JPS62203066A - Apparatus for measuring waveform level - Google Patents

Abstract

PURPOSE:To simplify circuit constitution and to enhance measuring accuracy, by outputting a trigger level, when the time between the fall and rise of an input waveform or the rise and fall thereof coincides wit a set time, as a measuring level. CONSTITUTION:The input signal S1 from an electronic device 6 is counted by a counter circuit 7. A predetermined time setting circuit 11 sets the predetermined time T with respect to the waveform of the existing normal signal S1 to a control/operation circuit 8 and an initial trigger level setting circuit 12 sets an initial trigger level V0 to the circuit 8 and the time t1 between the fall and rise of the signal S1 or the rise and fall thereof is measured at the level V0 by the circuit 7. The time t1 at the level V0 is compared with the time T and the level V0 is altered stepwise until both times coincide. When both times coincide, the level V0 at that time is outputted as a measuring level. By this method, circuit constitution is simplified and measuring accuracy can be enhanced.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is mainly concerned with determining whether an electronic device is a good product or a defective product by determining whether the output waveform of the electronic device is normal or abnormal. The present invention relates to a waveform level measuring device used for inspection, for example, measuring waveforms of VTR morph servo signals, synchronization signals, etc. to determine the quality of its control circuit.

<Conventional technology> A conventional waveform level measuring device of this type is shown in FIG.

In Figure 4, I! , tii child device, 2 is a sample hold circuit, 3 is a timing circuit, 4 is a sunfling pulse generation circuit, and 5 is a sampling time setting circuit.

Next, the operation will be explained based on FIG.

For example, an electronic device l generates a signal Sl having a waveform as shown in the figure.
is output, measure the level v8 of this signal S at time T0, and check whether the cor level V is within the permissible range (±α) of the specified level vR (■, −α≦
A case of determining VX≦VR+α) will be described.

In the sampling time setting circuit 5, a sampling time T0 is set in advance.

A signal S output from the electronic device 1 is input to a sample hold circuit 2 and a timing circuit 3. The timing circuit 3 generates three timing pulses at the rising and falling timings of the input signal S+. This timing pulse S2 is output to the sampling pulse generation circuit 4.

The sampling pulse generation circuit 4 outputs the sampling pulse S to the sample hold circuit 2 based on the input timing pulse S2 and the sampling time T0 set by the sampling time setting circuit 5.

The sample hold circuit 2 receives this sampling pulse S.
The signal SI input from the electronic device 1 is sampled within the input time T0 of No. 3.

The level of this sampled signal S is 8.

Then, the signal of the level vX measured in this way is output to a judgment circuit (not shown), and the above-mentioned ■7-α≦■8≦
Determine V, l+α.

<Problems to be Solved by the Invention> However, the conventional example having such a configuration has the following problems.

(a) As a circuit configuration of the waveform level measuring device, a sample hold circuit dedicated to the output waveform of each measurement device 2. Timing circuit 3. Sampling pulse generation circuit 4. A sampling time setting circuit 5 is required, making the entire circuit complicated and expensive.

(b) Timing pulse S2 and sampling pulse S,
synchronization with sampling pulse s3 and input signal S
It is difficult to synchronize with I, and there is a risk that a synchronization error may result in outputting the signal S4 at an incorrect level. In particular, the signal s
When the time T0 to be measured in 1 is short or the waveform of the signal S1 is complex, a shift occurs in the period T0 to be measured, making measurement impossible.

<Objective of the Invention> An object of the present invention is to solve these problems of the conventional example, simplify the circuit configuration, and improve measurement accuracy.

<Means for Solving the Problems> In order to achieve the above object, the present invention has the following configuration.

That is, the waveform level measuring device of the present invention includes: a means for setting a predetermined time including the level to be measured of the input waveform; a means for setting a trigger level for the input waveform; - means for measuring the time between falling edges; means for comparing the time measured by the time measuring means with a predetermined time set by the predetermined time setting means; and stepwise adjusting the trigger level until these two times match. The apparatus includes a trigger level slight change means for making a slight change, and a measurement level output means for outputting the trigger level at that time as a measurement level when the two times coincide with each other by the time comparison means.

In this configuration, the "predetermined time period including the measurement target level of the input waveform" refers to the falling and rising edges of the regular input waveform at a level slightly displaced from the measurement target level on the opposite side of the initial trigger level with respect to the measurement target level. It is the time between the rise and fall.

<Effect> The effects of this configuration are as follows.

(i) In advance, the predetermined time setting means sets a predetermined time including the level to be measured of the input waveform, and the trigger level setting means sets an initial trigger level.

The time measuring means measures the time between falling and rising edges or between rising and falling edges of the input waveform at the initial trigger level. The time comparing means compares the measurement time at the initial trigger level measured by the time measuring means and the predetermined time set by the predetermined time setting means.

As a result of this comparison, if the two times do not match, the trigger level slight change means minutely changes the trigger level by one step.
Set it as a small change trigger level.

The time measuring means measures the time between falling and rising edges or between rising and falling edges of the input waveform again at the first minute change trigger level. The time comparing means compares the measurement time at the first minute change trigger level measured by the time measuring means and the predetermined time set by the predetermined time setting means.

As a result of this comparison, if the two times do not match, the trigger level fine change means further finely changes the trigger level by one step to obtain a second finely changed trigger level.

In this way, the trigger level slight change means minutely changes the trigger level step by step until the predetermined time and the measurement time match.

The measurement level output means outputs the trigger level at that time as the measurement level when the time comparison means determines that the predetermined time and the measurement time match.

The trigger level at which the predetermined time and the measurement time match may be the initial trigger level, or may be a trigger level that has been slightly changed in one step or over multiple steps.

Ni) In the conventional example, it is necessary to decide whether to output or stop the sampling pulse at strict timing.
However, in the case of the present invention, the level to be measured is measured based on changes in the trigger level, and timing processing is not required. Therefore, the overall circuit configuration can be simplified.

(iii) For the same reason as (ii) above, erroneous measurements caused by synchronization errors that occur in the conventional example are eliminated.

Furthermore, the measurement accuracy is not affected by the short time required to measure the level of the measurement target or by the complexity of the input waveform.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block circuit diagram of a waveform level measuring device according to an embodiment of the present invention.

In FIG. 1, 6 is an electronic device, 7 is a counter circuit that counts the input signal S1 from the electronic device 6, and 8
9 is the am/arithmetic circuit that controls the overall control and calculations, and 9 is the control/arithmetic circuit.
The trigger level signal S outputted from the arithmetic circuit 8 is connected to D/
10 is a D/A conversion circuit which converts A and outputs the analog signal S to a counter circuit 7;

This is an A/D conversion circuit that A/D converts an analog signal S indicating a measurement time t measured in response to a trigger level signal Ss and outputs the digital signal Ss to a control/operation γ circuit 8. .

11 is the measurement target level ■ in the waveform of the input signal S1.

It is a setting circuit for a predetermined time T including
It is connected to the. Here, the "predetermined time T including the measurement target level ■." refers to the measurement target level ■. ■ Regarding the initial trigger level. The time between the falling and rising edges of a known regular input waveform (in the case of the waveform in Figure 3 (A)) or the rising and falling times at a level displaced by a minute level from the measurement target level V on the opposite side. The time between (Figure 3 (
In the case of waveform B).

This predetermined time setting circuit 11 corresponds to "setting means for a predetermined time including the measurement target level of the input waveform" in the configuration of the invention.

12 is a circuit for setting an initial trigger level v0 for the waveform of the input signal Sl, and is connected to the control/arithmetic circuit 8. This initial trigger level setting circuit 12 corresponds to "trigger level setting means for input waveform" in the configuration of the invention.

Next, the operation of this embodiment will be explained based on the flowchart of FIG. 2 and the waveform diagram of FIG. 3(A).

In step #l, the predetermined time setting circuit 11 sets a predetermined time T for the waveform of the known regular input signal SI, and sets this to the register RT in the control/arithmetic circuit 8.
(RT-T).

In step #2, the initial trigger level setting circuit 12 sets the initial trigger level V. and control this.
Store in register RTL in arithmetic circuit 8 (R
TL-■. ).

For Ste Knob #3, the initial trigger level ■. , the time t1 between the falling and rising edges of the input signal S1 is measured. That is, the initial trigger level signal S is output from the control/arithmetic circuit 8 to the D/A conversion circuit 9. The D/A conversion circuit 9 converts this initial trigger level signal S into an analog signal Sh and outputs it to the counter circuit 7. The counter circuit 7 receives an initial trigger level (2) specified by the analog signal S. , the time t1 between the falling and rising edges of the input signal S1 is measured. In the case of FIG. 3(A), t
+"0. The analog signal S7 indicating the measured time t1 (-0) is converted into a digital signal S6 by the A/D conversion circuit 10 and input to the control/arithmetic circuit 8.

This step #3 is between the falling and rising edges of the input waveform at the trigger level (or between the rising and rising edges) in the configuration of the invention.
This corresponds to "Measurement means for measuring the time (between falling edges)".

In step #4, the initial trigger level ■. The measured time t in , and the predetermined time T stored in the register R7 are compared to determine whether t,=T.

This step #4 corresponds to "comparison means for comparing the time measured by the time measuring means and the predetermined time set by the predetermined time setting means" in the configuration of the invention.

If the initial trigger level is V0, select NO at step #4.
Therefore, move to step #5 and increase the trigger level. That is, the initial trigger level ■ stored in register RTL. Add the minute level ΔV to and set the total value as the first minute change trigger level (■.+
Δ■) in the register RTL (Ry L
= V o +ΔV).

This step #5 corresponds to the "trigger level fine change means for changing the trigger level minutely step by step until the measurement time and the predetermined time match" as referred to in the configuration of the invention.

Next, in step #6, it is determined whether the first slight change trigger level (■.10Δ■) stored in the register RTL is less than or equal to the maximum value V may of the waveform of the input signal SI to be rejected. In the case of FIG. 3(A), the determination is YES and the process returns to step #3.

In this step #3, the first minute change trigger level (■
. +ΔV), the time t2 between the falling and rising edges of the input signal Sl is measured in the same manner as described above. In the case of FIG. 3(A), since Q<t2<T, the next step #4 is again determined as No, and the process moves to step #5.

In this step #5, the trigger level is carried up again. That is, the minute level ΔV is added to the first minute change trigger level (V O + Δ■) stored in the register RTL, and the total value is set as the second minute change trigger level (V
o+2・Δ■) in register RTL (R
rt=Vo"2'Δ■).

Next, through step #6, in step #3, the time t between the falling and rising edges of the input signal S is measured based on the second minute change trigger level (vo+2·ΔV) in the same way as described above. In the case of FIG. 3 (Δ), 1. =t2<"1"
Therefore, in the next step #4, the determination is No again, and the process moves to step #5.

In this step #5, the trigger level is carried up again. That is, the minute level ΔV is changed to the second minute change trigger level (V, +2・Δ■) stored in the register RTL.
, and the total value is set as the third minute change trigger level (
V6+3・Δ■) as register R? Store in L (
RTL-■. +3・Δ■).

Next, through step #6, in step #3, the time L4 between the fall and rise of the input signal S is measured based on the third minute change trigger level (V, +3·ΔV) in the same manner as described above. In the case of FIG. 3(A), since t,='r, it is judged as YES in the next step #4, and step #4 is determined as YES.
Move to 7.

In step #7, the third minute change trigger level (■.+3·Δ■) stored in the register Rtt is set to the actual measurement level ■. ■This actual measurement level is assumed and written to memory. After outputting the data to the outside, the flow ends.

This step #7 is based on the "measurement level output means for outputting the trigger level at that time as the measurement level when the measurement time and the predetermined time match by the time comparison means" in the constitution of the invention. In some cases, the content of the register RTL may be the maximum value V r as determined in step #6.
It may exceed aax. In that case, immediately end the flow.

Note that the waveform of the input signal S from the electronic device 6 is the third waveform.
In the case as shown in FIG. 3B, the initial trigger level v0 is high, and the change in the minute level Δ■ for each step is on the negative side. That is, ■. −Δ■.

By the way, in the judgment at step #4, register R
The trigger level stored in O does not match the measurement target level V, and may be higher than the measurement target level V.

However, if the minute level Δ■ is set to be less than or equal to the allowable range α for determining the quality of the electronic device 6 (Δ■≦α), the determination of the quality of the electronic device 6 will not be mistaken even if there is a discrepancy.

Further, when the determination in step #4 is YES for the first time, the trigger level stored in the register RTL is the measurement target level ■. , the minute level to be changed is set to a minute level ΔV that is even smaller than the first minute level ΔV, and the register R? This time, the same cycle is repeated while subtracting the minute level Δ■, from the contents of L, step by step, and then the judgment in step #4 is N.
o, the minute level to be changed is set to minute level Δ■2, which is even smaller than the previous minute level Δv1,
If the configuration is configured to repeat the same cycle while adding in steps again, the final result will be register R? The trigger level at which the L-strike has been completed and the measurement target level VII will match. Therefore, it is possible to highly accurately determine whether the electronic device 6 is good or bad.

<Efficacy of invention According to the present invention, the following effects are achieved.

(a) Since the level to be measured is measured based on a change in the trigger level, there is no need for severe timing processing as in the conventional example, and the overall circuit configuration can be simplified.

(b) For the same reasons as in (a) above, it is possible to eliminate erroneous measurements caused by synchronization errors that occurred in the conventional example, and the time to measure the level of the measurement target is short and the input waveform is complex. Even if there is a problem, highly accurate measurements can be performed without being affected by it.

[Brief explanation of drawings]

1 to 3 relate to embodiments of the present invention, in which FIG. 1 is a block circuit diagram of a waveform level measuring device, FIG. 2 is a flowchart, and FIG. 3 is a waveform diagram. 4 and 5 relate to a conventional example, in which FIG. 4 is a block circuit diagram of a waveform level measuring device, and FIG. 5 is a waveform diagram. 8...Control/arithmetic circuit

Claims (1)

[Claims] (1) means for setting a predetermined time including the level to be measured of the input waveform; means for setting a trigger level for the input waveform; and measuring the time between falling and rising edges or between rising and falling edges of the input waveform at the trigger level. means for comparing the time measured by the time measuring means with the predetermined time set by the predetermined time setting means; and trigger level fine changing means for slightly changing the trigger level step by step until these two times match. and measurement level output means for outputting a trigger level at that time as a measurement level when the two times match by the time comparison means.