JPH09326126A - Information recording medium reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform rapid and precise inter-layer jump of an optical pickup in a reproducing device of a multi-layer DVD disk. SOLUTION: A timer T1 is operated for recognizing arrival of a lens to an upper limit position (step S4), and the lens is raised up (step S5), and when a signal exceeding a threshold value TH among focus error signals detected in a rise process is detected (step S6; YES), the timer T2 is operated (step S7), and a time until a next peak value exceeds the threshold value TH is measured (steps S8, S9). When the value of the T1 exceeds t1, and the lens arrives at the upper limit position (step S10; YES), the T1 and the lens operation are stopped (steps S11, S12), and an inter-layer interval is obtained based on the value of the T2 (step S13), and at least one among pulse width, pulse height value, brake time and gain-up time of the most suitable focus jump is selected based on the inter-layer interval to be stored in a RAM (step S14).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium such as an optical disc in which information is magnetically recorded by phase pits or the like, the information recording medium having a multi-layer or single-layer information recording layer. The present invention relates to a technical field of a reproducing device that reproduces the information.

[0002]

2. Description of the Related Art In recent years, a DVD (Digital Video Disk or Digital Vede), which is a high-density recording medium capable of recording a movie or the like, with a dramatically improved storage capacity as compared with a conventional CD.
rsatile disk) is being actively developed. This DV
To reproduce D, an optical pickup for converging a light beam is provided at the focal position of the information recording layer of the recording medium, and the objective lens of the optical pickup and the distance between the information recording layer are kept constant by focus servo control. A device that stably reads information is used.

In this focus servo control, since the area where the servo error signal can be detected is narrow, the servo loop is opened before the focus servo control, and the objective lens is placed in the direction perpendicular to the information recording layer. A so-called focus search operation is required, in which the servo loop is closed by moving a predetermined amount and seeing the zero cross of the focus error signal (S-shaped signal) output at that time.

[0004]

However, recently, a multilayer disc capable of recording more information has been developed by constructing the information recording layers of DVD in multiple layers, and the reproduction of such a multilayer disc. In order to perform the step from one side, it is necessary to perform the focus search operation for each layer.

That is, in such a multi-layer disc reproducing apparatus, it is necessary to jump the objective lens of the optical pickup to an appropriate position each time the information recording layer to be reproduced is switched. Since each disc is different within the disc standard, the jump amount cannot be set uniquely, and the focus search operation is performed for each disc and for each layer to set the reference position for the focus servo. Had to set.

Therefore, in the conventional apparatus for performing the focus search operation, it is necessary to detect the zero-cross of the focus error signal every time the information recording layer is switched, and the information recording layer in the multi-layer DVD can be switched quickly. It was difficult.

Therefore, the present invention has been made in view of the above problems, and is a DVD in which information recording layers are formed in multiple layers.
It is an object of the present invention to perform a quick reproducing operation at the time of switching recording layers in the reproducing apparatus.

[0008]

In order to solve the above-mentioned problems, a reproducing apparatus for an information recording medium according to a first aspect of the present invention is an information recording medium having a single-layer or multi-layer information recording layer on which information is recorded. A reproducing apparatus of, which includes an objective lens,
A reading unit that reads information recorded on the information recording layer by irradiating the information recording layer with a light beam from the information recording medium and receiving reflected light thereof,
Direction for moving the objective lens toward or away from the information recording medium by receiving a control signal in order to change the relative distance between the objective lens of the reading means and the information recording surface parallel to the optical axis. A moving means for moving to, an error signal generating means for generating a focus error signal corresponding to the read signal based on the read signal by the reading means, and a time measuring means for measuring an interval at which the focus error signal appears, When a plurality of the focus error signals exceeding a predetermined reference value appear during the movement period of the objective lens by the moving means in any one direction, information recording is performed based on the time measurement result of the time measuring means. A calculation means for calculating an interlayer distance between the layers and a pre-operation for the interlayer movement of the objective lens by the moving means. A selection storage means for selecting and storing a parameter from the parameters of the defined control signals corresponding to the interlayer spacing obtained by said arithmetic means,
By the parameters stored by the selection storage means,
Control means for outputting the control signal to move the objective lens by the moving means.

According to the reproducing apparatus of the information recording medium of the first aspect, the moving means moves the objective lens of the reading means toward or away from the information recording medium to record the information of the light beam of the reading means. When passing the focus position with respect to the layer, a focus error signal is generated by the error signal generating means based on the read signal at the time of passing. When a plurality of focus error signals exceeding the predetermined reference value among the focus error signals appear during the movement period of the reading unit by the moving unit in one of the approaching direction and the separating direction. In the above, the interlayer distance of the information recording layer is calculated based on the appearance interval result of each focus error signal timed by the time measuring means. That is, a plurality of focus error signals exceeding the reference value can be obtained during the movement period of the moving means in any one of the directions because the information recording layers of the information recording medium are formed in multiple layers. The inter-layer spacing of each information recording layer is obtained from the relationship between the predetermined moving speed of the moving means and the time measurement result of the time measuring means. Therefore, by selecting and storing a parameter corresponding to the obtained interlayer distance from the parameters of the control signal for the moving means which is predetermined for moving the desired interlayer distance by the selection storing means, Thereafter, when reading information of a plurality of information recording layers, if a control signal is output to the moving means based on the stored parameters by the control means, the objective lens of the desired information recording layer can be controlled. The move is done.

An information recording medium reproducing apparatus according to a second aspect of the present invention is the information recording medium reproducing apparatus according to the first aspect, wherein the moving means is means for moving the reading means by applying a pulse signal. The parameter of the control signal is at least one of a pulse width, a peak value, a braking time, and a gain-up time.

According to the reproducing apparatus of the information recording medium of the second aspect, the reading means is moved by a predetermined distance by applying a pulse signal to the moving means.
The moving distance and the stability are determined by the parameters of the control signal, such as pulse width, peak value, braking time, and gain-up time. Therefore, by storing at least one of these parameters and outputting the control signal to the moving means using the stored parameter, only the desired moving distance, that is, the desired information recording layer It is moved to the reading position.

A reproducing apparatus for an information recording medium according to a third aspect of the present invention is the reproducing apparatus for an information recording medium according to the first or second aspect, which appears during a reciprocating movement period of the reading means by the moving means. It is characterized by further comprising a discriminating means for discriminating the kind of the information recording medium on the basis of the time measurement result of the time measuring means for the focus error signal which is a focus error signal exceeding the predetermined reference value.

According to the information recording medium reproducing apparatus of the third aspect, for example, when the reading means is moved in the direction of approaching the information recording medium, the focus which first exceeds the predetermined reference value from the time when the movement is started. The time until the error signal is obtained is shorter as the distance from the surface of the information recording medium to the information recording layer is shorter, and the time is longer as the distance is larger, and the information recording medium having a plurality of information recording layers is formed. In, a plurality of continuous focus error signals are obtained. On the other hand, when the reading means reaches the upper limit position and is then moved in a direction of separating from the information recording medium, a focus error signal exceeding a predetermined reference value is first obtained from the time when the movement is started. The shorter the time is, the larger the distance from the surface of the information recording medium to the information recording layer, the longer the time,
Further, in the information recording medium in which the information recording layers are formed in multiple layers, a plurality of continuous focus error signals can be obtained. Therefore, the adjoining intervals of the focus error signals become shorter as the distance from the surface of the information recording medium to the information recording layer becomes larger, when the reading means is moved in the order as described above. Is smaller, the length is longer, and is the shortest in the case of multiple layers. Further, when the moving order of the reading means is reversed, the opposite relationship is obtained. In this way, the information recording medium is discriminated based on the appearance interval of the focus error signal by the time measuring means. Then, when it is determined that the information recording medium is further formed in multiple layers, the calculation of the interlayer spacing as described in claim 1 or claim 2 and the control signal based on the calculation result Parameters are selected and stored.

An information recording medium reproducing apparatus according to a fourth aspect of the present invention is the information recording medium reproducing apparatus according to any one of the first to third aspects, wherein the error signal generating means includes the received light signal. Is also a means for generating a tracking error signal based on the above, and calculates the focus gain value and / or the tracking gain value of each layer based on the focus error signal and / or the tracking error signal generated by the error signal generating means. Servo calculation means, storage means for storing the focus gain value and / or tracking gain value obtained by the calculation, and the focus gain value and / or stored in the storage means.
Alternatively, a servo control unit that performs focus servo control and / or tracking servo control based on the tracking gain value is provided.

According to the reproducing apparatus of the information recording medium of the fourth aspect, for example, the focus gain value is calculated and stored by reading a plurality of peak-to-peak values of the focus error signal and obtaining the average, and The tracking gain value is calculated and stored by reading a plurality of peak-to-peak signals of the tracking error signal and calculating an average. When the plurality of focus error signals are read, the tracking gain value is read.
The calculation of the interlayer spacing of the information recording layers of the information recording medium formed in multiple layers such as the reproducing apparatus for the information recording medium described in any one of 1, and the selection and storage of the parameter of the control signal are performed. Therefore, when reading information from a plurality of information recording layers, the parameters stored as described above are used to move to a desired information recording layer, and further, the focus gain value recorded as described above is used. as well as/
Alternatively, focus servo control and / or tracking servo control is performed according to the tracking gain value.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. Although the apparatus of the present embodiment is a DVD / CD (Compact Disk) compatible reproducing apparatus, the case of reproducing a DVD as an information recording medium will be described in the description of the present embodiment.

FIG. 1 is a block diagram showing a schematic structure of the reproducing apparatus of the present embodiment. In FIG. 1, reference numeral 1 is an optical disc 1 which is a DVD as an information recording medium. On the optical disc 1, information is recorded on an information track by, for example, phase pits or magnetic recording marks, and a light beam is emitted from a laser diode (not shown) included in the optical pickup 2 serving as a reading unit. Is formed.

The reflected light of this light spot is incident on a light receiving element such as a photodetector (not shown), which is included in the optical pickup 2 and is divided into four parts, as reflected light having astigmatism, and a detection signal is output from the light receiving element. Is output.

RF amplifier 3 as error signal generating means
Generates an RF (Radio Frequency) signal from the detection signal output from the light receiving element of the optical pickup 2, and outputs a focus error signal FE and a tracking error signal TE.

This RF signal is demodulated and corrected by the demodulation / correction circuit 4, and is input to the spindle driver 5 as a reference signal for synchronizing the spindle motor 6, and at the same time, the video circuit 7 and the audio circuit 8 are also provided. Are input as a video signal and an audio signal, respectively, and a video output and an audio output are respectively obtained.

On the other hand, the focus error signal FE and the tracking error signal TE are sent to the CPU 9 as a control means.
Are output as a focus drive signal FD and a tracking drive signal TD to a focus driver 11 and a tracking driver 12 as moving means, respectively, thereby performing focus servo and tracking servo. The servo operation by this servo circuit 10 is C
The closed state and the open state are switched by the servo control signal FSON from the PU 9. Further, the gain up signal GUP for increasing the sensitivity of the servo is also sent to the CPU 9
Is output to the servo circuit 10. The focus drive signal FD and the tracking drive signal TD are output under the control of the servo circuit 10 when the servo is in the closed state, and when the servo is in the open state, the focus jump signal and the focus are raised by the output command from the CPU 9. , A falling signal is output. Therefore, the RAM 9 that stores the pulse width and the like of the focus drive signal FD in the CPU 9
3 is connected.

An operation panel 14 is connected to the CPU 9 so that operation information such as start and stop of reproduction of the optical disk 1 can be input. Although not shown in FIG. 1, a signal indicating whether or not the optical disc 1 is loaded is also input to the CPU 9 via a sensor or the like.

In the reproducing apparatus of this embodiment as described above, in order to reproduce a multi-layer optical disc, it is necessary to jump the objective lens of the optical pickup 2 from one information recording layer to another information recording layer. The jump is performed by outputting the kick pulse as shown in FIG. 2 to the focus driver 11 as the focus drive signal FD. The kick pulse height (crest value) and pulse width are set in consideration of the interlayer distance of the information recording layer and the amount of movement of the objective lens. For example, by increasing the crest value and shortening the pulse width, You can jump to the target position faster.

When the kick pulse is output, the CPU 9
The servo drive signal FSON is output from the servo circuit 10 to open the servo, and the focus drive signal FD is output so that the kick pulse is output to the servo circuit 10 with a predetermined pulse width and peak value. Issue an output request for. As a result, the servo circuit 10
Then, a kick pulse as shown in FIG. 2 is output to the focus driver 11, and the objective lens of the optical pickup 2 jumps by a predetermined amount according to the drive signal based on the kick pulse from the focus driver 11. If this jump is, for example, a jump from the bottom to the top, the kick pulse moves to a position higher than the in-focus point, so that an upward focus error signal FE is obtained, and the in-focus point of the second layer is obtained. As a result, the downward focus error signal FE is obtained, so that the focus is closed when the downward focus error signal FE is obtained. Therefore, the CPU 9 detects the zero-cross of the focus error signal FE to bring the servo control signal FSON into the closed state.
To the servo circuit 10, and further, in order to stabilize the focus coil at the jumped point, a gain up signal GUP for temporarily increasing the focus gain.
Is output to the servo circuit 10. This gain up signal G
The output time of UP is called gain up time.

In order to suddenly stop the optical pickup at the jumped point, a brake pulse may be given to the focus driver 11 as a focus drive signal FD after the jump pulse as shown in FIG. Also in this case, the focus coil could not stabilize immediately because it tried to suddenly stop the moving object, so not only the brake pulse was applied, but the focus gain was temporarily increased until it became stable. The method is done.

As described above, in order to make the optical pickup jump for reproducing a multi-layer disc, the pulse width,
It is necessary to set the peak value, brake pulse width, and gain-up time to the specified values, but if the interlayer spacing of the information recording layer is unknown, average pulse width, peak value, brake pulse width, gain-up Since it is necessary to set the time and output the kick pulse to detect the zero-cross signal of the focus error signal FE, if these values are not appropriate, for example, if the interlayer distance is larger than the average, the servo is closed. It sometimes took an extra time to reach the state.

However, if the relationship between the amount of movement of the objective lens and the pulse width, peak value, brake pulse width, and gain-up time is investigated in advance, an appropriate pulse width or the like is selected according to the interlayer spacing. This allows the objective lens to jump in the shortest time.

Therefore, in the present embodiment, the pulse width, the peak value, the brake pulse width, and the gain-up time corresponding to some interlayer intervals are stored in advance, and the information recording layer is immediately after mounting the optical disc. By measuring the inter-layer spacing and reading and using the pulse width or the like corresponding to the inter-layer spacing when switching the information recording layers, the objective lens of the optical pickup 2 can be jumped to the target position faster and more accurately. I did it.

In the present embodiment, the pulse width, the peak value, the brake pulse width, and the gain-up time corresponding to the interlayer distance are measured in advance and stored in a ROM (not shown) in the CPU 9 as a table, and the table is stored. At times, a pulse width or the like corresponding to the interlayer interval is selected from the table and stored in the RAM 13. That is, in this embodiment, the CPU 9 and the RAM 13 are used as the selection storage means.

Next, the method for measuring the interlayer distance in this embodiment will be described. First, the optical pickup 2 used in the apparatus of this embodiment will be described in detail. The optical pickup 2 of the present embodiment includes, for example, a bifocal lens, as shown in FIG.

The optical pickup 2 provided with this bifocal lens has a structure capable of irradiating two light beams which focus at different positions on the same straight line. That is, in the bifocal lens, as shown in FIG. 4, the diffraction grating H and the objective lens R are arranged on the same optical path. And split into three beams of ± 1st order light,
Among them, the difference between the optical path lengths of the 0th order light and the + 1st order light is used to focus the 0th order light and the + 1st order light at different positions on the same straight line.

More specifically, the + 1st order light is configured to focus on a position farther from the objective lens R than the 0th order light, and the 0th order light is optimally collected on the information recording surface of the DVD. The optical pickup is set so that the + 1st-order light is optimally condensed on the information recording surface of the CD as well as the light is emitted. By using the optical pickup equipped with such a bifocal lens, the apparatus of the present embodiment Both DVD and DVD can be played back.

The two light beams from the optical pickup 2 having the bifocal lens are set so that the + 1st order light is optimally condensed by the CD and the 0th order light is optimally condensed by the DVD. Therefore, the focal length of + 1st order light is longer. Therefore, for example, as shown in FIG.
When the bifocal lens is raised with respect to VD, first +1
The next light is focused on the first layer of the information recording surface of the DVD to detect a focus error signal, and then focused on the second layer of the information recording surface to detect a similar focus error signal. Next, a pseudo focus error signal generated when the reflected light of the + 1st order light from the first layer follows the optical path of the 0th order light is detected, and the reflected light from the second layer similarly simulates the pseudo focus error signal. Focus error signal is detected. Finally, the focus error signal from the first layer corresponding to the 0th order light is detected, and further the focus error signal from the second layer is detected.

As described above, in the multi-layer disc, by using the optical pickup 2 having the bifocal lens, a total of 6 focus error signals are generated. When the threshold TH that is larger than the peak value of the signal and smaller than the peak value of the focus error signal for the 0th order light is set, the focus error signal that exceeds the threshold TH is only the focus error signal for the 0th order light. Therefore,
Since the moving speed of the optical pickup is constant, the interval between the first layer and the second layer of the information recording layer can be measured by measuring the appearance interval of the two focus error signals with respect to the 0th order light.

That is, when a focus error signal larger than the threshold value TH is detected, a timer as a time measuring means is operated, and when the next focus error signal is detected, the timer is stopped to continuously perform the operation. The distance between the two focus error signals can be obtained. Assuming that the value obtained by the measurement of this timer is t and the constant based on the up and down speeds of the objective lens is a, X = t / a is a value unique to the layer interval, and is calculated by the CPU 9 as the calculating means. , For example, if X is 1.6 ≦ X ≦ 2.5 (1), it is determined that the interlayer distance is 40 μm, and X is 2.6 ≦ X ≦ 3.5 (2). Then, if it is determined that the inter-layer spacing is 60 μm, if t = 4 msec and a = 2, then X = 4 msec / 2 = 2 and it is determined that the discs have a spacing of 40 μm.

Regarding the measurement interval of the focus error signal, as shown in FIG. 5A, from the time when the focus error signal exceeds a predetermined threshold value TH to the time when the next focus error signal exceeds the threshold value TH. Alternatively, as shown in FIG. 5 (B), the threshold value may be set up and down, and the second focus error may start from the time when the upper threshold value is exceeded due to the rising of the first focus error signal. It may be an interval until the time when the signal falls below the lower threshold value due to the falling of the signal.

Next, the operation of the apparatus of this embodiment will be described with reference to FIGS. The respective processes shown in FIG. 6 are mainly performed by the CPU 9. Further, timers T1 and T2, which will be described later, are built in the CPU 9.

As shown in FIG. 6, first, it is determined whether or not a disc is set (step S1). When it is determined that the disc is set, the contents of the RAM 13 and the timers T1 and T2 are cleared, The registers and the like included in the CPU 9 are initialized (step S2). Next, the objective lens is moved down to the lower limit position shown in FIG. 4 (step S3), and after the objective lens reaches the lower limit position, the operation of the timer T1 for confirming that the objective lens reaches the upper limit position. Is started (step S4) and the objective lens is raised (step S5). Then, with respect to the focus error signal (see FIG. 4) detected in the ascending process, it is determined whether or not any of the peak values exceeds the threshold value TH (step S6), and the peak value has the threshold value TH.
When it exceeds (step S6; YES), the operation of the timer T2 is started to measure the time until the next peak value exceeds the threshold value TH (step S7). next,
It is determined whether or not the next peak value exceeds the threshold TH (step S8), and if it exceeds (step S8; YE).
S) and terminate the operation of the timer T2 (step S
9).

After that, the process waits until the value of the timer T1 exceeds the predetermined value t1 (step S10), and if it exceeds (step S10; YES), it is determined that the objective lens has reached the upper limit position, and the timer T1 is reached. Is stopped (step S11), and the raising operation of the objective lens is stopped (step S12).

Then, based on the value of the timer T2, the inter-layer spacing of the information recording layer is obtained from the above-mentioned judgment formulas (1) and (2) (step S13), and based on the inter-layer spacing, the optimum value is obtained from the table. At least one of the pulse width, peak value, braking time, and gain-up time of the kick pulse is selected and stored in the RAM 13 (step S1).
4).

By storing the value for jumping the objective lens in this way, and thereafter, unless the disk is replaced, a control signal is output to the servo circuit 10 based on the stored value so that the objective The lens can be accurately and quickly jumped to an appropriate position for each information recording layer.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 7 and 8. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, discs are discriminated at the same time when the above-mentioned interlayer spacing is measured. For example, a single-layer DVD, a multi-layer DVD, or a disc is loaded. It also discriminates whether it is true or not. Therefore, in this embodiment, the CPU 9 functions as a discriminating means.

The hardware configuration of the apparatus of this embodiment is as follows.
Since it is similar to the above-described first embodiment, description thereof will be omitted, and the control in this embodiment will be described below based on FIGS. 7 and 8.

As shown in FIG. 7, first, it is determined whether or not a disc is set (step S20). When it is determined that the disc is set, the contents of the RAM 13 are cleared and a register included in the CPU 9 is set. For example, initialization such as clearing the register D and the counter E described below is performed (step S21). Next, the objective lens is moved down to the lower limit position shown in FIG. 8 (step S22), and after the objective lens reaches the lower limit position, the operation of the timer T1 for confirming that the objective lens reaches the upper limit position. Is started (step S23), and the objective lens is raised (step S24). Then, with respect to the focus error signal (see FIG. 8) detected in the ascending process, one of the peak values is the threshold TH1 (see
It is determined whether or not the value exceeds the reference numeral TH1 (step S).
25), if the peak value exceeds the threshold value TH1 (step S25; YES), the operation of the timers T2 and T4 is started (step S26).

This timer T2 is used to measure the interlayer spacing when the mounted disc is a multi-layer DVD, as in the first embodiment, and the timer T4 is used for a single-layer DVD. It is used to distinguish from a CD.

Next, it is judged whether or not the next peak value exceeds the threshold value TH1 (step S27), and the timer T1.
Before reaching the predetermined value t1, that is, when the objective lens has not reached the upper limit position (step S28; NO), when the threshold value TH1 is exceeded (step S27; YES), as shown in FIG. Since it can be determined that this is the case, the operation of the timer T2 is ended (step S29), and the process waits until the value of the timer T1 exceeds the predetermined value t1 (step S30), as in the first embodiment.

On the other hand, when the peak does not exceed the threshold value TH1 even when the timer T1 reaches the predetermined value t1 (step S27; NO to step S28; YES), as shown in FIG. 8, a single layer DVD or CD. Since it can be determined that this is the case, the value of the timer T2 is cleared (step S
31).

As described above, the timer T1 is set to the predetermined value t.
When it reaches 1, it is determined that the objective lens has reached the upper limit position, the operation of the timer T1 is terminated, and at the same time, in order to confirm that the lower limit position of the objective lens is reached, the timer T
The operation of 3 is started (step S32), and the descent of the objective lens is started (step S33).

Then, it is judged again whether or not the peak value exceeds the threshold value TH1 (step S34), and if it exceeds the threshold value TH1 (step S34; YES), the timer T
The operation of No. 4 is ended (step S35). As shown in FIG. 8, the interval t41 at which the FE peak value occurs when the disc is a single-layer DVD is shorter than the interval t42 at which the FE peak value occurs when the disc is a CD.

Next, the process waits until the timer T3 reaches the predetermined value t3 (step S36), and when it is determined that the timer T3 reaches the predetermined value t3 and the lens reaches the lower limit position (step S36; YES). Then, the operation of the timer T3 is ended (step S37), and the content of the timer T2 is judged in order to judge whether it is a multi-layer disc or a single-layer disc (step S38).

As described above, when the disc is a single layer, the content of the timer T2 is cleared, and therefore it is determined whether or not the content of the timer T2 exceeds 0 (step S38). It is possible to judge whether it is a single layer or a multilayer. That is, when the content of the timer T2 exceeds 0 (step S38; YES), it is determined that the DVD is a multi-layer DVD as in the first embodiment, and the first
In the same manner as in the first embodiment, the interlayer distance is obtained from the above-described determination formulas (1) and (2) based on the value of the timer T2 (step S39), and the optimum focus jump from the table is performed based on the interlayer distance. Pulse width, peak value,
At least one of the braking time and the gain-up time is selected and stored in the RAM 13 (step S40).

On the other hand, when the content of the timer T2 is 0 (step S38; NO), it is determined that the disc is a single layer disc, but it is necessary to determine whether it is a DVD or a CD. It is determined whether the value of T4 is a predetermined value t4 or more (step S41). This predetermined value t4
Is set to an intermediate value between the peak value interval for DVD and the peak value interval for CD, as shown in FIG.
DVD if the value is t4 or more, and CD if it is less than t4
Can be determined.

Therefore, if t4 or more (step S4
1; NO), it is determined to be a DVD, 2 is set in the register D (step S42), and the DVD focus gain, tracking gain, and equalizer are set (step S43). However, if it is less than t4 (step S41; YES), it is determined to be CD, 1 is set in the register D (step S44), and DV is set.
The focus gain, tracking gain, and equalizer for D are set (step S45).

Since all the discs have been discriminated at this point, next, in order to close the focus servo,
The objective lens is raised again (step S46), and the number of times the peak value exceeds the threshold value TH2 is counted to determine whether it is the 0th-order light or the + 1st-order light.
The focus is locked with the next light, or with the + 1st light for a CD. That is, by setting this threshold value TH2 to a value smaller than the peak value of the focus error signal for the + 1st order light of the DVD as shown in FIG. 8, as shown in FIG. The focus is closed when the peak value of the focus error signal due to the next light exceeds the threshold value TH2, exceeds the threshold value TH2 for the fifth time in the case of a multilayer DVD, and exceeds the threshold value TH2 for the first time in the case of a CD.

Immediately after raising the objective lens, it is determined whether or not the value of the register D is 0 in order to initialize the values of the register and the counter (step S47).
If D is 0 (step S47; YES), it is determined that the input to the register D is not made and the disc is a multi-layer disc. Therefore, the value of the counter E is set to 0 and the value of the register b is changed. It is set to 5 (step S48). On the other hand, if the register D is not 0 (step S47; N
O), since it can be determined that the case is a single-layer DVD or a CD as described above, the value of the counter E is set to 0 and the value of the register b is set to 3 (step S49).

Then, it is determined whether or not the peak value exceeds the threshold value TH2 (step S50), and if it exceeds the threshold value TH2 (step S50; YES), the counter E is incremented (step S51). Next, the register D is judged (step S52), and the register D becomes 1
If so, it is a CD, and the focus servo is closed when the focus error signal for the + 1st order light is obtained, and therefore this counting process is exited (step S52;
Yes). However, when the register D is 0 or 2, the DVD is a DVD and it is necessary to close the focus when the focus error signal for the 0th-order light is obtained. Therefore, the value of the counter E is set as described above. The counter E is repeatedly counted until the value of b is reached (step S52; NO-step S53; N).
O).

As described above, the peak value of the focus error signal for the + 1st order light or the 0th order light is the threshold value TH2.
After it is determined that the value exceeds, the focus servo is closed (step S54), the tracking servo is closed (step S55), the reproduction is started (step S56), and if there is a stop command, the reproduction is ended (step S54). Step S57; YES).

As described above, for a multilayer DVD,
By storing parameters such as the kick pulse width for jumping the objective lens in advance, unless the disc is replaced thereafter, if the objective lens is jumped based on the stored parameters, it will be accurate and quick. The position can be jumped to a position corresponding to each information recording layer, and correct focus servo control can be performed by discriminating between a multilayer DVD, a single layer DVD, and a CD.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, the focus gain adjustment and the tracking gain adjustment are performed for each layer of a multi-layer DVD, and at the same time, the interlayer spacing is measured.

FIG. 9 is a block diagram showing a schematic structure of the servo circuit 10 of the reproducing apparatus shown in FIG. 1. The other structure of the reproducing apparatus of this embodiment is the same as that of the apparatus shown in FIG.
As shown in FIG. 9, an LPF (Low Pass Filter) 20
Removes unnecessary frequency components higher than the sampling frequency of the A / D converter 22 described later from the focus error signal FE.

The amplifier 21 has a focus error signal FE.
Is amplified to a predetermined voltage value and output, and the amplification amount is changed based on a focus servo gain from the FGA 23 described later.

The A / D converter 22 converts the focus error signal FE amplified by the amplifier 21 into a digital signal, outputs the digital signal to the next FGA 23, and the digitalized focus signal to a servo controller 32 described later. The error signal FE is output.

The FGA 23 feeds back the amplifier 21 on the basis of the focus error signal FE output from the A / D converter 22, and automatically adjusts the focus servo loop gain.

The digital equalizer circuit 24 is composed of a digital filter or the like, and sets a focus servo frequency band corresponding to the focus error signal FE converted into a digital signal based on a control signal from a servo controller 32 described later.

PWM (Pulse Width Modulation) circuit 2
The reference numeral 5 generates a focus drive signal FD having a pulse width according to the signal level from the digital equalizer circuit 24.

Similar to the focus servo loop described above, the LPF 26 and the amplifier 2 are used to generate the tracking drive signal from the tracking error signal TE.
7, an A / D converter 28, a TGA 29, a digital equalizer circuit 30, and a PWM 31 are provided, and the operation corresponding to each unit forming the focus servo loop is performed. Also, to adjust the tracking balance,
Based on a control signal from the servo controller 32, T for automatically controlling the tracking balance
The RBL 33 is provided, and this TRBL 33 adjusts the center level of the tracking error signal.
The signal is fed back to the RF amplifier 3.

The servo controller 32 as the servo calculation means and the servo control means calculates the peak value based on the focus error signal as described later, and sets the focus servo gain from the average of the peak values. A control signal and a control signal for setting the focus servo frequency band are output. Further, it calculates the peak value based on the tracking error signal, and outputs a control signal for setting the tracking servo gain and a control signal for setting the tracking servo frequency band from the average of the peak values. In addition,
A RAM 35 as a storage unit stores data and the like necessary for performing focus servo control and tracking servo control.
Is stored.

The setup operation of the reproducing apparatus of the present embodiment having the servo circuit 10 having the above-mentioned structure will be described below. As shown in FIG. 10, first, it is determined whether or not a disc is set (step S60), and when it is determined that the disc is set, the CPU 9 reads R
Initialization is performed to clear the contents of the AM 13 and to clear the registers included in the CPU 9, for example, the counter N and the counter M described below, and further the timer of the servo controller 32 (step S61).

Next, the disc is discriminated (step S
62). As shown in FIG. 12, in this disc discrimination processing, first, the objective lens is lowered to the lower limit position (step S62-1), and then the objective lens is raised (step S62-2) while the peak of the focus error signal is reached. It is determined whether the value exceeds the threshold TH3 (step S62).
-3). This threshold TH3 is, as shown in FIG.
In this case, the value is set to a value smaller than the peak value of the focus error signal for the 0th order light. In order to obtain the focus error signal as shown in FIG. 13, in the present embodiment, the spectral ratio between the 0th order light and the + 1st order light of the optical pickup 2 is set to, for example, 0th order light: + 1st order light = 70%: 30%. are doing. With this setting, a large focus error signal can be obtained with respect to the 0th-order light regardless of whether the disc is a CD or a DVD. However, the focus error signal in the case of DVD is better than the focus error signal in the case of CD. Also grows. Therefore, when the peak value of the obtained focus error signal exceeds the threshold value TH3 and the threshold value TH1
If it is less than, it can be determined that the disc is a CD, and if it exceeds the threshold TH1, it can be determined that it is a DVD.

Therefore, when the peak value of the focus error signal exceeds the threshold value TH3 (step S62-3;
YES), and it is further determined whether or not the peak value exceeds the threshold TH1 (step S62-4), and when it does not exceed (step S62-4; NO), it is determined to be CD and 1 is stored in the register D. Is set (step S62-
5). On the other hand, when the threshold value TH1 is exceeded (step S
62-4; YES), the operation of the timer T1 is started to determine whether or not the DVD is a multi-layer (step S).
62-6). Then, it is determined whether or not the value of the timer T1 reaches the predetermined value t1 and reaches the upper limit position of the objective lens (step S62-7), and the value of the timer T1 is set to the predetermined value t.
It is again determined whether or not a focus error signal exceeding the threshold TH1 has been obtained before reaching 1 (step S62-
8). In the case of a DVD dual-layer disc, FIG.
As shown in, the threshold value TH is reached before the objective lens reaches the upper limit position.
Since a focus error signal exceeding 1 is obtained (step S62-8; YES), it is determined that the disc is a dual layer disc and 3 is set in the register D (step S62-9). On the other hand, the threshold TH is reached until the timer T1 reaches the predetermined value t1.
When the focus error signal exceeding 1 is not obtained (step S62-7; YES), it is determined that the DVD is a single layer DVD and 2 is set in the register D (step S6).
2-10).

After setting any value in the register D as described above, the timer T1 is ended (step S62-11), and the raising operation of the objective lens is ended (step S62-12). Next, the objective lens is lowered to the lower limit position (step S62-13), and the disc discrimination process is ended.

In the case of this embodiment, two layers of D
The following process is performed only in the case of VD.
This is because the focus gain value and the tracking gain value are different between the one layer and the two layers, so that the focus gain value and the tracking gain value for each layer are stored in order to perform an appropriate focus servo and tracking servo. Is.

Therefore, in order to check the discrimination result in the above disc discrimination processing, as shown in FIG.
Is determined to be 3 (step S63), and if the register D is other than 3 and it is determined to be a single-layer DVD or CD, the same servo close processing as in the second embodiment is performed. (After step S46 in FIG. 7). The processing up to this point is performed by the CPU 9, and the subsequent processing is performed by the servo controller 32 except for specific processing.

On the other hand, when the value of the register D is 3 and it is determined that the DVD is a dual layer DVD, the counter N for counting the number of times the objective lens is moved up and down is incremented to count the focus error signal. The counter M for doing so is incremented (step S6
4).

Then, while raising the objective lens (step S65), it is determined whether or not a focus error signal exceeding the threshold TH1 is detected in the raising process (step S66). The focus error signal exceeding the threshold TH1 is only for the 0th order light.
After disc discrimination of 3 (A), only the focus error signal for the 0th order light is described. Further, in order to make the description easy to understand, the interval of the focus error signal after the disc discrimination processing is drawn wide in FIG. 13 (A).

Next, when a focus error signal exceeding the threshold TH1 is detected (step S66; YE
S), the timers T5 and T10 are operated (step S67).

The timer T5 is used to determine the timing for counting one focus error signal, and the timer T10 is a DVD in which the mounted disc is a multi-layer DVD, as in the first embodiment. In this case, it is used to measure the interlayer distance.

Next, the peak-to-peak value FEpp (M) of the focus error signal is fetched and stored (step S68). This peak-to-peak value FEpp
(M) is used later for focus gain adjustment.

After that, the process waits until the timer T5 exceeds a predetermined value t5 (step S6).
9) If it exceeds, the timer T5 is ended (step S70), it is determined that the output of one focus error signal is ended, and the counter M is incremented (step S71).

Next, it is determined whether or not a focus error signal for the second layer that exceeds the threshold TH1 is detected (step S72), and if such a focus error signal is detected (step S72). S72; YE
S), the operation of the timer T6 is started to measure the distance to the upper limit position of the objective lens (step S73).
At the same time, the operation of the timer T10 for measuring the layer interval is ended (step S74).

Then, the peak-to-peak value FEpp (M) of the focus error signal of the second layer is fetched and stored (step S75). After that, the timer T6 reaches the predetermined value t6 and the objective lens reaches the upper limit position. It waits until it arrives (step S76). After that, this timer T6
When it is determined that has reached the predetermined value t6 and the objective lens has reached the upper limit position (step S76; YES), the timer T6 is ended (step S77).

In the process so far, as shown in FIG. 13 (A), the objective lens reaches the upper limit position, and the counter N for counting the number of times of raising and lowering of the objective lens is 1
Since two focus error signals are detected during this period, the focus error signal counter M is 2. Further, the peak-to-peak value for each focus error signal is also stored.

Next, the objective lens is lowered (step S
78) The counters N and M are incremented (step S79), and it is determined whether or not a focus error signal exceeding the threshold TH1 is detected in the focus error signals for the second layer during the descending process (step S80). When a focus error signal exceeding the threshold TH1 is detected (step S80; YE
S), the operation of the timer T7 for determining the timing for masking the focus error signal is started (step S81), and the peak-to-peak value FEpp (M) of the focus error signal is fetched and stored (step S81).
82).

After that, the process waits until the timer T7 exceeds a predetermined value t7 (step S8).
3) If it exceeds, the timer T7 is ended (step S84), it is determined that the output of one focus error signal is ended, and the counter M is incremented (step S85).

Next, it is determined whether or not a focus error signal for the first layer that exceeds the threshold TH1 is detected (step S86), and if such a focus error signal is detected (step S86). ; YE
S), the operation of the timer T8 is started to measure the distance to the lower limit position of the objective lens (step S8).
7).

Then, the peak-to-peak value FEpp (M) of the focus error signal of the first layer is fetched and stored (step S88), after which the timer T8 reaches the predetermined value t8 and the objective lens reaches the lower limit position. (Step S89), and the value of the timer T8 is the predetermined value t.
When it reaches 8 (step S89; YES), the timer T
8 is completed (step S90).

In the process up to this point, as shown in FIG. 13A, the objective lens reaches the lower limit position, and the counter N for counting the number of times the lens is moved up and down is 2. Since the focus error signal is detected, the focus error signal counter M
Is 4. Further, the peak-to-peak value for each focus error signal is also stored.

After that, the above-mentioned processing is repeated until the counter N reaches 4 (step S91; NO to step S64), and when the counter N reaches 4, the above-mentioned processing is stopped (step S91; YES). Therefore, at this point, four peak-to-peak values of the focus error signals are obtained for the first layer and the second layer, respectively.

Therefore, the focus gain value is calculated and the focus gain is adjusted by calculating the average of the peak-to-peak values of the four focus error signals for each layer (step S92), and the focus of the first layer is adjusted. The gain value and the focus gain value of the second layer are stored in the RAM 3
It is stored in step 5 (step S93).

Next, the CPU 9 determines the layer interval based on the previously measured value of the timer T10 (step S94), and based on the layer interval. At least one of the optimum focus jump pulse width, peak value, braking time, and gain-up time is selected from the table and stored in the RAM 13 (step S95).

Then, the servo controller 32 raises the objective lens (step S96), and first closes the focus servo of the first layer based on the focus gain value of the first layer calculated as described above (step S9).
7). Next, in order to adjust the tracking balance of the first layer, the operation of the timer T12 is started (step S
98), a process for fetching the center level of the tracking error signal TE as shown in FIG.
99) is continued until the value of the timer T12 reaches a predetermined value t12 (step S100; NO), and the timer T1
When the value of 2 reaches the predetermined value t12 (step S100;
If YES, the operation of the timer T12 is ended (step S101), and the tracking balance of the first layer is adjusted according to the value of the center level of the tracking error signal TE fetched as described above (step S10).
2).

Next, in order to adjust the tracking gain of the first layer, the timer T13 is operated (step S
103), the process of fetching the peak-to-peak value TEpp of the tracking error signal TE as shown in FIG. 13B (step S104) is continued until the value of the timer T13 reaches a predetermined value t13 (step S105; N).
O), when the value of the timer T13 reaches the predetermined value t13 (step S105; YES), the timer T13 is stopped (step S106) and the peak-to-peak value TE of the tracking error signal TE fetched as described above.
The tracking gain of the first layer is adjusted according to the value of pp (step S107), the tracking servo is closed (step S108), and the tracking gain value of the first layer is stored in the RAM 35 (step S10).
9).

Next, in order to perform the same processing as described above for the second layer, the lens is moved to the second position on the basis of the previously stored pulse width, peak value, braking time, gain-up time, etc. of the kick pulse. The position of the second layer is jumped to (step S110), and the focus of the second layer is closed based on the focus gain value of the second layer calculated as described above (step S111). Then, in order to adjust the tracking balance of the second layer, the timer T
14 is started (step S112), and FIG.
The processing for fetching the center level of the tracking error signal TE as shown in (C) (step S113) is continued until the value of the timer T14 reaches the predetermined value t14 (step S114; NO), and the value of the timer T14 is set to the predetermined value. When t14 is reached (step S114; YES),
The operation of the timer T14 is terminated (step S11
5) The tracking balance of the second layer is adjusted according to the center level value of the tracking error signal TE fetched as described above (step S116).

Next, in order to adjust the tracking gain of the second layer, the operation of the timer T15 is started (step S117), and the peak-to-peak value TEpp of the tracking error signal TE as shown in FIG. 13 (C). (Step S118) is continued until the value of the timer T15 reaches a predetermined value t15 (step S119;
NO), when the value of the timer T15 reaches the predetermined value t15 (step S119; YES), the operation of the timer T15 is ended (step S120), and the peak-to-peak value TEpp of the tracking error signal TE fetched as described above. The tracking gain of the second layer is adjusted according to the value of (step S121), the tracking servo is closed (step S122), and the tracking gain value of the second layer is stored in the RAM 35 (step S121).
123).

By performing the above-described processing, proper and accurate focus servo control and tracking servo control can be performed for each layer, and the interval between two layers can be measured to determine the optimum jump condition. Can be set, so that an accurate and quick interlayer jump can be performed.

In each of the above-mentioned embodiments, C
The case where the present invention is applied to an apparatus capable of reproducing both D and DVD has been described, but the present invention is not limited to this, and may be a DVD reproduction-only apparatus. Therefore, the optical pickup does not have to use the bifocal lens as described above, and an optical pickup having a single focus lens may be used.
Also, a method of switching the lens of each DVD can be similarly performed.

Further, although the lens movement direction at the time of measuring the layer interval is described as starting from the ascending direction, the present invention is not limited to this, and it may be started from the descending direction.

Further, in the present embodiment, all of the pulse width, peak value, braking time and gain up time of the focus jump are selected and all are stored in the RAM, but the present invention is not limited to this. Instead, any one value or some values may be selected and stored.

Further, in the present embodiment, the focus error signal by the 0th order light is used for obtaining the interlayer spacing of each recording layer, but it is also possible to use the focus error signal by the 1st order light or the pseudo light. . At this time, the interval of the focus error signal is obtained by changing the threshold value appropriately.

In the case of a two-layer double-sided bonded disc, each adjustment is performed for the upper two layers and the lower two layers as in the present embodiment at the time of initial setup, and the layer information of each layer is recorded. It is also possible to keep
Of course, it is also possible to store and use a plurality of respective adjustment values together with the information peculiar to the disc.

[0102]

As described above, according to the information recording medium reproducing apparatus of the first aspect, the moving means of the reading means moves the information recording medium toward or away from the information recording medium. During the period, the appearance interval of the focus error signal exceeding a predetermined reference value is timed, the interlayer distance of the information recording layer is calculated based on the timed result, and the parameter of the control signal for the predetermined moving means is set. Parameters corresponding to the obtained interlayer spacing are selected and stored by the selection storage means, and the information of the plurality of information recording layers is read by controlling the moving means based on the stored parameters. In this case, the objective lens can be moved to the desired information recording layer quickly and accurately, and the information recording medium having a plurality of information recording layers can be smoothly reproduced. It is possible.

According to the reproducing apparatus of the information recording medium of the second aspect, by applying the pulse signal to the moving means, the reading means is moved by a predetermined distance, and the pulse width as the parameter of the control signal is By storing at least one of the peak value, the braking time, and the gain-up time and outputting the control signal to the moving means using the stored parameter, only the desired moving distance, that is, the desired moving distance, The information recording layer can be quickly and accurately moved to the reading position, and the information recording medium having a plurality of information recording layers can be smoothly reproduced.

According to the reproducing apparatus of the information recording medium of the third aspect, when the reading means is moved back and forth, the appearance interval of the adjacent focus error signals among the focus error signals exceeding the predetermined reference value and the information Since the correlation is obtained with the distance from the surface of the recording medium to the information recording layer, the information recording medium can be discriminated based on the appearance interval of the focus error signal by the timing means. When it is determined that the information recording medium is further formed in multiple layers, the calculation of the interlayer spacing as described in claim 1 or claim 2 and the parameter of the control signal based on the calculation result. By the selection and storage, the objective lens can be moved to the desired information recording layer quickly and accurately, and the information recording medium having a plurality of information recording layers can be smoothly reproduced. In addition, focus servo control can be accurately performed according to the type of information recording medium.

According to the reproducing apparatus of the information recording medium of the fourth aspect, the focus gain value and / or the focus gain value is calculated based on the focus error signal and / or the tracking error signal.
Alternatively, when the tracking gain value is calculated and the focus error signal is read, the information recording medium is formed into a multi-layer like the reproducing apparatus of the information recording medium according to any one of claims 1 to 3. Since the calculation of the interlayer spacing of the information recording layers of the information recording medium and the selection and storage of the parameters of the control signal are performed, the information is stored as described above when reading information from a plurality of information recording layers. The desired parameter enables a quick and accurate movement to a desired information recording layer, and further, the focus gain value and / or the tracking gain value recorded as described above allows a quick and accurate focus servo control and / or Since the tracking servo control can be performed, the information recording medium having a plurality of information recording layers can be reproduced more smoothly. Door can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a reproducing apparatus for an information recording medium according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing an example of control signals for the focus driver according to the first embodiment of the present invention.

FIG. 3 is a timing chart showing another example of control signals for the focus driver according to the first embodiment of the present invention.

FIG. 4 is a timing chart showing a moving state of an objective lens of an optical pickup according to the first embodiment of the present invention, a focus error signal obtained at that time, and start and stop of a timer operation.

FIG. 5 is a timing chart showing timing of appearance intervals of focus error signals according to the first embodiment of the present invention.

FIG. 6 is a flowchart of layer spacing measurement control according to the first embodiment of the present invention.

FIG. 7 is a flow chart of layer spacing measurement control in the second embodiment of the present invention.

FIG. 8 is a timing chart showing a moving state of an objective lens of an optical pickup according to a second embodiment of the present invention, a focus error signal obtained at that time, and start and stop of operation of a timer.

FIG. 9 is a block diagram showing a schematic configuration of a reproducing apparatus for an information recording medium according to a third embodiment of the present invention.

FIG. 10 is a flowchart of layer spacing measurement control according to the third embodiment of the present invention.

FIG. 11 is a flowchart of layer spacing measurement control according to the third embodiment of the present invention.

FIG. 12 is a flowchart of a disc discrimination process according to the third embodiment of the present invention.

FIG. 13 is a timing chart showing a moving state of an optical pickup, a focus error signal obtained at that time, and start and stop of timer operation according to the third embodiment of the present invention.

[Explanation of symbols]

 1 ... Optical disc 2 ... Optical pickup 3 ... RF amplifier 4 ... Demodulation / correction circuit 5 ... Spindle motor driver 6 ... Spindle motor 7 ... Video circuit 8 ... Audio circuit 9 ... CPU 10 ... Servo circuit 11 ... Focus driver 12 ... Tracking driver 13 ... RAM 32 ... Servo controller 35 ... RAM

Claims (4)

[Claims] 1. A reproducing apparatus for an information recording medium having a single-layer or multi-layer information recording layer on which information is recorded, comprising an objective lens, and emitting a light beam from the information recording medium to the information recording layer. A reading unit that reads the information recorded in the information recording layer by irradiating and receiving the reflected light, and a relative position of the objective lens of the reading unit and the information recording surface parallel to the optical axis. In order to change the distance, a moving means for moving the objective lens in a direction of approaching or separating from the information recording medium by receiving a control signal, and a read signal based on the read signal by the reading means. Error signal generating means for generating a corresponding focus error signal, and time measuring means for measuring an interval at which the focus error signal appears When a plurality of the focus error signals exceeding a predetermined reference value appear during the movement period of the objective lens in any one direction by the movement means, information based on the time measurement result of the time measurement means Computation means for computing the interlayer spacing of the recording layer, and a parameter corresponding to the interlayer spacing obtained by the computing means from among the parameters of the control signal predetermined for the interlayer movement of the objective lens by the moving means. Selective storage means for selecting and storing, by the parameters stored by the selective storage means,
And a control unit that outputs the control signal to move the objective lens by the moving unit. 2. The moving means is means for moving the reading means by applying a pulse signal, and the parameters of the control signal include pulse width, peak value,
The information recording medium reproducing apparatus according to claim 1, wherein the reproducing apparatus is at least one of a braking time and a gain-up time. 3. Information recording based on a timing result of a timing means for a focus error signal that appears during the reciprocating movement of the reading means by the moving means and exceeds a predetermined reference value. 3. The information recording medium reproducing apparatus according to claim 1, further comprising a discriminating means for discriminating the type of the medium. 4. The error signal generating means is means for generating a tracking error signal based on the received light signal, and based on the focus error signal and / or the tracking error signal generated by the error signal generating means, Servo calculation means for calculating the focus gain value and / or tracking gain value of each layer, storage means for storing the focus gain value and / or tracking gain value obtained by the calculation, and focus gain value stored in the storage means And / or servo control means for performing focus servo control and / or tracking servo control based on the tracking gain value, and the information according to any one of claims 1 to 3. Recording medium reproducing device.