JPH09330522A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the deviation of focus accurately even if the light of unnecessary zero-order light or the like enters photodetector in a focus servo using a hologram. SOLUTION: When tracking control is not applied, the amount of reflected light receives the modulation of a disk groove at the period of a rotating period or less. A reflected-light-amount detecting means 8 forms the signal of the amount of the reflected light by using the output of a light detecting device 102. An averaging means 9 averages the signal of the amount of the reflected light at the time more than the rotating period. A convergence-state detecting means 51 compares the average signal and the threshold voltage larger than the maximum value of the amount of the reflected light at the defocussing time and detects the deviation of the focus control. An instructing device 52 outputs the focus control signal based on the on-track signal outputted from a tracking-state detecting means 53 and the detected signal of the convergence state and imparts the instruction to a focus control means 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device having an improved focus servo control function.

[0002]

2. Description of the Related Art Conventionally, a compact disc (hereinafter abbreviated as a CD) has been widely accepted as a read-only disc for consumer use. In recent years, an optical disk and an optical disk device capable of recording and reproducing have been proposed in the field of consumer audio / video. An example of this is a mini disk for audio (hereinafter abbreviated as MD) and the like.

Also, optical pickups incorporated in optical disk devices have been made smaller and lighter, and those using techniques such as holograms have been put to practical use. In such an optical pickup, the traveling direction of light can be changed by the hologram and the prism. Also, a photodetector for detecting an information signal, a photodetector for detecting a focus error signal,
Further, the photodetector and the like for detecting the tracking error can be arranged close to each other, and therefore the optical pickup can be further downsized.

One of the features of these optical disk devices is that they are more resistant to vibration than conventional LP record players. In order to make full use of this feature, it is important for a CD player to be provided with a detector for detecting the state of focus control, and to have a protective function to restart focus control even if focus control is lost.

In a read-only optical disk system such as a CD, some kind of information signal is always recorded on a track. Therefore, as disclosed in Japanese Patent Laid-Open No. 62-65241, the presence or absence of the information signal is detected. By doing so, it is possible to detect whether or not focus control is applied. However, in a system such as MD which is premised on recording and reproduction, the information signal is not always recorded on the track. For this reason, it is impossible to always detect whether or not the focus control is applied depending on the presence or absence of the information signal.

In an optical disk device using such an optical disk, the state of focus control is detected by the amount of light reflected from the optical disk, as disclosed in Japanese Patent Laid-Open No. 6-4878. In this example, a level comparator is provided, and this comparator compares the amount of reflected light with a predetermined threshold to detect whether or not the laser light is focused on the photodetector. The threshold value here is set to be lower than the minimum level at which light is diffracted and modulated by the track when the light is focused on the photodetector. By detecting whether or not the laser light is focused by such a photodetector, it is possible to check whether or not the focus control is applied.

[0007]

However, in the above conventional structure, when a plurality of photodetectors for signal detection are close to each other, such as an optical pickup using a hologram, they reach different positions during defocusing. The light should be
There is an inconvenience that the light is spread on the same plane as the light receiving surface of the photodetector, or is moved and incident. In this case, the amount of reflected light detected at the time of defocusing may be larger than the minimum level at which the light is focused on the photodetector and diffracted by the track and modulated. In this case, there is a problem that the threshold value, which is the reference value of the focus state, is exceeded even in the defocus state, and the focus control state cannot be detected correctly.

The present invention has been made in view of such conventional problems, and the amount of reflected light detected at the time of defocus is diffracted by the track when the light is focused on the photodetector. Even if it is above the lowest modulated level,
An object of the present invention is to provide an optical disc device capable of correctly detecting the state of focus control.

[0009]

In order to solve such a problem, the invention according to claim 1 of the present application is such that when an optical disk is rotated by a rotating means and information is recorded or reproduced through an optical pickup, While controlling the attitude of the focusing lens of the optical pickup to perform tracking control so that the laser beam follows the track of the optical disc,
An optical disc device for performing focusing control so that the laser beam is focused on a desired spot, a photodetector for irradiating the recording surface of the optical disc with the laser beam and receiving the reflected light, and a spot of the laser beam. Reflected light amount signal detection means for generating a reflected light amount signal of the track from a focus signal output from the photodetector when the optical disc is scanned along the track direction of the optical disc, and a reflected light amount signal output by the reflected light amount signal detection means. Is averaged over a predetermined time, and an averaged means for outputting an averaged signal and reflected light from the recording surface of the optical disc on the light receiving surface of the photodetector using the averaged signal value output by the averaged means. Focusing state detecting means for detecting whether or not focusing is performed, and focus control is revised based on the detection result of the focusing state detecting means. With determining whether or not to perform, it is characterized in that it comprises a command means for instructing the recording or reproduction of information on a track of the optical disc if the focus state, the.

According to a second aspect of the present invention, when the optical disc is rotated by the rotating means and information is recorded or reproduced through the optical pickup, the attitude of the focusing lens of the optical pickup is controlled so that the laser beam emits the laser beam. Tracking control to follow the track of
An optical disk device for performing focusing control so that the laser beam is focused on a desired spot, the hologram irradiating a laser beam on a recording surface of the optical disk and diffracting reflected light into at least 0th order light and ± 1st order light. A plate, a first photodetector for detecting 0th-order light diffracted by the hologram plate, a second photodetector for detecting + 1st-order light, and a third photodetector for detecting -1st-order light. And a photodetector including the laser beam spot, when the spot of the laser beam is scanned along the track direction of the optical disk, the second or third
A reflected light amount signal detecting means for generating a reflected light amount signal of a track from a plurality of focus signals output from the photodetector,
The reflected light amount signal output from the reflected light amount signal detecting means is averaged over a predetermined time, and an averaging means that outputs an average signal, and an average signal output from the averaging means and a predetermined threshold value are compared, Focusing state detecting means for detecting whether or not the reflected light from the recording surface of the optical disc is focused on the light receiving surface of the photodetecting device, and whether focus control is performed again based on the detection result of the focusing state detecting means. And a command means for instructing to record or reproduce information on the track of the optical disc in the focused state.

According to a third aspect of the present invention, when the optical disc is rotated by the rotating means and information is recorded or reproduced through the optical pickup, the attitude of the focusing lens of the optical pickup is controlled so that the laser beam emits the laser beam. Tracking control to follow the track of
An optical disk device for performing focusing control so that the laser beam is focused on a desired spot, the hologram irradiating a laser beam on a recording surface of the optical disk and diffracting reflected light into at least 0th order light and ± 1st order light. A plate, a first photodetector for detecting 0th-order light diffracted by the hologram plate, a second photodetector for detecting + 1st-order light, and a third photodetector for detecting -1st-order light. And a photodetector including the laser beam spot, when the spot of the laser beam is scanned along the track direction of the optical disk, the second or third
A reflected light amount signal detecting means for generating a reflected light amount signal of a track from a plurality of focus signals output from the photodetector,
The reflected light amount signal output from the reflected light amount signal detecting means is averaged over a predetermined time, and an averaging means that outputs an average signal, and an average signal output from the averaging means and a predetermined threshold value are compared, Focusing state detection means for detecting whether or not the reflected light from the recording surface of the optical disc is focused on the light receiving surface of the photodetector, and the reflected light quantity signal of the reflected light quantity signal detection means causes the laser beam to be in the focused state. When it is determined that the focus control is performed again based on the detection result of the offset addition amplification means for changing the threshold voltage applied to the focus state detection means and the focus state detection means, In the state, a command means for instructing recording or reproducing of information on the track of the optical disk is provided.

Further, in the invention according to claim 4, the commanding means cancels the averaging process when the tracking control is applied, and gives the signal of the reflected light amount signal detecting means to the focusing state detecting means to perform the tracking control. If the average is not applied, an averaging process is performed, and the averaging means is instructed to give the averaged value to the focusing state detecting means.

According to a fifth aspect of the present invention, in the photo-detecting device, the first photo-detector reads the information recorded on the track, and the second photo-detector outputs the focus signal. The third photodetector outputs a tracking signal.

Further, in the invention according to claim 6, the averaging means is characterized in that the time for averaging the reflected light amount signals is equal to or longer than the rotation cycle of the optical disk.

In the invention according to claim 7, the averaging means sets the time for averaging the reflected light amount signal to one cycle of the tracking error signal obtained from the second or third photodetector. It is characterized by.

Further, in the present invention, the averaging means averages the reflected light amount signal at the time when the tracking error signal obtained from the second or third photodetector is at or near 0. It is characterized by performing conversion.

According to a ninth aspect of the present invention, the averaging means uses the reflected light amount signal at a point at which the tracking error signal obtained from the second or third photodetector is at its maximum or in the vicinity thereof. It is characterized by performing averaging.

According to the tenth aspect of the present invention, the averaging means uses the reflected light amount signal at the time point at or near the point where the tracking error signal obtained from the second or third photodetector becomes the minimum. It is characterized by performing averaging.

Further, the invention according to claim 11 is characterized in that the averaging means averages the maximum value of the reflected light amount signal obtained from the reflected light amount signal detecting means and a value in the vicinity thereof. It is a thing.

According to the twelfth aspect of the invention, the averaging means averages the minimum value of the reflected light amount signal obtained from the reflected light amount signal detecting means and a value in the vicinity thereof. It is a thing.

In the thirteenth aspect of the present invention, the averaging means averages the reflected light amount signal at a time point at or near 0 of the AC component of the reflected light amount signal obtained from the reflected light amount signal detecting means. It is characterized by performing.

As described above, according to the first to third aspects, the amount of reflected light detected during defocusing is diffracted and modulated by the track of the disk when the light is focused on the photodetector. Even if it is higher than the minimum level, it is possible to detect whether or not the light is focused by averaging the modulation by the tracks and comparing it with a predetermined threshold value, and it is possible to correctly detect the state of focus control.

When the tracking control is applied, since the laser beam does not traverse the track, the modulation of the reflected light amount due to the diffraction of the track does not occur. Therefore, according to the configuration of the fourth aspect, the averaging process is canceled when the tracking control is applied. In this way, when the focus control is deviated from the state where the tracking control is applied, it can be detected in a shorter time that the focus state is not set.

Since the track of the disk is formed in a spiral shape, if the tracking servo is not applied,
Cross the track at least once per revolution. According to the configuration of the sixth aspect, the averaging means temporally averages the reflected light amount signal for a time period sufficiently longer than the rotation period, so that an average signal having a sufficiently small modulation component can be output.

According to the structure of claim 7, since the track is formed in a spiral shape, the track is crossed at least once in one rotation, so that the tracking error signal is temporally averaged in one cycle time. I am trying to make it. In this way, the averaging can be completed within the time required to traverse one track, and if focus control is lost, it can be detected in a shorter time that the focus state is not achieved.

According to the present invention, the tracking error signal is averaged in accordance with the reflected light amount signal at the point where the tracking error signal is 0, the maximum value, or the minimum value or the vicinity thereof, so that one track is formed. Since the averaging can be completed within the time that traverses, and the number or change of the values of the signal to be averaged is small, it can be detected that the focus state is not achieved in a shorter time when the focus control is deviated.

According to the eleventh to thirteenth aspects, by performing the averaging in accordance with the maximum value of the reflected light amount signal in the range of the averaging time, the maximum of the reflected light amount signal detected at the time of defocusing can be obtained. The difference between the level and the value increases,
It is possible to avoid malfunction due to the influence of noise or the like.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) An optical disk device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the optical disc apparatus of this embodiment centering on focus control. In FIG. 1, an optical disc 1 is a disc-shaped medium that is placed on a rotating unit 2 and rotates to record or reproduce information.

The traverse motor 3 is a motor for coarse movement positioning which applies a driving force to the traverse gear 4. The traverse gear 4 is a drive gear that meshes with the gear portion of the optical pickup 100 and moves the optical pickup 100 in the radial direction of the disc 1.

The optical pickup 100 comprises an integrated body 101,
Focusing lens 105, focus actuator 107,
The tracking actuator 108 is included. The integrated body 101 includes the photodetector 102 and the hologram 1.
03, a prism 104, and a laser light source (not shown), the laser light is emitted at the time of reading and recording of information, and the reflected light is received from the optical disc 1. The focusing lens 105 is attached on the optical path of the integrated body 101 and focuses the beam of the laser light source on the track of the optical disc 1. The focus actuator 107 is an actuator that controls the attitude of the focusing lens 105, which is finely mounted in the direction perpendicular to the information surface of the optical disc 1, and the tracking actuator 108 is finely movable in the radial direction of the optical disc 1.

The photo-detecting device 102 of the integrated body 101 receives the reflected light from the optical disc 1 inputted through the prism 104 and the hologram 103, and outputs the detection signal as the focus error signal detecting means 5 and the reflected light amount signal detecting means. 8 is output. Hologram 103 is optical disc 1
It is a hologram plate that diffracts the reflected light from the light into 0th order light, ± 1st order light and the like.

The photo-detecting device 102 has a plurality of photo-detectors arranged in a plane. The photo-detecting device 102 reads the information recorded on the optical disc 1 by using the 0th-order light and the focus signal and the It outputs a detection signal necessary for generating a tracking signal. The specific configuration will be described in the operation explanation part.

The focus error signal detecting means 5 inputs the signal of one photodetector group of the photodetector 102 to the non-inverting input terminal and inputs the signal of the other photodetector group to the inverting input terminal to detect the focus error. It is a means for generating a signal. The focus control means 6 is means for inputting a focus error signal and a first output of the command unit 52 described later, and generating a focus control signal using the loop error filter of the focus error signal according to the first output. .

The focus actuator driver 7 is
A drive current is applied to the focus actuator 107 of the optical pickup 100 according to a focus control signal output from the focus control means 6 to control the attitude of the focusing lens 105.

The reflected light amount signal detecting means 8 is a light detecting device 10.
The signal of one of the two photodetector groups and the signal of the other photodetector group are input, and the reflected light amount signal is detected by adding these two signals. When the reflected light amount signal output from the reflected light amount signal detection unit 8 is input to the averaging unit 9, the reflected light amount signal is sufficiently longer than the rotation cycle of the optical disc 1 in accordance with the second output generated by the command unit 52. It averages over time and outputs an average signal.

The reference power source 50 is a reference power source that outputs a predetermined threshold voltage Vth described later. Focusing state detection means 5
Reference numeral 1 compares the threshold voltage Vth with the average signal, and outputs a focus state detection signal that has a logical value "H" when the average signal is larger than the threshold voltage. When the focusing state detection signal and the output of the tracking state detecting means 53 described later are input, the command device 52 outputs the first output to the focus control means 6 and the second output to the averaging means 9. It is a control unit that does.

The tracking state detecting means 53 outputs a logical value "H" to the command device 52 when the light beam follows the track. Although detailed description is omitted because it is not directly related to the present invention, the light beam follows the track by detecting that the amplitude of the tracking error signal is below a certain level while the focus servo is being applied. The method of detecting that there is a general method is performed.

FIG. 2A is an optical path diagram in which the reflected light from the optical disk 1 reaches the integrated body 101. As shown in the figure, the reflected light from the optical disc 1 enters from the upper surface of the prism 104 and travels toward the lower surface through the hologram 103. The light split by the prism 104 is used for detecting RF signals and the like. Further, in order to control the laser power for stabilizing the output of the laser light source, a part of the output beam may be extracted and received by a photodetector (not shown). The reflected light emitted from the lower surface of the prism 104 is diffracted by the hologram 103 and separated into five light beams, and reaches the photodetector device 102 provided with a plurality of photodetectors.

FIG. 2B is an optical path diagram of reflected light when FIG. 2A is viewed in the direction of arrow V. Hologram 10
The light that has passed through 3 is in three focused states, and the light detection device 102
To reach the top. 0 when reflected light passed through hologram 103
The next light is focused at the o point which is the focal point. At the position of point a, the hologram 103 works to hit the photodetector 102 before the focus, and at the position of point b, hit the photodetector 102 after the focus. By arranging the photodetectors at these two positions, the focus error can be detected by the spot size detection method (hereinafter abbreviated as SSD method). By properly designing the diffraction pattern of the hologram 103, such a function can be realized.

Regarding the SSD method using a hologram,
Those disclosed in JP-A-63-229640 can be mentioned. In addition, it is generally known that the position of the focal point can be adjusted by designing the hologram, for example, "Applied Optics I" (1982: Asakura Publishing: Tatsuro Suzuki) 184.
See pages 192 to 192 for details.

FIG. 3 is an arrangement diagram showing types and areas of diffraction patterns on the hologram 103. This figure is shown in Figure 2 (b).
It is a top view of the diffraction pattern of the hologram 103 shown in FIG. 3, and the symbols as shown are attached to each pattern. Then, the same symbols are used to represent the regions in which light is diffracted in the same direction and the same relative position. G indicated by a great circle represents the range of the light spot of the reflected light. Since the detection is performed by the SSD method, the regions Fa and Fb are alternately arranged in a strip shape so that the light reaches the points a and b in FIG. 2B almost uniformly. The light in the area Fa is designed to reach near the point a, and the light in the area Fb is designed to reach near the point b. Similarly, area C1a, area C2a,
The light in the area D1a and the light in the area D2a reach the vicinity of point a, respectively. Area C1b, Area C2b, Area D1b, Area D2b
Light reaches near point b.

Regarding the hologram design, there is an optical pickup that performs such focus error detection by the SSD method and tracking error detection by the push-pull method. As one example of such an optical pickup, Japanese Patent Application No.
There is an optical pickup of No. 149231. In this way, the light receiving region is divided into strips, and the light utilization efficiency can be improved.

FIG. 4 is a block diagram of the photodetector 102.
FIG. 3 is a plan view seen from the side where the hologram 103 is located along the optical axis direction. In this figure, the position of the light spot when the reflected light from the optical disc 1 is focused on the photodetector 102 is shown by a circular or strip pattern. The laser light of the laser light source 121 is emitted in parallel with the paper surface of FIG. 4, and the direction is changed by the mirror 122 in a direction perpendicular to the paper surface. Then, the laser beam is incident on the recording surface of the optical disc 1 through the prism 104 of FIG.

Photodetectors 131 to 131 provided on the right side of FIG.
Reference numeral 136 is arranged so as to detect a focus error by the SSD method. Photodetectors 137 to 1 provided on the left side
40 is arranged so as to detect the tracking error signal by the push-pull method. The photodetectors 131 to 136 are arranged so as to detect the + 1st order light of the hologram 103, and the photodetectors 137 to 140 are −1 of the hologram 103.
It is arranged to detect the next light.

The first I / V converter 150 is the photodetector 1
It is a converter that adds the output currents of 32, 134 and 136 and converts it into a voltage. The second I / V converter 151 is a converter that adds the output currents of the photodetectors 131, 133, and 135 and converts it into a voltage. The outputs of the first I / V converter 150 and the second I / V converter 151 are signals for detecting a focus error, and are input to the focus error signal detection means 5 of FIG. To be converted. Further, these two signals are also input to the reflected light amount signal detection means 8 in FIG. 1 and converted into reflected light amount signals.

The third I / V converter 152 is the photodetector 13.
It is a converter that adds the output currents of 7 and 139 and converts them into a voltage. The fourth I / V converter 153 is a photodetector 138,
It is a converter that adds the current output of 140 and converts it into a voltage. The outputs of the third I / V converter 152 and the fourth I / V converter 153 are signals for detecting a tracking error signal. Although a description of the tracking control method will be omitted, it is assumed that a tracking error signal is generated by the push-pull method by taking the differential of these two signals to perform tracking control.

The light spot A indicated by a circle in FIG. 4 indicates the position of the 0th-order light spot where the reflected light from the optical disk 1 has passed through the hologram 103. On the other hand, strip-shaped light spots C1a, C2a, D1a, D2a, Fa, C1
b, C2b, D1b, D2b, and Fb indicate the positions of the light spots where the reflected light from the optical disc 1 passes through the hologram 103 and reaches from the areas of the same symbol.

The operation of the optical disk device of the present embodiment having the above configuration will be described. First, the case where the reflected light from the optical disc 1 is focused on the photodetector 102 will be described with reference to FIG. Consider a state in which the optical pickup 100 is moved in the radial direction of the optical disc 1 by the operation of the traverse gear 4, or the optical disc 1 is eccentrically attached to the rotating means 2 and tracking servo is not applied. In this case, since the reflected light is modulated by diffraction as it traverses the track, the reflected light amount signal output from the reflected light amount signal detecting means 8 is as shown in FIG. The average signal output from the averaging means 9 is shown in FIG.
It becomes like (b). In addition, I / V converters 152 and 153
The tracking error signal which is the differential signal of the output of FIG.
It becomes like (c). 5A, 5B, and 5C, the horizontal axis represents time, and the same position on the horizontal axis represents the same time point. The vertical axes represent the levels of the reflected light amount signal, the average signal, and the tracking error signal, respectively, and the same position represents the same level.

When the light beam is present on the guide groove whose width is ½ or more of the track pitch, the reflected light amount signal of FIG. 5 (a) becomes the level of the maximum point Pa, at which point the tracking error signal becomes As shown in FIG. 5C, the To point becomes 0. When the light beam is present on the portion between the guide grooves whose width is equal to or less than 1/2 of the track pitch, the reflected light amount signal becomes the level of the minimum point Pb, at which point the tracking error signal is Similarly, it becomes a To point of 0. FIG.
Point Pc in (a) is a point at an intermediate level between the maximum point Pa and the minimum point Pb of the reflected light amount signal, and at that time, the time at the maximum point Ta of the tracking error signal or the tracking error signal's point. It coincides with the time at the minimum point Tb. On the other hand, the average signal shown in FIG. 5B becomes the level Ph of the temporal average value of the reflected light amount signal as described later.

Next, a case will be described in which the distance between the focusing lens 105 and the optical disc 1 changes, and the reflected light from the optical disc 1 is not focused on the photodetector 102 but is defocused. FIG. 6 is an explanatory diagram showing an optical path of reflected light and a side surface of the photodetector device 102 when defocused. The same parts as those in FIG. 2 are designated by the same reference numerals. 2a in FIG.
The positions of the diffraction patterns were reversed at the points b and b,
In FIG. 6, the positions of the diffraction patterns are not inverted at points a and b. In this case, the reflected light passes through the hologram 103 and becomes 0
Subsequent light forms a large light spot centered on point o.
The light whose course has been changed by the hologram 103 strikes the photodetector 102 before focusing, and thus forms a large light spot centered around points a and b.

FIG. 7 is a plan view showing the position of the light spot on the photodetector 102 when the laser light is defocused. The same parts as those in FIG. 4 are denoted by the same reference numerals, and detailed description of the configuration is omitted. Compared to the case of FIG. 4, C1b and C1
It can be seen that the position of 2b and the position of D1b and D2b are interchanged.

As shown in FIG. 6, the light spot largely spreads on the light receiving surface of the photodetector 102, and the 0th-order light of the light spot A has a wider irradiation range than that shown in FIG.
Therefore, as shown in FIG. 7, the 0th-order light of the light spot A is incident on the photodetectors 131 to 136 for focus error detection. In this way, the light that should not be originally incident due to defocus is incident on the photodetectors 131 to 136, so that the first I / V converter 150 and the second I / V conversion are performed despite the defocus. The output voltage of the device 151 increases.

When the focus distance is the distance between the focusing lens 105 and the optical disc 1, FIG. 8A shows the relationship between the focus distance and the reflected light amount signal, and FIG. 8B shows the focus distance and the average signal. 8C, and FIG. 8C is a graph showing the relationship between the focus distance and the focus error signal.

When the distance between the focusing lens 105 and the optical disc 1 gradually increases as the distance from the O point where the focus error signal becomes 0 as shown in FIG. 8C, the defocus occurs as described with reference to FIG. Nevertheless, the first I / V
The output voltage of the converter 150 and the second I / V converter 151 once decreases and then increases again. Therefore, FIG.
As shown in (a), the level of the reflected light amount signal output from the reflected light amount signal detecting means 8 also decreases once and then increases again.

The focus error signal of the reflected light amount signal is 0.
Even at the O point at which P is changed, the track is modulated as described with reference to FIGS. 4 and 5, and therefore P in FIG.
The level is somewhere between the level indicated by the point a and the point indicated by the point Pb. On the other hand, the average signal shown in FIG. 8B is a signal obtained by averaging the reflected light amount signal for a time period sufficiently longer than the rotation period, and thus is not easily affected by the track modulation. Therefore, at the point O where the focus error signal becomes 0, the level becomes stable as indicated by Ph. The threshold voltage of the reference power supply 50 in FIG. 1 is indicated by Vth in FIG.

First, the case where the focus control is applied and the tracking control is not applied will be described. The averaging means 9 in FIG. 1 outputs an average signal of the Ph level. As shown in FIG. 8B, the focusing state detecting means 51 compares the average signal of the Ph level with the threshold voltage Vth. Since Ph> Vth here, the focusing state detection signal having the logical value “H” is obtained. Is output. Commander 52
Since the focus state detection signal has the logical value “H”, it is determined that the focus control is stable.

When the focus control is lost due to the vibration of the optical disk device or the like, defocusing occurs and the average signal falls below the level of Ph. The average signal is the threshold voltage V
When it becomes lower than th, the focusing state detecting means 51 outputs a focusing state detection signal having a logical value "L". Commander 5
In No. 2, since the focus state detection signal has the logical value "L", it is determined that the focus control is out. Commander 5 at this time
2 gives an instruction to the focus control means 6 using the first output to instruct to perform focus control again.

As described above, when the light is focused on the photodetector, even if the amount of reflected light detected at the time of defocus is larger than the minimum level diffracted and modulated by the track, the modulation by the track is averaged. It is possible to detect whether or not the light is focused and correctly identify the state of the focus control by converting it into a predetermined threshold voltage and comparing it.

Next, a case where the tracking control is applied to the guide groove having a width of ½ or more of the track pitch will be described. When the tracking control is applied, the track is not traversed, and the temporal change of the reflected light amount signal is smaller than that when the tracking control is not applied. The track width is 1 / the track pitch.
Since it is 2 or more, the reflected light amount signal is as shown in FIGS.
It becomes the level of Pa shown in (a).

The command unit 52 is the tracking state detecting means 5
When it is detected that the output of 3 is the logical value “H”, the second
The averaging means 8 is controlled by using the output of 1 to instruct not to perform averaging. In this case, the averaging means 8 outputs an average signal of Pa level. The focusing state detecting means 51 is
The average signal of the Ph level is compared with the threshold voltage Vth, and the focus state detection signal having the logical value “H” is output. Since the focusing state detection signal has the logical value "H", the command unit 52 determines that the focus control is stable.

Due to the influence of vibration on the optical disk device,
If focus control is lost, the defocused average signal falls below the Pa level. The speed at which the average signal drops at this time is faster because it is not performing averaging because it follows the track in the immediately preceding state.
When the average signal falls below the threshold voltage Vth, the focusing state detecting means 51 compares the average signal with the threshold voltage Vth,
A focus state detection signal having a logical value "L" is output. Since the focus state detection signal has the logical value "L", the command unit 52 determines that the focus control is out. Then, the command device 52 uses the first output to issue a command to the focus control means 6 to instruct to perform focus control again. As described above, when the focus control is deviated from the state where the tracking control is applied, it is possible to detect that the focus control deviates more quickly.

Next, various configuration examples of the averaging means and their operations will be described. FIG. 9 is a block diagram showing a specific example of the first averaging means 9. In the figure, the first oscillator 201 is an oscillator that generates a pulse signal at a frequency sufficiently higher than the frequency of a tracking error signal when crossing a track. The second oscillator 202 is an oscillator that generates a pulse signal with a period sufficiently longer than the rotation period of the optical disc 1. The AD converter 203 is the first oscillator 20.
This is a converter that converts the reflected light amount signal output from the reflected light amount signal detection unit 8 into a digital value in synchronization with the pulse signal of 1 and outputs the digital value to the addition storage unit 204. Addition memory 204
Is a circuit that adds the current storage value and the input digital value in synchronization with the pulse of the first oscillator 201, newly stores the addition result, and outputs the addition result to the divider 206. The counter 205 is a counter that counts the number of output pulses of the first oscillator 205 and outputs the current count value.

The divider 206 is a circuit that divides the value output from the addition memory 204 by the output value of the counter 205 in synchronization with the pulse signal output from the second oscillator 202. The division result here is output to the DA converter 207. DA
The converter 207 is a circuit that converts the output value of the divider 207 into an analog voltage in synchronization with the pulse signal output from the second oscillator 202. It should be noted that the addition storage device 20 is added at regular intervals.
4 and counter 205 are initialized. Switch 208
Is a circuit for switching to the output of the DA converter 207 if the second output of the command unit 52 is at H level, and switching to the output of the reflected light amount signal detecting means 8 if the second output is at L level.

As described above, the averaging means 9 averages the output of the reflected light amount signal 8 in a cycle sufficiently longer than the rotation cycle in response to the second output of the command unit 52, and outputs the output.

As described above, according to this embodiment, by providing the averaging means 9, the amount of reflected light detected at the time of defocus is diffracted and modulated by the track when the light is focused on the photodetector. Even if it is higher than the lowest level, the state of focus control can be correctly detected by averaging the modulation by the tracks and comparing it with a predetermined threshold to detect whether the light is focused.

If tracking control is being applied, the averaging means 9 instructs the averaging means not to perform averaging, so that when the focus control is out of focus while the tracking control is being applied, the focus is removed. The loss of control can be detected faster.

The averaging means 9 in the present embodiment.
In the above, the averaging is not performed for a time sufficiently longer than the rotation cycle, but an averaging means configured to perform the averaging during one cycle of the tracking error may be used. Also in this case, the configuration of the entire optical disk device is shown in FIG.
Since it is the same as, the detailed description will be omitted.

FIG. 10 is a block diagram of the second averaging means 10 for realizing the above-mentioned function. The same parts as those in FIG. 9 are denoted by the same reference numerals and detailed description thereof will be omitted. Here, a track crossing signal generator 210 is provided in place of the second oscillator 202 of FIG. Cross-track signal generator 21
Reference numeral 0 is a circuit that compares the tracking error signal with a reference voltage to generate a peak output of each pulse that is inverted at the 0 crossing point of the tracking signal as a first output pulse. The divider 206 and the DA converter 207 operate in synchronization with the output pulse of the cross-track signal generator 210.

As described with reference to FIG. 5, since the time of one cycle of the tracking error signal is the same as one cycle of the reflected light amount signal, the influence of the track modulation becomes sufficiently small.
The Pc level of the average signal becomes the same as the level at the Pc point.
Since the averaging means 10 has a shorter averaging time than the first averaging means 9 for averaging in the rotation cycle of the optical disc 1, it is possible to shorten the time until the focus control deviation is detected.

When the amplitude of the tracking error signal is small, the track crossing signal generator 210 operates the gate circuit 2 when the second output output from the command unit 52 is at the H level.
The switch 208 is switched through 12 to average the signals of the reflected light amount detection means 8. When the second output output from the command unit 52 is at the L level, the switching unit 208 is switched through the gate circuit 212, and the input signal of the averaging means 10 is passed through and supplied to the focusing state detecting means 11. In this way, when the amplitude of the tracking error signal is small due to defocusing or the like, the averaging means 10 malfunctions even if a pulse having a short cycle is generated in the first output pulse output from the track crossing signal generator 210 due to noise. Can be prevented.

As described above, the averaging means 10 performs averaging in one cycle time of the tracking error, so that the averaging time is longer than that of the averaging means 9 which averages in the rotation cycle of the optical disk 1. The time becomes shorter, and the time until the focus control deviation is detected can be shortened.

Although the first averaging means 9 described above performs averaging for a time period sufficiently longer than the rotation cycle of the optical disk 1, it depends on the reflected light amount signal when the tracking error signal is zero. You may use the averaging means which averages. In this case as well, the overall configuration of the optical disk device is the same as that shown in FIG.

FIG. 11 is a block diagram showing the configuration of the third averaging means 11 having such a function. The same components as those of the averaging means described with reference to FIGS. 9 and 10 are designated by the same reference numerals, and detailed description of the same components will be omitted. Here, a tracking error zero-cross signal generator 230 is provided in place of the first oscillator 201 of FIG. The tracking error zero-cross signal generator 230 compares the tracking error signal with a reference voltage, outputs a second output pulse to the gate circuit 232 for a certain period of time from the time when the comparison result changes, and outputs the second output pulse to the gate circuit 232 at the same timing. It is a circuit that outputs the output pulse as a clock signal to the AD converter 203, the addition storage unit 204, and the counter 205. A
The D converter 203 converts the reflected light amount signal into a digital value in synchronization with the first output pulse of the tracking error zero cross signal generator 230.

As described with reference to FIG. 5, at the point 0 of the tracking error signal, the reflected light amount signal reaches the maximum Pa point level or the minimum Pb point level. Further, since the time of one cycle of the tracking error signal is the same as one cycle of the reflected light amount signal, the influence of the modulation of the track becomes sufficiently small, and the DA converter 207 holds the voltage of the level at the point Pc. The output average signal has a constant level indicated by Ph.

Since the averaging means 11 has a shorter averaging time than the averaging means 9 for averaging in the rotation cycle of the optical disk 1, the time until focus control deviation is detected can be shortened. Further, since the processing is performed only near the zero crossing point of the tracking signal, the AD converter 203 can be used even if the conversion time is long, and the accuracy of the calculation can be improved.

When the amplitude of the tracking error signal is small, the tracking error zero cross signal generator 230 is generated when the second output output from the command unit 52 is at the H level.
Alternatively, the cross-track signal generator 210 gives the second output pulse to the switch 208 through the gate circuit 232 so that the signals of the reflected light amount detection means 8 are averaged. When the second output output from the command unit 52 is at the L level, the switching unit 208 is switched through the gate circuit 232, and the input signal of the averaging unit 10 is passed through and supplied to the focusing state detecting unit 11. By doing so, when the amplitude of the tracking error signal is small due to defocusing or the like, the tracking error zero-cross signal generator 230 is generated due to noise.
Alternatively, the averaging means 11 can be prevented from malfunctioning by inserting a pulse having a short cycle into the first output pulse of the track crossing signal generator 210.

As described above, by using the averaging means 11 for averaging the reflected light amount signal when the tracking error signal is at 0, the processing can be performed only at the 0 crossing point of the tracking signal. Therefore, the AD converter 203 can be used even if the conversion time is long,
Moreover, the accuracy of the calculation can be improved.

Next, the first averaging means 9 described above performs averaging for a time sufficiently longer than the rotation period, but performs averaging according to the reflected light amount signal when the tracking error signal is at the maximum. You may use an averaging means. In this case as well, the configuration of the entire optical disk device is the same,
The description of the same parts as those is omitted.

FIG. 12 is a block diagram showing the structure of the fourth averaging means 12 having such a function. The same reference numerals are used for the same components as the averaging means described in FIGS. 9 to 11, and detailed description will be omitted. Here, the addition memory 204, the divider 206, the second oscillator 2 as shown in FIG.
02 is abolished and a memory 221 and a tracking error maximum signal generator 220 are provided. The tracking error maximum signal generator 220 of FIG. 12 compares the tracking error signal with a reference voltage to perform AD conversion using the first output pulse as a clock at the maximum point of the tracking error signal.
It is a circuit that supplies the converter 203, the memory 221, and the DA converter 207, and also supplies a signal peak-held at the maximum point of the tracking error signal to the gate circuit 212 as a second output pulse. The AD converter 203 converts the reflected light amount signal into a digital value in synchronization with the first output pulse of the tracking error maximum signal generator 220. The storage device 221 is a storage device that holds the data output from the AD converter 203. The DA converter 207 is a circuit that converts the data output from the memory 221 into an analog signal.

As described with reference to FIG. 5, the level of the reflected light amount signal becomes the change center point Pc at the maximum point of the tracking error signal. Since the DA converter 207 DA-converts the level at the change center point Pc, the output signal has a constant level P.
h. The averaging means 12 has a shorter averaging time than the first averaging means 9 for averaging in the time of the rotation cycle of the optical disk 1, so that the focus control can shorten the time until the deviation is detected. Further, since the divider and the like are not used, the circuit of the averaging means can be simplified.

Even if the tracking error signal is configured to hold the level of the reflected light amount signal at the minimum point, it is possible to hold the level at the change center point Pc and keep the average signal at a constant level Ph. . In addition, by arranging to hold the level of the reflected light amount signal at both the maximum point and the minimum point of the tracking error signal, it is possible to perform averaging in a further half time, and to detect the focus control deviation. You can shorten the time.

When the amplitude of the tracking error signal is small and the second output output from the command unit 52 is at the H level, the second output pulse output from the tracking error maximum signal generator 220 is sent to the gate circuit 212. The signal is supplied to the switch 208 through the same, and is instructed to average the signals of the reflected light amount detection means 8. When the second output output from the command unit 52 is at the L level, the switching unit 208 is switched through the gate circuit 212, and the input signal of the averaging unit 12 is passed through and supplied to the focusing state detecting unit 51. In this way, when the amplitude of the tracking error signal becomes small due to defocusing or the like, a pulse having a short cycle is inserted in the first output pulse output from the tracking error maximum signal generator 220 due to noise, and the averaging means 12 Can be prevented from malfunctioning.

As described above, by using the averaging means 12 for averaging according to the reflected light amount signal when the tracking error signal is maximum, it is possible to realize with a simple circuit configuration without using a divider or the like.

In the first averaging means 9 described above, the averaging is performed for a time sufficiently longer than the rotation period. However, the averaging is performed according to the reflected light amount signal when the tracking error signal is maximum, and Alternatively, an averaging means for averaging may be used according to the maximum value of the reflected light amount signal in the range of the averaging time. In this case as well, the overall configuration of the optical disk device is the same as that shown in FIG.

FIG. 13 is a block diagram showing the structure of the fifth averaging means 13 having such a function. The same components as those of the averaging means described in FIGS. 9 to 12 are denoted by the same reference numerals, and detailed description thereof will be omitted. Here, the AD converter 20
The first storage device 241 and the second storage device 242 are provided in series after the third storage device 3, and the outputs of these storage devices are set to the maximum value output device 24.
3 and outputs the selected maximum value to the DA converter 207. The AD converter 203 converts the reflected light amount signal into a digital value in synchronization with the first output pulse of the tracking error maximum signal generator 220. And the first
The memory 241 of holds the digital value. The second memory 242 is the tracking error maximum signal generator 220.
The output of the first storage device 241 is held in synchronization with the first output pulse of the. The second memory 242 holds the digital value sampled one time before, and the first memory 241 holds the digital value currently sampled. Maximum value output device 24
3 compares the outputs of the first storage device 241 and the second storage device 242 and outputs the maximum value of the two outputs. DA
The converter 207 is a tracking error maximum signal generator 22.
The output of the maximum value output device 243 is DA converted in synchronization with the first output pulse of 0.

As described with reference to FIG. 5, the reflected light amount signal is at the level of the change center point Pc at the maximum point of the tracking error signal. Therefore, the DA converter 207 holds the level at the change center point Pc, and the average signal has a constant level Ph.
Becomes Since the averaging time is shorter in the averaging means 13 than in the first averaging means 9 which averages in the time of the rotation cycle of the optical disc 1, the focus control can reduce the time until the deviation is detected. Since no divider is used, the circuit can be simplified. In addition, since a plurality of storage devices are used to obtain the maximum sampled value of the reflected light amount, a stable output can be obtained even when the sampled value changes due to noise or the like.

Even if the tracking error signal is configured to hold the level of the reflected light amount signal at the minimum point, the level at the change center point Pc can be held as shown in FIG. By configuring to hold the level of the reflected light amount signal at both the maximum point and the minimum point of the tracking error signal, averaging can be performed in half the time, and focus control takes time to detect the deviation. Can be shortened. By configuring the level of the reflected light amount signal when the tracking error signal is at a point of 0, only the maximum point Pa of the reflected light amount can be averaged, and the average signal is Ph in FIG. It becomes the level shown by.

FIG. 14 is a characteristic diagram showing the relationship between the reflected light amount signal, the average signal, and the focus error signal with respect to the focus distance when the reflected light amount signal detected during defocusing is focused on the photodetector. This figure shows a case where the amount of reflected light that is diffracted and modulated by a track is larger than the middle of the maximum level and the minimum level. Even when the optical disk device is configured using the optical pickup having such characteristics, it is possible to detect whether the light is focused by comparing with a predetermined threshold value and correctly detect the focus control state.

When the amplitude of the tracking error signal is small, when the second output of the command unit 52 is at the H level, the second output pulse of the maximum tracking error signal generator 220 is sent to the switching unit 208 through the gate circuit 212. The signal is given and switched to instruct to average the signals of the reflected light amount detection means 8. When the second output output from the command unit 52 is at the L level, the switching unit 208 is switched through the gate circuit 212, and the input signal of the averaging unit 13 is passed through and supplied to the focusing state detecting unit 51. In this case,
When the amplitude of the tracking error signal is small due to defocusing or the like, it is possible to prevent the focusing state detection unit 51 from malfunctioning due to the insertion of a pulse having a short cycle in the first output pulse of the tracking error maximum signal generator 220 due to noise. be able to.

As described above, by averaging according to the reflected light amount signal when the tracking error signal is maximum, the averaging means can be realized with a simple circuit configuration without using a divider or the like. In addition, since the maximum of the digital values obtained by sampling the reflected light amount is output using a plurality of storage devices, a stable output can be obtained even when the sample value changes due to noise or the like. Further, by holding the level of the reflected light amount signal when the tracking error signal is at a point of 0, only the maximum point Pa of the reflected light amount can be averaged. Even if the reflected light amount signal detected at the time of defocus is larger than the middle of the maximum level and the minimum level of the reflected light amount diffracted and modulated by the track when focused on the photodetector, it is compared with a predetermined threshold value. Thus, it is possible to detect whether the light is focused and to correctly detect the focus control state.

In the averaging means 13 as described above, the time point at the point Pa at which the reflected light amount signal becomes maximum indirectly is obtained using the phase relationship between the tracking error signal and the reflected light amount signal. Alternatively, it may be directly obtained from the reflected light amount signal.

FIG. 15 is a block diagram showing the structure of the sixth averaging means 14 having such a function. The same parts as those of the averaging means shown in FIGS.
Detailed description is omitted. Here, the maximum reflected light amount detection means 250 is provided, and this output pulse is applied to the AD converter 203, the memory 221, and the DA converter 207. The maximum reflected light amount detecting means 250 in FIG. 15 compares the AC component of the reflected light amount signal with a reference voltage to generate a pulse signal when the reflected light amount becomes maximum. The reference voltage here is set lower than the maximum value of the reflected light amount signal modulated by the track diffraction. In this way, find the point where the direct reflected light amount signal becomes maximum,
The same effect as when the averaging means 12 of FIG. 12 is used can be obtained.

Further, the averaging means 14 obtains the time point at point Pa at which the reflected light amount signal becomes maximum from the tracking error signal and the reflected light amount signal, but the time at point Pb at which the reflected light amount signal becomes minimum than the reflected light amount signal. May be asked. In this case, since the level of the detected signal becomes low, the same effect can be obtained by passing the output of the DA converter 207 through the level shift circuit or the like.

Further, in the averaging means 14, the time point at which the reflected light amount signal becomes maximum is obtained from the tracking error signal and the reflected light amount signal, but the AC component signal of the reflected light amount signal becomes 0 from the reflected light amount signal. The time point at the point Pc may be obtained. In this case, the level of the detected signal is the averaging means 1
As in the case of using 2, the level becomes Ph. DA converter 2
The output of 07 is passed through a level shift circuit, etc., and the same effect as in the case of using the averaging means 12 can be obtained.

Although the averaging means described above is partially configured by a digital circuit, it may be configured by an analog circuit. It is a well-known and well-known technique that averaging can be realized by a low-pass filter, a peak hold circuit, and a sample hold circuit. Further, although the averaging means 9 to 14 and the focusing state detecting means 51 are partially configured by analog circuits, they may be configured by digital circuits. It is a well-known and well-known technique that switching an analog output value in accordance with a control signal is equivalent to replacing a digital value, and that level comparison can be realized by comparing digital values.

Although the SSD method is used as the focus error detection method and the push-pull method is used as the tracking error detection method in this embodiment, other detection methods may be used. In the present embodiment, the reflected light amount signal output from the reflected light amount signal detecting means 8 is directly averaged by the averaging means. However, the reflected light amount signal is amplified, attenuated, band-limited, or calculated with other signals. You may use it after doing. As a result, the influences of the optical power of the laser light, the offset voltage of the amplifier, the disturbance during the servo gain adjustment, and the like can be removed, and more stable detection can be performed.

In this embodiment, the average signal output from the averaging means is directly compared by the focusing state detecting means 11, but the reflected light amount signal is amplified, attenuated, band-limited, or compared with other signals. It may be used after calculation. As a result, influences of the optical power of the laser light, the offset voltage of the amplifier, the disturbance at the time of adjusting the servo gain, and the like can be removed, and more stable detection can be performed.

(Second Embodiment) An optical disk device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 16 is a block diagram showing the configuration of the optical disc device according to the second embodiment. The same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the first embodiment, the average signal output from the averaging means is directly compared by the focusing state detecting means 51, but in the present embodiment, as shown in FIG.
Is provided, and the output of the reference power supply 50 is set to the offset addition amplifier 6
The configuration is such that it can be changed by 0. The offset addition amplifier 60 adds an offset according to the second output of the command unit 52. When the tracking control is applied or the amplitude of the tracking error signal is small, the voltage of the reference voltage source 50 is output. When focus control is applied and tracking control is not applied, a voltage corresponding to the output of the averaging means 9 is output.

FIG. 17 is a characteristic diagram showing the relationship between the focus distance and each signal in the optical disk device shown in FIG. 17A is a characteristic diagram showing the relationship between the focus distance and the reflected light amount signal, FIG. 17B is a characteristic diagram showing the relationship between the focus distance and the average signal, and FIG. 17C is a diagram showing the focus distance and the focus error signal. It is a characteristic view which shows a relationship.

By the above-mentioned operation, the output of the offset addition amplifier 60 becomes a signal indicated by Vthv. The focus state detecting means 51 can correctly detect the defocus by comparing the output of the reflected light amount detecting means 8 with the output Vthv of the offset addition amplifying means 60.
Instead of the averaging means 9, any of the averaging means 10 to 14 described above may be used.

[0101]

As described above, according to the first to third aspects of the present invention, by providing the averaging means, the reflected light amount detected at the time of defocusing is focused on the photodetector. Even if the level is higher than the lowest level that is diffracted and modulated by the track when it is in motion, the modulation by the track is averaged, and it is detected whether the light is focused by comparing with a predetermined threshold, and the state of focus control is correctly detected. can do.

In particular, according to the invention described in claim 4, by providing an averaging means which does not perform averaging when tracking control is applied, focus control is deviated from the state where tracking control is applied. If
It is possible to detect that the focus control is out of control faster.

According to the invention described in claim 7, the averaging means configured to perform averaging in the time of one cycle of the tracking error is used.
Since the averaging time is shorter than the averaging in the rotation cycle of, the focus control can shorten the time until the deviation is detected.

According to the eighth aspect of the present invention, by using the averaging means configured to perform the averaging according to the reflected light amount signal when the tracking error signal is at 0, the tracking signal at 0 is obtained. Since the processing is performed only at the intersections, the AD converter can be used even if it has a long conversion time, and the calculation accuracy can be improved.

According to the ninth aspect of the invention, by using the averaging means configured to perform the averaging in accordance with the reflected light amount signal when the tracking error signal is at the maximum, the divider or the like is used. It can be realized with a simple circuit configuration that is not used.

According to the tenth aspect of the invention, by using the averaging means configured to perform the averaging according to the reflected light amount signal when the tracking error signal is at the maximum, the divider and the like are used. It can be realized with a simple circuit configuration that is not used.

According to the eleventh aspect of the present invention, since the maximum digital value of the reflected light quantities sampled is output, a stable output can be obtained even when the sample value changes due to noise or the like. it can. By configuring the level of the reflected light amount signal when the tracking error signal is at a point of 0, only the maximum point of the reflected light amount can be averaged, and the reflected light amount signal detected during defocusing can be averaged. Is larger than the middle of the maximum level and the minimum level of the reflected light that is diffracted and modulated by the track when it is focused on the photodetector, whether the light is focused by comparing with the predetermined threshold value. Can be detected, and the focus control state can be correctly detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an optical disc device according to a first embodiment of the present invention.

FIG. 2A is a perspective view showing a reflected light path from an optical disk and an integrated body, and FIG. 2B is a side view of the reflected light path and the integrated body.

FIG. 3 is a layout diagram showing types and areas of diffraction patterns on a hologram used in the optical disc device of the present embodiment.

FIG. 4 is a plan view showing a configuration of a photodetector used in the optical disc device of the present embodiment.

FIG. 5 (a) shows an optical disk device of the present embodiment.
Is a characteristic diagram showing a time change of a reflected light amount signal, FIG. 9B is a characteristic diagram of an average signal, and FIG. 9C is a characteristic diagram showing a time change of a tracking error signal.

FIG. 6 is a side view showing a relationship between a reflected optical path and an integrated body when a light beam is defocused in the optical disc device of the present embodiment.

FIG. 7 is a plan view showing a light spot distribution when a light beam is defocused in the photodetector of the present embodiment.

FIG. 8 (a) shows an optical disc device according to the present embodiment.
Is a characteristic diagram showing the relationship between the focus distance and the reflected light amount signal,
(B) is a characteristic diagram showing the relationship between the focus distance and the average signal, and (c) is a characteristic diagram showing the relationship between the focus distance and the focus error signal.

FIG. 9 is a block diagram showing a configuration of a first averaging means in the optical disc device of the present embodiment.

FIG. 10 is a block diagram showing a configuration of a second averaging means in the optical disc device of the present embodiment.

FIG. 11 is a block diagram showing a configuration of a third averaging means in the optical disc device of the present embodiment.

FIG. 12 is a block diagram showing a configuration of a fourth averaging means in the optical disc device of the present embodiment.

FIG. 13 is a block diagram showing the configuration of fifth averaging means in the optical disc device of the present embodiment.

FIG. 14 is a graph showing a difference between a maximum level and a minimum level of a reflected light amount diffracted and modulated by a track when a reflected light amount signal detected at the time of defocusing is focused on a photodetector in the optical disc device of the present embodiment. FIG. 7 is a signal level diagram in the case where is also large. (A) is a characteristic diagram showing the relationship between the focus distance and the reflected light amount signal, (b) is a characteristic diagram showing the relationship between the focus distance and the average signal, and (c) is a characteristic diagram showing the relationship between the focus distance and the focus error signal. is there.

FIG. 15 is a block diagram showing a configuration of sixth averaging means in the optical disc device of the present embodiment.

FIG. 16 is a block diagram showing an overall configuration of an optical disc device according to a second embodiment of the present invention.

FIG. 17 shows an optical disk device according to a second embodiment,
(A) is a characteristic diagram showing the relationship between the focus distance and the reflected light amount signal, (b) is a characteristic diagram showing the relationship between the focus distance and the average signal, and (c) is a characteristic diagram showing the relationship between the focus distance and the focus error signal. is there.

[Explanation of symbols]

 1 Optical Disc 2 Rotating Means 5 Focus Error Signal Detecting Means 6 Focus Control Means 7 Focus Actuator Driver 8 Reflected Light Amount Signal Detecting Means 9-14 Averaging Means 50 Reference Power Source 51 Focusing State Detecting Means 52 Commander 53 Tracking State Detecting Means 60 Offset Addition Amplifier 100 Optical pickup 101 Integrated body 102 Photodetector 103 Hologram 104 Prism 105 Focusing lens 107 Focus actuator 108 Tracking actuator 121 Laser light source 122 Mirror 131-139 Photodetector 150-153 I / V converter 201 First oscillator 202 No. 2 Oscillator 203 AD converter 204 Summing memory 205 Counter 206 Divider 207 DA converter 208 Switcher 210 Track crossing signal generation 212, 232 the gate circuit 230 tracking error zero crossing signal generator 220 a tracking error up signal generator 221 stores 241 the first storage unit 242 second storage unit 243 maximum value output 250 reflected light amount maximum detection means

Claims (13)

[Claims] 1. An optical disk is rotated by a rotating means,
When recording or reproducing information via an optical pickup,
An optical disk device for controlling a posture of a focusing lens of the optical pickup to perform tracking control so that a laser beam follows a track of the optical disk, and performing focusing control so that the laser beam focuses on a desired spot. A photodetector that irradiates a recording surface of an optical disc with a laser beam and receives the reflected light, and a focus signal output from the photodetector when the spot of the laser beam is scanned along the track direction of the optical disc. A reflected light amount signal detecting means for generating a reflected light amount signal of a track from the track, an averaging means for averaging the reflected light amount signals output by the reflected light amount signal detecting means, and outputting an average signal; and the averaging means. The reflected light from the recording surface of the optical disc is Focusing state detecting means for detecting whether or not focusing is performed on the light receiving surface of the light detecting device, and whether or not focus control is performed again based on the detection result of the focusing state detecting means, and the focusing state For example, an optical disk device comprising: an instruction unit for instructing recording or reproduction of information on a track of the optical disk. 2. An optical disk is rotated by a rotating means,
When recording or reproducing information via an optical pickup,
An optical disk device for controlling a posture of a focusing lens of the optical pickup to perform tracking control so that a laser beam follows a track of the optical disk, and performing focusing control so that the laser beam focuses on a desired spot. A hologram plate for irradiating a recording surface of the optical disc with a laser beam and diffracting the reflected light into at least 0th order light and ± 1st order light; and a first photodetector for detecting 0th order light diffracted by the hologram plate, A second photodetector for detecting + 1st order light, and -1
A photodetector including a third photodetector for detecting the next light, and an output of the second or third photodetector when the spot of the laser beam is scanned along the track direction of the optical disc. A reflected light amount signal detecting means for generating a reflected light amount signal of a track from a plurality of focus signals; and an averaging means for averaging the reflected light amount signals output by the reflected light amount signal detecting means at a predetermined time, and outputting an average signal, Focusing state detecting means for detecting whether or not the reflected light from the recording surface of the optical disc is focused on the light receiving surface of the photodetector by comparing the average signal output from the averaging means with a predetermined threshold value. Based on the detection result of the focusing state detecting means, it is determined whether or not focus control is performed again. An optical disk device comprising: a command unit for instructing recording or reproduction. 3. An optical disk is rotated by a rotating means,
When recording or reproducing information via an optical pickup,
An optical disk device for controlling a posture of a focusing lens of the optical pickup to perform tracking control so that a laser beam follows a track of the optical disk, and performing focusing control so that the laser beam focuses on a desired spot. A hologram plate for irradiating a recording surface of the optical disc with a laser beam and diffracting the reflected light into at least 0th order light and ± 1st order light; and a first photodetector for detecting 0th order light diffracted by the hologram plate, A second photodetector for detecting + 1st order light, and -1
A photodetector including a third photodetector for detecting the next light, and an output of the second or third photodetector when the spot of the laser beam is scanned along the track direction of the optical disc. A reflected light amount signal detecting means for generating a reflected light amount signal of a track from a plurality of focus signals; and an averaging means for averaging the reflected light amount signals output by the reflected light amount signal detecting means at a predetermined time, and outputting an average signal, Focusing state detecting means for detecting whether or not the reflected light from the recording surface of the optical disc is focused on the light receiving surface of the photodetector by comparing the average signal output from the averaging means with a predetermined threshold value. According to the reflected light amount signal of the reflected light amount signal detection means, when it is determined that the laser beam is in focus,
Offset addition amplification means for changing the threshold voltage applied to the focus state detection means, and whether or not focus control is performed again based on the detection result of the focus state detection means, and if it is in focus state An optical disk device, comprising: a command unit for instructing recording or reproduction of information on a track. 4. The command means cancels the averaging process when tracking control is applied, gives the signal of the reflected light amount signal detection means to the focusing state detection means, and averages when tracking control is not applied. 4. The optical disk device according to claim 1, wherein the averaging means is instructed to perform an averaging process and give the averaged value to the focusing state detecting means. 5. The photodetector according to claim 1, wherein the first photodetector reads out information recorded on the track, the second photodetector outputs a focus signal, and the third photodetector. 4. The optical disk device according to claim 2, wherein the detector outputs a tracking signal. 6. The optical disc apparatus according to claim 1, wherein the averaging unit averages the reflected light amount signal for a period equal to or longer than the rotation period of the optical disc. 7. The averaging means sets the time for averaging the reflected light amount signal to be one cycle of a tracking error signal obtained from the second or third photodetector. 5. The optical disk device according to any one of items 4 to 4. 8. The averaging means averages the reflected light amount signal at the time when the tracking error signal obtained from the second or third photodetector is at or near 0. The optical disk device according to any one of claims 1 to 4, wherein: 9. The averaging means averages a reflected light amount signal at a point at or near a point where the tracking error signal obtained from the second or third photodetector becomes maximum. The optical disk device according to any one of claims 1 to 4, wherein 10. The averaging means averages a reflected light amount signal at a point at or near a point where the tracking error signal obtained from the second or third photodetector becomes minimum. The optical disk device according to any one of claims 1 to 4, wherein 11. The averaging means averages the maximum value of the reflected light amount signal obtained from the reflected light amount signal detecting means and a value in the vicinity thereof, according to any one of claims 1 to 4. 2. An optical disk device according to item 1. 12. The averaging means averages the minimum value of the reflected light amount signal obtained from the reflected light amount signal detecting means and a value in the vicinity thereof. 4. The optical disc device according to any one of 4 above. 13. The averaging means averages the reflected light amount signal at a time point at or near 0 of the AC component of the reflected light amount signal obtained from the reflected light amount signal detecting means. The optical disk device according to claim 1.