JPH0944895A - Optical pickup, optical recording medium and information reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bifocal optical pickup, an optical recording medium and an information reproducing device hardly reading out a reflection light and the reflection light from a multi-layer signal surface when information is reproduced from the optical recording medium. SOLUTION: The distance from a surface of a substrate of a first optical recording medium to its signal surface is defined W1, and the distance from the surface of the substrate of a second optical recording medium to its signal surface is defined W2 (W2>W1). Then, distance FD of these two focal positions is given by FD=W1×K (K is a coefficient having a value of 0.2-0.8) or FD>W1, and FD=W2×K+W1×(1-K).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a CD (compact disc), an MD (mini disc), a laser disc,
An information reproducing device (information recording device for reproducing a 1.2 mm thick disc such as a magneto-optical disc or a 0.6 mm thick disc such as a DVD (digital video disc) with a common bifocal optical pick. And an optical pickup for optically reading a signal for reproduction, and is also applied to a multilayer optical card and other optical recording media.

[0002]

2. Description of the Related Art Conventionally, various kinds of optical recording media have been developed or put into practical use, but the thickness of the substrate of these media is also various. For example, in Japanese Unexamined Patent Publication No. 7-65407, the convergence point of an objective lens that converges light on an optical recording medium is 2
A technique is disclosed in which two optical pickup media having different thicknesses are recorded and reproduced by a bifocal pickup.

[0003]

However, during focus search, two signals are detected by the bifocal pickup, and discs having different thicknesses such as CD and DVD can be shared and played. However, depending on the interfocal distance, There may be a problem that a focal point that is not originally imaged on the signal recording surface (called a signal surface) is imaged on the disk surface or the like.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art. When recording / reproducing on / from an optical recording medium by a bifocal optical pickup, the reflected light from the surface of the optical recording medium or the multi-layer structure is used. It is an object of the present invention to obtain an optical pickup, an optical recording medium, and an information reproducing apparatus for recording / reproducing information without reading the reflected light from the signal surface.

[0005]

In order to achieve the above object, in the optical pickup according to the present invention, the distance between two focal points is defined by the thickness of the optical recording medium (the substrate which is the substrate of the medium). It is set in relation to the distance from the surface to the signal surface).

That is, according to the present invention, there is provided an optical pickup for reading information respectively recorded on two types of optical recording media, a first type and a second type, which have different distances from the surface of the substrate to the signal surface. A laser beam generating means, a focusing means for focusing the laser beam generated by the laser beam generating means on two different focal positions of the two types of optical recording media, and a plurality of receiving means for receiving reflected light from the optical recording medium. In an optical pickup having a sensor divided into two, the distance from the surface of the substrate of the first optical recording medium to its signal surface is W1, and from the surface of the substrate of the second optical recording medium to its signal surface. Is W2 (W2> W1), the two focal position distances FD are: FD = W1 × K (K is 0.2 to 0) Coefficient) or FD> W1, and the optical pickup being characterized in that the value given by FD = W2 × K + W1 × (1-K) has a value of 8. Is provided.

According to the present invention, the distance from the substrate surface to the signal surface of each of the first optical recording medium having the two-layer signal surface and the second optical recording medium having the one-layer signal surface. And an optical pickup for reading information recorded on two types of optical recording media, each of which has a different laser beam generation means, and a laser beam generated by the laser beam generation means for each of the two types of optical recording media. In an optical pickup having a focusing means for focusing on two different focus positions and a plurality of divided sensors for receiving reflected light from the optical recording medium, one closer to the surface of the substrate of the first optical recording medium. W1 is the distance to the first signal surface of the substrate, and W3 is the maximum distance from the first signal surface to the second signal surface farther from the surface of the substrate. When the distance from the surface of the substrate of the second optical recording medium to the signal surface is W2 (W2> W1), the two-focus distance FD is FD <W1-2 × W3 and FD> 2 × W3 and FD = 2 × W3 + W1 × K (K is a coefficient having a value of 0.2 to 0.8) or FD> W1 + 2 × W3, FD <W2, and FD = 2 × W3 + W2 × K + W1 × (1- An optical pickup is provided, which has a value given by K).

Further, according to the present invention, in an optical recording medium in which information is optically recorded / reproduced on signal surfaces of a plurality of layers, the nth signal (n is an integer of 1 or more) from the surface of the substrate of the medium. Adjacent to the surface, the distance W (n− from the n-th to (n−p) -th (p is an integer of 1 or more) signal surface
p) and the n-th (n is an integer of 1 or more) signal surface, and the distance from the n-th to (n + m) -th (m is an integer of 1 or more) signal surface is W (n + m). ) (M is an integer of 1 or more), W (n−p) ≠ W (n + m), the optical recording medium is provided.

In the above optical recording medium, the distance between the signal surfaces can be set to gradually increase or decrease from the surface of the substrate of the medium to the signal surface of the uppermost layer.

Further, according to the present invention, there is provided an information reproducing apparatus having the above optical pickup.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical pickup, an optical recording medium and an information reproducing apparatus according to the present invention will be described with reference to preferred examples. FIG. 1 is a block diagram showing a schematic configuration of a DVD / CD common player as an information recording / reproducing apparatus having an optical pickup of the present invention. In FIG. 1, a disc-shaped disc 1 as an optical recording medium has a track formed in a spiral shape from the inner circumference to the outer circumference, and the optical pickup 2 gives a laser beam spot to this track. Predetermined information is reproduced optically. In the case of an optical disc device having a recording function,
Recording and playback are performed. This disc 1 is servo-controlled by a servo control circuit 4 via a preamplifier 3 on the basis of a signal read and reproduced by an optical pickup 2, and a C by a motor drive 6 and a spindle motor 7.
It is rotated at LV (constant linear velocity).

The optical pickup 2 constitutes an optical head together with a magnetic modulation head (not shown) when a recording function is added, but the example of FIG. 1 will be described as a read-only machine. Only the optical head (in the case of a recording / reproducing apparatus) or the optical pickup 2 (in the case of a reproducing-only apparatus) can be moved by the motor drive 6 in the radial direction of the disk 1. Also, disk 1
Has a laser diode which emits light to output the signals RF1 and RF2 for reproducing the optical information recorded based on the reflected light, and the four-divided focus error signal detection signals A to A of the astigmatism method. D and two tracking error signal detection signals E and F of the 3-beam method are output. These signals are input to the preamplifier 3.

FIG. 2 shows the sensor parts ABCDEFIJ of the optical pickup 2 in the form of a quadrangle, and the light spot incident on them is shown in the form of a circle. The direction indicated by arrow Y is the longitudinal direction of the track, and the direction indicated by arrow X is the radial direction of the disk 1 perpendicular to the longitudinal direction of the track. The optically reproduced signals A to F, RF1 and RF2 are output from the respective sensor portions, and are used when the optical pickup 2 is subjected to tracking and focusing control with respect to the track of the disc 1.
It is used for reproducing the FM signal.

The preamplifier 3 is provided with the signals RF1 and RF.
2 and an EFM signal based on the focus error signal detection signals AD (= A + B + C + D) and a focus error signal FE (= for detecting the shift of the spot of the reflected light based on the focus error signal detection signals A to D. A + B
-CD) is calculated, and the tracking error signal TE is calculated based on the tracking error signal detection signals E and F.
(= FE) is calculated and output to the servo control circuit 4 and the system controller 5.

During reproduction, the servo control circuit 4 demodulates the EFM signal based on the output signals from the preamplifier 3 and the system controller 5 to perform error correction decoding, and at the same time, based on the focus error signal FE and the tracking error signal TE, an optical signal is output. The pickup 2 controls via the motor driver 6 so as to track and focus on the track of the disc 1.

The system controller 5 as the servo-on means includes an A / D converter for taking in various signals A to F from the preamplifier 3, a focus error signal FE and a tracking error signal TE, and a laser diode in the optical pickup 2, for example. A PWM unit for controlling the output power of the laser diode by driving with a signal according to a 12-bit PWM signal, a RAM for a work area, etc.
A ROM for programs and the like, a CPU and the like (not shown) are built in, and an error signal for focusing control of 4-division ABCD astigmatism and tracking control of 3-beam EF is obtained from the preamplifier 3 and at the same time, 2 By setting an inter-focus distance, disc type is discriminated during focus search, servo is turned on in a predetermined reflected light region based on the discrimination result, and a control command for position and speed of the optical pickup 2 is given to the servo control circuit 4. Servo control is performed so that the reproduced signal is caused to follow the PLL, and EFM digital data decoding and error correction processing are performed.

The motor driver 6 controls the optical pickup 2 and the spindle motor 7, and includes a preamplifier 3, a servo control circuit 4 and a system controller 5.
Together with this, it constitutes a servo control means as two positioning means in tracking and focus control.

Thus, in the servo system, the preamplifier 3
A motor driver 6 generates a tracking error signal based on a plurality of outputs of the sensor of the optical pickup 2 and returns the tracking error signal to the optical pickup 2 so that the optical pickup 2 is moved to the disk 1.
Tracking servo means for positioning in the radial direction, focus servo means for generating and returning a focus error signal based on a plurality of outputs of the sensor, and positioning the optical pickup in the focus direction, a plurality of focus servo means during focus search. The type of the disc is discriminated based on the detection of the reflected light, and the servo-on control means for turning on (servo-on) the servo control by the servo control means while focusing on a predetermined reflected light area based on the discrimination result To do.

Here, the focus is the focus error signal FE of A + C-B-D based on the output obtained by I / V converting and amplifying each output of the 4-division ABCD sensor by the astigmatism method, and tracking is performed. The output of each of the three-beam EF sensor is I / V converted and amplified, and the tracking error TE of EF, which is based on the amplified output, is A / D converted and digitally servo-processed. It is composed of a feedback loop for outputting and driving the focus coil and the tracking coil by the motor driver 6.

The block structure shown in FIG. 1 is common to the optical recording / reproducing apparatus, and recording / reproducing using a CD, DVD, MO, MD or PC (phase change type disk) is performed by the following processing method. It can be commonly applied to devices such as devices. For example, refer to JP-A-7-65407,
It is assumed that the focus optical pickup 2 reproduces two types of discs having plate thicknesses W1 and W2, and the numerical aperture of the objective lens for forming a light spot on the disc 1 is NA = 0.45.
The CD spot with the plate thickness W1 = 1.2 mm is reproduced while the spot with the numerical aperture NA = 0.6 is the plate thickness W1 = 1.2 mm.
It is assumed that a DVD of 2 = 0.6 mm is reproduced, and an inter-focus distance FD of two focal points is FD1 = 0.3 in the case of the first embodiment.
mm, in the case of the second embodiment, FD2 = 0.9 mm, 2
The setting of the inter-focus distance FD will be described in detail.

FIG. 3 shows the state transition of the two focal points that move when the current is gradually applied to a focus coil (not shown) of the optical pickup 2 to raise the optical pickup 2, and FIG. And b are the plate thickness W in the first embodiment in which the distance between the two focal points is FD1 = 0.3 mm.
In case of 1 = 1.2 mm disc and plate thickness W2 = 0.6 m
In the case of a disk of m, and c and d in FIG.
It shows a case of a disk having a plate thickness W1 = 1.2 mm and a case of a disk having a plate thickness W2 = 0.6 mm in the second embodiment in which the focal distance between the focal points is FD2 = 0.9 mm.

Here, the two-focal distance FD cannot be the same as the thickness because when the image is formed at the same time as the disk surface and the signal surface, the disk surface is affected by modulation and offset at low frequencies. Especially, in Fig. 3b, the plate thickness W
In order not to form an image on the surface of the second disc,
Due to the non-uniformity of the thickness of the disc and the state near the surface of the disc, the distance FD between the two focal points is 0.
It should be about 2 to 0.8 times. In the example, 0.
It is set to 3 mm. In other words, the formula is as follows. FD = W1 × K (K is a coefficient, 0.2 to 0.8)

Alternatively, in c and d of FIG. 3, FD> W1 so that the image is not formed on the plate thickness W2 but is formed on the plate thickness W1.
(0.6 mm) and FD = W1 + (W2-W1) * (0.2-0.8) That is, it is set at an intermediate position of the plate thickness W2. This is expressed by the following equation. FD = W2 × K + W1 × (1-K). Here, the refractive index in the disk is not taken into consideration for drawing (generally, since the refractive index changes, it needs to be taken into consideration).

Next, FIG. 4 shows the setting of the interval between two focal points in the case where a disc having a plate thickness of 0.6 mm has two layers of signal surfaces and a disc having a plate thickness of 1.2 mm has one layer of signal surfaces. It is a figure for explaining. In this case, the interlayer distance W3 of the two-layer disc is the maximum interlayer distance even among a plurality of layers. Even if the distance between the signal surfaces is, for example, 50 μm,
Depending on the manufacturing method, for example, when the thickness varies by about ± 10 μm or when two layers are adhered by laminating, the transmittance and the refractive index may not be stable in the central part, and the two focal lengths FD are If an image is formed on the signal layer at the same time as the disk surface and the signal surface, it cannot be performed because the disk surface is affected by low frequency modulation and offset.

Therefore, as shown in FIG. 4A for reproducing the first layer of the plate W1 disc, FD> 2 × W3 is required to form the reflected light of the second layer of the preceding focus on W1. 4b, FD + 2 × W3 <W1 needs to be satisfied because the reflected light of the first layer is imaged on W1. In this state, the focal points of a, b, and c in FIG. 4 are 0.2 above W1.
Preferably between 0.8 and 0.8. Similarly, in d and e of FIG. 4, FD> W1 + 2 × W3, and F
It is necessary that D <W2. In this state, d and e of FIG.
It is desirable that the focus of is between 0.2 and 0.8 above W2.

That is, the distance from the surface of the substrate (transparent layer such as polycarbonate or glass constituting the disk) of the first disk having the two signal surfaces to the first signal surface is W1, the first signal is When the maximum distance from the surface to the second signal surface is W3 and the distance from the surface of the substrate of the second disc to the signal surface is W2 (W2> W1), the two-focal point spacing FD is FD < W1-2 × W3, and FD> 2 × W3, and FD = 2 × W3 + W1 × K (K is 0.2 to 0.8) or FD> W1 + 2 × W3, and FD <W2, and FD = 2 × W3 + W2 It is desirable to set to × K + W1 × (1-K). Here, the refractive index in the disk is not taken into consideration for drawing (generally, since the refractive index changes, it needs to be taken into consideration). Further, in the case of a multilayer, the reflection when the second layer of the preceding focus of FIG. 4A returns to the first layer reduces the reflection in the opposite direction on the disc, so that it is directly on the first layer. It does not matter if it is not imaged.

Next, FIG. 5 is a diagram for explaining the setting of the interlayer distance in the case of a disc having a plurality of layers of signal surfaces. It can be easily understood from FIG. 5C that the distance between the signal planes is the same in the range of variation when the signal planes of five layers are provided as shown in a and b of FIG. In addition, when the signal of the fifth layer is read, images are formed on the second and fourth layers, and although the reflection in the opposite direction is reduced, the distance between the signal surfaces is 50%.
Even if it is μm, it varies about 10 μm, which is not desirable.

Therefore, in FIGS. 5A and 5B, the distance between the signal planes is changed layer by layer to prevent focusing. In this case, the above variations should be excluded so that they do not overlap. Generally, if the sum of adjacent layers in all layers including variations is not equal to the sum of oppositely adjacent layers, two focal points do not match. For example, in FIGS. 5A and 5B, when W4 is used as a reference, if W4 ≠ W3, W4 ≠ W3 + W2, and W4 ≠ W3 + W2 + W1, then focus is not achieved. Similarly, when W3 is used as a reference, W3 ≠ W
If 2, and W3 ≠ W2 + W1, then no focus is achieved. Further, when W3 + W4 is used as a reference, W3 + W
If 4 ≠ W2 and W3 + W4 ≠ W1 + W2, no focus is achieved. That is, it is adjacent to the n-th (n is an integer of 1 or more) signal surface from the surface of the substrate of the disc, and is the n-th to (n-p) -th signal surface (p is an integer of 1 or more). To a distance W (n−p) and an nth (n is an integer of 1 or more) signal surface, and an nth to (n + m) th signal surface (m is an integer of 1 or more) When the distance to is W (n + m) (m is an integer of 1 or more), W (n−p) ≠ W (n + m).

The distance between the signal planes is set to be gradually longer or shorter from the surface of the substrate to the signal plane of the uppermost layer, as shown in FIG. 5A or 5B. As shown in a and b of FIG. 5, the distances W1 and W between the signal surfaces are
The ratio of 2, W3, W4 is "2, 3, 4, 5", "5, 4,"
"3,2" or "2,3,4,2" or "1,3,5,"
If the ratio of the prime numbers is 7 ”, the focus will not be achieved. As the ratio of the distances, at least the ratio between the distances exceeding the range of variation may be used.

In the above embodiment, when performing a well-known focus search operation on the basis of a plurality of outputs of an optical pickup having a plurality of divided sensors for receiving the reflected light from the disc, a plurality of reflected lights are detected during the focus search. The type of the disc is discriminated based on the detection, and the servo control by the servo control means for positioning the optical pickup in the focusing direction is focused on a predetermined reflected light region based on the discrimination result (focus servo control loop). Is a closed loop). The disc type can be determined by measuring at least two or more time intervals of the reflected light amount signal or two or more reflected light amount levels. It is a preferable aspect of the information reproducing apparatus of the present invention to further provide servo-on means for turning on the servo control by the servo control means in a state of focusing on a predetermined reflected light area by using the discrimination result, and the system controller 5 of FIG. It can be easily realized by the internal microcomputer.

Although each of the above embodiments has been described by taking the information reproducing apparatus as an example, it is needless to say that the present invention can be directly applied to an information recording / reproducing apparatus which also has a recording function.

[0032]

As described above, according to the optical pickup and the information reproducing apparatus of the present invention, the two focus points of the optical pickup are prevented from reading the reflected light from the medium surface and the reflected light from the multilayer signal surface. Since the interval is set, there is no problem that the focal point, which is not originally imaged on the signal surface, is imaged on the disk surface or the like, and the same optical pickup is used for disks with different thicknesses such as CD and DVD. Alternatively, the information reproducing apparatus can be shared and reproduced.

Further, according to the optical recording medium of the present invention, the distance between the signal surfaces of the multi-layer disc is changed by one layer so that the focal point is not focused. Therefore, the focal point which is not originally imaged on the signal surface is the disc surface. It is possible to avoid the influence between the signal surfaces without causing a problem by forming an image on the image plane.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a DVD / CD common player as an information reproducing apparatus having an optical pickup of the present invention.

FIG. 2 is a sensor portion ABCD of the optical pickup 2 of FIG.
It is explanatory drawing which shows that EFIJ is each shown with the square and the state that the light spot is injecting into them with a circle.

FIG. 3 shows a state transition of two moving focal points and setting of an interval between two focal points when a current is gradually applied to a focus coil (not shown) of the optical pickup 2 of FIG. 1 to raise the optical pickup 2. It is an explanatory view explaining.

FIG. 4 relates to the present invention, in which a disc having a plate thickness of 0.6 mm has two layers of signal surfaces, and a disc having a plate thickness of 1.2 mm has a signal layer of one layer, It is an explanatory view for explaining setting.

FIG. 5 is an explanatory diagram relating to the optical recording medium of the present invention and illustrating setting of the interlayer distance in the case of a disc having a plurality of layers of signal surfaces.

[Explanation of symbols]

1 disk (optical recording medium) 2 optical pickup 3 preamplifier 4 servo control circuit (servo control means together with preamplifier, motor driver and system controller) 5 system controller (servo-on means) 6 motor driver 7 spindle motor (rotational drive means) )

Claims (7)

[Claims] 1. An optical pickup for reading information recorded on two types of optical recording media, first and second, having different distances from the surface of the substrate to the signal surface, the laser pickup including: Focusing means for focusing the laser beam generated by the laser beam generating means on two different focal positions of the two types of optical recording media, and a sensor divided into a plurality of parts for receiving reflected light from the optical recording medium In the optical pickup, the distance from the surface of the substrate of the first optical recording medium to its signal surface is W1, and the distance from the surface of the substrate of the second optical recording medium to its signal surface is W2 ( W
2> W1), the two focus position distances FD
Is FD = W1 × K (K is a coefficient having a value of 0.2 to 0.8) or FD> W1 and FD = W2 × K + W1 × (1-K) Optical pickup to do. 2. A first optical recording medium having a two-layered signal surface and a second optical recording medium having a single-layered signal surface are provided with two types of substrates each having a different distance from the surface to the signal surface. An optical pickup for reading information recorded on an optical recording medium, comprising laser beam generating means,
Focusing means for focusing the laser beam generated by the laser beam generating means on two different focal positions of the two types of optical recording media, and a sensor divided into a plurality of parts for receiving reflected light from the optical recording medium. In the optical pickup, the distance from the surface of the substrate of the first optical recording medium to the nearer first signal surface is W1, and the distance from the first signal surface to the second signal surface far from the surface of the substrate. To W3, and the distance from the surface of the substrate of the second optical recording medium to the signal surface is W2 (W2> W1)
, The inter-focal distance FD is FD <W1-2 × W3, and FD> 2 × W3, and FD = 2 × W3 + W1 × K (K is a coefficient having a value of 0.2 to 0.8). ) Or FD> W1 + 2 × W3, and FD <W2, and FD = 2 × W3 + W2 × K + W1 × (1-K). 3. An optical recording medium in which information is optically recorded / reproduced on a signal surface of a plurality of layers, adjacent to an n-th (n is an integer of 1 or more) signal surface from the surface of a substrate of the medium, Adjacent to the distance W (n-p) from the n-th to the (n-p) -th signal surface (p is an integer of 1 or more) and the n-th (n is an integer of 1 or more) signal surface Then, when the distance from the n-th to the (n + m) -th (m is an integer of 1 or more) to the signal surface is W (n + m) (m is an integer of 1 or more), W (n−p) ≠ An optical recording medium characterized by being W (n + m). 4. The optical recording according to claim 3, wherein the distance between the signal surfaces gradually increases or decreases from the surface of the substrate of the medium toward the signal surface of the uppermost layer. Medium. 5. A means for rotating a disc which is an optical recording medium, and two focal points for reproducing data by a laser beam with respect to two types of discs having different plate thicknesses,
An optical pickup having a plurality of divided sensors for receiving reflected light from the disc, and a tracking error signal generated based on a plurality of outputs of the sensor and returned to position the optical pickup in the radial direction of the disc. In addition, in an information reproducing apparatus having a servo control means for generating and returning a focus error signal based on a plurality of outputs of the sensor and positioning the optical pickup in the focus direction, the optical pickup is provided from the surface of the substrate. A laser beam generating means and a laser beam generated by the laser beam generating means for respectively reading information recorded on two types of optical recording media, first and second, having different distances to the signal surface. To two different focal positions of the above two types of optical recording media. Focusing means for focusing and a plurality of divided sensors for receiving the reflected light from the optical recording medium, and the distance from the surface of the substrate of the first optical recording medium to its signal surface is W1, When the distance from the surface of the substrate of the second optical recording medium to its signal surface is W2 (W2> W1), the two focal position distances FD are: FD = W1 × K (K is 0.2 An coefficient having a value of 0.8) or FD> W1 and FD = W2 × K + W1 × (1−K). 6. A means for rotationally driving a disc which is an optical recording medium, and two focal points for reproducing data by a laser beam with respect to two types of discs having different plate thicknesses,
An optical pickup having a plurality of divided sensors for receiving reflected light from the disc, and a tracking error signal generated based on a plurality of outputs of the sensor and returned to position the optical pickup in the radial direction of the disc. In addition, in the information reproducing apparatus having a servo control means for generating and returning a focus error signal based on a plurality of outputs of the sensor to position the optical pickup in the focus direction, the optical pickup has a two-layer signal surface. Information recorded on two types of optical recording media having different distances from the surface of the substrate to the signal surface of the first optical recording medium having the signal layer and the second optical recording medium having the signal layer of one layer, respectively. A laser beam generating means for reading, and the laser beam generating means. Focusing means for focusing the laser beam on two different focal positions of the two types of optical recording media, and a plurality of divided sensors for receiving reflected light from the optical recording medium, The distance from the surface of the substrate of the recording medium to the nearer first signal surface is W1, the maximum distance from the first signal surface to the farther second signal surface is W3, and the second distance The distance from the substrate surface of the optical recording medium to the signal surface is W2 (W2> W
1), the two-focus distance FD is FD <W1-2 × W3, and FD> 2 × W3, and FD = 2 × W3 + W1 × K (K is a value of 0.2 to 0.8). The information reproducing apparatus is characterized in that FD> W1 + 2 × W3, FD <W2, and FD = 2 × W3 + W2 × K + W1 × (1−K). 7. The servo control by the servo control means is turned on while disc type is discriminated based on detection of a plurality of reflected lights during focus search and the disc is focused on a predetermined reflected light region based on the discrimination result. 7. The information reproducing apparatus according to claim 5, further comprising: a servo-on means for realizing the above.