JPH0519774Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] This invention relates to a waveform recorder, and more specifically, to a waveform recorder equipped with a monitor circuit that monitors the input level of a signal under test.

[Technical background of the invention] When recording the waveform of a signal under test using a waveform recorder, etc., as a preparatory step, first turn off the input of the signal under test, and in that state set the starting position of the waveform recording head. In other words, we are trying to find out where the zero point is on the recording paper. The reason for this is that if the waveform of the signal under test is expected to be approximately symmetrical vertically, the zero point will be set near the center of the recording paper, but if the signal waveform is expected to be convex upward, the zero point will be set downward. On the other hand, if the zero point is expected to be concave downward, it is necessary to move the zero point upward. In this case, the zero point position is generally adjusted vertically by running the recording paper to draw a zero line, but this is not preferable because the recording paper is wasted.

Furthermore, if the waveform is no longer drawn during waveform recording, it is necessary to check whether the signal under measurement is being input. However, when performing outdoor measurement work, etc., it is not always possible to carry such check measuring instruments with you, so it is recommended to have a waveform recorder that can easily check the presence or absence of input signals and the zero point position when there is no signal. It was wanted.

[Purpose of the invention] This invention was made in response to the above-mentioned demand, and its purpose is to convert the measured signal output from the A/D converter into a plurality of light emitting units arranged in a line via a decoder. A waveform recorder that has a monitor circuit that makes it possible to determine the zero point position of the recording head, the presence or absence of an input signal, and the magnitude of the signal level by lighting a light emitting element at a position corresponding to the magnitude of the level. The objective is to provide a measurement system.

[Examples] This invention will be explained in more detail below with reference to embodiments shown in the accompanying drawings.

Referring to FIG. 1, the waveform recorder shown in this embodiment includes, for example, a signal input section 1 and a recorder main body 2. As shown in FIG.

Each part will be explained below. A signal under test from the signal source 3 is first applied to, for example, a preamplifier 4 in the signal input part 1. This preamplifier 4 has amplification characteristics with good linearity, and also serves as a buffer amplifier, and the applied signal under test is appropriately amplified here, and is used as an A/D converter 5 in the next stage.
sent to.

In this embodiment, the A/D converter 5 is of an 8-bit successive approximation type, and the input signal from the preamplifier 4 is
This A/D converter 5 converts it into an 8-bit digital signal. The photocoupler 6 is provided to cut off the induced voltage to the ground superimposed on the input signal, and is made up of eight light-emitting photodiodes 7 and eight light-emitting phototransistors 8 paired with these. The 8-bit digital signal output from the A/D converter 5 is applied to each of the eight photodiodes 7. As a result, a photoelectrically converted digital signal containing no induced voltage is emitted from the phototransistor 8, and is input to the measuring section 9 of the recorder main body 2. This input signal causes the measuring section 9 to record the waveform of the signal to be measured.

The main body 2 of the waveform recorder according to this invention includes, in addition to the measuring section 9, a decoder circuit 10 and a display 11.
An input signal monitor circuit 12 is provided, and the photoelectric conversion signal generated from the phototransistor 8 is also input to this decoder circuit 10.

That is, among the 8-bit signals from MSB to LSB sent from the eight phototransistors 8, for example, the signals of the MSB, bits 2, and 3 of the upper three bits are branched and input to the decoder circuit 10. It's becoming like that. Decoder circuit 10
With these three signals, the signal changes from "1, 1, 1" to "0, 1," depending on the input level of the signal under test.
Eight types of signals are formed up to "0, 0". In other words, when one range is divided into eight sections from zero to full scale, the level of each section can be made to correspond to one of the top eight types of bit signals. Of course, if you want to make the corresponding section even finer, you can increase the number of bits, and if you want to make it coarser, you can decrease the number of bits.

These eight types of signals are amplified by an amplifier circuit in the decoder circuit 10, and are then amplified by, for example, eight light emitting diodes 13 to 2 arranged in a line on the display 11.
0 in the order of signal level magnitude. Thereby, the input level of the signal to be measured can be displayed in eight stages by lighting the light emitting diodes 13 to 20 of the display 11. Among these light emitting diodes, for example, when the light emitting diode 20 is lit, the input level is in the maximum level range including full scale, and when the light emitting diode 13 is lit, the input level of the signal under measurement is Needless to say, this is when the range is at the minimum level including zero.

In the above embodiment, if the zero point of the waveform recording head is to be set, for example, at approximately the center of the recording paper, the input of the signal to be measured is turned off, that is, the light emitting diode 13 is lit. After this, an offset voltage is applied to a recording head drive circuit (not shown) in the measuring section 9 and an amplifier circuit (not shown) in the decoder circuit 10, respectively. In this case, if you move the lighting of the light emitting diodes in the display 11 from 13 to 14 and 15 and adjust the offset voltage so that, for example, 16 or 17 lights up, the zero point position of the recording head will be approximately at the center of the recording paper. This means that it is set to . The same procedure as above may be used when moving the zero point to another position.

FIG. 2 shows a signal input section 1a and a recorder main body 2a.
An embodiment is shown in which the photocoupler 6a is simplified by using a parallel/serial conversion circuit 21 and a serial/parallel conversion circuit 22, respectively. The other circuit configurations are similar to those of the embodiment shown in FIG. 1 above, so the same reference numerals are given.

In FIG. 2, a signal under test from a signal source 3 is applied to a parallel/serial conversion circuit 21 via a preamplifier 4 and an A/D converter 5. Here, the 8-bit parallel signal from the A/D converter 5 is converted into an 8-bit serial signal, which is outputted sequentially from MSB to bit 2, bit 3, . added to. Therefore, unlike the photocoupler 6 shown in FIG. 1, this photocoupler 6a is composed of a pair of a light-emitting photodiode 7a and a light-receiving phototransistor 8a. The signal to be measured is photoelectrically converted via this phototransistor 8a, and transferred in time series to a serial/parallel conversion circuit 22 provided within the recorder main body 2a.

In the recorder main body 2a, the 8-bit signal sent in time series is inversely converted into a parallel signal by the serial/parallel conversion circuit 22, and the following is the same as in the embodiment shown in FIG. 1 above. At the same time, all bit signals are sent to the measuring section 9, and among them,
The upper 3 bit signals for display are sent to the decoder circuit 10.
It is also now being sent to

Regarding the parallel/serial conversion circuit 21 and the serial/parallel conversion circuit 22, IC chip elements are easily available, so if these are used, the photocoupler 6a is simplified, and the signal input section 1
The signal transfer cable from a to the recorder main body 2a is also simplified. Therefore, this embodiment is particularly suitable for downsizing the signal input section 1a.

FIG. 3 shows an embodiment of a multi-channel waveform recorder. Three signal sources 3a, 3b,
A signal input section 1a configured similarly to the signal input section 1a shown in FIG. 2 above is connected to each of the terminals 3c. The recording main body 2b is provided with a channel selection circuit 23 and a controller 24 that issues a command signal for its switching operation. A serial/parallel conversion circuit 22, a measuring section 9, a decoder circuit 10, configured in the same manner as the recorder main body 2a,
A display 11 is provided. The signal source 3a,
The signals to be measured having different waveforms emitted from the recorders 3b and 3c are respectively input to the recorder main body 2b through the respective signal input sections 1a. Among these input signals, a desired one channel signal is extracted via the channel selection circuit 23 according to a command signal from the controller 24, and the signal of the desired one channel is extracted from the signal to be measured, as in the case of the embodiment shown in FIG. The signal waveform is recorded and the signal level is displayed.

[Effects of the invention] As explained above, according to this invention, the MSB in the signal obtained by digitally converting the signal under test
By receiving the upper n bits of the signal including The zero point position of the recording head, the presence or absence of an input signal, and the magnitude of the signal level can be displayed with a simple and inexpensive configuration.

Furthermore, since the digital signal is insulated from the induced voltage from the ground via a photocoupler, it is extremely safe against electric shocks caused by potential differences with the ground during device operation.

[Brief explanation of the drawing]

The attached drawings all relate to embodiments of the waveform recorder according to this invention, and Fig. 1 is a block diagram when this invention is applied to a one-channel waveform recorder, and Fig. 2 is a diagram showing the waveform recorder shown in Fig. 1 above. FIG. 3 is a block diagram showing a modified embodiment of the waveform recorder according to the present invention. FIG. 3 is a block diagram when the modified embodiment shown in FIG. 2 is applied to a multi-channel waveform recorder. In the figure, 1, 1a are signal input parts, 2, 2a, 2b
is the recorder body, 5 is the A/D converter, 6, 6a
is a photocoupler, 9 is a measuring section, 10 is a decoder, 1
1 is a display, and 13 to 20 are light emitting diodes.

Claims (1)

[Claims for Utility Model Registration] Measurement that includes an A/D converter that converts a signal under measurement emitted from a signal source into a digital value, and a recording head that photoelectrically converts the output of the A/D converter and uses it as a waveform recording signal. In a waveform recorder comprising a signal conversion section consisting of a photocoupler, the MSB in the signal output from the signal conversion section is
a decoder circuit that receives a signal of the upper n bits including the above signal and forms one lighting signal corresponding to the level of the signal under test from among 2 ⁿ signals that can be formed; The range from '' to the maximum level is divided into ²ⁿ sections, and ²ⁿ light emitting elements are arranged in order of high and low levels corresponding to each section.The signal under test is detected by the lighting signal from the decoder circuit. A waveform recorder comprising: an indicator in which one light emitting element corresponding to an input level is lit.