JPS6027472B2 - Still image playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a still image reproducing apparatus for reproducing a recording medium on which a digitized color still image signal is recorded.

2. Description of the Related Art Conventionally, one field or one frame of still image signal is extracted from a color television signal, and this is processed by A/
A still image recording and reproducing apparatus is known that converts the signal into D and records it on a magnetic sheet or the like, and also reproduces the recorded signal.

In this device, when A/D converting a color still image signal, the subcarrier frequency fs is multiplied by n (n: 2,
Sampling is performed using a clock pulse with a frequency nfs of 3......). Further, during reproduction, the signal reproduced by the reproduction head is once written into the memory and then read out, and the read signal is subjected to D/A conversion. The clock pulse for reading the above-mentioned 〆Moli-1 is
The frequency of a clock pulse of frequency fs obtained from a clock pulse generator built into the device is multiplied by n. Problems to be Solved by the Invention In the above-mentioned still image reproduction device, there are variations in the phase of the clock pulse obtained from the clock pulse generator depending on the individual device or model.
For this reason, there is a problem in that color shift occurs on the playback screen.

Means for Solving the Problems In the present invention, the phase of the burst signal included in the output signal of the D/A converter matches the reference phase.
The phase of the read clock pulse of the closing moly is controlled.

In the embodiment diagram, a digital color still image signal sampled at a frequency of 4 fs, for example, is recorded on the magnetic sheet 6.

This still image signal is reproduced by a reproducing head 8 and read out from the memory 7 using a clock pulse of a frequency equal to or higher than that of a clock pulse. That is,
The clock pulse obtained from the clock pulse generator 9 is passed through the phase modulator 10 to the multiplier circuit 11 at a frequency of 4fs.
This clock pulse is supplied to the memory 7 as a read clock pulse. A portion of the clock pulses obtained from the clock pulse generator 9 are also applied to one terminal of the phase comparator 12. The signal read from the memory 7 is converted into an analog signal by the D/A converter 13 and taken out from the output terminal 14.

The color burst signal contained in this output signal is extracted by a burst signal detector 15 and applied to the other input terminal of the phase comparator 12. Along with this, the detection signal obtained from the burst signal detector 15 causes the switch circuit 16 to
is closed. In the phase comparator 12, the clock pulse from the clock pulse generator 9 and the burst signal included in the output signal are compared in phase. A comparison output corresponding to the phase difference between the two controls the phase modulator 10 through the switch circuit 16 and the hold circuit 17. Then, every time the burst signal of the output signal is detected by the detection circuit 15, the same operation as described above is performed to hold the phase of the burst signal. The phase modulator 10 is controlled according to this held phase. As a result, the phase of the clock pulse obtained from the phase modulator 10 matches the phase of the burst signal included in the output signal. The memory 7 is read out using a clock pulse obtained by multiplying the frequency of this phase-locked clock pulse by four in the multiplier circuit 11. According to the above, since the phase of the read clock pulse of the memory 7 is controlled so that the phase of the burst signal included in the output signal matches the reference phase, color shift is prevented regardless of variations in the clock pulse generator 9. I never wake up. Effects of the Invention The present invention changes the phase of the memory read clock pulse by
Since the phase of the burst signal included in the D/A converted signal is controlled to match the reference phase, there will be no color shift on the playback screen regardless of variations in the clock pulse generator built into each device. can be prevented from occurring.

[Brief explanation of the drawing]

The drawing is a block diagram showing an embodiment of the invention. In addition, in the symbols used in the drawings, 6...
・Magnetic sheet, 7...Memory, 8...
・Playback head, 9...Clock pulse generator,
10... Phase modulator, 12... Phase comparator, 13... D/A converter. Figure [ Shigeru

Claims (1)

[Claims] 1. In a still image reproducing device that reproduces a recording medium on which a digitized color still image signal is recorded, writes this reproduced signal in a memory, reads it out, and performs D/A conversion on the read signal. . A still image reproducing device characterized in that the phase of the read clock pulse of the memory is controlled so that the phase of the burst signal included in the D/A converted signal coincides with a reference phase.