JPS62146438A - Optical recording and reproducing optical head - Google Patents

Abstract

PURPOSE:To prevent an optical head from being positionally shifted from a case body by arranging supporting bodies for supporting a convergent lens in the case body of the optical head, fitting plate springs for interposing a lens to the supporting bodies, fitting distortion gauges to the outer periphery of the supporting bodies, and correcting the displacement of the lens supporting bodies by electromotive force generated in the distortion gauges. CONSTITUTION:The opposite lens holding bodies 2 are arranged in the optical head case body 5, focus supporting springs 4 acting in the vertical direction are fitted to the surface of the supporting bodies 2 and focus actuators 7 are fitted to the lower ends of respective supporting bodies 2. The plane springs 3, 3' rectangularly bent and erected are fitted to the surfaces of respective supporting bodies 2 and the convergent lens 1 is held and fixed between the leading end parts of respective plate springs 3, 3' and the distortion gauges 8, 8' are fitted to the outsides of respective plate springs 3, 3' so as to be differentially connected. If a bend is generated in the supporting bodies 2, a differential voltage is generated when positive and negative voltages are impressed upon the distortion gauges, so that the actuators 7 are driven by the differential voltage to return the supporting bodies to the erected state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application], L The present invention relates to an optical head for optically recording and reproducing information such as digital information for a computer or information such as audio and video on a record carrier using a light beam.

[Conventional technology]

Information can be recorded by modulating a laser beam with a signal from external information and focusing it on an optical record carrier, or it can record information by irradiating a record carrier with a focused laser beam of a certain intensity. In an optical head of an optical information recording/reproducing device such as an optical disk device, the focal position is controlled so that the focused light beam spot accurately hits the surface of the record carrier, and the focus position is controlled so that the focused light beam spot hits a predetermined track on the record carrier. It is necessary to perform tracking position control to position the light beam spot. In general, tracking position control is performed by moving the entire optical head on which the entire optical system is mounted to move the beam spot over long distances.
In addition, only the focusing lens is moved to move the light beam spot over a short distance. In order to maintain the characteristics of the optical system in good condition during either long-distance or short-distance movement, it is desirable that the position of the focusing lens does not shift relative to the optical head, that is, relative to the optical center position. When the optical head housing moves, the optical head housing moves accordingly, and when the optical head housing moves, the focusing lens follows it or moves together with the housing, so that the focusing lens and optical head housing move respectively. It is desirable to control the movement of the

[Problem that the invention seeks to solve]

In order to realize the tracking control described above, it is necessary to accurately detect the position of the focusing lens with respect to the optical head housing, but conventional optical heads do not have such a position detection means. First, the only way to detect the position is through indirect means such as detecting the current of the actuator that moves the focusing lens, and it is not possible to detect the position at high speed and with high precision. It was difficult to control each movement to keep it small.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical head capable of generating a signal indicating an accurate positional relationship of a focusing lens with respect to an optical head housing in order to eliminate the above-mentioned drawbacks.

Means for Solving Problem c] The optical head for optical recording and reproducing of the present invention is provided with a focusing lens for focusing a laser beam on the surface of an optical recording carrier, and is movable in the track control direction. first and second leaf springs arranged in parallel and facing each other, and first and second leaf springs arranged and fixed on the outer surface of each leaf spring so that the detection sensitivity direction is in the bending direction of the leaf spring, respectively. 2 strain gauges, and detects a change in the resistance value of the first and second strain gauges caused by the movement of the focusing lens in the track control force direction, thereby controlling the light in the track control direction of the focusing lens. This is characterized in that a positional error with respect to the head housing is detected.

〔Example〕

The present invention will be described in detail below with reference to the drawings.
α) and (b) are a front view and a plan view schematically showing an embodiment of an optical recording/reproducing optical head according to the present invention. In the figure, in the optical head according to the present invention, a focusing lens 1 is movably supported in a track control direction by first and second leaf springs 3, 3' attached to a lens support 2, and the lens support 2 is The optical head housing 5 is supported by a focus support spring 4 so as to be movable only in the focus direction. The focusing lens 1 is driven in the track control direction by a tracking actuator 6, and is driven in the focus control direction together with the lens support 2 by a focus actuator 7.

The positional deviation of the focusing lens 1 in the track control direction is measured by first and second strain gauges 8, 8' attached to the respective outer surfaces of the first and second leaf springs 3°3' that support the focusing lens l. Detected by

FIG. 2 is a diagram explaining the principle of detecting the position of the focusing lens 1 in the track control direction.
b) is a circuit configuration diagram using strain gauges 8 and 8';
c) is a diagram showing the detection characteristic 7 of the amount of track deviation. As shown in FIG. 2 (CL), the strain gauges 8, 8' of the first workpiece 2 are connected to the first and second leaf springs 3. It is attached to the outer surface of each of the rods and is bent and bent together with the leaf spring 3.3' during movement in the track direction, changing its electrical resistance value. Same figure (α)
In this case, the first strain gauge 8 receives a tensile force, and the second strain gauge 8' receives a compressive force, and if the strain gauges have the same characteristics, there will be a difference in their electrical resistance values. The amount and polarity of the difference component change depending on the direction of the bending child. The first and second strain gauges 8, 8' arranged in this way are differentially connected, that is, as shown in the figure (α).
, one terminal 81 is connected in series as shown in (b).
A positive voltage +V is applied to the terminal 83, and a negative voltage -■ is applied to the other terminal 83. As a result, each strain gauge 8, 8'
The difference component appears at the output terminal 82 as an output voltage Vs in accordance with the electrical resistance of the voltage Vs. Therefore, the output voltage Vs changes depending on the amount of bending of the leaf spring 3.3', that is, the amount of positional deviation of the focusing lens 1 in the track control direction, and the characteristics shown in FIG. 2(c) are obtained. At this time, each optical head component is arranged so that the output voltage Vs becomes approximately O volts when the focusing lens 1 is at the optical center position of the original head. As described above, the positional relationship of the focusing lens 1 in the track control direction with respect to the optical head housing 5 can be accurately detected.

Note that the characteristic arrangement and configuration of optical elements that are one component of the optical head, such as a laser diode, a photodetector, and an optical prism, are the same as those in the prior art, so a description thereof will be omitted.

〔Effect of the invention〕

As explained above, according to the optical recording/reproducing optical head of the present invention, the positional relationship between the focusing lens and the optical head housing can be accurately detected, and this positional deviation signal can be used to move the optical head housing. This makes it possible to suppress the displacement of the focusing lens with respect to the optical head housing. Also, optical head e
By feeding back the positional shift signal to the lens actuator when moving the body, the focusing lens can be moved to follow the optical bed housing, and the focusing lens can be fixed to the optical head housing in an equally frugal manner. It is effective.

[Brief explanation of drawings]

FIG. 1(a) is a front view schematically showing an embodiment of the optical recording/reproducing optical head according to the present invention, FIG. 1(b) is a plan view,
Figure 2 shows position detection of the trunk control force direction of the focusing lens.
! FIG. 11A is a diagram illustrating the A-mounting, in which (a) is a layout diagram, (b) is a circuit configuration diagram using a strain gauge, and (c) is a diagram showing the detection characteristics of the amount of trunk displacement. l...Focusing lens, 2...Lens support, 3.3'.
...Plate spring, 4...Focus support spring, 5...Optical head housing, (5...Tracking actuator, 7
・・・Focus actuator, 8.8'...Strain gauge patent applicant NEC Corporation Representative Patent attorney Kanno Naka・,″Sa゛・,], TS\-(Ko(α)) Figure 1(b) ) Atsushi 1

Claims (1)

[Claims] (1) An optical head for optically recording and reproducing information on an optical information recording carrier supports a focusing lens for focusing a laser beam on the surface of the optical recording carrier and is movable in the track control direction. first and second leaf springs arranged in parallel and facing each other, and first and second leaf springs arranged and fixed on the outer surface of each leaf spring so that the detection sensitivity direction is in the bending direction of the leaf spring, respectively. track control of the focusing lens by detecting changes in resistance values of the first and second strain gauges caused by movement of the focusing lens in the track control direction. 1. An optical head for optical recording and reproducing, characterized in that a positional error with respect to an optical head housing in a direction is detected.