JP2650548B2 - Auto calibration device for recording signal level - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder, and more particularly to an auto-calibration system for automatically adjusting a recording signal level (or recording level) for a magnetic tape (hereinafter simply referred to as "tape") to an optimum value. The improvement of the application device.

[0002]

2. Description of the Related Art As a prior art for performing auto-calibration in a video tape recorder, Japanese Patent Laid-Open No.
Japanese Unexamined Patent Publication No. 234402/1990. According to this conventional technique, a signal whose level changes stepwise is recorded on a tape. Then, the recording signal is reproduced to detect a portion having the maximum value, and the signal level at the time of recording corresponding to the maximum value is set as the optimum recording current.

[0003]

However, such a conventional technique has the following disadvantages. (1) Signal recording for calibration is for one field (one track). On the other hand, at the entrance and exit of signal recording, that is, at the beginning and end of the track, the degree of tape contact with the head is different from that at the center. For this reason, the read signal level changes between the first and last portions and the center portion of the read signal, and the head is susceptible to influences.

(2) In addition, since the signal recording is as short as one field, it is easily affected by dropout on the tape side. (3) Further, in the so-called VHS system (registered trademark), a deep recording system in which an audio signal is recorded in a deep part of a tape is adopted. For this reason, in the method of setting the optimum recording signal level by recording and reproducing only the video signal as in the above-described conventional technique, there is a possibility that the reproduction characteristics of the audio signal may be deteriorated because there is no consideration for the audio signal.

The present invention focuses on these points.
In a video tape recorder in which signals are recorded in the deep recording method and their reproduction is performed, without deteriorating the reproduction characteristics of the audio signal, it is necessary to properly perform the auto calibration of the recording level for the video signal. Aim.

[0006]

SUMMARY OF THE INVENTION The present invention provides a recording signal level auto-calibration apparatus for recording and reproducing a signal for auto calibration once on a magnetic tape and detecting an optimum recording signal level from the reproduction level. An audio signal recording means for recording an audio signal deeply on a magnetic tape at a constant recording level; and a video signal recording means for recording a video signal on a magnetic tape at a recording level of a number of steps superimposed on the audio signal. Signal reproducing means for reproducing the audio signal and the video signal recorded by these means, detecting the recording level of the video signal in which the reproduced level of the reproduced audio signal exceeds a predetermined reference value, and detecting the reproduced video signal. Detects the recording level of the video signal that maximizes the signal playback level , Characterized in that an arithmetic means for obtaining the recording level of the best video signal from the values of these records levels.

According to a main aspect of the present invention, the apparatus includes control signal recording means for performing recording by setting a duty ratio of a control signal at a recording start position of a video signal by the video signal recording means to a value different from that before and after the control signal recording means. It is characterized by having.

According to another main aspect, the video signal recording means of the apparatus has a function of performing signal processing indicating a change in a recording level step between video signals of each step of a recording level on a magnetic tape. It is characterized by having.

[0009]

According to the present invention, a video signal is superimposed and recorded at a recording level that changes stepwise on an audio signal of a constant level. Then, not only the video signal but also the audio signal is reproduced. The audio reproduction signal is compared with a predetermined reference value, and a recording level of the video signal whose reproduction level exceeds the reference value is detected.
As for the video signal, a recording level at which the reproduction level is maximum is detected. Then, using these detected recording levels, the optimum recording level of the video signal is set in consideration of the reference value of the audio signal.

According to the main mode, since the duty ratio of the control signal at the recording start position of the video signal is different from that before and after, the cueing at the time of reproduction is favorably performed. Also, between the video signals of each step of the recording level,
Since signal processing indicating a change in the recorded bell step, for example, forming a non-recorded portion of the video signal, is performed, the recording level step can be easily determined.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the recording signal level auto-calibration apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a main configuration of the present embodiment. As shown in the figure, in the present embodiment, a mechanism control CPU (hereinafter simply referred to as “CP”) for controlling the driving of the mechanism portion of the video tape recorder.
U ”) 10. This CPU
The recording / reproduction control unit 12 and the operation unit 14 are provided in the unit 10 in addition to a function part as a normal mechanism control.

The internal memory section 16 has an operation memory 18, a reference value storage section 20, a set level storage section 22, and a maximum recording level storage section for a video reproduction signal (hereinafter simply referred to as a "recording level storage section"). 24, a recording level storage unit having a reference value or more (hereinafter simply referred to as “recording level storage unit”) 26 is provided.

An automatic calibration switch 28, a signal recording / reproducing unit 30, and a nonvolatile memory unit 32 are connected to such a CPU 10. An auto calibration video recording level storage unit (hereinafter simply referred to as a “recording level storage unit”) is stored in the nonvolatile memory unit 32.
) And a factory-installed video recording level storage unit (hereinafter simply referred to as “recording level storage unit”) 36.

Next, the above components will be described in more detail. First, the recording / reproduction control unit 12 of the CPU 10 has a function of determining an operation mode by operating the auto calibration switch 28 and controlling signal recording and reproduction for the auto calibration. Arithmetic unit 14
Is for performing predetermined calculations, comparisons, and other processes using data such as a reproduction signal and reference values and recording levels stored in the memory unit 16.

Next, the operation memory 18 of the memory section 16
Is a memory area used for the processing of the arithmetic unit 14.
The reference value storage unit 20 stores a reference value of an audio signal described later. The set level storage unit 22 is for storing the optimum recording level of the video signal obtained by the auto calibration. The recording level storage unit 24 stores the recording level at which the video reproduction signal is maximized, and the recording level storage unit 26 stores the recording level at which the audio reproduction signal exceeds the reference value. belongs to.

Next, the auto-calibration switch 28 is for instructing the operation of the auto-calibration. The signal recording / reproducing unit 30 is for recording a signal for auto-calibration on a tape (not shown) based on an instruction from the CPU 10 or reproducing the signal, and has a configuration similar to that of a general video tape recorder. ing. The recording level storage units 34 and 36 of the non-volatile memory unit 32 include auto calibration,
This is for storing the recording level at the time of shipment from the factory.

Next, the signal recording / reproducing section 30 will be further described with reference to FIG. In FIG. 1, serial data of a recording level of a signal for a tape is input from a CPU 10 to an SP (serial-parallel) converter 50 together with a serial clock. The output side of the SP converter 50 is connected to a D / A converter 5
2, 54, and amplifiers 56, 58, respectively, are connected to the input side of the drum / head unit 60.

A video circuit 62 and an audio circuit 64 are connected to the drum / head unit 60, and video and audio signals to be recorded on a tape are supplied to the drum / head unit 60. ing. The CPU 10 controls flying drum erase, recording control of audio and video signals in the drum / head unit 60, and signal output control by the video and audio circuits 62 and 64. The audio circuit 6
4, the reference value of the reproduction level of the audio signal is output during the recording mode.

Next, the reproduction signal output side of the drum / head unit 60 is connected to an input switching unit 70 via amplifiers 66 and 68. The reference value output side of the audio circuit 64 is also connected to the input switching unit 70. The switching control of the input switching unit 70 is performed by a switching signal input from the CPU 10, and the output side of the input switching unit 70 is connected to the sample and hold circuit 72.

Further, a drum flip-flop (hereinafter simply referred to as "drum FF") signal of the drum / head unit 60,
That is, the output side of the pulse signal synchronized with the rotation of the head is connected to the servo control circuit 74. A control head section 76 is connected to the servo control circuit 74, and a drum FF output side is connected to a timing circuit 78.
Is connected to the sample-and-hold circuit 72.
The above-described serial clock, serial data for switching operation modes, and a duty recording / reproducing signal are input from the CPU 10 to the servo control circuit 74, and the drum FF signal is also input to the CPU 10.

Of the above components, the drum / head unit 60
Has two sets of heads, channels (ch) 1 and 2, so that an audio signal and a video signal are superimposed on the same track and recorded in a deep layer. The video circuit 62 is a circuit for recording and reproducing video signals, and outputs a non-modulated carrier when a signal indicating that auto-calibration is being performed is input from the CPU 10. Further, the audio circuit 64
A circuit for recording and reproducing audio signals.
Similarly, during auto calibration, a non-modulated carrier is output. Also, a reference value indicating the minimum necessary level of the audio reproduction signal is output.

Next, the input switching section 70 switches the input of video or audio based on the switching signal from the CPU 10. Sample hold circuit 7
Reference numeral 2 is for sampling and holding the input signal at the timing of the drum FF signal output from the timing circuit 78.

The servo control circuit 74 is for controlling and detecting the recording and reproduction of the control signal.
The duty ratio at this time is controlled as described later. As described above, the signal recording / reproducing unit 30
The configuration mainly uses an auto tracking circuit.

Next, the operation of the present embodiment configured as described above will be described. FIG. 3 shows a flowchart of the entire operation. This operation is executed in a series of operations in the video tape recorder.

<Recording of Video and Audio Signals for Auto Calibration> First, the operation of signal recording will be described. As shown in FIG. 3, when the auto-calibration switch 28 is operated (Step S1), this is detected by the recording / reproduction control unit 12 of the CPU 10, and the mode shifts to the auto-calibration mode (Step S1 in FIG. 3).
2). Then, the signal recording / reproducing unit 30 operates based on an operation instruction from the recording / reproducing control unit 12, and signal recording for auto-calibration on the tape is started (step S3 in FIG. 3).

At this time, a reference value is output from the audio circuit 64, and this reference value is captured by switching the input switching unit 70 to the audio side. The reference value is taken into the A / D conversion input side of the CPU 10 via the sample hold circuit 72 and the amplifier 80, and stored in the reference value storage unit 20 of the memory unit 16 (Step S4 in FIG. 3).

At the same time, a signal is recorded on the tape by changing the recording level in steps from the maximum to the minimum (step S5 in FIG. 3). Although the operation in step S5 is expressed in FIG. 3 as being performed subsequent to step S4, the operations in both steps are actually performed simultaneously. Hereinafter, the signal recording operation will be described in detail. FIG. 4 shows a time chart at the time of signal recording. FIG. 5 shows a detailed flowchart at the start of recording.

First, based on an operation instruction from the recording / reproduction control unit 12 of the CPU 10, after an appropriate timing delay,
The flying erase of the drum / head unit 60 is turned on (FIG. 4A, steps SA and SB in FIG. 5). As a result, signals already recorded on the tape are erased in track units. Thereafter, after an appropriate timing delay, recording of the audio signal for auto calibration is started (FIG. 4B, steps SC and S in FIG. 5).
D). That is, a constant level audio signal output from the audio circuit 64 is input to the drum / head unit 60 and recorded on the tape.

Next, in the case of auto-calibration, the servo control circuit 74 records the duty ratio of the control signal, for example, from 60% to 27.5% based on an instruction from the CPU 10 (FIG. 4).
(D), FIG. 5 steps SE, SF). Servo control circuit 7
Reference numeral 4 indicates a recording mode based on the serial data output from the CPU 10. And duty recording /
When the reproduced signal changes from "H" to "L" of the logical value, the duty ratio of the control signal is changed from 60% to 27.5%, and this is output to the control head unit 76 and recorded on the tape for, for example, 10 frames. (Step SG in FIG. 5).

Thereafter, the duty recording / reproducing signal becomes "H" of the logical value, and the duty ratio of the control signal is returned to 60% (step SH in FIG. 5). Subsequently, after a predetermined timing delay, recording of the video signal is started (FIG. 4 (E), steps SI, SJ in FIG. 5). That is, a video signal for auto calibration is supplied from the video circuit 62 to the drum / head unit 60 based on an operation instruction of the recording / reproduction control unit 12 of the CPU 10.

On the other hand, from the recording / reproducing control unit 12 of the CPU 10, serial data indicating the recording level is output together with the serial clock to the SP conversion unit 50, where it is converted into parallel data. Are supplied to a drum / head unit 60 after being processed by D / A converters 52 and 54 and amplifiers 56 and 58. drum/
In the head unit 60, a video signal is recorded on the audio signal at the input recording level (recording current level).

FIG. 4C shows how the recording level changes. As described above, the recording level changes in many steps (for example, 64 steps) from the maximum to the minimum. Here, as shown in FIG. 10E, for one recording level, video signals for eight frames are recorded.
An interval is provided between the video signals of each of the eight frames so that the video signal for one frame is not recorded. FIG. 6 (A) shows an enlarged view of FIG. 5 (E), and FIG. 6 (B) shows how video signals are recorded on a tape. Note that 8 frames correspond to 16 fields.

The recording operation of such a video signal will be further described with reference to the flowchart of FIG. When the edge of the drum FF signal is reached, recording of the video signal is started after an appropriate timing delay (FIG. 7).
Steps SK to SN). When the video signal is recorded for eight frames (steps SK, SL, SO in FIG. 7), the recording is terminated after an appropriate timing delay, and the next step of the recording level is set (steps SP to SR in FIG. 7). .

Then, before the end of all the steps, the recording of the video signal is started again after the timing delay (steps SK to SN in FIG. 7). The delay at this time forms a signal non-recording period for one frame. When the above operation is repeated and the recording of the video signal is completed for all steps of the recording level (step SS in FIG. 7),
Subsequently, the recording of the audio signal is also completed (step S in FIG. 7).
T), tape rewind for next playback search (REW)
(Step S in FIG. 7)
U). As described above, recording of the video and audio signals for the auto calibration is performed.

<Reproduction of Recorded Auto-Calibration Video and Audio Signals> Next, the operation of reproducing the signals recorded on the tape as described above will be described. First, the signal recording / reproducing unit 30 rewinds the tape based on an instruction from the recording / reproducing control unit 12 of the CPU 10, and returns the tape to the start point of signal recording (FIG. 3).
Step S6). Then, the video and audio recording signals are reproduced (step S7 in FIG. 3).

More specifically, in the CPU 10, following the end of signal recording, the servo control circuit 74 is controlled by serial data.
Is a playback mode. The servo control circuit 74 detects a change in the duty ratio, that is, a change from 60% to 27.5% shown in FIGS. 4D and 5 from the control signal reproduced by the control head unit 76. Then, a signal to that effect is output from the servo control circuit 74 to the recording / reproduction control unit 12 of the CPU 10. As a result, the head position of the signal recording is easily determined, and the recording start point is managed with high accuracy.

Next, in the drum / head unit 60, a normal signal reproducing operation is performed, and the reproduced video and audio signals are output. These signals are appropriately switched by the input switching unit 70 and the sample and hold circuit 72
Supplied to The selection of the switching input at this time is performed, for example, as shown in FIG. Figures (B) and (C)
As shown in FIG. 7, eight frames at a certain recording level, that is, 16 fields are numbered as "1, 2,..., 16".

Of these, for one channel of video, the video reproduction signals of the fifth and seventh fields are sampled and held, respectively, and taken into the CPU 10. For 2ch of video, the video reproduction signals of the fourth and sixth fields are sampled and held, respectively, and taken in. For one channel of audio, the audio reproduction signals of the eleventh and thirteenth fields are sampled and held, and are taken in. For audio 2ch, the audio reproduction signals of the tenth and twelfth fields are sampled and held, respectively, and taken in. These operations are sequentially performed for each recording level.

In a general auto-tracking circuit, signal sampling is performed in units of one frame. In this embodiment, sampling is performed in units of one field as described above.

<Detection of Optimal Recording Level> Next, the operation of detecting the optimum recording level of the video signal from the signal reproduced as described above will be described. The arithmetic unit 14 of the CPU 10 first calculates an average of these reproduced signals. That is, for one channel of video, the average of the video reproduction signals of the fifth and seventh fields is obtained, and this is treated as the video reproduction signal at the recording level. Others are the same.

Next, the arithmetic unit 14 sequentially compares the video reproduction signals obtained in this way, detects the recording level at which the video reproduction signal becomes the maximum, and stores it in the recording level storage unit 24 of the memory unit 16. . For example, assume that the reproduction level of a video signal recorded on a tape at the recording level shown in FIG. 8A is as shown in FIG. FIG. 3B shows the recording level of the audio signal.

As shown in this example, the recording level and the reproduction level of the video signal are not proportional, and even if the recording level is increased, the reproduction level does not increase beyond a certain level. In this example,
The reproduction level is maximum at the recording level WA indicated by the arrow FA. As described above, the recording level at which the reproduction level of the video signal is maximum is detected by the arithmetic unit 14 and stored in the memory unit 16 (Step S8 in FIG. 3). In particular,
The recording level at which the reproduction level of the video signal decreases from the maximum (the recording level before and after the recording level at which the reproduction level is the maximum) is obtained, and the average recording level of these recording levels is set as the maximum recording level. By performing such arithmetic processing, even when the reproduction level is flat as shown in FIG. 8C, the maximum recording level can be satisfactorily obtained with a small variation. These maximum recording levels are obtained for each channel of the head.

Next, the arithmetic section 14 detects a recording level at which the reproduced signal of the audio signal exceeds the reference value stored in the reference value storage section 20, and stores the detected recording level in the recording level storage section 26 of the memory section 16. (Step S9 in FIG. 3). The audio reproduction signal in the deep recording method changes linearly and inversely proportional to the recording level of the video signal, and becomes as shown in FIG. Here, assuming that the reference value is RV, the video recording level exceeding this (hereinafter simply referred to as “reference recording level”) becomes WB as indicated by arrow FB. This is required for each head channel.

When the reproduction of the recording signal is completed and the above-mentioned data is obtained, the operation section 14 performs an operation for obtaining an optimum recording level (step S10 in FIG. 3). Specifically, the optimum recording level is obtained as follows. (1) When the maximum recording level ≦ the reference recording level, the audio signal is reproduced larger than the reference value at the maximum recording level. Therefore, the maximum recording level is set as the optimum recording level. In the example shown in FIGS. 8A to 8D, the maximum recording level WA <the reference recording level WB
Therefore, the optimum recording level is WA.

(2) Conversely, when the maximum recording level> the reference recording level, the audio signal is reproduced at a lower level than the reference value at the maximum recording level.
The maximum recording level cannot be set as the optimum recording level. Therefore, if the reference recording level is within a predetermined range with respect to the maximum recording level, the reference recording level is set as the optimum recording level. If it is out of the range, the optimum recording level is set at a position closest to the reference recording level within a predetermined range with respect to the maximum recording level. Thus, the recording level of the video signal does not adversely affect its reproduction.

For example, if the video reproduction signal is as shown in FIG. 8 (E), the recording level at which the reproduction level becomes maximum becomes WC as shown by the arrow FC, which is higher than the reference recording level WB. However, if WB exists within a predetermined range of WC, reference recording level WB is set as the optimum recording level.

The optimum recording level obtained for each channel of the head as described above is stored in the set level storage section 22 of the memory section 16 and the recording level storage section 34 of the nonvolatile memory section 32 (FIG. 3). Step S11). Then, the signal recording / reproducing section 30 is driven by the CPU 10, and the tape is rewound while erasing the video and audio signals recorded as described above (FIG. 3).
Step S12). Thereafter, the recording / reproduction control unit 12 of the CPU 10 releases the auto-calibration mode (step S13 in FIG. 3), and executes processing such as normal recording as desired.

The recording level storage section 36 of the non-volatile memory section 32 stores the optimum recording level of the video signal obtained by auto-calibration using a reference tape at the time of shipment from the factory. Therefore, the recording level is used until the user performs the auto calibration after shipment from the factory. After the auto-calibration by the user, the optimum recording level detected thereby is used. However, when the value is significantly different from the value at the time of factory shipment, the value at the time of factory shipment is used.

As described above, according to the present embodiment, the following effects can be obtained. (1) Since signal recording for eight frames is performed for one recording level, signal reproduction can be performed satisfactorily without being affected by head contact, and the tape is less susceptible to dropout. . (2) Since the optimum recording level of the video signal is set in consideration of the reference value of the audio signal,
Deterioration of the reproduction characteristics of the audio signal is favorably prevented.

(3) Since the duty ratio of the control signal is changed at the start point of signal recording in the auto calibration, the head position of signal reproduction can be easily and accurately detected. (4) Since a signal non-recording portion is provided between video signals of each recording level, the recording level can be easily managed between steps.

<Other Embodiments> The present invention is not limited to the above-described embodiments. For example, various design changes can be made so that the circuit configuration shown in the above-described embodiments has the same operation. Yes, these are also included in the present invention.
Further, the specific numerical values shown in the above embodiments, for example, the number of frames of the video signal to be recorded per recording level, the number of steps of the recording level, and the like may be appropriately increased or decreased as necessary. In the above embodiment, the non-recording period is provided between the video signals of each step of the recording level, but other signal processing is performed such as positively inserting a signal indicating a step change. Already good.

[0052]

As described above, according to the recording signal level auto-calibration apparatus according to the present invention,
The following effects are obtained. (1) Since the optimum recording level of the video signal is set in consideration of the reference value of the audio reproduction signal, even in the case of the deep recording method, the video signal can be satisfactorily reproduced without deteriorating the reproduction characteristics of the audio signal. There is an effect that the recording level can be automatically calibrated with respect to.

(2) Since the duty ratio of the control signal at the start position of the signal recording for the auto calibration is changed, the reproducing operation can be performed satisfactorily. (3) Further, since signal processing indicating a level change between video signals of each recording level is performed, management between steps of each recording level can be easily performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a recording signal level auto-calibration apparatus according to the present invention.

FIG. 2 is a configuration diagram showing a part of the embodiment in detail.

FIG. 3 is a flowchart showing the entire operation of the embodiment.

FIG. 4 is a time chart showing an operation at the time of signal recording of the embodiment.

FIG. 5 is a flowchart showing a control signal recording operation at the time of signal recording in the embodiment.

FIG. 6 is a time chart showing a state of a recording signal on a tape and a reproducing operation thereof in the embodiment.

FIG. 7 is a flowchart showing a video signal recording operation in the embodiment.

FIG. 8 is a time chart showing an operation of detecting an optimum recording level in the embodiment.

[Explanation of symbols]

10: Mechanism control CPU, 12: Recording / reproduction control unit (audio signal recording means, video signal recording means, signal reproduction means), 14: Operation unit (calculation means), 16
... Memory part, 18 arithmetic operation memory, 20 reference value storage part, 22 setting level storage part, 24 maximum recording level storage part for video reproduction signal, 26 recording level storage part with reference value or more, 28 auto Calibration switch, 30... Signal recording / reproducing unit (audio signal recording means, video signal recording means, signal reproducing means), 32
... Non-volatile memory unit, 34 ... Auto calibration video recording level storage unit, 36 ... Factory shipping video recording level storage unit, 50 ... SP conversion unit, 52, 54 ... D /
A converter, 56, 58, 66, 68, 80 ... amplifier, 6
0: drum / head unit, 62: video circuit, 64: audio circuit, 70: input switching unit, 72: sample and hold circuit, 74: servo control circuit (control signal recording means), 76: control head unit (control signal recording) Means), 78: timing circuit, FA to FC: arrow, RV: reference value, WA, WC: maximum recording level, WB: reference recording level.

Claims (3)

(57) [Claims] An auto-calibration apparatus for recording a signal for auto-calibration once on a magnetic tape and reproducing the same, and detecting an optimum recording signal level from the reproduction level. Audio signal recording means for recording a signal in a deep layer on a magnetic tape, video signal recording means for superimposing the audio signal on the magnetic signal and recording a video signal on the magnetic tape at a recording level of a number of steps, and recorded by these means Signal reproducing means for reproducing an audio signal and a video signal; detecting a recording level of a video signal in which a reproduced level of the reproduced audio signal exceeds a predetermined reference value; and maximizing a reproduced level of the reproduced video signal. Detects the recording level of the video signal and calculates the value of these recording levels. Calculating means for calculating an optimum recording level of a video signal from the apparatus. 2. The control signal according to claim 1, wherein the duty ratio of the control signal of the recording start position of the video signal by the video signal recording means is set to a value different from that before and after the video signal recording means. An auto-calibration device for a recording signal level, comprising recording means. 3. The recording signal level auto-calibration apparatus according to claim 1, wherein said video signal recording means changes a recording level step between video signals of each step of a recording level on a magnetic tape. A recording signal level auto-calibration apparatus having a function of performing signal processing indicating the following.