JPS6116070A - Detector for optical information - Google Patents

Abstract

PURPOSE:To detect optical information with an extremely small number of reproduction errors and high reliability by reproducing the digital information recorded to a recording medium with just a single bit defined as a unit recording part and detecting each positive or negative peak point contained in a reproduction signal. CONSTITUTION:A recording bit series A where just one-bit is used as a unit recording part is formed to a recording medium which can be reproduced optically as a unit recording part series B. The series B is reproduced and a reproduction signal C having a peak point (c) corresponding to each unit recording part (a) is sent to a differentiator 1 via a DC cut-off amplifier. A differential signal D is detected by a zero cross point detector 2 in the form of a zero cross point detecting pulse series E and sent to an AND gate 3. While the signal C is also supplied to a limiter 4, and the output signal F of the limiter 4 is sent to the other input of the gate 3. A peak point pulse series G is delivered to the output side of the gate 3. The series B is detected from the series G. Thus the optical information can be detected with an extremely small number of reproduction errors and high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field to which the invention pertains) The present invention relates to digital information recorded on an optically reproducible recording medium, particularly digital information in which only the pit 1'' is recorded as a unit recording part, to the reproduction signal thereof. The present invention relates to an optical information detection device that can detect optical information more accurately.

(Prior Art) This type of conventional detection device detects the timing at which a reproduction signal becomes equal to a predetermined reference voltage at the rising edge or falling edge, and reproduces digital information from this. There was one that used a DC regenerative amplifier and a voltage comparator, but the reproducing voltage and reference voltage drift due to temperature fluctuations, and the reproducing voltage fluctuates due to deviations and non-uniformities in the characteristics of the recording medium, resulting in timing errors, i.e. The disadvantage was that there were large playback errors. There was also a device that used a DC cutoff amplifier and a zero-crossing point detector, but the zero potential fluctuated depending on the non-uniform characteristics of the recording medium and the length of the distance between adjacent ports ``1'' (C1 Same as above). There was a drawback.

(Objective of the Invention) It is an object of the present invention to solve these drawbacks and realize a highly reliable optical information detection device with few reproduction errors.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention provides an optical system that detects digital information recorded in an optically reproducible recording medium as a recording part in which only bit "1" is in the r1 position from the reproduced signal. The target information detection device a3 includes a differentiator that differentiates the reproduced signal, a Yuki-onna point detector that generates a pulse signal every time the output signal of the differentiator crosses zero potential, and a It has a limiter that outputs a correspondingly high or low signal, and a goo 1 that allows the output pulse of the Yuki-onna point detector to pass only when the output of the limiter is either high or low, This method is characterized by detecting either the positive or negative peak points in the reproduced signal.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which 1 is a differentiator, 2 is a Yuki-onna point detector, 3 is an AND gate, and 4 is a limiter. All of the above circuits are well known, and the Yuki-onna point detector 2 outputs a narrow pulse signal every time its human power signal 8 crosses the zero potential, and the limiter 4 outputs a high signal when its input signal is positive. It outputs a level signal, and when it is negative, it outputs a low level signal.

Next, the operation will be explained with reference to FIG. 2 showing signals of each part. Recording Pit] One series △ indicates the original data of information recorded on a recording medium (not shown), and at least a bit O'' is inserted between bit ``1'' and the following pit 1''. This includes one item. On the actual recording medium, only the dot r (I I+) of the recording bit series A is recorded as a unit recording part.The unit recording part series B is the unit recording part recorded and formed on the recording medium. The situation is shown in the figure, where a is a unit recording section corresponding to "1" at pitch 1, and b is an unrecorded section that separates each of the unit recording sections a from each other.

The unit recording section series B on the recording medium is read by an optical reproducing head (
(not shown), a reproduced signal C having a peak point C corresponding to each intermediate recording portion a is obtained. The reproduced signal C
is a DC cut-off amplifier (
The signal is amplified and its DC component is cut off at the point U) shown in the figure, and further subjected to waveform equalization as required, and then sent to the differentiator 1. In addition, curve d is regeneration (fi Month C 1ii
The zero potential when the i-flow component is blocked is not shown. The re/:1-signal C is differentiated by a differentiator 1 and sent to four differentiated signals and further to a Yuki-onna point detector 2. The Yuki-onna point detector 2 generates a pulse signal every time the differential signal crosses zero potential, and generates a Yuki-onna point detection pulse series consisting of a large number of pulse signals.
It is sent to one of the close terminals of ND gate 3. However, at this time, the pulse signals in the pulse sequence E include not only those corresponding to each peak point C, but also those corresponding to the peak I'd on the opposite side between each peak point C.

On the other hand, the reproduction signal C is also sent to the limiter 4, and is at a high level during the period when the potential is positive, that is, the period when the potential is greater than the zero potential d, and during the period when the potential is negative, that is, the period when the potential is smaller than the zero potential d. A low level output signal F is obtained. This output signal F
is sent to the other input terminal of the dΔNO gate 3. On the output side of the AND gate 3, a peak point pulse sequence G, which is an AND signal of the Yukionna point detection pulse sequence F and the limiter output signal F, is output. That is, a pulse signal corresponding only to the peak point C of the reproduced signal C is obtained.

Since the interval between adjacent pulses of the pulse signal corresponding only to the peak point C of the reproduced signal C is approximately equal to the interval between the corresponding unit recording parts (J), from the peak point pulse series G to the intermediate recording part The partial sequence B can be detected.Furthermore, in combination with well-known clock reproduction in digital magnetic recording, etc., it is possible to reproduce the sequence A from the peak point pulse sequence G to the recording pitch.

If the output polarity of the optical reproducing head (or an amplifier connected immediately after it) is reversed, and the waveform of the signal C is inverted, the output signal of the limiter 4 is inverted and the output signal of the AND gate 3 is inverted. All you have to do is enter it. Further, the DC component of the reproduced signal C may be cut off immediately before the limiter 4.

(Effects of the Invention) As explained above, according to the present defense, optical information detection detects digital information in which only bits 1111+ are recorded as a unit recording part on an optically reproducible recording medium from the reproduced signal. The apparatus includes a differentiator that differentiates the reproduced signal, a Yuki-onna point detector that generates a pulse signal every time the output signal of the differentiator crosses a zero potential, and 11 of the reproduced signal.
- A limiter that outputs a high/low signal in response to a negative signal, and a limiter whose output passes through the output pulse of the 1) C zero-crossing point detector only during either the high or low period. Since it has a gate 1- and detects each positive or negative peak point in the reproduced signal, fluctuations in the reproduction voltage or zero potential, which were problems with the conventional detection device d, can be avoided. This has the advantage that fluctuations have no effect, there are extremely few reproduction errors, and a highly reliable optical information detection device can be provided.

[Brief explanation of the drawing]

The drawings show an example of the present invention. Fig. 1 is a block diagram of the detection device of the present invention, and Fig. 2 shows the signals of each part.
FIG. 1...Differentiator, 2...Yukionna inspection t11
device, 3...AND gate, 4...limiter.

Claims (1)

[Claims] An optical information detection device for detecting digital information in which only bit "1" is recorded as a unit recording part on an optically reproducible recording medium from a reproduced signal, comprising: a differentiator for differentiating the reproduced signal; and a differentiator for differentiating the reproduced signal; a zero-crossing point detector that generates a pulse signal every time the output signal of the device crosses a zero potential; a limiter that outputs a high/low signal corresponding to the positive or negative of the reproduced signal; and an output of the limiter. and a gate that allows the output pulse of the zero-crossing point detector to pass only during either high or low periods, and detects each positive or negative peak point in the reproduced signal. An optical information detection device characterized by: