JPH0132195Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a tape speed reference circuit that generates a voltage that serves as a reference for the running speed of a tape.

[Background and conventional technology]

When controlling the tape running speed in a so-called tape running device such as a tape recorder or tape winding device, a tape speed reference circuit generates a voltage that serves as a reference for the tape running speed and determines the tape running speed. ing.

First, in order to explain the relationship between the voltage output from the tape speed reference circuit and the tape running speed, the basic configuration of a tape running device is shown in FIG.

A magnetic tape 1 is supplied from a supply reel 2 and wound onto a take-up reel 3. The supply reel 2 is rotationally driven by a supply reel motor 4, and the take-up reel 3 is rotationally driven by a take-up reel motor 6 driven by a constant current source 5 or the like. Reference numeral 7 denotes a measuring roller that rotates as the magnetic tape 1 runs, and a slit plate 8 is provided coaxially therewith. A large number of slits 9 are provided on the circumference of the slit plate 8, and the running of the magnetic tape 1 is detected by receiving the light emitted from the light emitting element 10 with a light receiving element 11 provided below the slit plate 8. be able to.

That is, the period of the output signal of the light receiving element 11 corresponds to the running speed of the magnetic tape 1, and the period of the output signal of the light receiving element 11 corresponds to the running speed of the magnetic tape 1.
1 is input to the frequency-voltage conversion circuit 12, a voltage corresponding to the running speed of the magnetic tape 1 can be obtained. Reference numeral 13 denotes a tape speed reference circuit which generates a reference voltage for the magnetic tape 1. 14 is a motor drive amplifier that drives the supply reel motor 4.

Next, the tape speed control operation of the tape running system shown in FIG. 1 will be briefly described.

The take-up reel motor 6 rotates with a substantially constant torque regardless of the rotational speed, and the running speed of the magnetic tape 1 is determined only by the amount of feed of the supply reel 2 due to the rotation of the supply reel motor 4.

Now, when a voltage serving as a reference for the running speed of the tape 1 is generated from the tape speed reference circuit 13, the motor drive amplifier 14 controls the output voltage of the frequency-voltage conversion circuit 12 and the output voltage of the tape speed reference circuit 13 to become zero. , operates to rotate the supply reel motor 4.

Therefore, if the output voltage of the tape speed reference circuit 13 is low, the running speed of the tape 1 decreases, and if it is high, the running speed of the tape 1 increases.

[Conventional technology]

Regarding the conventional tape speed reference circuit, see, for example, Patent Application Publication No. 55-70975 or Patent Application Publication No.
56-26904 etc.

A conventional tape speed reference circuit is schematically shown in FIG. Its basic configuration is an integrating circuit including an operational amplifier 15, a capacitor 16, resistors 17 and 18, etc. When the negative power supply 19 is connected by closing the switch 20, the voltage at the output terminal 21 increases.
If the positive power source 22 is connected by closing the switch 23, the voltage at the output terminal 21 will drop.

FIG. 3 shows changes in the voltage at the output terminal 21.

In FIG. 3, the voltage at the output terminal 21 is plotted on the vertical axis, and time is plotted on the horizontal axis. First, switch 20 is closed from time T0 to T1, and switch 2 is closed from time T1 to T2.
0, 23 and switch 2 from time T2 to T3
3, and from time T3 to T4, switch 23 is closed.
If the capacitor 16 is opened and both ends of the capacitor 16 are short-circuited by means not shown at time T4, a substantially trapezoidal voltage change can be obtained. At this time, the running speed of the tape 1 is approximately proportional to the voltage shown in FIG.

[Issues with conventional technology]

In the conventional tape speed reference circuit as described above, even if the speed reference voltage shown in FIG. 3 is the same when the diameter of the supply reel is large and small as shown in FIG. were different. This is because there is a limit on the overall gain of the tape speed control system, and there is also a limit on the power of the supply reel motor and motor drive amplifier, which causes an error with respect to the speed reference voltage.

This phenomenon in which the actual tape speed differs as the diameter of the supply reel changes has caused the inconvenience that even when running the same tape length, the running time varies depending on the diameter of the supply reel.

[Purpose of this invention]

An object of the present invention is to provide a tape speed reference circuit that keeps the tape running speed constant even if the diameter of the supply reel changes.

[Means for Solving the Problems] The means for solving the above-mentioned problems in the present invention is to detect the diameter of the supply reel and correct the voltage that serves as a reference for the tape speed based on the diameter of the supply reel. It is.

[Structure of the present invention]

The configuration of the present invention includes a voltage setting circuit that sets the running speed of the tape, a reel diameter detection circuit that generates a voltage according to the diameter of the supply reel, and an addition that adds the outputs of the voltage setting circuit and the reel diameter detection circuit. a circuit, an integrating circuit, a comparing circuit that compares the output of the integrating circuit and the output of the adding circuit, and a control section that is controlled by the output of the comparing circuit and sets an upper limit of the output voltage of the integrating circuit. configured.

[Operation of the present invention]

Next, the operation of the present invention will be explained. First, the maximum speed of the tape is approximately determined by the set voltage of the voltage setting circuit. The output of the reel diameter detection circuit, which generates a voltage according to the diameter of the supply reel, corrects the set voltage of the voltage setting circuit according to the diameter of the supply reel.The output of the voltage setting circuit and the output of the reel diameter detection circuit is input to the adder circuit.

The integrating circuit generates a so-called ramp voltage, in which the voltage gradually increases or decreases over time, and the acceleration or deceleration of the tape speed is
Follows the slope of the lamp voltage output from the integrating circuit.

The output voltage of the integrating circuit and the output voltage of the above-mentioned adding circuit are compared by a comparison circuit. That is, the voltage of the output of the integrating circuit increases or decreases as time passes, and the voltage of the comparator circuit is determined by the magnitude of the output voltage of the integrating circuit with respect to the output voltage of the adding circuit.

The comparison circuit drives a control section that sets the upper limit voltage of the integration circuit.

As a result of the above-described operation, the upper limit voltage of the integrating circuit changes depending on the diameter of the supply reel, so even if the diameter of the supply reel changes, the running speed of the tape can be kept constant.

[Example of the present invention]

Next, a detailed explanation will be given of an embodiment of the present invention.

FIG. 4 is a block diagram showing the main parts of an embodiment of the present invention.

25 is a voltage setting circuit for setting the running speed of the tape.

26 is a reel diameter detection circuit that generates a voltage according to the diameter of the supply reel. The outputs of the voltage setting circuit 25 and the reel diameter detection circuit 26 are added by an adding circuit 27, and the output of the adding circuit 27 becomes one input of the comparing circuit 28.

29 is an integrating circuit. The output of the integrating circuit 29 becomes the other input of the comparing circuit 28. Comparison circuit 2
The output of 8 is used by a control section 30 to set the upper limit of the output voltage of the integrating circuit 29.

FIG. 5 shows the configuration of the reel diameter detection circuit.

30 is a signal corresponding to the rotation of a supply reel (not shown) (the faster the supply reel rotates, the shorter the period;
This is an input terminal to which a signal with a long period (if the rotation is slow) is input.

Reference numeral 32 denotes a reset input terminal to which a reset signal for returning a counter and the like to an initial state, which will be described later, is input.

Reference numeral 33 denotes an output terminal that outputs a DC output voltage according to the supply reel based on the signals input to the input terminals 30, 31, and 32.

34 and 35 are AND circuits, and 36 is a counter.

37 is a counter with parallel output of counting results, and 38 is a digital-to-analog converter for converting digital values into analog voltages.

A reset signal input to reset input terminal 32 resets counters 36 and 37. The input terminals 30 and 31 are connected to AND circuits 34 and 31, respectively.
The output signal of a counter 36, which normally outputs a logic "1" and becomes a logic "0" upon completion of counting, is connected to one end of the counter 35 and to the other input terminals of the ANDs 34 and 35. The outputs of the AND circuits 34 and 35 are connected to the inputs of counters 36 and 37, respectively, and the count value of the counter 37 is input to a digital-to-analog conversion circuit 38.

Next, in FIG. 6, the voltage setting circuit 25 shown in FIG.
and the configuration of the adder circuit 27.

The voltage setting circuit 25 includes an input terminal 39 connected to a constant voltage source (not shown), a resistor 40, and an operational amplifier 4.
It consists of 1 etc.

Output of voltage setting circuit 25 and reel diameter detection circuit 2
The outputs of 6 are connected to the inputs of an adder circuit 27, respectively. The adder circuit 27 includes input resistors 42 and 43, an operational amplifier 44, and a resistor 45.

Next, the integrating circuit 29 shown in FIG. 4 will be explained.

The integrating circuit includes operational amplifiers 46, 47, 48, resistors 49, 50, 51, 52, 53, 54, 56,
Diodes 5, 58, 59, capacitor 60, stop switch 61, polarity switch 6
2, a start switch 63, etc. A voltage source is connected to the input terminal 64, and 65
is a voltage source.

First, a voltage source 65 of approximately 1V is connected to the inverting input terminal of the operational amplifier 47 and to the non-inverting input terminal of the operational amplifier 47. Operational amplifier 47
The output of the operational amplifier 48 is connected to the inverting input terminal of the operational amplifier 48, and the non-inverting input terminal of the operational amplifier 48 is grounded via the resistors 52 and 53. A polarity changeover switch 62 is provided, one end of which is connected to an input terminal 64 that is connected to a voltage source that does not operate.

The output of the operational amplifier 48 is sent to the start switch 63
Furthermore, a diode 59 and a resistor 55, and a diode 58 and a resistor 56 are connected in series and connected to the inverting input terminal of the operational amplifier 46.

A resistor 49, a stop switch 61, and a diode 5 are connected between the non-inverting input and the output of the operational amplifier 46.
7, a capacitor 60 and a control section 30, which will be described later, are each connected in parallel.

The output of the integrating circuit 29, ie, the output of the operational amplifier 46, is input to one side of the comparing circuit 28.

The comparison circuit 28 includes an operational amplifier 66 and resistors 67, 6.
The output of the adder circuit 27 is connected to the inverting input of the operational amplifier 66 via the resistor 67, and the output of the integrating circuit 29 is connected to the non-inverting input of the operational amplifier 66.

The output of the comparison circuit 28 is connected to the control section 30. The control unit 30 is made up of a light emitting diode 69 and a phototransistor 70, one end 71 of the light emitting diode 69 is connected to a power supply, and the other end is connected to the output of the comparison circuit 28 via a resistor 72. Further, the phototransistor 70 is connected to the output terminal and the inverting input terminal of the operational amplifier 46 of the integrating circuit 29, to which a resistor 76 is connected in series.

The output of the integrating circuit 29 is connected to an output terminal 74 for a tape speed reference voltage via a diode 73, and the output terminal 74 is connected to a low speed reference voltage source 75, a low speed switch 77, and an operational amplifier 78 via a diode 79. connected via.

Next, the operation of the embodiment of the present invention will be explained.

First, the operation of the reel diameter detection circuit shown in FIG. 5 will be explained.

When a reset signal is first input to the reset terminal 32, the counters 36 and 37 return to zero, and since the parallel output of the count value of the counter 37 also becomes zero, the output of the digital-to-analog converter 38 also becomes zero. At that time, the output of the counter 36 is logic "1"
If we consider ANDs 34 and 35 as gates, the gates are in an open state. When the tape (not shown) starts running, a signal corresponding to the rotation of the supply reel is input to the input terminal 30, a signal corresponding to the rotation of the measuring roller, that is, the running length of the tape is input to the input terminal 31, and the counter 36
and 37 start counting. When the counter 36 finishes counting, the logical product 34,3
5 the gate is closed and counters 36 and 3
7 stops counting and holds the current count value.

Digital to analog converter 38 is counter 3
Convert the count value of 7 to DC voltage. Therefore, a DC voltage corresponding to the diameter of the supply reel is outputted to the output terminal 33.

Next, the operations of the voltage setting circuit 25 and the adding circuit 27 will be explained with reference to FIG.

The voltage setting circuit 25 divides the voltage of the voltage source connected to the input terminal 39 using a resistor 40 . The adding circuit 27 adds the outputs of the reel diameter detection circuit 26 and the voltage setting circuit 25.

Next, the operation of the integrating circuit 29 will be explained with reference to FIG.

In the initial state, the polarity changeover switch 62
And the start switch 63 is open. Also, the stop switch 61 is closed. When the stop switch 61 is opened in this state, the operational amplifier 4
The output of 6 is the forward voltage of diode 57 (approximately 0.5
~0.8V). Since the voltage source 65 is approximately 1V, the output of the operational amplifier 47 is also a positive voltage. Next, the polarity changeover switch 62 and the start switch 63 are closed simultaneously. The voltage of the positive voltage source connected to the input terminal 64 is sufficiently higher than the initial voltage of the operational amplifier 47, and since the output of the operational amplifier 48 is subjected to positive feedback by the resistor 54, it immediately becomes positive. The voltage increases to the limit voltage in the direction, and charges the capacitor 60 via the diode 58 and the resistor 56. As a result, the output of the operational amplifier 46 gradually becomes a negative voltage, and as described later, the maximum voltage is actually determined, but unless there are other restrictions, the output voltage becomes the negative maximum voltage. reach.

At that time, the output voltage of the operational amplifier 47 is
An offset is applied by the voltage of 5, but
This voltage is approximately the opposite (that is, positive) of the output voltage of the operational amplifier 46.

Next, open the polarity switch 62. Then, since the inverting input of the operational amplifier 48 is a positive voltage and the non-inverting input is grounded through the resistors 52 and 53, the output of the operational amplifier 48 becomes a negative voltage and is applied to the capacitor 60 via the diode 59 and the resistor 55. is charged with opposite polarity.

Note that when the low speed switch 77 is closed at that time, the output voltage of the output terminal 74 is dominated by the output voltage of the operational amplifier 46 when the output voltage of the operational amplifier 46 is a negative voltage with respect to the output voltage of the operational amplifier 78. Further, if the output voltage of the operational amplifier 78 is more negative than the output voltage of the operational amplifier 46, it is dominated by the output voltage of the operational amplifier 78.

Next, the operation of the comparison circuit 28 will be explained. The comparison circuit 28 compares the output voltage of the addition circuit 27 with the integration circuit 29.
The output voltage of the adder circuit 27 is compared.
If the voltage of the integrating circuit 29 is negative with respect to the output voltage of the comparator circuit 28, the output of the comparator circuit 28 becomes a negative voltage, and if the output voltage of the adding circuit 27 is negative with respect to the output voltage of the integrating circuit 29, The output of circuit 28 will be a positive voltage.

To explain the operation of the control unit 30 in relation to the comparison circuit 28, when the output voltage of the comparison circuit 28 is positive, no current flows through the diode 69, and the comparison circuit 28
When the output voltage of is negative, current flows through the diode 69 via the resistor 72. As a result of current flowing through the diode 69, the transistor 70 becomes conductive, and the capacitor 60 is connected to the resistor 76 and the transistor 7.
discharged through 0.

Next, the overall operation of each component will be explained, focusing mainly on the relationship between the operations between the components.

FIG. 7 shows the relationship between the output voltage of the output terminal 74 of the tape speed reference circuit shown in FIG. 4 and time.
First, in the initial state, the stop switch 61
is closed, the polarity switch 62 is open, the start switch 63 is open, and the low speed switch 77 is open.

At time T0, the stop switch 61 is opened and the polarity changeover switch 62 and start switch 63 are closed.

As a result, the output of the integrating circuit 29 starts to rise to a negative voltage. At the same time, the tape also starts running and its speed is accelerated to follow the rise in voltage.

On the other hand, the reel detection circuit 26 that detects the diameter of the supply reel outputs a voltage according to the diameter of the reel, and together with the output of the voltage setting circuit 25, the addition circuit 26 outputs a voltage corresponding to the diameter of the reel.
7 and one input terminal of the comparison circuit 28 becomes the added voltage.

When the output voltage of the integrating circuit 29 matches the voltage of the adding circuit 27 at time T1 or T1', the control section 3
0 operates, and the output voltage of the integrating circuit 29 is maintained at a constant voltage.

This deviation between T1 and T1' is determined by the reel diameter detection circuit 26.
The voltage of the voltage setting circuit 25 is corrected by. That is, this is because the upper limit voltage of the output voltage of the integrating circuit 29 is different.

Next, at time T2, the polarity changeover switch 62
, and close the low speed switch 77.

The voltage of the integrator circuit 29 starts to fall immediately from time T2, and after time T3 or T3', the voltage of the integrator circuit 29 becomes more positive, but the voltage at the output terminal 74
is maintained at the voltage of voltage source 75 by diodes 73 and 79.

Next, at time T4, the low speed switch 77 is opened, the stop switch 61 is closed, and the start switch 63 is opened. This is the initial state.

[Other embodiments of the present invention]

The present invention is not limited to the embodiments described above, and various other embodiments are possible. For example, although it has been described that the voltage setting circuit 25 is set to a single voltage, if adjustment or switching is performed depending on the thickness or width of the tape, the upper limit of the optimum tape speed can be always set. It can be set.

In addition to the above embodiment, the reel diameter detection circuit 26 may detect the diameter of the reel by using an arm that directly contacts the reel or by transmitting light to the reel. This will make the circuit simpler.

In addition to the reel diameter detection circuit 26 described in the embodiment of the present invention, it is also possible to detect the diameter of the supply reel from the rotation ratio of the supply reel.

Although the adder circuit 28 simply added in the above-described embodiment, it may also perform non-linear addition.
In the above-described embodiment, the integrating circuit 29 has a configuration in which the polarity of the voltage to be integrated can be changed only by opening and closing one switch, but it may be configured as long as it can increase the polarity and decrease it as necessary. Therefore, basically the integrating circuit described in the section of the prior art described above may be used. Furthermore, the operational amplifier 4 of the integrating circuit 29 shown in FIG.
A non-linear element may be inserted between the output terminal of 6 and the inverting input to obtain an arbitrary voltage rise curve.

The control unit 30 does not need to be limited to a light emitting diode and a phototransistor. For example, it may be a relay, and is composed of another light-emitting element (for example, a lamp) and an element whose resistance changes depending on the amount of light (for example, a light-emitting diode and a phototransistor), and the comparison circuit 2
If the gain of 8 is lowered, time T1 in FIG.
T1' can smooth the voltage change at T2.

〔effect〕

As described above, by implementing the present invention, even if the diameter of the supply reel changes, the tape speed reference voltage is corrected according to the reel diameter.
The tape speed can be kept constant, and it is extremely useful if applied to tape running systems where it is necessary to keep the tape speed constant.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the tape running system. DESCRIPTION OF SYMBOLS 1... Tape, 2... Supply reel, 3... Take-up reel, 4... Supply reel motor, 6... Take-up reel motor, 7... Measuring roller, 8... Slit plate. Figure 2 shows a conventional tape speed reference circuit. 15...Operation amplifier, 16...Capacitor, 1
7, 18...Resistor, 19,20...Voltage source. FIG. 3 is a graph of the change in output voltage over time of a conventional tape speed reference circuit, and FIG. 4 is an embodiment of the present invention. 25...Voltage setting circuit, 26...Reel diameter detection circuit, 27...Addition circuit, 28...Integrator circuit, 3
0...Control unit, 61...Stop switch, 62
...Polarity switch, 63...Start switch, 79...Low speed switch, 46, 47, 48,
66, 78... operational amplifier, 65, 75... voltage source, 74... output terminal. FIG. 5 is an explanatory diagram of the reel diameter detection circuit. 30, 31... Input terminal, 32... Reset input terminal, 33... Output terminal, 34, 35... AND circuit, 36, 37... Counter, 38... Digital to analog converter. FIG. 6 is an explanatory diagram of a voltage setting circuit and a comparison circuit. 41 and 44 are operational amplifiers. FIG. 7 is a graph showing the relationship between output voltage and time in the example.

Claims (1)

[Scope of utility model registration request] In a tape speed reference circuit used in a tape running device that runs the tape from a supply reel to a take-up reel while controlling the rotation of the supply reel based on a reference voltage in order to control the running speed of the tape, A voltage setting circuit that sets the running speed of the tape, a reel diameter detection circuit that generates a voltage according to the diameter of the supply reel, an addition circuit that adds the outputs of the voltage setting circuit and the reel diameter detection circuit, and an integration circuit. , comprising a comparison circuit that compares the output of the integration circuit and the output of the addition circuit, and a control section that is controlled by the output of the comparison circuit and sets an upper limit of the output voltage of the integration circuit. tape speed reference circuit.