JPS61114172A - Voltage detecting device - Google Patents

Abstract

PURPOSE:To detect the peak voltage of an AC signal of a dropout, etc., through simple constitution by triggering a monostable multivibrator whose time constant depends upon the wavelength of an input signal with the comparison output between a reference signal and an input signal. CONSTITUTION:An input signal from a signal amplifier 1 is processed by a couple of voltage comparators 1 and 2 which detect whether the signal is a plus or minus voltage and when the amplitude of the input signal is larger than a reference value, the output of the comparator 1 or 2 triggers the monostable multivibrator whose time constant depends upon the wavelength of the input signal. Then, when the output of the monostable multivibrator 4 continues, the state wherein the peak voltage of the input signal is larger than the specific value is detected and the peak voltage of the AC signal of a dropout, etc., is detected through the simple constitution even when the input signal has a high frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a voltage detection device used for detecting the peak voltage of an alternating current signal, particularly for detecting a dropout of a reproduced signal in a magnetic recording/reproducing device.

2. Description of the Related Art Conventionally, there have been methods for detecting a dropout of a reproduced signal in a magnetic recording/reproducing apparatus, such as using a detection and integration circuit or detecting a peak voltage.

The method using a detection/integration circuit consists of a detection circuit 1o1, an integration circuit 102, and a voltage comparator 103, as shown in FIG. When a signal including a dropout is inputted to point a with the waveform shown in FIG. . The voltage comparator 103 converts this to a certain reference voltage.

By comparing (2), a signal corresponding to dropout can be obtained at the 0 point as shown in FIG. 4C.

The method for detecting the peak voltage is as shown in FIG.
6. Consists of a PLL circuit 106 and an AND circuit 107, which generate a clock synchronized with the peak voltage of the input signal. When a signal including a dropout is inputted to point a with the waveform shown in FIG. A waveform signal is obtained. However, in the case of
Since it is not possible to distinguish whether it is a bump out or a peak interval of the waveform, the PLL circuit 106 generates a clock C synchronized with the input signal as shown in FIG. By taking the AND of the signals of and C, dropout detection d can be obtained at point d as shown in FIG. 6d.

Problems to be Solved by the Invention However, in the method using the above-mentioned detection and integration circuit, dropouts as short as one wavelength are often overlooked because the time constant of the integration circuit 102 is large. In the method of detecting the peak voltage described above, as the frequency of the input signal increases, the P
It is difficult to obtain the LL circuit 106, and accurate dropout detection becomes impossible. In particular, when a signal containing so-called jitter, in which the peak voltage interval varies, such as a magnetic recording/reproduction signal, is input, the PLL circuit 106 becomes out of synchronization, making accurate dropout detection difficult.

SUMMARY OF THE INVENTION Therefore, the present invention provides a voltage detection device that can accurately detect peak voltages of AC signals such as dropouts, and that can be provided at low cost using a relatively simple circuit. This is what I am trying to do.

Means for solving the problems The technical means of the present invention for solving the above problems are as follows:
a signal amplifier that amplifies the amplitude of an input signal; a voltage comparator that operates according to the amplitude of the input signal by the signal amplifier;
The output of this voltage comparator becomes a monostable multivibrator that operates with a time constant that depends on the wavelength of the input signal, and if the amplitude of the input signal is continuously above a certain value, the monostable multivibrator becomes The monostable multivibrator is configured to stop when the monostable multivibrator operates and the amplitude of the input signal is below a certain value.

Function The present invention operates the monostable multivibrator when the amplitude of the input signal is continuously above a certain value as in the above configuration, and operates the monostable multivibrator when the amplitude of the input signal is below the certain value. Because it stops, dropout etc.
The peak voltage of an AC signal can be detected.

EXAMPLE An example of the present invention will be described in detail below with reference to the drawings. In FIG. 1, 1 is a signal amplifier, 2 and 3 are a set of voltage comparators for detecting positive and negative voltages, and 4 is a monostable multivibrator.

When a signal including a dropout is inputted to point 8 with the waveform shown in Figure 2a, the amplitude is amplified by the signal amplifier 1, and then the voltage is amplified by the voltage comparators 2 and 3 as shown in Figure 2. A detection signal S compared to the reference voltage V-) is generated. Furthermore, this signal causes the monostable multivibrator 4 to operate with a time constant of about % of the wavelength of the input signal, so that in the case of a signal without dropout, the monostable multivibrator 4 operates continuously and eliminates dropout. When there is a dropout, the monostable multivibrator 4 stops, and a signal C corresponding to dropout can be obtained as shown in FIG. 2C. In this way, by using the monostable multivibrator 4, which has a time constant of % of the wavelength of the input signal, it is possible to detect dropouts of one wavelength or less, even if the signal contains a lot of jitter. , can be detected without fear of malfunction. It is also possible to operate with high frequency signals.

Although the second embodiment describes the case of detecting dropout of a magnetic recording/reproducing signal, it goes without saying that the present invention can be used to detect the amplitude of other alternating current signals.

Effects of the Invention As is clear from the above description, the present invention includes a signal amplifier that amplifies the amplitude of an input signal, a voltage comparator that operates according to the amplitude of the input signal by the signal amplifier, and a voltage comparator that operates according to the amplitude of the input signal by the signal amplifier. It consists of a monostable multivibrator whose output operates with a time constant that depends on the wavelength of the input signal. Therefore, it is possible to accurately detect peak voltages of AC signals such as dropouts. Furthermore, since it is constructed from a relatively simple circuit, it can be provided at low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the voltage detection device of the present invention, FIG. 2 is a signal waveform diagram thereof, FIG. 3 is a block diagram of a conventional voltage detection device, and FIG. 4 is a signal waveform diagram thereof. FIG. 6 is a block diagram of another conventional voltage detection device, and FIG. 6 is a signal waveform diagram thereof. 4...Monostable multivibrator〇 Name of agent Patent attorney Toshio Nakao and 1 other person Figure 1 Award Figure 2

Claims (1)

[Claims] a signal amplifier that amplifies the amplitude of an input signal; a voltage comparator that operates according to the amplitude of the input signal by the signal amplifier;
The output of this voltage comparator becomes a monostable multivibrator that operates with a time constant that depends on the wavelength of the input signal, and if the amplitude of the input signal is continuously above a certain value, the monostable multivibrator becomes A voltage detection device characterized in that the monostable multivibrator is configured to stop when the monostable multivibrator is activated and the amplitude of the input signal is below a certain value.