JPS59144289A - Still picture signal reproducing device - Google Patents

Abstract

PURPOSE:To simplify the constitution of a reproducing device for a disk, etc., and to increase storage capacity by making the rotation of the disk constant, storing one-screen data in a memory temporarily, and reproducing a still picture by a suitable clock. CONSTITUTION:This reproducing device consists of a driving means 2 which rotates the optical disk 1, etc., at a constant rotating speed, a pickup 4 which reads a signal out of the disk 1, etc., the memory 11 wherein the output of the pickup 4 is stored temporarily, a demodulating means 17 which demodulates and outputs the output of the memoryf 11 to an output device, a timing signal detecting circuit 6 which detects the timing signal in the output of the pickup 4, a memory controller 9 which stores one-screen data on a still picture signal in the memory in responding to the output of the circuit 6 and then outputs it to the timing means 17 at timing matching with the output device, etc. Consequently, the constitution is simplified, high-speed access is realized, and the recording capacity is increased.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a reproducing device for an optical disk, a magneto-optical disk, a magnetic disk, etc., in which a still image signal modulated in 9 modes is recorded on a spiral or concentric recording track. The present invention relates to a playback device that plays back a disk-shaped recording medium (hereinafter simply referred to as a disk) that has been digitally recorded at a uniform recording density while rotating it at a constant rotational speed.

(Background of the Invention) Conventionally, the methods for digitally recording onto a disc include the constant angular velocity method (hereinafter referred to as the CAV method) and the constant serpentine method (hereinafter referred to as the CAV method).
(referred to as the LV method) is known.

Unlike the CLV system, the CAV system does not require a device for variable control of the rotational speed of the disc, but the recording/reproducing system is simpler. Also, it has the advantage that the access time excluding playback is short, but the recording density decreases as you go outside the disc, so the recording capacity of the entire disc is CLV.
It has the disadvantage that it is smaller than the conventional method.

On the other hand, the CLV method has a larger recording capacity than the CAV method because there is no difference in recording density between the inner and outer peripheries of the disk, but since the rotation speed of the disk, which has a large inertial mass, must be controlled according to the radius of the disk, the recording and reproducing device Both are complicated and expensive. Another disadvantage is that the access time during playback becomes long.

Therefore, an optical disk device that has the advantages of both types, that is, a still image optical disk device that allows high-speed access and has a large storage capacity, has been proposed. For example, the tracks of an optical disk are divided into a plurality of groups depending on the distance from the center of rotation, and within each group, the CAV method is used, and between the groups, the CLV method is used in stages. However, with this method, a variable rotation speed control device is still required for the recording and playback image device, and in the end, the CLV method is sufficient for accessing widely separated groups, such as accessing from the innermost circumference to the outermost circumference. The disadvantage is that it requires an access time of .

(Object of the Invention) The purpose of the present invention is to solve these drawbacks and provide a still image signal reproducing device that has both the simple configuration and high-speed access function of the CAV method and the large recording capacity (high recording density) of the CLV method. do.

(Summary of the Invention) In order to achieve the above object, the present invention rotates a disk at a constant speed, stores one screen worth of reproduced still image signals in a temporary memory, and uses a clock suitable for various output devices such as television sets and printers. By reading out the reproduced still image signal from the memory, the still image signal has a normal time axis, and the still image is reproduced using the still image signal.

Here, when pits are formed at the same recording density on all tracks as in the CLV method, when pits are formed at a frequency f of 2πri ni on a disk rotating at a rotation speed ni at a disk radius ri, f= 2°, and from this the length d of the pit is expressed by equation (1).

πri nl d= f ・・・・・・・・・・・・(1) Here, the recording density is constant in all tracks, which means that if the same frequency is recorded, the pit length d is It is true that it is constant regardless of the radius, so it is necessary to keep the product r i - n i of the disk radius and the number of rotations constant.

That is, the rotation speed ni is controlled according to changes in the disk radius ri to keep the product ri-ni constant. Next, let us consider reproducing the bit length d formed in this manner using constant speed rotation, that is, the CAV method.

Rotating at a constant rotation speed N, the frequency %F obtained by the pit length d on the disk radius r is F = (1) and (2)
Substituting into the expression (3) is obtained.

F = 4 bif (6) tnt Equation (6) is the frequency iF obtained when a signal with a frequency f recorded by the CLV method is reproduced at a constant rotation speed N1 and a disk radius r. It shows. Here, ri-ni is an arbitrarily determined constant, and is the highest frequency fm of the signal to be recorded.
Its value is determined by the size of the bit length d of ax on the disk. For example fmax=
If it is 5MH2 and d='1μm, ri
・ni=1500trtm/-ec. In this case, if ri=50mm, ni is 1.80 Orp
m (30 rps). Further, N is also a constant arbitrarily determined. When playing, CAV method ← constant rotation speed N
), the frequency F is reproduced. A signal of frequency f is reproduced by inversely transforming (f-1p10) this using equation (6).The present invention is based on the above-mentioned principle.

(Example) An example in which the present invention is applied to an optical disk still image recording and reproducing device will be described below with reference to FIGS. 1 and 2. 1st
In the figure, an optical disk 1 is rotated by a spindle motor 2 at a constant rotation speed N, and the rotation speed N is expressed by a pulse generator 3.
Measured by.

The optical pink-up 4 is moved in the disk radial direction by a slider, and its position r is measured by a linear scale 5.

7 is an arithmetic circuit that converts the frequency of data according to the above equation (6) using the radius r and the rotation speed N;
It outputs a voltage or digital value according to the voltage, and is configured by hardware or software. 15 is a variable frequency pulse generation circuit whose pulse output frequency changes depending on the input value; when the output of the arithmetic circuit 7 is a voltage, it is a VCO (voltage control onator);
Further, when the output of the arithmetic circuit 7 is a digital value, PD(
programmable divider).

The timing signal detection circuit 6 extracts a timing signal from the signal reproduced by the optical head 4 and generates a timing pulse.

The clock generation circuit 8 divides the frequency of the pulse from the timing signal detection circuit 6 or the variable frequency pulse generation circuit 15 by switching the switch 18, and generates a clock.

The output device clock generation circuit 10 generates a clock suitable for the output device 14.

The memory control circuit 9 controls input/output switching of the memory, supply of a clock to the memory, refreshing of the memory, and the like. A clock to the memory control circuit 9 is supplied from the clock generation circuit 8 or the clock generation circuit 10, and the selection thereof is made by the switch 2. The memory 11 has a capacity for one still image, and is composed of dynamic RAM or static RAM. The output of the memory 11 is configured to be connectable to either the laser diode drive circuit 12 or the demodulation circuit 17 by a switch 21. The input device 1 is a TV camera or a still image reading device using a linear sensor array (for example, an input section of a facsimile), and its output is digital.

The modulation circuit 16 performs digital modulation (for example, MFM) suitable for recording on an optical disk device, and also generates an error correction signal and a timing signal based on the timing pulse from the timing pulse generator 25 in order to reproduce signals from the optical disk without errors. It is an addition. 22 is at the time of recording,
This is a switch that can be changed depending on the time of playback. The demodulation circuit 17 demodulates the digitally modulated signal into a signal that can be input to the output device 14.

The output device 14 is a CRT or a printer. The laser drive circuit 12 drives a laser diode (LD) according to the output of the memory 11 and modulates the intensity of the laser beam.

The operation of the optical disk device configured as above will be described below. First, the recording mode will be explained. Switches are the first
Connect as shown in the solid line in the figure. That is, switch 22 is moved to the 16 side, switch 21 is moved to the 12 side, switch 18 is moved to the 15 side,
Connect the switches 23 to the 8 sides. The still image is converted into an electrical signal by the input device 13 and inputted to the modulation circuit 16 as a digital signal. The signal is digitally modulated by the modulation circuit 16, and a timing signal etc. are added based on the timing pulse of frequency f1. FIG. 2(a) shows the modulation circuit 16
This is the output of 24 is a timing signal, and 20 is an image signal including an imposed correction signal.

In order to distinguish the timing signal 24 from the signal 20, for example, a signal consisting of a certain number of consecutive pulses with a certain duty ratio is defined as a timing signal (of course, the frequency of the timing signal 24 is f), and this is stored in the memory 11. do.

Move the optical head to the position to record. The position is read by the linear scale 5. Since the disk rotation speed N and riXni are constants as described above, the above formula (6
) can be used to find F. When the arithmetic circuit 7 outputs a voltage corresponding to F, this output is input to the variable frequency pulse generation circuit 15, which generates a pulse having a frequency of F. A clock generation circuit 8 divides the frequency F to obtain a clock having a frequency nF. The laser beam is outputted from the memory 11 with a clock of frequency nF, and the intensity of the laser beam is modulated by the laser drive circuit 12 to form bits on the optical disk 1, and recording is completed.

Next, the playback mode will be explained. Playback switch 18
．． 21 and 22 are connected to the side indicated by the dotted line in FIG.

The signal reproduced by the optical pickup is as shown in FIG. 2(a) when read out at the disk radius r. The frequency of the timing signal 24 is F. The timing signal detection circuit 6 detects the timing signal 24 from the signal shown in FIG. 2(a).
is extracted and converted into a timing pulse 19 as shown in FIG. 2(b). The timing pulse 19 is input to the clock generation circuit 8 via the switch 18. The clock generating circuit 8 performs branching and outputs the nF clock shown in FIG. 2(C). Clock frequency nF
The signal of the optical pickup 4 is stored in the memory 11.

Next, the switch 23 is switched to the output device clock generation circuit 10 side to generate a clock of frequency nf. Here, the switching of the switch 26 is controlled so that after one screen's worth of image signals is stored in the memory 11, the clock generation circuit 8 is switched to the clock generation circuit 10 for the output device. The fact that one screen worth of image signals has been stored in the memory 11 can be known by various known means. For example, this can be known by storing a signal at a specific address in the memory 11, or by recording a specific signal at the end of one screen in advance and detecting this. An image signal is output from the memory 11 at a clock frequency nf and input to the demodulation circuit 17. The demodulation circuit 17 demodulates the output device 1 into a signal that can operate the output device 14.
4 to obtain a reproduced image.

In this embodiment, both recording and reproduction were carried out at a constant disk rotational speed, but of course a disk recorded by the conventional CLV method can be reproduced in exactly the same manner.

In the embodiment shown in FIG. 1, the position r of the optical pickup was determined using a linear scale 5. However, when using an optical disc with a guide track, it is not necessary to use the linear scale 5. This is because the track pitch of the disk is kept constant, so if the track address is known, its position can be calculated by, for example, a microcomputer. Further, the variable frequency pulse generation circuit 15 may be constructed of a plurality of circuits having different oscillation frequency ranges, and the circuit to be used may be selected according to the frequency F.

Further, in the embodiment, the timing signal 24 is added at the time of modulation, but it is possible to use a modulation method that allows self-clock (for example, MP'M:
quencyModulation, PE:Phas
e encoding, etc.), there is no need to add the timing signal 24.

(Effects of the Invention) As described above, according to the present invention, the disk drive is performed using ff11.
Because it rotates, it has a simple structure and allows high-speed access, and can be used as a recording medium over all recording tracks recorded on a disk with a large recording capacity, such as the conventional CLV method or the method shown in this example. A disk with a constant recording density can be used.

[Brief explanation of drawings]

FIG. 1 shows an optical disk still image recording and reproducing apparatus to which a reproducing apparatus according to the present invention is applied, and FIG. 2 is a diagram of signal waveforms at various points in FIG. 1. Applicant Nippon Kogaku Co., Ltd. Agent Takao Watanabe

Claims (1)

[Claims] In a playback device that rotates and plays back a disk-shaped recording medium on which a modulated still image signal is digitally recorded on a spiral or concentric recording track with uniform recording density, the recording medium is rotated at a constant speed. a pickup for reading out signals from the recording tracks; and a storage capacity i1 for one screen, into which the output of the pickup is input.
': a memory means having: a demodulating means for outputting the output of the memory means to an output device; a timing (U amount detecting means) for detecting a timing signal included in the output of the pickup; A memory controlling the memory means to store one screen of the still image signal in accordance with the output of the timing detecting means, and then outputting the stored still image signal to the demodulating means at a timing suitable for the output device. 1. A still image signal reproducing device, comprising: a control means.