JPH03219466A - Waveform shaping device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a waveform shaping device that reproduces and digitizes information recorded on a recording medium.

2. Description of the Related Art In recent years, many information recording and reproducing devices using optical means have been developed, and a large demand is expected to continue in the future.

A conventional waveform shaping device will be explained below.

FIG. 4 is a block diagram showing the configuration of a conventional waveform shaping device, in which 1 is an optical/electrical signal converter, 2 is an extreme value detection and holding circuit, 3 is an offset circuit, 4 is a comparator, and 5.6 is a single unit. It is a stable multivibrator.

The operation of the conventional waveform shaping device configured as described above will be described below.

First, when an optical signal as shown in FIG. 5 enters the input terminal 11 of the optical/electrical signal converter 1, it enters an extreme value detection and holding circuit (hereinafter referred to as a peak hold circuit) 2 and an offset circuit 3. This peak hold circuit 2 detects the minimum value and then holds this value, so the waveform outputted to the output terminal 22 is the sixth waveform.
It will look like the picture. On the other hand, the offset circuit 3 shifts the level of the input signal to a lower level and outputs it to the output terminal 32 as shown in FIG.

In comparator 4, peak hold circuit 2 and offset circuit 3
As shown in FIG. 7, when the input signals 41 and 42 supplied from the
42, OV is output to the output terminal 43.

In addition, the monostable multivibrator (hereinafter abbreviated as the first MMV) 5 becomes 1 when the trigger that changes from +5■→0■ is applied.
A pulse is generated at output terminal 52.

Therefore, as shown in Figure 7, 1 for the peak of the reproduced signal.
pieces of digital data are output.

The signal of the output terminal 52 of the first MMV 5 is transmitted to the input terminal 61 of the monostable multivibrator (hereinafter abbreviated as the second MMV).
to go into. The second MMV 6 generates one pulse at the output terminal 62 when a trigger that changes from +5■→0■ is applied. As shown in FIG. 8, the pulse generated at the output terminal 62 (hereinafter referred to as a reset pulse) is transmitted to the peak hold circuit 2.
During the generation of the set pulse, the output voltage of the peak hold circuit 2 becomes +4.sup., and after the input of the reset pulse, the peak hold circuit 2 returns to the state where it performs the extreme value detection and holding operation again.

As described above, the conventional waveform shaping device operates to sequentially detect the minimum value of the reproduced input signal and simultaneously output digital data indicating the detection of the minimum value.

Problems to be Solved by the Invention However, in the conventional configuration described above, when the reproduction input signal remains constant for a long time, such as when reproducing an unrecorded part of a recording medium, as shown in FIG. The output signal gradually decreases and intersects with the output signal of the offset circuit 3, producing unnecessary digital data, and when checking whether the part has been recorded or not, it is determined that the part has been recorded even though it is an unrecorded part. The problem was that

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a waveform shaping device that can prevent the occurrence of digital data even if the reproduced signal is constant. shall be.

Means for Solving the Problems To achieve this object, the waveform shaping device of the present invention includes a digital signal generator that converts an analog signal into a digital signal, and a continuous pulse detector that detects the continuity of the digital signal. It is characterized by:

Effect: This configuration can prevent unnecessary digital data from being generated when the input signal for waveform shaping remains constant for a long time.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a waveform shaping device in an embodiment of the present invention. In FIG. 1, 7 is a continuous pulse detector, and 8 is a digital signal generator. Note that the optical/electrical signal converter 1, extreme value detection and holding circuit 2, offset circuit 3, comparator 4, and mono multi-high break 5.6 are the same as those in the conventional example.

The operation of the waveform shaping device of this embodiment configured as described above will be explained below.

First, when an optical signal as shown in FIG. 2 enters the input terminal 11 of the optical/electrical signal converter 1, the output voltage of the peak hold circuit 2 gradually decreases, and the third A waveform like the one shown in the figure appears.

As a result, the output terminal 43 of the comparator 4, the output terminal 52 of the first MMV5, and the output terminal 62 of the second MMV6 are
A waveform like the one shown in the figure appears.

The signal at the output terminal 62 of the second MMV 6 enters the continuous pulse detector 7, which is a triggerable monostable multivibrator, +5V→0■
Generates one pulse when the trigger is applied. Furthermore, if a trigger is applied for a time shorter than the output pulse width, the output pulse width will be extended by that amount. Further, the digital signal generator 8 is a monostable multivibrator,
1 when +5■→0■ trigger is applied to input terminal 81
Generates a pulse. 82 is a digital signal generator 8
When the signal level is +5V, the digital signal generator 8 is in an operating state, and when the signal level is 0V, it is in an inactive state, and the output terminal 83 outputs 0. Therefore, when an optical signal as shown in Fig. 2 is received, the continuous pulse detector 7 and the digital signal generator 8
The input and output of is as shown in Figure 3.

Therefore, when the reproduction signal is constant for a long time, such as when reproducing an unrecorded part of a recording medium, digital data is not output, but when reproducing a recorded part, digital data is output.

As described above, according to this embodiment, by providing the continuous pulse detector and the digital signal generator, it is possible to prevent unnecessary digital data from being generated when the reproduced signal remains constant for a long time.

In this embodiment, the input of the continuous pulse detector is connected to the second MM.
Although the input is taken as the output of V6, this input may also be the output of the first MMV5.

Effects of the Invention As described above, the present invention provides a continuous pulse detector and a digital signal generator to prevent this from occurring even if the reproduced signal remains constant for a long time and digital data is generated. Furthermore, by using a retriggerable monostable multivibrator as the continuous pulse detector and a monostable multivibrator as the digital signal generator, it is possible to output digital data corresponding to the recorded information during playback of the recording section. This makes it possible to realize a waveform shaping device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a waveform shaping device according to an embodiment of the present invention, and FIGS. 2 and 3 are main parts of the waveform shaping device according to an embodiment of the present invention. FIGS. 8 and 9 are main part waveform diagrams during operation of a conventional waveform shaping device. DESCRIPTION OF SYMBOLS 1... Optical/electrical signal converter, 2... Extreme value detection holding circuit, 3... Offset circuit, 4...
... Comparator, 5 ... Monostable multivibrator, 6 ... Monostable multivibrator, 7
...Continuous pulse detector, 8...Digital signal generator.

Claims (3)

[Claims] (1) A digital signal generator that receives an analog signal obtained by reproducing information recorded on a recording medium and converts it into a digital signal, and a continuous pulse detector that detects continuity of the digital signal, the continuous pulse detector The operation or non-operation of the digital signal generator is determined according to the output of the recording medium, and the continuous pulse detector operates the digital signal generator when reproducing signals from the recorded portion of the recording medium, and continuously operates the digital signal generator when reproducing unrecorded portions of the recording medium. A waveform shaping device characterized in that a pulse detector is configured to disable a digital signal generator. (2) The waveform shaping device according to claim 1, wherein the digital signal generator is a monostable multivibrator. (3) The waveform shaping device according to claim 1, wherein the continuous pulse detector is a triggerable monostable multivibrator.