In a magnetic recording and reproducing device such as a tape recorder or a video tape recorder, a magnetic tape is run to be in sliding contact with a magnetic head so as to convert an electric signal to a magnetic signal or a magnetic signal to an electric signal.
However, if a magnetic recording and reproducing device such as mentioned above is continued to be utilized, foreign substances adhere to a sliding surface of the magnetic head, and decrease of reproduced signals occurs by the adhesion layer. The adhering foreign substances are a whited substance generated in accordance with sliding between the magnetic head and the magnetic tape, and are regarded as being mainly composed of oxides produced by adhesion and oxidation of silicone, which is present in a slight amount in air, by frictional heat at the time of sliding or by minute energy of static electricity.
Conventionally, such adhesion of foreign substances was not so large a problem; however, in recent years, according as the signal of the magnetic recording and reproducing device changes from analog to digital, or according as the recording density of the magnetic tape increases, the design precision of the magnetic head or the like is becoming severer, so that even if a minute foreign substance adheres to the magnetic head, it will have a large influence on the reading precision of the magnetic data.
Particularly, if a metal vapor deposition tape capable of high-density recording is used as the magnetic tape, the adhesion of foreign substances to the magnetic head will be much, and often has an influence on the data reading precision. This seems to be due to the fact that, since the magnetic head and the metal vapor deposition tape are both made of metal materials, the heat generated by friction is large, and the amount of generated oxide is large. For this reason, prevention or reduction of adhesion of foreign substances to the magnetic head is an objective to be achieved.
Restraint of the adhesion of oxides is disclosed also in Publication of Unexamined Japanese Patent Application No. 5-86005; however, the oxides herein referred to are a blacked substance produced by oxidation of an organic substance being present in air and having an unsaturated bond by an extremely large energy such as a spark at an electric contact point between a brush and a commutator, and degrade the electrical conduction state of the electric contact point. As compared with this blacked substance, the aforesaid whited substance is extremely smaller, and does not have a large influence on the electrical conductivity even if it is generated at the electric contact point, so that the problem caused by the whited substance is different from that caused by the blacked substance.
The object of the present invention is to provide a magnetic recording and reproducing device that can restrain the adhesion of foreign substances to the magnetic head.