JP3816053B2 - High-density optical disk reading method and high-density optical disk apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a high-density optical disk reading method and a high-density optical disk apparatus for reading data from a high-density optical disk whose capacity is increased by increasing the type of reflectance of laser light.
[0002]
[Prior art]
  Optical discs such as CDs, CD-Rs, and CD-RWs are widely used for storing digital data such as music data.
  However, in recent years, there has been an increase in demand for storing image data on an optical disc, but the amount of image data is particularly large, and the capacity of a conventional optical disc may be insufficient. In addition to the image data, the capacity of all data has been increasing in recent years, and the capacity of the conventional optical disk has become insufficient.
  Therefore, a technique for increasing the capacity of the optical disc as compared with the conventional optical disc has been developed.
[0003]
  In the conventional optical disc, pits are formed on the recording surface of the optical disc, and the reflectance of the laser beam is different between the portion where the pit is formed and the portion where the pit is not formed. Therefore, depending on the difference in the reflectance of the laser beam, that is, the presence or absence of pits, 0 or 1 can be expressed, and information can be recorded as digital data. Called an optical disc).
[0004]
  On the other hand, the high-density optical discs that are currently being developed can increase the number of types of laser light reflectivity by providing several levels of pits, and can record as much information as the type of reflectivity. It is a thing.
  For example, as shown in FIG. 5, the pit sizes are set to 8 types from pits a to h. In this case, the reflectivity reflected from the optical disk is 8 (2 to the power of 3), and the data represented by three pits in the past can be represented by one pit. The amount of information that is three times that of the prior art can be recorded (see Non-Patent Document 1).
[0005]
  Since a high-density optical disc has a recording format different from that of a conventional single-density optical disc, a completely different data format is employed.
  FIG. 6 shows an example of the data format of a high-density optical disk in which the types of laser light reflectivity are increased to eight.
  In this data format, a high-density optical disc has a lead-in area on the inner circumference side and a user data area on the outer circumference side. In addition, the address allocated to the recording area has a zero wobble address at the boundary between the lead-in area and the user data area, a negative wobble address less than 0 in the lead-in area, and a wobble of zero or more in the user data area. Each address is allocated.
[0006]
  The lead-in area is composed of a power correction area, a disk information recording area, and a copy protection area. These are provided in the order of the power correction area, the disk information recording area, and the copy protection area from the inner circumference side of the high-density optical disk. The wobble address where each area is arranged varies depending on the size of the high-density optical disk. For example, in the case of a 120 mm disk, the power correction area is -5120 to -1531 wobble address, and the disk information recording area is -1520 to -21 wobble address. The copy protection area is allocated to -20 to -1 wobble addresses, respectively (note that the -1530 to -1521 wobble addresses between the power correction area and the disk information recording area are neutral zones).
[0007]
  The power correction area is an area for the optical disc apparatus to irradiate and pick up a laser beam to establish optimum irradiation laser power, focus, tracking, and the like.
[0008]
  The disc information recording area is an area for writing disc information related to user data written in the user data area. The disc information includes information such as writing position information of each user data on the user data area.
  In the disc information written in the disc information recording area, the user data number assigned in the recording order of each user data and the start address and end address of each user data as the write position information of each user data in the user data area, etc. include.
  As shown in FIG. 7, every time user data is written in the user data area, the latest disc information is sequentially written from the outer circumference side to the inner circumference side of the disc information recording area.
[0009]
  The copy protection area is an area where data writing is prohibited.
[0010]
[Non-Patent Document 1]
          TDK Corporation, “TDK Media Tech Report 3rd“ Multi-level (ML) recording technology to triple the capacity of CD-R / RW ””, p. 1-4, [online], Heisei November 14, 2013, TDK Corporation (November 14, 2002), <URL: http://www.tdk.co.jp/mediatech/index.htm>
[0011]
[Problems to be solved by the invention]
  A high-density optical disk reading method and a high-density optical disk apparatus for reading and writing data from and to the high-density optical disk are currently under development. This high-density optical disk reading method and high-density optical disk apparatus have a problem that the latest disk information in the disk information recording area can be surely accessed and the written user data can be quickly accessed.
[0012]
  Further, a high-density optical disk device connected to a host computer is expected to have a certain compatibility in interface with a conventional optical disk device. In particular, a host computer compatible only with a conventional optical disk apparatus may transmit a read TOC command to the optical disk apparatus in order to recognize the contents of the optical disk inserted into the optical disk apparatus when executing the initialization process. Many. Therefore, there is a problem that it is necessary to appropriately respond to the read TOC command from the host computer.
[0013]
  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to read a high-density optical disk that can reliably access the latest disk information in the disk information recording area and can quickly access written user data. It is an object to provide a method and a high density optical disc apparatus.
  It is another object of the present invention to provide a high-density optical disk apparatus connected to a host computer and having a certain compatibility with a conventional optical disk apparatus.
[0014]
[Means for Solving the Problems]
  In order to solve the above-described problems, a high-density optical disc reading method according to the present invention has the following configuration. In other words, the capacity of the laser beam is increased by increasing the type of laser light reflectivity, and a disc information recording area is provided for writing disc information including user data writing position information. Is read from a high-density optical disk in which the disk information is sequentially written from the outer peripheral side to the inner peripheral side of the disk information recording area, A disc information reading step for searching for the latest disc information as the latest disc information and reading the latest disc information by seeking data from the innermost circumference to the outer circumference side of the disc information recording area; The latest disk information read in the information reading step is stored in memory. Disc information storage step stored in the disc information storage step, based on the write location information included in the latest disc information stored in the disc information storage step, to specify a specific user data write location on the high-density optical disc, And a user data reading step of reading the specific user data by reading the data at the writing position.
  According to this, the latest disc information can be surely read out by seeking data from the innermost circumference to the outer circumference side of the disc information recording area and reading the disc information first seeked. In addition, the latest disk information read out is stored in the storage means, and the user data is accessed based on the stored latest disk information. Therefore, every time the user data is accessed, the latest disk information is read from the high-density optical disk. User data can be accessed quickly without having to seek.
[0015]
  In order to solve the above-described problems, a high-density optical disc apparatus according to the present invention has the following configuration. In other words, the capacity of the laser beam is increased by increasing the type of laser light reflectivity, and a disc information recording area is provided for writing disc information including user data writing position information. Is a high-density optical disk apparatus capable of reading data from a high-density optical disk in which the disk information is sequentially written from the outer periphery side to the inner periphery side of the disk information recording area, Disc holding means capable of holding the data, and seeking the data from the innermost circumference to the outer circumference of the disc information recording area of the high-density optical disc held by the disc holding means. Disc information that searches for the latest disc information and reads the latest disc information Based on the write position information included in the latest disk information stored in the disk information storage means and the latest disk information stored in the disk information storage means, the disk information storage means for storing the latest disk information read by the disk information reading means, User data reading means for reading the specific user data by specifying the write position of the specific user data on the high-density optical disk and reading the data at the write position is provided.
  According to this, the latest disc information can be surely read out by seeking data from the innermost circumference to the outer circumference side of the disc information recording area and reading the disc information first seeked. Further, since the read latest disk information is stored in the disk information storage means and user data is accessed based on the stored latest disk information, the latest disk is read from the high-density optical disk every time the user data is accessed. There is no need to seek information, and user data can be accessed quickly.
[0016]
  Further, a read command comprising a communication unit capable of communicating with a host computer, wherein the user data reading means instructs to read user data at a specific position on the high-density optical disc from the host computer and transmit it to the host computer Is received, it is determined whether or not user data has been written at the specific position based on the write position information included in the latest disk information stored in the disk information storage means. The user data at the specific position read based on the write position information, the error information indicating that the user data has not been written at the specific position if not written, It transmits to a host computer, It is characterized by the above-mentioned.
  According to this, when a read command instructing to read user data at a specific position of the high-density optical disk is received from the host computer, the specific position is determined based on the latest disk information stored in the disk information storage means. If no user data is recorded, error information is sent to the host computer, and the area in the user data area where no user data is recorded is not read. There is no.
[0017]
  MaA communication unit communicable with a host computer; disk discriminating means for discriminating whether the optical disc held by the disc holding means is a single density optical disc or the high density optical disc; TOC reading means for transmitting to the computer; and TOC reading alternative means for transmitting data based on the latest disk information stored in the disk information storage means to the host computer, and the disk holding means by the disk determination means. When it is determined that the optical disk held in the disk is a single density optical disk, when the host computer receives a read TOC command instructing that the TOC of the single density optical disk is read and transmitted to the host computer And reading the TOC When the TOC is read from the single density optical disk by the ejecting means and transmitted to the host computer, and the optical disc held by the disc holding means is discriminated by the disc discriminating means as the high density optical disc, When the host computer receives a read TOC command instructing to read the TOC of a single density optical disk and send it to the host computer, the TOC read substitute means sends the data based on the latest disk information to the host computer. It is characterized by transmitting to.
  According to this, a high-density optical disk apparatus capable of reading data from a single-density optical disk and a high-density optical disk, the host computer being used regardless of whether the single-density optical disk is used or the high-density optical disk is used. Thus, when a read TOC command for reading the TOC of a conventional optical disc is received, information corresponding to the command can be returned to the host computer.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
  Preferred embodiments of a high-density optical disk reading method and high-density optical disk apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
[0019]
  FIG. 1 is a block diagram showing a configuration of a high-density optical disc apparatus A according to the present embodiment.
  The high-density optical disk apparatus A is communicably connected to a host computer H such as a personal computer. The high-density optical disc apparatus A does not necessarily have to be physically separated from the host computer H. For example, the high-density optical disc apparatus A is built in the housing of the host computer H, and the main board of the host computer H is installed in the host computer H. Etc. may be connected.
  Further, the high-density optical disk apparatus according to claim 2 of the present invention includes not only one connected to a host computer but also a high-density optical disk apparatus that operates alone, such as a music player.
[0020]
  The internal configuration of the high-density optical disc apparatus A will be described with reference to FIG. In FIG. 1, a solid line arrow indicates a control flow, and a broken line arrow indicates a data flow.
  The high-density optical disk apparatus A includes a disk holding means 22 that holds an optical disk D such as a high-density optical disk, a spindle motor 24 that rotates the optical disk D via the disk holding means 22, and a laser that irradiates the optical disk D with its reflection. Hardware such as a pickup 28 for reading light is provided.
[0021]
  The high-density optical disc apparatus A includes a control unit (not shown) configured by a CPU, a memory, a logic circuit, firmware, and the like. The control unit includes a communication unit 2, a command analysis execution unit 4, a TOC reading unit 8, a user data reading unit 10, a disc determination unit 12, a TOC reading alternative unit 14, a disc information reading unit 16, a motor driver 26 and a pickup driver 30. Is included. In addition, a storage area constituting the disk information storage unit 20 is secured on a memory such as a RAM of the control unit.
[0022]
  An optical disk that reads data from an optical disk D by a disk holding means 22, a spindle motor 24, a motor driver 26 that controls the spindle motor 24, a pickup 28, and a pickup driver 30 that controls the position and laser irradiation of the pickup 28. Reading means 18 is configured.
[0023]
  The disc discriminating unit 12 is configured as firmware for discriminating whether the optical disc D held by the disc holding unit 22 is a single density optical disc or a high density optical disc.
  The disc discriminating unit 12 is activated every time the optical disc D is inserted into the high-density optical disc apparatus A by the user and held by the disc holding unit 22, and reads the recording format of the optical disc D through the optical disc reading unit 18. It is determined whether D is a single density optical disk or a high density optical disk, and the determination result is stored in a storage means such as a RAM. Further, the disc determination unit 12 includes a determination result notification unit (not shown), and can notify the stored determination result to other units that have called the determination result notification unit.
  Further, when disc discriminating means 12 discriminates that optical disc D is a high density optical disc, disc discriminating means 16 described later is activated.
[0024]
  The disc information reading means 16 as the disc information reading means is the latest disc information (latest disc information) as the latest disc information (latest disc information) from the optical disc D (high density optical disc) held in the disc holding means 22. Is configured as firmware for reading out.
  The disc information reading unit 16 is activated when the user inserts the optical disc D into the high density optical disc apparatus A and the disc discrimination unit 12 determines that the optical disc D is a high density optical disc. The disc information reading means 16 is connected to the outer peripheral side from the innermost circumference (−1520 wobble address in the case of a 120 mm high-density optical disc) of the disc information recording area provided in the lead-in area of the optical disc D via the optical disc reading means 18. The data is sought toward the disk, and the disc information detected first is stored in the disc information storage means 20 as the disc information storage means.
[0025]
  The communication unit 2 is configured as a logic circuit and firmware having a function of receiving data transmitted from the host computer H and transmitting data in the high-density optical disc apparatus A to the host computer H.
[0026]
  The command analysis execution unit 4 is configured as firmware that analyzes the data string received by the communication unit 2 and recognizes it as a command, and causes each unit in the control unit to execute a predetermined process according to the type of command. Further, the command analysis execution means 4, when data to be transmitted to the host computer H is generated as a result of processing by each means, converts the data into a data string of a predetermined format via the communication unit 2. To the host computer H.
  In the present embodiment, for the sake of simplicity of explanation, the commands analyzed and executed by the command analysis execution means 4 describe only the read command and the read TOC command, but the types of commands are limited to this. However, it is possible to analyze a larger number of commands.
[0027]
  The TOC reading unit 8 is configured as firmware for reading the TOC from the optical disc D. When the TOC reading unit 8 is activated, it first calls the discrimination result notifying unit of the disc discrimination unit 12 to check the type of the disc.
  When the optical disk D held by the disk holding means 22 is a single density optical disk, the TOC is read from the optical disk D via the optical disk reading means 18, and the read TOC is converted into the command analysis execution means 4 and the communication unit 2. To the host computer H. The TOC includes the number of each user data written on the optical disc D (POINT), the start position (start time) of user data corresponding to each number, the number of the first user data (first movement number), and the last Contains the user data number (last movement number).
  On the other hand, when the optical disk D is a high-density optical disk, the TOC reading unit 8 activates the TOC reading alternative unit 14.
[0028]
  The TOC reading substitute unit 14 is configured as firmware and is activated by the TOC reading unit 8.
  The TOC read substitution unit 14 creates data to be transmitted to the host computer H in response to the read TOC command based on the disc information stored in the disc information storage unit 20. The TOC data transmitted to the host computer H is created as follows based on the disc information.
  Each user data number included in the disc information is substituted for each user data number in the TOC.
  A numerical value obtained by time-converting the start address of each user data included in the disc information is substituted for the start position (start time) of the user data corresponding to the number of each user data in the TOC. Since one wobble address includes data for 1/75 second, the address can be converted to time by converting 1 wobble address as 1/75 second.
  The number of the first recorded user data among all user data included in the disc information is substituted for the number of the first user data in the TOC.
  The number of the last recorded user data among all the user data included in the disc information is substituted for the number of the last user data in the TOC.
[0029]
  The user data reading means 10 is configured as firmware, and when the command analysis execution means 4 analyzes a read command instructing that user data at a specific position on the optical disc D is read and transmitted to the host computer H, command analysis is performed. It is activated by the execution means 4. The user data reading unit 10 recognizes the type of the optical disc D by the discrimination result notifying unit of the disc discrimination unit 12.
  When the optical disk D is a single density optical disk, the user data reading unit 10 reads the TOC from the optical disk D via the TOC reading unit 8.
  On the other hand, when the optical disk D is a high density optical disk, the user data reading means 10 reads disk information from the disk information storage means 20.
  The user data reading means 10 determines whether or not user data is written at a specific position specified by the read command from the write position information included in the TOC or disc information. If the user data read from the specific position via the optical disk reading means 18 is not written, error information indicating that it is a read command for an area where no user data is written is indicated by command analysis execution means. 4 and the communication unit 2 to the host computer H.
[0030]
  Next, the operation of the high-density optical disc apparatus A will be described with reference to FIGS.
[0031]
  As shown in FIG. 2, when the user inserts the optical disc D into the high-density optical disc apparatus A in a disc non-inserted state (S1), the disc discriminating means 12 is activated. The disc discriminating unit 12 reads the data recording format of the optical disc via the optical disc reading unit 18, discriminates whether the optical disc D is a single density optical disc or a high density optical disc, and stores the discrimination result in a storage unit such as a RAM (not shown). (S2).
[0032]
  The disc discriminating unit 12 further activates the disc information reading unit 16 when the discrimination result is a high density optical disc.
  The disc information reading means 16 is connected to the outer peripheral side from the innermost circumference (−1520 wobble address in the case of a 120 mm high-density optical disc) of the disc information recording area provided in the lead-in area of the optical disc D via the optical disc reading means 18. The data is sought for (disc information reading step S3), and the disc information detected first is stored in the disc information storing means 20 (disc information storing step S4).
[0033]
  Here, as shown in FIG. 7, the disc information of the high-density optical disc is sequentially written from the outer circumference side to the inner circumference side of the disc information recording area every time user data is written in the user data area. Therefore, the disc information written on the innermost side is the latest disc information (latest disc information). Accordingly, data is sought from the innermost circumference to the outer circumference of the disc information recording area, and the disc information detected first and stored in the disc information storage means 20 is surely the latest disc information.
[0034]
  Thereafter, the high-density optical disc apparatus A enters a standby state in which it waits for a user operation or a command from the host computer H.
[0035]
  As shown in FIG. 3, when the host computer H issues a read TOC command in the standby state, if the command analysis execution means 4 recognizes the read TOC command, the command analysis execution means 4 causes the TOC read means 8 to to start. The TOC reading unit 8 recognizes whether the optical disc D is a single density optical disc or a high density optical disc by the discrimination result notifying unit of the disc discrimination unit 12 (S11).
[0036]
  When the optical disk D is a single density optical disk, the TOC reading unit 8 reads the TOC from the optical disk D via the optical disk reading unit 18 (S12), and the contents of the TOC are transmitted to the command analysis execution unit 4 and the communication unit. 2 to the host computer H (S13).
[0037]
  On the other hand, when the optical disc D is a high-density optical disc, the TOC reading unit 8 activates the TOC reading alternative unit 14. The TOC read substitution means 14 creates the data to be transmitted to the host computer H in response to the read TOC command based on the latest disk information (S14) read from the disk information storage means 20 (S15). (S16).
[0038]
  As shown in FIG. 4, when the host computer H issues a read command instructing that user data at a specific position on the optical disc D is read and transmitted to the host computer H in the standby state, command analysis is performed. When the execution unit 4 recognizes the read command, the command analysis execution unit 4 activates the user data reading unit 10. The user data reading means 10 recognizes whether the optical disk D is a single density optical disk or a high density optical disk by the determination result notifying means of the disk determination means 12 (S21).
[0039]
  When the optical disk D is a single density optical disk, the user data reading means 10 reads the TOC of the optical disk D by the TOC reading means 8 and recognizes the writing position of each user data included in the TOC (S22).
  On the other hand, when the optical disk D is a high density optical disk, the user data reading means 10 reads the latest disk information from the disk information storage means 20, and recognizes the writing position of each user data included in the latest disk information ( S23).
  The user data reading means 10 determines whether or not user data is written at the specific position specified by the read command based on the writing position information included in the TOC or disc information (S24). If so, the user data is read from the specific position via the optical disk reading means 18 (user data reading step), and the user data is transmitted to the host computer H (S25). If no user data is written at the specific position, error information indicating a read command for an area where no user data is written is transmitted to the host computer H (S26).
[0040]
  According to the high-density optical disk reading method and high-density optical disk apparatus A according to the present embodiment, data is sought from the innermost circumference to the outer circumference of the disk information recording area, and the first-sought disk information is obtained. By reading, the latest disk information can be read reliably. Further, since the read disk information is stored in the storage means 20 such as a RAM and the user data is accessed based on the stored latest disk information, the latest disk is read from the high-density optical disk every time the user data is accessed. There is no need to seek information, and user data can be accessed quickly.
[0041]
  Further, according to the high density optical disc apparatus A according to the present embodiment, when a read command instructing to read user data at a specific position of the high density optical disc is received from the host computer H, the disc information storage means 20 If no user data is recorded at the specific position based on the latest disk information stored in the error information, error information is transmitted to the host computer H, and the user data area in which no user data is recorded Is not read out, so that the high-density optical disk apparatus A does not hang.
  Further, when a read TOC command for reading the TOC of the conventional optical disk is received from the host computer H, information corresponding to the command is returned to the host computer H, so that there is a certain compatibility with the conventional optical disk apparatus. Kept.
[0042]
  In this embodiment, the disc information reading unit 16 is configured to be activated by the disc discriminating unit 12 when the optical disc D is inserted into the high-density optical disc apparatus A. The read timing of the disk information is not limited to this. For example, when the read TOC reading unit 8 is activated, it may be activated by the read TOC reading unit 8 to read disc information from the optical disc D.
[0043]
  In the present embodiment, the user data is read from the optical disc D when the read command is received. However, the timing at which the user data reading means 10 is activated and the user data reading step S25 is executed is as follows. For example, the user data can be read out and transmitted to the host computer H or the user data such as music can be reproduced at the timing when a reproduction button (not shown) of the high-density optical disc apparatus A is pressed. It may be configured.
[0044]
  In the present embodiment, the high-density optical disk reading method and the high-density optical disk apparatus A corresponding to the high-density optical disk having the data format shown in FIG. 6 have been described. However, the present invention is not limited thereto, The present invention can be applied to all types of high-density optical discs in which disc information is sequentially written from the outer peripheral side to the inner peripheral side of the disc information recording area each time user data is written in the user data area. .
[0045]
【The invention's effect】
  According to the high-density optical disk reading method and high-density optical disk apparatus of the present invention, it is possible to reliably access the latest disk information in the disk information recording area and to quickly access the written user data. Furthermore, according to the high-density optical disk apparatus of the present invention, it is possible to maintain a certain compatibility with the conventional optical disk apparatus and the interface when connected to the host computer.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an internal configuration of a high-density optical disc apparatus according to the present invention.
FIG. 2 is a flowchart showing processing when an optical disc is inserted into a high-density optical disc according to the present invention.
FIG. 3 is a flowchart showing processing when the high-density optical disc apparatus according to the present invention receives a read TOC command.
FIG. 4 is a flowchart showing processing when the high-density optical disc apparatus according to the present invention receives a read command.
FIG. 5 is an explanatory diagram for explaining a concept for increasing the capacity of an optical disc.
FIG. 6 is an explanatory diagram showing an example of a data format of a high-density optical disc.
FIG. 7 shows how disk information is written in the disk information recording area of the high-density optical disk, and the high-density optical disk reading method and high-density optical disk apparatus according to the present invention search for disk information in the disk information recording area. It is explanatory drawing which shows a mode.
[Explanation of symbols]
  A High-density optical disk device
  D Optical disc
  H Host computer
  2 Communication Department
  4 Command analysis execution means
  8 TOC reading means
  10 User data reading means
  12 Disc discriminating means
  14 TOC readout alternative means
  16 Disc information reading means
  18 Optical disk reading means
  20 Disc information storage means
  22 Disc holding means
  24 Spindle motor
  26 Motor driver
  28 Pickup
  30 Pickup driver
  S3 Disc information reading step
  S4 Disc information storage step
  S25 User data reading step

Claims (4)

The capacity is increased by increasing the types of laser light reflectivity,
A disc information recording area which is an area for writing disc information including user data writing position information is provided,
Reads data from a high-density optical disk in which the disk information is sequentially written from the outer periphery side to the inner periphery side of the disk information recording area each time user data is written to the user data area. A method,
Disc information reading step for searching the latest disc information that is the latest disc information and reading the latest disc information by seeking data from the innermost circumference to the outer circumference side of the disc information recording area;
A disk information storage step for storing the latest disk information read in the disk information reading step in a storage means;
Based on the writing position information included in the latest disk information stored in the disk information storing step, a specific user data writing position on the high-density optical disk is specified, and data at the writing position is read out. And a user data reading step for reading out the specific user data. The capacity is increased by increasing the types of laser light reflectivity,
A disc information recording area which is an area for writing disc information including user data writing position information is provided,
A high-density optical disc capable of reading data from a high-density optical disc in which the disc information is sequentially written from the outer peripheral side to the inner peripheral side of the disc information recording area each time user data is written in the user data area A device,
Disk holding means capable of holding an optical disk;
By seeking data from the innermost circumference to the outer circumference of the disc information recording area of the high-density optical disc held in the disc holding means, the latest disc information that is the latest disc information is searched, Disk information reading means for reading the latest disk information;
Disk information storage means for storing the latest disk information read by the disk information reading means;
Based on the write position information included in the latest disk information stored in the disk information storage means, a specific user data write position on the high-density optical disk is specified, and data at the write position is read out. And a high-density optical disk apparatus comprising user data reading means for reading the specific user data. It has a communication unit that can communicate with the host computer,
The user data reading means includes
When a read command is received from the host computer to instruct user data at a specific position on the high-density optical disk to be read and transmitted to the host computer, the latest disk information stored in the disk information storage means is It is determined whether or not user data is written at the specific position based on the writing position information included, and if it is written, the user at the specific position read based on the writing position information is written. 3. The high-density optical disk apparatus according to claim 2, wherein when data is not written, error information indicating that user data is not written at the specific position is transmitted to the host computer. A communication unit capable of communicating with the host computer;
Disc discriminating means for discriminating whether the optical disc held by the disc holding means is a single density optical disc or the high density optical disc;
TOC reading means for reading TOC from a single density optical disk and transmitting it to the host computer;
TOC reading alternative means for transmitting data based on the latest disk information stored in the disk information storage means to the host computer,
When the disc discriminating unit discriminates that the optical disc held by the disc holding unit is a single density optical disc,
When the host computer receives a read TOC command instructing to read the TOC of a single density optical disk and send it to the host computer, the TOC reading means reads the TOC from the single density optical disk to the host computer. Send
When the disc discriminating unit discriminates that the optical disc held by the disc holding unit is the high-density optical disc,
When the host computer receives a read TOC command instructing to read the TOC of a single density optical disk and send it to the host computer, the TOC read substitute means sends the data based on the latest disk information to the host computer. The high-density optical disk apparatus according to claim 2 or 3, wherein

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