JPS5939828B2 - Regeneration needle drive device for information signal regeneration element - Google Patents

Description

[Detailed Description of the Invention] In recent years, high-density recording and reproduction of various information signals have been performed using information recording media disks (hereinafter sometimes abbreviated as disks).
It is well known that research and development efforts have been actively conducted to improve the recording and reproduction of information signals using disks, and many proposals have been made to date regarding high-density recording and reproduction of information signals using disks. The company has also been conducting research into high-density recording and reproducing methods for information signals using various types of discs.

As a result of considering the results of previous research, the applicant company found that the disc must be of a grooveless format so that the playback mode can be changed freely during playback, and that the information signal from the disc must be a grooveless type. reading (detection)
Considering the fact that the capacitance change detection method is the best method and other conditions, we developed a high-density recording and reproducing method for information signals using non-groove disks (hereinafter referred to as non-groove disks). We have been promoting practical research on the
(Refer to Publication No. 5), the original form was proposed.

In one embodiment of the information signal recording and reproducing method already proposed by the applicant company mentioned above, pits corresponding to the main information signals are arranged in a spiral or concentric pattern on a flat surface. , so that spiral or concentric recording marks (tracks) are spaced apart by a predetermined interval (track pitch) on a flat surface, and by an arrangement of pits corresponding to the above-mentioned main information signals. A region (space) in which there is no pit corresponding to the main information signal is formed between adjacent tracks (hereinafter sometimes abbreviated as main information signal tracks) formed by the main information signal. In addition, pits corresponding to tracking control signals are intermittently arranged in the spiral or concentric space formed between adjacent tracks in each phase, and the tracking control signal described above is carried out in the space. A spiral or concentric track (hereinafter sometimes abbreviated as a tracking control signal track) is formed by an arrangement of pits corresponding to the main information signals, and a tracking The control signal and the corresponding pit exhibit a recording pattern in which they overlap each other to some extent in the width direction of the pit, and have different frequency values as the tracking control signal. using two signals, and switching the two signals alternately every rotation of the disk,
One of the two signals constitutes a disk in which a track is intermittently formed in the space by an array of pits corresponding to the other information signal, and the main information from the disk is Signal reproduction is performed using an electrode width (reproduction) that is approximately the same as the pit width of the pit corresponding to the main information signal in the disk (same as the track width of the track formed by the pit corresponding to the main information signal). A reproduction stylus (scanning stylus) is equipped with an electrode having a width (width) and is capable of contacting the surface of the disc with a contact width wider than the track pitch in the width direction of the track. The information signals are detected by detecting changes in capacitance between each information signal formed on the electrode and disk and the corresponding pit. The signal obtained from the tracking control signal track formed in the space on both sides of the information signal track is used as the tracking control signal, and the center of the electrode in the regeneration needle and the main information signal are controlled by the operation of the tracking servo system. An arrangement is shown in which the center of the track is always aligned.

When reproducing information signals from the above-mentioned grooveless disc, tracking is performed by the operation of a tracking servo system so that the reproduction needle always accurately tracks the recording trace to be reproduced. Needless to say, the regenerating needle is required to be controlled, and the regenerating needle is driven and displaced by a tracking control drive device in a tracking servo system.

Furthermore, although disks are designed to be rotated accurately at a predetermined number of rotations when reproducing information signals, disks are inevitably subject to mechanical deformation due to various other causes during manufacturing. Even if it is rotated at a constant number of rotations during playback, the relative speed between the recording trace and the playback needle will change due to the presence of the mechanical deformation described above. This causes a so-called time axis error (jitter) to be included in the reproduced signal.

For this reason, conventionally, a time axis error correction signal obtained by comparing a reference signal in the reproduction signal with a standard signal is applied to the drive device of the time axis error correction control circuit of the reproduction needle, thereby causing the reproduction needle to move. The driving displacement is performed in the direction in which the recording trace extends, so that no time axis error occurs in the reproduced signal.

Therefore, when reproducing information signals from a grooveless disc, there are two types of control: time axis error correction control and tracking control.
It is necessary to drive and displace the reproducing needle two-dimensionally in both the extending direction of the recorded trace and the direction orthogonal thereto by one control.

Therefore, the applicant company has previously proposed a regeneration stylus drive device that can drive and displace the regeneration stylus two-dimensionally when reproducing a grooveless disc. 1 to 3 are plan views showing a schematic configuration of a regenerated needle 1 drive device for explaining the configuration principle and operating principle of the regenerated needle drive device already proposed by the above-mentioned applicant company. In FIGS. 1 to 3, 1 is a regenerating needle, 2 is a movable member including a cantilever, and this movable member 2 is supported by an elastic support 3 such as a rubber membrane, so that A regenerating needle 1 fixed to the tip thereof is made to be freely displaceable while being pressed against the surface of the grooveless disc with a required needle pressure.

The ends of the movable member 2 mentioned above are marked with N in the figure.
A permanent magnet 4 magnetized like S is fixed.

The movable member 2 is composed of two parts: a cantilever to which the regeneration needle is fixed, and a part to which the permanent magnet 4 is fixed, and these two parts are connected by magnetic coupling means (
It is a desirable mode of implementation that the components are integrally connected using a magnetic coupling (this point also applies to the implementation of the present invention, which will be described later). The above-mentioned permanent magnet 4 is attached to excitation coils A, B (in the case of FIGS. 1 and 2) and excitation coils Al, A2, Bl, B2 (in the case of FIG. 3) attached to the magnetic path forming member 5. The excitation coil A is placed in the magnetic field generated by the
, B, Al, A2, Bl, B2, etc., the permanent magnet 4 is driven and displaced horizontally or vertically in the figure, thereby fixing it to the movable member 2. The reproduced needle is driven and displaced on the surface of the grooveless disc in the direction in which the recorded trace extends or in the direction perpendicular thereto.

To explain the above point in detail with reference to Figs. 1 and 2, in Figs. is caused to flow, the electromagnetic force generated between the current flowing through each excitation coil A, B and the permanent magnet 4 causes the regeneration needle 1 to move in the direction of the arrow in the figure in the case shown in the first diagram. In the case shown in the second figure, the regenerating needle 1 is displaced in the Y direction as shown in the figure.
This displacement in the direction is clear from the so-called Fleming's left hand finger rule.

In this way, when the direction of the current flowing through the excitation coils A and B is determined, the direction in which the regeneration needle 1 is driven and displaced is displaced in the X direction and the Y direction accordingly, and The magnitude of the displacement of the needle 1 corresponds to the magnitude of the current flowing through each exciting coil A, B. In addition, in FIGS. 1 and 2, if the direction of the current flowing through each exciting coil A and B is reversed from the illustrated state, the regeneration needle 1 will be driven and displaced in the opposite direction to the arrow in the figure. It is clear that Now, the connection polarity of the excitation coils A and B when a current is applied to the excitation coils A and B in the direction shown in Fig. 1 is defined as the positive connection polarity. On the other hand, if the connection polarity of excitation coils A and B is set to be opposite connection polarity when the current flows in the direction shown in Figure 2, excitation coils A and B will be connected with positive connection polarity. When current is applied to the excitation coils A and B in this state, the regeneration needle 1 is as follows.
Excitation coil A is driven and displaced in the recording trace extension direction X, and excitation coil A and B are connected with opposite connection polarities.
, B, the playback needle moves in the direction of extension of the recorded trace
It can be said that the drive displacement is carried out in the direction Y perpendicular to the direction Y.

Therefore, by determining the direction and magnitude of the current flowing through the excitation coils A and B, the regeneration needle 1 can be driven and displaced two-dimensionally.

Figure 3 shows two sets of excitation coils A and B, respectively.
1, A2, Bl, B2, and the coil A
1 and B1 are connected with positive connection polarity, and coil A1
and B2 are connected with opposite connection polarity, and in the structure shown in the third figure, the regeneration needle 1 is displaced by one drive in the X direction by the current flowing through the coil A1 and the coil B1, Further, the regeneration needle 1 is driven and displaced in the Y direction by the current flowing through the coil A2 and the coil B2.

The previously proposed regenerating needle drive device described above is capable of driving and displacing the regenerating needle two-dimensionally in accordance with the above-described principles of construction and operation. The drive device is constructed by attaching a permanent magnet 4 to a movable member 2 including a cantilever to which a regeneration needle is fixed. Since the movable member 2 is driven by an electromagnetic force, the magnitude of the driving force for driving the movable member 2 is determined when the magnitude of the current flowing through the excitation coils A and B is constant. In this case, the larger the magnetic force of the permanent magnet 4 is, the larger the magnetic force becomes.

On the other hand, in order for tracking control and time axis error correction control to be performed well on the regeneration needle 1, the servo system for performing each of the above-mentioned controls must have good tracking characteristics. Therefore, the drive system of the part that drives the regeneration needle 1 must exhibit a high resonant frequency. The magnet 4 must also be extremely small and lightweight.

However, as is well known, the magnetic force of a permanent magnet changes depending on its shape and size, and a permanent magnet that is extremely small and lightweight as described above cannot generate a large magnetic force. Therefore, in the previously proposed regeneration needle drive device, it is difficult to drive the movable member 2 with a large driving force, and as a result, there is a risk that the desired control may not be performed at times. This became a problem. The present invention drives and displaces a playback needle that reads information signals from a recording trace on an information recording medium disc in the direction of extension of the recording trace in accordance with a time axis error correction signal, and also drives and displaces a reproduction needle that reads an information signal from a recording trace on an information recording medium disc in a recording trace extension direction in accordance with a correction signal for tracking control. A movable member supported by a support so as to be freely displaceable integrally with the reproducing needle, as a reproducing needle driving device for an information signal reproducing element configured to displace the information signal reproducing element by one drive in a direction perpendicular to the direction in which the trace extends. and a coil poppin in which two coils each wound in a planar shape are fixed to the circumferential surface in a substantially symmetrical arrangement, and one end is fixed to the support described above; a DC magnetic field forming member in which pairs of magnetic poles of different polarities are arranged opposite each other to form a magnetic field into which only one side portion of each coil is inserted; There is provided a reproducing needle drive device for an information signal reproducing element, which comprises means for separating each other side portion of the coil from the magnetic field of the above-mentioned DC magnetic field generator, and the above-mentioned previously proposed device is improved. This device solves the above-mentioned problems in the regeneration needle drive device, and its contents will be explained in detail below with reference to the attached drawings.

FIG. 4 is a perspective view of one embodiment of the reproducing needle driving device for the information signal reproducing element of the present invention, in which 1 is a reproducing needle, 2 is a movable member including a cantilever, and In this illustrated example, the movable member 2 is shown as a cantilever.

Reference numeral 3 denotes an elastic support such as a rubber film, and this elastic support 3 is stretched over mounting bodies 7 and 8 implanted in the substrate 6, and supports the cantilever 12 described above. There is. A regeneration needle 1 is fixed to one end of the cantilever 12, and a movable coil MC is integrally fixed to the other end of the cantilever 12. The above-mentioned moving coil MC is constructed by fixing the coils 12 and 13 wound in a planar manner to the circumferential surface of the coil bobbin 11.
is fixed at one end to the elastic support 3 described above.

As can be seen from the cross-sectional shape shown in the plan cross-sectional view of FIG. 6, the end of the coil bobbin 11 that is fixed to the elastic support 3 has a truncated conical shape.

Reference numeral 9 denotes a leader line for the information signal read by the electrode section of the reproduction needle 1, and this leader line 9 is connected to a terminal 10 provided on the substrate 6.

An elastic material such as a phosphor bronze wire is used as the above-mentioned leader line 9, and this leader line 9 has both the function of extracting information signals and the function of pressing the playback stylus 1 against the surface of the disc with an appropriate stylus pressure. It is one of the desirable embodiments to configure it so that it can be moved. Both ends of the coil 12 in the movable coil MC described above are connected to terminals 15 and 16 provided on the board 6, and both ends of the coil 13 in the movable coil MC are connected to terminals 17 and 18 provided on the board 6. There is.

Reference numeral 20 denotes a DC magnetic field forming member, and this DC magnetic field forming member 20 is used in combination with the above-mentioned moving coil MC. The moving coil MC is a DC magnetic field forming member 20
When used in combination with the moving coil MC
One side portion 12a of each coil 12, 13 in
, 13a are placed in a magnetic field formed between each pair of magnetic poles of different polarity.
b.

Further, the above-mentioned moving coil MC is a member 2 for forming a DC magnetic field.
0, the other side portions 12b and 13b of each of the planarly wound coils 12 and 13 fixed to the circumferential surface of the coil bobbin 11 in the movable coil MC are as follows. , is located at a location separated from the magnetic field in the DC magnetic field forming member 20 described above.

The DC magnetic field forming member 20 described above may be a permanent magnet having a desired shape, or may be formed by excitation coils 19a, 19 having cores having a desired shape as shown by imaginary lines 19a, 19b in FIG.
It may be an electromagnet excited by b, but from the viewpoint of simplifying the structure, it is better to use a permanent magnet.

The specific structure of the DC magnetic field forming member 20 described above will become clearer with reference to the cross-sectional views shown in FIGS. 6A and 6B. In the description of the following embodiments, the DC magnetic field forming member 20 will be described as being made of a permanent magnet, and the DC magnetic field forming member 20 may also be referred to as a permanent magnet 20.

In FIG. 4, the permanent magnet 20 has a magnetic pole forming portion 20a facing one side portion 12a of the coil 12 of the movable coil MC, a magnetic pole forming portion 20b facing the one side portion 13a of the coil 13, and a center A magnetic pole forming portion 20c is provided.

The gaps 14a and 14b are formed between the central magnetic pole forming portion 20c and the magnetic pole forming portions 20a and 20b. Since the moving coil MC is inserted through the tip of the central magnetic pole forming portion 20c, one side portion 12a of the coil 12 of the moving coil MC is connected to the magnetic pole forming portion 20a of the permanent magnet 20 described above. The one side portion 13a of the coil 13 of the movable coil MC is placed in the strong magnetic field of the air gap 14a formed between the tip of the forming portion 20c of the permanent magnet 20 and 2
0b and the tip of the central magnetic pole forming portion 20c, the other side portions 13b and 14b of the coil 12 and the coil 13 of the movable coil MC are , as mentioned above, the gap 14a, 14b formed between the center magnetic pole forming portion 20c of the permanent magnet 20 and the magnetic pole forming portions 20b, 20c of the permanent magnet 20, separated from the magnetic field. (a position with no magnetic field or a position with an extremely weak magnetic field).

That is, since the other side portions 12b and 13b of each of the coils 12 and 13 in the above-mentioned movable coil MC are placed in a portion where no magnetic field is formed, the respective coils 12 and 1 of the above-mentioned movable coil MC
The magnetic flux does not interlink with the other side portions 12b and 13b of 3.
The coil 1 of the movable coil MC is connected via the terminals 15 and 16 to the regenerating needle drive device shown in FIG.
2 and also to the coil 13 of the movable coil MC via the terminals 17 and 18, depending on the polarity and magnitude of the current supplied to the coils 12 and 13 of the movable coil MC. The playback needle 1 can be driven and displaced by a required amount in the direction of extension of the recorded trace or in the direction perpendicular to the direction of extension of the recorded trace.

Fig. 5 shows the state shown in Fig. 4 above, with the permanent magnet 20 removed, and when replacing the regeneration needle, etc., all the parts assembled as shown in Fig. 5 are put together. It is recommended that it be replaced by

FIGS. 8a and 8b show the principle of construction and operation of the reproduction needle drive device shown in FIG. 4, which has already been described as an embodiment of the reproduction needle drive device of the information signal reproduction element of the present invention. FIG. 2 is a plan view illustrated so that the principle can be clearly understood.

In FIGS. 6A and 6B, when currents in the directions shown are applied to the respective coils 12 and 13 in the movable coil MC, the regeneration needle 1 in the case shown in FIG. The playback needle 1 is driven and displaced in the direction of arrow It is driven and displaced in the orthogonal direction. As is clear from FIGS. 6A and 6B, the regeneration needle drive device having the configuration shown in FIG. If a current is applied in the direction shown, the regeneration needle 1 will move in the direction of X and Y in each figure.
The coils 12 and 13 in the movable coil MC are driven and displaced in the direction of the arrow in FIGS. 6A and 6, respectively.
When a current in the direction opposite to that shown in figure b is applied, the regeneration needle 1 is driven and displaced in the direction opposite to the direction of the X and Y arrows in each figure. It turns out.

Therefore, a time axis error correction signal is passed as a current in the direction as shown in FIG. 6a to the coils 12 and 13 of the movable coil MC in the regenerative needle drive device configured as shown in FIG. In addition, the coils 12 and 13 of the movable coil MC
On the other hand, if a correction signal for tracking control is passed as a current in the direction as shown in FIG. 6b, the regeneration needle drive device having the configuration shown in FIG. Correction of time axis errors and tracking control can be performed simultaneously.

FIG. 7 shows how the correction signal Ey for tracking control generated in the tracking servo system and the time axis error correction signal Ex generated in the time axis error correction circuit are processed and sent to the moving coil MC. FIG. 7 shows an example of the configuration of the arithmetic circuit 22 which generates a signal to enable the reproduction needle driving device to simultaneously perform tracking control operation and time axis error correction operation. 22a and 22b are level setters, 22c is an adder, 22d is a subtracter, 22e and 22f are drive amplifiers, 2
2g and 22h are output terminals.

The arithmetic operation in the arithmetic circuit 22 is performed by determining that the direction of the current flowing through the coils 12 and 13 of the movable coil MC is positive when the direction is as shown in FIG.
The following equations (1) and (2) are obtained when the currents flowing in the terminals 2 and 13 are respectively 11 and 12, and the amount of displacement in the X direction is X, and the amount of displacement in the Y direction is Y. (
However, Kx and Ky are constants), and from the relationship between the displacements X and Y and the currents 11 and 12, the currents shown in equations (3) and (4) above are generated. The output signal is sent from the terminals 22g and 22h to the coils 12 and 13 of the movable coil MC.
In addition, the reproduction needle drive device can perform a tracking control operation and a time axis error correction operation two-dimensionally at the same time.

As is clear from the detailed explanation above,
The reproduction stylus driving device of the information signal reproduction element of the present invention drives and displaces the reproduction stylus that reads information signals from the recording trace on the information recording medium disk in the direction of extension of the recording trace according to the time axis error correction signal, and also performs tracking. As a reproducing needle drive device for an information signal reproducing element, which is configured to displace the information signal reproducing element by one drive in a direction perpendicular to the direction of extension of the recorded trace in response to a correction signal for control, it is freely displaceable integrally with the reproducing needle. As shown in FIG. A DC magnetic field formed by arranging each pair of magnetic poles of different polarity opposite each other to form a magnetic field in which the fixed coil poppin and only one side portion of each of the two coils described above are inserted. forming member, and the above-mentioned 2
A reproducing needle drive device for an information signal reproducing element is constituted by means for separating the other side portion of each coil from the magnetic field of the above-mentioned DC magnetic field generator. A strong electromagnetic force is generated between the current flowing through one side of the two coils 12 and 13 and the sufficiently strong magnetic field generated in the magnetic gap in the DC magnetic field forming member 20. By this means, the regeneration needle can be strongly driven and displaced, whereby the amount of displacement of the regeneration needle can be set to a value that can sufficiently satisfy the amount of displacement required during control operation in a control system. In addition, since the drive system including the regenerated needle 1 can be driven with a sufficiently large driving force as described above, the stiffness of the elastic support 3 that supports the movable member 2 and other Even if the stiffness of the support is increased, the regenerated needle 1
The amount of displacement can be set to a desired value, and therefore, the resonant frequency of the drive system including the regeneration needle can be increased to improve the follow-up characteristics of the servo system.

[Brief explanation of drawings]

1 to 3 are plan sectional views of main parts for explaining the construction principle and operating principle of the reproducing needle drive device of the previously proposed information signal reproducing element, respectively, and FIG. 4 is the information signal reproducing element of the present invention. A perspective view of an embodiment of the regenerating needle drive device of FIG.
The figure is a perspective view of a part of the same as above, FIGS. 6A and 6B are plan sectional views of the device for explaining the construction principle and operating principle of the reproducing needle drive device for the information signal reproducing element of the present invention, and FIG. FIG. 2 is a block diagram of an example of an arithmetic circuit. 1... Recycled needle, 2... Movable member, 3.
...Elastic support, 4...Permanent magnet, 5.
...Magnetic path forming member, 6...Substrate, 11.
...Coil bobbin, 10,15-18...
・Terminal, 12, 13... Coil, 12a, 13
a... Part on one side of the coil, 12b, 13b
・・・・・・Part on the other side of the coil, 20・・・・・・
DC magnetic field forming member, 14a, 14b... air gap, 22... arithmetic circuit, 22a, 22b...
...Level setter, 220... Adder, 22d
...Subtractor, 22e, 22f...Drive amplifier, MC...Moving coil.

Claims (1)

[Claims] 1 Drive and displace the playback needle that reads the information signal from the recorded trace on the information recording medium disk in the direction of extending the recorded trace in accordance with the correction signal for the time axis error, and extend the recorded trace in accordance with the correction signal for tracking control. A reproducing needle driving device for an information signal reproducing element configured to drive and displace the information signal reproducing element in a direction perpendicular to the reproducing needle, the movable member being supported by a support so as to be freely displaceable integrally with the reproducing needle; A coil bobbin in which two coils each wound in a planar shape are fixed to the circumferential surface in a substantially symmetrical arrangement and one end is fixed to the above-mentioned support;
a direct current magnetic field forming member in which pairs of magnetic poles of different polarities are arranged opposite each other to form a magnetic field into which only one side of each coil is inserted;
A reproducing needle drive device for an information signal reproducing element, comprising means for separating the other side portions of the two coils from the magnetic field of the DC magnetic field generator.