JPH0320883Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording device having a zero point adjuster.

As shown in FIG. 1, a conventional data recorder includes an input level setting variable resistor 2 connected to an input terminal 1, and an input amplifying circuit 3 that amplifies the signal level-adjusted by the level setting variable resistor 2. and,
An FM modulation circuit 4 that converts the signal amplified by the input amplification circuit 3 into a frequency modulated wave (FM wave), an amplifier 5 that amplifies the output of the FM modulation circuit 4, and a record for recording the output of this amplifier 5. It has a recording system consisting of a head 6, a reproduction head 8 for reproducing FM waves from a tape 7, a head amplifier 9 for amplifying the output of the head 8, and a head amplifier 9 for demodulating the output of the amplifier 9 into an analog signal. An FM demodulation circuit 10, a variable resistor 11 that adjusts the level of the output signal of the demodulation circuit 10, an output amplification circuit 12 that amplifies the signal set by the variable resistor 11, and an output terminal 13 that sends out an analog signal. It has a regeneration system consisting of: The magnetic recording/reproducing machine 14 shown surrounded by a dotted line has a pair of reels 15 and 16 for driving the magnetic tape 7.
, Kyabustan 17, pinch roller 18,
It consists of heads 6 and 8. A level display device consisting of a meter amplifier 19 and a meter 20 is also provided to display the level of the signal. This level display device is connected to the output terminal 13 by closing the switch 21 to contact (a) during playback, and is connected to the output terminal 13 by closing the switch 21 to contact (b) during recording. connected to. Further, in order to check the level of the recording circuit, a branch line 22 is provided on the output line of the modulation circuit 4, and a changeover switch 23 is further provided on the input line of the demodulation circuit 10. Therefore, when the switch 23 is turned on to contact (b), the input signal is sent to the meter 20 via the demodulation circuit 10.

The input amplification circuit 3 of the data recorder described above includes an operational amplifier 24 whose one input terminal (+) is connected to the input terminal 1 via the variable resistor 2 and whose output terminal is connected to the modulation circuit 4; A first resistor R1 connected between the other input terminal (-) of the operational amplifier 24 and its output terminal, and a first resistor _R1 connected between the other input terminal (-) of the operational amplifier 24 and the ground line. 2 resistors _R2 . Now, if zero point adjustment is not taken into consideration, the amplification degree of this input amplifier circuit 3 is (R ₁ +R ₂ )/R ₂ .

This data recorder has a variable resistor connected between the positive power supply (+V) and the negative power supply (-V).
Zero point adjuster 25 consisting of VR and a third resistor R ₃ connected between the movable contact of this variable resistor VR and the other input terminal (-) of the operational amplifier 24
is provided. When such a zero point regulator 25 is provided, if the voltage obtained at the contact of the variable resistor VR is now V ₁ , then V _A = V ₁ · R ₂ R ₂ + R ₃ · R ₁
The zero point can be adjusted within the voltage V _A range shown by R ₁ + R ₂ . Such zero adjustment is used for two purposes:

To correct the zero point so that the output voltage is zero when the input voltage is zero. That is, to correct the deflection of the meter 20 to zero when the voltage at the input terminal 1 is zero volts.

To shift or move the zero point in order to record a state in which part or all of this DC component is removed when a DC component is superimposed on the input signal.

For the purpose of the above section, this zero point adjuster 25 sets the zero point to -100% and + of the meter 20.
It is configured so that it can be shifted up to 100%.

Similarly to the input amplifier circuit 3, the output amplifier circuit 12 in the reproduction system also includes an operational amplifier 26 and a first resistor.
Similarly to the input side _zero point adjuster ₂₅ , the output side zero point adjuster 27 also consists of a variable resistor VR and a third resistor _R3 . In addition, the output side amplifier circuit 12 and zero point adjuster 2
7 has a similar function to these on the input side.

Incidentally, a data recorder is generally configured to have multiple channels as shown in FIG. Therefore, it has a plurality of input terminals 1 and a plurality of output terminals, and a plurality of zero point adjusters 2 on the input side and the output side.
5,27. In order to accurately adjust the zero point, a multi-rotation variable resistor VR as shown in FIG. 3 is used for the zero point adjusters 25 and 27. The variable resistor VR consists of a threaded operator 28, a movable contact 29 that follows the movement of the operator 28, and a linearly extending resistor 30 that is in contact with the movable contact 29. Then, operator 28
Contact 2 by rotating it with a screwdriver etc.
9 moves forward or backward linearly, and the resistance value changes. In order to accurately change the resistance value over a wide range, it is configured such that the minimum or maximum value is not reached unless the operator 28 is rotated, for example, 16 to 22 times. Therefore, it is virtually impossible to know the resistance value based on the rotation angle position of the screw type operator 28.

Therefore, when the user operates the zero point adjusters 25 and 27 according to the characteristics of the recording or reproduction signal,
Since there is no guideline for zero point shift, it is necessary to use the meter 20 or an external measuring device to perform highly accurate adjustment by rotating the screw type operator 28 as shown in FIG. 3 multiple times. For this reason, the zero point adjustment work is troublesome and the time required for the adjustment becomes long.

Therefore, an object of the present invention is to provide a magnetic recording device that can easily perform zero point adjustment.

To achieve the above object, the present invention includes an input amplifier circuit coupled to an input terminal to which an input signal for recording is supplied, and an input amplifier circuit for converting the input signal into a signal compatible with magnetic recording. a recording circuit, such as the modulation circuit 4 of the embodiment, coupled to a magnetic recording device, and a magnetic recording machine for recording a signal supplied from the recording circuit on the recording medium by a relative scanning motion between the recording medium and a magnetic head. and a zero point adjuster coupled to the input amplifier circuit, and the zero point adjuster adjusts the output voltage of the input amplifier circuit to zero when the voltage of the input signal supplied to the input terminal is zero. a zero point adjustment circuit that can be adjusted to a value in a predetermined range including the zero point adjustment circuit; and a predetermined value that the output voltage of the input amplifier circuit does not include zero when the voltage of the input signal supplied to the input terminal is zero. Alternatively, a magnetic recording comprising a zero point shift circuit set to a value within a predetermined range, and a selection switch selectively connecting the zero point adjustment circuit and the zero point shift circuit to the input amplifier circuit. It is related to equipment.

According to the present invention, since the zero point shift circuit is provided, when the zero point shift circuit is selected by the selection switch, a predetermined zero point shift can be performed. Therefore, the zero point shift can be performed easily and quickly.

Embodiments of the present invention will be described below with reference to the drawings. However, since the symbols 1 to 27, R ₁ to R ₃ , and VR in FIGS. 4 to 6 are substantially the same as those indicated by the same symbols in FIG. 1, the explanation thereof will be omitted.

The external appearance of the data recorder according to the embodiment of the present invention is as shown in FIG. 2, and the electric circuit is formed as shown in FIG. 4. The data recorder in FIG. 4 has zero point adjusters 25, 27 on the input side and output side, as in FIG. 1, but the internal configurations of the zero point adjusters 25, 27 are different. That is, each zero point adjuster 25, 27 is a zero point adjusting circuit consisting of a third resistor _R3 and a variable resistor VR, as shown in FIG. In addition to having a shifting circuit, it has a first zero point shift circuit consisting of a fourth resistor _R4 dedicated to zero point shifting, and a second zero point shift circuit consisting of a fifth resistor _R5 . There is. More specifically,
A selection switch s with three contacts n, a, b is provided, a fourth resistor R ₄ is connected between the negative power supply -V and contact a, and a fifth resistor R ₅ is connected to the positive power supply +V and contact b, and the variable resistor VR
is connected to the contact n, and the common terminal of the switch s is connected to the operational amplifier 24, via the third resistor _R3 .
It is connected to the inverting input terminal of 26.

Further, the value of the fourth resistor _R4 and the voltage value of the power supply -V are such that when the switch s selects the contact a, the output voltage becomes -1V, which is the minimum allowable value, even if the input voltage is zero. The meter 20 is set semi-fixed so that the deflection is -100%, while the fifth resistor
The value of _R5 and the voltage value of the power supply +V are such that when switch s selects contact b, the output voltage will be the maximum allowable value of +1V even if the input voltage is zero, and the swing of the meter 20 will be +100%. It is set semi-fixed like this.

Therefore, the shift of the zero point to -1V (-100%) is
The process is completed by simply switching the switch s to contact a without operating the variable resistor VR as in the conventional case. Similarly, shifting the zero point to +1V (+100%) is completed by simply switching switch s to contact b. Furthermore, ±
Shifts other than the 1V (±100%) shift are performed by operating the variable resistor VR as in the case of FIG.

As is clear from the above, this embodiment has the following advantages.

(b) If the characteristics of the input and output signals are known in advance, the zero point can be shifted by simply turning switch s on contact a or b, without performing zero point shift or zero point correction using the variable resistor VR. , the zero point shift can be easily, quickly and accurately achieved.

(b) Since the zero point shift circuit is set to ±1V, which is the maximum and minimum allowable input/output voltage, it is possible to record and reproduce most signals without having to shift the zero point with the variable resistor VR. become.

Next, a zero point adjuster for a data recorder according to another embodiment of the present invention shown in FIG. 5 will be described.
In this embodiment, two switches S ₁ and S ₂ are used to obtain three zero positions. That is, as shown in FIG. 5, when two switches _S1 and _S2 are connected to contact n, the amplifier 2
4 is connected to a variable resistor VR via a resistor _R3 . However, in this embodiment, the zero point can only be shifted or corrected by ±10% (±0.1V) using the variable resistor VR, the positive and negative power supplies +V and -V, and the third resistor _R3 . It is configured as follows.
Therefore, regardless of the position of the contact of the variable resistor VR, the zero point is placed within a range of ±10% around the zero position of the meter 20 as shown in FIG. For this reason, the variable resistor VR is hardly used for zero point shifting, and is mainly used to obtain an accurate zero point.

When the first switch S ₁ and the second switch S ₂ are linked and the contact b is turned on, the third resistance R ₃
and the fourth resistor R ₄ connect the amplifier 24 and the negative power supply -V
A variable resistor VR is connected in parallel to the fourth resistor _R4 . For this reason, the fourth
As in the case shown in the figure, the zero point can be shifted by -1V (-100%), and the voltage can be shifted by approximately ±0.1V around -1V.
The zero point can be corrected by the variable resistor VR.

On the other hand, when switches S ₁ and S ₂ are connected to contact b, the third resistor R ₃ and the fifth resistor R ₅ are connected to the amplifier 2.
4 and the positive power supply +V, and a variable resistor VR is connected in parallel to the fifth resistor _R5 . Therefore, as in the case of Figure 4, the zero point is +
It is possible to shift 1V (+100%) and +
The zero point can be corrected by approximately ±0.1V around 1V using the variable resistor VR.

As is clear from the above, according to this embodiment, the zero point is -90 to -110%, -10 to +10%, and +
It becomes possible to set it in three ranges from 90 to +110%, and it becomes possible to accurately obtain the zero points of -100%, 0%, and +100% by adjustment. Although the amplifier circuit and zero point adjuster on the reproduction output side are not shown in FIG. 5, they are constructed in the same way as on the recording side.

FIG. 6 shows yet another embodiment of the present invention. In this embodiment, the variable resistor VR is semi-fixed after zero point adjustment. Also the third resistor R ₃
is connected between the contact n of the switch S and the contactor, and a variable resistor 31 is connected between the switch S and the amplifier 24, and this variable resistor 31 is designed to be able to correct the zero point by approximately ±10%. is set to . Therefore, in the zero point adjustment circuit consisting of the variable resistor VR, the third resistor _R3 , and the variable resistor 31,
The zero point can be corrected within a range of ±10% using the variable resistor 31, and the zero point can be accurately set at the 0% position.
When switch S is turned on to contact a, a first zero point shift circuit is formed consisting of variable resistor 31, fourth resistor _R4 , and negative power supply -V, and the zero point is -1V.
(-100%) shift. In this case as well, since the variable resistor 31 is provided, adjustment can be made to accurately shift the zero point to -1V. When switch S is turned on to contact b, a second zero point shift circuit consisting of variable resistor 31, fifth resistor _R5 , and positive power supply +V is formed, and the zero point is +1V (+100%).
shift. In this case as well, since the variable resistor 31 is provided, adjustment can be made to accurately shift the zero point to +1V.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be further modified. For example, the zero point shift may be performed in more steps. Alternatively, the changeover switch S shown in FIG. 4 may be moved between the third resistor _R3 and the inverting input terminal of the amplifier 24. Further, the second resistor _R2 is formed by a series circuit of two resistors R _A and R _B , and the lower end of the third resistor _R3 is connected to the amplifier 24.
It may be connected between the resistors R A and R B instead of directly connecting it to the inverting input terminal (-) of the resistor R _A and R _B .

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional data recorder.
FIG. 2 is a front view of a data recorder according to an embodiment of the present invention, FIG. 3 is a sectional view schematically showing a variable resistor of the zero point adjuster of FIG. 2, and FIG. 4 is a diagram of the data recorder of FIG. 2. FIG. 5 is a circuit diagram showing the zero point adjuster and amplifier circuit of another embodiment, and FIG. 6 is a circuit diagram showing the zero point adjuster and amplifier circuit of still another embodiment. In the symbols used in the drawings, 1 is the input terminal, 3 is the input amplifier circuit, 4 is the FM modulation circuit,
10 is a demodulation circuit, 12 is an output amplifier circuit, 14 is a magnetic recording/reproducing device, 20 is a meter, 24 is an operational amplifier, 25 is a zero point adjuster, VR is a variable resistor, R ₁ is a first resistor, and R ₂ is a The second resistor, _R3 , is the third resistor.

Claims (1)

[Claims for Utility Model Registration] (1) An input amplifier circuit coupled to an input terminal to which an input signal for recording is supplied, and the input amplifier circuit for converting the input signal into a signal compatible with magnetic recording. a recording circuit coupled to the input amplification circuit; a magnetic recorder for recording a signal supplied from the recording circuit onto the recording medium by a relative scanning motion between the recording medium and a magnetic head; and a magnetic recorder coupled to the input amplification circuit. a zero point adjuster, and the zero point adjuster is configured such that when the voltage of the input signal supplied to the input terminal is zero, the output voltage of the input amplifier circuit is a value in a predetermined range including zero. a zero point adjustment circuit that can be adjusted; and a setting such that when the voltage of the input signal supplied to the input terminal is zero, the output voltage of the input amplifier circuit is a predetermined value not including zero or a value within a predetermined range. 1. A magnetic recording device comprising: a zero point shift circuit; and a selection switch selectively connecting the zero point adjustment circuit and the zero point shift circuit to the input amplifier circuit. (2) A utility model in which the zero point adjustment circuit has an adjustment range capable of changing the output voltage of the input amplifier circuit from its minimum permissible value to its maximum permissible value when the voltage of the input signal is zero. A magnetic recording device according to claim 1. (3) The zero point shift circuit is a circuit that sets the output voltage of the input amplifier circuit to its maximum allowable value or minimum allowable value when the voltage of the input signal is zero. The magnetic recording device according to item 1 or 2. (4) The zero point adjustment circuit is a circuit that can adjust the output voltage of the input amplifier circuit within a range near the zero point, and the zero point shift circuit adjusts the output voltage of the input amplifier circuit within a predetermined range. 1. The magnetic recording device according to claim 1, which is a circuit capable of performing the following steps. (5) The input amplification circuit includes an operational amplifier whose one input terminal is supplied with an input signal, and a first resistor connected between the other input terminal of the operational amplifier and its output terminal; a second resistor connected between the other input terminal and the ground line, and the zero point adjustment circuit includes a variable resistor connected between a positive power source and a negative power source; and a third resistor connected by the selection switch between the movable contact of the variable resistor and the other input terminal of the operational amplifier, and the zero point shift circuit is connected to the other input terminal of the operational amplifier. Utility model registration claim 1 or 2, which is a fourth resistor selectively connected by the selection switch between the other input terminal or one end of the third resistor and the DC power supply. Or the magnetic recording device according to item 3. (6) The input amplification circuit includes an operational amplifier whose one input terminal is supplied with an input signal, and a first resistor connected between the other input terminal of the operational amplifier and its output terminal; and a second resistor connected between the other input terminal and the ground line, and the zero point adjustment circuit includes a variable resistor connected between the positive power source and the negative power source. , a third resistor connected by the selection switch between a movable contact of the variable resistor and the other input terminal of the operational amplifier, and the zero point shift circuit is connected to the other input terminal of the operational amplifier. a fourth resistor selectively connected by the selection switch between the input terminal of the input terminal or one end of the third resistor and a DC power supply; and a fourth resistor selectively connected to the fourth resistor. The first claim for utility model registration consists of a connecting switch.
The magnetic recording device described in Section 1.