JP3284142B2 - Waveform recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform recorder, and more particularly, to a waveform recorder capable of displaying waveform data with an offset.

[0002]

2. Description of the Related Art When an input waveform is displayed on a display or a printer, an offset voltage is applied to the input waveform to determine the display position (0 position) based on the screen width, recording paper width, or the input waveform of another channel. ) Can be moved arbitrarily.

One example will be described with reference to FIG. 5. In this conventional example, a predetermined offset voltage is generated by an offset control unit via an offset voltage generation unit, and the offset voltage is added to an input signal Vin. ,
A / D conversion is performed and stored in the memory. FIG.
2 illustrates a state in which an offset voltage is added to the input signal Vin.

[0004]

According to this, the display position of the input signal can be arbitrarily shifted in the amplitude direction according to the value of the offset voltage. However, in this method, the offset voltage is included in the A / D conversion data. Therefore, the offset voltage cannot be changed after A / D conversion.

[0005] This means that, for example, when displaying (printing) a multi-channel waveform, if some of the waveforms overlap each other, they are separated unless the offset voltage is changed again and the waveform data is taken in. The disadvantage is that it cannot be performed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has a structural feature that a bipolar input or an offset voltage equivalent to 1/2 of a convertible voltage width is superimposed. A to A / D convert input voltage
An A / D converter, a display unit for displaying an input waveform with 1/2 of the A / D convertible voltage width being a display width in the vertical axis direction, and a 1/2 of the convertible voltage width of the A / D converter. Is displayed on the display unit as a measurable input voltage range of the waveform recorder.
(ACrms) Input allowable voltage setting unit to be displayed, and A
Scrolling means for displaying, on the display unit, waveform data of a section corresponding to an arbitrary continuous half width from LSB to MSB of the / D-converted waveform data, and display magnification changing means; A / A
It is to delete the LSB of the D-converted m-bit waveform data and convert it to m-1 bit data, and display the m-1 bit waveform data in the display unit.

[0007]

[0008]

As described above, for example, the offset voltage is set to A
The display (printing) width is set to 1/2 of the full scale of A / D conversion while the display position is scrolled to 1/2 of the full scale (convertible voltage width) of / D conversion, so that the display position is scrolled. Will be displayed (printed) as if changed. Therefore, the offset position can be changed even after the acquisition of the waveform data.

Further, since m-bit waveform data is converted to m-1 bit waveform data, and the waveform data is compressed by half in the vertical axis direction, the input waveform of the input waveform is increased without increasing the input allowable voltage value. The entire amplitude direction can be displayed on the display unit.

[0010]

Embodiments of the present invention will be described below. FIG. 1 schematically shows a block diagram of the embodiment, according to which the waveform recorder includes an attenuator 11 for attenuating an input signal Vin to an appropriate level, and an attenuator 11 for attenuating the input signal Vin. Adder 1 for adding offset voltage Vref
2 and an amplifier 13 for amplifying the added signal, and an A / D converter 1 for converting the input signal Vin into digital data.
4 is provided.

In this case, as shown in FIG. 2, the A / D converter 14 fixes the offset voltage Vref to の of the convertible voltage width of the A / D converter 14, and sets the input signal Vin to A / D.
A / D converter for / D conversion (in the case of 12-bit A / D,
Vref = 2048 equivalent value) or bipolar type A
Either a / D converter, that is, an A / D converter that can input +/- and sets the A / D conversion value 0H to -1 / 2V and the conversion value FH to + 1 / 2V is used.

In the case of the bipolar type, the input signal V
It is not necessary to add the offset voltage Vref to in. According to the A / D converter 14, the waveform data is A / D converted without applying an offset voltage.

The waveform data A / D converted by the A / D converter 14 is sent to a CPU (Central Processing Unit).
The data is taken into a memory (RAM) 16 according to the control of 15. This waveform data is stored in a printer 17 as a display unit.
In this waveform recorder, a display magnification changing unit 19 for generating a compressed signal of waveform data at the time of display and an offset control unit for scrolling a display waveform in a vertical axis (voltage axis) direction are displayed. 20.

Further, in the present invention, when displaying (or printing) the waveform, the display width in the vertical axis (voltage axis) direction of the display unit is set to 1 / (the A / D convertible voltage width).
2, the offset control unit 20 allows the waveform position of the display unit to be changed within the full scale of A / D conversion, so that the offset can be arbitrarily changed even after the acquisition of the waveform data. It is possible.

Although not shown, in relation to the display width of the display unit, the allowable input voltage is M × V based on the number M of divisions (DIV) on the vertical axis and the voltage value V per 1 DIV. Is set. This corresponds to the input allowable voltage setting unit, and the display is performed by DC (ACrms) of direct current.

FIG. 2 shows the relationship between the input signal Vin and the offset voltage Vref (4096/2 = 2048 in this case) and the relationship between the display waveform and the display screen DISP of the display unit in the case of 12-bit data. It is illustrated, and 0 to 100%
The waveform can be scrolled with any offset between them.

That is, in response to the offset signal from the offset control unit 20, one-half of an arbitrary continuous A / D convertible voltage width from the LSB (least significant bit) to the MSB (most significant bit) of the waveform data is received. The waveform data of the section corresponding to the width is displayed on the display screen DISP.

The right side of FIG. 2 shows a display example (A) of 100% offset, a display example of 50% offset (B) and a display example of 0% offset (C) when the waveform data is not compressed. Thus, a display as if the offset were changed can be obtained.

In FIG. 1, the display screen DISP is moved with respect to the display waveform for the sake of drawing. However, this is a relative problem, and the display waveform is actually scrolled. In this example, the display screen DISP is described as a display unit, but the same applies to printing by a printer.

Incidentally, the allowable input voltage is D as described above.
The product M × V of the number of IVs M and the voltage value V per 1 DIV
Is displayed on the display screen DISP as DC (AC
rms) is displayed, but at the time of AC AC measurement, there are more requests for waveform observation than for the effective value level measurement.
The peak-to-peak voltage width in the C waveform observation is 2 × 2 ^1/2 times the effective value.

Therefore, when a voltage measurement of 2 × 2 ^1/2 times is performed in the DC display, the display of the range and the like is also changed to 2 × 2 ^1/2.
It is necessary to display a voltage of × 2 ^1/2 times, but if such a voltage display is used, safety measures such as a drastic improvement in insulation corresponding to the voltage display are required. However, the AC voltage should be designed with safety such as insulation at its effective value voltage, and in practice, excessive safety design is forced.

For example, when the input allowable voltage of 1/2 scale of the A / D convertible voltage value is set to 500 V (DC or ACr
ms), the safety design of the waveform recorder itself is up to 5
It suffices that this be done for a 00V input. Considering the case of taking in a 240V AC waveform for example under this design, there is no problem since the input itself is less than the input allowable value. Is 240V × 2 × 2
^1/2 = 679 span is required, and 50
It will be out of the 0V span. In addition, the input allowable voltage must be 679 V or more, which imposes an excessive burden on the safety design and only a part of the waveform is displayed, so that the entire waveform cannot be seen at a glance.

Therefore, in the present invention, the LSB (least significant bit) of the waveform data is deleted by turning on the key of the display magnification changing unit 19, for example, and the waveform is reduced to 1 /
2 compression. For example, if the A / D-converted waveform data is 12 bits, the waveform data is converted to 11 bits, and the amplitude of the waveform data is compressed to 1/2 as shown in FIG. .

Therefore, as shown in FIG. 4, the entire waveform is contained in the display screen DISP (or the width of the recording paper), and the waveform can be observed at a glance. This state is equivalent to a display state of 50% offset,
By changing the offset value by the offset control unit 20, the waveform can be scrolled arbitrarily. FIG. 4 illustrates a state where the offset is 10% and the offset is 90%.

[0025]

As described above, according to the present invention, even after the waveform data is stored in the memory, the offset of the waveform can be arbitrarily changed. Also,
Since the waveform data can be compressed and displayed in half, the entire waveform can be displayed within the input allowable voltage range, particularly when the AC waveform is observed.

Therefore, the entire waveform can be grasped at a glance, and it is not necessary to further raise the safety design level.

[Brief description of the drawings]

FIG. 1 is a block diagram according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an input waveform, an offset voltage, and a scroll state of the input waveform according to the embodiment.

FIG. 3 is an explanatory diagram of a state where an input waveform is compressed.

FIG. 4 is a schematic diagram showing a display example of a compressed waveform.

FIG. 5 is a block diagram according to a conventional example.

FIG. 6 is an explanatory diagram for explaining a state of addition of an offset voltage in the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Attenuator 12 Adder 14 A / D converter 15 CPU 16 Memory 17 Printer 18 Display 19 Data compression unit 20 Offset control unit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Zenichi Suzuki 81, Sakuramachi, Koizumi, Ueda-shi, Nagano Prefecture Inside of Hioki Electric Co., Ltd. JP-A-1-299470 (JP, A) JP-A-2-129555 (JP, A) JP-A-61-193378 (JP, U) JP-A-4-16371 (JP, A) U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01R 13/00-13/42

Claims (1)

(57) [Claims] 1. A and A / D converter input voltage obtained by superimposing an offset voltage corresponding to a half of the bipolar input or convertible voltage range to convert A / D, the A / D convertible electrostatic
Displays the input waveform with 1/2 of the pressure width as the display width in the vertical axis direction
Display part to be converted, and one of the convertible voltage widths of the A / D converter.
/ 2 as the measurable input voltage range of the waveform recorder
Input allowable voltage to be displayed in DC (ACrms) on the display unit
A setting unit, scrolling means for displaying waveform data in a section corresponding to an arbitrary continuous 1/2 width from LSB to MSB of the A / D-converted waveform data on the display unit, and display magnification changing means; The display magnification changing means.
As a result, the A / D-converted m-bit waveform data
The LSB is deleted and converted to m-1 bit data.
A waveform recorder for displaying 1-bit waveform data in the display section .