WO2001037270A1

WO2001037270A1 - Disk-like recording carrier and optical recording/reproducing apparatus comprising the same

Info

Publication number: WO2001037270A1
Application number: PCT/JP2000/008062
Authority: WO
Inventors: Masayoshi Shioya; Yasumori Hino; Kazumasa Hirano
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 1999-11-17
Filing date: 2000-11-15
Publication date: 2001-05-25
Also published as: JP2001143328A

Abstract

An optical recording/reproducing apparatus for adjusting the state of a beam of light so that the jitter of the reproduced signal may be a minimum by applying a bias voltage to a focusing control system. A disk-like recording carrier (21) having a width of pits and an interval in the radial direction the ratios of which to the spot size of the recording/reproducing light beam are predetermined. The focused state of the light beam on the recording carrier is adjusted so that the signal amplitude produced by a pit may be a maximum. Thus, without recording a signal on a recording carrier in advance, the focused state of the light beam is optimized, thereby shortening the starting time of the apparatus.

Description

Description Disc-shaped record carrier and optical recording / reproducing apparatus using the same

The present invention relates to a disc-shaped record carrier on which information is recorded by a light source such as a laser and / or from which the recorded information is reproduced, and an optical disc for recording information on the record carrier and reproducing the recorded information. The present invention relates to a type recording / reproducing apparatus. Background art

Conventionally, a disc-shaped record carrier that rotates at a predetermined number of revolutions is converged and irradiated with a light beam generated from a semiconductor laser mounted on an optical pickup using an objective lens or the like, and the information recorded on the record carrier is Optical reproducing devices for reproducing are known.

A record carrier used in such an optical reproducing apparatus has a surface run of soil 100 / m to soil 200im due to a warp caused by the record carrier itself, a tilt caused by the device, and the like. On the other hand, since the depth of focus of the objective lens that converges the light beam on the record carrier is narrower than 1 m, the light beam output from the optical pickup must be focused properly on the record carrier. A focus error signal indicating the convergence state of the light beam on the record carrier is detected, and the objective lens is driven in the direction of moving toward and away from the record carrier in accordance with the focus error signal. A focus control system is needed to maintain the beam (ie, to make the light beam properly converge on the record carrier).

Further, the above-mentioned record carrier is provided with a fine pit row (track) having a pitch of 0.74 to 1.6 m in a spiral shape. Reproduction of the signal recorded thereon is performed by receiving reflected light from the record carrier with a photodetector while performing tracking control so that the light beam is always positioned on a pit row (track).

The focus error signal is also obtained from the reflected light from the record carrier. As a method for detecting the focus error signal from the reflected light, the astigmatism method is often used.

In the astigmatism method, a photodetector divided into four by two orthogonal straight lines is installed at a position where the cross section of the reflected light of the astigmatic optical system becomes circular when the record carrier is at the focal position of the objective lens Then, the force error signal (FE) can be detected by combining the four detection signals A, B, C, and D obtained from the four divided photodetectors by an arithmetic circuit or the like. Here, of the four detection signals A, B, C, and D, A and B and C and D are detection signals output from the cells of the photodetector located at diagonal positions.

In an astigmatism optical system, when the record carrier is at the focal position of the objective lens, the beam cross section on the photodetector divided into four is circular, and the four detection signals A, B, C, and D are (A + B) = (C + D). If the record carrier is closer to the objective lens than the focal position of the objective lens, the beam cross section on the four-divided photodetector becomes a diagonally long ellipse, and the detection signals A, B, C, and D become (A + B)> (C + D). Also, when the record carrier is farther from the objective lens than the focal position of the objective lens, the beam cross section on the photodetector divided into four parts becomes a long circle in the diagonal direction orthogonal to the major axis direction of the above-mentioned ellipse, The detection signals A, B, C, and D are (A + B) and (C + D). From the above, as the focus error signal FE, a calculation of FE = (A + B)-(C + D) can be performed to obtain a focus error signal indicating the convergence state of the light beam on the record carrier.

However, between the beam incident on the photodetector divided into four and the photodetector The focus error signal (FE) described above is caused by the position deviation of the optical detector, the variation in the sensitivity of each photodetector divided into four, and the variation in the amplification factor of the amplifier that amplifies the signal output from each photodetector. In some cases, the convergence state of the light beam on the record carrier may not be optimal even if becomes zero.

Therefore, for example, in a CD player or the like, a bias (offset) voltage is applied to the focus error signal to change the convergence state of the light beam, and adjustment is performed so that the jitter of the reproduced signal is optimized. The bias voltage is adjusted by the following procedures (1) to (4) (see Japanese Patent Application Laid-Open No. 8-77579).

(1) Focus control is performed on the objective lens with respect to the record carrier, and tracking control is performed so that the light beam spot by the objective lens is always positioned in the pit row on the record carrier.

(2) While applying a bias voltage in a direction in which the objective lens approaches the record carrier, the error rate of the reproduced signal is monitored, and the bias voltage V1 when the error rate reaches a predetermined limit value is stored.

(3) Monitor the error rate of the reproduced signal while applying a bias voltage in a direction in which the objective lens moves away from the record carrier, and store the bias voltage V2 when the error rate reaches a predetermined limit value.

(4) Calculate the value of V = (V 1 + V 2) 2 from the stored VI and V 2, and apply this value V to the focus control system as the optimal bias voltage value. The adjustment requires that information for measuring the error rate be recorded on the record carrier in advance. That is, in the case of an unused recording / reproducing record carrier, there is a problem that the bias voltage cannot be adjusted because no information is recorded on the record carrier. In addition, when trying to perform the above-described bias voltage adjustment on an unused recording / reproducing record carrier, it is necessary to provide a special area on the record carrier and perform information recording in advance, and then adjust the bias voltage. There is a problem that the start-up time of the device increases.

Furthermore, the method using the error rate of the reproduction signal requires an error rate measurement system that is not used in the normal operation of the optical recording / reproducing apparatus, and has a problem that the apparatus becomes complicated and expensive. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is unnecessary to previously record information for adjusting a bias voltage, thereby shortening a start-up time of an apparatus, and a circuit for measuring an error rate of a reproduced signal. It is an object of the present invention to provide a disc-shaped record carrier and an optical recording / reproducing apparatus which can optimize a convergence state of a light beam without using the same.

In order to achieve the above object, the present invention has the following configuration.

The disc-shaped record carrier of the present invention is a disc-shaped record carrier that is arranged radially along the center line of a pit force concentric or spiral virtual track, wherein The width of the pit in the radial direction is set to a predetermined ratio with respect to a spot size of a light beam for recording information on the record carrier or reproducing the recorded information. According to this configuration, by setting the interval or width in the radial direction of the pit to a predetermined ratio with respect to the spot size of the light beam, when the light beam passes over the pit and when the light beam passes through the pit When passing between the ports, the signal amplitude detected from the pit can be made substantially equal. As a result, the convergence state of the light beam is optimized by operating the focus control system without operating the tracking control system. Therefore, it is possible to detect the signal amplitude based on the pit necessary for the above. In the above configuration, it is preferable that a radial width of the pit is 0.5 times or more of a spot size of the light beam. According to such a configuration, it is possible to always secure a signal amplitude of 85% or more of the maximum detectable signal amplitude based on the pit.

Further, in the above configuration, it is preferable that the interval between the pits in the radial direction is 1.4 times or less the spot size of the light beam. In particular, if the distance between the clock pits in the radial direction is set to 1.4 times or less of the spot size of the light beam, the light beam will pass through between the clock pits. It is possible to obtain a signal amplitude of 90% or more of the signal amplitude based on the pit obtained when the beam passes over the clock pit.

Further, the optical recording / reproducing apparatus of the present invention provides a light converging device that converges a light beam on a disc-shaped record carrier on which pits are arranged at predetermined intervals along the center line of a concentric or spiral virtual track. Means, focus control means for controlling the position of the light convergence means so that the light beam is brought into a predetermined convergence state on the record carrier, and signal amplitude based on the pits from reflected light from the record carrier. And a convergence state of the light beam is changed so that an output of the amplitude detection means becomes a predetermined value. According to such a configuration, it is possible to adjust the convergence state of the light beam so that the signal amplitude based on the pit, which is the output value of the amplitude detection means, becomes a predetermined value.

In the above configuration, it is preferable that the amplitude detecting means includes an averaging means for averaging and outputting a signal amplitude based on the detected plurality of pits. According to this configuration, the signal amplitude detected when the light beam passes over the pit and when the light beam passes between the pits changes. It is possible to adjust the convergence state of the light beam using the signal amplitude based on.

In the above configuration, the apparatus further comprises tracking control means for causing the light beam to follow the center line of the virtual track, and operating the tracking control means so that the output of the amplitude detection means becomes a predetermined value. It is preferable to change the convergence state of the beam. According to this configuration, by operating the tracking control means, the light beam can pass through a predetermined position with respect to the pit (on the clock pit or at an intermediate position between the wobbled pits). Therefore, it is possible to more stably adjust the convergence state of the light beam by reducing the fluctuation of the signal amplitude based on the signal.

In the above configuration, it is preferable that the predetermined value is a maximum value of a signal amplitude based on the pit. That is, by adjusting the convergence state of the light beam so that the signal amplitude based on the pit becomes maximum, it becomes possible to minimize the jitter of the reproduced signal obtained from the optical disk. Therefore, it is possible to adjust the convergence state of the light beam more easily and faster than in the conventional method of measuring the error limit value of the reproduction signal. Also, since there is no need to provide a circuit for measuring the error rate of the reproduced signal, the device configuration can be simplified.

Further, in the above configuration, the pits may be formed as wobble pits which are allocated to the inner and outer peripheral sides with respect to the center line of the virtual track. According to such a configuration, among the pits provided on the record carrier, even if the amplitude of the signal based on the wobbled pits distributed and arranged on the inner and outer peripheries with respect to the center line of the track for tracking control is used, The convergence state of the beam can be adjusted to a predetermined state.

Further, in the above configuration, the pit may be a center of the virtual track. Clock pits for generating clock signals arranged at predetermined intervals on the line can also be used. According to such a configuration, among the pits provided on the record carrier, the convergence state of the light beam can be adjusted to a predetermined state by using the clock pit provided for generating the clock signal. .

Further, the optical recording / reproducing apparatus of the present invention includes: a light converging means for converging a light beam on the disc-shaped record carrier of the present invention; and Focus control means for controlling the position of the light converging means, and amplitude detecting means for detecting a signal amplitude based on the pit from the reflected light from the record carrier, wherein the output of the amplitude detecting means has a predetermined value. The convergence state of the light beam is changed so that According to such a configuration, the optimum value of the bias voltage applied to optimize the convergence state of the light beam on the record carrier can be determined based on the signal amplitude based on the pit. As a result, since it is not necessary to record information for adjusting the bias voltage on the record carrier in advance, the start-up time can be reduced. In addition, the apparatus can be simplified because the error rate measurement system required when adjusting the bias voltage based on the error rate of the reproduction signal is not required. Further, the convergence state of the light beam can be optimized only by operating the focus control system without operating the tracking control system. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a perspective view showing the entire configuration of a disc-shaped record carrier of the present invention, and FIG. 1B is an enlarged plan view schematically showing a state of formation of a pit on a surface.

FIG. 2 is a diagram showing the relationship between the ratio of the spot width to the spot size of the light beam and the signal amplitude.

FIG. 3 is a diagram illustrating the relationship between the ratio of the interval of the clock pit in the radial direction to the spot size of the light beam and the signal amplitude. FIG. 4 is a block diagram showing the configuration of the optical recording / reproducing apparatus of the present invention.

5A, 5B, and 5C are diagrams illustrating the operation of the astigmatism optical system of the optical recording / reproducing apparatus of the present invention.

FIG. 6 is a diagram showing a pit and a signal waveform detected from the pit. FIG. 7 is a block diagram showing a configuration of a detection circuit of the optical recording / reproducing apparatus of FIG.

FIG. 8 is a diagram showing the relationship between the offset voltage, the amount of jitter of the reproduced signal, and the signal amplitude value of the clock pitch. BEST MODE FOR CARRYING OUT THE INVENTION

1A and 1B are configuration diagrams of a disc-shaped record carrier 21 of the present invention. FIG. 1A is a perspective view showing the entire configuration, and FIG. 1B is a schematic diagram showing a pit formation state on a surface. FIG.

As shown in FIG. 1A, a disc-shaped record carrier (hereinafter referred to as an optical disc) 21 has a recording film 2 laminated on a substrate 1, and a spiral virtual track 3, 4 is formed. One round (360 °) of tracks 3 and 4 is divided into 128 segments 5.

FIG. 1B schematically shows a state of formation of a pit in one segment. In the figure, the horizontal direction on the paper indicates the track circumferential direction, and the light beam spot moves from left to right on the paper. Each segment 5 includes a clock pit 6 for generating a synchronizing signal in the direction of travel of the light beam spot, a wobbled pit 7 and 8 for obtaining a tracking signal, and address data or predetermined data. Address pits 9 in which information is distributed in units of 1 bit and areas where additional recording and erasing of information or signals can be performed Areas 10 are provided in order. The pebble pits 7 and 8 are formed at equal distances from the center line of the virtual tracks 3 and 4 to the inner and outer radial sides in the radial direction. The arrangement of the pebble pits 7, 8 differs between adjacent virtual tracks when viewed along the direction of movement of the light beam spot. In FIG. 1B, the arrangement of the pebble pits 7, 8 with respect to the center line of the virtual track is shown. Indicates the virtual track as 3 and 4.

In the optical disk 21 shown in FIGS. 1A and 1B, the radial width of the pits 6, 7, 8, and 9 and the radial interval between the clock pits 6 are light beams converged on the optical disk 21. The spot size is set so as to have a predetermined ratio with respect to the spot size (the width at which the relative intensity of the laser beam output from the objective lens 33 of the optical recording / reproducing apparatus in FIG. 4 described below is 50%). I have.

The depth of the pits 6, 7, 8, and 9 is set to, for example, 5 for the wavelength λ of the laser beam, and the circumferential length of the pit is 0.8 times the spot size of the light beam. When the radial width of the pit is changed with respect to the spot size of the light beam with the pit interval in the radial direction set to be equal to the spot size of the light beam, the signal amplitude based on the pit becomes It changes as shown in Figure 2.

In FIG. 2, the horizontal axis represents the ratio of the radial width of the pit to the spot size of the light beam, and the vertical axis represents the signal amplitude as a relative value with the maximum value being one. When the pit interval is set to a width equal to the spot size of the light beam, the signal amplitude is approximately equal between the case where the light beam passes over the pits (solid line) and the case where the light beam passes between the pits (dotted line). Can be obtained. Also, if the pit width is 0.5 times or more as large as the spot size of the light beam, it is possible to always detect a signal amplitude of 85% or more of the maximum detectable amplitude. The depth of the clock pit 6 is set to λ / 5 with respect to the wavelength λ of the laser beam, and the circumferential length of the clock pit 6 is set to 0.8 times the spot size of the light beam. When the radial spacing of clock pits 6 is made equal to the spot size of the light beam, and the radial spacing between clock pits 6 is changed with respect to the spot size of the light beam, the signal amplitude based on the pits is It changes as shown in 3.

In FIG. 3, the horizontal axis represents the ratio of the radial spacing of the clock pit 6 to the spot size of the light beam, and the vertical axis represents the signal amplitude as a relative value with the maximum value being one. If the radial distance between the clock pits 6 is set to 1.4 times or less the spot size of the light beam, even if the light beam passes between the clock pits 6 (dotted line). However, when the light beam passes over the clock pit 6 (solid line), it is possible to obtain an amplitude substantially equal to the signal amplitude obtained (90% or more).

As described above, by setting the radial width of the clock pit 6 and the radial interval between the clock pits 6 so as to have a predetermined ratio to the spot size of the light beam, the light beam is In this case, it is possible to detect substantially the same signal amplitude when the light beam passes over the pit and when the light beam passes between the pits.

FIG. 4 is a block diagram of the optical recording / reproducing apparatus of the present invention for recording / reproducing a signal on / from the optical disk 21 of FIG. In the figure, 21 is an optical disk shown in FIG. 1A, and 32 is an optical head for recording information on the optical disk 21 or reproducing information recorded on the optical disk 21. Light generated from a light source provided inside the light head 32 is collected on the optical disk 21 by the objective lens 33.

49 is a quadrant photodetector for detecting a focus error signal, and 35 and 40 are photodetectors for detecting a signal recorded on an optical disc 21 It is. The photo detectors 35, 40, 49 are mounted inside the optical head 32.

The optical head 32 is configured to be able to be transported in the radial direction of the optical disk 21 by the feed mode 34.

The optical disk 21 is mounted on a spindle motor (not shown) and rotates at a predetermined rotation speed. A light beam output from a semiconductor laser (not shown) mounted on the optical head 32 is converged and irradiated onto the optical disk 21 by the objective lens 33.

The reflected light from the optical disk 21 is split by an optical system (not shown) provided inside the optical head 32. One of the divided reflected lights passes through an astigmatic optical system (not shown), and then irradiates a photodetector 49 divided into four parts. The other reflected light is an analyzer (not shown). After passing through the above, the light detectors 35, 40 for recording signal detection are irradiated.

The photodetector 49 is installed at a position where the cross section of light passing through an astigmatism optical system (not shown) becomes circular when the recording film 2 of the optical disk 21 is at the focal position of the objective lens 33. ing.

Next, the operation of the astigmatism optical system will be described with reference to FIGS. 5A, 5B, and 5C.

When the recording film 2 of the optical disc 21 is at the focal position of the objective lens 33, the beam cross section 31 on the photodetector 49 becomes circular as shown in FIG. 5A. Therefore, the detection signals A, C, D, and B respectively output from the four cells 36, 37, 38, 39 constituting the photodetector 49 are (A + B) = (C + D).

When the recording film 2 of the optical disc 21 is closer than the focal position of the objective lens 33, the beam cross section 31 on the photodetector 49 becomes an ellipse long in the diagonal direction as shown in FIG. 5B. . Therefore, the four cells 36, 37, 38, 3 The detection signals A, C, D, and B respectively output from 9 are (A + B)> (C + D).

Further, when the recording film 2 of the optical disk 21 is further away from the focal position of the objective lens 33, the beam cross section 31 on the photodetector 49 is orthogonal to the long axis of the ellipse in FIG. 5B as shown in FIG. 5C. Ellipse having a major axis in the direction of Therefore, the detection signals A, C, D, and B respectively output from the four cells 36, 37, 38, and 39 are (A + B) <(C + D).

As shown in FIG. 4, the output signals A and B of the cell 36 and the cell 39 on the photodetector 49 are added by the adder 43 and input to the differential amplifier 44. The output signals C and D of the cells 37 and 38 on the photodetector 49 are added by the adder 42 and input to the differential amplifier 44. Then, the differential amplifier 44 calculates F E = (A + B) − (C + D) to obtain a focus error signal F E indicating the convergence state of the light beam on the optical disk 21.

The focus error signal FE output from the differential amplifier 44 is input to the focus control circuit 45. The focus control circuit 45 adds the output signal of the adder 42 and the output signal of the adder 43 (that is, adds all the detection signals A, B, C, and D of the photodetector 49). It consists of a controlled AGC (Automatic Gain Adjuster) and a high-pass filter.

The output signal from the focus control circuit 45 is applied to the drive circuit 46 via the adder 51 and the SW circuit (switching circuit) 52, and the output signal of the drive circuit 46 is applied to the focus coil 53. . As a result, a current corresponding to the focus error signal FE flows through the focus coil 53, and the objective lens 33 is driven.

That is, the objective lens 33 is driven according to the focus error signal FE, and the light beam is formed on the optical disk 21 so that it always has a predetermined convergence state. Scrap control is performed. In FIG. 4, a SW circuit 52 is for setting the focus control system to an operation state or a non-operation state.

On the other hand, the other split light of the reflected light from the optical disc 21 passes through an analyzer (not shown) or the like, and then irradiates the photodetectors 35 and 40 for detecting recording signals. Light is distributed to the photodetectors 35 and 40 according to the direction of magnetization on the optical disc 21 by the action of the analyzer. Therefore, the information signal recorded in the form of the direction of magnetization on the optical disc 21 is detected by taking the difference between the output signal of the photodetector 35 and the output signal of the photodetector 40 (see FIG. Omitted). Signals are recorded at a very high density on the optical disk 21, and high-response elements are used for the photodetectors 35 and 40 for detecting the signals.

As shown in FIGS. 1A and 1B, in the optical disc 21 of the present invention, a synchronization signal is generated at the beginning of a segment 5 formed by dividing one round of the track into 128. There are provided a clock pit 6, wobbled pits 7 and 8 for obtaining a tracking signal, and an address pit 9 in which address data is dispersed for each bit. As mentioned above, these pits are extremely small, with a radial width of at least 0.5 times the spot size of the light beam and a circumferential length of 0.8 times the spot size. Have been.

In a pit configured in this manner, the reflected light from the pit portion is much smaller than the reflected light from portions other than the pit portion, so the presence or absence of the pit is determined by the amount of reflected light from the optical disk 21. It is possible to detect. In the present embodiment, the above-described detection of the pit is performed by adding the output signal of the photodetector 35 and the output signal of the photodetector 40 by the adder 41. The output signal of the adder 41 is input to the detection circuit 47.

Next, the operation of the detection circuit 47 will be described with reference to FIGS. FIG. 6A shows the clock pit 6, the wobbled pits 7, 8, and the address pit 9 on the virtual track 3 (or 4) shown in FIG. 1B. FIG. 6B shows the output signal waveform of the adder 41 corresponding to each pit.

FIG. 7 is a block diagram showing a configuration of the detection circuit 47.

When the signal waveform shown in FIG. 6 (b) is output from the adder 41, the clock bit detection circuit 54 constituted by a logic circuit or the like detects the clock bit 6 and outputs the detection signal to the PLL circuit 55. Output to

? 1 ^ circuit 55 outputs the pulse-like timing signal shown in Fig. 6 (c), operates the peak detection circuit 56 (see Fig. 7) at the timing shown in Fig. 6 (c), and 41 The peak value of peak 11 corresponding to clock pit 6 in the output signal waveform from Fig. 6 (Fig. 6 (b)), that is, the signal amplitude value Sc based on clock pit 6 is detected.

The timing signal output from the PLL circuit 55 is delayed for a predetermined time by the timer 59 (see FIG. 7), and then at the timing shown in FIG. 6 (d), the peak detection circuit 57 (see FIG. 7) To detect the peak value of the peak 12 corresponding to the wobbled pit 7 in the output signal waveform (FIG. 6 (b)) from the adder 41, that is, the signal amplitude value Swl based on the wobbled pit 7 .

Similarly, the timing signal output from the PLL circuit 55 is delayed for a predetermined time by the timer 60 (see FIG. 7), and then the peak detector 58 (see FIG. 7) at the timing shown in FIG. 6 (e). The peak value of the peak 13 corresponding to the wobbled bit 8 in the output signal waveform from the adder 41 (Fig. 6 (b)), that is, the signal amplitude value Sw2 based on the wobbled bit 8 is calculated. To detect.

Output signal Swl of peak detection circuit 57 and output signal of peak detection circuit 58 By calculating the difference between the signals Sw2, it is possible to detect a position shift signal between the light beam and the virtual track 3 (or 4), that is, a tracking error signal, and use this to perform tracking control. Although a well-known method can be used for the specific method, the description is omitted because it is not directly related to the present invention.

The output signal Sc of the peak detection circuit 56 is input to a control circuit 48 (see FIG. 4) composed of DSP and the like.

The control circuit 48 applies the offset voltage to the focus control system while monitoring the output signal S c of the peak detection circuit 56, until the output signal S c of the peak detection circuit 56 reaches a predetermined value. The convergence state of the light beam on the optical disk 21 is changed. Here, the predetermined value may be a value that maximizes the signal amplitude Sc based on the clock pit 6, or may be set to an arbitrary value that is convenient for the recording / reproducing device.

Next, the effect of adjusting the convergence state of the optical beam so that the output signal Sc of the peak detection circuit 56 is maximized will be described with reference to FIG. The signal amplitude based on the amount of jitter (reproduced signal jitter) when the signal recorded on the optical disk 21 is reproduced and the clock pit 6 with respect to the offset voltage applied from the control circuit 48 to the focus control system The relationship of Sc is roughly as shown in FIG.

From Fig. 8, the applied offset voltage that maximizes the signal amplitude Sc (solid line) based on clock pit 6 and the applied offset voltage that minimizes the reproduced signal jitter (dotted line) are almost the same. To minimize the signal jitter amount, an offset voltage value at which the signal amplitude Sc based on the clock pitch 6 is maximized may be applied to the focus control system.

Therefore, it is possible to adjust the convergence state of the light beam to an optimum state without providing a circuit for measuring the error rate of the reproduced signal, which is conventionally required. Since signal amplitude detection based on clock pit 6 can be performed by operating only the focus control system, the state of the light beam on optical disk 21 can be optimized before operating the tracking control system. The racking control system can be operated more stably.

Further, as described above, since the wobbled pits 7 and 8 are pits for detecting a positional shift between the light beam and the track, the light beam is located between the pit and the light beam between the pits. In some cases, the detected signal amplitude is set to change. However, the wobble pits 7, 8 can be set to the same width, the same depth, and the same length as the clock pit 6. Therefore, the signal amplitude based on the wobbled pits 7 and 8 is measured while the tracking control system is operating, and the convergence state of the light beam is adjusted so that the signal amplitude based on the wobbled pits 7 and 8 is maximized. It is possible to make adjustments so that the playback time is minimal.

Even when the tracking control system is disabled, the average value of the signal amplitude based on the wobbled pits 7 and 8 is detected, and the convergence state of the light beam is adjusted so that the average value is maximized. It can be adjusted to minimize the playback jitter.

The clock pit 6 and the wobbled pits 7 and 8 are formed at the stage of creating the optical disk 21. The signal amplitude based on such a pit is used to adjust the convergence state of the light beam, so that the conventional method is used. As described above, it is not necessary to perform the operation of recording the information for adjusting the focus state while the apparatus is being activated immediately before the adjustment. Therefore, it is possible to shorten the start-up time of the optical recording / reproducing apparatus.

The present invention is not limited at all by the above-described embodiment. In the above embodiment, the case where the pit depth is set to λ / 5 with respect to the wavelength λ of the laser beam has been described. However, the pit depth may be further increased or reduced. Is also good. Also, the case where the pit length is 0.8 times the spot size of the light beam has been described, but a shorter pit may be used. In the above embodiment, the focus error signal is detected using the astigmatism method. However, a focus error detection method called an SSD (spot size detection) or a focus error detection method using a knife edge is used. May be. In the above-described embodiment, an example in which the pits are formed radially along the spiral virtual track has been described. good.

The embodiments described above are all intended to clarify the technical contents of the present invention, and the present invention should not be construed as being limited to such specific examples. However, various modifications can be made within the spirit of the invention and the scope described in the claims, and the invention should be interpreted in a broad sense. Industrial applicability

In the disk-shaped record carrier of the present invention, the radial width of the pits and the radial distance between the pits are set at a predetermined ratio with respect to the spot size of the light beam for recording and reproduction. The signal amplitude detected from the pit can be made substantially equal between the case where the light beam passes over the pit and the case where the light beam passes between the pits. As a result, it is possible to detect the signal amplitude based on the pit necessary for optimizing the convergence state of the optical beam only by operating the focus control system without operating the tracking control system.

Further, the optical recording / reproducing apparatus of the present invention changes the convergence state of the light beam so that the output of the amplitude detecting means for detecting the signal amplitude based on the pit from the reflected light from the record carrier becomes a predetermined value. , The signal amplitude based on the pit is Therefore, it is possible to adjust the convergence state of the light beam to a predetermined value. Therefore, by using the disc-shaped record carrier of the present invention in combination with the optical recording / reproducing apparatus, the tracking control system operates. Before the adjustment, the convergence state of the light beam can be adjusted optimally, so that the operation of the tracking control system can be made more stable.

The clock pit and the wobbled pit are formed at the stage of producing the record carrier. When the convergence state of the optical beam is adjusted by using the signal amplitude based on such a pit, the adjustment is performed before the adjustment. It is not necessary to perform the operation of recording the information for adjusting the focus state during the start-up of the apparatus. Therefore, the start-up time of the optical recording / reproducing apparatus can be reduced.

Also, by searching for the maximum value of the signal amplitude based on the pit and adjusting the convergence state, it is possible to adjust the convergence of the light beam more easily and faster than the method that measures the error limit value of the reproduced signal. It is. Further, since there is no need to provide a circuit for measuring the error rate of the reproduced signal, the device configuration can be simplified.

Therefore, the present invention can be used as an inexpensive and easy-to-use record carrier and optical recording / reproducing apparatus.

Claims

The scope of the claims

1. Pitch force A disc-shaped record carrier arranged radially along the center line of a concentric or spiral virtual track, wherein the pitch in the radial direction of the pits or the width in the radial direction of the pits A disc-shaped record carrier, wherein the disc-shaped record carrier is set at a predetermined ratio to a spot size of a light beam for recording information on the record carrier or reproducing the recorded information.

2. The disc-shaped record carrier according to claim 1, wherein a radial width of the pit is at least 0.5 times a spot size of the light beam.

3. The disc-shaped recording medium according to claim 1, wherein a distance between the pits in a radial direction is not more than 1.4 times a spot size of the light beam.

4. The radial width of the pit is not less than 0.5 times the spot size of the light beam, and the radial spacing of the pits is equal to the spot size of the light beam. 2. The disc-shaped record carrier according to claim 1, wherein the size is 4 times or less.

5. Light converging means for converging a light beam on a disc-shaped record carrier on which pits are arranged at predetermined intervals along the center line of a concentric or spiral virtual track; Focus control means for controlling the position of the light converging means so as to be in a predetermined convergence state above, and amplitude detecting means for detecting a signal amplitude based on the pit from the reflected light from the record carrier. An optical recording / reproducing apparatus, wherein the convergence state of the light beam is changed so that the output of the amplitude detection means becomes a predetermined value.

6. The optical recording / reproducing apparatus according to claim 5, wherein the amplitude detecting means includes an averaging means for averaging and outputting a signal amplitude based on the detected plurality of pits.

7. A tracking control means for causing the light beam to follow the center line of the virtual track, and convergence of the light beam so that the output of the amplitude detection means becomes a predetermined value while operating the tracking control means. 7. The optical recording / reproducing apparatus according to claim 5, wherein the state is changed.

8. The optical recording / reproducing apparatus according to claim 5, wherein the convergence state of the light beam is changed so that the output of the amplitude detecting means is maximized.

9. The optical recording / reproducing apparatus according to claim 5 or 6, wherein the pit is a wobble pit arranged inward and outward with respect to a center line of the virtual track. .

10. The optical recording / reproducing apparatus according to claim 5, wherein the pit is a clock pit for generating a clock signal arranged at a predetermined interval on a center line of the virtual track. apparatus.

11. A light converging means for converging a light beam on the disc-shaped record carrier according to any one of claims 1 to 4, and the light so that the light beam is in a predetermined convergence state on the record carrier. A focus control means for controlling the position of the convergence means; and an amplitude detection means for detecting a signal amplitude based on the pit from the reflected light from the record carrier, wherein an output of the amplitude detection means has a predetermined value. An optical recording / reproducing apparatus characterized in that the convergence state of the light beam is changed as described above.