JPH0321992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image recording and reproducing apparatus such as an electronic camera that magnetically or optically records and reproduces image information on a disk-shaped recording medium, and particularly relates to an image recording and reproducing apparatus such as an electronic camera that records and reproduces image information magnetically or optically on a disk-shaped recording medium. The present invention relates to a means for recording and reproducing data dividedly into a plurality of tracks.

In an image recording and reproducing device such as an electronic camera, which has an imaging section that photoelectrically converts image information to obtain a video signal and a recording section that records the video signal on a recording medium such as a magnetic disk, a magnetic disk device is used as the recording section. When used, the following restrictions apply. First of all, when integrating the imaging section and the recording section, it is necessary to downsize the recording section, which requires the use of a magnetic disk with a small diameter. However, under the same recording conditions, the smaller the diameter of the magnetic disk, the more disadvantageous it becomes in terms of recording wavelength.

Next, when recording information on a disk-shaped recording medium, there are two recording methods: forming concentric tracks or forming spiral tracks. If the main information is a video signal,
When the reproduced image is a still image, concentric tracks are usually formed, and when the reproduced image is a moving image, spiral tracks are usually formed. In other words, when focusing on still images, it is desirable to record field or frame-by-frame images on concentric tracks, and when focusing on moving images, it is desirable to record vertical synchronization signals so that the recording position is aligned in a straight line in the radial direction of the disk. It is desirable to form a track in a spiral shape. In the case of concentric tracks, a still image is obtained by repeatedly regenerating the same track, and in the case of a spiral track, a moving image is obtained by reproduction by normal tracking. This is because recording moving images on concentric tracks and reproducing still images on spiral tracks requires a so-called track jump operation that instantly moves the head to an adjacent track, so a more complex head drive mechanism is required. This is to become. Therefore, it mainly records still images,
It is desirable to form concentric tracks on a magnetic disk for an electronic camera, where it is difficult to incorporate a complicated mechanism due to miniaturization, and to have a structure in which the same track is repeatedly reproduced.

By the way, when trying to obtain a still image by repeatedly playing back one track recorded concentrically,
It is sufficient to record at least one field of video signals on one track, but in order to prevent a decrease in vertical resolution, it is necessary to record two fields, that is, one frame of signals. Furthermore, in order to obtain a complete still image using the NTSC system, video signals for four fields are required due to the relationship between color signals.

On the other hand, as mentioned above, in order to reduce the size of a magnetic disk device used in an electronic camera device, a recording medium with an innermost circumference of the recording area of the disk of about 30φ is used. in this case,
In field recording, the relative velocity is 5.6 m/sec, and in frame recording, the relative velocity is 2.8 m/sec. In order to ensure resolution in the horizontal direction, the lower the relative speed, the more short wavelength recording becomes necessary, but there is a limit to the recording wavelength determined by the characteristics of the recording medium and head. If you want to record a signal with a relative speed of 2.8 m/sec and an upper limit of the band of about 10 MHz, the required shortest recording wavelength will be 0.28 μm, but considering the current head processing technology and media characteristics, this value is not possible. is extremely difficult. Considering this, the video signal recorded on one track must be one field. Therefore, when recording and reproducing frames on such a small-diameter disk, the configuration is such that one frame still image is obtained by alternately reproducing two tracks in which one field is recorded on one track.
Furthermore, in order to obtain a complete still image in the NTSC system, as mentioned earlier, a 4-field video signal is required, so the number of tracks required to compose one still image is determined accordingly. The number of tracks will also increase to four.

To summarize what has been said so far, (1) In order to avoid track jump operations, it is sufficient to record information for one still image on one track using concentric tracks.

(2) However, when trying to obtain high image quality while reducing the diameter of the disk, it is difficult to record and reproduce the information of one frame of still image on one track due to the recording wavelength, and in the end, multiple tracks are required. There is no choice but to record the information separately.

(3) For this reason, track jumps must be performed as long as one head is used for recording and playback.

There is a problem.

The above are the drawbacks of the conventional device when a single head is used, but the following drawbacks also exist when a multihead is used.

FIG. 1 shows a conventional multihead configuration.
1' is the core of the first head, and 2' is a head gap provided on this core. Further, 3' is the core of the second head, and 4' is a head gap provided on this core. 5' is a shield material separating the first head from the second head. In order to simplify the explanation,
The widths of core 1', core 3', and shield 5' are all W.
Suppose that

The biggest problem with multiheads of this type of structure is crosstalk during recording. In the case of digital audio tape recording (DAT), since it is a digital recording, the above A can be set to about 100 μm by determining the optimal head structure, but in video band recording, even if A is about 250 μm, cross-linking may occur. The talk is large and the image quality deteriorates.
Therefore, if a video signal with low crosstalk is to be recorded with a narrow track pitch, it is difficult to use the head configuration shown in FIG. Therefore, it is conceivable to employ separate heads H1 and H2 having a configuration as shown in FIG. However, although crosstalk is reduced with the head configured as shown in Figure 2, unless a head pad is used, the surface pressure between the multiple heads and the recording medium is insufficient, resulting in spacing loss, making it difficult to achieve stable recording. Unable to play. Note that when using a recording medium such as a floppy disk for a long time, it is not preferable to use a head pad or the like.

It should be noted that conventional apparatuses have the disadvantage that there is a large difference in recorded information between the inner and outer circumferences of the disk, whether single-head or multi-head. For example, assuming a disk with an outermost track of 50φ and an innermost track of 30φ, the maximum and minimum track lengths are 5:
The ratio is 3. Therefore, there is a problem in that the performance of the entire apparatus is limited by the recording wavelength allowed on the innermost track.

The present invention has been made based on these circumstances, and its purpose is to record and reproduce image information by dividing it into a plurality of tracks without requiring the head to perform complicated operations such as track jumps. Moreover, it is possible to stably obtain still images with high resolution without problems such as crosstalk, and the performance of the entire device is not limited by the recording wavelength allowed on the innermost track of the disk. The purpose of the present invention is to provide a recording/playback device.

In the present invention, the recording/playing head is divided into a recording/playing head dedicated to the outer track and a recording/playing head dedicated to the inner track, and these heads are installed in opposite radial directions across the center of rotation of the disk. The present invention is characterized in that the above object is achieved by dividing image information into a plurality of tracks, recording them, and reproducing them.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

Figures 3a and 3b are a plan view and a side view showing the head configuration of an embodiment of the present invention, showing the basic configuration when recording n-frame still images using two heads. It shows.

In the figure, 1 is a magnetic disk, 2 is a support member for supporting and fixing the head, and 3 is a first recording/reproducing head for recording and reproducing information in a first recording area M provided on the outer periphery of the magnetic disk. , 4 is a second recording/reproducing head for recording and reproducing information in a second recording area N provided at the inner peripheral portion of the magnetic disk. The first recording/playing head 3 and the second recording/playing head 4 are integrally attached to the support member 2, and the distance H between the heads is defined as the distance a from the center of the disk to the outermost recording track OT1. When b is the distance from the center of the disk to the innermost track IT1, it is expressed as H≈a+b.

When starting recording on an unrecorded magnetic disk, the first recording/reproducing head 3 starts recording from the outermost track OT1, and the second recording/reproducing head 4 starts recording from the innermost track IT1. A new track is formed by sequentially moving the head support member 2 in the direction of the arrow. As a means for moving the support member 2, various well-known means can be considered, such as a means for moving it with a screw, but as a head actuator for recording still images, it is not necessary to move the head at such a high speed, so it is simple. Any structure is fine. Note that the distance the head is moved by the actuator is 1/2 compared to the case of 1 head.
That's a good thing.

FIG. 4 is a block diagram showing the configuration of a drive control system of this apparatus using the head configured as shown in FIGS. 3a and 3b.

In FIG. 4, reference numeral 7 denotes an imaging optical system that forms a subject image on the light receiving surface of the solid-state image sensor 8. Note that a shutter may be inserted between the element 8 and the imaging optical system 7. The solid-state image sensor 8 photoelectrically converts the subject image formed on the light-receiving surface and extracts it as an electrical signal. Reference numeral 9 denotes a synchronization signal generation circuit which not only applies drive pulses to the solid-state image sensor 8 but also generates a synchronization signal for the TV signal. 10 is a process circuit for creating a TV signal based on the image signal output read from the solid-state image pickup device 8, and is composed of a preamplifier, a color separation circuit, a γ correction circuit, a color encoder, and the like.
A video signal processor 11 converts the TV signal output from the process circuit 10 into a signal suitable for magnetic recording. For example, as is well known, signal processing such as luminance signal low carrier wave FM recording, low frequency conversion color signal recording, APC color process, etc. used in VTRs is performed. In addition, the video signal processor 11 receives the playback signal.
Also included is circuitry for demodulating to TV signals. 12
is a monitor made of CRT, liquid crystal, etc., and in electronic camera equipment, it is installed either integrally with the main body or separately in order to display the reproduced video signal as an image. Reference numeral 13 denotes a head switching circuit which is particularly added in this embodiment. This head switching circuit 13 is connected to the outer track group of the magnetic disk 1.
The first recording/playback head 3 records to OT1 to OTn.
and the second track group IT1 to ITn for recording.
This is for switching the recording/reproduction signal input to the recording/reproduction head 4 of the recording/reproducing head 4. That is, after the first recording/reproducing head 3 records the video signal of the first field, switching to the second recording/reproducing head 4 continues to record the video signal of the second field. In this way, one frame per track and one field is recorded. The switching signal for the head switching circuit 13 is generated from the VD signal generated from the synchronizing signal generating circuit 9. In order to align the recording positions of the vertical synchronization signals, a signal or marker indicating the reference position on the disk 1 is detected, and the disc is adjusted so that the detected signal and the vertical synchronization signal generated from the synchronization signal generation circuit 9 match in phase. It is necessary to control the rotation of the drive motor 14. 1
5 is a motor drive circuit for driving the disk drive motor 14. This circuit 15 has a phase synchronization control loop for controlling the disc motor 14 in phase synchronization in addition to a speed control loop for controlling the disc motor at a constant speed. The rotational phase of the disk is detected by a disk rotational phase detector 16, and a detection signal of one pulse per rotation is sent out. The reference signal for synchronization is the vertical synchronization signal generated from the synchronization signal generator 9 as described above. The difference between the phase angle of the reference signal and the rotational position angle of the disk is detected by the phase detector in the motor drive circuit 15, and a torque proportional to the difference and in a direction to eliminate the phase difference is generated. generate. In this manner, the rotation of the disk is controlled so that it is phase synchronized with the vertical synchronization signal. As a result, recording can be performed such that the recording positions of the vertical synchronizing signals are aligned in a straight line in the radial direction of the disk.

During reproduction, frames are reproduced by alternately switching and extracting the signal reproduced by the first recording/reproducing head 3 and the signal reproduced by the second recording/reproducing head 4. . In this case, since disk 1 is rotating in phase synchronization with the vertical synchronization signal, the recording position angle of the vertical synchronization signal on the track and the synchronization signal generator are generated.
The phase difference with the VD signal is constant. Therefore
One frame of the TV signal, which is reproduced by switching between heads 3 and 4 using a head switching signal generated based on the VD signal, is free from synchronization disturbance.

In this way, in this embodiment, frame recording and playback can be performed on two tracks by the switching operation of the head switching circuit, and there is no relative positional deviation between the first and second recording/playback heads 3 and 4. , tracking control is much easier than in the case where the two heads 3 and 4 are controlled independently.

By the way, in order to improve the resolution of the reproduced image, it is necessary to widen the band of the recording signal. As a means for this purpose, a method is known in which the luminance signal and the color signal are separated and recorded on separate tracks.

FIG. 5 is a block diagram showing the configuration of a drive control system in a second embodiment when the present invention is applied to a separate chroma type device. Note that the same parts as in FIG. 4 are given the same reference numerals and detailed explanations will be omitted. As in the first embodiment, the subject image formed by the imaging optical system 7 is converted into an electrical signal by the solid-state imaging device 8 and supplied to the process circuit 20. The process circuit 20 generates a luminance signal and a color signal to which a synchronization signal has been added, and supplies these signals to a video signal processing circuit 21. During recording, the video signal processing circuit 21 separately FM modulates the luminance signal and the color difference signal and supplies them to the first head 3 and the second head 4 for recording.

During playback, the luminance signal and color difference signal are each demodulated and then converted into a TV signal by an output matrix circuit and output to the monitor device 12 for display. When applied to a separate chroma system in this way, chroma color can be prevented and horizontal resolution can be improved.

The explanation so far has been about the first recording/playback head, which performs recording and playback on the outer circumference of the medium, and the second recording/playback head, which performs recording and playback on the inner circumference of the medium.
In this case, a video signal is supplied to both of the recording and reproducing heads, and only the recording and reproducing of the video signal is performed. It is also possible to supply a sub-information signal such as a compressed audio signal or a tracking control signal, and use the inner or outer circumference of the recording medium as a sub-information signal track forming section. This point will be explained below.

As is well known, higher density recording can be achieved by narrowing the track width and narrowing the track pitch, but in this case it is necessary to perform precise tracking. One known means for performing such precise tracking is to record a pilot signal for tracking by subjecting the main information signal to frequency division or time division multiplexing. However, when such a measure is taken, there are many undesirable problems such as a decrease in the bandwidth usage area due to the superimposition of the pilot signal, generation of a beat between the main information signal and the pilot signal, and influence on adjacent tracks. According to the structure of the present invention, the first recording/playing head 3 that performs recording/reproduction on the outer circumference of the medium and the second recording/playback head 4 that performs recording/reproduction on the inner circumference of the medium are integrally supported. Therefore, if tracking control is performed on either head, the other head will also be tracked. In this case, since the two heads 3 and 4 are sufficiently separated, the influence of the pilot signal will not be exerted on the head that is not used for recording and reproducing the pilot signal. Therefore, for example, if the outer circumference of the recording medium is used exclusively as a recording section for video signals, and the inner circumference is used as a recording section for pilot signals and other sub-information signals, high-density recording can be achieved. It is possible to reproduce high-quality images at the same time.

FIG. 6 is a block diagram showing a third embodiment of the present invention constructed based on the above circumstances. However, first,
The same parts as in the second embodiment are given the same numbers and detailed explanations will be omitted. The subject image formed by the imaging optical system 7 is photoelectrically converted by the solid-state imaging device 8 and input to the process circuit 10, where it is converted into, for example, an NTSC signal and output. This output is supplied to a video signal processing circuit 11, where the luminance signal is FM modulated, and the color signal is low frequency converted and supplied to the first recording/reproducing head 3. In this way, the video signal is recorded on the outer track group OT1...OTn of the magnetic disk 1.

Audio signals, imaging data, and tracking signals are recorded on the inner circumferential portion of the disk 1 by a head assembly 30. The head assembly 30 is attached to the head support member 2. The configuration of the head assembly differs depending on whether tracking control is performed only during playback or during recording, but for example, when recording at a relatively coarse density with a track pitch of about 150 μm, it is necessary to perform tracking control only during playback. Bye. Therefore, in this case, for example, a configuration as shown in FIG. 7 may be considered. In other words, the head assemblies shown in Figure 7 are A and B.
It has a two-head configuration consisting of two heads. The A head records audio signals, photographic data, etc.
Track pitch TPA with recording/playback head for playback
Record with . Track width of A head is TWA
, and has the relationship TPA>TWA. The guard band width GBA to prevent crosstalk from adjacent tracks is GBA = TPA - TWA.
becomes. The center line of the guard band portion and the center line of the recording trace of the B head should match. That is, the B head is configured to record in the guard band portion between the recording traces of the A head. This B head is for recording a pilot signal for tracking. As is well known, the pilot signal is, for example, a signal with three types of frequencies ₁ , ₂ , and ₃ , f ₁ → f ₂ → f ₃ →
Each time the tracks are sequentially changed, as f ₁ →..., the tracks are switched cyclically and recorded. Although the details are omitted, as shown in Fig. 8, there are recording traces TB1, TB2, TB by the B head in the guard band parts of the recording traces TA1, TA2, TA3, TA4 by the A head.
3. TB4 is formed. Note that the recording traces of the A head and the recording traces of the B head partially overlap.

The explanation returns to FIG. 6. The audio signal recorded by the A head of the head assembly 30 is input from the microphone 31 and supplied to the audio signal processing circuit 32. The audio signal processing circuit 32 consists of a time-base compression/expansion circuit using means such as a CCD memory, a modulator, a demodulator, etc. The input audio signal is compressed in the time-base, and then subjected to frequency modulation, for example, by a modulator. Recorded on disk 1. During playback, the signal is demodulated by a demodulator, expanded on the time axis, returned to the original audio signal, and output from the speaker 33.

When recording various data at the same time, the data bits input using the input keyboard 34 or the like are encoded by the data signal generator 35, and are compressed on the time axis within, for example, one frame period or one field period. It is recorded by time division multiplexing or frequency multiplexing with the audio signal.

Pilot signals for tracking are sent out from the tracking control circuit 36 and are sequentially switched and recorded as described above. Note that the pilot signal may be recorded continuously, for example.
It is also possible to record in bursts at intervals of about 2 hours.

The tracking operation during playback will be briefly explained. When reproducing a track recorded as shown in Fig. 8, the pilot signal reproduced as crosstalk to the A head is separated and extracted by BPF.
This is given to the tracking control circuit 36. For example, in FIG. 8, when the A head is scanning TA2, the crosstalk signals or pilot signals f ₂ and f ₃ from the TB2 and TB3 tracks on both sides are reproduced by the A head. Compare the magnitude of the reproduced output of the reproduced pilot signals f ₂ and f ₃ and, for example, if f ₂ > f ₃ , the head has shifted to the TB2 side.
If f ₂ < f ₃ , it is determined that the deviation is in the opposite direction to the above. Then, based on this determination result, the head actuator is moved and tracking control is performed so that f ₂ =f ₃ at all times.

Next, a case of a four-head configuration will be explained. FIG. 9 shows a fourth embodiment in which a four-head configuration is used. Disk 1 is TG from the outer circumference of the disk.
It is divided into four recording track groups: TG1, TG2, TG3, and TG4. The recording/reproducing head HD1, which is in charge of the track group TG1, is initially installed at the outermost circumferential position as shown in the figure, and is driven toward the center of the disk as the number of imaged frames increases. Similarly TG
3. Recording/playback head HD3, which is in charge of TG4 and TG2.
HD4 and HD2 are each driven in the direction of the arrow shown in the figure as the number of imaged frames increases. In the case of 4 heads, the basic operation is the same as in the case of 2 heads described above. For example, the recording/playback head HD1 records the video of the first field, then the recording heads are switched and the recording/playback head HD4 records the video of the second field, and then the recording/playback head HD3 records the video of the third field. Finally, the recording/reproducing head HD2 records the fourth field. Note that when recording one frame, HD3 and HD2, which do not record video signals, can be supplied with, for example, a band-converted and time-compressed audio signal, etc. to record a number of frames in one still image. Ten seconds of audio signals can be recorded simultaneously or during dubbing.

In the example shown in FIG. 9, the movement direction of the four heads is from the outer circumferential side to the inner circumferential side of the disk 1, but the reverse direction may be used. Further, the number of heads is not limited to the two or four illustrated, and the same concept can be applied.

Each of the embodiments described above has the following effects.

(1) Since a plurality of heads are integrally mounted on the same mounting member, the distance between the heads remains unchanged. Therefore, reproducibility and compatibility in recording and reproduction can be easily achieved. Furthermore, even if the number of heads increases, only one head actuator is required, and the size does not increase even though there are a plurality of heads.

(2) Since the plurality of heads are arranged on opposite sides of the central disk mounting axis, it is mechanically easy to mount the heads, and it is also spatially easy to arrange the head adjustment mechanism.

(3) If the diameter of the disk used is 2φ,
The total stroke of the head actuator is less than 1/2φ even in the case of two heads, and the head support member does not protrude beyond the outer periphery of the disk, making it suitable for miniaturization. In the case of four heads, the stroke of head movement is further reduced.

(4) In conventional disks, the track length differs greatly between the inner and outer peripheries, resulting in a drop in image quality on the inner periphery, but with this device, 1 frame, 2
Of one frame consisting of fields, one field uses the outer track and the other field uses the inner track to compose one frame image, so it is possible to use all the frames on the disk and average the image quality. can do.

(5) High image quality with less color crosstalk can be obtained by using the outer track for luminance signals and the inner track for color signals.

(6) A still image with audio for a long period of time can be obtained by using a pair or a plurality of tracks as an audio track.

(7) Align the head with respect to the rotation axis at the center of the disk.
Since the heads are arranged 180 degrees in opposite directions, the adhesion of the multiple heads to the disk state recording medium is improved, allowing stable recording and playback with little deviation in spacing loss.

(8) Even if there are multiple heads, the distance between the heads can be kept relatively large, eliminating the problem of inter-head crosstalk during recording.

As explained above, according to the present invention, at least two of the plurality of heads are mounted on the head support arm, which is provided so as to be able to reciprocate on a straight line that is parallel to the disk-shaped recording medium and passes through the central axis of rotation of the medium. The heads are located in radial areas on opposite sides of the rotation center axis of the recording medium, and one of the heads performs recording and reproduction on the outer circumference of the recording medium, and the other one performs recording and reproduction on the inner circumference of the recording medium. Since the head is fixed integrally for recording and playing back, it is possible to record and play back image information divided into multiple tracks without having the head perform complicated operations such as track jumps. High-quality still images can be stably obtained without problems such as crosstalk between the two, and information other than image information can also be recorded and played back simultaneously on separate tracks.
It is possible to provide an image recording and reproducing apparatus in which the performance of the entire apparatus is not limited to the recording wavelength allowed on the innermost track of the disk.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the configuration of a conventional multi-head, FIG. 2 is a schematic diagram showing the configuration of a conventional separate head, and FIGS.
Figures 3a and 3b are plan and side views showing the configuration of the head, Figure 4 is a block diagram showing the configuration of the drive control system, and Figure 5 shows the present invention applied to a separate chroma system. FIG. 6 is a block diagram showing the configuration of a drive control system in a second embodiment in which the present invention is applied; FIG. FIG. 7 is a diagram showing the configuration of a head assembly used in the third embodiment, and FIG. 8 is a schematic diagram showing a data recording track and a tracking pilot signal recording track by the head assembly.
FIG. 9 shows a fourth example of a four-head configuration device according to the present invention.
FIG. 2 is a schematic plan view of the embodiment.

Claims (1)

[Claims] 1. A disc-shaped recording medium capable of recording and reproducing image information, and a disc-shaped recording medium provided so as to be able to reciprocate on a straight line parallel to the recording surface of the recording medium and passing through the central axis of rotation of the recording medium. a plurality of recording/reproducing heads integrally fixed to the head supporting arm and provided for recording and reproducing at least image information on the recording medium; a drive control means for supplying and reading the recording medium, controlling the rotation of the recording medium, controlling the drive of the support arm, etc.; They are located in radial areas on opposite sides of the recording medium, one of which performs recording and reproduction on the outer circumference of the recording medium, and the other one that performs recording and reproduction on the inner circumference of the recording medium. Features of image recording and reproducing device. 2. Claims characterized in that the disk-shaped recording medium is capable of having its center attached to the rotational shaft of the motor, and the plurality of recording or reproducing heads are arranged on the same side of the medium as the motor. The image recording and reproducing device according to item 1. 3. The image recording and reproducing apparatus according to claim 2, wherein the movable head support arm has a hole or a notch that does not come into contact with the rotating shaft of the motor. 4. When performing frame recording, one field constituting the frame is recorded on the outer periphery of the recording medium, and the other field is recorded on the inner periphery of the disk. The image recording and reproducing device according to item 1. 5. At least one head disposed on the outer circumference records a luminance signal, and at least one head disposed on the inner circumference records a color signal. The image recording and reproducing device according to item 1. 6. The image recording and reproducing apparatus according to claim 1, wherein at least one of the plurality of recording or reproducing heads records or reproduces a band-converted audio signal. 7 Items 1, 4, 5, and 7, characterized in that at least one of the plurality of recording or reproducing heads records or reproduces a tracking signal during recording or reproduction either independently or by superimposing it on another signal. An image recording and reproducing device as described in each item. 8. A patent claim characterized in that at least one of the plurality of recording or reproducing heads records and reproduces frame information signals such as a frame number, erasability signal, reproduction order designation signal, etc. in a recorded still image signal. An image recording and reproducing device according to each of the first, fourth, fifth, and seventh items. 9. The image recording and reproducing apparatus according to claim 1, wherein the recording medium is a perpendicular magnetic recording medium, and the plurality of recording or reproducing heads are perpendicular magnetic recording heads. 10. The image recording and reproducing apparatus according to claim 1, wherein the recording medium is an optical or optical-magnetic recording medium, and the recording or reproducing head is an optical head.