JPS6258426A - Detector for position being irradiated by light beam - Google Patents

Abstract

PURPOSE:To detect accurately a position being irradiated by a light beam by obtaining centers of the irradiated position of the light from a light source and that of the light beam from a pickup, and calculating the distance between these centers to calculate a light beam irradiated position relative to a light transmission control part of a disc. CONSTITUTION:A light source 15 emits a light beam B, and the light beam B is projected to a light receiving part 16 through a light-transmissive part 111. Meanwhile, a light beam A projected from a pickup 13 strikes a signal recording face of a disc 11 and is reflected partially, and a part of this light beam is projected to the light receiving part 16 through the disc 11, and photoelectrically converted parallel data is supplied to dividers 25 and 26 through a shift register 19, a leading edge detecting circuit 21, a trailing edge detecting circuit 22, and counters 23 and 24, and operated values are supplied to an adder 27 and are added. Thus, the error component due to eccentricity of the disc is not included in position data taken out from the adder 27.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an optical disc recording/reproducing device capable of recording information signals by e.g. The present invention relates to a light beam irradiation position detection device that can detect the irradiation position of a light beam.

[Technical Background of the Invention and Problems Thereof 1 Recently, various optical disc recording and reproducing systems have been developed that enable recording and reproducing information signals using light beams. One method is to form tracking guide grooves in a plurality of concentric circles or spirals on the signal recording surface of an optical disk, and direct a light beam that blinks or changes according to the information signal onto the guide groove of the disk. A signal train consisting of recording bits (holes with a depth of about 0.1 g) or chemically changed parts (portions with different reflectances due to chemical changes in the recording layer) is formed on the guide groove. Accordingly, methods for recording information signals have been considered.

By the way, when recording information signals on a disk as described above, it is necessary to detect the irradiation position of the light beam on the signal recording surface of the disk as accurately as possible in order to irradiate the light beam onto the target recording groove. . In this case, for example, CD
As seen in the (compact disc) system, in a system in which the information signal in the green area contains information indicating the position on the disc where it is recorded, the signal string is traced with a light beam and the information is transmitted. By reading the signal, the position of the light beam on the disk can be easily detected. However, in the case of a method in which information indicating the recording position is not included in the recorded information even in unrecorded areas or recorded green areas, no position information can be obtained, so it is difficult to accurately detect the irradiation position of the light beam. This is extremely difficult.

In order to solve these problems, light beam irradiation position detection devices as shown in FIGS. 5 and 6 have been proposed in the past. First, to explain the device shown in FIG. 5, a is an optical disk, b is a disk motor,
C is the pickup, d is the feed motor, and the pickup C
is movable in the radial direction of the disk a by a feed motor d. A slider e is attached to this pickup C. As the pickup C moves, the slider e slides on a resistor Q that constitutes a position detection section f and extends in the radial direction of the disk a. A voltage element E is applied to the resistor Q. Therefore, a voltage (2) corresponding to the moving position of the pickup C can be taken out from the slider e. This voltage (■) corresponds to the light beam irradiation position.

Next, the apparatus shown in FIG. 6 will be described. The same parts as in FIG. 5 are denoted by the same reference numerals, and different parts will be described here. That is, a light emitting element such as a phototransistor for position detection is attached to the pickup C, and a light receiving section 1 having a large number of light receiving elements such as photodiodes arranged in the radial direction of the disk is provided in the irradiation direction. It is being The outputs of each light receiving element of the light receiving element 8IXi are respectively led out in parallel to a signal processing circuit j. This signal processing circuit j detects from the output signal of the light receiving section 1 which position of the light receiving section i is irradiated with the light beam from the light emitting element, and the detected data is stored on the signal recording surface of the disk a. Corresponds to the light beam irradiation position.

However, in the device shown in FIG. 5, since the slider e is in contact with the resistor Q, a load is placed on the pickup feeding mechanism, making it impossible to feed the pickup at high speed. In addition, the resistor g cannot avoid aging due to wear. On the other hand, the device shown in FIG. 6 has drawbacks such as the need to newly provide a light emitting element in the pickup and the need for a driving circuit for the light emitting element.

Furthermore, the above two devices attempt to determine the position of the light beam by detecting the position of the optical pickup itself that generates the light beam and irradiates it onto the signal recording surface of the disk. However, not only does this have poor detection accuracy, but if there is a so-called eccentricity where the center of the guide groove and the center of rotation of the disk are different, the absolute position relative to the center of rotation of the disk can be detected, but the center of the guide groove Since it is not possible to detect the position relative to
For example, it is not possible to move the light beam to the intended guide groove.

[Objective of the Invention] The present invention has been made in consideration of the above-mentioned circumstances, and it is an object of the present invention to detect the irradiation position of a light beam extremely accurately without errors due to eccentricity of the guide groove of the disk or the eccentricity of the signal train. An object of the present invention is to provide a light beam irradiation position detection device that can perform the following functions.

[Summary of the Invention] That is, the light beam irradiation position detection device according to the present invention includes a tracking guide groove formed on a signal recording surface or a ring having the same center as a signal array having a different reflectance according to an information signal. a disk formed with a light transmission control section having a shape, and an information signal recorded on the disk by irradiating the guide groove with a light beam that changes according to the information signal while moving in the radial direction of the disk; a pickup that reads information signals recorded on the disk by irradiating the disk with a light beam of a predetermined wavelength while moving in the radial direction of the disk and receiving reflected light of the light beam changed by the signal train; , a light source that irradiates light near the light transmission control section on one side of the disk;
a light-receiving section including a plurality of light-receiving elements of the same size disposed at a position facing the light source on the other surface side of the disk and arranged in the movement direction of the pickup over its movement range; a beam irradiation means for irradiating a part of the light beam onto the light receiving section; and a beam irradiation means that detects the output level state of each light receiving element of the light receiving section to determine the light irradiation position from the light source and the light beam irradiation position from the pickup. The present invention is characterized by comprising position calculation means for calculating a light beam irradiation position relative to the light transmission control section of the disk by finding each center and calculating the distance between the centers.

[Embodiment of the Invention] An embodiment of the invention will be described below with reference to FIGS. 1 to 4. However, in FIGS. 1 to 4, the same parts are denoted by the same reference numerals, and only the different parts will be described here.

FIG. 1 shows its configuration, and reference numeral 11 in the figure is a disk. This disk 11 is formed of a translucent resin into a donut shape, and a tracking guide groove (not shown) is spirally formed from the inner circumference to the outer circumference on the lower surface of the disk 11 in the figure. Furthermore, a ring-shaped light transmitting portion 111 having the same center as the guide groove is formed on the inner periphery of the guide groove. This disk 11 is the disk motor 1
2 at a predetermined speed.

Further, an optical pickup 13 is provided at the bottom of the disk 11 in the figure. When recording information, this optical pickup 13 irradiates the guide groove of the disk 11 with a light beam A that blinks or changes depending on the information signal to be recorded, so that recording bits or A signal train called a chemical change part is formed. Furthermore, during information reproduction, the information signal recorded on the disc 11 is read out by irradiating the light beam A onto the signal train of the disc 11 and receiving the reflected light that has been changed by the signal train. be.

This pickup 13 is controlled by a focus servo circuit and a tracking servo circuit (not shown).

That is, these servo circuits generate a focus error signal corresponding to the focal deviation of the light beam A and a tracking error signal corresponding to the positional deviation of the light beam with respect to the guide groove from the output signal of the pickup 13, and perform the following based on each error signal. The objective lens (not shown) of the pickup 13 is controlled to move vertically and radially to the signal recording surface of the disk 11, so that the focus of the light beam A is always focused on the signal recording surface of the disk 11. Focus servo and tracking servo are provided to irradiate A onto the guide groove or signal train. Further, the pickup 13 can be moved in the radial direction of the disk 11 by a feed motor 14 following the tracking servo, and can also be moved forcibly.

Further, in the lower part of the light transmitting portion 111 of the disk 11 in the figure, a long light [15] is provided in the radial direction of the disk 11. This light source 15 generates a light beam B, and irradiates this light beam B to the light receiving section 16 through the light transmitting section 111. The light-receiving section 16 includes a plurality of light-receiving elements (for example, photodiodes) having the same width over a position facing the light source 15 at the upper part of the disk 11 in the figure as well as an area facing the movement range of the pickup 13.
are arranged in the radial direction of the disk 11. On the other hand, the light beam A irradiated from the pickup 13 hits the signal recording surface of the disk 11 and is partially reflected, returns to the pickup 13 and is used for signal reproduction as described above, but a portion of it is transmitted through the disk 11. The light is then irradiated onto the light receiving section 16.

For the parallel data charged and converted by each light receiving element of the light receiving element 8I116, the data of the part irradiated with light by the head amplifier 18 of the position detection circuit 19 is '1', and the other data is '°O'. After being adjusted so that
The signal is supplied to the shift register 19.

Each of the shift registers 19 is of a parallel input/serial output type, and each time the clock pulse CP from the clock pulse generation circuit 20 is input, the data from the light receiving element is sequentially converted into serial data from the disk center side and output. . The serial data output from the shift register 19 is supplied to a rising edge detection circuit 21 and a falling edge detection circuit 22. The rising edge detection circuit 21 detects the rising edge of the input signal and generates a trigger pulse.
0 counter 23. Further, the falling edge detection circuit 22 detects the falling edge of the input signal and generates a trigger pulse, and this trigger pulse is supplied to the second counter 24. These first and second counters 23 and 24 each count the clock pulse CP from the clock pulse generation circuit 20 from the time when the trigger pulse is first input, and count the count value when the next bird inputs the pulse. Each count value is supplied to a first and second divider 25, 26, respectively.

These first and second dividers 25 and 26 each calculate 1/2 of the above count value, and the calculated values are respectively supplied to an adder 27 and added. The output of this adder 27 is taken out as position data corresponding to the light beam irradiation position.

The principle of operation of the above configuration will be explained below with reference to FIG. 2.

In FIG. 2(a), two peak points m and n of the signal
Consider the case of finding interval 2. First, if the points at which a certain predetermined level Y crosses the signal X are a, b, C, and d, then the following equation holds true.

β-n-m ~ -= + - Here, if the peak curves of the signal X are bilaterally symmetrical, then the following is true. That is, when the light beams A and B are respectively irradiated across a plurality of light receiving elements of the light receiving section 16, the above principle can be used to determine the accurate distance between the respective light beam irradiation positions.

That is, the light beam A is directed to the light receiving section 16.

Assuming that B is irradiated as shown in FIG. 3(a), the output of each light receiving element is equivalently sent to the shift register 19 as shown in FIG. 3(b). Here, when the serial data in the shift register 19 is scanned by the lock pulse CP as shown in FIG. 5(C), two pulses as shown in FIG. 2(d) are obtained.

On the other hand, the first and second counters 23 and 24 generate a load pulse as shown in FIG. 10(d) from the input clock pulse CP, and reset the count value when this load pulse is generated. . This load pulse generation timing is set when the shift register 19 takes out data on the disk center side.

When the serial data signal outputted from the shift register 19 by the above O-clock pulse CP is supplied to the rising edge detection circuit 21 and the falling edge detection circuit 22, the rising edge detection circuit 21 outputs the signal as shown in FIG. Two pulses synchronized with the rising edge of the input signal are outputted, and two pulses synchronized with the falling edge of the input signal are outputted from the falling edge detection circuit 22, as shown in FIG. 3(g). Here, the generation positions of the two pulses output from the rising edge detection circuit 21 are a and C, respectively, and the generation positions of the two pulses output from the falling edge detection circuit 22 are a and d, respectively. .

The outputs of the respective edge detection circuits 21 and 22 are the first
and a second counter 23,24. The first counter 23 starts counting when the first pulse is input, and outputs a count value when the next pulse is input.

As a result, the distance C-a between a and C is determined.

The second counter 24 similarly starts counting when the first pulse is input, and outputs a count value when the next pulse is input.

As a result, the distance d-b between b and 6 can be found. Each count value output from each counter 23, 24 is processed into 1/2 by first and second dividers 25, 26, respectively. This can be easily done by a 1 bit shift. The arithmetic processing results of the first and second dividers 25 and 26 are added together by an adder 27. In other words, this addition result is the calculation result of equation (1), and corresponds to the distance 2 between the centers of the light beams A and B on the light receiving section 16. This distance λ is equal to the distance between the light-transmitting hole 111 of the disk 11 and the irradiation position of the light beam A.

Here, if there is an eccentricity in the guide groove or signal train of the disk 11, the light beam A irradiated from the pickup 13 moves in the radial direction of the disk 11 in accordance with the eccentricity, so the irradiation position with respect to the light receiving section 16 also moves. do. However, the center of the guide groove or signal row and the light transmitting portion 11
1, the irradiation position of the light beam B on the light receiving section 16 also changes according to the eccentricity of the disk.

Therefore, the distance between the irradiation positions of the light beams A and B on the light receiving section 16 is constant regardless of disk eccentricity. In other words, the device data constituted by the adder 27 also does not include error components due to disk eccentricity.

Therefore, by using the light beam irradiation position detection device configured as described above, it is possible not only to eliminate errors caused by disk eccentricity, but also to ensure that each light beam is irradiated onto the light receiving section across multiple light receiving elements. However, since the distance between the centers can be determined, it is possible to detect the light beam irradiation position with great accuracy. Furthermore, by increasing the number of light receiving elements in the first and second light receiving sections, even more accurate position information can be obtained.

Note that this invention is not limited to the above embodiments,
For example, as shown in FIG. 4, the light receiving section 16 is arranged along the moving direction of the pickup 13,
A part A' of the light beam A is taken out from the pickup 13 and irradiated, and a light source 15 is provided above the disk 11 in the figure, and the light beam B from this light source 15 is transmitted through the light-transmitting hole 111 of the disk 11. Even if the light beam B is irradiated onto the light receiving section 16, the irradiation position of the light beam B on the disk 11 can be detected in the same manner as in the above embodiment. This configuration is very effective when the optical transmittance of the disk 11 is low.

In the above embodiment, a photodiode was used as each light-receiving element of the light-receiving section 16, but the resolution can be further improved by using a multi-pixel image sensor such as a COD or an amorphous silicon contact sensor. Furthermore, if a non-divided light receiving element such as a PSD is used, it is possible to determine even the guide groove or signal train irradiated with the light beam.

[Effects of the Invention] As detailed above, according to the present invention, the light beam irradiation position can be detected extremely accurately without errors due to eccentricity of the guide groove of the disk or the signal train. equipment can be provided.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the light beam irradiation position detection device according to the present invention, Fig. 2 is a waveform diagram for explaining the operating principle of the embodiment, and Fig. 3 is the operation of the embodiment. FIG. 4 is a configuration diagram showing another embodiment of the present invention, and FIGS. 5 and 6 are configuration diagrams each showing a conventional light beam irradiation position detection device. 11...Disk 111...Light transmitting section, 12...
D, ISKU MOTOR, 13...Pickup, 14...
・Feed motor, 15... Light source, 16... Light receiving section, 1
7...Position detection circuit, 18...Head amplifier, 19
...Shift register, 20...Clock pulse generation circuit, 21...Rising edge detection circuit, 22...
Falling edge detection circuit, 23.24... counter,
25, 26...divider, 21... adder. Applicant's agent Patent attorney Takehiko Suzue et al. Figure 3 Figure 4

Claims (1)

[Claims] A disk formed with a ring-shaped light transmission control section having the same center as a tracking guide groove formed on a signal recording surface or a signal train having a different reflectance according to an information signal, and a radial direction of this disk. The information signal is recorded on the disk by irradiating the guide groove with a light beam that changes according to the information signal while moving in the radial direction of the disk, or the light beam of a predetermined wavelength is irradiated onto the disk while moving in the radial direction of the disk. a pickup that reads the information signal recorded on the disk by receiving the reflected light of the light beam changed by the signal train; and a pickup that irradiates light near a light transmission control section on one side of the disk. a light-receiving section including a plurality of light-receiving elements of the same size disposed at a position facing the light source on the other side of the disk and having the same size in the movement direction of the pickup; a beam irradiation means for irradiating a part of the light beam generated by the pickup onto the light receiving section; and a beam irradiation means that detects the output level state of each light receiving element of the light receiving section and determines the light irradiation position from the light source and the light from the pickup. A position calculating means for calculating a light beam irradiation position relative to the light transmission control section of the disk by determining each center of the beam irradiation position and calculating a distance between the centers. Light beam irradiation position detection device.