JPH0636401A - Recording or reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a reel drive type recording or reproducing device for recording / reproducing by running a tape at a constant speed, and further to eliminate servo deviating due to an error in tape traveling speed detection. [Structure] A deviation d with respect to a predetermined running speed of the tape is calculated from the tape running speed information T detected by the tape running speed detecting means 12, 20, 21 (22), and deviations n times in the past (d _{1 to} d _5). ) Part or all of the average value d _AV is calculated (32, 33, 34), and the average value d _{AV
The AV} is used to calculate the servo control value L (25).

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, a system in which the tape running speed is detected and the rotation speed of the reel motor is servo-controlled is conceivable. Vibration, momentary fluctuation of operating voltage, or uneven thickness of magnetic tape,
Due to the influence of wrinkles, etc., the tape running speed is not always detected accurately, and there is a problem that the rotation servo of the reel motor is easily released due to an error in the tape running speed detection. It was difficult to realize driving.

[0006]

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, and further, , It is an object of the present invention to eliminate the occurrence of a rotation servo deviation of the reel motor due to an error in the tape running speed detection.

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 a running operation of the tape-shaped recording medium. Means, a tape running speed detecting means having a roller that is pressed against the tape-shaped recording medium and rotates as the tape-shaped recording medium runs, and the rotation cycle of the roller is measured, and the measured value is used to measure the tape-shaped recording medium. Deviation calculating means for calculating the deviation with respect to the predetermined traveling speed, deviation storing means capable of holding the deviation of the past n times including the calculated present deviation, and one of the deviations stored in the deviation storing means. Proportional to the number of rotations of the motor in the reel drive means by using an average value calculating means for calculating the average value of all or all parts and the average value output from the average value calculating means Servo control value calculating means for calculating a servo control value, and a motor in the reel drive means so that the traveling speed of the tape-shaped recording medium becomes a predetermined traveling speed based on the servo control value calculated by the servo control value calculating means. Provided is a recording or reproducing device having a servo unit capable of controlling the rotation speed.

In addition to the above configuration, a switching means for selectively outputting the average value output from the average value calculating means and the deviation calculated by the deviation calculating means, and the number of deviations stored in the deviation storing means. And a switching control means for performing switching control of the switching means according to the above, and the servo control value calculation means calculates the servo control value using the deviation or the average value of the deviation.

[0009]

With the above structure, the number of rotations of the reel (reel shaft for driving the reel) is controlled so that the tape traveling speed becomes constant from the tape top to the tape end. Further, by calculating the servo control value based on the average value of a part or all of the calculated deviations for the past n times, it is possible to cancel the error due to the influence of disturbance or the like that may occur on the deviation. it can.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing a main part of a 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 magnetic tape 1 is run by driving the take-up reel 3 by a reel motor 11. That is, as shown in FIG. 3, 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 indicated by the one-dot chain 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. 1 and 3 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 is window 12f ₂ for detecting light incident by the window 12f ₁ and the phototransistor 12d outputs the light from the photodiode 12c is provided as shown in FIG. 4 (c).

As shown in FIG. 4B, the shield plate 1 is provided on the lower surface side of the roller 12a facing the photo reflector 12f.
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, as shown in FIGS. 5A and 5B, the roller 12a and the shielding plate 12b are mounted rotatably with respect to the frame 12e about the shaft portion 12a ₁ , so that 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. 5A 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 shielding plate 12b is in the rotation position of FIG. 5B with respect to the photo reflector 12f, the light from the photodiode 12c output through the window 12f ₁ is emitted from the shielding 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. 1, reference numeral 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. 6A has a predetermined threshold value having a hysteresis, and the waveform shaping output Sb as shown in FIG. 6B 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 period T in FIG. 6B, 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 section, 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. This rated cycle information T ₀₂₅ and the input actual 1
The deviation d is calculated using the 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 to a desired value, and the response of the servo operation described later can be set.

Further, the coefficient K to be output is made variable on the basis of the calculated deviation d (the average value d _AV of the deviation d which will be described later), thereby changing the servo response in accordance with the tape running speed. When the deviation d (d _AV ) is large, that is, when the difference between the tape running speed and the rated speed is large, the gain coefficient K is increased. On the other hand, when the tape running speed is close to the rated speed, the gain coefficient K is decreased. To do. 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).

[0024]

[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 a 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 to perform servo control. It is used to calculate the value L _N.

In the control output calculator 25, the deviation d
Using (d _AV ), 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 denotes a motor servo circuit, which converts, for example, the supplied PWM signal into a voltage value (or resistance value), and the converted voltage value (or resistance value) is fed back 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.

Reference numeral 32 denotes a deviation storage unit, which is the deviation calculation unit 22.
The deviation calculated by is stored for the past five times. That is, the current deviation d is set to d ₁ , and the deviations d calculated four times in the past from the deviation d ₁ are held as the deviations d _{2 to} d ₅ .
This holding operation can be realized by, for example, data management by address shift of the memory area or by configuring the deviation storage unit 32 with a shift register.

Reference numeral 33 is an output selection unit, which is a deviation storage unit 32.
Among the deviations d _{1 to} d ₅ stored in (3), three deviations are selected and output excluding the deviation having the maximum value and the deviation having the minimum value. If five deviations are not yet stored in the deviation storage unit 32 when the tape is started, the maximum and minimum determinations are not made, and the accumulated deviations of three or less are output.

Reference numeral 34 is an average value calculation section, which is an output selection section 3
The average value d _AV of the three deviation values supplied from 3 is calculated.

Reference numeral 35 denotes a deviation storage unit 32 and an output selection unit 3
3 shows a controller that controls the operation of the average value calculation unit 34. The writing / reading address is controlled for the deviation storage unit 32, and the newly calculated deviation d is held as the deviation d ₁ , and at the same time, the deviations held as the deviations d ₁ to d ₄ are deviated. It is held by shifting to d _{2 to} d ₅ .

Further, the output selection unit 33 is made to output three deviations excluding the deviations which are usually the maximum and minimum values, and is output when the deviation accumulation number in the deviation storage unit 32 is less than five. Select control. Further, the average value calculation unit 3
For 4, usually, the denominator for calculating the average value is set to 3, and the denominator is set to 1 or 2 according to the number of outputs of the output selection unit when the number of accumulated deviations in the deviation storage unit 32 is less than 5. Take control.

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. And
The deviation d used to calculate the servo control value L _N in the control output calculation unit 25 is the average value d _AV calculated in the average value calculation unit 34, so that a large error in temporary tape running detection due to disturbance or the like may occur. If they do occur, their effects will be cancelled.

The rotation speed servo operation for the reel motor 11 is shown in the flow chart of FIG. That is, when the roller 12a is rotated as the tape travels, the rotary encoder 12 outputs the rotation speed information Sa, and the waveform is shaped and output (Sb), the rotation time measuring unit 21 measures one rotation cycle T of the roller 12a. Will be done (F101). Then, using one rotation cycle T, as described above, the deviation calculator 2
The deviation d is obtained by 2 (F102).

Under the control of the controller 35, the shift of the deviation stored in the deviation storage unit 32 is executed.
That is, the deviation d ₄ is the deviation d ₅ , the deviation d ₃ is the deviation d ₄ , the deviation d ₂ is the deviation d _3, and the deviation d ₁ is the deviation d _2.
It is said that Then, the newly calculated deviation d is taken in as the deviation d ₁ (F103 to F107). Therefore, the deviation d calculated for the past five times including the calculated deviation d is held in the deviation storage unit 32.

The controller 35 discriminates the number of accumulated deviations in the deviation storage unit 32 (F108), and when five deviations are accumulated, the denominator of the calculation formula of the average value calculation unit 34 is set to 3 (F10
9), to output the three deviations except the maximum and minimum deviations from the output selection unit 33 for the deviation d ₁ to d _5.

When the number of accumulated deviations is less than 5 when the tape is started, the denominator for calculating the average value is set according to the accumulated number (F111), and the required deviation is output from the output selection unit 33. . For example, if the stored number is 1, the denominator is 1, and the deviation d ₁ is output. If the stored number is 2, the denominator is 2
Deviations d ₁ and d ₂ are output as
When the denominator is 3, the deviations d ₁ , d ₂ and d ₃ are output, and when the number of accumulations is 4, the denominator is set to 3 and the deviations d ₂ , d ₃ and d ₄ are output.

When the average value d _AV of the deviations supplied by the average value calculation unit 34 is calculated (F113), this is the control output calculation unit 25.
Is supplied to. In the control output calculation unit 25, the average value d of the deviations
_The current servo control value L _N is calculated from _AV , the gain coefficient K, the control constant A, and the previous servo control value L (F114), and is supplied to and stored in the output storage unit 26 (F115). The stored servo control value L is converted into a PWM signal by the data converter 27.
(F116), the motor servo circuit 28 forms the servo output E _M based on the PWM signal, and controls the drive of the reel motor 11 (F117).

By continuing the above operation, the number of rotations of the reel motor 11 is gradually decreased according to the tape traveling position, that is, the winding diameter of the take-up reel 3, and therefore the tape traveling speed is substantially constant. Therefore, the recording medium such as a compact cassette tape used in the recording or reproducing apparatus of the present embodiment is compatible with the recording or reproducing apparatus of the capstan system, and the tape top to the tape end. A faithful recording / reproducing operation is performed without changing the frequency characteristic or the S / N over time.

In addition, since the servo control value L _N is calculated based on the average value excluding the maximum and minimum among the deviations of the past five times, the fluctuation or vibration of the operating voltage, the unevenness of the tape thickness, the wrinkles, etc. occur. Even if a temporary speed (cycle) detection error or the like occurs due to the cycle irregularity of the roller 12a and the deviation d becomes large, the influence thereof does not affect the calculation of the servo control value L _N. Therefore, the servo control is stabilized and the constant speed stability of the tape running is improved.

Furthermore, since the calculation method of various values is a very simple calculation, the above circuit configuration can be easily integrated into an IC using an analog multiplier / divider, or can be easily controlled by a servo using a microcomputer. Can be realized. Further, since the accuracy of the tape running speed controlled by such a servo system is determined by the accuracy of the roller 12a and the rated cycle information T ₀₂₅ which is a reference for calculating the deviation d, the waveform shaping circuit 20 causes the motor to move. The accuracy (for example, temperature characteristic, component characteristic, operating voltage, etc.) in each circuit portion between the servo circuits 28 may be relatively rough, and there is an advantage that it can be realized by a simple and inexpensive circuit.

By the way, although the gain coefficient K is used to calculate the servo control value L _N , the gain coefficient K is set so as to match various operating characteristics of the servo system and the mechanical drive system so that the servo oscillation and the wow / flutter are suppressed. No stable system can be easily realized.

Further, in the embodiment, the tape running speed information is obtained in units of one rotation cycle of the roller 12a. Thereby, the accuracy of the roller 12a (the shaft portion 12a ₁
Even if the eccentricity, the molding error or the mounting error of the light shielding plate 12b, the circularity error of the roller peripheral surface, etc. are slightly bad, these influences are canceled and the tape running speed information (1) is provided with high accuracy. The rotation period T) can be obtained.
Further, the number of output pulses of the rotary encoder is not required to be large by setting one rotation cycle as a unit, and a pulse output of two cycles per rotation is sufficient as in the embodiment. It suffices to obtain a pulse output for one cycle at least once. This makes it possible to reduce the size and cost of the rotary encoder.

Next, a second embodiment of the present invention will be described with reference to FIGS. In FIG. 7, the same parts as those in FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted. In this embodiment, the servo control value L _N is calculated by selectively using the deviation d output from the deviation output unit 22 and the average value d _AV output from the average value calculation unit 34. Therefore, a switching circuit 36 is provided so that the contact SW ₁ is supplied with the output from the average value calculation unit 34 and the contact SW ₂ is supplied with the output from the deviation output unit 22. Then, the switching control of the switching circuit 36 is performed by the controller 35. Further, the denominator of the average value calculation formula in the average value calculation unit 34 is fixed to 3.

That is, in this embodiment, when the accumulated number in the deviation storage unit 32 is less than 5, the deviation d is used as it is. Therefore, the servo operation is as shown in the flowchart of FIG. In addition, steps F201 to F2
The processing of 07 is the same as the processing of steps F101 to F107 in FIG. 2, and the processing of steps F213 to F216 is the same as the processing of steps F114 to F117 in FIG.

At step F208, the controller 35
The number of accumulated deviations in the deviation storage unit 32 is determined, and five pieces are accumulated.
Switch circuit 36 to contact SW₁ Connect to
(F209). And the deviation d₁ ~ D_Five About output selection unit 3
Output 3 deviations except the maximum and minimum deviations from 3.
(F210). Therefore, in the average value calculation unit 34, the average value d _AV
Is calculated (F212), and this is supplied to the control output calculation unit 25.
Be done. In this case, the control output calculator 25 calculates the average deviation value.
d_AV, Gain coefficient K, control constant A, previous servo control value L
To the current servo control value L_N Will be calculated (F
213)

When the deviation accumulation number is less than 5 at the time of starting the tape running, the controller 35 connects the switching circuit 36 to the contact SW ₂ (F211). Therefore, the deviation d output from the deviation calculator 22 is directly supplied to the control output calculator 25. In this case, the control output calculator 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 (F213).

In this embodiment, the same effect as that of the first embodiment can be obtained, and the advantage that the deviation averaging process can be simplified occurs.

In each embodiment, the number of accumulated deviations in the deviation storage unit is not limited to five, and the selected number is not limited to other deviations except maximum and minimum. . In particular, if the number of accumulated deviations is sufficiently large, the effect of a temporary error in speed detection can be canceled even if the average of all accumulated deviations is taken.

The present invention also provides a compact cassette tape, a micro cassette tape, an open reel tape,
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.

[0052]

As described above, according to the present invention, the deviation from the predetermined running speed of the tape-shaped recording medium is calculated from the tape running speed information detected by the tape running speed detecting means, and the deviation of the past n times is calculated. Since the average value of all or all parts is calculated and the servo control value is calculated using this average value, the tape running speed is controlled to be a constant speed, and even for a capstan type recording or reproducing device. Not only the compatibility of recording media and faithful recording / reproducing operation are realized, but also the influence of a temporary error in running speed detection caused by disturbance or unevenness of tape thickness is canceled.
The effect is that stable servo control is realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment.

FIG. 3 is an explanatory diagram of a reel drive structure of the embodiment.

FIG. 4 is an explanatory diagram of a rotary encoder according to an embodiment.

FIG. 5 is an explanatory diagram of a detection operation of the rotary encoder according to the embodiment.

FIG. 6 is an explanatory diagram of output signals of the rotary encoder according to the embodiment.

FIG. 7 is a block diagram of an essential part of a second embodiment of the present invention.

FIG. 8 is a flowchart showing the operation of the second embodiment.

[Explanation of symbols]

 1 Magnetic Tape 3 Take-up Reel 11 Reel Motor 12 Rotary Encoder 12a Roller 12b Shielding Plate 12c Photodiode 12d Phototransistor 20 Waveform Shaping Circuit 21 Rotation Time Measuring Section 22 Deviation Calculating Section 23 Gain Coefficient Generating Section 24 Control Constant Generating Section 25 Control Output Calculation unit 26 Output storage unit 27 Data conversion unit 28 Motor servo circuit 32 Deviation storage unit 33 Output selection unit 34 Average value calculation unit 35 Controller 36 Switching circuit

Claims (2)

[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, tape running speed detection means having a roller that is pressed against the tape-shaped recording medium and rotates as the tape-shaped recording medium runs, and measures the rotation cycle of the roller and uses the measured value. Deviation calculating means for calculating a deviation of the tape-shaped recording medium with respect to a predetermined traveling speed; deviation storing means capable of holding deviations of past n times including the present deviation supplied from the deviation calculating means; Using an average value calculation means for calculating an average value of a part or all of the deviations stored in the storage means and an average value output from the average value calculation means, Based on the servo control value calculation means for calculating a servo control value proportional to the motor rotation speed in the reel drive means, and the traveling speed of the tape-shaped recording medium based on the servo control value calculated by the servo control value calculation means. A recording or reproducing apparatus comprising: a servo unit capable of controlling the number of rotations of the motor in the reel drive unit so as to achieve a predetermined traveling speed. 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, tape running speed detection means having a roller that is pressed against the tape-shaped recording medium and rotates as the tape-shaped recording medium runs, and measures the rotation cycle of the roller and uses the measured value. Deviation calculating means for calculating a deviation of the tape-shaped recording medium with respect to a predetermined traveling speed; deviation storing means capable of holding deviations of past n times including the present deviation supplied from the deviation calculating means; An average value calculation means for calculating an average value of some or all of the deviations stored in the storage means; an average value output from the average value calculation means; Switching means for selectively outputting the calculated deviation to the outputting means, switching control means for controlling the switching of the switching means according to the number of deviations stored in the deviation storage means, and via the switching means Based on the servo control value calculation means for calculating the servo control value proportional to the motor rotation speed in the reel drive means using the supplied average value or deviation, and the servo control value calculated by the servo control value calculation means A servo means capable of 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 the predetermined traveling speed. Playback device.