JPS636922B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for signal transmission or signal storage on a magnetizable information carrier.

In another configuration, the invention is used for storing signals on a magnetizable information carrier, such as magnetic tape or cine film with a magnetic soundtrack, to which a recording head and an erasing head are associated. Preferably both heads can be supplied with a high-frequency signal for bias magnetization or for erasing already stored signals, the operation of the erasing head being able to be interrupted at a moment's notice and the memory being erased. The present invention relates to a device in which the level of an output signal is adjustable.

Small motion picture film or tape amateurs may make subsequent recordings to audio recordings already made on magnetic tracks of tape or cinefilm for the purpose of script composition, in which case the recordings that have already been made may be completely overwritten. is not deleted. In this way, a miniature motion picture film can, for example, already have music recorded in the first recording step and a verbal commentary recorded in the second step, the music recording being replaced by the second recording. It is attenuated and becomes so-called background music. For this reason, it has already been proposed to store music in a first recording process and to store explanations, noises, etc. superimposed on the already recorded music signal in a second recording process. However, during the second recording process, according to known proposals, the erasing head is switched off and the level of the signal to be recorded is adjusted depending on the script requirements. Since consideration is given to adjusting the level of the signal to be recorded and at the same time matching the amplitude of the high frequency bias magnetization signal, recording with less distortion is achieved.

According to this known proposal, in order to carry out this multiple recording, at least the expense of a switch for turning off the erasing head and a voltage divider for adjusting the degree of level control of overlapping recording is required on the device side. The object of the invention is to provide a signal storage device capable of carrying out multiplex recording as described above, in such a way that component costs on the device side are avoided or kept low.

According to the present invention, there is provided a recording level varying means for varying the level of a recording signal supplied to the recording head, and a level of an erasing bias current supplied to the erasing head in accordance with the operation of the recording level varying means. A device for transmitting a signal or storing a signal is constituted by the variable erasing level variable means.

According to the invention, therefore, the following is proposed in a device as described above. That is, an adjustable voltage divider is provided, the taps of which are connected to a common reference potential for the write magnetic head and the erase magnetic head, and the erase head is connected through one terminal of the voltage divider. can be connected to a reference potential, and the other terminal is supplied with at least the signal to be memorized, so that depending on the selection or adjustment of the taps of the voltage divider, the already memorized signal can be erased or a selectable level The storage according to the information carrier can optionally be carried out superimposed on signals already stored on the information carrier. This special measure advantageously avoids a switch that shuts off the erase head. Depending on the adjustment of the voltage divider, the erasing head is disabled or the degree of level control of the superimposed recording is adjusted. The degree of attenuation of existing recordings also depends on the degree of this level control. For the device manufacturer, the measures according to the invention mean the saving of switches for disconnecting the erasing head, the elimination of connecting lines between the component board and the switches accessible to the user, and the simplification of the operating elements. This means that the device will be cheaper not only for the manufacturer but also for the consumer. As for the effect, at least the same result as a device with a switch can be obtained,
However, in the device according to the invention,
Compared to known proposals with switches, it is advantageous that a noiseless transition between erasing and already existing recording or only attenuating this recording takes place.

In another embodiment, the invention is used for a signal transmission device with automatic signal conditioning, in which the amplification of the conditioning stage is functionally related at least to the magnitude of the useful signal to be transmitted. The present invention relates to a device in which an adjustment signal is extracted from the useful signal and is supplied as a control signal to an actuator for adjusting the amplification degree or to a controllable attenuator or the like.

Amateur tapes, small motion picture film Amateur users must concentrate their attention on the operation and level control of the equipment used. Particularly if this requires additional visual tracking of events,
This is a big burden for amateurs,
For example, this is unavoidable when shooting small-sized movies. Automatic level control is advantageous for the recording device of such devices. The automatic level control allows recordings to be made of sufficient quality without the need to constantly monitor instruments or operate knobs (level control regulators).

However, on the other hand, a recording device that only performs recording using automatic level control is not always optimal. A predetermined dynamic compression is achieved by an automatic level control stage;
A certain averaging is then carried out in scenes with widely different sound levels, which results in a loss of reproduction fidelity in dramatic scenes or a deterioration of the sound pattern. For such recordings, it is advantageous to use a recording device that allows the user to manually control the audio level.

It has already been proposed to use automatic level control stages in audio recording devices in which the mode of operation "automatic level control" can be switched off and the recording level can be adjusted manually via a rotary knob or the like. In this case, the shaft of the setting adjuster is connected to a mechanical switch,
This switch engages or disengages the automatic level control in one final position. Such a switchable device offers the advantage to the user that the device can always be used optimally depending on the acoustic conditions. However, certain construction costs are required for the device manufacturer. This is because, in addition to the level regulator, a mechanical switch must be provided, which requires a certain amount of expense and also requires a certain amount of considerable space, which is especially important today when the equipment is compact. This is because it cannot be ignored when there is a tendency to

It is therefore an object of the invention to provide a device for a signal transmission device which allows automatic level control of the signal transmission device and manual level control by the user, while not only keeping component costs low. , so that the required space is gradually reduced. For consumer-friendly maintenance-free equipment, the setting of individual operating modes can also be done entirely electronically.

Therefore, according to the present invention, the following is proposed in the above-mentioned device. This means that an adjustable resistor is arranged preferably in parallel with the actuating element, and this resistor is a partial resistance of the voltage divider, via which the function of the actuating element is at least partially determined. The voltage divider is preferably a manually operable potentiometer.

According to the invention, the selection of the mode of signal transmission (automatic level control or manual level control) can be performed exclusively via electronic and non-consumable components. Since mechanical transfer switches with large space requirements are not used, desirable small configurations such as tape recorders, cine cameras, movie projectors, etc. are not impeded.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a magnetic tape is indicated at 1, which is passed at an erase head 3 and a record head 4 at a uniform speed in the direction of arrow 2 by a drive, not shown. do.
A signal to be recorded is supplied to the recording device via a terminal 5, and this signal is amplified in an amplifier 6. The amplifier 6 has an automatic gain control, not shown in detail, which derives a control signal from the magnitude of the output signal, which controls the amplification of the amplifier 6 depending on the magnitude of the input signal. Since the amplitude is increased more or less, a signal with an amplitude sufficient for recording on the magnetic tape 1 is almost always available at the input terminal of the amplifier 7. The recording amplifier 7 supplies a constant recording current to the recording magnetic head 4 through a (linearizing) resistor 8 regardless of the frequency. A high frequency generator is indicated by 9;
This high frequency generator is provided to control the erase head 3. In addition, a high-frequency signal is also supplied via a capacitor 10 to the recording magnetic head 4, which signal is used for bias magnetization.
As is known, this bias magnetization is necessary for low distortion and high quality recording of the useful signal.

If another recording is to be made superimposed on the recording already existing on the magnetic tape 1, this will apply to the second recording.
This can be done by the circuit device shown in the figure. According to FIG. 2, the recording amplifier 7 is supplied with the useful signal to be recorded via an input terminal 11 (not shown). The output signal of the recording amplifier 7 is connected to the resistor 12.
and is supplied to the recording head 4 via 13 series circuits. However, as shown in FIG.
A high frequency bias magnetization signal is also provided. FIG. 2 shows the oscillator oscillator circuit 14 of the high-frequency generator 9, and the output coupling winding 1 of this high-frequency generator.
5, a bias magnetization signal for the recording magnetic head 4 and an erase current for the erase head 3 are supplied.

Since small-format movie amateurs perform overdubbing or "trick recording," the erasing head 3 must not erase existing recordings during overlapping recording. The other terminal of the erasing head 3, which is connected via one terminal to the output coupling winding 15 of the high-frequency generator 9, is connected to the terminal 1 of the adjustable voltage divider 17.
6. The adjustable voltage divider 17 is configured as a voltage divider in which the slider 18 is connected to a reference potential (earth). Depending on the voltage division ratio or the setting of the slider, the erasing head 3 is connected to the reference potential via a more or less large resistor. When the slider 18 of the voltage divider 17 contacts the terminal 16, the erase head 3 is fully active. On the other hand, if the slider moves away from terminal 16 of the voltage divider, terminal 16
The resistance between the eraser and the slider 18 increases, which, depending on the setting of the slider, causes more or less attenuation of the high frequency signal amplitude in the erase head, or causes the erase head to become inoperable.

Tap 20 of a series circuit consisting of resistors 12 and 13
is connected to terminal 19 of voltage divider 17 according to FIG. As a result, when adjusting the slider 18 in the direction of the terminal 19, the useful signal supplied by the recording amplifier 7 is attenuated, and in addition corresponds to the resistance value set between the slider 18 and the terminal 19 of the voltage divider. It will be attenuated to a certain extent. The arrangement of the voltage divider 17 therefore provides a simple possibility of cutting off the erasing head and at the same time adjusting the level of further recordings recorded over the already existing recordings in a more or less continuous manner. It will be done. However, in addition, via the voltage divider 17, the amplitude of the high-frequency bias magnetization signal supplied to the recording head 4 via the capacitor 10 is also adjusted, so that when the effective signal amplitude decreases, the high-frequency signal amplitude also decreases. Therefore, recordings are always made with sufficient sound quality.

The voltage divider 17 can be configured as a potentiometer, the slider of which can be operated via an adjustment knob on the front panel of the device. But instead of a mechanical voltage divider, e.g. a photoresistor,
It is also conceivable to use voltage dividers formed from other components that can accomplish this by means of semiconductor sections. Non-mechanical control of such voltage dividers can be performed via DC control signals, optical signals, etc. The adjustable voltage divider is designed to have a positive logarithmic curve profile, in which case, according to FIG. Comes with. Thereby terminal 16 of voltage divider 17
If the slider is turned away from the eraser head 3, a large resistance is obtained already after a small adjustment stroke between the terminal 16 and the slider 18, so that the erase head 3
becomes invalid. If the user is to be informed of the activation or deactivation of the erase head 3, the terminal 16 connects an electronic switch stage, which is activated when the slider 18, ie the ground potential, is connected to the terminal 16 of the voltage divider 17. It is conceivable that a switch stage activates or deactivates the optical signal device. However, in this switch stage, the high-frequency signal at the erasing head 3 or the terminal 1 of the voltage divider 17 may be
Provision is made to ensure that low frequency signals supplied via 9 do not initiate the switching process.

In FIG. 3, a magnetic tape is indicated at 101, which is moved by a drive (not shown) at arrow 102 for recording acoustic signals.
erase head 10 of the recording device at a uniform speed in the direction of
3 and recording head 104.
A signal to be recorded is supplied to the recording device via a terminal 105, and this signal is amplified in an amplifier 106. A recording amplifier 107 is connected to the input terminal of the amplifier 106, and this recording amplifier supplies a recording current which is constant with respect to frequency to the recording magnetic head 104 via a resistor 108. A high frequency generator is indicated at 109 and is provided to control the erase head 103. Additionally, the high frequency signal is connected to the capacitor 10
This signal is also supplied to the recording magnetic head 104 via the magnetic recording head 104, and this signal is used for bias magnetization. This bias magnetization is necessary in order to reduce the distortion of the information stored on magnetic tape, as is known, and to ensure a high quality recording of the useful signals.

According to FIG. 3, amplifier 106 is configured as an automatic gain control stage. At this time, a control signal is obtained from the magnitude of the effective signal, and this signal is
11 to adjust the amplification degree of the gain control stage 106. The structure and function of the control device will be explained in detail below with reference to FIG. The operation of the automatic gain control stage is roughly as follows. That is, since the degree of amplification increases more or less depending on the magnitude of the input signal, the input terminal of the subsequent amplifier 107 generally has an amplitude large enough to be recorded on the magnetic tape 101. A signal is always obtained.

According to FIG. 4, the valid signal is fed via a connection terminal 105 and a resistor 112 to an amplifier 113 of an automatic gain control stage 106. The output signal of amplifier 113 is then passed to amplifier 10 as shown in FIG.
Reach 7. To automatically control the amplification of stage 106, the output voltage of amplifier 113 is rectified via decoupling resistor 114 and diode 115. Diode 114 dumps the negative half-wave of the signal voltage after resistor 114 to ground. The rectified voltage, ie, the positive half-wave, charges the storage capacitor 117. The voltage developed across capacitor 117 is the control signal for the automatic level control stage;
According to FIG. 3, a control signal for a transistor 118 provided as an operating section 111 is also generated.
The positive control voltage controls the collector current of transistor 118 to increase. As a result, the resistance between the emitter and collector of the transistor 118 becomes low, and the resistance between the resistor 112 and the transistor 118 becomes low.
A voltage division is performed between the collector and emitter of the amplifier 113, and this voltage division has a functional relationship to the magnitude of the output signal of the amplifier 113. Resistor 1 to storage capacitor 117
19 is attached, which resistor together with the capacitor forms a timing element. Timing element, capacitor 1
17 and resistor 119 are used symbolically for the known circuit technology measures which are taken into account in order to obtain a predetermined control time adapted to the possibly occurring acoustic phenomena.

Terminal 1 of the voltage divider 121 is connected to the connection point between the series resistor 112 and the collector-emitter of the transistor 118.
20 is connected, and the slider 12 of this voltage divider
2 is connected to a reference potential (earth). The other terminal 123 of voltage divider 121 is connected to the base of transistor 124, whose collector is connected to the base of transistor 118 and whose emitter is connected to a reference potential.
Transistor 124 is base current biased through resistor 125, so that transistor 124 is always conductive when slider 122 is away from terminal 123 of voltage divider 121. When the transistor 124 is conductive, that is, when the resistance between the collector and emitter is low,
The base of transistor 118 is connected to ground via this collector-emitter, and transistor 118 is always disconnected. As a result, the connection point 119 is connected to the reference potential via a resistor, the value of which is determined by the slider 1 of the voltage divider 121.
It depends on the settings of 22. Since the adjustment of the slider is done manually by the user of the device, the amplifier 11
3 input voltage can be manually adjusted. On the other hand, if slider 122 is in contact with terminal 123 (or is close to terminal 123 in the resistive plane of voltage divider 121), then the bias voltage at the base of transistor 124 drops below the threshold voltage; As a result, transistor 124 is cut off,
That is, there is a high resistance between the collector and emitter, which re-enables the control voltage at the base of transistor 118, and the setting of the voltage divider ratio between series resistor 112 and the collector-emitter of transistor 108 is determined by the enable signal. automatically adjusted depending on the size of the Therefore, the mode of operation "automatic gain control" or "manual gain control" is based on the voltage divider 121
and at the same time, in the case of the "automatic gain control" mode of operation, the degree of amplification can be selected by the user. The actuator 118 and the voltage divider 121 can be similarly utilized depending on the various configurations of the automatic level control stage. Gain control stages with operational amplifiers are also known, in which the amplification degree is determined in a known manner by the selection of the negative feedback resistor. When the invention is applied to such an amplifier, the transistor 118 or the voltage divider 121 is similarly placed in a feedback circuit or in a circuit that influences the amplification.

Furthermore, it is also conceivable to display the selected operation mode to the user by means of an optical signal. This can be done, for example, as follows. This means that the transistor 11 can be
The switch status of transistor 124 is indicated by using the voltage at the base of transistor 8 as a control voltage for a light emitting diode or the like.

It is particularly advantageous to use a voltage divider with a positive logarithmic resistance characteristic as the voltage divider 121, the base of the transistor 124 having a resistance characteristic whose resistance changes significantly with respect to the adjustment stroke of the slider relative to the tap of the voltage divider. connected to the corresponding voltage divider terminal.

The voltage divider may be directly mechanically operable via an adjustment knob on the front panel of the device. However, instead of a mechanical voltage divider, it is also conceivable to use voltage dividers consisting of other components, such as can be implemented, for example, by photoresistors, semiconductor sections, etc. Control of such a non-mechanical voltage divider can be performed using a DC control signal, an optical signal, or the like. With regard to the characteristics of the voltage divider, the terminal 123 and the slider 122 can be connected already after a short adjustment stroke by turning the slider away from the terminal 123.
It is clear that it is advantageous if a large resistance value occurs between the transistors 124 and 124, so that the resistive section between the slider 122 of the voltage divider 121 and the terminal 120 of the gain control stage 106 Effective for adjusting the signal level at the output terminal.

[Brief explanation of the drawing]

Fig. 1 is a schematic block diagram of a circuit device for recording on magnetic tape, Fig. 2 is a diagram showing details of a circuit device for multiplex recording, and Fig. 3 is a recording device for storing effective signals on magnetic tape. FIG. 4 shows an automatic level control stage with a switching device for manual level control. 1...Magnetic tape, 3...Erasing head, 4...
Recording head, 6...amplifier, 7...recording amplifier,
9...High frequency generator.

Claims (1)

[Claims] 1. A recording level variable device that varies the level of a recording signal supplied to the recording head in an apparatus comprising a recording head, an erasing head, and a bias oscillator that supplies a recording bias current and an erasing bias current to each of the heads, respectively. and erase level variable means for varying the level of the erase bias current supplied to the erase head in accordance with the operation of the recording level variable means.