KR100209408B1 - Focus search apparatus for use in a mini disk player - Google Patents

Abstract

The present invention relates to a focus search apparatus of a mini-disc player, which is provided from an optical pickup unit (410) and an optical pickup unit (410) for converting and outputting light reflected from the disk (400) into a pickup and a current signal. The IV converter 420 converts and amplifies the current signal into a voltage signal and outputs the voltage signal. The voltage signal provided from the 1-V converter 420 is compared with the reference signal, and if the reference signal is larger than the reference signal, the comparison signal is calculated accordingly. The comparison unit 430 and the counter unit 440 which generate the focus OK signal when the count value is 2 and the comparison signal provided from the comparison unit 430 is counted, and the focus unit is supplied from the counter unit 440. When the OK signal is provided, a control signal is generated accordingly. The microcomputer 450 outputs a clock signal for resetting the counter unit 440 to the counter unit 440 and the microcomputer 450 provided from the microcomputer 450. Focus search according to the control signal It includes a focus controller 460 to provide a focus servo signal to the optical pickup unit 410, and configuration.

Therefore, the present invention has the advantage that the focus search can be executed in the same way as the CD in the MD, and the failure of the focus search can be prevented and the operation time of the focus search can be reduced.

Description

Mini Searchlight Unit for Disc Player

1 is a structural diagram of a disc used in a mini disc player.

2 is a diagram showing the amount of light picked up and the focus 0.K signal during focus search;

3 is a block diagram showing a focus search apparatus of a conventional mini disc player.

4 is a block diagram showing a focus search apparatus of a mini disc player according to the present invention.

FIG. 5 is a detailed block diagram of the counter unit shown in FIG.

* Explanation of symbols for main parts of the drawings

400: disc 410: optical pickup

420: I-V conversion unit 430: comparison unit

440: counter portion 442: edge detector

444: quaternary counter 446: AND gate

450: microcomputer 460: focus control unit

The present invention relates to a mini disk player (MDP, hereinafter abbreviated as MDP), and in particular, an MDP focus search apparatus capable of smoothly performing a search without failing to accurately read data recorded in the MD in the MDP. It is about.

In general, MDP has been developed to overcome the disadvantages of not being able to record digitally recorded voice signals and weaknesses of compact disc players (CDP, hereinafter referred to as CDP). The device is expanding its market.

The MD uses a digital method with excellent sound quality and compression technology that can record the same amount of music as a CD, even though it is about half the size of a CD (64mm). In addition, high-speed random access and various repetitive playback is possible, so that the sound is not broken by the vibration is stored in the cartridge and easy to carry.

On the other hand, the recording medium of MD includes a reproduction-only disc having the same structure as a conventional CD and a magneto-optical disc capable of recording external audio signals.

FIG. 1 is a schematic view showing the structure of a general recordable disc used in an MD, and is composed of a protective coating film 10, an aluminum reflecting film 20, a magnetic film 30, and a substrate 40. As shown in FIG.

In the figure, reference numeral 50 denotes the uppermost position of the objective lens, reference numeral 60 denotes the normal position of the objective lens, and reference numeral 70 denotes the lowest position of the objective lens.

Unlike the CD, the MD detects whether the objective is in focus while descending from the top position for the following reasons.

In general, a focus O.K signal indicating that focus is achieved is generated by identifying that the amount of light reflected from the disk is greater than and less than the reference value.

2 is a view showing the amount of light reflected from the disk and the focus O.K signal accordingly when the objective lens, that is, the optical pickup unit ascends from the lowest position to the highest position and then descends again.

In the figure, a focused O.K signal is generated by converting the detected light, that is, the detected light amount into an electrical signal, and then binarizing the signal around a reference voltage.

The left and right small focus O.K signals C and D are unwanted signals generated by the weak signal reflected from the magnetic film 30.

Therefore, if the focus search operation in the MD is performed while raising the objective lens from the lowest position to the highest position as in the CD, the focus servo is operated at the 'c' portion, so that the magnetic film 30 is used instead of the aluminum reflective film 20. Since the light is focused, normal operation cannot be performed.

Therefore, in the MD, the focus search operation is performed when the objective lens is lowered from the highest position to the lowest position. That is, the focus search may be performed on the aluminum reflective film 20 in the focus search signals 'A' and 'B', but in the MD, the focus search is performed by the light reflected from B. FIG.

However, the sections of the focus O.K signal 'A' and the focus O.K signal 'B' are different from each other. That is, the section 'A' is wider than the section 'B' because the driving system for driving the objective lens in the situation of the same gravity acts as the force increases in 'A' and in the direction of 'B' in the downward direction. to be.

3 is a block diagram showing a conventional MDP focus search apparatus, which includes a disk 300, an optical pickup unit 310, an IV converter 320, a comparator 330, a microcomputer 340, and a focus controller 350. It is composed of

In the same figure, the optical pickup unit 310 picks up the light reflected from the disk 300 while lowering the objective lens (not shown) from the highest position to the lowest position, and converts the light into an electrical signal, that is, a current signal, and outputs it. do.

The I-V converter 320 converts and amplifies a current signal input from the optical pickup unit 310 into a voltage signal and outputs the voltage signal to the comparator 330.

The comparator 330 compares the voltage signal provided from the I-V converter 320 with a preset reference voltage and generates a focus O.K signal when it is larger than the reference voltage.

When the focus O.K signal is provided from the comparator 330, the microcomputer 340 generates a control signal according to the focus controller 350.

The focus controller 350 generates the focus search and the focus servo signal to the optical pickup unit 310 according to the control signal of the microcomputer 340 to perform the focus control.

Therefore, when the focus search is executed, the focus search operation is more likely to fail because the drive system for driving the objective lens applies the force to the objective lens in the upward or downward direction in the same gravity as described above. In addition, it must be taken into account that the time margin of the focus search operation in the design is shorter than that performed when the objective lens is raised.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, which prevents the focus search failure when attempting the focus search of the MDP, reduces the focus search operation time, and executes the focus search in the same manner as the CD. The purpose of the present invention is to provide a focus search apparatus of an MDP.

According to a preferred embodiment of the present invention for achieving the above object, in the focus search device of the MDP: an optical pickup unit for picking up the light reflected from the disk and converting it into a current signal, provided from the optical pickup unit An IV converter for converting the current signal into a voltage signal and amplifying and outputting the amplified signal to a predetermined magnitude, and comparing the voltage signal provided from the IV converter with a preset reference signal and comparing the voltage signal with a predetermined reference signal. A comparator for generating a signal; a counter part for counting a comparison signal provided from the comparator, and generating a focus OK signal when the count value is 2; and generating a control signal according to the focus OK signal provided from the counter part. And a microcomputer for outputting a clock signal for resetting the counter unit to the counter unit. And a focus control unit for providing a focus search and a focus servo signal to the optical pickup unit according to a control signal provided from the com.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram showing a focus search apparatus of an MDP according to the present invention, and includes a disk 400, an optical pickup unit 410, an IV converter 420, a comparator 430, a counter unit 440, and a microcomputer ( 450, and a focus control unit 460.

In the figure, the optical pickup unit 410 detects the light reflected from the disk 400, converts it into an electrical signal, that is, a current signal, and provides the converted signal to the I-V converter 420.

The I-V converter 420 converts the current signal provided from the optical pickup unit 410 into a voltage signal, amplifies the weak voltage signal to a predetermined magnitude, and provides the converted signal to the comparator 430.

The comparator 430 compares the voltage signal amplified to a predetermined magnitude provided from the IV converter 420 with a preset reference signal, and if the voltage signal is larger than the preset reference signal, the comparison signal is sent to the counter 440. to provide.

The counter unit 440 counts the comparison signal provided from the comparison unit 430. In addition, when the counted value reaches 2, the counter unit 440 outputs a focus O.K signal to the microcomputer 450 indicating that the focus search is performed.

5 is a detailed block diagram of the counter unit 440, and includes an edge detector 442, a quaternary counter 444, and an AND gate 446. As shown in FIG.

In the figure, the microcomputer 450 provides a clock signal for resetting, that is, initializing, the counter unit 440 to the quadrature counter 444 in the counter unit 440.

The edge detector 442 detects the edge of the comparison signal provided from the comparator 430 and outputs a clock signal accordingly.

The quaternary counter 444 counters the output signal of the edge detector 442 and generates respective output signals Q1 and Q2.

The AND gate 446 ANDs the output signals Q1 and Q2 of the ternary counter 444 to provide the focus O.K signal to the microcomputer 450. In this case, the above AND operation means an AND operation.

The microcomputer 450 generates a control signal according to the focus O.K signal to the focus controller 460.

The focus controller 460 provides the focus search and the focus servo signal according to the control signal provided from the microcomputer 450 to the optical pickup unit 410 to perform the focus search.

On the other hand, the focus search is made while the objective lens (not shown) of the optical pickup section 410 is raised from the lowest position to the highest position.

Therefore, the present invention can perform the focus search in the same way as the CD in the MD. In addition, there is an advantage that can prevent the failure of the focus search and reduce the operating time of the focus search.

While the invention has been shown and described with reference to certain preferred embodiments, those skilled in the art will recognize that various modifications and changes can occur without departing from the spirit and scope of the invention as set forth in the claims below.

Claims (1)

An optical pickup unit for picking up the light reflected from a predetermined disk and converting the light into a current signal; an IV converter for converting the current signal provided from the optical pickup unit into a voltage signal and amplifying and outputting the voltage signal to a predetermined size; Comparing the voltage signal provided from the unit with a predetermined reference signal and the voltage signal is greater than the reference signal, the comparison unit for generating a comparison signal according to this, the comparison signal provided from the comparison unit is counted and the count value is 2 A counter signal for generating a focus OK signal, a clock signal for resetting the counter part to the counter part, and a control signal provided from the microcomputer and a microcomputer for generating a control signal according to the focus OK signal provided from the counter part. To provide a focus search and focus servo signal to the optical pickup. In the focus search unit of the mini-disk player comprising a focus control: the counter unit to the edge detector output to detect the edge of the comparison signal output unit; A quadrature counter that is reset by receiving the clock signal provided from the microcomputer and counts the output signal of the edge detector and outputs the count value; And an AND gate for outputting a focus O.K signal by performing an AND operation on the output signal of the binary counter.