JPH06111426A - Tape tension controller - Google Patents

Abstract

PURPOSE:To improve the envelope of a video signal, etc., by detecting and controlling directly tape tension in the position of a rotary head. CONSTITUTION:In a rotary head type magnetic recording and/or reproducing device, this tape tension controller consists of the detection means of a piezoelectric element 6, etc., detecting the tape tension in a rotary head drum 5 and a means controlling the tape tension based on the detected value. The detected tape tension is converted to voltage and compared with a reference value, and the compared result is sent to the controller. By the controller, the positions of variable control pins 7, 8 provided on the inlet side and/or the exit side of the rotary head drum are moved, or the speed of a variable speed roller coming into contact with a running tape is increased/decreased, and the contact pressure of the tape applied to the rotary head drum is adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type magnetic recording and / or reproducing apparatus for controlling tape tension. More specifically, the present invention relates to a device for controlling the tape tension on the rotary head drum of a VCR constantly.

[0002]

2. Description of the Related Art In a video tape recorder (VTR), the contact portion between the rotary head and the tape is relatively long,
Also, the tape expands and contracts due to the frictional resistance caused by the contact with the guide posts and the like. A tape tension servo mechanism is used in order to reduce the fluctuation of the video signal due to this and stabilize the contact between the rotary head and the tape. As an example thereof, there is a band brake type tension servo mechanism, in which the tightening force of the band brake for the supply reel is changed according to the tape tension applied to the tension arm. Further, as an example of the electronic tension servo, there is one that converts a change in tension detected by the tension arm into a voltage and brakes the supply reel so that this voltage becomes constant.

[0003]

In the tape tension of the VTR, the value at the entrance of the rotary head drum is standardized in each format. For example, the back tension of the tape is 30 to 45 g in the VHS method and 45 in the beta method.
± 5 g. The above-described conventional tension servo mechanisms all control the tape tension to maintain these values. However, it is desirable to directly control the tape tension in the rotary head drum in order to better record and read the video signal and improve the image quality of the video tape.

[0004]

According to the present invention, in a rotary head type magnetic recording and / or reproducing apparatus, means for detecting tape tension in the rotary head drum,
There is provided a tape tension control device comprising means for controlling the tape tension based on the detected value.
A typical example of the rotary head type magnetic recording and / or reproducing apparatus is a VTR, but the principle of the present invention described below is not limited to the VTR, and a tape is recorded by using a rotary magnetic head such as a video camera. Any device that performs recording / reproduction can be applied.

The means for detecting tape tension in the rotary head drum is preferably a piezoelectric element provided in the rotary head drum. As is well known, a piezoelectric element is an element that converts strain caused by mechanical pressure into voltage. By embedding this in the surface of the rotary head drum at the tape running position so as to receive the pressure of the tape, the tape tension can be detected and output as a voltage value. Piezoelectric ceramics,
Crystals, barium titanate, etc. are available and are not particularly limited. The piezoelectric element may be provided on either the upper drum or the lower drum of the rotary head drum. The size and number of the piezoelectric elements are not limited, but it is preferable that the piezoelectric elements are uniformly provided around the periphery of the rotary head drum, and usually, the number is appropriately selected and used within the range of 5 to 30.

The means for controlling the tape tension may utilize a conventional tension servo mechanism, and may be configured to brake the supply reel in accordance with the detected voltage value of the tape tension. However, in addition to the conventional tension servo mechanism, it is preferable to provide a movable control pin on the inlet side and / or the outlet side of the rotary head drum in order to perform more delicate control of the tape tension. Alternatively, the rotational speed of the roller contacting the running tape can be controlled to control the tape tension to a desired value. The control can be performed, for example, by comparing the detected tape tension voltage with a reference voltage, and moving the position of the control pin based on the result, or adjusting the tension by increasing or decreasing the rotation speed of the roller.
This control can be easily performed by applying the control method used in the normal feedback control system.

[0007]

FIG. 1 shows an embodiment of the present invention. In this embodiment, the present invention is shown as being applied to an M loading type VTR, but it is needless to say that the present invention is also applicable to the U loading type VTR shown in FIG. 2 and others.

In the tension control device 1, a large number of piezoelectric elements 6 made of piezoelectric ceramic are embedded on the peripheral surface of a rotary head drum 5 composed of an upper drum 3 rotating with the magnetic head 2 and a fixed lower drum 4. . Inclined guides 7 and 8 are provided on the inlet side and the outlet side of the rotary head drum 5, and the tape 9 is wound around the rotary head drum 5 at an angle. According to the invention,
The tilt guides 7 and 8 are simultaneously configured as tension control pins, and are movable in the directions of arrows A and B by a mechanism (not shown). Of course, other pins such as the guide pins 10 and 11 can be configured as the tension control pin, and the tension arm 12 can be used as the tension control pin at the same time.

FIG. 2 shows another embodiment of the present invention applied to a U-loading type VTR. The same reference numerals as those in FIG. 1 indicate members having the same function. In the embodiment shown in FIG. 2, the roller 13 is constructed so as to have a variable rotational speed, and the tape tension to the rotary head drum 5 is increased or decreased by increasing or decreasing the speed when the tape 9 traveling between the roller 14 and the pin 14 is contacted. Is adjustable.

FIG. 3 is a block diagram of an example of a control system that can be used for the control of the present invention. The pressure of the piezoelectric element 6 provided on the surface of the rotary head drum 5 is detected by the detection circuit 21 and sent to the comparator 22. A reference voltage is applied from the reference voltage circuit 23 to the comparator 22. This reference voltage is used for the piezoelectric element 6 when the SXG tape of Fuji Photo Film Co., Ltd. is run, for example.
Is the value detected by. Alternatively, it may be a value that can be adjusted manually or automatically as appropriate. When the adjustment is not performed, the reference value may be stored in the comparator 22 in advance. The output from the comparator 22 is the controller 2
4 is transmitted. The controller 24 controls the position of the tension control pin and the speed of the rotating roller by using an appropriate mechanism (not shown).

[0011]

The operation of the present invention will be described with reference to FIGS. When the tape is run on a VTR incorporating the tension control device 1 of FIG. 1, the tape tension is detected by the piezoelectric element 6. The detected tension is converted into a voltage in the detector 21 and sent to the comparator 22. It should be noted that this detection can be performed by various methods such as summing or averaging the voltage values of several piezoelectric elements located at the positions in contact with the tape, and sampling the piezoelectric elements located at appropriate positions as appropriate. it can. The detected voltage value is compared with the reference voltage from the reference voltage circuit 23,
The result is output to the controller 24. Based on the applied output, the controller 24 causes the tilt guides 7, 8 to
Adjust the position of to change the tape tension. The result is fed back to the circuit of FIG. 3, thus controlling the tension to a value corresponding to the desired reference voltage.

[0012]

According to the present invention, the tape tension in the head can be directly detected and controlled to the optimum value by using the detecting means such as the piezoelectric element provided on the rotary head drum. There is a method of analyzing the envelope of a video signal as one method of measuring the quality of image quality of a video tape or the like, but according to the knowledge of the present inventors, generally, when the tape tension is strong, the front part of the envelope occurs. If it is weak, back chipping will occur. When the tension control device according to the invention of the present application is used, a clean envelope having no front and rear defects can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a tension control device of the present invention.

FIG. 2 is a perspective view showing another embodiment of the tension control device of the present invention.

FIG. 3 is a block diagram of an example of a control system used in the tension control device of the present invention.

[Explanation of symbols]

 1 Tension control device 2 Magnetic head 5 Rotating head drum 6 Piezoelectric element 7,8 Inclination guide 13 Roller 21 Detection circuit 22 Comparator 23 Reference voltage circuit 24 Controller

Claims (4)

[Claims] 1. A rotary head type magnetic recording and / or reproducing apparatus comprising: means for detecting tape tension on the rotary head drum; and means for controlling tape tension based on the detected value. Tape tension controller. 2. The tape tension control device according to claim 1, wherein the means for detecting the tape tension is a piezoelectric element provided on the rotary head drum. 3. The tape tension control device according to claim 1, wherein the means for controlling the tape tension includes a movable control pin provided on an inlet side and / or an outlet side of the rotary head drum. 4. The tape tension control device according to claim 1, wherein the means for controlling the tape tension includes a roller having a variable speed.