JP3543210B2 - Waveform observation device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a waveform observing device such as a digital oscilloscope, and more particularly, based on a predetermined range of an output waveform as a reference, displaying the size of a measurement range arbitrarily determined with respect to this reference range, The present invention relates to an apparatus for facilitating observation.
[0002]
[Prior art]
FIG. 4 is a block diagram showing a conventional example of a waveform observation device such as a digital oscilloscope (hereinafter referred to as DSO). In the figure, a measurement signal from a measurement target is output from a sensor amplifier (not shown), and is input to the A / D converter 1 and also to the trigger generation circuit 2 at the same time. When a predetermined trigger condition (such as a predetermined voltage) is satisfied, the trigger generation circuit 2 generates a trigger signal and inputs the signal to the data acquisition control circuit 3.
[0003]
The data fetch control circuit 3 writes the A / D converted digital data into the memory 4 in accordance with the trigger signal from the trigger generation circuit 2. The display control circuit 5 reads the data written in the memory 4, converts the data into display data, and inputs the display data to the display unit 6. The display unit 6 displays the input data as a waveform by a display unit.
[0004]
The cursor control circuit 7 moves the cursor to a specified position on the display unit 6 based on the measurement signal stored in the memory 4. The voltage at the position of the cursor and the time when the voltage is generated are displayed at predetermined positions on the display unit 6.
[0005]
FIG. 5 shows details of the cursor control circuit 7 shown in FIG. The cursor control circuit 7 converts the output from the rotary encoder 8 into time data by the pulse train conversion circuit 9, reads data from the memory 4 based on the time data, converts the data into voltage data, and outputs it to the display unit 6.
[0006]
FIG. 6 shows a conventional DSO in which a rectangular wave is input and the voltage at an arbitrary position is displayed using a pair of cursors. The resolution of the horizontal width of this screen is, for example, 1 × 104 points, the point indicated by (a) is the ground point (zero voltage), and the point indicated by (b) is the trigger point.
[0007]
In FIG. 6, the cursor a is located 10 points away from the trigger point (b), indicating that the voltage at that position is 5.2 V (portion indicated by T1). Cursor b is located 2260 points to the right of the trigger point (b), the voltage at that position is 6 V (the portion indicated by T2), and the point difference (time width) between cursor a and cursor b is 2250 points , The voltage difference is 800 mV (portion indicated by ΔT).
[0008]
[Problems to be solved by the invention]
By the way, there is a case where the ignition timing of, for example, an automobile engine is measured using such a DSO. FIG. 7 is a schematic configuration diagram illustrating a state in which a pressure that changes in association with the movement of the piston 26 in the cylinder 22 of the engine 20 is measured. A measurement sensor (for example, a piezoelectric element) 21 is disposed in the cylinder 22. It is attached to the washer of the spark plug 23, and when the load changes due to the combustion plug pressing the spark plug 23, the charge is input to the sensor amplifier 24 as electric charge.
[0009]
The sensor amplifier 24 converts the electric charge into a voltage and inputs it to the DSO 25. The DSO 25 displays the voltage waveform on the display unit 6 (see FIG. 4).
In order to improve the performance of the engine, it is necessary to burn the air-fuel mixture quickly by increasing the compression ratio or increasing the number of revolutions to advance the ignition timing. However, if an attempt is made to speed up the combustion, knocking will occur and normal operation will not be achieved.
[0010]
Therefore, the air-fuel mixture can be burned most efficiently by detecting the knocking phenomenon and operating it just before knocking occurs. When detecting the knocking phenomenon, the engine rotation pulse is input as an external sample, the pressure in the engine is measured, and the state in the combustion cycle is observed. When measuring knocking, the horizontal axis of the DSO indicates the number of sample clocks, and the vertical axis indicates the pressure.
[0011]
FIG. 8 shows an example of a waveform observed by the DSO. The vertical axis represents voltage (sensor amplifier output), and the horizontal axis represents sampling time or the number of clocks (when an external clock is input). In actual physical quantities, the vertical axis indicates pressure and the horizontal axis indicates crank angle, and the range from the bottom dead center shown in (a) to the next bottom dead center (b) corresponds to -180 ° to 180 °.
[0012]
What is desired to be observed is the crank angle at the time of occurrence of knocking. Therefore, the crank angle is converted from the time or the number of clocks obtained by the DSO cursor measurement into the crank angle by the following equation.
(Number of clocks between cursor measurements / number of clocks in one cycle) × 360 ° (1)
In this calculation, the operator measures a clock corresponding to one cycle in advance, and thereafter calculates the angle by applying the formula (1) by manual calculation every measurement.
[0013]
However, performing the calculation using the formula (1) during the actual measurement is cumbersome, and there is a problem that the calculation result may cause an error in the measurement result.
An object of the present invention is to provide an observation apparatus which facilitates measurement by automatically calculating the formula (1) inside the DSO so that the result of the cursor measurement is directly in the dimension of the object to be measured. It is in.
[0014]
[Problems to be solved by the invention]
In order to achieve such an object, in the present invention,
The output from the measurement target is captured by a clock signal, the output waveform is displayed on a display screen, and a time difference in a predetermined range of the displayed output waveform is specified using a pair of measurement cursors and specified by the pair of measurement cursors. In the waveform observation device that displays the voltage and voltage difference of each part,
A pair of reference cursors for displaying a predetermined range of the output waveform is provided in addition to the pair of measurement cursors, and time data in a range between the measurement cursors is measured based on time data in the range of the pair of reference cursors. A numerical value converted into a target physical quantity is configured to be displayed on the display screen, wherein the clock signal is an external clock, and a predetermined range of a reference cursor is set as one cycle of an output waveform. Features.
The physical quantity to be measured is characterized by using an angle as a unit.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of an embodiment of the present invention in which a reference cursor control circuit 12 is added to the measurement cursor control circuit 7 shown in FIG.
In the figure, a cursor control circuit 7 converts an output from a rotary encoder 8 into time data by a pulse train conversion circuit 9 and sends it to a measurement cursor control circuit 7a or a reference cursor control circuit 12 determined by a selection circuit 10. When the reference cursor control circuit 12 is selected, the time data and the numerical value input from the reference value generating circuit 11 are stored as numerical values in the working memory.
[0016]
In this case, if an output waveform corresponding to the rotation angle of the crank as shown in FIG. 8 is to be measured, one rotation of the crank is set to 360 ° and the angle is set to one cycle to determine the width of the reference cursor. That is, as shown in FIG. 2, the DSO is instructed by using the reference cursor and the numerical value input knob as to where and how many times the measured waveform corresponds.
[0017]
Next, when the measurement cursor control circuit 7 is selected, data is read from the memory 4 based on the time data and converted into voltage data. The measurement cursor control circuit 7a converts the angle data into the angle data by performing the operation of the above formula (1) according to the time data and the reference time data and the reference value held by the reference cursor control circuit 12, and finally converts the voltage data and the angle. Convert data to display data and display it.
[0018]
FIG. 3 shows a pair of reference cursors R1 and R2 fixed at positions corresponding to one cycle of the waveform. When R1 is 0 ° and R2 is 360 °, the measurement cursor M1 is at a position of 726.10 °. This shows that M2 is at a position of 1206.10 °, and that the distance between the measurement cursors M1 and M2 is 480.00 °.
If an output waveform corresponding to the rotation angle of the crank as shown in FIG. 8 is measured, one rotation of the crank is set to 360 ° and the angle is set as one cycle to determine the width of the reference cursors R1 and R2 , If one is placed at a position corresponding to 0 ° in one cycle of the waveform and the other is adjusted to an arbitrary position (for example, a position where knocking occurs), knocking occurs when the crank rotates many times. Can be known without having to do any manual calculations.
[0019]
The foregoing description of the present invention has been presented by way of illustration and example only of particular preferred embodiments. Thus, it will be apparent to one skilled in the art that the present invention may be modified or modified in many ways without departing from its essentials. The scope of the present invention defined by the description of the claims is intended to cover alterations and modifications within the scope.
[0020]
【The invention's effect】
As described above, according to the present invention, a reference cursor for displaying a predetermined range of the output waveform is provided in addition to the pair of measurement cursors, and the range between the measurement cursors is set based on the range of the reference cursor. It was configured to be displayed on the display screen. As a result, an observation device that facilitates measurement can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a cursor control circuit according to the present invention.
FIG. 2 is a diagram showing a relationship between one cycle of a waveform and an angle.
FIG. 3 is a diagram showing a relationship between a reference cursor and a measurement cursor according to the present invention.
FIG. 4 is a block diagram showing a configuration of a conventional waveform observation device.
FIG. 5 is a block diagram illustrating a configuration of a conventional cursor control circuit.
FIG. 6 is a diagram illustrating a relationship between a waveform of a conventional waveform observation device and a measurement cursor. FIG. 7 is a schematic configuration diagram illustrating a state where a pressure in a cylinder of an engine is measured.
FIG. 8 is a diagram showing an example of a waveform observed by the waveform observation device.
[Explanation of symbols]
Reference Signs List 1 A / D converter 2 Trigger generator 3 Data capture control circuit 4 Memory 5 Display control circuit 6 Display unit 7 Cursor control circuit 8 Rotary encoder 9 Pulse train conversion circuit 10 Selection circuit 11 Reference value generation circuit 12 Reference cursor control circuit 20 Engine 21 Sensor (compression element)
22 Cylinder 23 Spark plug 24 Sensor amplifier 25 Waveform observation device (DSO)

Claims (4)

The output from the measurement target is captured by a clock signal, the output waveform is displayed on a display screen, and a time difference in a predetermined range of the displayed output waveform is specified using a pair of measurement cursors and specified by the pair of measurement cursors. In the waveform observation device that displays the voltage and voltage difference of each part,
A pair of reference cursors for displaying a predetermined range of the output waveform is provided in addition to the pair of measurement cursors, and time data in a range between the measurement cursors is measured based on time data in the range of the pair of reference cursors. A waveform observation apparatus, wherein a numerical value converted into a target physical quantity is displayed on the display screen. 2. The waveform observation device according to claim 1, wherein the clock signal is an external clock. 2. The waveform observation device according to claim 1, wherein the predetermined range of the reference cursor is one cycle of the output waveform. The waveform observation device according to claim 1, wherein the physical quantity of the measurement target is in units of angles.

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