JPH0224862A - Tape position control method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical tape device for optical recording/reproducing or erasing using a tape as an optical recording medium, and is particularly suitable for detecting tape deviation and for tracking servo. Concerning a tape position control method.

[Conventional technology]

At present, magnetic media are commonly used as information recording media. In a recording/reproducing apparatus using a magnetic medium tape, as shown in FIG. 6, a magnetic tape l moves at low speed while being helically wound around a cylinder 3 rotating at high speed, and a signal is transmitted by a magnetic head 16 protruding from the cylinder. There is a helical scan method that records diagonally.

On the other hand, since optical recording media record and reproduce signals using finely focused laser light, recording can be performed at higher elevations than magnetic recording, and they are used in CDs, optical discs, and the like.

A device that uses a tape as an optical recording medium to record a large amount of information such as video over a long period of time using a helical scan method can be considered.

Examples of prior art related to this type of device include Japanese Patent Application Laid-Open No. 58-6664.

In order to record, reproduce, or erase signals using an optical recording medium, it is necessary to always focus a laser beam onto the recording medium and accurately scan a target signal track. In devices that use tape as an optical recording medium, signals are recorded with high density, so if the position of the tape wrapped around the cylinder shifts in the width direction due to uneven tape running or external vibration, the focused spot may not match the target. It is conceivable that the vehicle may deviate from the signal track. For optical discs that use a disc-shaped optical recording medium, track misalignment due to eccentricity of the disc is detected optically.

A method is used in which the focused spot is mechanically made to follow the track.

[Problem to be solved by the invention]

In a device that records, plays, or erases signals using a tape as an optical recording medium, if the tape shifts in the width direction, the laser focused spot will deviate from the target signal track, making it difficult to record, play, or erase signals accurately. It will no longer be done. Therefore, as with optical discs, a method is needed to optically detect the tracks and mechanically make the focused laser spot follow the tracks.

Because the tape moves in a helical fashion around a cylinder that rotates at high speeds (for example, 1800 rps+), the relative speed of the tape to the cylinder becomes extremely high, and the tracking servo must be performed at a correspondingly high speed. Unlike optical disks, the tracks are not continuous, so the tracks at both ends of the optical tape may be completely misaligned.The tracking servo, which is fast and has a wide servo range, places a heavy burden on the servo mechanism. As a result, tracking stability also deteriorates.

The above conventional technology does not take into consideration the tracking servo method for the deviation in the width direction of the tape while the tape is running and the discontinuous tracks caused by the helical scan method, resulting in problems with the burden on the servo mechanism and the stability of tracking. was there.

An object of the present invention is to provide a method and apparatus for stably tracking while reducing the burden on the tracking servo mechanism.

[Means to solve the problem]

The above object is achieved by providing a mechanism that optically detects the movement of the tape in the width direction while it is running and controls the tape to a proper position.

[Effect]

When positioning the focused laser spot on discontinuous signal tracks on the tape of the recording medium at high speed, it is possible to optically detect the deviation of the tape in the width direction and correct the tape position in advance. The burden on the tracking servo mechanism can be reduced. As a result, tracking stability is also improved.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a perspective explanatory view of a tape position control system and apparatus showing an embodiment of the present invention. Optical tape 1 (la, l
b) is wound around a cylinder consisting of upper and lower stators 3a, 3b by guide rollers 2 (2a, 2b),
A guide provided on stator 3b? Run at the normal position using IF4. On the stator 3h above the guide band 4, there are two photodetectors 5 (5a, 5b) divided into two vertically.
) provided.

A light source 6 (
6a, 6b). As the light source, for example, a semiconductor laser or a light emitting diode whose emitted light is collimated by a collimating lens (as shown) is used.

The optical tape 1 has, for example, a circular light transmitting portion 7 (7a) at the same interval as the two photodetectors 5a, 5b.

7b) are provided, the center of which is located at the detector 5.
matches the division position of . The light transmitting portion 7 is.

For example, it can be formed by melting an opaque optical recording medium on a base film using a means such as a laser beam, or by making a hole penetrating through the base film. The size of the light transmitting portion 7 is made smaller than the beam diameter of the light source. or,
Even if the light transmitting portion 7 is continuous and band-shaped, this embodiment can be applied without losing its essence.

When the light transmitting portion 7 passes the photodetector 5, if the optical tape 1 deviates from the normal position by E, the 2
Differential signal D1-D of split photodetector 5! changes as shown by curve d in Figure 2. The differential signal d near C=0 can be directly approximated and is proportional to the positional deviation amount ε of the tape 1. This signal is sent to the drive system of the guide roller 2 to control the running position of the optical tape 1 to a normal position.

The drive system of the guide roller 2 consists of a fringe 8 (8a) having an interval greater than the width of the optical tape 1.

8b) and guide shafts 9 (9a, 9b) are joined, and piezoelectric elements 10 (10a, 1
0b). When the differential output d of the photodetector 5 is positive, the optical tape 1 is shifted upward, so by compressing the piezoelectric element 10 in the axial direction, the cylinder 8 is moved downward and the optical tape 1 is normalized. Conversely, when the value is negative, the optical tape 1 is shifted downward, so by stretching the piezoelectric element 10 in the axial direction, the cylinder 8 is moved upward and the optical tape 1 is returned to its normal position. , independently of the positional control of the optical tape 1 by the guide roller 2, by changing the angle of the tracking mirror 11 of the light emitted from the light source 6C, the focused spot narrowed down by the lens 12 is moved in the vertical direction of the track. The parts that cannot be controlled by the guide roller 2 are controlled. Note that the photodetector 5
The number of divisions and the number of objects may be two or more, and even if the positional relationship between the photodetector 5 and the light source 6 is reversed, the essence of this embodiment will not be lost.

FIG. 3 is a perspective explanatory view of a tape position control system and apparatus showing another embodiment of the present invention. Optical tape 1 is wound around cylinder 3 by guide roller 2, and stator 3b
The vehicle travels in the correct position by means of a guide band 4 provided in the vehicle. Two photodetectors 5 are provided at the boundary of the guide band 4, and each photodetector 5 is irradiated with light from a light source 6 fixed outside the cylinder 3. The center of the photodetector 5 is located at the boundary between the guide bands. As the light source, for example, a semi-four-body laser or a light emitted from a light emitting diode, which is made into parallel light using a collimating lens, is used.

When the optical tape 1 deviates from the normal position by ε, the output signal of the photodetector 5 changes directly in the vicinity of ε=O, as shown by the curve f in FIG. 4(b).

This signal has an offset fo at 1=0, but by correcting the offset in advance.

A signal f-f o is obtained as shown by the curve f' in FIG. 4(c). This f' is proportional to the positional deviation amount E of the tape 1 in the vicinity of ε=0. This signal is sent to the drive system of the guide roller 2 to control the running position of the optical tape 1 to a normal position.

The drive system of the guide roller 2 is composed of a fringe 8 having an interval equal to the width of the optical tape 1, and a piezoelectric element 10, for example, cylindrical, which connects the fringe 8 to a guide shaft 9 and expands and contracts in the axial direction. When the output signal f' of the photodetector 5 is positive, the optical tape 1 is shifted upward, so the piezoelectric cable 1
0 in the axial direction, the fringe 8 is moved downward and the optical tape 1 is returned to its normal position. Conversely, when the value is negative, the optical tape 1 is shifted downward, so by stretching the piezoelectric element 10 in the axial direction, the fringe 8 is moved upward and the optical tape 1 is returned to its normal position.

Independently of the position control of the optical tape 1 by the guide roller 2, by changing the angle of the tracking mirror 11 of the light emitted from the light source 6C, the focused spot narrowed down by the lens 12 is moved in the vertical direction of the track. The parts that cannot be controlled by the guide roller 2 are controlled. In addition,
The number of the photodetectors 5 is two or more. Further, even if the positional relationship between the photodetector 5 and the light source 6 is reversed, this embodiment does not lose its essence.

FIG. 5 is a perspective explanatory view of a tape position control system and apparatus showing still another embodiment of the present invention. The optical tape 1 is wound around a cylinder 3 by a guide roller 2, and travels at a regular position by a guide band 4 provided on a stator 3b. Two light sources are provided on the upper stator 3b of the guide band 4, and each optical axis is connected to a light source fixed to the outside of the cylinder.
It passes through the center of the split photodetector. As the light source, for example, a semiconductor laser or a light emitting diode whose output light is made into parallel light using a collimating lens is used. The optical tape 1 is provided with a plurality of, for example, circular light transmitting portions 7 at the same intervals as the two light sources 6, the center of which coincides with the optical axis of the light source 6. The light transmitting portion 7 can be formed, for example, by melting an opaque optical recording medium on the base film using means such as a laser beam, or by making a hole penetrating through the base film. Further, the size of the light transmitting portion 7 is made smaller than the beam diameter of the light source. When the light transmitting portion 7 passes through the light source 6, if the optical tape 1 deviates from the normal position by a direct amount, the differential signal D of the two-split photodetector 5
1-D x changes like the curve d in FIG. 2 above.

In the vicinity of c=0, the differential signal d is proportional to the tape positional deviation amount i. This number is sent to a drive system such as a piezoelectric element provided on the rotor 3a and the guide roller 2. The positional deviation of the optical tape 1 is calculated by the parallel movement of the tape center equidistant from both guide rollers 2 and the rotational movement around the center. Separate and control in minutes. The amount of parallel movement is controlled by the vertical movement of the rotor 3a.

A rotation axis (not shown) of the rotor 3a is formed by a piezoelectric element, and a differential signal dL from the left and right photodetectors 5a+5b,
It expands and contracts according to the sign of the average value of dR, d = (d+, + di) / 2. On the other hand, the rotational movement is controlled by left and right guide rollers 2a and 2b. The guide roller 2 is composed of a fringe 8 having an interval greater than the width of the optical tape 1 and a piezoelectric cord 10 connecting the fringe 8 and the guide shaft 9. The optical tape 1 is moved by the rotor 38 and the guide roller 2, which expands and contracts the piezoelectric cables 10a and 10b according to the positive and negative values of dd+, ddR, moves the fringes 8a and 8b up and down, and returns the optical tape 1 to its normal position. Independently from the position control of Control what you can't control. Note that the number of divisions and the number of photodetectors 5 are 2.
The above shall apply. or.

Even if the positional relationship between the photodetector 5 and the light source 6 is reversed, this embodiment does not lose its essence.

〔Effect of the invention〕

As explained above, according to the present invention, deviation in the width direction of the optical tape while it is running can be detected and controlled to the normal position by vertical movement of the guide roller, thereby reducing the burden on the tracking servo mechanism. It has a mitigating effect. As a result, the stability of the tracking servo is also improved.

[Brief explanation of the drawing]

1, 3, and 5 are perspective views of a tape position control mechanism according to an embodiment of the present invention, and FIGS. 2 and 4 show the amount of tape positional deviation ε and the positional deviation obtained from the photodetector. FIG. 6, an explanatory diagram showing the relationship between signals d and f, is a perspective view of a magnetic tape drive section of a VTR using a conventional helical scan method. la, lb... optical tape, 2a, 2b... guide roller, 3... cylinder, 3a... rotor, 3b...
- Stator, 4... Guide band, 5a, 5b... Photodetector, 6a. 6b, 6cm light source, 7a, 7b, 7c-
Pore, 8...fringe, 9a, 9b...guide shaft,
10a. 10b...Piezoelectric cord, 11...Tracking mirror 12...Lens. 13a...supply reel. 13b take-up reel. 14... Pinch roller, 15... Capsuta concave first mouth 5°, 2-division special u1 early country map

Claims (1)

[Scope of Claims] 1. In an apparatus for recording, reproducing, or erasing information on a tape of an optical recording medium using an optical head composed of a light source and a group of lenses that focus the emitted light from the light source, A tape position control system characterized by providing means for optically detecting deviation in the width direction and controlling the tape to a proper position. 2. Misalignment of the tape is detected using a plurality of light sources, a plurality of light transmitting parts provided on the tape that transmit the light from the light sources, and a plurality of photodetectors that receive the transmitted light from the light transmitting parts. Claim 1, which is characterized in that detecting
Tape position control method described in section. 3. The tape position control method according to claim 1, wherein the tape position shift is detected using the tape end. 4. The tape position control method according to claim 1, wherein the tape position control is performed by driving a tape guide section or a cylinder section. 5. The photodetector is fixed within the side surface of the cylinder, and the light source is provided outside the cylinder facing each other with a tape interposed therebetween, and its optical axis is fixed so as to pass through the photodetector. 3. The tape position control system according to claim 2, wherein the photodetector and the light source are in a positional relationship opposite to that described above. 6. The tape position control system according to claim 4, wherein two or more sets of the photodetector and the light source are provided within the range of the tape's cylinder winding angle. 7. The tape position control system according to claim 2, wherein the light source is composed of a semiconductor laser. 8. The tape position control system according to claim 2, wherein the light source is comprised of a light emitting diode.