KR890005007B1 - Magnetic recording-displaying device - Google Patents

Abstract

The circuit automatically self controls the head resonance frequency, the output level of the reproducing circuit, and the optimized recording signal level according to the magnetic media. The circuit comparises the record part recording the stair case signals on the magnetic media to find the appropriate signal level, the high signal level detector finding the highest voltage signal of the output level controller which continuously varies the signals for the head resonance frequency controller, and the memory circuit memorizing the acquired data.

Description

Magnetic recording and playback device

1A and 1B are block schematic diagrams of a general magnetic recording / reproducing apparatus capable of processing digital signals, respectively.

2A and 2B are block schematic diagrams of a recording system and a reproduction system of one embodiment of the present invention, respectively.

3 is a flowchart for explaining the operation of the apparatus of the present invention.

4A to 4C are timing charts for explaining the operation of the apparatus of the present invention.

5A and 5B are some block schematic diagrams of another embodiment of the apparatus of the present invention.

6 is a swept signal reproduction waveform diagram.

7 is a circuit diagram of an essential part of a conventional apparatus.

8 is a schematic block diagram of an example of a magnetic reproducing apparatus for performing digital signal processing, which is the same as that of FIG. 1B.

9 is a block schematic diagram of an essential part of an embodiment of the apparatus of the present invention.

10A and 10B are flowcharts for explaining the operation of the apparatus of the present invention.

* Explanation of symbols for main parts of the drawings

1: Input terminal 3, 10: AD converter

5, 12, 21, 24, 26: DA converter 7: Magnetic head

8 magnetic tape 14 control circuit

14 ₁ : gain variable part 14 ₂ : operation time control part

17: voltage control amplifier 18, 19, 20, 28: interface

22: memory 23, 25: amplifier

27: sampling level detector 101: magnetic head

103: magnetic tape 104: AD converter

108, 110: DA converter 109: variable capacitance diode

112: automatic adjustment circuit 113: control circuit

113 ₁ : control signal output unit 113 ₂ : comparison unit

114: sampling level detector 114 ₁ : maximum value detection circuit

114 ₂ : operation timing control circuit 114 ₃ , 115, 118: register

114 ₄ , 117: interface 116: memory

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus, and in particular, an optimum recording level can be automatically adjusted, a head resonant frequency and Q can be automatically adjusted respectively, and predetermined sampling is performed at a level detector of a level of a reproduction signal converted into a digital signal. The present invention relates to a magnetic reproducing apparatus which is configured to detect by timing.

In the conventional magnetic recording and reproducing apparatus, when trying to obtain the optimum recording level on a signal magnetic tape, conventionally, the characteristics of the standard magnetic tape are measured to obtain a setting value of the recording level, and then the standard signal is input. The semi-fixed resistor for input adjustment of the recording amplifier was adjusted so that the recording current of the magnetic head was at the set value.

However, the conventional method requires a lot of work and time, and accordingly, there is a problem in that the manufacturing cost is high. In addition, since this is a mechanical adjustment, there is a problem that it is easy to cause a change over time. Moreover, there was a problem that the performance of magnetic tapes with different characteristics could not be sufficiently drawn.

The present invention provides recording means for sequentially changing the level of an input signal on a magnetic tape in a stepwise manner at a predetermined timing, recording means for reproducing a signal from the magnetic tape, detecting the level at a predetermined timing, and detecting a maximum reproduction level; The above problem is solved by a configuration comprising means for storing the recording level of the recording means at the timing of obtaining the maximum reproduction level.

In the related art, a resonant circuit is generally formed on the magnetic head output side of a video signal self-reproducing apparatus by the inductance of the magnetic head itself and the capacitance generated between the magnetic head and the ground. Head resonance frequency) and a predetermined value determined in advance by design.

For example, a magnetic tape on which test signals such as a sweep signal (a signal whose level is constant and the frequency changes continuously) is recorded, is reproduced, and a reproduction waveform shown in FIG. 6 is obtained with an oscilloscope. P ₁ , P ₂ ,... Is a pulse waveform section showing the division of each frequency, and f is the head resonance frequency of this magnetic head.

Thereby, in the related art, the adjuster observes the reproduction waveform shown in FIG. 6 and between the first channel magnetic head 101 ₁ and the preamplifier 102 ₁ shown in FIG. 7 and the second channel magnetic head 101. ₂ ) and trimmer capacitors C ₁ and C ₂ respectively provided between the preamplifier 102 and the preamplifier 102 ₂ were adjusted so that the frequency (resonant frequency) indicating the maximum amplitude of the reproduction waveform was adjusted to the predetermined value. On the other hand, while observing the reproduction waveform shown in FIG. 6, the variable resistors VR ₁ and VR ₂ were varied so that Q was at the predetermined value (actually, the ratio of level a and level b was settled).

In the conventional method described above, trimmer capacitors C ₁ and C ₂ and variable resistors VR ₁ and VR ₂ need to be adjusted, which requires a lot of work or time, and requires an oscilloscope, thereby increasing the manufacturing cost. there was. Moreover, since the conventional apparatus adjusts mechanically, it is easy to produce secular variation, and there exist some problems, such as the disparity immediately after adjustment and the time of shipment.

The present invention provides means for converting a signal reproduced from a prerecorded magnetic tape to a digital signal, a head resonant frequency adjusting means for varying a head resonant frequency by varying an output control voltage, and a variable for changing a resistance value. Q control means for varying?, Control signal output means for outputting control signals for continuously varying the output control voltage of the head resonant frequency adjusting means and the resistance value of the Q adjusting means, respectively; Maximum value detection means for detecting the maximum output of the conversion means, comparison means for detecting that the output ratio of the conversion means at the time of two preset samplings becomes a preset value, and at the maximum value detection by the maximum value detection means. A control signal according to the output control voltage of the head resonant frequency adjusting means; This problem is solved by providing a storage means for storing control signals corresponding to the resistance values of the Q adjusting means at the time of detection by the comparison means.

In addition, conventionally, the level detector used in the FMAGC circuit cannot extract the detection output only at any timing because its output is a signal that is normally continuous.

For example, in the magnetic recording and reproducing apparatus, when detecting the reproduction signal level from the magnetic tape and adjusting the head resonant frequency Q, the recording level, and the like based on this level detection signal, the conventional level detector uses only a specified timing. There was a problem that it was difficult to construct a circuit so that the detection output in the system could not be taken out, the output could be directly supplied to the CPU for digital processing, and the above adjustments could be automated. In addition, in the case of using the conventional level detector, there is a problem in that the minimum one field period must be the same frequency for the CPU to detect the head resonance frequency, and thus a long time is required to provide information in a wide frequency range.

The present invention provides an AD converter circuit for converting a signal reproduced from a prerecorded magnetic tape to a digital signal, a level detector for detecting the output level of the AD converter circuit according to a designated sampling timing, and a control circuit for designating a sampling timing. The above problem is solved as a configuration in which the configuration is provided, and the embodiment will be described below together with the drawings.

In recent years, television receivers for digitally processing television signals and imaging them have been developed (for example, "Nikkei Electronics" November 23, 1981, p. 233 to 247). However, the present invention also uses magnetic recording to perform digital signal processing. Applied to the playback device. At the time of writing, as shown in FIG. 1A, the signal entering the terminal 1 is amplified by the amplifier 2 and then converted into a digital signal by the AD converter 3, and supplied to the signal processing circuit 4 for excitation. Each operation of luminance signal and carrier color signal separation, FM modulation, carrier color signal frequency conversion, APC, ACC, pre-emphasis, etc., as known in the above, is processed as a digital signal, and then converted into an analog signal in the DA converter 5. It is converted, and amplified by the amplifier 6 and then recorded on the magnetic tape 8 in the magnetic head 7.

On the other hand, during reproduction, as shown in FIG. 1B, the video signal reproduced from the magnetic tape 8 from the magnetic head 7 is amplified by the preamplifier 9 and then converted into a digital signal by the AD converter 10. FIG. To the signal processing circuit 11 to perform respective operations such as luminance FM signal and carrier color signal separation, FM demodulation, carrier color signal frequency conversion, APC, ACC, de-emphasis, noise limiting It is processed as a digital signal, and then converted into an analog signal by the DA converter 12 and taken out from the terminal 13.

2A and 2B respectively show block schematic diagrams of the recording system and the reproduction system of the magnetic recording and reproducing apparatus according to the present invention. 14 is a control circuit composed of, for example, a CPU and the like, and is shown in FIG. The operation according to the flowchart is performed.

At the time of writing, in FIG. 2A, the switching signal a shown in FIG. 4A is taken out from the control circuit 14 via the interface 18, and the switch circuit 15 is turned off (third intermediate step). (50) The signal from the AD converter 3 is cut off, and a 5 MHz carrier frequency signal (test signal) is taken out via the interface 19 (step 51). 16 is supplied to the FM modulator 4a of the signal processing circuit 4, and then FM-modulated, converted into an analog signal by the DA converter 5, and supplied to the voltage control amplifier 17.

Here, the gain variable control signal according to the operation timing of the operation time control unit 14 ₂ is taken out from the gain variable unit 14 ₁ of the control circuit 14, and the analog signal is output from the DA converter 21 via the interface 20. Is converted to the voltage control amplifier 17 as a control voltage, and the gain of the voltage control amplifier 17 is changed stepwise (step 52). Accordingly, the test signal changes the recording level stepwise, and is recorded on the magnetic tape 8 as shown in FIG. 4B.

As a means for changing the recording level of the test signal in a stepped manner, there are circuits shown in FIGS. The circuit shown in FIG. 5A changes the resistance value of the DA converter 24 (substantially negative feedback resistor) provided between the input and output terminals of the amplifier 23 as the gain variable control signal from the memory 22, and thereby the amplifier 23 The gain of the amplifier is changed, and the output of the amplifier 23 is taken out through the recording amplifier 25. The circuit shown in FIG. 5B varies the resistance value of the DA converter 26 as a gain variable control signal from the memory 22 to change the level of the input signal, and records the output of the DA converter (variable resistor) 26. Take out via the amplifier 25.

At the time of reproduction, in FIG. 2B, the magnetic tape 8 in which the test signal is recorded is rewound and reproduced by the tape rewind control circuit from the control circuit 14 (step 53), and the reproduction output level Is a waveform shown in FIG. 4C, for example.

The operation timing control signal from the operation time control unit 14 ₂ of the control circuit 14 is supplied to the sampling level detector 27 via the interface 28, and the operation timing of the sampling level detector 27 is sequentially changed. (Step 54). The reproduction output level at each operation time is always monitored, and if the maximum value of the reproduction output is detected at time t (step 55), the value of the register of the DA converter 21 at the time t that recorded this signal at the time of recording was recorded. This memory 22 is stored (step 56). This value is a value which can obtain the gain of the amplifier 17 which can be optimally recorded.

The adjustment is made for the right channel and the left channel of the magnetic head, respectively. Alternatively, the recording level in one field period may be changed and recorded by using the signal a shown in FIG. 4A as a rectangular pulse, and the recording level may be recorded by converting the recording level in units of one.

As shown in FIG. 8, the video signal reproduced by the magnetic head 101 from the magnetic tape 103 is amplified by the preamplifier 102 and then converted into a digital signal by the AD converter 104, and signal processing. Each operation such as luminance FM signal and carrier color signal separation, FM demodulation, carrier color signal frequency conversion, APC, ACC, de-emphasis, noise limiting, etc., supplied to the circuit 105 and processed herein, is processed as a digital signal. Then, it is converted to an analog signal in the DA converter 106 and taken out from the terminal 107 as shown in FIG. 1B.

9 is a block diagram showing the main parts of an embodiment of the magnetic regeneration device of the present invention. The part enclosed by the broken line in the figure is the automatic adjustment circuit 112. The capacitance of the variable capacitor diode 109 is varied in the output control voltage of the DA converter 108, so that the resonance frequency is adjusted and the resistance value of the DA converter 110 is performed. Q adjustment is performed by the variable, respectively. 113 is a control circuit comprised of a CPU etc., for example, and the operation | movement according to the flowchart shown to FIG. 10A (resonance frequency adjustment) and 10B (Q adjustment) is performed. C ₃ and C ₄ are DC blocking capacitors.

Here, the magnetic tape 103 on which a test signal such as a sweep signal (a signal whose level is constant and whose frequency is continuously changed) is recorded. If the reproduced signal is temporarily observed with an oscilloscope, the reproduced waveform shown in FIG. 6 can be obtained. P ₁ .P ₂ ,. Denotes a pulse waveform portion that indicates a division of each frequency, and f denotes a head resonance frequency of the magnetic head.

First, resonant frequency adjustment is described. For example, the coordinator sets the head resonant frequency (e.g., 5 MHz) designed by Denki et al.

As a result, the control signal from the control circuit 113 is supplied to the operation timing control circuit 114 via the bus, the interface 114 of the sampling level register 114, and the register 114 ₃ to operate back and forth around the 5 MHz. Start start and end time of operation (i.e., sampling range) are set (step 130 during step 10a).

Subsequently, the value of the register 115 of the DA converter 108 is converted by the control signal from the control signal output unit 113 of the control circuit 113 (step 131) to output the control voltage of the DA converter 108. Is variable, thereby varying the capacitance of the variable capacitor diode 109 and thus the resonant frequency. At this time, the maximum detection circuit 114 ₁ of the sampling level register 114 monitors the reproduction level in the frequency range (sampling range) corresponding to the operation start time and the operation end time, and detects the maximum value in the sampling range. (Step 132). When the maximum value is detected, the output data of the register 115 at this time is stored in a memory (e.g., an EEPROM (electrically erasable program type (ROM) 116) which does not lose information contents even when the power supply is cut off (step 133)). The output data of the register 115 at this time is a value for obtaining the head resonance frequency 5 MHz which is designed.

On the other hand, the interface 117 records data sent from the control circuit 113 via the bus and stores the data in the register 115 and the register 118 described later. Once data is stored in the registers 115 and 118, it is not always necessary to send data from the control circuit 113.

Next, Q adjustment will be described. The output data of the register 115 is set to a value that obtains the head resonance frequency 5 MHz, and for example, the adjuster sets the designed Q (probably the ratio x between levels a and b during the sixth time) by the tenkey shift.

By the control signal from the control circuit 113, the operation start start and operation end time (sampling range) of the sampling level register 114 are set to correspond to the frequency before and after the sixth intermediate level a (step 10b). 134).

Subsequently, the value of the register 118 of the DA converter 110 is varied by the control signal from the control signal output unit 113 ₄ of the control circuit 113 (step 135), whereby the DA converter 110 The resistance value is varied, thereby changing the reproduction output level. The maximum value of the reproduction output level in the sampling range is detected by the maximum value detection circuit 114 ₁ and stored in the memory 116 as A (step 136).

On the other hand, by the control signal from the control circuit 113, the operation start time and operation end time (sampling range) of the sampling level detector 114 are set to correspond to the front and rear of the frequency corresponding to the level b during the sixth step (step 137). Subsequently, the maximum value of the reproduction output level within the sampling range is detected by the maximum value detection circuit 114 ₁ , and this maximum value is stored in the memory 116 as B (step 138). Subsequently, B / A = X is determined by the comparing unit 113 ₂ of the control circuit 113 (step 139). The output data of the register 118 of the DA converter 110 at this time is a value for obtaining the Q whose output data of the memory 116 is predetermined by design.

Such low dynamics adjustment is performed for the first channel and the second channel, respectively.

On the other hand, in the four-head type magnetic reproducing apparatus each having a dedicated magnetic head in the standard mode and the long time mode, the magnetic tape corresponding to the mode is reproduced, the same automatic adjustment is performed, and the data for each magnetic head is stored in the memory 116. To be stored.

In addition, although the sampling level detector in this embodiment is used for detecting the reproduction signal level when adjusting the head resonance frequency and Q, respectively, the present invention is not limited thereto, and the detection signal level detection when adjusting the recording level is similarly performed. Applicable

As described above, the magnetic recording and reproducing apparatus according to the present invention includes recording means for sequentially varying and recording a level of an input signal on a magnetic tape stepwise at a predetermined timing, and reproducing the signal from the magnetic tape to set the level at a predetermined timing. Means for detecting and detecting the maximum reproduction level, and means for storing the recording level of the recording means at the timing at which the maximum reproduction level is obtained, so that the optimum recording level can be automatically set and the input of the amplifier can be adjusted. Compared to the conventional one, which has adjusted the semi-fixed resistance, it takes less work or time, and because the manufacturing cost is low and the electronic adjustment is performed, no change occurs over time. Furthermore, the optimal recording level for the characteristics of the magnetic tape is achieved. It can be set such as.

In addition, the magnetic reproducing apparatus of the present invention is provided between a converting means for converting a signal reproduced from a prerecorded magnetic tape to a digital signal, and a magnetic head for reproducing a signal from the magnetic tape and the converting means, thereby providing an output control voltage. A head resonant frequency adjusting means for varying the head resonant frequency by varying the?, Q adjusting means provided between the magnetic head and the converting means and varying Q by varying the resistance value, and output control of the head resonant frequency adjusting means. Control signal output means for respectively outputting a control signal for continuously varying the voltage and the resistance value of the Q adjusting means, a maximum value detecting means for detecting the maximum output of the exchange means at the time of preset sampling, and a preset value The output ratio of the conversion means at the time of two sampling is preset A comparison means for detecting the value, a control signal according to the output control voltage of the head resonance frequency adjusting means at the time of detecting the maximum value by the maximum value detecting means, and a resistance value of the Q adjusting means at the time of detection by the comparing means. Since the memory means for storing the control signals are provided separately, the head resonant frequency and Q can be adjusted automatically, and there is no need to adjust the trimmer capacitor or the variable resistor as in the conventional device, and the hand and time can be greatly reduced, and the oscilloscope No need for a waveform observing device, etc., thereby lowering the manufacturing cost compared to the conventional device. Moreover, since it is an electronic adjustment as opposed to the mechanical adjustment of the conventional device, there is no secular variation, and a magnetic tape in which a test signal such as a sweep signal is recorded. Can be adjusted automatically by just playing Or seoeobiseu top also can be easily handled by the standard addition adjustment head and a long period of time the head has the advantages of being easily fixed by just putting the grind adjustment data.

In addition, the magnetic reproducing apparatus of the present invention includes an AD conversion circuit for converting a signal reproduced from a prerecorded magnetic tape to a digital signal, a level detector for detecting the output level of the AD conversion circuit according to a specified pleating timing, and sampling timing. By designing a control circuit to designate, it is possible to take out a detection output only at a specified timing, and to process the reproduced signal digitally using a CPU or the like, for example, a resonance frequency Q, a recording level, or the like. Each adjustment can be automated and the adjustment can be performed in a short time.

Claims (6)

A first AD converter 3 for converting an input signal into a digital signal, a signal processing circuit 4 for signal processing the output signal of the first AD converter 3, and a digital output from the signal processing circuit 4; The first DA converter 5, which converts the signal into an analog signal, the first DA converter 5, and the level of the output signal of the first DA converter 5 are sequentially changed in a stepped shape at a predetermined timing so that the recording head ( 7) a recording circuit for recording on the magnetic tape 8, a second AD converter 10 for converting a signal reproduced from the recorded magnetic tape 8 into a digital signal, and from the second AD converter 10; A level detector 27 for detecting the maximum reproduction level of the output signal, an operation time control unit 14 _{2 for} controlling the operation timing of the level detector 27 via the first interface 28, and the level detector ( The maximum reproduction level detected by The magnetic recording and reproducing apparatus comprising: a memory (22) for. 2. The recording circuit according to claim 1, wherein the write circuit gains by a voltage control amplifier (17) varying the level of the output signal of the first DA converter (5) and an operation timing output from the operation time control unit (14 ₂ ). variable gain section (14 ₁₎ which outputs a variable control signal, the gain is variable gain control signal outputted from the variable portion (14 ₁₎ is supplied via the second interface 20, steps the voltage amplifier 17 And a second DA converter (21) for controlling in shape. 2. The memory according to claim 1, wherein the writing circuit is connected to a first amplifier (23) for amplifying the level of the output signal of the first DA converter (5) and the first amplifier (23). And a negative feedback resistor (24) whose resistance varies with the output signal of the magnetic recording and reproducing apparatus. The resistance of claim 1, wherein the write circuit has a resistance value varied by a second amplifier 25 that amplifies the level of the output signal of the first DA converter 5 and an output signal of the memory 22. And a variable resistor (26) for varying the input signal level of the second amplifier (25). An AD converter 104 for converting an analog signal reproduced from a recording signal magnetic tape 103 into a digital signal, a magnetic head 101 for reproducing an analog signal from the magnetic tape 103, and the AD converter 104; Interposed therebetween, the output control voltage of the first DA converter 108 is varied according to the value of the first resistor 115 so as to vary the head resonant frequency while changing the capacitance of the capacitor 109 and at the same time the second resistor. An automatic adjustment circuit 112 for varying the Q by varying the resistance of the second DA converter 110 by a value of 118, and outputting a control signal to the automatic adjustment circuit 112 via the interface 117; At the same time, the control signal output unit 113 ₁ for setting the sampling time and the level detector 114 for detecting the maximum output of the AD converter 104 at the time of sampling preset by the control signal output unit 113 ₁ . And the control signal output unit. At the time of two sampling preset by 113 ₁ , a comparison circuit 113 _{2 for} detecting that the output ratio of the AD converter 104 has become a preset value, and at the time of detecting the maximum value of the level detector 114. the control signal output unit (113 _1), the magnetic reproducing apparatus characterized in that comprises a memory 116 for storing a control signal for output to the automatic adjustment circuit 112. A magnetic head 101 for reproducing an analog signal from a recording signal magnetic tape 103, an amplifier 102 for amplifying a signal reproduced by the magnetic head 101, and an output signal of the amplifier 102. The AD converter 104 which converts into a digital signal, the signal processing circuit 105 which performs the signal processing of the digital signal output from the DA converter 104, and the signal output from the signal processing circuit 105 are analog signals. A magnetic reproducing apparatus having a DA converter 106 for converting to a WHEREIN, the control circuit 113 for designating the sampling timing of the output signal of the AD converter 104 and the sampling timing designated by the control circuit 113. And a level detector (114) for detecting the output level of the AD converter (104).

Images