JPH05217170A - Optical information recording and playback apparatus - Google Patents

Abstract

PURPOSE:To provide a low-cost optical information recording and playback apparatus wherein the relative movement speed between an optical recording medium and an optical head can be constituted without a need for a special prerecorded pattern in each track and without being affected by a dust particle and a defect on the surface of a card. CONSTITUTION:The following are arranged respectively: a first photodetector 71, for information playback use, and a second photodetector 81, for information playback use, which photodetect beams of reflected light from two light spots formed in a track on an optical card by means of an optical beam for information playback use. A counting operation is started on the basis of the output of a pit detection by means of the first preceding photodetector 71 for information playback use; a speed data detection means is installed by using a counter group 79 which sequentially measures the time up to a pit detection by means of the second posterior photodetector 81 for information playback use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information by providing means for detecting relative speed between an optical head and a recording medium such as an optical card.

[0002]

2. Description of the Related Art In an optical information recording / reproducing apparatus using an optical card as a recording medium, an optical card having a plurality of tracks parallel to each other and an optical head for optically recording / reproducing information on / from the optical card. And are relatively moved in the track direction to record / reproduce information.

Generally, in an optical information recording / reproducing apparatus using a disc type recording medium such as an optical disc, information is recorded / reproduced by a rotational movement, so that the relative moving speed of the recording medium and the optical head is relatively stable. However, since the optical information recording / reproducing apparatus using the optical card reciprocates to record / reproduce information, the relative moving speed of the optical card and the optical head has a relatively large fluctuation. Therefore, in such an optical recording / reproducing apparatus, this movement speed fluctuation must be taken into consideration when recording / reproducing information.

To solve this, for example, Japanese Patent Laid-Open No. 61-61
In Japanese Patent No. 153834, a clock generation pattern is prerecorded in each track in an optical card,
When reciprocating the optical card in the track direction, this pre-record pattern is detected to generate a clock signal,
Information is recorded in synchronization with this clock signal. Further, in Japanese Patent Laid-Open No. 1-256069, a relative movement speed between an optical head and an optical card is recorded by a signal from a means for conveying the optical card, for example, a recording signal by an output clock of a linear coder attached to a linear motor of the conveying means. It has been proposed to correct the playback signal.

[0005]

However, in the above-mentioned conventional optical information recording / reproducing apparatus, in the former case, the information is recorded based on the clock pattern in the optical card. Although there is an advantage that information can be accurately recorded even if speed irregularities occur in the transportation means, on the other hand, if the pattern cannot be detected due to scratches or dust attached to the optical card surface, the clock signal at that part However, there is a problem that it becomes impossible to record information.

In the latter case, a linear encoder is required for the linear motor of the optical card transporting means, and there is a problem that the apparatus becomes expensive. Further, as described above, a linear encoder is often used that has an accuracy of outputting one clock for every 200 μm of the movement amount of the optical card. Low. In addition, there is a problem in that a high-accuracy linear encoder is required to increase the accuracy of speed fluctuation detection, and the extra device becomes expensive.

The present invention has been made in view of the above-mentioned problems, and the relative movement speed of the optical recording medium and the optical head is
An object of the present invention is to provide an optical information recording / reproducing apparatus that does not require a special pre-record pattern for each track, can be configured without being affected by dust and scratches on the card surface, and can make the apparatus inexpensive. And

[0008]

In order to achieve the above object, the present invention comprises a light spot forming means for forming two light spots by an information reproducing light beam in a track extending direction on an optical recording medium. In the optical information recording / reproducing apparatus, a first information reproducing light receiving element is provided at a position on a photodetector that receives two light spots formed on a track on the optical recording medium by the information reproducing light beam. Second information reproducing light receiving elements are respectively arranged, and the optical recording medium and the optical head are moved relative to each other based on the output of the first information reproducing light receiving element and the output of the second information reproducing light receiving element. Speed detecting means for detecting the speed is provided, and the speed detecting means is based on the pit detection pulse from the first information reproducing light receiving element and the pit detecting pulse from the second information reproducing light receiving element. It is constituted by the time interval measuring means for measuring a time interval between two pit detection pulse.

[0009]

As described above, in the optical information recording / reproducing apparatus of the present invention, two information reproducing light receiving elements for one track are provided on the photodetector, and one pit on the track is formed by two.
The count means is reset by each pulse of the preceding binarized signal, and the count value is latched by the latch means by each pulse of the subsequent binarized signal corresponding thereto. Therefore, the output of the latch means can be detected with the accuracy of the pit unit on the optical card, which is a value proportional to the time during which the optical card passes the length between the two information reproducing light receiving elements, that is, the moving speed of the optical card. ..

Further, with respect to defects such as dust and scratches on the optical card, since they appear in the form of signals in both the preceding information reproducing light receiving element and the following information reproducing light receiving element, like the pit, This makes it possible to detect speed fluctuations. Further, since the moving speed of the optical card is detected by the recorded data on the optical card without providing the linear scale, the linear scale or the like is unnecessary and the apparatus can be made inexpensive.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to an embodiment of the present invention.
Shows the structure of the optical head in the optical information recording / reproducing apparatus of the first embodiment, and FIG. 2 shows the positional relationship between the recording light beam spot formed on the optical card and the spot formed by the diffracted light of the reproducing light beam. 3 shows a spot image of the recording light beam and a spot image of the 0th-order diffracted light and the 1st-order diffracted light of the reproduction light beam projected on the photodetector 17, and FIG.
Shows a block diagram of the speed fluctuation detecting circuit, and FIG. 5 is a time chart for explaining the operation of the speed fluctuation detecting circuit.

As shown in FIG. 1, in the optical head 10 in the optical information recording / reproducing apparatus of the first embodiment, the light beam generated by the semiconductor laser 1 which is a light source for information recording is collimated by the collimating lens 2 and is a substantially parallel beam. Becomes Further, the parallel beam is shaped into a substantially circular shape by reducing only the elliptical long-axis direction component in the shaping prism 3, and then the parallel beam is adjusted by the circular diaphragm 4 so that the spot size becomes a predetermined value on the recording medium. The diameter is reduced and the light enters the polarization beam splitter 5.

The circular beam for recording is the semiconductor laser 1
Due to the property of (1), most of the beam is reflected by the reflection surface of the polarization beam splitter 5 and is incident on the optical axis of the objective lens 6. This light is condensed by the objective lens 6 to form a circular spot on the optical card 7, the energy density is locally increased, and the recording layer of the optical card 7 is thermally irreversibly changed to form a recording pit. .

On the other hand, a light beam emitted from a semiconductor laser 40 provided as a light source for reproducing information separately from the semiconductor laser 1 passes through a collimating lens 9 to become a substantially elliptical parallel beam, and a shaping prism 41. At, only the short-axis component of the ellipse is enlarged and shaped into a substantially circular shape. The circular beam is further narrowed down by the circular diaphragm 42 so that the spot size on the recording medium becomes a predetermined size, and enters the plano-concave cylindrical lens 43.

This light beam is refracted by the plano-concave cylindrical lens 43 in only one direction in the plane perpendicular to the optical axis, and becomes a beam that diverges slightly in that direction. Further, it is split by the diffraction grating 44 into 0th-order diffracted light and two 1st-order diffracted lights. At this time, the cylindrical lens 43
The diffraction grating 44 and the diffraction grating 44 are arranged at positions such that the diverging direction of the light beam by the cylindrical lens 43 and the diffraction direction by the diffraction grating 44 are substantially orthogonal to each other.

Since the three light beams divided by the diffraction grating 44 are almost P-polarized components due to the property of the semiconductor laser, most of the components pass through the polarization beam splitter 5 and are condensed by the objective lens 6. Then, three spots are formed on the optical card 7. Since the light beam is originally diverged by the cylindrical lens 43, each light beam spot formed on the optical card 7 is also expanded and formed in the diverging direction.

FIG. 2 is a diagram showing the positional relationship between the recording light beam spot 23 formed on the optical card 7 and the spots 25a, 25b, 25c formed by the diffracted light of the reproducing light beam. These beam spots are arranged such that the recording light beam spot 23 is located between the spot 25a of the 0th-order diffracted light of the reproduction light beam and either one of the spots 25b or 25c of the 1st-order diffracted light.

This arrangement is used when assembling and adjusting the optical head.
This is adjusted by giving a relative angular difference between the optical axis of the recording light beam and the optical axis of the reproducing light beam before entering the objective lens 6. Since the cylindrical lens 43 is arranged so that the expanding directions of the reproducing light beam spots 25a, 25b, 25c on the optical card 7 are substantially orthogonal to the extending direction of the tracks, information of a plurality of tracks is simultaneously recorded. Obtainable.

Spot 2 due to the diffracted light of the reproduction light beam
5a, 25b and 25c are specularly reflected on the optical card 7 in a state where the light amount is modulated depending on the presence or absence of the track guide 21 and the pit 22 on the optical card 7. These reflected lights pass through the objective lens 6 in the opposite direction and are guided to the polarization beam splitter 5 in the state of substantially parallel light. Since these reflected lights are specularly reflected on the optical card 7, they retain almost P-polarized light, and most of the components pass through the polarization beam splitter 5 and are guided to the reflection mirror 14.

After being reflected by the reflecting mirror 14, it is condensed by the condenser lens 15 and further divided by the half mirror 16, and the light receiving surfaces of the signal reproducing and tracking photodetectors 17 and the focusing photodetectors 18 are collected. Respectively, and the image of the spot is enlarged and projected. As mentioned above,
The reproduction light beam is incident on the objective lens 6 at a position decentered from the optical axis, and so-called off-axis focus detection is performed. The focus photodetector 18 is provided with, for example, a two-divided light receiving element, and is configured to detect the movement of the image of the reproduction light beam spot due to the focus shift.

FIG. 3 is a diagram showing the spot image of the recording light beam and the spot image of the 0th-order diffracted light and the 1st-order diffracted light of the reproduction light beam projected on the photodetector 17. On the photodetector 17, signal reproducing light-receiving elements 51, 52, 53 and tracking light-receiving elements 61, 62, 63, 64 are arranged, and an enlarged and projected image of the optical image of the reproducing light beam is further arranged. When 25d, 25e, and 25f are imaged at appropriate positions on these light receiving elements without any track deviation and focus deviation, the spot 25 formed by the first-order diffracted light is formed.
Signal reproducing light-receiving elements 54, 55, and 56 are provided at positions where the image 25e corresponding to b is formed.

Tracking light receiving elements 61, 62 and 6
Reference numerals 3 and 64 detect a change in the position of the image of the track guide due to a track shift as a change in the amount of received light, and generate a tracking error signal. Light receiving elements 51, 52 for signal reproduction
At 53 and 54 or at 54, 55 and 56, the presence or absence of pits for three tracks is detected by a change in the light amount, and a reproduction signal is output.

At the time of recording information, as shown in FIG. 2, when the optical card 7 is moving in the direction of arrow a (forward direction), the pit 2 formed by the recording light beam spot 23 is formed.
2 moves toward the spot 25c by one of the first-order diffracted lights of the reproduction light beam, and when the pit 22 reaches the position of the spot 25c, the signal reproduction light-receiving element 52 on the photodetector 17 is detected. Since the light amount changes and the reproduced signal is output, the reproduced signal immediately after recording is obtained,
The verify operation is performed based on this reproduction signal.

Further, the moving direction of the optical card 7 is reversed,
When moving in the direction of arrow b (reverse direction), the pits 22 formed by the recording light beam spot 23 are
The pit 22 moves to the spot 2 where the pit 22 moves toward the spot 25b due to the other first-order diffracted light of the reproduction light beam.
When the position 5b is reached, a light amount change occurs in the signal reproduction light-receiving element 55, and a reproduction signal immediately after recording can be obtained from this light amount change, and a verify operation is performed based on this reproduction signal.

Therefore, regardless of whether the optical card 7 is moved in the forward direction or in the reverse direction, a reproduction signal can be obtained immediately after recording. That is, regardless of the moving direction of the optical card that reciprocates with respect to the optical head, it is possible to obtain a reproduction signal immediately after recording and perform a verify operation for checking the quality of recording.

Next, the speed fluctuation detecting circuit 70, which is a feature of the present invention, will be described with reference to FIG. In FIG.
Reference numeral 71 is a light receiving element for signal reproduction provided on the photodetector 17, and corresponds to, for example, 55. Reference numeral 81 is also a signal reproduction light receiving element provided on the photodetector 17, and corresponds to, for example, 52. Reference numerals 72 and 82 denote I / V converters that convert the signals received by 71 and 81 into current-voltage conversion, and 73 and 8 respectively.
Reference numeral 3 is a binarization circuit for converting the outputs of 72 and 73 into a binarized signal at a reference level.

Reference numeral 78 is a selector for switching whether the outputs of the binarization circuits 73 and 83 are supplied to the edge detection circuits 74 and 84, respectively, by a movement direction instruction signal according to the card movement direction. 74 and 84 are selectors 78, respectively
It detects the rising edge and the falling edge of the binarized signal output from the digital signal, and is composed of a D flip-flop and a gate. The edge detection circuit 74 includes D flip-flops 74a and 74b and a gate 74c,
It is composed of 74d. The edge detection circuit 84 has the same configuration.

The binarized signal output from the selector 78 is supplied with the binarized signal from the preceding light receiving element (for example, the light receiving element 55 in the forward direction) to the edge detecting circuit 74, and the edge detecting circuit 74 is supplied. A binarized signal from a light receiving element (for example, the light receiving element 52 in the case of the forward direction) of the subsequent row is supplied to 84. Reference numeral 75 is a counter that counts up for each falling edge detection signal from the edge detection circuit 74. A decoder 76 supplies a reset signal to one of the speed fluctuation measurement counter groups 79 for each rising edge detection signal from the edge detection circuit 74 in accordance with the output value of the counter 75.

That is, for example, when the output value of the counter 75 is 0 and the preceding binarized signal rises, a reset signal is output to the counter 79a of the speed fluctuation measurement counter group 79, and the output of the counter 75 is output. If the value is 1,
At the rising edge of the preceding binarized signal, the reset signal is output to the counter 79b in the speed fluctuation measuring counter group 79. Reference numeral 85 is a counter that counts up for each falling edge detection signal from the edge detection circuit 84.

A decoder 86 supplies an output enable signal to one of the speed fluctuation measuring counter groups 79 in accordance with the output value of the counter 85. That is, for example, when the output value of the counter 85 is 0, the output enable signal for the counter 79a in the speed fluctuation measurement counter group 79 becomes active, and when the output value of the counter 85 is 1, it is for speed fluctuation measurement. The output enable signal for the counter 79b of the counter group 79 becomes active.

Reference numeral 79 is a speed fluctuation measuring counter group,
Each of the counters 79a to 79p constituting this is
It is a three-state type counter that performs counting operation with a high frequency clock (not shown), is reset by a reset signal from the decoder 76, and outputs the contents of the counter only when the output enable signal from the decoder 86 is active. Reference numeral 77 is a latch that latches the output value from the speed fluctuation measurement counter group 79 with the rising edge detection signal from the edge detection circuit 84. In addition,
In FIG. 4, edge detection circuits 74 and 84, a counter 75,
Although not shown, the same high-frequency clock is supplied to each of the counters 85 and the speed fluctuation measuring counter group 79 and the latch 77, though not shown.

FIG. 5 is a time chart for explaining the operation of the block diagram of FIG. In this example, the distance between the reproducing light receiving elements on each track in FIG. 3, for example, the light receiving element 5
The interval of 2,55 corresponds to 80 μm on the optical card, and the minimum pit interval on the optical card is 6 μm. The distinction of the pulse of the preceding binarized signal to the pulse of the subsequent binarized signal is realized by numbering each pulse. Since there can be up to 14 (80/6) pits on the optical card at 80 μm,
The number of bits required for this numbering is 4 bits (2 4 =
16 ways).

This numbering is performed by the counters 75 and 85 shown in FIG.
Therefore, the number of bits of these counters may be 4 bits. Therefore, the decoders 76 and 86 are 4-input 16-output decoders, and the counters of the speed fluctuation measuring counter group 79 are 16 (79a to 79p). Each of the counters 75 and 85 is initialized to 0 at the head of the track to be read (or the head of the selector). Here, a case of reproducing information in the forward direction will be described.

The photoelectric conversion output corresponding to the pit is I / V converted by the light receiving element 52 (81 in FIG. 4) of FIG. 3 and binarized by the binarization circuit 83 to the reference level in FIG. The binarized signal shown is output to the selector 78. The output of the binarized signal which is received by the following light receiving element 55 (71 in FIG. 4) and binarized by the binarization circuit 83 at the reference level is shown in FIG.
As shown in (b), a signal having a similar waveform is output with a delay of 80 μm.

Therefore, the binarized signal from the preceding light receiving element is input to the edge detection circuit 74 by the selector 78, and the binarized signal from the light receiving element in the subsequent row is input to the edge detection circuit 84. To do. First, FIG. 5 (c)
When the first pulse of the preceding binarized signal is input to the edge detection circuit 74 as shown in FIG. 5, the value of the counter 75 at this time is the initial value 0 as shown in FIG. The decoder 76 resets the speed fluctuation measuring counter 79a as shown in FIG. 5 (e).

The counter 75 counts up to 1 at the falling edge of the first pulse. Next, when the second pulse is input to the edge detection circuit 74, the value of the counter 75 is 1. Therefore, the speed fluctuation measuring counter 79
b is reset and the counter 75 counts up to 2 at the falling edge of this pulse.
The same operation is performed each time a pulse is input thereafter. 16 pulses are input and the speed fluctuation measurement counter 79p
Since the counter 75 has 4 bits when it is reset up to 0, it becomes 0 again and returns to the speed fluctuation measuring counter 79a, and the same operation is repeated.

When the optical card moves about 80 μm, a pulse corresponding to the pulse of the preceding binarized signal appears on the light receiving element in the subsequent line. When the first pulse of the binarized signal in the subsequent row is input to the edge detection circuit 84, the value of the counter 85 is 0 at the initial value as shown in FIG. Since the output of the speed fluctuation measuring counter 79a is enabled by 86, FIG.
Latch 77 at its rising edge as shown in FIG.
The value of the speed fluctuation measuring counter 79a is latched in and is output from the latch 77 as shown in FIG.

At the falling edge of this pulse,
The counter 85 counts up and becomes 1. Next, when the second pulse is input to the edge detection circuit 84, since the value of the counter 85 is 1, the output of the speed fluctuation measurement counter 79b is latched by the latch 77 and output. Thereafter, the same operation is repeated each time a pulse of the binarized signal in the subsequent row is input.

When the movement of the optical card is in the reverse direction, the selector 78 may switch the binarized signals input to the edge detection circuits 74 and 84 so as to be opposite to those in the forward direction. Although the above description has been made with respect to the light receiving elements 52 and 55, it goes without saying that other light receiving elements 51 and 54 or light receiving elements 53 and 56 can be used for each track.

As described above, each of the speed fluctuation measuring counters is reset by each pulse of the preceding binarized signal, and the count value is latched in the latch 77 by each pulse of the subsequent binarized signal. As such, the output of the latch 77 will be the time for the optical card to pass a length of 80 μm.

That is, the output of the latch 77 has a value proportional to the speed of the optical card. Since the output of the latch 77 is output for each pit on the optical card, an accuracy of about 6 μm to about a dozen μm on the optical card can be obtained, which is finer than about 200 μm in the case of the conventional linear encoder. It is possible to detect speed fluctuations. Also, for defects such as dust and scratches on the optical card, since it appears in the form of a signal on both the preceding light receiving element and the following light receiving element, it is possible to detect the speed fluctuation by this as in the case of the pit. it can.

If the speed fluctuation can be detected in this way,
It is easy to carry out recording and reproduction of information more accurately based on this result. Regarding recording of information, for example, it is as follows. Since the optical information recording / reproducing apparatus as a premise can reproduce the information of three tracks by one scanning as shown in FIG. 3, the information of the tracks before and after the track to be recorded can be reproduced. If any one of the tracks has already been recorded, the speed fluctuation may be detected by the reproduction binarized signal from the track to correct the information recording signal.

When there is a circuit shown in FIG. 4 corresponding to each track and there are a plurality of outputs, for example, an average value may be used. Further, in the case of a virgin card, a reproduced binary signal from the test track may be used. This test track is for testing the device, so data is written at the minimum pit interval,
It may also contain initial information about the card as it was manufactured.
When the data is recorded for the first time on a track separated from the test track, for example, the speed variation data obtained on the test track may be recorded in a memory or the like and the data may be used.

Here, the moving speed of the optical card is 640 mm.
/ Sec, and the cycle of the high-frequency clock supplied to each of the speed fluctuation detection counters is 640 kHz.
(One cycle is 1.5625 μsec.) Now, assuming that the speed fluctuation is 0, the time when the optical card moves by 80 μm is 125 μsec, so the count value of the speed fluctuation measuring counter is 125/1. 0.5625 =
It becomes 80 (50H). Further, it is assumed that the length of 1τ which is the reference of the recording data is 4 μm (6.25 μsec).

If the output of the latch 77 is 52H due to the binarized signals from the tracks before and after the track to be recorded, the optical card moving speed will be slightly slower, and the recording signal 1τ will be slightly narrowed for recording. To do. Further, if the output of the latch 77 is 4EH, the optical card moving speed is slightly high, and therefore 1τ of the recording signal is slightly widened for recording. That is, 1τ is converted to 6.25 μse
It is recorded as c × 50H / 4EH = 6.41 μsec. In this way, information can be recorded accurately.

As for the reproduction of information, the pit clock required when the recording data is recorded by the MFM or the modulation method that requires the generation of the self clock such as (2,7) modulation. The speed fluctuation detection result may be given to the generation circuit. That is, the pit clock generation circuit may calculate the basic cycle of the bit clock based on the output value of the latch 77, and generate the bit clock based on this basic cycle.

In the above description, the light beam of one semiconductor laser 40 is generated through the diffraction grating 44 to generate two light beams so that the two light beams form two spots in the track extending direction. I have to. The present invention is not limited to this, and for example, two semiconductor lasers may be used to form two spots for each beam in the track extending direction without using a diffraction grating.

In this case, it is desirable that the two semiconductor lasers have the same characteristics. Therefore, for example, one having two semiconductor lasers formed on the same chip may be used. Also, the beam emitted in the back direction of one semiconductor laser 40 may be used together with the beam emitted in the forward direction so that two spots are formed in the track extending direction without using a diffraction grating. .. The present invention is not limited to the card-shaped recording medium, but can be applied to an information recording / reproducing apparatus having at least an information reproducing function using a disc-shaped recording medium.

[0049]

As described above, in the optical information recording / reproducing apparatus of the present invention, two information reproducing light receiving elements for one track are provided on the photodetector, and one pit on the track is detected twice. The counting means is reset by each pulse of the preceding binarized signal to start the counting operation, and the count value is latched in the latch means by each pulse of the binarized signal of the subsequent row corresponding thereto. Therefore, the output of the latch means is the time in which the recording medium passes the length between the two information reproducing light receiving elements, that is, the value proportional to the moving speed of the recording medium is the accuracy of the pit unit on the recording medium. Can be detected with.

Further, dust on a recording medium such as an optical card,
Even with a defect such as a scratch, since it appears in the form of a signal on both the preceding information reproducing light-receiving element and the subsequent information reproducing light-receiving element, it is possible to detect the speed fluctuation by this similarly to the pit. Further, since the moving speed of the recording medium is detected by the recording data on the recording medium without providing the linear scale, the linear scale or the like is unnecessary and the apparatus can be made inexpensive.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of an optical head in an optical information recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a positional relationship between a spot of a recording light beam formed on an optical card and a spot of diffracted light of a reproduction light beam.

FIG. 3 is an explanatory diagram showing a spot image of a recording light beam and a spot image of a 0th-order diffracted light and a 1st-order diffracted light of a reproducing beam projected on a photodetector.

FIG. 4 is a block diagram showing a configuration of a speed fluctuation detection circuit.

FIG. 5 is a time chart diagram for explaining the operation of the speed fluctuation detection circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser 2 ... Collimating lens 3 ... Shaping prism 4 ... Aperture 5 ... Polarization beam splitter 6 ... Objective lens 7 ... Optical card 10 ... Optical head 17 ... Photodetector 40 ... Semiconductor laser 43 ... Cylindrical lens 44 ... Diffraction grating 70 ... Velocity fluctuation detection circuit 71, 81 ... Reproducing light receiving element 73, 83 ... Binarization circuit 74, 84 ... Edge detection circuit 75, 85 ... Counter 76, 86 ... Decoder 77 ... Latch 79 ... Counter group

Claims (4)

[Claims] 1. An optical information recording / reproducing apparatus comprising a light spot forming means for forming two light spots by an information reproducing light beam in a track extending direction on an optical recording medium. The first information reproducing light receiving element and the second information reproducing light receiving element are respectively arranged at the positions on the photodetector for receiving the two light spots formed on the track on the optical recording medium. Speed detecting means is provided for detecting the relative moving speed of the optical recording medium and the optical head based on the output of the first information reproducing light receiving element and the output of the second information reproducing light receiving element. Is for measuring the time interval between two pit detection pulses based on the pit detection pulse from the first information reproduction light receiving element and the pit detection pulse from the second information reproduction light receiving element. The optical information recording and reproducing apparatus, characterized in that it consists of interval measuring means. 2. The first information reproducing light receiving element and the second information reproducing light receiving element.
2. The optical information recording / reproducing apparatus according to claim 1, wherein a plurality of the information reproducing light receiving elements are arranged at positions on the photodetector corresponding to a plurality of tracks on the optical recording medium. apparatus. 3. The output of the first light-receiving element for information reproduction and the output of the second light-receiving element for information reproduction are selectively supplied to the speed detecting means according to the moving direction of the optical recording medium. 3. The optical information recording / reproducing apparatus according to claim 1 or 2, further comprising selection means for performing the above. 4. The speed detecting means includes first numbering means for numbering the pit detection pulses from the first information reproducing light receiving element, and pits from the second information reproducing light receiving element. It comprises a second numbering means for numbering the detection pulses, a plurality of counting means, and a latching means, and one counting means of the plurality of counting means outputs the first numbering means. Is initialized based on the output of the second numbering means, and the count value of one counting means of the plurality of counting means is latched by the latch means based on the output of the second numbering means. The optical information recording / reproducing apparatus according to claim 1 or 2.