JPH0135307Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape tension detection device suitable for use in a VTR, audio tape recorder, or the like.

Conventionally, as this type of tape tension detection device, a so-called cantilever method or an arm rotation method is known. However, when looking at the vibration system for tension detection, the rigidity of each cantilever or arm, the rotational moment in the case of an arm rotation method, the mass of the cantilever in the case of a cantilever method, and the detection frequency characteristics. The balance between the two has become an issue.

That is, in order to extend the frequency characteristics, it is necessary to increase the rigidity of these components and keep the rotational moment, mass, etc. small. However, when actually manufacturing a detection device, these relationships often have contradictory configurations, so it is currently difficult to dramatically improve such frequency characteristics. It was hot. In addition, in each conventional detection method, the tension is detected by the so-called wrap angle, so a tape guide post is required. However, it also had the drawback of adversely affecting tape running.

The present invention was developed in order to avoid the above-mentioned drawbacks, and it is designed to reduce the mass of the tension detection member and reduce the wrap angle so as not to excite tape vibration. It is something.

An example of the apparatus according to the present invention will be described below with reference to the drawings.

That is, in the present invention, a fixing member 1 is provided, a cavity 2 is formed in a part thereof, this cavity 2 is closed with a diaphragm 3 and a semiconductor element 4, and gas or liquid 5 is injected into the cavity 2. It is enclosed. In the case of liquid, silicone oil can be used. As the semiconductor element 4, one whose electrical characteristics, for example, the amount of current, change depending on the pressure is used.

In the example shown in the drawings, the fixing member 1 is sandwiched between a front cover 7 and a rear cover 8 from the front and rear, and is configured to have a cylindrical shape as a whole. The semiconductor element 4 is bonded to the rear surface of the fixing member 1 with an adhesive, and a cavity 2b is formed between the semiconductor element 4 and the fixing member 1;
Cavity 2 formed by the above-mentioned diaphragm
This figure shows a case in which the empty chamber 2 is configured by connecting the space 2 and the space 2 with a conductive path 2c.

Further, in the present invention, a contact member 6 is provided on the front surface of the diaphragm 3, and the front surface is formed on the contact surface 10 of the tape 9. In this case, the contact surface 10 is formed to form a part of a cylindrical surface, that is, a cylindrical surface formed by the fixing member 1 and the front and rear covers 7 and 8.

The operation of such a configuration will be explained. Assuming that the tape 9 now travels in the direction of the arrow, based on this, pressure is applied to the contact member 6 by a composite vector as shown in the vector diagram shown in FIG. This pressure pushes the diaphragm 3, and as a result, the silicone oil 5 in the cavity 2 influences the semiconductor element 4, changing its electrical characteristics, that is, the amount of current. Therefore, the magnitude of the pressure based on this composite vector is detected by the semiconductor element 4. It should be noted that a so-called feedback system that constantly maintains the tape tension substantially constant based on this detection output is well known in the art, and will therefore be omitted in this example.

Therefore, according to the present invention, it is possible to omit arms and tape guide posts, which have a relatively large mass, as in conventional cantilevers. Therefore, when viewed from the vibration system, the mass can be made extremely small, that is, problems with frequency characteristics can be eliminated, and high frequency response is possible. This point is extremely advantageous for detecting vibrations in the longitudinal direction of the tape as the tape runs.

Furthermore, according to the present invention, changes in tape tension are detected by the semiconductor element 4 as pressure changes via the silicone oil, so vibrations from the outside are less likely to be transmitted, and therefore a sufficient high frequency response can be generated. It has some characteristics. In other words, when trying to obtain a high frequency response with conventional equipment, it is difficult to distinguish between actual changes in tape tension and changes due to external vibrations, and it is difficult to obtain a good S/N ratio. However, the present invention has the feature that this problem can also be solved.

The contact member 6 according to the invention can also be used, for example, with an erasing head. In other words, it is possible to use both the erasing head and the tape contacting member 6. In addition to the erasing head, for example, in a magnetic recording/reproducing apparatus, any fixed head used therein may also be used.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of the device according to the present invention, and FIG. 2 is a vector diagram thereof. 1 is a fixing member, 6 is a contact member, 2 is an empty chamber, 3 is a diaphragm, 4 is a semiconductor element, and 9 is a tape.

Claims (1)

[Scope of utility model registration request] A cavity formed in a part of the fixing member is closed by a diaphragm and a semiconductor element, and the pressure applied to the diaphragm is detected by the semiconductor element through liquid or gas sealed in the cavity. A tape tension detection device characterized in that a detection body is provided, a contact member that contacts the tape is attached to the front surface of the diaphragm, and a contact surface of the contact member with the tape is a curved surface forming a part of a cylindrical surface. .