JP3439060B2 - Reel stand braking device for magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder and the like, which relates to tape braking at the time of high-speed tape feeding. 2. Description of the Related Art When a tape end is detected from a tape rewinding state and the operation is shifted to a stop operation, or when the operation state is arbitrarily changed, it is necessary to temporarily stop the reel base. In this case, a brake mechanism is provided to stop the reel base instantaneously. [0003] The conventional reel base braking will be described below with reference to the drawings. FIG. 5 is a plan view of a mechanism of a conventional magnetic recording / reproducing apparatus (hereinafter referred to as "VTR") at the time of high-speed rewinding of a tape, FIG. 6 is a plan view of a VTR mechanism of a conventional brake, and FIG. FIG. [0005] As shown in FIG. 5, a cylinder 3 is provided in the chassis 1 behind the cassette 2 mounting position, and a capstan motor 4 is provided to the right of the cylinder 3 and outside the cassette 2 mounting position. 1 is arranged on the back surface. On both sides of the cylinder 3, a pair of leading guide blocks 5 and 6 are provided with guide grooves 7 and 8 from the center of the chassis 1.
The tape 2d of the cassette 2 is pulled out along with and is moved to wind the tape 2d around the cylinder 3. An erasing head 9 for erasing a magnetic signal is provided on the left side of the cylinder 3 on the chassis 1, and a tape 2d is provided below the head.
A fixed guide (1) 10a and a fixed guide (2) 10b are erected on the chassis to guide the guide. Further, between the fixed guides (1) 10a and the fixed guides (2) 10b, a tension pin 11a implanted in the back tension lever 11 urges the tape 2d leftward to keep the tape 2d running stably. It is provided to do so. The back tension lever 11 is rotatably provided on the chassis 1, is urged counterclockwise around a support shaft 11 c by a spring coil 11 b, and is wound around the outer peripheral wall of the S-side reel base 13.
Is pulling. An audio recording / reproducing head assembly 17 for recording and reproducing audio signals and the like is provided on the upper surface of the capstan motor 4 with the chassis 1 interposed therebetween, and a fixed guide (3) for guiding the tape 2d. 10c
Is erected. Below the capstan motor rotation shaft 4a penetrating from the back surface of the chassis 1, a pinch roller 18 is provided at the tip of a pinch lever (not shown) to press the tape 2d against the capstan motor rotation shaft 4a.
It is provided rotatably about the pinch roller shaft 18a. At the right end of the pinch roller 18, a pull-out guide 19 a for pulling out the tape from the cassette is provided at a free end of a pull-out lever 19 pivotally supported by the chassis 1, and pulls out the tape 2 d to a predetermined position. The brake levers 20, 2 to which pads 20a, 21a are adhered, respectively, are located on the sides of the reel bases 13, 14.
1 is rotatably provided, and a protruding shaft 21 b penetrates the chassis 1 from one end of the T-side brake lever 21 with a margin and protrudes downward. Double brake lever 2
A tension spring 27 is stretched between 0 and 21 so that a rotational load is applied to the reel bases 13 and 14 so that the pad 20 is rotated.
a, 21a are on standby to contact the reel bases 13, 14. Below the brake levers 20, 21, an idler unit 22 for transmitting rotational power to both reel stands 13, 14 is provided. The idler unit 22
Has a swing idler 22a and a slip mechanism (not shown). The swing idler 22a includes an S-side relay gear 15 and a T-side reel base 14 meshed with the S-side reel base 13.
An S-side relay gear provided at an intermediate portion between the two reel stands 13 and 14 for selectively rotating between the T-side relay gears 16 meshed with the S-side relay gear 13 for transmitting the power of the capstan motor 4 to the S-side reel stand 13. 15 meshed. The idler unit 22
Are connected to the capstan motor 4 via an annular belt 23. The guide (1) at the top of the cassette 2
2a, (2) 2b, and (3) 2c are guide pins of the cassette body. In the tape rewinding state, as shown in FIG. 5, the driving force of the capstan motor 4 is
The idler unit 22 transmits the driving force directly to the swing idler 22a without going through a slip mechanism.
Are transmitted to the S reel base 13 by the relay gear 15 meshed with the. Therefore, the tape 2d is supplied from the T-side reel base 14 to the pull-out guide 19a of the pull-out lever 19, the fixed guide (3) 10c, and the audio recording / reproducing head assembly 1
7, leading guide block 6, cylinder 3, leading guide block 5, all erase head 9, fixed guide (1) 10
a, the tension pin 11a, and the fixed guide (2) 10b. Next, from the tape rewinding state, the reel bases 13 and 14 are stopped. At the same time as the braking is started, the annular belt 23 and the swing idler 22a are connected via the slip mechanism of the idler unit 22. And at the same time, the protruding shaft 21 of the T brake lever 21
b is released and the brake levers 20 and 21 are pulled by the tension spring 2
With the bias of 7, the reel bases 13 and 14 are respectively brought into contact with each other, and the rotation of the reel bases 13 and 14 is stopped instantaneously. It should be noted that a control mechanism for separately controlling the brake and the slip mechanism is provided. For details of the brake mechanism, refer to JP-A-7-44939. Next, the capstan motor 4 is braked in the reverse direction, and the rotational force in the reverse direction is transmitted to the swing idler 22a via the annular belt 23, and the swing idler 22a, the S-side relay gear 15 and Are disengaged from each other, and are located at the center of both relay gears as shown in FIG. As described above, the operation from the high-speed tape transport operation to the braking is performed according to the procedure shown in FIG.
That is, in the conventional braking, the transmission of the driving force between the idler unit 22 and the swinging idler 22a is performed by the slip mechanism (Step 2) when the braking is started (Step 1). 20,
When both pads 20a and 21a of 21 are brought into contact, the brake is operated (step 3), the capstan motor 4 is braked in the reverse direction (step 4), and the stop of the capstan motor 4 is determined (step 3). Step 5), the braking of the capstan motor 4 is released (step 6), and the braking is completed (step 7). In the conventional braking device, the supply reel base is subjected to a strong braking torque of about three to four times that of the take-up side, so that the supply-side reel base is wound on the take-up side reel. It stopped earlier than the table and controlled the tape slack. In this braking device, it is necessary to always stop the supply-side reel base first regardless of the winding diameter of the supply-side and take-up-side tapes. Therefore, the optimum value of the brake torque is small when the winding diameter of the tape on the supply side is small compared with the case where the winding diameter is large. The same brake torque is applied as when the diameter is large. This effect becomes more remarkable as the tape winding speed increases, and when the winding diameter of the tape on the winding side is large (the winding diameter of the tape on the supply side is small), braking is performed from the high-speed tape winding state. When applied, the tape is subjected to a large tension, and in the worst case, the tape may be seriously damaged. In order to avoid this damage to the tape, it is necessary to adjust the brake torque to obtain an optimum state. However, since this braking device has a structure in which a pad of a brake lever is pressed against a reel, there is actually an initial variation or a variation in brake torque due to long-term use. Can not. Therefore, it is difficult to completely avoid tape damage and tape slack. [0017] A tape winding and supply reel base, a brake mechanism for applying a brake to each of the winding and supply reel base, and a drive mechanism for driving the winding and supply reel base. In a reel base braking device of a magnetic recording / reproducing apparatus including a motor and an idler mechanism having a slip mechanism and selectively transmitting a driving force of the motor to one of the winding and supply reel bases, At the time of feeding, the driving force of the motor is directly transmitted to one reel base via the idler mechanism without passing through the slip mechanism, and at the time of tape braking, the driving force of the motor is wound up via the slip mechanism. The brake is transmitted to the reel base and the take-up and supply reel base is braked by the brake mechanism. And an ON / OFF control signal is alternately added to the control signal, and the OFF ratio of the control signal is greatly changed with the passage of time. An embodiment of the present invention will be described. FIG. 1 is a flowchart of the braking process according to the present invention, FIG. 2 is a graph showing a control signal to the capstan motor and a change in the speed of the capstan motor, and FIG.
FIG. 4 is a plan view of the VTR mechanism when the reel base is braked. In the following description, only the changed parts will be described, and the same parts as those in the conventional example will be denoted by the same reference numerals and detailed description thereof will be omitted. As shown in FIG. 3, the S-side brake lever 2
Both pads 20a, 21a of 0 and T side brake lever 21
Is changed to pads 50a and 51a having a smaller braking force than the conventional one. In the present invention, the arrangement of the mechanisms (only the pads are different) is the same as in the prior art. From the high-speed tape rewinding state shown in FIG.
The state of the mechanism during braking is as shown in FIG.
In this case, as described in the conventional example, the annular belt 23 and the swing idler 22a are coupled via the slip mechanism, and the swing idler 22a is in a state of being meshed with the S-side relay gear 15. Next, the protruding shaft 21b of the T brake lever 21 is disengaged, and the brake levers 20, 21 start to abut on the reel bases 13, 14, respectively, by the urging of the tension spring 27.
Up to this point, it is the same as the conventional example. In the conventional example, the brake levers 20, 2
1, a reverse voltage was applied to the capstan motor 4 to stop the capstan motor 4 instantaneously, but the present invention does not apply a reverse voltage to the capstan motor 4 but turns on in the forward voltage direction. By applying a / OFF control signal, the capstan motor 4 is decelerated while the tape 2d is slackened, and the ON / OFF time ratio (duty ratio) is changed to slow down the deceleration. Therefore, the turning power by ON / OFF of the capstan motor 4 is transmitted to the S-side reel base 13 via the slip mechanism and the swing idler 22a. The control signal for decelerating the capstan motor 4 has a duty ratio ON: 80% in the initial stage,
A signal of OFF: 20% is applied for three cycles, and a signal of duty ratio ON: 50%, OFF: 50% is applied for three cycles. Brake lever 2 to reel stands 13 and 14
The brakes 0 and 21 start to operate when the ON / OFF control signal is applied for one or two cycles. Since the pads 50a and 51a of the brake levers 20 and 21 have a smaller braking force than the conventional one, the reel base does not stop immediately unlike the conventional one. Therefore, the braking force by the brake and the rotating power transmitted from the capstan motor 4 via the slip mechanism are applied to the S-side reel base 13.
Since the braking force on the S-side reel base 13 is usually quite low, if the influence of the T-side reel base 14 is not considered,
The torque obtained by subtracting the S-side brake torque from the winding torque via the slip mechanism is applied to the S-side reel base 13 in the winding direction. As a result, even if the braking of the T-side reel base 14 is delayed during braking, the rotation of the S-side reel base 13 causes the tape 2 to rotate.
It becomes possible to take up d and prevent tape slack from occurring. Conversely, when the braking of the T-side reel base 14 is fast, the winding torque of the S-side reel base 13 is smaller than the braking torque of the T-side reel base 14, so that the rotation is consumed by the slip mechanism and the tape 2d is wound. Not taken. still,
At this time, the winding torque of the S-side reel base 13 is considerably canceled even by the brake torque of the S-side reel base 13, and as a result, the tension (tension) applied to the tape 2d is reduced. When the capstan motor 4 is stopped, the brake is applied to the T-side reel base 14 and the ON / OFF control signal is applied to the capstan motor 4 at a stage where the rotation speed is reduced to a level at which the tape does not become loose. Is stopped and normal braking is performed. Normal braking is performed by applying a voltage in the reverse direction, and by detecting the number of rotations of the capstan motor 4, the stop is confirmed and braking is terminated. FIG. 2 shows a specific relationship between the capstan motor voltage and the capstan motor rotation speed in this embodiment. In the section A, the tape is fast rewound, and the rotation speed of the capstan motor is 2500 rpm. Section B is a braking section in which a control signal with a duty ratio of ON: 80% and OFF: 20% is applied for three periods. From the center of the section B, braking by the brake levers 20 and 21 starts to be applied. After the center of the section B, the braking force by the brake and the capstan motor 4 are applied to the S-side reel base 13 via the slip mechanism. The transmitted turning power is applied. In section C, the duty ratio is ON: 50%, OFF: 50%
Is applied for three cycles to slow down the deceleration operation. When the tape is loosened in the sections B and C, the tape is not damaged and the tape is slackened. In the section D, the motor speed is 1800 rpm
After confirming that the speed has been reduced to m, the braking of the capstan motor 4 in the reverse rotation direction is started until the capstan motor is completely stopped. Section E is the end of braking. In the present embodiment, the rotation speed at which there is no fear of tape slack is 1800 rpm as shown in the figure. FIG. 1 is a flowchart showing the contents of the above-described braking device of the present invention. As compared with the conventional braking device (see FIG. 7), steps 1 to 7
Up to the same operation as the conventional example, steps 3 and 4
Step 10 is added during. This step 10 is a portion corresponding to the section B and the section C in FIG. 2, and applies an ON / OFF signal to the capstan motor.
This is a step for changing the ON / OFF duty ratio, gently decelerating the reel bases 13 and 14 while removing tape slack without causing tape damage. In the drawings, only the tape rewinding braking is shown, but it goes without saying that the reel stand braking device of the present invention can be used for tape fast-forwarding and also when the tape is not pulled out. In the present embodiment, the motor is provided with an ON / OFF control signal.
This corresponds to braking the motor once. This is to ensure the switching of the slip mechanism by braking the motor. Decreasing the torque corresponds to reducing the torque of the motor by giving an ON / OFF signal instead of giving a continuous signal to the motor. According to the present invention, tape slack and tape damage can be suppressed even if the brake torque applied to the take-up and supply reels fluctuates to some extent, so that high-speed tape transport in a magnetic recording / reproducing apparatus becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart of braking according to the present invention. FIG. 2 is a graph showing a control signal to the capstan motor and a change in the speed of the capstan motor according to the present invention. FIG. 3 is a plan view of a VTR mechanism at the time of high-speed tape rewinding of the present invention. FIG. 4 is a plan view of a VTR mechanism during braking of a reel base according to the present invention. FIG. 5 is a plan view of a VTR mechanism at the time of high-speed rewinding of a tape base according to a conventional example. FIG. 6 is a plan view of a mechanism of a VTR at the time of braking of a reel base according to a conventional example. FIG. 7 is a flowchart of a conventional braking process. [Explanation of Signs] 2d Tape 4 Capstan motor 13 S-side reel stand 14 T-side reel stand 20 S side Brake lever 21 T-side brake lever 22 Idler unit 22a Swing idler 23 Annular belt 27 Tension spring 50a S Side pad 51a T side pad Step 1 Brake start step 2 Switch to slip mechanism Step 3 Brake operation Step 4 Brake step 5 of reverse voltage to capstan motor Step 5 Stop capstan motor Confirmation step 6: Capstan motor braking release step 7: Braking end step 10: ON / OFF signal applied to capstan motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 15/18 G11B 15/22 G11B 15/44

Claims (1)

(57) [Claim 1] A tape take-up and supply reel base, a brake mechanism for applying a brake to each of the take-up and supply reel base, and a drive mechanism for driving the take-up and supply reel base A motor for selectively driving the driving force of the motor to one of the winding and supply reel table, and a reel table braking device of a magnetic recording and reproducing apparatus including an idler mechanism having a slip mechanism. At the time of high-speed feeding of the tape, the driving force of the motor is directly transmitted to one of the reel tables via the idler mechanism without passing through the slip mechanism, and at the time of tape braking, the driving force of the motor is transmitted through the slip mechanism. The brake mechanism transmits a brake to the take-up / supply reel table and transmits the signal to the take-up reel table. / OFF reel stand brake apparatus characterized by significantly changing over time the ratio of OFF of the control signal with added alternately control signal.