JPH0348748Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cassette tape recorder, and in particular, to a cassette tape recorder which aims to improve wow and flutter by reducing the tape tension on the exit side of a tape clamping drive unit consisting of a pinch roller and a capstan. The purpose is to provide.

In general, in a cassette tape recorder, the tape is gripped and driven by a gripper drive unit consisting of a pinch roller and a capstan, and the tape is fed out from the gripper drive unit and wound onto a tape winding body on the winding side. The tape winding torque of the tape winding body on the winding side is the torque necessary to overcome the sheet load in the cassette and reliably wind the tape. When the tape is being wound, a tension of about 30gr is generated in the tape being wound. In addition,
The inventor conducted an experiment to investigate the effect of tape tension on ivy and found that when the tape tension exceeds approximately 30gr, slipping occurs in the clamping drive unit consisting of a pinch roller and a capstan, and the tape running speed increases. It has been found that a tape tension that changes in direction, that is, exceeds 30 gr, passes through the clamping drive section and affects the tape running downstream from it, that is, wow and flutter.

On the other hand, there are currently cassette tape recorders that employ a so-called direct drive system in which the rotation of the reel motor is transmitted to the reel shaft without going through the slip mechanism to drive the reel shaft. In this cassette tape recorder, when the torque of the reel motor fluctuates due to cogging, etc., this torque fluctuation is directly transmitted to the reel shaft, and the tension of the tape being wound is changed as shown by graph line I in Figure 3. It will fluctuate. In some cases, the fluctuation range is about 20gr. When the tape tension changes like this,
Tension fluctuations exceeding 30gr affected tape running downstream of the clamping drive section, causing deterioration of wow and flutter characteristics.

The object of the present invention is to provide a cassette tape recorder that solves the above problems, and one embodiment thereof will be described below with reference to the drawings.

FIG. 1 is a schematic plan view of an embodiment of a cassette tape recorder 1 according to the present invention.

The cassette 2 is fitted onto a supply reel shaft 3 and a take-up reel shaft 4. In the recording or reproducing mode, the magnetic tape 5 is held and driven by the pinch roller 6 and the capstan 7, is pulled out from the supply side tape roll 8, and runs adjacent to the erasing head 9 and then to the recording/reproducing head 10. The take-up reel shaft 4 is rotated by a reel motor 11 via a motor pulley 12 and an idler 13 in the tape winding direction shown by arrow A.
The magnetic tape 5a sent out from the tape guide member 1, which is a main part of the present invention, is placed in the capstan chamber 19.
After being guided by 5, the tape is wound onto a winding-side tape winding body 16. Note that the rotation transmission system from the reel motor 11 to the reel shaft 4 is not provided with a slip mechanism, a torque limiter mechanism, etc., and the reel shaft 4 is directly driven by the reel motor 11.

Next, the tape guide member 15 will be explained with reference to FIG. 2.

The tape guide member 15 is a resin molded product, and is attached to the pinch roller support arm 17.
The tape guide portion 15a having a rounded tip enters into the capstan chamber 19 through the pinch roller insertion window 18 of the cassette 2 together with the pinch roller 6, and is located downstream of the upper clamp drive portion 14 in the tape running direction. It comes into contact with the tape 5a, pushes it in and guides it.

The capstan chamber 19 has a capstan insertion hole 1.
Rear wall 19b and left and right side walls 1 surrounding 9a
9c, 19d and front side pinch roller insertion window 1
8.

Therefore, the magnetic tape 5a sent out from the clamp drive unit 14 wraps around the tape guide portion 15a of the tape guide member 15, then around the tape guide portion 19d _-1 of the side wall 19d, and is bent inside the capstan chamber 19. It is considered a tape pass.

Here, the tension T ₁ of the tape on the downstream side of the tape guide part 19 _d-1 , the guide part 19 _d-1 and the guide part 15
Tension T ₂ of the tape between a and guide part 15
Tension of the tape between a and the clamping drive unit 14
The relationship of T ₃ is generally expressed by the following equation (Euler's equation).

T ₁ = T ₂ ×e〓 ¹ 〓 ¹ T ₂ = T ₃ ×e〓 ² 〓 ² , where θ ₁ is _the wrapping angle (50°) of the tape with respect to the guide part 19 _c-1. Wrapping angle with respect to guide part 15a (72°) μ ₁ is the coefficient of friction between the base surface of the tape and guide part 19 _c-1 (0.325) μ ₂ is the friction between the magnetic surface of the tape and guide part 15 a The coefficient is (0.51).

Tension T ₁ is 40gr, tension T ₂ ,
When T ₃ is calculated, T ₂ = 30.12gr T ₃ = 15.87gr. That is, the tape tension is lowered in stages, and the tape tension on the exit side of the clamping drive unit 14 is lowered.
T ₃ is less than 1/2 of the tape tension T ₁ on the take-up side tape winding body 16 side.

When the torque of the reel motor 11 fluctuates due to cogging or the like, this torque fluctuation is directly transmitted to the winding side reel shaft 4, and the tension _T1 of the tape 5a wound onto the tape winding body 16 fluctuates.
Tape tension T ₁ increases by 10gr for example to 50gr
The calculated tape tension T ₃ is 19.83gr, which is about 4gr lower than the original value.
The increase has been compressed to less than half. The reason why this increase (change) is compressed is that the magnetic tape 5a itself is connected to the tape guide section 19 _d-1 ,
This is because it expands and contracts slightly while being guided by 15a to absorb fluctuations.

Therefore, even if the tape tension T ₁ is 40 gr as shown by the graph line in FIG. 3 and fluctuates within the range of ±10 gr, the tape tension T ₃ on the exit side of the clamping drive unit 14 is 40 gr as shown by the graph line in FIG. As shown by the graph line, it is reduced to 16 gr, and the fluctuation range is also compressed to ±4 gr. Therefore, the tape tension
T ₃ is at most 20gr, which is less than the value (30gr) that causes the tape to slip in the clamp drive unit 14, and the effects of tape tension T ₃ and its fluctuations are blocked by the clamp drive unit 14, It does not reach the tape 5b on the side. That is, the magnetic tape 5b on the upstream side of the clamp drive unit 14 runs stably without being affected by the tape tension fluctuation on the take-up tape winding body 16 side, and the wow and flutter characteristics are maintained well without deterioration. be done.

FIGS. 4 and 5 respectively show the state of the modified example of the tape guide member in operation. The tape guide member in each figure is attached to the pinch roller support arm 17 in the same manner as in the above embodiment, and guides the tape so that it enters the capstan chamber 19 and the tape path is bent.

The tape guide member 20 shown in FIG. 4 has an arm part 20a that can be elastically deformed in the middle, and a tape guide part 20b is formed at the tip of the arm part 20a. In a cassette tape recorder incorporating this tape guide member 20, the tape guide part 20b has the function of winding and guiding the tape and lowering the tension on the upstream side, as in the case of the above embodiment. The arm portion 20a is bent in response to the tension fluctuation, and the tape guide portion 20b is displaced in the direction of the arrow, thereby also acting to absorb the tape tension fluctuation. Therefore, in a cassette tape recorder using this tape guide member 20, the influence of fluctuations in the tape tension _T1 on the tape winding body side is better blocked, and the wow and flutter characteristics are maintained well.

The tape guide member 21 shown in FIG.
This configuration is such that the tape guide portion 21a is displaced in the direction of the arrow as the tape guide portion 21a is deformed. The operation and effect of this tape guide member 21 are similar to those of the tape guide member 20 described above, and the explanation thereof will be omitted.

As mentioned above, the cassette tape recorder according to the present invention consists of a capstan and a pinch roller that is in pressure contact with the capstan, and a clamping drive section that is disposed on the downstream side of the upper magnetic head in the running direction of the magnetic tape, and into which the pinch roller is inserted. The pinch roller enters the tape cassette through the pinch roller insertion window of the tape cassette, contacts the magnetic tape that is closer to the tape winding body than the nipping drive unit, and winds the magnetic tape. Since the structure consists of a tape guide member that is attached and guided, the tape tension on the upstream side is reduced by the action of the tape guide member, and the fluctuation range of the tape tension is compressed, so that the winding of the take-up tape is It is possible to effectively prevent the influence of fluctuations in the tape tension on the body side from reaching the part that is attached to the magnetic head on the upstream side through the clamping drive unit, thereby preventing the tape on the tape winding body on the winding side. Good wow and flutter characteristics can be maintained even when the winding torque fluctuates.
In addition, by configuring the tape guide member to be elastically displaceable in response to fluctuations in tape tension, the tape guide member itself has an additional function of absorbing tape tension, and the tape winding body on the winding side is It has the advantage of being effective when applied when the fluctuation range of tape winding torque is large.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an embodiment of the cassette tape recorder according to the present invention, FIG. 2 is an enlarged view showing the interior state of the capstan chamber in FIG. 1 due to the tape guide member for the magnetic tape, and FIG. The figure shows the corresponding variation states of the tape tensions T ₁ and T ₃ in Fig. 2, and Figs. 4 and 5 show the states in which the tape is guided by modified examples of the tape guide member, respectively. It is. DESCRIPTION OF SYMBOLS 1...Cassette tape recorder, 2...Cassette, 3...Supply side reel shaft, 4...Take-up side reel shaft, 5...Magnetic tape, 5a...Magnetic tape downstream from the clamp drive unit, 5b... ...Magnetic tape on the upstream side of the pinch drive unit, 6... Pinch roller, 7...
Capstan, 8... Supply side tape winding body, 9...
...Erase head, 10...Recording/playback head, 11...
...Reel motor, 12...Motor pulley, 13...
... Idler, 14 ... Clamping drive section, 15, 20,
21...Tape guide member, 15a, 20b, 21
a... Tape guide section, 16... Take-up side tape winding body, 17... Pinch roller support arm, 18...
Pinch roller insertion window, 19...capstan chamber,
19a...capstan insertion hole, 19b...rear wall, 19c, 19d...side wall, 19 _d-1 ...tape guide section, 20a...arm section, 22...support stand, 2
3... Leaf spring.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A clamping drive unit consisting of a capstan and a pinch roller in pressure contact with the capstan, and disposed on the downstream side of the magnetic head in the running direction of the magnetic tape, and a tape into which the pinch roller is inserted. The pinch roller enters the tape cassette through the cassette's pinch roller insertion window, contacts the magnetic tape that is closer to the tape winding body than the pinch drive unit, and is near the pinch drive unit, and winds the magnetic tape. A cassette tape recorder comprising a tape guide member that guides the tape. (2) The cassette tape recorder according to claim 1, wherein the tape guide member is configured to be elastically displaceable in response to changes in tape tension.