Patent Application
20080205229
The present invention relates to accessing an optical disc, and more particularly, to a method of identifying a loaded optical disc.
One known type of optical disc for storing digital images is the Digital Versatile Disc (DVD), which has been widely used all over the world mainly in storing and delivering multimedia contents. Recently, due to the demand of storing high-quality video/audio contents into a single disc, the development of a disc whose capacity is larger than that of the aforementioned DVD disc has been desired. For example, a next generation DVD disc (e.g., an HD-DVD disc) has been developed to meet user's requirements. However, the conventional DVD disc and the newly developed HD-DVD disc have approximately the same substrate thickness according to respective specifications. Therefore, a conventional optical disc apparatus has difficulty in identifying an inserted optical disc as the conventional DVD disc or the next generation HD-DVD disc if the same means used for efficiently differentiating the compact disc and DVD disc is implemented. As a result, after the optical disc is inserted, the optical disc apparatus has to spend much time upon identifying the correct disc type of the inserted optical disc before starting the data accessing of the optical disc. In other words, the performance of the optical disc apparatus is greatly degraded. A novel scheme of efficiently differentiating the conventional DVD disc and next generation HD-DVD disc is required to shorten the time spent upon identifying the disc type of the inserted optical disc.
It is therefore one of the objectives of the present invention to provide a method of identifying an inserted optical disc, to solve above-mentioned problem.
According to one aspect of the present invention, a method of identifying an optical disc is disclosed. The method includes enabling an optical pick-up unit to emit a first laser beam having a first wavelength to the optical disc; controlling the optical pick-up unit to move a focus point of the first laser beam in a direction of thickness of the optical disc; obtaining a first focus error (FE) signal corresponding to the first laser beam; counting a first s-curve number corresponding to s-curve occurring in the first FE signal; and identifying the optical disc according to the first s-curve number.
According to another aspect of the present invention, a method of identifying an optical disc is disclosed. The method includes enabling an optical pick-up unit to emit a laser beam to the optical disc; enabling a focusing servo control; obtaining a reference signal produced from a reflected laser beam sensed by the optical pick-up unit; when a peak-to-peak voltage of the reference signal is greater than a predetermined voltage, determining that the optical disc complies with a first optical disc specification; and when the peak-to-peak voltage of the reference signal is not greater than the predetermined voltage, determining that the optical disc complies with a second optical disc specification.
According to yet another aspect of the present invention, a method of identifying an optical disc is disclosed. The method includes enabling an optical pick-up unit to emit a blue laser beam to the optical disc; enabling a focusing servo control and a tracking servo control, and moving the optical pick-up unit along a track on the optical disc; obtaining a clock signal produced according to a reflected laser beam sensed by the optical pick-up unit; when a frequency of the clock signal is lower than a predetermined frequency, determining that the optical disc complies with the first optical disc specification; and when the frequency of the clock signal is higher than the predetermined frequency, determining that the optical disc complies with the second optical disc specification.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” The terms “couple” and “couples” are intended to mean either an indirect or a direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
The present invention provides a disc type identifying scheme of an inserted optical disc according to the number of s-curves occurring in a focus error signal, the distance between adjacent s-curves occurring in the focus error signal, a peak-to-peak voltage of an RFRP signal or CRTP signal, and frequency of a data clock or wobble clock. In the following description, the disclosed scheme is capable of identifying an inserted optical disc as a single-layer DVD disc, a dual-layer DVD disc, a single-layer HD-DVD disc, a dual-layer HD-DVD disc, or an HD-DVD/DVD twin format disc. The disc structures of these disc types are illustrated in
Regarding the dual-layer DVD disc shown in
Please refer to
For example, in this embodiment the optical system 105 includes, but not limited to, two laser diodes, a lens set, a photo detector, etc. One laser diode is capable of emitting a red laser beam to access the optical disc 101 when the optical disc 101 is a single-layer DVD disc, a dual-layer DVD disc, or an HD-DVD/DVD twin format disc, and another laser diode is capable of emitting a blue laser beam to access the optical disc 101 when the optical disc 101 is a single-layer HD-DVD disc, a dual-layer HD-DVD disc, or an HD-DVD/DVD twin format disc. The signal processing unit 106 is used for processing an output of the optical system 105 in the OPU 104 to generate a data signal to the data processing unit 108 and servo signals to the control system 122. For instance, the servo signals include a focus error (FE) signal, a tracking error (TE) signal, an RFRP signal, a CRTP signal, or a combination thereof. In this embodiment, the RFRP signal can be generated by passing a main-beam sum signal to a low-pass filer (not shown), passing a sub-beam sum signal to a low-pass filer (not shown), or passing a combination of both to a low-pass filer (not shown). The CRTP signal can be generated by passing a main-beam sum signal to a peak-hold circuit (not shown). That is, the peak-hold circuit detects the envelope of the main-beam peak to generate the CRTP signal.
The data processing unit 108 is used for processing the data signal outputted from the signal processing unit 106 to obtain desired data (e.g., multimedia contents carried by the optical disc 101). The identifying unit 110 is used for identifying the disc type of the optical disc 101 according to above-mentioned servo signals outputted from the signal processing unit 106. For example, the FE signal and the RFRP/CRTP signal are referred to by the identifying unit 110 during the disc type identifying process. The control system 112 is implemented to control the operations of the spindle motor 102 and the OPU 104. The servo controller 126 commands the actuator driver 124 to control a focus actuator of the actuator system 114 for driving the optical system 105 in the OPU 104 to lock a focus point to a recording layer of the optical disc 101 when a focus servo control is enabled; and the servo controller 126 commands the actuator driver 124 to control a tracking actuator of the actuator system 114 for driving the optical system 105 in the OPU 104 to lock a laser spot to a track formed on the recording layer of the optical disc 101 when a tracking servo control is enabled. Additionally, the servo controller 126 controls the motor driver 122 to drive the spindle motor 102 to rotate the optical disc 101 at the desired rotational speed.
It should be noted that the present invention is not limited to support the disc type identification for the aforementioned single-layer DVD disc, dual-layer DVD disc, single-layer HD-DVD disc, dual-layer HD-DVD disc, and HD-DVD/DVD twin format disc. That is, the same concept disclosed by the present invention can be applied to disc type identification for other disc types. Additionally, the identifying unit 110 shown in
Please refer to
In step 700, the flow begins. As mentioned above, the optical system 105 in the OPU 104 has two laser diodes implemented for emitting a red laser beam having a longer wavelength and a blue laser beam having a shorter wavelength, respectively. The control system 112 enables one of the two laser diodes to emit a laser beam onto the optical disc 101. Suppose that the control system 112 firstly enables the optical system 105 in the OPU 104 to emit a red laser beam. Next, the control system 112 enables the actuator driver 124 to control the actuator system 114 (e.g., the focus actuator) to drive the optical system 105 in the OPU 104 to move a focus point of the red laser beam in a direction of thickness of the optical disc 101. It should be noted that the focus servo control is disabled when the focus point of the red laser beam is moving in a direction of thickness of the optical disc 101. In this embodiment, the focus point is controlled to move from an initial position to a destination position downward or upward. The initial position and the destination position should be properly configured for allowing the moving focus point to traverse all possible recording layer(s) formed in the optical disc 101. For example, the initial position and the destination position are defined according to disc structures of those disc types supported by the disclosed disc-type detecting method. In this way, when any of the aforementioned single-layer DVD disc, dual-layer DVD disc, single-layer HD-DVD disc, dual-layer HD-DVD disc, and HD-DVD/DVD twin format disc is loaded, the focus point, which is controlled to move from the initial position to the destination position, is capable of traversing any existing recording layer. Provided that the same objective is achieved, any setting of the initial position and the destination position obeys the spirit of the present invention.
In step 706, the signal processing unit 106 outputs a first FE signal corresponding to the red laser beam according to the reflected laser beam detected by a well-known 4-quadrant photo sensor (not shown) of the optical system 105 in the OPU 104. The FE signal is further processed by the identifying unit 110. In step 708, the identifying unit 110 counts a first s-curve number N1 corresponding s-curve(s) occurring in the first FE signal, wherein the s-curve is induced due to the focus point passing the recording layer. Please refer to
Next, the control system 112 enables the other of the two laser diodes to emit a laser beam onto the optical disc 101. That is, the control system 12 enables the optical system 105 in the OPU 104 to emit a blue laser beam. In the following steps 712-716, the control system 12 enables the actuator driver 124 to control the actuator system 114 (e.g., the focus actuator) to drive the optical system 105 in the OPU 104 to move a focus point of the blue laser beam in a direction of thickness of the optical disc 101, either toward the incidence plane or away from the incidence plane depending upon design requirements; and the identifying unit 110 obtains a second s-curve number N2 corresponding s-curves occurring in the second FE signal and measures a second distance S2 if the second s-curve number N2 is greater than one.
Finally, in step 718, the identifying unit 110 is configured to identify the disc type of the loaded optical disc 101 using at least one of above obtained parameters, i.e., the first s-curve number N1, the second s-curve number N2, the first distance S1, and the second distance S2. Please refer to
As mentioned above, the distance between recording layers 24 and 26 of the dual-layer DVD disc shown in
Briefly summarized, the optical disc 101 is identified as a dual-layer DVD disc when the first s-curve number N1 is equal to 2 and the first distance S1 is greater than the first predetermined threshold value Th_1; the optical disc 101 is identified as a dual-layer HD-DVD disc when the first s-curve number N1 is equal to 2 and the first distance S1 is not greater than the first predetermined threshold value Th_1; the optical disc 101 is identified as an HD-DVD/DVD twin format disc when the first s-curve number N1 is equal to 1, the second s-curve number N2 is equal to 2, and the second distance S2 is greater than the second predetermined threshold value Th_2; the optical disc 101 is identified as a dual-layer HD-DVD disc when the first s-curve number N1 is equal to 1, the second s-curve number N2 is equal to 2, and the second distance S2 is not greater than the second predetermined threshold value Th_2; the optical disc 101 is identified as a single-layer disc (i.e., a single-layer DVD disc or a single-layer HD-DVD disc) when the first s-curve number N1 is equal to 1 and the second s-curve number N2 is equal to 1. In addition, if one of the first s-curve number N1 and the second s-curve number N2 is equal to 0, the optical disc 101 is deemed to have a disc type not supported by the DVD specification and the HD-DVD specification.
As shown in
After studying above disclosure in reference to
When the optical disc 101 is identified as a single-layer disc (step 905), the present invention can further activate a sub-flow to discriminate between the single-layer DVD disc and single-layer HD-DVD disc. Please refer to
In step 1102, the optical system 105 in the OPU 104 is driven by the control system 112 to emit either a red laser beam or a blue laser beam according to design requirements. In step 1104, the motor driver 122 of the control system 112 is activated to enable the spindle motor 102 to start rotating the optical disc 101. Next, the servo controller 126 of the control system 112 activates the focus servo control. Please note that the tracking servo control remains disabled in this case. At the same time, the signal processing unit 106 processes the signals outputted from the optical system 105 in the OPU 104 to generate the aforementioned RFRP signal or CRTP signal due to the movement of the OPU 104, and the identifying unit 110 measures a peak-to-peak voltage VPP of the incoming RFRP/CRTP signal (step 1110). Because the characteristics of the single-layer DVD disc and the single-layer HD-DVD disc, the single-layer DVD disc makes the RFRP/CRTP signal have a greater peak-to-peak voltage. Therefore, the identifying unit 110 compares the measured peak-to-peak voltage VPP and a predetermined voltage VTH to discriminate between the single-layer DVD disc and the single-layer HD-DVD disc (steps 1112, 1114, 1116).
Please refer to
In step 1202, the optical system 105 in the OPU 104 is driven by the control system 112 to emit a laser beam having a shorter wavelength (i.e., the blue laser beam). In step 1204, the motor driver 122 of the control system 112 is activated to enable the spindle motor 102 to start rotating the optical disc 101. Next, the servo controller 126 of the control system 112 activates both of the focus servo control and the tracking servo control. In step 1210, the actuator driver 124 of the control system 112 controls the actuator system 114 to move the OPU 104 along a track formed on the recording layer of the optical disc 101. At the same time, the signal processing unit 106 processes the signals outputted from the optical system 105 in the OPU 104 to generate a data clock or wobble clock through a phase-locked loop (PLL), and the identifying unit 110 measures a frequency FR of the data clock/wobble clock (step 1212). Because the data density of the single-layer HD-DVD disc is greater than that of the single-layer DVD disc, the frequency of the data clock/wobble clock corresponding to the HD-DVD disc is higher than that corresponding to the DVD disc. Therefore, in this embodiment, the identifying unit 110 compares the measured frequency FR and the predetermined frequency FTH to discriminate between the single-layer DVD disc and the single-layer HD-DVD disc (steps 1214, 1216, 1218).
For the sake of brevity, how to identify the optical disc will be described below in detail and the other portion of the flow will be omitted. After the optical disc is identified as a DVD disc (step 1312), and in step 1322, if the first s-curve number N is greater than one, identify the optical disc as a dual-layer DVD disc; otherwise, identify the optical disc as a single-layer DVD disc. After the optical disc is identified as an HD-DVD disc (step 1314), and in step 1322, if the s-curve number N is greater than one, identify the optical disc as a dual-layer HD-DVD disc; otherwise, identify the optical disc as a single-layer HD-DVD. Please note that, the laser beam in this embodiment is a red laser beam or a blue laser beam.
For the sake of brevity, how to identify the optical disc will be described below in detail and the other portion of the flow will be omitted. After the optical disc is identified as a DVD disc (step 1416), and in step 1424, if the first s-curve number N is greater than one, identify the optical disc as a dual-layer DVD disc; otherwise, identify the optical disc as a single-layer DVD disc. After the optical disc is identified as an HD-DVD disc (step 1418), and in step 1424, if the s-curve number N is greater than one, identify the optical disc as a dual-layer HD-DVD disc; otherwise, identify the optical disc as a single-layer HD-DVD.
Please note that if the result is substantially the same, the steps are not limited to be executed according to the exact order shown in the disclosed drawing. For instance, the timing of executing the step of enabling the spindle motor to rotate the optical disc can be changed according to design requirements. Taking the flow shown in
