JPH0638583A - Recording/reproducing apparatus - Google Patents

Abstract

PURPOSE:To realize a constant speed running servo and particularly the easiness in servo control in a reel drive type recording/reproduction apparatus. CONSTITUTION:In a recording/reproduction apparatus, servo means 28 controls the number of revolutions of a motor in reel drive means in such a manner that the running speed of a tape-shaped recording medium becomes equal to a predetermined running speed based on a PWM signal as a servo control signal, converts a pulse width modulation signal into a DC voltage (28a) corresponding to its coefficient of modulation and makes the resistance value variable between an emitter and a collector by applying it between the base and collector of a transistor Q1. And this transistor Q1 is connected to a semi-fixed resistor or a fixed resistor in an adjusting circuit 28c for the number of revolutions or connected in series with the adjusting circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus for a tape-shaped recording medium, and more particularly to a so-called reel drive type recording / reproducing apparatus for controlling a reel rotation speed to run the tape-shaped recording medium at a constant speed. is there.

[0002]

2. Description of the Related Art For example, a recording or reproducing device using a magnetic tape or an open reel tape housed in a tape cassette housing as a recording medium is widely used. In these recording or reproducing devices, a capstan and a pinch roller are usually used. The magnetic tape is run at a constant speed by pressing it against the magnetic tape and controlling the rotation speed of the capstan at a constant speed. A reel drive system is also known in which the capstan and the pinch roller are omitted and the reel itself around which the magnetic tape is wound is driven to rotate at a constant speed.

[0003]

In the reel drive system, when the take-up reel (the reel shaft meshing with the take-up reel) is rotationally driven at a constant speed, the tape winding diameter on the reel gradually changes. As a result, the tape running speed changes. For example, depending on the tape length, the tape running speed at the tape top and the tape running speed at the tape end may change twice or more.

Therefore, even if the same recording medium is used, compatibility cannot be obtained between the reel drive type recording / reproducing apparatus and the capstan type recording / reproducing apparatus which is widely used at present. The reel drive method is not suitable as a recording / reproducing apparatus that requires fidelity in sound quality because the frequency characteristics and the S / N change from the tape top to the tape end due to changes in the tape running speed. . For these reasons, the reel drive type recording / reproducing apparatus has a problem that it is not practical although it has an advantage that the apparatus configuration is simplified by capstanless.

Further, in order to realize the constant speed running of the tape in the reel drive system, it is conceivable to adopt a servo system in which the tape running speed is detected and the reel motor rotational speed is variably controlled accordingly. in this case,
An error signal is obtained according to the difference between the detected tape running speed and a predetermined speed of tape constant speed running, and a reel motor drive voltage corresponding to the error signal is generated to control the motor rotation speed.

For example, as shown in FIG. 13, PW is used as an error signal.
If M (pulse width modulation) signal is supplied, the resistance of this ₁₀
A DC voltage is converted by the modulation factor-voltage conversion circuit 92 by the capacitor C ₁₀ and applied between the base and emitter of the transistor Q ₁₀ via the resistors R ₁₂ and R ₁₃ . Servo output unit 90 that outputs a drive voltage to the reel motor 91
A semi-fixed resistor RV ₁₀ and resistors R ₁₄ , R ₁₅ are provided as a rotation speed adjusting circuit 94 of the reel motor 91.
That is, the combined resistance value of the semi-fixed resistance RV ₁₀ and the resistances R ₁₄ and R ₁₅ is converted into the motor rotation speed. In addition, semi-fixed resistor R
The resistance value of V ₁₀ is adjusted by, for example, an adjusting operation in the manufacturing stage so as to compensate for the characteristics and variations of the reel motor 11 and each part of the circuit and obtain the reference motor rotation speed by the drive voltage output.

The transistor Q ₁₀ is connected in series with the semi-fixed resistor RV _10, for example, and the resistance value between the emitter and collector of the transistor Q ₁₀ is a direct current applied between the base and the emitter. It changes depending on the voltage value. That is, the resistors R ₁₂ , R ₁₃ and the transistor Q ₁₀ function as the voltage-resistance value conversion unit 93. Therefore,
A change in the combined resistance of the resistor R ₁₅ and the transistor Q ₁₀ appears in the change in tape speed, that is, the rotation speed of the reel motor is controlled based on the PWM signal as an error signal.

However, in such a system, the element sensitivity of the transistor Q ₁₀ becomes too high, and a slight fluctuation of the PWM signal causes a large change in the motor rotation speed. Therefore, in the servo system, the PWM signal There is a problem that the circuit configuration becomes difficult because the stability of the amplitude and the modulation rate is strictly required. Similarly, due to the high element sensitivity, external noise that has penetrated into the base of the transistor Q ₁₀ causes the motor rotation speed to fluctuate, and the temperature characteristic of the transistor Q ₁₀ is also susceptible to the influence. Also, PW
There is also a problem that the modulation rate of the M signal and the rate of change of the motor rotation speed are not linear, and control is difficult. For these reasons, even if an attempt is made to realize constant speed running by adding a rotary servo mechanism to the reel motor in the reel drive system, it has been difficult to put it into practical use.

[0009]

In view of the above problems, the present invention provides a reel drive type recording or reproducing apparatus for recording / reproducing by running a tape-shaped recording medium at a constant speed. The purpose is to realize easy servo control.

That is, in a recording or reproducing apparatus for recording or reproducing information on or from a tape-shaped recording medium wound on a reel, a reel drive for rotating the reel to execute the traveling operation of the tape-shaped recording medium. Means, servo control means for detecting the traveling speed of the tape-shaped recording medium, and outputting a pulse width modulation signal for controlling the number of rotations of the motor in the reel drive means according to the traveling speed, and tape-shaped means for controlling the tape width based on the pulse width modulation signal. Servo means for controlling the number of rotations of the motor in the reel drive means is provided so that the traveling speed of the recording medium becomes a predetermined traveling speed. In particular, the servo means includes a conversion circuit for converting the pulse width modulation signal output by the servo control means into a DC voltage according to the modulation rate, and a semi-fixed resistor for adjusting the motor rotation speed in the reel drive means. With the adjusting circuit and the transistor that is connected in parallel to the semi-fixed resistor in the adjusting circuit and whose direct-current voltage output from the conversion circuit is applied between the base and collector to change the resistance value between the emitter and collector. Constitute.

Alternatively, the servo means includes a conversion circuit for converting the pulse width modulation signal output by the servo control means into a DC voltage corresponding to the modulation rate, and a semi-fixed circuit for adjusting the motor rotation speed in the reel drive means. The resistance value between the emitter and collector by connecting the adjustment circuit having a resistor and a fixed resistor in parallel with the fixed resistor in the adjustment circuit and applying the DC voltage output from the conversion circuit between the base and collector. Is composed of a variable transistor.

Further alternatively, the servo means includes a conversion circuit for converting the pulse width modulation signal output by the servo control means into a DC voltage according to the modulation rate, and a semi-fixed resistor for adjusting the motor rotation speed in the reel drive means. And a transistor having a resistance value between the emitter and the collector that is variable by applying a DC voltage output from the conversion circuit between the base and the collector and connected in series to the adjustment circuit.

Further, in the servo means having these configurations, by making the input resistance value to the transistor variable, it is possible to change the response of the servo operation with respect to the motor rotation speed in the reel drive means.

[0014]

With the above construction, the number of rotations of the reel (reel shaft for driving the reel) is controlled so that the tape running speed becomes constant from the tape top to the tape end, and the sensitivity of the transistor in the servo means is controlled. Can be made smaller. Further, the modulation rate of the PWM signal and the rate of change of the motor rotation speed are improved linearly.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 4 is a block diagram showing a reel servo system of the recording or reproducing apparatus of the present invention. Reference numeral 1 denotes a magnetic tape wound and housed on a supply reel 2 and a take-up reel 3 in a tape cassette, which is loaded into the recording or reproducing apparatus of the embodiment and is run, so that the magnetic head 10 causes audio information and the like. The recording / reproducing operation is performed.

The running of the magnetic tape 1 is performed by driving the take-up reel 3 by the reel motor 11. That is, as shown in FIG. 5, the rotational force of the reel motor 11 is transmitted to the flywheel 13 by the belt 12, and the drive shaft 14 provided on the flywheel 13 rotates. A take-up reel stand 15 is pressed against the drive shaft 14 via a rubber belt 16 on its peripheral surface, and the take-up reel stand 15 is rotated by the rotation of the drive shaft 14, and the reel mounted on the take-up reel stand 15 is rotated. The drive shaft 17 rotates.

When the tape cassette 4 is loaded as shown by the alternate long and short dash line, the hub of the take-up reel 3 meshes with the reel drive shaft 17 so that the hub rotates and the magnetic tape 1 runs. Reference numeral 18 denotes a reel shaft for the supply reel 2.

Reference numeral 12 in FIGS. 4 and 5 denotes a rotary encoder provided to detect the tape traveling speed, and includes a roller 12a, a shield plate 12b provided on the roller 12a, and a photodiode 12 as a light output section.
c, a phototransistor 12d for detecting an optical output from the photodiode 12c and converting it into an electric signal.

The structure of the rotary encoder 12 is shown in FIG.
As shown in (a), the roller 12a is connected to the frame 12
The photoreflector 1 is rotatably attached to the roller e and includes a photodiode 12c and a phototransistor 12d below the roller 12a and is made into one chip.
2f is mounted on the substrate 12g. Photo-reflector 12f has a window portion 12f ₂ for incident detection light by the window portion 12f ₁ and the phototransistor 12d outputs the light from the photodiode 12c as shown in FIG. 6 (c) are provided.

On the lower surface side of the roller 12a facing the photo reflector 12f, as shown in FIG. 6 (b), the shield plate 1 is provided.
2b is formed, and the angle of the shield plate 12b with respect to the photo reflector 12f changes depending on the rotation position of the roller 12a, so that the light emitted from the photodiode 12c is blocked or made incident on the phototransistor 12d. Eggplant

That is, since the roller 12a and the shielding plate 12b are mounted rotatably with respect to the frame 12e about the shaft portion 12a ₁ as shown in FIGS. 7A and 7B, as shown in FIG. When the roller 12a is pressed against the magnetic tape 1, the roller 12a is rotated as the magnetic tape 1 runs, and the shield plate 12b is also rotated. Here, when the shield plate 12b is in the rotation position of FIG. 7A with respect to the photo reflector 12f, the light from the photodiode 12c output through the window portion 12f ₁ is shielded by the shield plate 12b,
It is not detected by the phototransistor 12d. However, when the shield plate 12b is in the rotation position of FIG. 7B with respect to the photo reflector 12f, the light from the photodiode 12c output through the window portion 12f ₁ is shielded by the shield plate 1b.
The light is not blocked by 2b and enters the phototransistor 12d through the window 12f ₂ .

Therefore, in the phototransistor 12d,
The incidence and non-incidence of light are repeated every 1/4 rotation of the roller 12a.
The detected waveform Sa as shown in (a) is output.
The diameter of the roller 12a is set such that the roller 12a rotates 4 times per second when running at the rated speed (4.76 cm / sec in a compact cassette tape).

In FIG. 4, 20 is a waveform shaping circuit,
The output of the phototransistor 12d with distortion is shaped into a square wave. That is, the output Sa of the rotary encoder 12 of FIG. 8A has a predetermined threshold value having a hysteresis, and the waveform shaping output Sb as shown in FIG. 8B is obtained.

Reference numeral 21 denotes a rotation time measuring unit, which is a roller 12
The time required for one rotation of a is calculated. 1 of roller 12a
The rotation corresponds to the T period in FIG. 8B, that is, the period from the rising (or falling) of the pulse to the rising (or falling) of the pulse two pulses after.

Reference numeral 22 denotes a deviation calculation unit, which holds in advance one rotation cycle information (hereinafter referred to as rated cycle information T ₀₂₅ ) of the roller 12a according to the rated speed of the magnetic tape running. It should be noted that the rated cycle information T ₀₂₅ is 0.25 seconds because the roller 12a makes four revolutions per second when traveling at the rated speed. The deviation d is calculated by using the rated cycle information T ₀₂₅ and the input actual one rotation cycle T. That is,

[Equation 1]

Reference numeral 23 is a gain coefficient generator, which outputs a coefficient K for setting the servo gain. Note that the coefficient K is always 1
In this case, it is not necessary to provide the gain coefficient generating section 23. However, by setting the coefficient K to a predetermined value, the servo gain is set, and the response of the servo operation described later can be set.

Further, by making the output coefficient K variable based on the calculated deviation d, the servo response is changed according to the tape running speed. For example, when the deviation d is large, that is, the tape running speed. The gain coefficient K is increased when the difference between the rated speeds is large, while the gain coefficient K is decreased when the tape running speed is close to the rated speed. As a result, it is possible to accelerate the pulling up to the rated speed and improve the servo stability at the rated speed.

Reference numeral 24 is a control constant generator, which generates a control constant A obtained by a functional expression of a rotation speed range of the reel motor 11 and a servo control value L described later. That is, it is a constant for obtaining the servo control value L that properly matches the variable rotation range of the reel motor, and thus the control constant A is a fixed value for each device. The control constant A is calculated as in the following (Equation 2).

[0029]

[Equation 2] However, N _MAX : Reel motor speed at tape top N _MIN : Reel motor speed at tape end L _MAX : Servo control value at tape top L _MIN : Servo control value at tape end

Reference numeral 25 denotes a control output calculation unit for calculating and outputting the servo control value L _N , and 26 stores the servo control value L _N output from the control output calculation unit 25, and supplies it to a data conversion unit 27 described later. Output storage unit. In the output storage unit 26, the supplied servo control value L _N is stored as the servo control value L, and this servo control value L is fed back to the control output calculation unit 25 as the previous servo control value L _N to obtain the servo control value L _N. Is used for calculation.

In the control output calculator 25, the deviation d
Using the gain coefficient K, the control constant A, and the fed back servo control value L, the current servo control value L _N is calculated as in the following (Equation 3).

[Equation 3]

The data conversion unit 27 converts the servo control value L supplied from the output storage unit 26 into a reference value for servo operation. For example, a resistance value corresponding to the servo control value L,
Convert to voltage value, pulse width, pulse period, etc. In this embodiment, it is assumed that the servo control value L is converted into a PWM (pulse width modulation) signal having "L period" (when "H period" is constant). Therefore, L _MAX and L _MIN used to calculate the control constant A are values corresponding to the pulse width of the “L period” at the tape top and the tape end in the PWM signal.

Reference numeral 28 is a motor servo circuit, for example, a drive for converting the supplied PWM signal into a voltage value (or resistance value) and feeding back the converted voltage value (or resistance value) from the reel motor 11. Servo output E _M is provided to the reel motor 11 so as to match the voltage value (or resistance value), and drive control of the reel motor 11 is performed so as to minimize the deviation d.

In the recording or reproducing apparatus of the present embodiment constructed as described above, the number of rotations of the reel motor 11 is servo-controlled so that the running speed of the magnetic tape 1 is kept substantially constant from the tape top to the tape end. To be done.

That is, in the servo operation of the number of rotations with respect to the reel motor 11, the roller 12a is rotated as the tape runs, and the rotary encoder 12 outputs the rotation speed information Sa.
Is output and the waveform is shaped and output (Sb), the rotation time measuring unit 21 measures one rotation cycle T of the roller 12a. Then, the deviation d is obtained by the deviation calculator 22 as described above using one rotation cycle T, and the control output calculator 2
5 is supplied. The control output calculation unit 25 calculates the current servo control value L _N from the deviation d, the gain coefficient K, the control constant A, and the previous servo control value L, and supplies it to the output storage unit 26 for storage. The stored servo control value L is converted into a PWM signal by the data converter 27, and the motor servo circuit 2
Reference numeral 8 forms a servo output (motor drive voltage output) E _M based on the PWM signal, and controls the drive of the reel motor 11.

By continuing the above operation, the number of rotations of the reel motor 11 is gradually decreased in accordance with the tape traveling position, that is, the winding diameter of the take-up reel 3, so that the tape traveling speed is substantially constant. Kept in.

Therefore, the recording medium such as a compact cassette tape used in the recording / reproducing apparatus of this embodiment is compatible with the recording / reproducing apparatus of the capstan system, and from the tape top to the tape end. A faithful recording / reproducing operation is performed without changing the frequency characteristic or the S / N.

The configuration of the motor servo circuit 28 in this embodiment is shown in FIG. When the PWM signal output from the data converter 27 is supplied, the motor servo circuit 2
In _No. 8, this is converted into a DC voltage by the modulation factor-voltage conversion circuit 28a by the resistor R ₁ and the capacitor C ₁ .
The voltage is applied between the base and collector of the transistor Q ₁ via the resistors R ₂ and R ₃ . Resistance R ₂ , R
₃ and the transistor Q ₁ function as the voltage-resistance value conversion unit 28b.

On the other hand, the reel motor 11 is provided in the servo output section 28d for outputting the drive voltage to the reel motor 11.
A semi-fixed resistor RV ₁ and resistors R ₄ and R ₅ are provided as the rotation speed adjusting circuit 28 c of the above, and the combined resistance value of the semi-fixed resistors RV ₁ , R ₄ and R ₅ is converted into a motor rotation speed and output. It is made to be done. In addition, the semi-fixed resistor RV ₁
The resistance value of is adjusted by, for example, an adjusting operation in the manufacturing stage so that the reference motor rotation speed can be obtained from the drive voltage output by compensating for the characteristics and variations of the reel motor 11 and each part of the circuit.

Here, the transistor Q ₁ is connected to the semi-fixed resistor RV _{1 in} series, that is, in parallel with the resistor R ₅ , and the resistance value between the emitter and collector of the transistor Q ₁ is the base. Since it changes depending on the value of the DC voltage applied between the collectors, the change in the combined resistance due to the resistor R ₅ and the transistor Q ₁ appears in the change in tape speed, that is, the rotation speed of the reel motor 11 is based on the PWM signal. Controlled.

For example, when the PWM signal is supplied as shown in FIG. 2 (a), the modulation rate-voltage conversion circuit 27a operates as shown in FIG.
The DC voltage output of (b) is obtained, which is the transistor Q
The resistance value between the emitter and collector of ₁ is controlled as shown in FIG. The rotation speed of the reel motor 11 is controlled as shown in FIG. 2D by the resistance value between the emitter and collector of FIG. 2C and the combined resistance of the resistor R ₅ .

[0042] When applying a control voltage thus between the base and the collector of the transistor Q _1, the transistor Q ₁
Element sensitivity is reduced, and therefore, restrictions such as the stability of the modulation rate of the PWM signal and the stability of the amplitude are relaxed, and the circuit configuration of the servo system becomes easy. The rotation speed of the reel motor 11 by the temperature characteristics of the noise and the transistor Q ₁ which enters the base of the transistor Q ₁ is also suppressed be affected.

Further, in this case, the linearity between the rotation speed of the reel motor 11 and the PWM signal is improved. In FIG. 3, SV _CB1 and SV _CB2 show the relationship between the tape speed deviation (%) and the PWM modulation rate (%) according to the method of this embodiment, and SV _BE1 and SV _BE2 are the conventional examples (see FIG. 13 above). ) Method is shown. As can be seen from the figure, the linearity is remarkably improved as compared with the conventional example, so that the use range of the duty ratio of the PWM signal is expanded and finer servo control becomes possible.

By the way, SV _CB1 and SV in FIG.
_CB2 is data in which the value of the input resistance R _{2 to} the transistor Q ₁ is changed, that is, as a modification of the present embodiment, by configuring the resistance R ₂ as a variable resistor,
It is possible to provide a recording or reproducing device capable of changing the servo response by adjusting the (variable) resistance R ₂ .

FIG. 9 shows a second embodiment of the present invention, and shows a motor servo circuit 28 as in FIG. In this embodiment, the transistor Q ₁ is connected in parallel with the semi-fixed resistor RV ₁ . Therefore, the combined resistance value of the semi-fixed resistor RV ₁ and the transistor Q ₁ is changed by the DC voltage converted from the PWM signal, and the rotation speed of the reel motor 11 is controlled.

FIG. 10 shows a motor servo circuit 28 according to the third embodiment of the present invention. In this embodiment, the transistor Q ₁ is connected in series with the rotation speed adjusting circuit 28c including the semi-fixed resistor RV ₁ and the resistor R ₄ . Therefore,
The DC voltage converted from the PWM signal causes the resistor R _{4 to}
Then, the combined resistance value of the semi-fixed resistor RV ₁ and the transistor Q ₁ is changed, and the rotation speed of the reel motor 11 is controlled.

FIG. 11 shows a fourth embodiment of the present invention, which is adopted when the rotation speed adjusting circuit 28c is floating from the ground circuit and is used for voltage-resistance conversion. when the DC voltage converted from the PWM signal in the section 28b is applied to the transistor Q _1, and the output of the transistor Q ₁ is the transistor Q ₂
Applied between the base and collector of the transistor Q ₂
This is a method in which the resistance value between the collector and the emitter is controlled. The rotation speed of the reel motor 11 is controlled by the change in the combined resistance value of the transistor Q ₂ and the resistor R ₅ . The same effects as those of the above-described first embodiment can be obtained in the above-described second to fourth embodiments.

By the way, as the configuration example of the servo system which can be adopted in the embodiment of the present invention, the method of calculating the deviation from the roller rotation cycle and executing the servo control based on the deviation has been described, but as shown in FIG. 12, the roller 12a is used. It is also possible to calculate the current traveling position of the magnetic tape 1 from one rotation cycle of the above, calculate the number of rotations of the reel motor 11 from the calculated traveling position, and obtain the servo control value based on this. Even in such a servo system, each of the above embodiments can be adopted in the motor servo circuit.

That is, if the initial value of the motor rotation speed (for example, the rotation speed at which the rated speed is obtained at the tape end) and the reel diameter are known, the current tape winding diameter on the take-up reel 3 can be calculated from the output of the rotary encoder 12. Can be calculated.
Then, the number of rotations of the reel motor 11 for making the running of the magnetic tape 1 the rated speed can be calculated according to the tape winding diameter. This is utilized to perform servo control. 12, the same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 30 denotes a tape position calculating unit, which calculates the tape position T _P by the following (Equation 4).

[Equation 4] Here, R _T : rotation period of the roller 12a (second) T _T : tape thickness of the magnetic tape 1 (mm) v ₀ : rated running speed (mm / sec) T _END : time required from tape top to tape end ( Second) H: Radius (mm) of take-up reel 3 π: Circular ratio (However, this is the value when the reel motor 11 is rotating at the above initial value, and the initial value gives the rated speed at the tape top. If it is a value, T _END = 0)

Reference numeral 31 is a motor rotation speed calculation unit for calculating the rotation speed of the reel motor 11 based on the calculated tape position T _P. The motor rotation speed calculation unit 31 calculates a magnification M with respect to an initial value of the motor rotation speed, and multiplies the magnification M with the initial value to calculate a servo control value L corresponding to the motor rotation speed. The magnification M is obtained by the following (Equation 5).

[0052]

[Equation 5] When the magnification M is obtained, the servo control value L corresponding to the motor rotation speed obtained by multiplying this by the initial value is supplied to the data conversion unit 27 via the output storage unit 26, and the motor servo circuit 28 rotates the rotation speed of the reel motor 11. The servo control signal E _M is output so that the value of Eq.

Even with the above servo system structure, constant speed running control of the magnetic tape is realized in the reel drive system, and the present invention is adopted in the motor servo circuit 28, which facilitates the structure of the servo system. By improving the linearity between the rotation speed of the reel motor 11 and the PWM signal, precise servo control can be realized.

The present invention is applicable to compact cassette tapes, micro cassette tapes, open reel tapes,
The present invention can be widely applied to a recording-only device, a reproduction-only device, a recording / reproducing device, etc. corresponding to a recording medium such as a digital audio tape.

[0055]

As described above, according to the present invention, the servo for controlling the motor speed in the reel drive means is controlled so that the traveling speed of the tape-shaped recording medium becomes the predetermined traveling speed based on the PWM signal as the servo control signal. The means is
After converting the pulse width modulation signal to a DC voltage according to its modulation rate, the DC voltage is applied between the base and collector of the transistor, which is connected in parallel to the semi-fixed resistor in the rotation speed adjustment circuit. The connection is made in parallel with a fixed resistor in the adjustment circuit or in series with the adjustment circuit. Then, the resistance value between the emitter and collector is changed by the DC voltage based on the PWM signal applied between the base and collector of the transistor, so that the resistance value of the adjusting circuit is changed and the reel motor rotation speed is controlled. Is configured.

As a result, the constant speed running control of the tape running can be realized and the element sensitivity of the transistor in the servo means can be reduced, so that the stability of the modulation rate of the PWM signal and the stability of the amplitude are restricted. Becomes loose,
Servo system circuit configuration becomes easy. Further, there is an effect that the number of revolutions of the reel motor can be suppressed from being influenced by noise penetrating into the base of the transistor and temperature characteristics of the transistor.

Further, since the modulation rate of the PWM signal and the rate of change of the motor rotation number are improved linearly, the use range of the duty ratio of the PWM signal is expanded, and more precise servo control can be performed. There is also.

Further, in the servo means having the above structure, by making the input resistance value to the transistor variable, it is possible to change the responsiveness of the servo operation with respect to the motor rotation speed in the reel drive means. The effect also occurs.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a motor servo circuit according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the motor servo circuit of the embodiment.

FIG. 3 is an explanatory diagram of servo characteristics by the motor servo circuit of the embodiment.

FIG. 4 is a block diagram of a servo system according to an embodiment.

FIG. 5 is an explanatory diagram of a reel drive system according to an embodiment.

FIG. 6 is an explanatory diagram of a rotary encoder according to an embodiment.

FIG. 7 is an explanatory diagram of a detection operation of the rotary encoder of the embodiment.

FIG. 8 is an explanatory diagram of output signals of the rotary encoder according to the embodiment.

FIG. 9 is a configuration diagram of a motor servo circuit according to a second embodiment of the present invention.

FIG. 10 is a configuration diagram of a motor servo circuit according to a third embodiment of the present invention.

FIG. 11 is a configuration diagram of a motor servo circuit according to a fourth embodiment of the present invention.

FIG. 12 is a block diagram of another servo system according to the embodiment.

FIG. 13 is a configuration diagram of a conventional motor servo circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetic tape 3 take-up reel 11 reel motor 12 rotary encoder 20 waveform shaping circuit 21 rotation time measurement unit 22 deviation calculation unit 23 gain coefficient generation unit 24 control constant generation unit 25 control output calculation unit 26 output storage unit 27 data conversion unit 28 Motor servo circuit 28a Modulation rate-voltage conversion circuit 28b Voltage-resistance value conversion unit 28c Rotation speed adjustment circuit 28d Servo output unit

Claims (4)

[Claims] 1. A recording or reproducing device for recording or reproducing information on a tape-shaped recording medium wound on a reel, wherein the reel is rotationally driven to execute a traveling operation of the tape-shaped recording medium. Drive means, servo control means for detecting a traveling speed of the tape-shaped recording medium, and outputting a pulse width modulation signal for controlling a motor rotation speed in the reel drive means according to the traveling speed, and an output by the servo control means A conversion circuit for converting the pulse width modulated signal into a DC voltage according to the modulation rate,
An adjusting circuit having a semi-fixed resistor for adjusting the motor rotation speed in the reel drive means, and a DC voltage output from the conversion circuit which is connected in parallel to the semi-fixed resistor in the adjusting circuit and applied between the base and the collector. A transistor having a variable resistance value between the emitter and collector is provided to control the motor rotation speed in the reel drive means so that the tape-shaped recording medium travels at a predetermined travel speed. A recording or reproducing device characterized by comprising a servo means capable of performing. 2. A recording or reproducing apparatus for recording or reproducing information on or from a tape-shaped recording medium wound on a reel, wherein the reel is rotationally driven to execute a running operation of the tape-shaped recording medium. Drive means, servo control means for detecting a traveling speed of the tape-shaped recording medium, and outputting a pulse width modulation signal for controlling a motor rotation speed in the reel drive means according to the traveling speed, and an output by the servo control means A conversion circuit for converting the pulse width modulated signal into a DC voltage according to the modulation rate,
An adjusting circuit having a semi-fixed resistor and a fixed resistor for adjusting the number of rotations of the motor in the reel drive means, a DC voltage which is connected in parallel to the fixed resistor in the adjusting circuit and is output from the conversion circuit is a base. A transistor whose resistance value between the emitter and collector is varied by being applied between the collectors is provided, and the number of rotations of the motor in the reel drive means is adjusted so that the traveling speed of the tape-shaped recording medium becomes a predetermined traveling speed. A recording / reproducing apparatus comprising: a servo unit capable of controlling the. 3. A recording or reproducing apparatus for recording or reproducing information on a tape-shaped recording medium wound around a reel, wherein the reel is rotationally driven to execute a traveling operation of the tape-shaped recording medium. Drive means, servo control means for detecting a traveling speed of the tape-shaped recording medium, and outputting a pulse width modulation signal for controlling a motor rotation speed in the reel drive means according to the traveling speed, and an output by the servo control means A conversion circuit for converting the pulse width modulated signal into a DC voltage according to the modulation rate,
An adjusting circuit having a semi-fixed resistor for adjusting the motor speed in the reel drive means, an emitter connected by being connected in series to the adjusting circuit and applying a DC voltage output from the converting circuit between a base and a collector. .Transistors with variable resistance between collectors,
And servo means for controlling the number of rotations of the motor in the reel drive means so that the traveling speed of the tape-shaped recording medium becomes a predetermined traveling speed. Recording or playback device. 4. The responsiveness of the servo operation to the number of rotations of the motor in the reel drive means can be changed by changing the input resistance value to the transistor. Alternatively, the recording or reproducing apparatus according to claim 2 or claim 3.