JPS62146442A - Optical information reproducing device - Google Patents

Abstract

PURPOSE:To detect the variation of an information recording carrier from a reference position only by one light beam by relatively inclining the optical axes of an illuminating optical system and a detecting optical system from an information recording medium, and arranging a part of a constitutional member of each system in an optical path. CONSTITUTION:A light beam 6 radiated from a uniformly long light source 4 is converged upon a reading area 3 on a card 1 and the image of the light is formed on an one-dimensional sensor array 9 through an image forming optical system 8. A light beam radiated from a spot light source 5 close to the light source 4 is irradiated upon a prescribed area of the card 1 through an optical system 6 and the image of the reflected light is formed on photodetecting sensors 101, 102 through an image forming optical system 8. A focus error can be detected from an output difference between the outputs of the sensors 101, 102. Thus, the focus error can be detected by the simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information reproducing device that optically reads information from an information recording carrier, and relates to an optical information reproducing device that optically reads information from an information recording carrier.

The present invention relates to an optical information reproducing device that reads signals υ from a plurality of information bits using a dimensional sensor array or a two-dimensional sensor array.

[Conventional technology]

Conventionally, devices that read information recorded on an information recording carrier and reproduce signals include facsimile machines that use one-dimensional sensor arrays, some digital copier readers, etc., and devices that use two-dimensional sensor arrays. One example is an image input device for an electronic image file device. In these information detection devices, since the input is information on paper, the size of the minimum pixel to be detected is approximately 60 μm at most, and it is difficult to use it in practice simply by mechanically determining the position of the input image. It becomes possible to configure a device without a branch.

However, as the recording density on the information recording carrier increases, for example, when a size of about 5 μm x 7 μm becomes equivalent to 1 bit, the required focus adjustment accuracy is about ±30 μm, and the signal cannot be processed without using autofocus technology. Reading becomes difficult to achieve.

Furthermore, if an optical card is constructed using an information recording density in which the size of information recording bits is approximately 5 μm x 7 μm, it is possible to provide an information medium that is highly portable and capable of handling a large amount of information.

Figure 7 shows JP-A-55-153133 and JP-A-55
This is an example of the above-mentioned information medium disclosed in No. 153139, in which signals from a plurality of dot sequences (bands) on an information recording carrier are read out in parallel, and autofocus is possible. It is a figure for explaining the principle carried out.

In the figure, 100 is a high-power laser, 101 is a diffraction grating, 102 is a deflection beam sinter, and 1103 is a λ/
4 plates, 104 is a galvanometer mirror, 1105 is an actuator, 106 is an objective lens, 107 is a record carrier, 108
109 is a sensor lens, 110 is a photodetector array, and 111 is an information signal generating optical system.

The automatic operation of the apparatus shown in FIG. 7 is carried out as follows.

A light beam emitted from a high-output laser 100 is split by a diffraction grating 101 into a plurality of light beams whose traveling directions differ by a small angle from each other.
After being transmitted through the λ/4 plate 103 and reflected by the lupano mirror 104, it enters the objective lens 106 attached to the actuator 105. A plurality of spots 108 focused on the record carrier 107 by the objective lens 106
The light flux from the sensor lens 10 travels backward along the same optical path.
9 onto a photodetector array 110 to obtain an autofocus signal.

FIG. 8 is a diagram showing a spot arrangement on the photodetector array 110. In the figure, 32b and 32b2 are focus error detection light spots, 32&11..., 3
The second beam is a light spot from the information on the record carrier 107, 44
b and 44b2 are optical sensors for detecting focus errors, and 44 & 1 +...+ 44 a n are optical sensors for detecting recording medium information.

The light spots 32b and 32b2 become farther away or closer to the center point 32a, +..., 32an when the record carrier 107 moves away from the specified position υ or approaches it. . As a result, the optical sensor 44b
Alternatively, the difference in output between the two photodetectors constituting 44b2 changes, and focus error detection is performed.

[Problem that the invention seeks to solve]

However, when attempting to use the prior art as described above for reading signals from an information carrier such as an optical card, several problems arise.

The first problem is that the amount of movement of the spot with respect to a change in the distance between the objective lens 106 and the record carrier 107 is small, and the sensitivity of focus error detection is low. In the conventional example above,
The light beam from the objective lens 106 is directed almost perpendicularly to the record carrier 10.
7), the light spora separated using the diffraction grating 101) 32b.

It is difficult to set the luminous flux constituting 32b2 at an angle that is significantly inclined from normal incidence.

The second problem is that in order to create such divided light spots, a diffraction grating 101 with a complicated shape is required, and as shown in FIG.
In addition, there are other problems in that a separate optical system for detecting focus errors (laser 1009, diffraction grating 101, deflection beam splitter 102, etc.) is required, which increases the size of the device and increases cost.

[Means for solving problems]

In view of the problems of the prior art as described above, it is an object of the present invention to provide optical information that allows focus error detection with a simpler structure that allows the general optical system that has been used in the past to be used as is. The purpose is to provide a playback device.

The above purpose is to first illuminate the information recording carrier with light.
and a second optical system that detects light emitted from the record carrier that is illuminated by the first optical system and that is modulated according to recorded information are tilted relative to the information record carrier. At least a part of each of the optical members constituting the first optical system and the second optical system is disposed in the optical path, and the distance from the reference position of the information recording carrier is υ by an optical information reproducing device characterized in that it has an optical means for illuminating an information recording carrier with at least one light beam and detecting the light emitted from the information recording carrier in order to detect fluctuations.
achieved.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described based on the drawings.

FIG. 1 is a schematic configuration diagram showing an example of an optical information reproducing device according to the present invention.

In the figure, 1 is an optical card, 2 is a recorded information string provided on the optical card 1 (hereinafter referred to as punt 0), 3 is a reading area, 4 is an LED, etc. having uniformly long dimensions. 5 is a point light source, 6 is a light source and a light car P
7 is an area on the optical card 1 that is irradiated with light from the point light source 5; 8 is an imaging optical system; 9 is a photodetector for information detection (one-dimensional sensor play); Focus error photodetector, 10. , IL2 are light receiving sensors, 12
13 is an optical head that can be driven in directions B and C in the figure, 13 is a stage on which the optical card 1 is placed and driven in direction A in the figure, and 1 and 4 are rotating rollers.

On the optical card 1, one or several bands 2 are formed of bit strings in which information is recorded. The light beam from the light source 4 is transmitted to the reading area 3 by the irradiation optical system 6.
The light is focused on. Here, in order to efficiently irradiate the reading area 3 with the light beam so as to read it as a high-quality signal, the image of the light source 4 may be made to be out of focus by an appropriate amount. However, it goes without saying that the optical arrangement must be determined so that the image of the information plane to be formed on the one-dimensional sensor array 9 via the imaging optical system 8 can be obtained with sufficient sensitivity from the sensor. In addition, the irradiation optical system 6 may be a combination of a cylindrical lens and another lens, or a rotationally asymmetric aspheric surface such as a part of a spheroid to change the cross-sectional shape + energy of the irradiation light beam. Information reading area 3 The light beam that is reflected and optically contains information is passed through an imaging optical system 8 to a one-dimensional sensor array 9.
imaged on top. The level of the signal output obtained by the one-dimensional sensor array 9 increases or decreases with respect to the "0" or 1# information on the optical card L, so this is binarized using an appropriate threshold value and converted into a digital signal. can be obtained.

Now, when a point light source 5 is placed near the light source 4, the light beam from this point light source 5 is irradiated onto a predetermined area 7 on the optical card 1 by the irradiation optical system 6, and the reflected light beam is sent to the imaging optical system. Series 8
The focus error photodetector 10's light receiving sensor to, ,
io, and a focus error signal can be obtained by a focus error detector 10. That is, the light receiving sensor 10-1
．． 10. By taking the output difference from the focus error detection power r, it becomes possible! , the principle is shown in Figures 2 and 3.
This will be explained using figures.

FIG. 2 is a diagram showing how to detect whether the optical card 1 is higher or lower than the focal position, and FIG.
is higher than the reference position, Figure 2 (b) shows optical card 1.
is at the reference position, and FIG. 2(c) shows the case where the optical card 1 is at a lower position than the reference position.

Figure 3 shows 2 in each case of (a), (b), and (c).
Light receiving sensors 10, 1 on the split focus error photodetector 10
2 is a diagram showing the position of a light spot generated on 0-2. FIG.

In the present invention, since the illumination light beam is incident on the optical card 1, when the optical card 1 moves in the vertical direction as shown in FIG. 2, a vertical movement of the spot occurs on the photodetector surface.

Each light receiving sensor 10 caused by this movement. ,10-2
A focus signal can be obtained by taking the differential between the two.

For example, as shown in FIG. 2 (&), when the optical card 1 is at a higher position than the reference position, a light spot is formed at the position (&) in FIG. 3, and only the light receiving sensor 10-4 is output, and the position of the optical card 1 can be detected.

On the other hand, when the optical card is located at a lower position (than the reference position) as shown in FIG. 2(c), only the light receiving sensor 10-1 outputs an output, which can be detected in the same manner.

Further, when the optical card 1 is at the reference position as shown in FIG. 2(b), a light spot is formed at the position shown in FIG. ．． The angle of 10° divides the light spot into two parts, which can be detected from their outputs.

FIG. 4 is a schematic side view showing a second embodiment of the present invention.

In the figure, 50 is an auxiliary optical system, 51 is a slit-shaped mask, 52 is a roller, and 53 is an actuator 154.
, 54' are focus error photodetectors, respectively. In this embodiment, the same members as in the first embodiment shown in FIG. 1 are given the same numbers.

In this embodiment, a slit-shaped mask 51 is arranged at a position in image formation relationship with the reading area 3, and this mask 51 is illuminated with light from the light source 4 by an auxiliary optical system 50. This auxiliary optical system 50 may include a cylindrical lens or a lens lens, if necessary.

A mirror lens, a diffuser plate, etc. can be used. mask 5
The aperture 1 is imaged onto the optical card 1, and is imaged by the imaging optical system 8 onto a surface including a photodetector 9 for information detection. Focus error photodetectors 54 and 54' are arranged on both sides of the one-dimensional sensor array 9, and an image of the edge of the mask 51 is formed in each photodetection area. That is, the auxiliary optical system 50 and the mask 51 are used as means for generating focus error detection light, similar to the point light source 5 of the embodiment described above.

When the optical card 1 moves up or down from the standard focusing position, the formed helical image moves up or down, and as a result, the photodetector 5
The output from 4.54' is unbalanced and focus error detection is performed. Focus error correction is performed using a roller 5 placed directly below the reading area 3 of the optical card 1.
2 up and down using an actuator 53, and by moving the entire optical system or a part of the optical system by an actuator (not shown), and good information reading is always performed.

FIG. 5 is an enlarged view showing the arrangement of the one-dimensional sensor array 9 and the focus error photodetector used in a modified example of the second embodiment of the present invention.

In the figure, a one-dimensional sensor array 9 includes a photodetector section 9.
and charge transfer sections 9□, 93. Focus error photodetectors 55, 55' detect focal errors at one end of the reading area, and photodetectors 56, 56' detect focal errors at the other end of the reading area. . The advantage of this configuration is that even if the optical card has a large curve υ, it is possible to perform good signal detection over the entire reading area by simply using one set of actuators that move the card in the vertical direction. Become.

FIG. 6 shows the desired mask 5 when implementing the second embodiment.
1 and 1-dimensional sensor array 9, focus error photodetector 5
4.54' is a schematic side view showing the arrangement.

In the figure, the same members as in the second embodiment are given the same numbers. Each optical element is arranged on a surface conjugate to the surface of the optical card 1. If 60 and 61 are the main planes on the object side and image side of the imaging optical system 8, respectively, then the conjugate plane with respect to the information plane of the card 1 is the plane 62, which is known as the "Scheimpflug condition", and this plane 62 By arranging the photodetectors 54° and 54' inside the lens, it is possible to detect focus errors with good accuracy.

The present invention is not limited to the embodiments described above, and various modifications are possible.

For example, in the embodiment described above, the information detection photodetector 9
Although we have taken an example using a one-dimensional sensor array, it is also possible to use a two-dimensional sensor array without any modification. It is also possible to use a part of the two-dimensional sensor as a focus error detector.

Further, in the above embodiments, the case where the information recording carrier is a reflective type is explained, but it is clear that a transmissive type information recording carrier can also be used.

In the case of a transmission type, it is preferable for the optical axes of the irradiation optical system and the imaging optical system to be tilted relative to the information recording carrier for rounding to improve the accuracy of focus error detection.

Note that the focus error detector that can be used in the present invention is not limited to the two-split sensor as in the above embodiment, but also a binfet diode array arranged in the direction in which the focus error detection circular light flux (spot light) is shifted, or in the same direction. There are various kinds of one-dimensional sensor arrays having a longitudinal direction.

〔Effect of the invention〕

As described above, according to the optical information reproducing device of the present invention, it is possible to provide an optical information reproducing device capable of detecting focus errors with a simpler structure than conventional devices.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an optical information reproducing apparatus of the present invention, and FIGS. 2 and 3 are diagrams for explaining a method for detecting a focus error, respectively. FIG. 4 is a schematic configuration diagram showing a second embodiment of the present invention, FIG. 5 is an enlarged view showing an example of the arrangement of photodetectors, and FIG. 6 is a diagram of a desirable optical system when implementing the second embodiment. This is a schematic (11!) view showing the arrangement. FIGS. 7 and 8 are a schematic configuration diagram of a conventional optical information reproducing device and an enlarged view of its photodetector portion, respectively.

Claims (1)

[Claims] (1) A first optical system that illuminates an information record carrier with light; and a second optical system that detects light emitted from the record carrier that is illuminated by the first optical system and modulated according to recorded information. each have an optical axis tilted relative to the information recording carrier, and at least a part of each optical member constituting the first optical system and the second optical system is disposed in the optical path. optical information, characterized in that it has an optical means for illuminating the information recording carrier with at least one beam of light and detecting light emitted from the information recording carrier in order to detect a variation of the information recording carrier from a reference position. playback device.