JPS647426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a digital audio disc player, and more particularly to a search control circuit for performing a search operation for target information recorded on a disc at high speed and with high accuracy.

BACKGROUND TECHNOLOGY A digital audio disk player plays back a disk on which digitalized audio signals, synchronization signals, etc. are optically recorded at high density at a constant linear velocity. It has special features. The information recording portion of this digital audio disk is composed of a lead intra track, a data track, and a lead out track, and the lead intra track includes the music number and music information recorded on the data track. The start time signals are recorded sequentially to form a table of contents. Furthermore, a music number, a total running time signal, data (musical tone signal), etc. are recorded on the data track by repeating a signal in which one frame has a predetermined number of bits.

Therefore, if you want to selectively start playback from the desired music number part, read the music number recorded on the data track while moving the pickup at high speed, and start playing the music number specified by this music number. When the search number matches, the search operation ends and the normal playback operation begins.

However, in the above-mentioned search operation, there is a limit to the speed of movement because the pick-up must be moved while reading the music number, and this causes the problem that the search takes a long time. have.

DISCLOSURE OF THE INVENTION Accordingly, an object of the present invention is to provide a digital digital camera which has a simple configuration and yet can perform a search operation for a target music number at high speed and with high precision.
An object of the present invention is to provide a search control circuit for an audio disc player.

In order to achieve such an object, the present invention provides a microprocessor that generates a write request signal and a read request signal of input/output request signals, and a first processor that detects coincidence between the input/output request signal and the read request signal. a first address decoder that is enabled by the output signal of the gate circuit and decodes the address signal supplied from the microprocessor to generate first and second address enable signals; and the input/output request signal and the read signal. a second address decoder that is enabled by the output signal of the second gate circuit that detects coincidence of the request signals and outputs a third address enable signal by decoding the address signal; and a second address decoder that outputs a third address enable signal by decoding the address signal; a first output buffer circuit connected to the setter and actuated by the first address enable signal to generate a signal for fast forwarding or fast reversing the pick-up feed motor; a second output buffer circuit connected to the pickup circuit and enabled by the second address enable signal to generate a signal to send or return the optical system of the pickup in the radial direction; an input buffer circuit that takes in overrun signals for the forward and return directions of radial control for the optical system of the optical system and supplies them to the microprocessor via a data bus, the microprocessor By reproducing the table of contents recorded in the table of contents, information for the specified start time is retrieved, and a signal corresponding to the total travel time at the present moment is extracted from the reproduction signal to calculate the difference between the current position of the pick-up and the target position. The feed amount of the pick-up is calculated from this difference information and the pick-up feed motor is driven to perform a rough search to locate the target position within the tracking control range of the optical system installed in the pick-up, and then read. Controls the pick-up to match the destination by performing a fine search that performs tracking control of the optical system according to the difference between the second signal of the specified total traveling time and the second signal of the specified start time of the information. It is.

When such a search device is used, the pick-up feed motor is driven according to the difference between the pick-up's target position and the current position to move the pick-up closer to the target position. There is no need to read information, and accordingly, the pick-up feeding speed can be sufficiently increased. Then, when the pick-up is positioned within the minimum feed range of the pick-up feed motor with respect to the target position, tracking control is performed on the optical system installed in the pick-up to align the pick-up to the target position. This means that highly accurate searches can be performed.
Therefore, although it has a simple configuration, it has the excellent effect of being able to perform a highly accurate search operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing an embodiment of a search control circuit for a digital audio disc player according to the present invention. In the figure, 1 is a microprocessor that sends input/output request signals.
Output port P ₁ that generates IOR, output port P ₂ that generates a write request signal, output port P ₃ that generates a read request signal, port group P ₄ to which address bus AB is connected, and data bus DB are connected. It has a port group _P4 . 2 is an OR gate that generates the chip enable signal ₁ by inputting the input/output request signal and read request signal generated from the microprocessor 1; and 3, the input/output request signal and the write request signal are input. Chip enable signal ₂
4 is an address decoder that decodes the address signal supplied from microprocessor ₁ via address AB when chip enable signal 1 is generated, and generates address enable signals ₁ and _2. 5 is a chip enable signal. An address decoder 6 decodes the address signal and generates an address enable signal ₃ when the signal ₂ is generated, and an address decoder 6 operates when the address enable signal ₁ is generated to convert the signal supplied via the data bus DB to a pick-up (not shown). Output buffer circuit that supplies fast forward signal FF or fast reverse signal REW to the feed motor drive circuit, 7 is a data signal when address enable signal ₂ is generated
An output buffer circuit converts the DB and supplies a sending signal F or a return signal R to a tracking control circuit (not shown) that controls tracking for the optical system of the pickup; 8 is an address enable signal;
This input buffer circuit takes in overrun signals FO and RO for tracking control in the forward and return directions in the pick-up optical system when AE ₃ occurs, and supplies them to the microprocessor 1 via the data bus DB. The overrun signals FO and RO are output signals of a comparator that compares the level of a control signal supplied from a tracking control circuit (not shown) to a tracking coil of an optical pickup with predetermined upper and lower limit values. Alternatively, the output signal of a pickup configured to output an overrun signal is used.

The operation of the circuit with the above configuration will be explained below using the flowchart shown in FIG.

First, when a disc is set in a digital audio disc player, it automatically reads the lead intratrack information and stops playing. In this case, since table of contents information is recorded in the lead intratrack, the music number and its start time information recorded in the data track are read and stored in the memory provided inside the microprocessor 1. is memorized.

Next, when the operator specifies the music number and turns on the start button, the search mode is automatically entered and a rough search shown at step _S1 in FIG. 2 is started, and the process moves to step _S2 .
In step _S2 , a muting circuit (not shown) is turned on to prevent noise from occurring during the search, and a spindle motor that rotates the disk at a constant linear velocity and a laser oscillator used for information reading are driven. .

Next, the microprocessor 1 executes step _S3
By taking in the reproduction signal of the disc read in step _S4 , it is determined whether or not the current pick-up reading position is the lead intratrack. in this case,
Since special information bits are recorded in the lead intratrack, it is easy to identify it. If the result of this determination is YES, the process moves to step _S5 , where the output buffer circuit 6 generates one fast-forward signal FF for the pick-up feed motor to make the optical pick-up move one step, and then step S5 is started. Move to ₃ . In this case, to send the fast forward signal FF, the microprocessor 1 generates an input/output request signal and a write request signal, thereby causing the OR gate ₂ to generate the chip enable signal 1 and enabling the address decoder 4. In this state, when an address signal designating the output buffer circuit 6 is generated, an address enable signal ₁ is generated from the address decoder 4 and the output buffer circuit 6 is enabled.

Therefore, at this point, the microprocessor 1 supplies the output buffer circuit 6 with an address signal and a data signal instructing generation of the fast-forward signal, thereby generating the fast-forward signal FF.

By repeating these operations, the pickup advances one step at a time, moving from the lead intra track to the data track. and,
When the information recorded in the lead intratrack is read out, the microprocessor 1 makes a YES judgment in step _S4 shown in FIG. 2, and proceeds to step _S6 . In step _S6 , the total running time signal included in the signal read out from the data track is taken in, and the start time signal of the previously specified music number is read out from the memory, and the minutes of the total running time signal are read out. The signal is compared with the current location information AMin, and the minute signal of the start time signal is used as the destination location information PMin. If the two match, it is assumed that the rough search has been completed and the fine search in step _S7 is started. If the determination in step _S6 is NO, the process moves to step _S8 , where the magnitude relationship between the two is determined. Here, if the judgment in step _S8 is YES, the difference between the two is calculated in step _S9 , and a number of fast-forward signals FF corresponding to this difference are generated in step _S10 . After that, the process returns to step _S3 . Therefore, the pick-up feed motor is driven in accordance with the number of fast-forward signals FF to move the pick-up toward the destination at high speed. By repeating such operations, the current location information AMin and the destination location information PMin match, and the process moves to step _S7 . If the judgment in step _S8 is NO, the difference between the two is calculated in step _S11 , and a number of fast rewind signals corresponding to this difference are generated.
REW is outputted from the output buffer circuit 6 in the same manner as in the case described above, and the pickup is returned at high speed to find a match in step _S6 .

Next, when the fine search is started in step _S7 , the current location second information ASec and destination second information PSec are compared in step _S13 , and if they match, a pick-up is specified. Assuming that the music number is located at the beginning of the music number, the process moves to step _S14 and returns.
On the other hand, if the determination in step _S13 is NO, the process proceeds to step _S15 , where the magnitude relationship between both signals is determined. And the steps
If the judgment in _S15 is YES, the process moves to step _S16 to find the difference between the two, and the number of sending signals F corresponding to this difference is sent to the output buffer circuit 7 in step _S17 . is output from.

In this case, the sending of the feed signal F is the fast forward signal FF.
Similarly to the above case, this is done by supplying the output buffer circuit 7 with an address signal and a data signal instructing the sending of the sending signal F in synchronization with the address enable signal _AE2 . When the sending signal F is generated, a tracking control circuit (not shown) that controls tracking for the pickup optical system performs tracking sending control in accordance with the number of sending signals F. When such tracking control is performed, there may be cases where the tracking control range is exceeded and the signal cannot be read sufficiently. For this purpose, in step _S18 ,
Captures the overrun signal FO. When capturing the overrun signal FO, the microprocessor 1 generates an input/output request signal and a read request signal, and the chip enable signal ₂ is output from the OR gate 3.
is generated to enable the address decoder 5. In this state, microprocessor 1
When the address decoder 5 generates an address signal specifying the input buffer circuit 8, the address enable signal ₃ is generated from the address decoder 5 and the input buffer circuit 8 is enabled. Next, in step _S19 , the overrun signal FO
is active, and if the answer is YES, the overrun state of the tracking control is resolved by executing an operation in which the pick-up feed motor is sent by one pulse in step _S20 . In step S ₂₁ after
Determine whether AMin and PMin match. Further, if the determination in step _S19 is NO, the process directly proceeds to step _S21 . If the determination in step _S21 is YES, the process returns to step _S13 and a match between ASec and PSec is determined in fine search mode. Moreover, if the judgment in step _S21 is NO, the process returns to step _S8 , and after the operation of matching AMin and PMin in rough search mode is executed, the process shifts to fine search mode. . By repeating such operations, if AMin and PMin and ASec and PSec match, it is assumed that the pickup is located at the destination, and the search operation is terminated and normal reproduction operation begins. If the comparison result in step _S15 is negative, the difference between the two is determined in step _S22 , and an operation is performed to return the tracking in the optical system of the pick-up according to the value of this difference. is performed in step _S23 . Thereafter, in step _S24 , the overrun signal RO for the return direction is fetched, and in step _S25 it is determined whether or not this overrun signal RO is active. Then, if the judgment in step _S25 is yes,
The pick-up feed motor is driven in the return direction by one pulse and the process moves to step _S21 . Also,
If the determination at step _S25 is no, the process directly moves to step _S21 .

When such a search control circuit is used, the tracking control of the pick-up feed motor and the pick-up optical system can be driven without reading information, so the search operation becomes extremely fast and is faster than the conventional one. In comparison, it is about one-sixth or less.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a search control circuit for a digital audio disc player according to the present invention, and FIG. 2 is a flowchart showing the operation of the circuit shown in FIG. 1... Microprocessor, 2, 3... OR gate, 4, 5... Address decoder, 6, 7...
...Output buffer circuit, 8...Input buffer circuit.

Claims (1)

[Claims] 1. A microcomputer that captures the disc playback signal read by the pick-up;
first and second address decoders each driven by write and read control signals of the microcomputer to decode address signals;
It is driven by the first address enable signal generated from the first address decoder, and inputs the address signal and data signal supplied from the microprocessor to fast-forward and fast-reverse the pick-up feed motor. A first output buffer circuit generates a control signal, and is driven by a second address enable signal generated from the first address decoder to pick up an address signal and a data signal supplied from the microprocessor. a second output buffer circuit that generates tracking sending and returning control signals for the optical system of the pickup; and a second output buffer circuit that is driven by an address enable signal generated from the second address decoder to send tracking in the optical system of the pickup. and an input buffer circuit that takes in overtracking signals in the direction and backward direction and supplies them to the microcomputer, and the microprocessor receives a signal specified from a playback signal of table of contents information recorded in the lead intratrack of the disk. The start time signal of the information is taken in, and the total traveling time signal at the present moment is taken in from the playback signal, and the difference between the current position and the target position is calculated from the difference between the two minute signals, and the pick-up feed motor is fast-forwarded according to this difference. Or, when the rough search is completed to locate the destination within the tracking control range of the optical system of the pick-up by fast reversing, the second signal in both the start time signal and the current total traveling time signal is A search control circuit for a digital audio disc player, characterized in that a fine search is performed to match the two by tracking and controlling the optical system of the pickup according to the difference between the two.