1. Field of the invention
The present invention relates to rotary magnetic heads utilized in video tape recorders and digital audio recorders, and particularly relates to a method of inspecting the magnetic heads to find whether each of them are properly assembled onto a rotary drum or not.
2. Related art
It is well known that what is called "a double azimuthal head" as shown in FIG. 3(a) is utilized for the rotary drum X of the video tape recorder or the digital audio tape recorder which records and reproduces at a reference speed and at the twice-faster speed, and two pairs of magnetic heads are assembled on the rotary drum in such manner that each head confronts the other in the diametric direction. In FIG. 3(b), a magnetic head A and a magnetic head C are the recording and reproducing heads for the first channel and a magnetic head B and a magnetic head D are the recording and reproducing heads for the second channel.
In a conventional inspection process of the rotary magnetic heads, each of the magnetic heads A through D is judged to be proper or improper by such method as shown in FIG. 5, where a magnetic tape is fed at the reference speed (Step S.sub.a) and, after a reference signal is recorded on the aforenamed magnetic tape by the magnetic head A (Step S.sub.b), the inspection apparatus is set to the reproducing mode to reproduce the reference signal which has been recorded by the aforenamed magnetic head A (Step S.sub.c) to judge whether the recorded signal is higher than the reference level (Step S.sub.d); if it is lower than the reference level, a troubleshooting measure, such as illumination of a warning lamp, is taken (Step S.sub.e).
In the aforenamed way, the aforenamed inspection process is repeated for the magnetic heads B through D till all the magnetic heads are checked whether they meet the reference value.
As FIG. 4 shows, each of the magnetic heads A through D has an azimuthal angle +.theta..sub.1, .theta..sub.2, -.theta..sub.2 or -.theta..sub.1 and, if these magnetic heads A through D are assembled onto a head base 1 shown in FIG. 3(a) in a incorrect way, the expected functions cannot be exercised.
What has been inconvenient with the conventional inspection method as described above is that the magnetic heads A through D are judged only to be good or defective from their respective performance; whether or not the magnetic heads A through D are properly assembled onto the head base 1 is not inspected.