than the standby mode (step S4). If there is a key input, the process proceeds to the YES direction and returns to step S1. Then, if there is no key input, the process proceeds to NO and the countdown of the counter is started (step S5).

Then, it is determined whether or not the count value has become zero (step S6). If not, the process proceeds to NO and returns to step S4. On the other hand, in the case of zero, the process proceeds in the direction of YES and the backlight is turned off (step S7). In other words, it was decided that the standby mode continued for 10 minutes and it was not necessary to keep the backlight on.

When the backlight is to be turned on for some reason while the backlight is off, the back light is turned on by operating the appropriate operation key (YES in step S8) (step S9), and the mode state is set. The backlight can be turned on without changing.

The present invention is not limited to the above embodiment, and it goes without saying that the time T of the counter can be set arbitrarily. Further, the analysis unit 1 does not necessarily have to be configured to measure a plurality of components, and may be configured to be able to measure only a single component to be measured.

The present invention is not limited to the above exhaust gas analyzer but can be widely applied to infrared gas analyzers in general.

[0029]

As described above, according to the present invention, when the standby mode in which the display unit is rarely seen continues for a certain period of time, the backlight is turned off to extend the life of the backlight and analyze it. It is possible to effectively save energy in the total.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a configuration of a front portion of an infrared gas analyzer of the present invention.

FIG. 2 is a diagram showing an example of a flowchart for turning on or off a backlight in the infrared gas analyzer.

FIG. 3 is a diagram schematically showing a configuration of the infrared gas analyzer.

FIG. 4 is a diagram showing a gas flow of the infrared gas analyzer.

FIG. 5 is a diagram schematically showing an example of a configuration of an analysis unit of the infrared gas analyzer.

[Explanation of symbols]

 28 ... Liquid crystal display part, SG ... Sample gas.

Claims (1)

[Scope of utility model registration request] 1. An infrared gas analyzer for detecting a specific component to be measured in a sample gas and displaying a measurement result on a display unit, when a standby mode state continues for a predetermined time, the back of the liquid crystal display unit is backed up. An infrared gas analyzer that has a function to turn off the light.