JP2856667B2 - Differential circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal detection circuit such as a CCD sensor for a sun sensor, which is used to generate a PID control signal from a detection signal periodically. It relates to a differential circuit to be extracted.

[0002]

2. Description of the Related Art Generally, a PI for generating a PID control signal is used.
As shown in FIG. 3, the D control circuit guides a detection signal S (n) periodically sampled by a digital detection circuit 10 such as a CCD sensor to a proportional circuit 11, an integrating circuit 12, and a differentiating circuit 13, and (P), integration (I) and differentiation (D), and a proportional signal K · Sn, an integration signal Sn and a differential signal {S (n) −S (n−1)} / Δ for speed compensation.
After generating T × X (n), adder 14 adds PI
D control signal is obtained. In this case, as the differentiating circuit 13, the difference circuit 13a calculates the temporal difference signal S (n) -S (n-1) for each sampling from the detection signal S (n), and then calculates the difference by the divider 13b. And the difference signal S (n) -S
The differential signal {S (n) −S (n−1)} / ΔT × X (n) is obtained by dividing the sampling period ΔT from (n−1) and multiplying by the speed compensation gain in the speed compensation circuit 13c. I have.

FIG. 4 shows such a conventional difference circuit. A detection signal S (n) (indicated by a solid line in FIG. 4) periodically sampled by a detection circuit 10 is supplied to an analog delay line 1 for a predetermined period ΔT. A delay signal S (n-1) (indicated by a broken line in FIG. 5A) is generated. Then, the delay signal S (n-1) is guided to the difference amplifier 2 together with the detection signal S (n), and the difference is extracted, and the difference signal S (n)-as shown in FIG. S (n-1) is generated.

However, in the above-mentioned differential circuit, since the configuration using the differential amplifier 2 having a complicated configuration is complicated and large, the electronic circuit is required to have a particularly strict space requirement for space-borne equipment and the like. There was a problem that it was unsuitable for application to equipment.

[0005] In addition, although there is a type provided with a sample-and-hold circuit (not shown) instead of the analog delay line 1, a difference amplifier must be provided similarly.
Have similar problems.

[0006]

As described above, the conventional difference circuit has a problem that the structure is complicated and large in size because a complicated difference amplifier must be provided. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a differential circuit which can realize accurate extraction of a temporal difference, and which can be simplified and simplified in configuration. I do.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a differential circuit for extracting a difference signal between the present time and one sample before a detection signal periodically sampled by a detection circuit.
A differentiating circuit for obtaining a signal having a differentiated waveform by differentiating the detection signal obtained by the detecting circuit; and holding the peak value of the signal obtained by the differentiating circuit for one sampling period to perform one sampling.
And a sample-and-hold circuit for generating a difference signal from the peak value of the signal before the cycle .

[0008]

According to the above construction, the differential signal is converted into a signal having a differentiated waveform obtained by differentiating the detection signal by the differentiating circuit, and the peak value of the signal is sampled by the sample-and-hold circuit for one sampling period. Obtained by holding. Therefore, since it is not necessary to provide a differential amplifier having a complicated configuration, the configuration can be simplified and the size can be reduced.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a differential circuit according to an embodiment of the present invention. For example, the differential circuit 1 shown in FIG.
3 corresponds to the difference circuit 13a. That is, C
A differentiating circuit 20 is connected to the output terminal of the detecting circuit 10 such as a CD sensor.
Is connected. The differentiating circuit 20 is formed by a capacitor C and a resistor R, and an output terminal thereof is connected to a sample hold (S / H) circuit 21 connected to the divider 13b (see FIG. 3).

With the above configuration, the detection signal S (n) (see FIG. 2A) periodically sampled by the detection circuit 10 is guided to the differentiating circuit 20 and differentiated, as shown in FIG. 2B. Is converted into a pulse-like signal having a differential waveform. This pulse signal has its peak value (l ₁ , l ₂ ,
l ₃ , l ₄ ) is the detection signal S (n−1) one sample before.
, And is led from the differentiating circuit 20 to the S / H circuit 21 at a change point of the detection signal S (n). The S / H circuit 21 samples at the peak value of the differential waveform, and then holds the signal for a certain period of time ΔT to obtain a difference signal S (n) −S (n−1) as shown in FIG. And the divider 13
b (see FIG. 3), and the differential signal ｛S
(N) −S (n−1)} / ΔT × (n) is generated.

As described above, the above-mentioned difference circuit is composed of the detection circuit 1
The detection signal of 0 is differentiated by the differentiating circuit 20 to be converted into a peak signal having a differentiated waveform, and the peak value of the peak signal is held by the S / H circuit 21 for one sampling period. Since the configuration is such that the differential signal is obtained, it is not necessary to provide the differential amplifier 2 (see FIG. 4) having a complicated configuration as in the related art, so that the configuration is simplified and the size is reduced as much as possible. Can be achieved. It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0012]

As described above in detail, according to the present invention, there is provided a difference circuit capable of realizing an accurate extraction of a time difference, simplifying the configuration and reducing the size. be able to.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a differential circuit according to an embodiment of the present invention.

FIG. 2 is a waveform chart shown for explaining the operation of FIG. 1;

FIG. 3 is a circuit diagram showing a PID control circuit to which the present invention is applied.

FIG. 4 is a circuit configuration diagram showing a conventional difference circuit.

FIG. 5 is a waveform chart shown for explaining the operation of FIG. 4;

[Explanation of symbols]

10 detection circuit, 11 proportional circuit, 12 integration circuit, 1
3 Differentiator circuit, 13a Difference circuit, 13b Divider, 1
3c: speed compensation circuit, 14: adder, 20: differentiation circuit,
21 ... Sample hold circuit.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-92107 (JP, A) JP-A-4-43168 (JP, A) JP-A-3-106111 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G05B 11/00-11/60 G06G 7/18

Claims (1)

(57) [Claims] 1. A differential circuit for extracting a difference signal between the present time and one sample before a detection signal periodically sampled by a detection circuit, wherein a signal having a differential waveform is obtained by differentiating the detection signal obtained by the detection circuit. A differentiating circuit to obtain the peak value of the signal obtained by the differentiating circuit for one sampling cycle ,
And a sample-and-hold circuit for generating the differential signal of the above .