JPH04358323A - Device and method for processing optical information - Google Patents

Abstract

PURPOSE:To surely reproduce data by providing a means to cut binarized regenerative data signals when the amplitude of a signal corresponding to the quantity of light reflected from a medium is lowered less than a prescribed value. CONSTITUTION:When a control signal supplied from a system controller to a NOR circuit 129 is at an L level and a reflectance signal is made lower than the threshold level of a comparator 12 for signal cut by dust on an optical card, the output of the comparator 120 is turned from the L level to an H level. Therefore, this output at the H level is inverted at a NOT circuit 128, and the output at the L level is supplied to the NOR circuit 129. A gate signal for signal cut outputted from the circuit 129 is turned to the L level, and no pit detection signal is outputted from an AND circuit 130. Therefore, when the signal corresponding to the quantity of reflected light is recovered, out-of- synchronism is hardly generated, and the data can be reproduced without fail.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention optically records information/
The present invention relates to an optical information processing device and an optical information reproducing method that optically record/reproduce information onto/from a medium to be reproduced.

0002

2. Description of the Related Art FIG. 5 shows an example of the structure of an optical card, with a part thereof shown in enlarged form. The optical card 1 has an information recording section 2, in which pits 3 are formed in each track 5 separated by a tracking guide 4, and information is recorded therein.

[0003] The pit string is recorded by MFM modulation, and the pit intervals represent information "1" and "0".

Next, an optical system for extracting an RF signal representing the brightness and darkness of the pits from the pit row formed on the track 5 of the optical card 1 will be explained with reference to FIG.

FIG. 6 is a block diagram showing an example of a pickup device for recording or reproducing information on the optical card 1. As shown in FIG. In the figure, a laser beam output from a laser diode 21 is made into parallel light by a collimator lens 22, and then enters a prism 23. The laser beam incident surface of the prism 23 is a tapered surface, which allows the cross-sectional shape of the laser beam to be shaped. The laser beam output from the prism 23 is passed through an aperture diaphragm 24 so that only a predetermined range of the laser beam is passed through. This aperture stop 24 allows only a portion of the shaped laser beam having a uniform energy distribution to be used.

The laser beam that has passed through the aperture stop 24 is incident on a polarizing beam splitter 25 having a polarizing surface 25a.

The laser diode 21 emits linearly polarized light, and the direction of its polarization plane is parallel to the polarization direction of the polarization plane 25a of the polarization beam splitter 25 (direction P in the figure). As a result, the laser light passes through the polarization plane 25a.

The laser beam transmitted through the deflection beam splitter 25 is focused and irradiated onto the information recording layer 7 (see FIG. 10) of the information recording section 2 of the optical card 1 by an objective lens 26. The optical axis of this laser beam is made to coincide with the optical axis of the objective lens 26.

On the other hand, the linearly polarized LED light outputted from the LED 31 is made into parallel light by the collimator lens 32, and then enters the polarizing beam splitter 25. L.E.
The polarization direction of the D light is perpendicular to the polarization direction P of the polarization plane 25a of the polarization beam splitter 25. Therefore L.E.
The D light cannot pass through the polarization plane 25a and is reflected there. The LED light reflected by the polarization plane 25a enters the objective lens 26 from a position shifted by a predetermined distance from its optical axis.

The LED light transmitted through the objective lens 26 is focused and irradiated onto the information recording layer 7 (see FIG. 10) of the optical card 1.

The LED light reflected by the information recording layer 7 is incident on the objective lens 26 at a position opposite to the incident position of the incident light from its optical axis. and,
The light transmitted through the objective lens 26 enters the polarizing beam splitter 25 and is reflected by its polarizing plane 25a. As a result, the LED light is transmitted to the surface 33 of the half prism 33.
a, and is focused and irradiated onto a photodetector 35 by a condenser lens 34.

The photodetector 35 has a light-receiving element for focusing, a light-receiving element for data reproduction, and a light-receiving element for tracking. The light receiving element for data reproduction receives a signal corresponding to the pit of the track (RF signal indicating the brightness of the pit).
signals) can be detected.

In FIG. 6, numeral 36 indicates the direction in which the optical card 1 moves.

Next, the process from extracting a pit detection signal from a photocurrent signal, that is, an RF signal, extracted from the light receiving element 35a for data reproduction of the photodetector 35 to reproducing information will be explained with reference to FIGS. 7 to 9. do. 7 is a circuit diagram showing an example of a conventional signal processing circuit, FIG. 8 is a circuit diagram showing an example of a conventional demodulation circuit, and FIG. 9 is a timing chart for explaining the operation of FIGS. 7 and 8. .

FIG. 7 shows a signal processing circuit for extracting a pit detection signal from an RF signal. is the current-voltage conversion amplifier 40
The voltage is converted into a voltage and input to the low-pass filter 50. The low-pass filter 50 removes high-frequency components such as noise in the voltage signal, and then passes it through the high-pass filter 60 to the differentiator 70 and the comparator 90 as shown in FIG. 9(b).
Provides an output with a waveform as shown in . The waveform in FIG. 9(b) corresponds to the optical head detection output reproduction waveform, and is a waveform whose reflectance changes depending on the presence or absence of pits.

The differentiator 70 differentiates the output of the high-pass filter 60 as shown in FIG. 9(b) to obtain an output with a differentiated waveform (equalized waveform) as shown in FIG. 9(c).

Next, the comparator 80 sends out an H level output if the input signal is negative. Therefore, the output of the comparator 80 is as shown in FIG. 9(d). The output of this comparator 80 is input to the B terminal of the retriggerable one-shot multivibrator 100.

Further, the comparator 90 slices the output of the high-pass filter 60 at a certain setting value, as shown in FIG. 9(e).
) is sent to the A bar (means that a bar (horizontal line) is drawn above the letter A. The same applies hereinafter) terminal of the retriggerable one-shot multivibrator 100 via the inverter 103. is input.

In this retriggerable one-shot multivibrator 100, when a falling pulse is supplied to the A bar terminal while the B terminal is in an H level state, or at the falling edge of the A bar terminal, or when the A bar terminal is When a rising pulse is supplied to the B terminal while in the level state, an H level pulse output is sent from the output terminal Q at the rising edge. Therefore, from the output terminal Q of the retriggerable one-shot multivibrator 100,
As shown in (f), a pit detection signal corresponding to the center of each pit is obtained.

Note that the current-voltage conversion amplifier 40 is composed of an operational amplifier 41 and a resistor 42. The low-pass filter 50 is composed of an operational amplifier 51, resistors 52 and 53, and capacitors 54 and 55. The high-pass filter 60 is composed of an operational amplifier 61, resistors 62 and 63, and a capacitor 64. The differentiator 70 includes an operational amplifier 71 and a resistor 7.
2, 73 and a capacitor 74. Comparator 80 is composed of an operational amplifier 81 and resistors 82-84. The comparator 90 includes an operational amplifier 91 and a resistor 92.
96 and a variable voltage source 97. Further, in the retriggerable one-shot multivibrator 100, 101 is a capacitor, and 102 is a resistor. Also,
E0 to E3 are power supply voltages.

Next, the pit detection signal obtained in FIG. 7 is shown in FIG.
The signal is input to the demodulation circuit of the MFM demodulation method.

In FIG. 8, the demodulation circuit is a PLL (Ph
ase Lock Loop) circuit 110 and a data discrimination circuit 111.

The PLL circuit 110 includes a phase comparator 112 to which a pit detection signal as shown in FIG. 9(f) is supplied to one input terminal, and a low-pass filter to which a phase difference signal of the phase comparator 112 is supplied. (LPF) 113 and a voltage controlled oscillator (VCO) 114 to which the output of the low-pass filter 113 is supplied and feeds back the output to the other input terminal of the phase comparator 112.

The PLL circuit 110 receives a pit detection signal as shown in FIG. 9(f) and outputs a synchronizing signal as shown in FIG. 9(g) to one input terminal of the data discrimination circuit 111. A pit detection signal is supplied to the other input terminal of the data discrimination circuit 111. Therefore, the data discrimination circuit 11
1 is determined as "1" if there is a pit detection signal in the H level section of the synchronization signal, and as "0" if there is no pit detection signal (h
) was reproducing the information as shown in the figure below.

[0025]

[Problems to be Solved by the Invention] However, when reading information recorded on the optical card 1, if there is something on the surface of the optical card 1 that obstructs the optical path, such as scratches or dust, for example, as shown in FIG. The pit row of the information recording layer 7 on the substrate 6 (
When there is dust 9 on the transparent protective layer 8 shown in FIG. 10(a), the reflectance signal representing the amount of reflected light from the information recording layer of the information recording section 2 of the optical card 1 is as shown in FIG. 10(b). Along with this, the amplitude of the RF signal modulated by the pit train also decreases as shown in FIG. 10(c). At this time, the pit detection signal may not be able to perform peak detection due to a decrease in amplitude of the signal that should originally be present, as shown by the dotted line in FIG. 10(d), and the pit detection signal may be omitted. In addition, the signal in which the pit detection signal is not removed contains larger jitter than in a normal reproduction state.

If the reflectance drops to almost zero due to scratches or dust on the surface of the transparent protective layer 8 of the optical card 1, the amplitude of the RF signal also drops to almost zero, and in this case pit detection No signal is output. However, normally, when carrying and using the optical card 1, it is difficult for the RF signal to become zero, and more often the signal decreases to a certain degree. There are two reasons for this.

That is, one reason is that in the optical card,
As shown in FIG. 11, since the transparent protective layer 8 formed on the information recording layer 7 is thick, the light spot from the objective lens 26 of the pickup device in FIG. 6 has a diameter of several μm on the surface of the information recording layer 7. However, on the surface of the transparent protective layer 8 where there are scratches or dust (in the case of dust 9 in the figure), the 10
The diameter is several hundred μm, which is 0 times or more. In other words,
If the scratches, dust, etc. are smaller than this several hundred micrometers in diameter, the light will not be completely blocked, and the amplitude of the obtained RF signal will not become zero, but will be reduced to a certain extent.

The second reason is that even if the scratches or dust are larger than the light spot diameter on the surface of the transparent protective layer 8, the transmittance is not zero but a value of several percent to several tens of percent. There are many. Therefore, the amplitude of the obtained RF signal is unlikely to become zero.

For the above reasons, when there is scratches or dust, the pit detection signal may lose the original signal or become a signal containing a large amount of jitter, as shown in FIG. 10(d). . When a signal containing a large amount of jitter is input to the demodulation circuit of FIG. 8, the PLL circuit 110 works to disturb the synchronization of the synchronization signal. Once the synchronization signal is disrupted, even if the scratches and dust are removed and the RF signal and pit detection signal return to normal, the synchronization signal will not return to normal immediately, so the period of the pit detection signal and the synchronization signal will deviate. Data on areas without scratches or dust cannot be played correctly.
A reading error will occur. Such a state is called a synchronization shift, and once the synchronization shifts, a burst error occurs in which all data until resynchronization occurs becomes an error.

An object of the present invention is to detect scratches, dust, etc. on a medium when the amplitude of a signal (reflectance signal, RF signal) corresponding to the amount of reflected light from the medium decreases below a predetermined value.
A light source that can cut binary data signals containing jitter, thereby reducing synchronization when the signal corresponding to the amount of reflected light is restored, and ensuring data reproduction. The purpose of the present invention is to provide an information processing device.

Another object of the present invention is to cut the binary data signal containing jitter related to the specified area, and therefore read another specified area to correspond to the normal amount of reflected light. An object of the present invention is to provide an optical information reproducing method that can reliably reproduce data without losing synchronization when a signal is obtained.

[0032]

[Means for Solving the Problems] The optical information processing device according to claim 1 is an optical information processing device that optically records information on or reproduces information from a medium, in which a signal corresponding to an amount of reflected light from the medium is set to a predetermined value. The present invention is characterized in that it includes a detection and cutoff means that cuts off the output of the binary data signal corresponding to the recorded information on the medium when it is detected that the data signal has fallen below the level recorded on the medium.

[0033] The optical information processing device according to claim 2 is an optical information processing device that optically records or reproduces information on a medium, and in which the output of a binary data signal corresponding to recorded information on the medium is blocked. a control means for controlling whether or not to
Detection and cutoff means for cutting off the output of the binary data signal under the control of the control means when it is detected that the signal corresponding to the amount of reflected light from the medium has fallen below a predetermined value. It is characterized by:

The optical information reproducing method according to claim 3 is an optical information processing apparatus that optically records or reproduces information on a medium, when reproducing recorded information on the medium, reads a specified area on the medium. The present invention is characterized in that if there is a read error even after repeating the reading a predetermined number of times, the specified area is not read.

[0035]

[Operation] In the optical information recording and reproducing apparatus according to claim 1 or 2, when the detection and blocking means detects that the signal corresponding to the amount of reflected light from the medium has decreased to a predetermined value or less, the detection and blocking means automatically or Under the control of the control means, the output of the binary data signal corresponding to the information recorded on the medium is cut off.

[0036] As a result, when scratches, dust, etc. are present on the medium, a signal (RF signal) corresponding to the amount of light reflected from the medium is detected.
When the amplitude of 2 drops below a predetermined value,
The digitized data signal can be cut, and therefore, when the signal corresponding to the amount of reflected light is restored, synchronization is less likely to be lost and data can be reproduced reliably.

Further, in the optical information reproducing method according to claim 3, when reproducing the recorded information on the medium, if a read error occurs even if reading of the specified area on the medium is repeated a predetermined number of times, the specified area is Since reading is not performed, the binarized data signal containing jitter related to the specified area is cut off, so it is necessary to read another specified area and read the signal corresponding to the normal amount of reflected light. When you get it,
Data can be replayed reliably without losing synchronization.

[0038]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

(1). First, one embodiment of the optical information processing apparatus of the present invention will be described using FIGS. 5, 6, 1, 8, and 2.

The optical card applied to the optical information processing apparatus of the present invention is the same as that shown in FIG. 1 described above. Further, the optical card pickup device in the optical information processing apparatus of the present invention is similar to the optical card pickup device shown in FIG. 6 described above. Further, the signal processing circuit in the optical information processing device of the present invention is shown in FIG. Further, the demodulation circuit in the optical information processing apparatus of the present invention is similar to the demodulation circuit shown in FIG. 8 described above.

The output of the signal processing circuit shown in FIG. 1 is input to the demodulation circuit shown in FIG.

The optical information processing device of the present invention and the conventional optical information processing device have different signal processing circuits.

FIG. 1 shows an embodiment of the signal processing circuit of the present invention, in which the conventional signal processing circuit of FIG. , the output of the retriggerable one-shot multivibrator 100 under the control of the system controller. A detection and cutoff circuit 119 is added as a detection and cutoff means of the present invention for cutting off the output of the pit detection signal. Note that the threshold level of the signal cut comparator 120 is set to about 20 to 50% of the normal level of the reflectance signal. This detection and cutoff circuit 119 is composed of a signal cut comparator 120, a knot 128, a NOR circuit 129, and an AND circuit 130.

The signal cut comparator 120 includes an operational amplifier 121 and resistors 122, 123, 125 to 127.
and a variable voltage source 124. A reflectance signal is supplied to the negative input terminal of the operational amplifier 121 via a resistor 122. Here, the reflectance signal may be, for example, a signal extracted from the photodetector 35 in FIG. 6 or an RF signal modulated by the pits of the information recording layer 7 of the optical card 1.
A signal whose modulation frequency has been cut by a low-pass filter is used.

Further, the negative input terminal of the operational amplifier 121 is grounded via a resistor 123 and a variable voltage source 124. Further, the positive input terminal of the operational amplifier 121 is grounded through a resistor 125, and connected to the operational amplifier 121 through a resistor 126.
connected to the output end of the Further, the output end of the operational amplifier 121 is connected to the power supply voltage E4 via a resistor 127.

The output terminal of the operational amplifier 121 is connected to one input terminal of a NOR circuit 129 via a NOT circuit 128. The other input terminal of the NOR circuit 129 is supplied with a control signal from the system controller. The output terminal of the NOR circuit 129 is connected to one input terminal of the AND circuit 130. The other input terminal of the AND circuit 130 is connected to the retriggerable one-shot multibrator 1.
It is connected to the output terminal Q of 00.

In FIG. 1, the same or equivalent parts as in FIG. 7 are denoted by the same reference numerals, and the explanation thereof will be omitted.

Next, the operation of FIG. 1 will be explained using FIG. 2. Note that FIGS. 2(a) to 2(e) are timing charts explaining the operation of FIG. 1.

Now, the case where there are scratches or dust (here, dust 9) on the transparent protective layer 8 formed on the information recording layer 7 of the optical card 1 as shown in FIG. 2(a) and FIG. 11 will be explained. .

If the system controller (not shown)
The control signal supplied to the NOR circuit 129 from
If the reflectance signal falls below the threshold level F of the signal cut comparator 120 as shown in FIG. 2(b) due to dust 9 on the transparent protective layer 8 of the optical card 1, the signal is comparator 12
The output of 0 goes from L level to H level. Therefore, this H level output is inverted by the NOT circuit 128, and the L level output is supplied to the NOR circuit 129. Noah circuit 1
The gate signal for signal cut, which is the output of 29, is shown in Figure 2(d).
As shown in FIG. 2, it becomes L level, and the pit detection signal is not outputted from the AND circuit 130 as shown in FIG. 2(e).

Furthermore, if the control signal supplied from the system controller to NOR circuit 129 is at H level, the output of NOR circuit 129 becomes H level regardless of the other input of NOR circuit 129. Therefore, regardless of the output of the signal cut comparator 120, that is, regardless of the reflectance signal level, the pit detection signal is always outputted via the AND circuit 130.

Note that FIG. 2(c) shows the bypass filter 6
The waveform of the RF signal taken out as a zero output is shown.

(2). Next, other embodiments of the optical information processing apparatus of the present invention will be described using FIGS. 5, 6, 8, 3, and 2.

Here, FIG. 3 is used instead of FIG. 1, and the other points are the same as those described in (1) above, so the explanation will be omitted.

FIG. 3 shows another embodiment of the signal processing circuit in the optical information processing device of the present invention. In the same figure, a high-pass filter 60 is added to the conventional signal processing circuit of FIG.
RF signal (RF signal modulated by pits) which is the output of
The detection and cutoff of the present invention cuts off the output of the pit detection signal, which is the output of the retriggerable one-shot multivibrator 100, under the control of the system controller when it is detected that the pit detection signal has fallen below the threshold level. A detection and cutoff circuit 151 is added as a means.

This detection and cutoff circuit 151 includes a signal cut comparator 140, a retriggerable one-shot multivibrator 148, a NOR circuit 129,
It is composed of an AND circuit 130 and the like.

The signal cut comparator 140 includes an operational amplifier 141 and resistors 142, 143, 145 to 147.
and a variable voltage source 144.

Here, the negative input terminal of the operational amplifier 141 is connected to the output (R
F signal) is supplied. Further, the negative input terminal of the operational amplifier 141 is grounded via a resistor 143 and a variable voltage source 144. Further, the positive input terminal of the operational amplifier 141 is grounded via a resistor 145 and connected to the output terminal of the operational amplifier 141 via a resistor 146. Further, the output terminal of the operational amplifier 141 is connected to the power supply voltage E via a resistor 147.
5. The output terminal of the operational amplifier 141 is the B of the retriggerable one-shot multivibrator 148.
connected to the terminal. Furthermore, the A-bar terminal of the retriggerable one-shot multivibrator 148 is grounded. Further, the retriggerable one-shot multivibrator 148 is connected to the power supply voltage E6 via a resistor 150. Further, the retriggerable one-shot multivibrator 148 is connected to a power supply voltage E6 via a resistor 150 and a capacitor 149 as shown.

The output terminal Q of the retriggerable one-shot multivibrator 148 is connected to one input terminal of the OR circuit 129. The other input terminal of this OR circuit 129 is connected to a system controller (not shown).
A control signal is supplied from the OR circuit 129
The output terminal of is connected to one input terminal of the AND circuit 130. Moreover, the other input terminal of the AND circuit 130 is
Retriggerable one-shot multivibrator 100
is connected to output terminal Q of.

In FIG. 3, the same or equivalent parts as in FIG. 7 and FIG.

Next, the operation of FIG. 3 will be explained using FIG. 2. Now, a case where there are scratches or dust (here, dust 9) on the transparent protective layer 8 formed on the information recording layer 7 of the optical card 1 as shown in FIGS. 2(a) and 11 will be described.

The signal cut comparator 140 outputs an H-level pulse when the amplitude (indicated by the broken line) of the input RF signal from the high-pass filter 60 as shown in FIG. 2(c) exceeds a certain value. Send out. Here, the output pulse width of the retriggerable one-shot multivibrator 148 is set to be greater than or equal to the lowest period of the RF signal, so the comparator 140 continues to trigger the retriggerable one-shot multivibrator 148. Therefore, the output of the retriggerable one-shot multivibrator 148 always maintains the H level. Therefore, the signal cut gate signal output from the OR circuit 129 always maintains the H level as shown in FIG. 2(d). As a result, the AND circuit 130 outputs a pit detection signal as shown in FIG. 2(e).

Next, when the amplitude of the RF signal decreases as shown in FIG. 2(c) and becomes below the threshold level of the comparator 140, the output of the retriggerable one-shot multivibrator 148 becomes L level. At this time, if the control signal is also at L level, the signal cut gate signal output from the OR circuit 129 becomes L level as shown in FIG.
), no pit detection signal is output.

Furthermore, if the control signal supplied from the system controller to NOR circuit 129 is at H level, the output of NOR circuit 129 becomes H level regardless of the other input of NOR circuit 129. Therefore, regardless of the output of the retriggerable one-shot multivibrator 148, that is, regardless of the RF signal level, the pit detection signal is always outputted via the AND circuit 130.

As explained above in (1) and (2),
If there are scratches or dust on the transparent protective layer 8 of the optical card 1 and the amplitude of the RF signal modulated by the reflectance signal or pit decreases, if the control signal from the system controller is at L level. , detection and cutoff circuits 119 and 151 can block (cut) transmission of pit detection signals containing jitter. As a result, when the amplitude of the reflectance signal or the RF signal decreases, the pit detection signal is not input to the PLL circuit 110 of the demodulation circuit in FIG. It operates stably without being disturbed, and can maintain a certain period of the reflectance signal or RF signal before signal decline. Therefore, when the signal levels of the reflectance signal and the RF signal are restored thereafter, synchronization is less likely to be lost, and data can be reliably reproduced.

(3). Next, an embodiment of the optical information reproducing method of the present invention will be described using FIG. 4. In an optical information processing device that optically records or reproduces information on the optical card 1, when reproducing recorded information on the optical card 1, the system controller issues a read command and performs the read process according to the flow shown in FIG. let

That is, first, the optical card 1 is caused to perform a track search (step S1) and read from a designated track (step S2). In this case, it is checked whether the number of read retries is the third time (step S3). If the number of retries is not the third, whether or not the specified track was successfully led (
(Step S4). Then, if the read is successful, the read processing for the designated track is completed, and if the read is not possible (if there is a read error), the system controller sets the control signal to L level and starts reading the designated track again. are repeated (step S5,
S2). Then, when the specified track can be read, the processing flow of FIG. 4 is ended (steps S3 and S4). Also, if the specified track is repeatedly read due to a read error and the number of retries reaches the third time,
Do not read the designated track (step S3)
~Repetition of S5 and S2, step S6).

In this way, when reproducing recorded information on the information recording layer 7 of the optical card 1, even if reading of the designated track 5 (see FIG. 5) of the optical card 1 is repeated three times, the transparent If there is a read error due to scratches or dust on the protective layer 8, the specified track will not be read, so the 2.
The digitized data signal will be cut in advance, and therefore,
When another track is read and a signal corresponding to a normal amount of reflected light is obtained, data can be reliably reproduced without losing synchronization.

[0069] The present invention is not limited to this example, but
Various applications and modifications are possible without departing from the spirit of the invention.

[0070]

As described above, according to the present invention, the following various effects can be obtained.

(1). When there are scratches, dust, etc. on the medium and the amplitude of the signal corresponding to the amount of reflected light from the medium (for example, a reflectance signal or RF signal) falls below a predetermined value, the signal is converted into a binary signal containing jitter. The reproduced data signal can be cut, so that when the signal corresponding to the amount of reflected light is restored, synchronization is less likely to be lost, and data can be reproduced reliably.

(2). Even if the specified area on the medium is read a specified number of times, if there is a read error due to scratches or dust on the medium surface, the specified area will not be read. The binarized playback data signal containing jitter is cut in advance, so when reading another specified area and obtaining a signal corresponding to the normal amount of reflected light, the synchronization will not be lost and the data will not be synchronized. can be played reliably.

(3). When the medium is an optical card, the surface of the medium is exposed, so it is more susceptible to scratches and dust than compact discs (CDs) or optical discs, so the effects of the present invention are great.

(4). Since the reliability of reproducing data recorded on the medium is increased, the operating time of the system is also reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a signal processing circuit in an optical information processing device according to the present invention.

FIG. 2 is a timing chart for explaining the operations of FIGS. 1 and 3;

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

FIG. 4 is a flowchart showing an embodiment of the optical information reproducing method according to the present invention.

FIG. 5 is a plan view showing a configuration example of an optical card.

FIG. 6 is a configuration diagram showing an example of an optical card pickup device.

FIG. 7 is a circuit diagram showing an example of a signal processing circuit in a conventional optical information processing device.

FIG. 8 is a circuit diagram showing an example of a demodulation circuit in an optical information processing device.

FIG. 9 is a timing chart for explaining the operations in FIGS. 7 and 8;

FIG. 10 is an explanatory diagram for explaining conventional problems.

FIG. 11 is an explanatory diagram for explaining conventional problems.

[Explanation of symbols]

80, 90 Comparator 100 Retriggerable one-shot multivibrator 119, 151 Detection and cutoff circuit 120 Signal cut comparator 128 Knot circuit 129 NOR circuit 130 AND circuit

Claims (3)

[Claims] Claim 1: In an optical information processing device that optically records or reproduces information on a medium, when it is detected that a signal corresponding to the amount of reflected light from the medium has decreased to a predetermined value or less, the information recorded on the medium is An optical information processing device characterized by comprising detection and blocking means for blocking output of a corresponding binary data signal. 2. In an optical information processing device that optically records or reproduces information on a medium, control for controlling whether to cut off output of a binary data signal corresponding to information recorded on the medium. means for detecting that, when it is detected that a signal corresponding to the amount of reflected light from the medium has decreased to a predetermined value or less, the output of the binary data signal is cut off under the control of the control means; and a blocking means. 3. In an optical information processing device that optically records or reproduces information on a medium, when reproducing information recorded on the medium, reading of a specified area on the medium is repeated a predetermined number of times. An optical information reproducing method characterized in that if there is an error, reading of the designated area is not performed.