JPS61126654A - Reel size detecting system of magnetic tape - Google Patents

Abstract

PURPOSE:To wind a tape with a standard quantity or below, to detect correctly the reel size and to control an ordinary travelling by measuring a tape quantity wound to the reel and a tape tension change at the time of increasing and decreasing the speed of the tape tension change. CONSTITUTION:When a supplying reel 1 accelerates a tape 10 by a full reel in the (a) direction of an arrow, a control device 12 mistakes the reel for a half reel, a driving electric current is supplied to a supplying reel motor 3, and then, a winding reel 2 winds at a prescribed speed regardless of the size of the reel 1 and the tension of the tape 10 is increased. On the other hand, when the tape is accelerated in the (b) direction of an arrow, the tension of the tape 10 is increased, and the phenomenon occurs in the same manner at the time of decelerating. Thus, first, reels 1 and 2 are rotated, a tape travelling distance during the rotation of the reel 1 is measured, the reel size is recognized, and next, the accelerating and decelerating of the prescribed frequency are repeated, the change of the tape tension is executed at a monitoring tension sensor 8. When the change is overshot from the prescribed value, the reel size is increased to one step and a detecting action is completed within the prescribed value.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a reel-to-reel direct drive type magnetic tape device, and particularly to a magnetic tape reel (hereinafter abbreviated as a reel) attached to a magnetic tape device. Regarding size detection.

[Background of the invention]

Reel-to-reel magnetic tape devices are, for example,
As described in Japanese Unexamined Patent Publication No. 52-62004, the drive of the reel motor is controlled according to the amount of tape. but,
In conventional devices of this kind, there are three sizes of reels attached to the device (three types of reels for 2400°, 1200, and 600 feet.Hereinafter, each of the above reels will be referred to as a full reel,
In order to detect whether the reel is a half reel or a quarter reel, the amount of tape wound on the reel was measured. In this case, since no consideration was given to the case where a small amount of tape was wound around a large reel, the size of the reel could be incorrectly detected.

[Purpose of the invention]

An object of the present invention is to provide a method that can correctly detect the size of a reel loaded in a magnetic tape device.

[Summary of the invention]

In a reel-to-reel direct drive type magnetic tape device, the magnetic tape is maintained at a predetermined speed or tension by controlling the drive current according to the load of the reel motor. For this reason, if the size of the loaded reel is erroneously detected, the actual load on the reel motor is different from the value assumed in advance, so normal drive current control cannot be performed, and the tension of the tape fluctuates greatly. Focusing on this point, the present invention attempts to detect the reel size from tape tension fluctuations during drive current control.

[Embodiments of the invention]

FIG. 1 shows a reel-to-reel system which has a guide roller 7, a tension sensor 8, and an information head 9 between a supply reel 1 and a take-up reel 2, and a magnetic tape 10 is directly fed between the two reels. 1 shows a configuration diagram of a reel direct drive magnetic tape device.

The supply reel 1 and take-up reel 2 are supplied with current calculated by a control program 16 stored in a control circuit 12 through a drive circuit 11 in order to maintain the speed and tension of the magnetic tape 10 at predetermined values. It is driven by a supply reel motor 3 and a take-up reel motor 4.

In this embodiment, when applying a certain acceleration to the magnetic tape, the motor drive current is mainly a tape drive current depending on the tape diameter and a reel drive current depending on the reel size, as shown in Figure 2. The drive current is divided into two parts. For example, if we consider the case where a tape wound on a full reel is accelerated in the direction α in Figure 1, as shown in Figure 2, the driving current of the motor is B for the diameter A of the wound tape.
The value of is required. In this case, if the control device incorrectly recognizes the reel size as a half reel, only a value of 0 is given to the drive current. At this time, since the take-up reel 2 is winding up the tape at a predetermined acceleration regardless of the size of the supply reel 1, the tape feed amount of the supply reel 1 becomes less than the specified value, and the supply reel 1 and the take-up 2 reel are The tension in the tape increases between cycles. On the contrary, when the tape is accelerated in the direction shown in Figure 1, the winding of the tape becomes less than the specified value and the tension of the tape decreases.

The above phenomenon also occurs when the tape is decelerated, so
In the present invention, the change in tape tension during acceleration/deceleration operations is detected by the cheek sensor 8, and the reel size is confirmed. FIG. 3 is a flowchart showing the procedure of the above-mentioned detection method. That is, first, the reels 1 and 2 are rotated, and while the tape is running in a predetermined direction, the tape running distance during one rotation of the reel is measured. The measured value corresponds to the circumference of the tape, and the reel size is known from the previously known classification shown in FIG. Next, repeat the acceleration/deceleration a predetermined number of times and monitor the variation in tape tension during that time. If the variation in tape tension deviates from the predetermined value, there may be an error in the initial recognition of the reel size. Decide and set the reel size to 1
Increase the level and repeat the above operation.

As a result, if the tension fluctuation is within a predetermined value, it is determined that the correct reel size has been recognized, and the reel size detection operation is ended. By the way, in the above detection method, the reason why the IJ-le size is increased step by step when tension fluctuation occurs is that it is virtually impossible to wrap tape beyond the diameter of the reel, and the reel size may initially be incorrectly recognized to be larger than the actual size. This is because it is considered impossible to do so. Therefore, even if a full reel is recognized, if a tension fluctuation occurs, another abnormality process is executed as it is caused by a factor other than the erroneous detection of the reel size. According to this embodiment,
Since a hardware reel size detection device is not required, the manufacturing cost of the device can be reduced and reliability can be improved. Furthermore, since it becomes possible to detect the size of a reel wound with less than the standard amount of tape, which is a drawback of the reel size detection method based only on the tape amount, there is an advantage that the restrictions on magnetic tape that can be applied to the device can be significantly relaxed.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, it is possible to accurately recognize the size of a reel of any amount of tape. Even if the reel is wound only partially, the running can be controlled normally.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a reel-to-reel direct drive magnetic tape device, FIG. 2 is a diagram showing the relationship between motor drive current and tape diameter, and FIG. 3 is a flowchart showing the flowchart control procedure of the present invention. FIG. 4 is a diagram for explaining the reel size recognition range based on the amount of tape. 3... Supply reel motor, 4... Take-up reel motor, 11... Drive circuit, 12... Control circuit, 13... Control program. Representative Patent Attorney Akio Takahashi Figure 1 Figure 2 Cow Figure 3

Claims (1)

[Claims] A take-up reel and a supply reel that directly drive the magnetic tape, a take-up reel motor that rotates these reels independently, and means for controlling the drive, and an idler roller that rotates as the magnetic tape moves. In a reel-to-reel direct drive magnetic tape device equipped with a tachometer that generates a pulse at every fixed rotation angle of the idler roller and a tension sensor that detects the tension of the magnetic tape, the tape is wound onto a reel. A reel size detection method characterized in that the size of the supply reel is detected by measuring the amount of cheapness in the supply reel and the variation in tape tension during acceleration and deceleration of the magnetic tape.