JPS58118058A - Detector for tape loop position within column - Google Patents

Abstract

PURPOSE:To detect accurately the position of a tape loop, by measuring a change of the electric resistance value of the pressure-sensitive rubber which is pressed by a tape. CONSTITUTION:When the air within a column 11 is adsorbed by a blower, the air existing at the part higher than a tape loop 6 in the column 11 flows once out to a space 17 through a slit 16 and then flows into the lower side of the loop 6 through the slit 16. With such a flow of the air, a ''Mylar '' tape 13 is pressed to a box 12 at the part higher above the loop 6 by the air flowing toward an arrow mark and then pressed to the pressure-sensitive rubber 14 at the part lower than the loop 6 by the air flowing into the slit 16 after going round the back of the tape 13. Therefore the length is varied for the part of the rubber 14 which is pressed by the tape 13 and in response to the position of the loop 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-column tape loop position detection device for a magnetic tape device.

Figure 1 is a front view showing an outline of a conventional magnetic tape device.
In the figure, 1 and 2 are tape reels, 3 is a magnetic head, 4 is a column, and 20 is a magnetic tape. The column 4 serves as an air damper to buffer the tension applied to the magnetic tape 2o when the tape is driven or stopped.
is held in a hanging state in the column 4 as shown in the figure by the negative pressure inside the column 4 generated by suction by the blower 5 and travels. In this case, the detection of the tape loop 6 in the column 4 is carried out by the light emitting elements 7. This was done using a light receiving element 8.

However, in such a conventional method, the light emitting and light receiving elements have a drawback that they are susceptible to dirt, and therefore, it is necessary to periodically clean the light emitting and light receiving elements, which is troublesome.

The present invention is intended to solve the above-mentioned drawbacks, and it is an object of the present invention to provide an in-column tape position detection device that does not require periodic cleaning.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 7.

FIG. 2 is a front view of a column portion to which the present invention is applied, and FIG. 6 is a side view of the same. In the figure, 11 is a column, 12 is a sealing box, 16 is a mylar tape, and 14 is a pressure sensitive rubber.

A slit 16 is formed in the back plate 15 of the column 11 and has a length that exceeds the movement range of the tape loop 6 that extends vertically.

The sealed box 12 has a slit 1 on the outside of the back plate 15.
6 is integrally provided, and a space 17 communicating with the slit 16 is formed inside thereof.

The mylar tape 16 is fixed to the box 12 at both upper and lower ends within the space 17, and has a certain degree of freedom. The width of this Mylar tape 13 is somewhat narrower than the width of the space 17.

The pressure sensitive rubber 14 is attached to the periphery of the slit 16 via an insulator 18 (see FIG. 5) at a portion that contacts the outer space 17 of the column 11.

When the air in the column 11 is sucked by the blower, (3
) The tape loop 6 is located at the position shown in the figure, but since the slit 16 is formed in the column 11 as described above,
The air in the column 11 above the tape loop 6 passes through the slit 16 and exits into the space 17, as shown by the arrow line in FIG. 4, which is an enlarged view of section A in FIG. It flows into the bottom of tape loop B. Due to this air flow, the mylar tape 16 is pressed against the box 12 by the air flowing in the direction of the arrow from the tape loop 6 to -L, as shown in FIG. 5, which is an enlarged view of section B in FIG. The portion below the loop 6 is pressed against the pressure sensitive rubber 14 by the air that once wraps around the back side of the mylar tape 13 and then flows into the slit 16.

Therefore, the length of the portion of the pressure sensitive rubber 14 pressed by the Mylar tape 13 changes depending on the position of the tape loop 6. This relationship is shown in FIG. A solid straight line I shows the relationship between the length L of the portion of the pressure sensitive rubber 14 pressed by the Mylar tape 13 and the height H from the column bottom surface to the tape loop position.

The change in electrical resistance of the pressure-sensitive rubber is shown by the dotted straight line (4), and this value naturally decreases as the deviation increases.As is clear from the distance between cars, the electrical resistance of the pressure-sensitive rubber 14 By measuring the change in resistance value, it is possible to accurately detect the position of the tape loop 6.Moreover, the Mylar tape 16 and pressure sensitive rubber 14 require regular cleaning like conventional light emitting and light receiving elements. This makes maintenance easier.

FIG. 7 is a principle diagram of a circuit that converts a change in pressure-sensitive rubber resistance value into a change in voltage, and the position of the tape loop is determined by the output voltage e.

As described above, according to the present invention, it is possible to simplify maintenance by omitting periodic cleaning that was conventionally required.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an outline of a conventional magnetic tape device, and FIGS. 2 to 7 show an embodiment of an in-column tape loop position detection device according to the present invention. A front view of the applied column part, Fig. 3 is a side view of the same, Fig. 4 is an enlarged view of the main part of Fig. 6, Fig. 5 is an illustration of the action of the microphone-tape, and Fig. 6 is a pressure-sensitive rubber Mylar. A graph showing the relationship between the length of the portion pressed by the tape and the tape loop position, and FIG. 7 is a principle diagram of a circuit that converts changes in the resistance value of the pressure-sensitive rubber into changes in voltage. In the figure, 6 is a tape loop, 11 is a column, 12 is a sealed box, 13 is mylar tape, 14 is a pressure sensitive rubber, 1
5 is a back plate, 16 is a slit, 17 is a space, and 20 is a magnetic tape. Special liver applicant Fujitsu Ltd. agent Patent attorney Gobe Tamamushi (3 others) Figure 2 M3
Figure 4 Figure 7 =333=

Claims (1)

[Claims] In a magnetic tape device comprising a column for buffering tension applied to the magnetic tape when the drive of the magnetic tape is stopped, the column is provided with a slit that extends vertically and has a length that exceeds the moving range of the tape loop, and the slit of the column A sealed box is integrally provided on the outside of the forming part, and a tape having an insulating flexibility of approximately the same length as the slit and narrower than the width inside the box is provided within the box with both upper and lower ends fixed. At the same time, a pressure-sensitive rubber is attached around the slit on the outside of the column in the box while maintaining insulation, and means is further provided for measuring a change in the electrical resistance value of the pressure-sensitive rubber pressed by the tape. An in-column tape loop position detection device characterized by: