JPH01133266A - Information reproducing device - Google Patents

Abstract

PURPOSE:To improve information reproducing accuracy by adjusting a threshold voltage to be the reference of the binarization of the output signal of an optical sensor and executing the duty correcting of a binarization signal. CONSTITUTION:A detected light flux reflected or transmitted at an information recording carrier, in which an information pattern is recorded, is detected with a sensor array 107, this detecting signal is binarized with a binarization circuit 102, and information is reproduced. A binarization signal 39 is sent from the circuit 102 to a binarization duty correcting circuit 120. In the circuit 120, the difference between the duty ratio of the signal 39 and the duty ratio set with a pattern having a prescribed duty ratio is obtained, and an obtained difference signal 62 is sent to an analog switch 60. The switch 60 inputs a threshold voltage signal 63 set to a prescribed value to the inversion input terminal of a comparator 52 by a switching with the value of the signal 62. The duty correcting of the binarizing signal can be executed by the adjustment of this threshold voltage, and the information reproducing accuracy can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an information reproducing device, and in particular, detects a detection light beam reflected or transmitted by an information record in which information is recorded, with an optical sensor, The present invention relates to an information reproducing device that obtains a binary signal from the output signal of this optical sensor.

[Prior art]

Conventionally, information recording carriers used for recording information using a light beam and reproducing the recorded information using a light beam have been known in various forms such as a card shape, a disk shape, and a tape shape. It is being Among these, optical information recording carriers formed in the form of cards (hereinafter referred to as "optical cards") are expected to be in great demand as information recording carriers that are easy to manufacture, have good portability, and have good accessibility. ing.

FIG. 3 is a schematic plan view showing an example of the configuration of an optical card.

FIG. 4 is a partially enlarged view of the recording format of the optical card.

In FIG. 3, an information recording area 2 is provided on the optical card 1, and the information recording area 2 is formed by a plurality of bands 3 arranged in rows. A large number of information tracks 4 are arranged in these bands 3, and each track 4 has several tens to ten information tracks.
It has an information amount of about 0 bits.

The pits are recorded as a combination of high reflectance areas and low reflectance areas.As shown in FIG. It is composed of an identification area 22 which is separated from and used for recognition, an information area 23 where information modulated by MFM modulation or the like is recorded, and an end pit area 24 indicating the end of information. The information area 23 consists of a start pit 30 indicating the beginning of information and an information section in which information is recorded. , Note that arrow A indicates optical card 1 during playback.
arrow C indicates the information reading direction of the optical head during reproduction.

FIG. 5 shows a schematic diagram of a device used for recording and reproducing the optical card as described above.

In the figure, an optical card 1 is placed on a belt 5 and can be moved back and forth in the direction of arrow A by a rotation mechanism 6. Information recorded on the optical card 1 is read and reproduced track by track by an optical head 11. Light from a light source 7 such as an LED is focused by a lens system 8 and illuminates the original card 1. The image of the track of the optical card 1 is formed on a one-dimensional sensor array 10 by an imaging optical system 9. Thus, an electrical signal corresponding to the information recorded on the track 4 is output from the sensor array 10.

The operation of reading the information track υ by the sensor array 10 will be described below.

FIG. 6 is a partially enlarged schematic diagram of the identification area of the optical card 1 shown in FIG. 4. However, the shaded area in the figure indicates a low reflectance area and represents information "1".

Further, a blank area indicates a high reflectance area and represents information "0".

In the figure, 12-a, 12-b, and 12-c are three continuous information tracks in the direction of arrow A of the optical card 1, and 13 is an identification area.

Assuming that the minimum bit width in the optical card 1 is I, the identification area has diagonal line parts 17 and 20 on both sides, blank parts 18 and 19 at I from both sides toward the center, and in the center. It is formed with a 4T diagonal line portion 14. However, the center diagonal line part 14 has a width in the track arrangement direction (direction A) that is approximately 1/2 the width of the information track (for example, 12-a), and is located approximately in the center of the information track in the width direction. ing.

FIGS. 7(a) and (b) show identification area 1 in FIG.
3 is a binary signal obtained as a result of modulating the above-mentioned /CC minimum bit IT in correspondence with the minimum inversion interval of the signal. However, FIG. 7 (11) is a binary signal when the reading position of the sensor array 10 is in the on-track state, that is, when it corresponds to the position shown by the thick line 15,
FIG. 7(b) shows a binary signal when the reading position of the sensor array 10 straddles adjacent information tracks, for example, straddles information tracks 12-b and 12-C. As shown in the figure, a sensor array 10
When the reading position is at the position indicated by the thick line 15 in FIG. 6, the detected signal has a maximum inversion interval of 4T (FIG. 7(a)). Further, when the reading position of the sensor array 10 is at the position indicated by the thick line 16, the detected signal has a maximum inversion interval of 6T (FIG. 7(b)).

However, when a signal having such inversion intervals of 4T and 6T is recorded in the information area using the MFM modulation method, for example, the information area has IT and 1.5T.

Since only a 2T width signal is obtained, it can be clearly distinguished from the signal in the information area.

Thus, by scanning the sensor array 10, as shown in FIG.
) is detected, it can be determined that the reading position of the sensor array 10 is in the on-track state,
If the signal no-turn of FIG. 7(,) is detected again after the signal pattern of FIG. 7(b) is detected, the sensor array 1
It can be identified that the 0 reading υ position has moved to a new track.

Further, the information track reading operation 9 by the sensor array 10 is started by detecting the signal shown in FIG. 7(,).

FIG. 8 is a block diagram of a circuit for detecting the recording signal of the information track as described above.

As shown in the figure, the sensor array 10 is driven by a control signal 108 from the sensor array Drino-kai-101. From the sensor array 10, an analog waveform signal 107 corresponding to the image of the track on the optical card projected by the optical system enters the sensor array driver 101, and further enters the binarization circuit 102 as a signal 109. The signal 110 digitized by the circuit enters an identification area detection circuit 103, an information demodulation circuit 104, and an end pit detection circuit 105. The identification area detection circuit 103 detects the signals shown in FIGS. 7(,) and (b) described above, and outputs a signal indicating the on-track state, a signal indicating moving to a new track, and a signal indicating the starting position of the information area. 111 to the information acquisition circuit. The information demodulation circuit 104 receives an on-track signal 114 from the identification area detection circuit 103.
In response to this, the beginning of the information is determined, and a signal modulated by, for example, combat modulation is demodulated and sent to the information acquisition circuit 106 as an information signal 112. The end pit circuit 105 detects an end pit and sends a signal indicating the end of the information and a signal 113 indicating the transition to a new track to the information acquisition circuit 106. In the information acquisition circuit 106, the above 11
Based on the signals of 1, 112, and 113, the sensor array 10 scans one track a plurality of times and captures the correct signal once from among the signals obtained.

Furthermore, a method for detecting the starting position t' of the information area in the above-mentioned recording format will be explained based on FIG.

In FIG. 9, (a) shows a binary digitized signal at the time of on-track. In addition, signal 21 a, 2 in the figure
2a, 23a, 24a, 30m, and 31m correspond to each area in the information track 4 in FIG. The corresponding signals are obtained from each region.

Further, the signal shown in (b) is a signal indicating on-track detected by the identification area detection circuit 103.

(c) is a dirt signal indicating dirt created by the on-track signal shown in (b). The signal shown in (d) is an information signal demodulated by the information demodulation circuit 104.

According to the signal obtained as described above, when a level of 1'' is detected for the first time in the dirt shown in (,), it is determined as a start pit, and the next pit is the beginning of information. The sensor array 10 reads the information on the optical card, and the sensor array 10 reads the information on the optical card.
The operation of outputting a binary signal will be explained in detail.

FIG. 10 is a block diagram for explaining the binarization circuit. In the figure, a video signal 10 from a sensor array 10 is shown.
9 is sent, is differentiated by a differentiating circuit 45 serving as differentiating means, and a differential signal 49 is detected by a maximum value detector 46 serving as a detecting means;
It is output to the minimum value detector 47. The local maximum value detector 46 detects the extremely thick value of the differential signal 49 and outputs a local maximum detection signal 50, and the local minimum value detector 47 detects the local minimum value of the differential signal 49 and outputs a local maximum detection signal 51. Output. A flip-flop 48 serving as a signal generating means changes the signal level of the binary signal 39 from a low level to a high level using a maximum value detection pulse 50, and changes the signal level of a binary signal 39 from a high level to a low level using a minimum value detection pulse 51. and changes.

FIG. 11 is a waveform diagram of output signals of each constituent means of the binarization circuit (a) to (6).

11(,) is a waveform diagram of the video signal 21 output from the sensor array 10. The video signal 109 is a DC voltage component and an AC voltage which is a modulation signal corresponding to the strength of the amount of light incident on the sensor array 10. The result is a waveform in which the components are superimposed. In the figure, the amount of light incident on the sensor array 10 is greater in the lower voltage portion of the video signal 109. Therefore, the peak on the negative side of the AC voltage component indicates a high reflectance portion of the optical card, and the peak on the positive side indicates a low reflectance portion. That is, the unevenness of the AC voltage component indicates the content of recorded information. Note that the DC voltage component of the video signal 109 fluctuates due to the information turn in the information track, sensitivity unevenness between each element of the sensor array 10, illumination unevenness of the illumination optical system 9, and the like.

When this video signal 109 is applied to the differentiating circuit 45, the differentiated signal becomes the video signal 109 as shown in FIG. 11(b).
The point with the maximum slope of the falling part of is the minimum value,
The point with the maximum slope of the rising portion shows the local maximum value, and the fluctuations in the DC voltage component are completely removed.

The extreme value of the differential signal 49 accurately indicates the boundary between the high reflectance Noreen and the low reflectance Noreen recorded on the optical card, and no phase error occurs due to fluctuations in the DC voltage component.

The differential signal 49 is applied to a local maximum value detector 46 and a local maximum value detector 47, and from the local maximum value detector 46, it is sent from the local maximum value detector 46 as shown in FIG.
), a maximum value detection pulse 50 is output, and the minimum value detector 47 outputs a minimum value detection pulse 51, as shown in FIG. 11(d).

As shown in FIG. 11(,), the flip-flop 48 is
The output signal level is changed by the maximum value detection pulse 50 and the minimum value detection pulse 51, and a binary signal 39 is output.

FIG. 12 is a circuit diagram showing an example of the configuration of the differentiating circuit 45.

FIG. 12(,) shows a differentiating circuit using a capacitor and a resistor, and FIG. 12(b) shows a differentiating circuit using an operational amplifier. In either circuit configuration, by inputting the video signal 21), a differential signal 49 is output.

FIG. 13 is a circuit diagram showing a configuration example of the maximum value detector 46, the minimum value detector 47, and the flip-flop f4B.

The extreme value detector 46 is composed of a comparator 52 and a reference voltage source 54 connected to the inverting input terminal of this comparator, and the signal voltage corresponding to the maximum value of the differential signal 49 is compared with the reference voltage v1, and the maximum value is detected. A detection signal 4 and a signal 50 are output.

The minimum value detector 47 is composed of a converter 53 and a reference voltage source 55 connected to the inverting input terminal of the converter, and the signal voltage corresponding to the minimum value of the differential signal 49 is compared with the reference voltage v2. , Minimum value detection node 51
is output.

Each reference voltage value v1 of the reference voltage source 54.55
+v2 is set in consideration of the fluctuation range of the maximum value and minimum value of the differential signal 49.

Flip flop 48 is D slip flop 5
6, the maximum value detection node 50 is connected to the preset terminal of the D slip-flop 56, and the minimum value detection node 51 is connected to the clear terminal of the D flip-flop 56. The D flip-flop 56 is activated by each pulse input to the preset terminal and the clear terminal.
The output of the Q terminal becomes a binary signal 39 as shown in FIG. 11 (@).

In this way, the pits/turns in the high reflectance area and the low reflectance area on the optical card can be faithfully set to high level and low level of the binary signal.

[Problem that the invention seeks to solve]

However, in an actual system, even if the bit width is the same when creating an optical card, an error of about ±1 μm occurs between IT in a high reflectance area and I in a low reflectance area, for example. Also, this error is not constant for all cards, and varies between lofts. Now, if the IT width is 10 .mu.m bits, there will be as much as 10 inches of jitter, which will significantly reduce the margin of the information demodulation circuit and reduce the accuracy of information reproduction.

[Means for solving problems]

The information reproducing device of the present invention is an information reproducing device that detects a detection light flux reflected or transmitted by an information recording carrier on which an information pattern is recorded with an optical sensor, and obtains a binary signal from the output signal of the optical sensor. The present invention is characterized by comprising means for adjusting a threshold voltage serving as a reference for binarizing the output signal of the optical sensor and correcting the duty of the binarized signal.

[For production]

The information reproducing apparatus of the present invention detects the difference between the duty ratio of the set information A' turn and the duty ratio of the binary signal obtained from the information pattern actually recorded on the information recording carrier by outputting the optical sensor. It adjusts the threshold voltage, which is a reference for signal binarization, and corrects the duty ratio of the binarized signal to the originally set duty ratio of the information nodes.

[Example] Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the information reproducing apparatus of the present invention.

FIG. 2 is a circuit configuration diagram showing a part of a 7''-T correction circuit and a part of a binarization circuit for a binarized signal.

Note that the information reproducing apparatus of the present invention shown in FIG. 1 and the second
In the circuit configuration diagram shown in the figure, FIG.

Components that are the same as those shown in FIG. 13 are given the same reference numerals.

As shown in FIG. 1, the information reproducing apparatus of the present invention is obtained by adding a binarization duty correction circuit to the information reproducing apparatus shown in FIG. 8.

First, a method for detecting a discrepancy between the duty ratio of a set information pattern and the duty ratio of a binary signal obtained from the information pattern actually recorded on the information recording carrier will be described.

Predetermined data recorded on the information record carrier in advance
A pattern area having a tee ratio is provided. This pattern area may be specially provided, or the conventionally provided preamble area 21, identification area 22, etc. may be used.

As shown in FIG. 1, the sensor array 10 is driven by a control signal 108 from the sensor array driver 101. Then, from the sensor array 10, an analog waveform signal 107 corresponding to the image of the pattern of the above-described predetermined duty ratio on the optical card projected by the optical system enters the sensor array driver 101, and is further converted into a binary signal 109. Enter circuit 102.

As already explained using FIG. 10, the signal 109 is differentiated by the differentiating circuit 45, which is differentiating means, and the differentiated signal 49 is output to the maximum value detector 46 and the minimum value detector 47, which are detecting means. The maximum value detector 46 detects the maximum value of the differential signal 49, outputs a maximum value detection pulse 50, and detects the maximum value of the differential signal 49.
7 detects the minimum value of the differential signal 49 and outputs a minimum value detection pulse 51. Free lag frog 4 as signal generation means
8 changes the signal level of the binarized signal 39 from low level to high level by the local maximum detection pulse 50, and changes the signal level of the digital signal 39 from high level to low level by the local minimum detection pulse 51. let

This binarized signal 39 is obtained by reproducing the mother turn having the predetermined duty ratio, and the binarized signal 39 is converted into a binarized duty correction circuit 1.
Send to 20. In this duty correction circuit 120, the difference between the duty ratio of this binary signal 39 and the duty ratio set for the pattern having the predetermined duty ratio is determined, and as shown in FIG. signal 6
2 to the analog switch 60.

This analog switch 60 has a resistor array 61 connected to +V on one side and ground on the other, and switches the switch according to the value of the difference signal 62. A threshold voltage signal 63 set to a predetermined value is input to the terminal. The correspondence between this threshold voltage and the difference signal must be determined in advance, or
Alternatively, it is set by determining the threshold voltage at which the difference signal becomes O by repeating the reading of I lean having a predetermined duty ratio and the detection of the difference signal several times.

By adjusting this threshold voltage, the slice level of binarization in the condenser is varied, and data correction can be performed. In this embodiment, the threshold voltage of the comparator 52 of the extremely large value detector 46 is changed, but the threshold voltage and voltage of the comparator 53 of the extremely minimum value detector 47 may be changed, or both may be changed at the same time. You may go.

〔Effect of the invention〕

As explained above, according to the information reproducing device of the present invention,
By adjusting the threshold voltage, which is the standard for binarizing the output signal of the optical sensor, and correcting the duty of the binarized signal, bit jitter is reduced and the margin of the information demodulation circuit ( can be increased, and information reproduction accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of an information reproducing apparatus of the present invention. FIG. 2 is a circuit diagram showing a part of the data correction circuit for the binary signal and a part of the binarization circuit. FIG. 3 is a schematic plan view showing an example of the configuration of an optical card. FIG. 4 is a partially enlarged view of the recording format of the optical card. FIG. 5 shows a schematic configuration diagram of a device used for recording and reproducing an optical card. FIG. 6 is a partially enlarged schematic diagram of the identification area of the optical card. FIG. 7 is a waveform diagram showing a nine-binarized signal corresponding to the identification area shown in FIG. FIG. 8 is a block diagram of a circuit for detecting the recording signal of the information track as described above. FIG. 9 is a waveform diagram for explaining a conventional method of detecting the starting position of an information area. FIG. 10 is a block diagram for explaining the binarization circuit. FIG. 11 is a waveform diagram of the output signals of each constituent means of the binarization circuit (,) to (,). FIG. 12 is a circuit diagram showing an example of the configuration of a differential circuit. FIG. 13 is a circuit diagram showing a configuration example of a maximum value detector, a minimum value detector, and a flip-flop. 10: Sensor array, 60: Analog switch, 61:
Resistor array, 62: difference signal, 63: threshold voltage signal,
101: Sensor array driver, 102: Binarization circuit, 103: Identification area detection circuit, 104: Information demodulation circuit,
105: End pit detection circuit, 106: Information intake circuit, 120: Binarization duty correction circuit. Agent Patent Attorney Minoru Yamashita Hirahoki 2 Cause Figure 3-Q -0 Figure 9 Figure 12 (a) (b) Figure 13 4.6

Claims (1)

[Claims] (1) An information reproducing device in which a detection light beam reflected or transmitted by an information recording carrier on which an information pattern is recorded is detected by an optical sensor, and a binary signal is obtained from the output signal of the optical sensor, the output of the optical sensor being An information reproducing apparatus characterized by comprising means for adjusting a threshold voltage serving as a reference for binarizing the signal and correcting the duty of the binarized signal.