JPH061599B2 - Recording position setting device - Google Patents

Description

The present invention relates to a recording position setting device for magnetically recording or reproducing stereo recording, reproduction, karaoke recording, reproduction, etc. by a rotary head.

[Conventional technology]

Conventionally, in a helical scan type magnetic recording apparatus using a rotary head, a tape 16 is fed at a constant speed, and a rotary cylinder 19 having four heads 17, 17, 18 and 18 for recording / reproducing at 90 ° intervals has a rotary drum 20. Are driving through. The recording position timing of the recording / playback heads 17, 17, 18, 18 for the tape is set by the PG for detecting the magnetism of the magnet 21 attached to the rotary drum 20 as shown in FIG. The PG pulse A is generated by the head 22 (the head of the pulse generator) to obtain the relative position information of the drum 20 with respect to the tape 16, and the heads 17 and 1 for actual recording and reproduction are obtained for the information.
7, 18 and 18 determine the delay with respect to the PG detection timing. Reference numeral 23 is a drive belt. FIG. 2 (a) shows a model in which two PG pulses are generated every 180 ° during one rotation of the drum, and the winding angle of the tape is 90 °, but it is not limited to this. .

FIG. 3 shows the configuration of a conventional delay circuit. 1 is PG
A detector for an output pulse A of the head, 2 is an analog delay circuit for setting a signal B having a delay time α with respect to the rise of this PG pulse, and 3 is an output terminal of a recording timing output C.

Assuming that the delay time to the actual recording position with respect to the rising of the PG pulse A is α, this delay time α can be set by a variable capacitor C ₁ , a variable resistor R _1, etc. as shown in FIG. It is generally set by an analog delay element such as a vibrator. The timing at this time is the second
It is shown in Figure (b). In FIG. 2B, A is a PG pulse,
B shows the timing output of the delay circuit, and C shows the actual recording timing output.

[Problems to be solved by the invention]

In this conventional analog delay circuit 2, since the delay time α is set by the variable capacitor C ₁ or the variable resistor R ₁ , the accuracy is inevitably reduced as the actual delay time α is increased. I don't get. Also, due to variations in the mounting positions of the recording and playback heads on the rotary drum 20, adjustment is required for each rotary drum 20, which causes a setting error at the time of adjustment, resulting in a variation of several μsec to several tens of μsec in total. Become. Therefore, in the case of PCM recording or the like that requires high recording density, as the variation error of the delay time α increases, a large area is required as a margin area between the data area and other areas. Therefore, the number of bits of information and data tends to decrease with respect to the total number of recording bits. In addition, this fluctuation causes a fluctuation in the recording position between adjacent tracks, which has a great effect on the setting of a system such as an ATF (Automatic Tracking Finding System) that performs tracking by detecting leak output from the adjacent tracks. It will be.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a system capable of minimizing the fluctuation error of the recording position timing.

[Means for solving problems]

The present invention detects, in a helical scan type magnetic recording device, recording or reproducing heads 17 and 18 attached to a rotary drum 20, a PG head 22 representing the relative position of the heads, and a PG pulse A thereof. The detector 1 and the heads 17 and 18 for recording or reproducing by the PG pulse A thereof
Has a delay time α counter 5 for measuring the timing of the reference position to be written in the recording medium 16.

[Action]

The value of the α counter 5, that is, the timing output B sets the recording timing output C for outputting the recording data.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.
In the figure, 1 is a PG pulse detector, 2a is a digital delay circuit, 5 is its digital α counter, 4 is a setting device for supplying a preset value of this counter, and 6 is this crystal oscillator. Clock pulse CK from crystal oscillator 6
₀ is input to the frequency divider 10, becomes a clock pulse CK having an appropriate frequency, and is supplied to the CK input terminal 9 of the α counter 5. The preset value of the α counter 5 is corrected by the preset setter 4 to the number of clock pulses CK corresponding to the delay time α measured in advance and supplied to the preset input terminal 7.

Next, the operation of this device will be described.

The PG pulse A from the PG pulse detector 1 is input to the terminal 8 for initialization of the α counter 5. As a result, the contents of the α counter 5 are initialized (reduced to zero) at the rising of the input PG pulse A, and the output of the α counter 5 becomes low as shown by the timing output B in FIG. Next, from the frequency divider 10 to the input terminal 9 of the α counter 5.
The clock pulse CK is supplied to and counts up at any time. The timing output B becomes high when the number of inputs of the clock pulse CK reaches a preset value, that is, the number of counts equal to the delay time α.

By setting the recording timing output C in this way, the higher the frequency of the clock pulse CK input to the α counter 5, the higher the accuracy of setting the delay time α becomes possible. Further, even when the delay time α is measured in advance, the adjustment error can be minimized by using such a counter. Therefore, the delay time α from the rise of the PG pulse shown in FIG. 2B to the actual recording position can be measured with high accuracy.

〔effect〕

As described above, according to the present invention, by using the digital delay method using the counter when setting the delay time α from the PG pulse to the recording position, it is possible to set the recording position with high accuracy with a relatively simple hardware configuration. It is possible to reduce the margin area between the data area and the other area. Also, in the case of a system such as ATF, an excellent effect that the configuration can be performed in a smaller area can be expected.

[Brief description of drawings]

FIG. 1 is a diagram showing a recording position setting circuit of an embodiment of the present invention, FIG. 2 (a) is a perspective view showing the outline of the magnetic recording apparatus, FIG. 2 (b) is its timing chart, and FIG. The figure shows a conventional setting circuit. 20 …… Rotating drum, 17,18 …… Recording / playback head, 2
2 ... PG head, A ... PG pulse, 1 ... detector, 1
6 …… Recording medium, 5 …… α counter, C …… Recording timing output.

Claims (1)

[Claims] 1. A helical scan type magnetic recording device, comprising: a recording or reproducing head attached to a rotating drum; a PG head indicating a relative position of the head; and a detector for detecting the PG pulse. Α of the delay time α for measuring the timing of the reference position where the recording or reproducing head should write on the recording medium by the PG pulse
A recording position setting device having a counter and setting a recording timing output for outputting recording data according to the value of the α counter.