JPH0830943A - Tracking controller - Google Patents

Abstract

PURPOSE:To prevent erroneous judgement of a pulse height value and to prevent the deterioration in reproducing picture quality by increasing B number of times of pulse height value level extraction even when the fluctuation in a pulse height value level occurs, calculating a mean value and absorbing the fluctuation in the pulse height value level. CONSTITUTION:The pulse height value level obtained by a pulse height value detection circuit is stored in a memory 8 by a pulse height value level extraction number of times integration circuit 7. Then, and further, the operation are performed by the number of optionally setting times (A times: A>=2) while fixing a step value, and integrated values by A times 3 obtained in the memory 8 successively. A mean value calculation circuit 9 reads in a pulse height value level integrated value from the memory 8, and the integrated value is divided by the setting times A, and a mean value is calculated, and the pulse height value level absorbing the fluctuation is obtained. Then, thereafter, the operation is performed successively moving only by a tracking movement amount decided as one 3P, and a control signal output circuit 10 issues a command to a phase control circuit 11 so that the calculated means value becomes a maximum value to control a capstan motor 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus using a magnetic tape.

[0002]

2. Description of the Related Art As a conventional technique, for example, as described in "Radio Technology" issued by Radio Engineering Co., Ltd., February 1989, pages 167 to 170, and October 1989, the pages 165 to 167. As a method of performing auto-tracking, by changing the delay amount (the amount by which the position of the video or audio playback head is delayed relative to the tracking control reference position recorded on the tape), the peak value level is tracked to determine the maximum value. The method of detecting the value is used.

[0003]

However, the actual crest value level constantly fluctuates between large and small at the time of observing the crest value level at each step value due to the influence of mechanical system wow and flutter. Specifically, as shown in FIGS. 1 and 2, the FM recording signal read from the magnetic tape 3 by the video reproducing head 1 or the audio reproducing head 2 is
As shown in (1), the amplitude fluctuates over the range of Δa with respect to the normal amplitude 2a due to the above influence, and when amplified by the preamplification circuit 4, it becomes as shown in (2) (2a-> 2b). , Δ
a-> Δb), and when this is DC converted by the peak value detection circuit 5, it becomes as shown in (3). That is, as a result, the peak value b changes over a range of Δb. In the conventional technique, a processing method that takes this effect into consideration has not been considered.

Therefore, when the magnetic tape is reproduced, the peak value level fluctuates, so that it is not always possible to retrieve the accurate peak value level even if the auto-tracking operation is normal. There is a problem that the locus and the locus of the head at the time of reproduction may be slightly deviated from each other, resulting in deterioration of reproduced image quality.

An object of the present invention is to improve the reproduced image quality by absorbing the fluctuation amount of the peak value level by calculating the average value of the varying peak value level at each step value. .

[0006]

In order to achieve the above-mentioned object, the algorithm of the auto-tracking software section used in the system control microcomputer says, "In each step value, each step value remains fixed. The operation of "repeating the peak value level extraction operation within a set fixed time for each step and accumulating the peak value levels at any time to obtain the integrated value" was performed A times to obtain the integrated values. The above problem is solved by newly adding the operation of calculating the average value based on the integrated value of the peak value level of A times at each step value, and absorbing the fluctuation of the peak value level.

[0007]

By absorbing the fluctuation of the varying peak value level, the head can accurately trace the trace of the recorded signal, so that the deterioration of the reproduced image quality can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1, 2, 3 and 4 by taking a video tape recorder (hereinafter abbreviated as VTR) as an example. FIG. 1 is an FM signal detection block diagram showing an embodiment of the present invention, FIG. 2 is an FM signal detection process waveform, and FIG.
Is a system control block diagram showing an embodiment of the present invention, and FIG. 4 is a detected waveform. 1 is a video playback head,
2 is an audio (HiFi) reproducing head, 3 is a magnetic tape, 4 is a preamplifier circuit, 5 is a crest value detection circuit, 6 is a system control microcomputer system, 7 is a crest value level extraction frequency integration circuit, 8 is a memory, 9 Is an average value calculation circuit, 10
Is a control signal output circuit, 11 is a capstan motor phase control circuit, and 12 is a capstan motor.

First, referring to FIG. 1, FM recording signals from the magnetic tape 3 to the video reproducing head 1 or the audio reproducing head 2 are shown in FIG. (1) is read and input to the preamplifier circuit 4. The input FM signal is amplified by this preamplifier circuit 4 and shown in FIG. (2), which is input to the peak value detection circuit 5. Then, the peak value detection circuit 5 detects the peak value from the FM signal and performs DC conversion, and FIG. As in (3), the peak value level at that step value is obtained. The obtained peak value level is input to the system control microcomputer system 6, and thereafter the peak value level extraction number integration circuit 7 stores the level in the memory 8. Thereafter, the crest value level extracting operation within a preset time is repeated, and the crest value level is accumulated in the memory 8 at any time. Then, while the step value is fixed, the above-mentioned operation is performed an arbitrary set number of times (A times: but A ≧ 2 times) to successively accumulate the peak value level in the memory 8 and finally obtain the integrated value for A times. . When the final integrated value is obtained, the average value calculating circuit 9 reads the peak value level integrated value from the memory 8 and divides the integrated value by an arbitrary set number of times (A times: however, A ≧ 2 times). Figure 4 shows the average value calculated. As in (2), the peak value level that absorbs the fluctuation is obtained. After that, the control signal output circuit 10 is changed to the capstan motor phase control circuit 11 so that the above-mentioned operation is performed by sequentially shifting by the tracking movement amount determined as one step, and the calculated average value takes the maximum value. It outputs a command and controls the capstan motor 12.

In this way, by absorbing the fluctuation of the peak value level and taking the average value thereof, the tracking is adjusted so that the head accurately traces the track recorded by the auto-tracking operation.

[0011]

As described above, according to the present invention, when the magnetic tape is reproduced, even if the peak value level changes due to mechanical wow and flutter, etc., the peak value level extraction number is increased and the average value is increased. By calculating the value and absorbing the fluctuation amount of the peak value level, it is possible to prevent the erroneous judgment of the peak value level of the auto tracking system and prevent the deterioration of the reproduced image quality due to the tracking error.

[Brief description of drawings]

FIG. 1 is an FM signal detection block diagram.

FIG. 2 is a waveform diagram of an FM signal detection process.

FIG. 3 is a system control block diagram.

FIG. 4 is a detection waveform diagram.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Video reproducing head, 2 ... Audio (HiFi) reproducing head, 3 ... Magnetic tape, 4 ... Preamplifier circuit, 5 ... Crest value detection circuit, 6 ... System control microcomputer system,
7 ... Crest value level extraction number integration circuit, 8 ... Memory, 9
... Average value calculation circuit, 10 ... Control signal output circuit, 11 ... Capstan motor phase control circuit, 12 ... Capstan motor.

Claims (1)

[Claims] 1. In a magnetic recording / reproducing apparatus for obtaining a signal by tracing a signal recorded on the magnetic tape by reproducing the magnetic tape with a magnetic head, the magnetic head is placed on the left and right sides of a signal track recorded on the magnetic tape. Is equipped with a means for moving in small variable units (hereinafter referred to as "steps") and a detection circuit for detecting the peak value level of the signal at each step value. In a tracking control device for matching head traces, each step value is fixed for a certain set time and the above-mentioned peak value level detection operation is performed an arbitrary set number of times (A times: but A ≧ 2 times). After obtaining the integrated value, the average value of the peak value level is calculated based on the obtained peak value level integrated value of A times, and the auto tracking operation is performed based on this value to perform the magnetic head. Tracking control device, characterized in that match the best position of the signal track.