JPS6412323B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape length measuring device for a tape winding device, and particularly an object of the present invention is to provide a device that can handle high-speed winding.

In a conventional tape length measuring device, as shown in FIG. 1, a roller 2 that rotates following the movement of a tape 1 is rotatably supported by a rolling ball bearing 3. Reference numeral 4 denotes a light-shielding plate which rotates together with the roller 2. Reference numeral 5 denotes a photo sensor that detects the rotation of the light-shielding plate, and measures the length of the tape by counting signals emitted from the photosensor 5. 6
is a touch roller for increasing the frictional force between the tape 1 and the roller 2 and improving the ability of the roller 2 to follow the tape 1. The touch roller is rotatably supported by a rolling ball bearing 7, and is supported by a lever 8 and a spring 9.
The tape 1 is pressed against the roller 2 with constant pressure.

In such a conventional tape length measuring device, the roller 2 and the touch roller 6 are supported by rolling ball bearings, so when the tape is wound at high speed, it follows the tape due to the frictional resistance of the rolling ball bearings. The disadvantage is that the tape length cannot be measured accurately due to slipping between the tape and the roller.
In addition, both the roller 2 and the touch roller 6,
The moment of inertia of the rolling ball bearing is added, resulting in a considerable moment of inertia as a whole, so if the winding speed is suddenly increased or decreased in order to wind the tape at high speed, the rollers will It has the disadvantage that it cannot follow the movement and slips, making it difficult to accurately measure the length of the tape. Furthermore, in conventional tape length measuring devices, both sides of the tape come into contact with the rollers, so the above-mentioned slippage between the tape and the rollers or the compressive force applied by the touch rollers may cause problems such as in video tapes, etc. The magnetic tape had the disadvantage that the magnetic surface was damaged.

The present invention eliminates the drawbacks of conventional tape length measuring devices, and one embodiment of the present invention will be described below with reference to FIG.

In Fig. 2, 10 is a tape, 11 is a roller that makes up the outer ring of the hydrostatic air bearing and rotates following the tape, and 12 is a shaft that makes up the inner ring of the hydrostatic air bearing, which is hollow inside. This hollow space is connected to an external source of compressed air. 1
Reference numeral 3 designates twelve orifices provided on the circumference of the shaft 12, through which compressed air is supplied from the hollow space of the shaft 12 to the hydrostatic air bearing. 14 is an air nozzle for spraying compressed air onto the tape 10;
The pressure of the compressed air blown out from this nozzle increases the frictional force between the tape 10 and the roller 11, thereby improving the ability of the roller 11 to follow the tape 10. Reference numeral 15 denotes a light-shielding plate that rotates together with the roller 11, and 16 a photo sensor that detects the rotation of the light-shielding plate 15. The length of the tape is measured by counting the signals emitted from this photo sensor.

Due to the above configuration, even when the tape is being wound at high speed or when the tape winding speed changes suddenly, the roller can reliably follow the tape, and the surface of the tape in contact with the roller is only one side. This has the advantage that the length can be measured without damaging the magnetic surface of a magnetic tape such as a video tape.

In this way, the tape length measuring device according to the present invention
Compared to conventional tape length measuring devices, even when the tape is wound at high speed or the tape winding speed changes rapidly, it can accurately measure the tape length with almost no slippage between the tape and the roller. It also has great industrial value because it can measure the length of a magnetic tape such as a videotape without damaging the magnetic surface of the tape.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional tape length measuring device;
The figure is a sectional view of a tape length measuring device which is an embodiment of the present invention. 10...Tape, 11...Roller, 12...
Shaft, 13... Orifice, 14... Air nozzle, 15... Light shielding plate, 16... Photo sensor.

Claims (1)

[Claims] 1. A shaft having an orifice for discharging air around its circumference, a roller that is rotatable around the shaft and constitutes a hydrostatic bearing by the orifice, a detection means for detecting the number of rotations of this roller, and a compressor. This tape length measuring device consists of an air nozzle that is biased by air to bring the tape into contact with this roller, and the roller rotates in accordance with the length of the tape.