SU72554A1 - Phonogram player - Google Patents

Description

The known devices for reproducing phonograms that allow slow-motion playback with preservation of the recorded audio frequency range do not ensure their correct reception.

Correct reproduction of the upper audio frequency range is achieved in the device being described by using several magnetic heads with a minimum diameter located on opposite sides of the phonogram and rotating in the opposite direction compared to adjacent heads.

FIG. 1 shows a diagram of the simplest version of the proposed device - with two magnetic heads; in fig. 2 - a series of consecutive positions of the magnetic heads during the operation of the device.

The ferromagnetic recording medium 1 (Fig. 1), which carries a magnetic phonogram on itself, during reproduction, goes past two identical reproduction heads 5, which rotate at equal speeds in opposite directions. Each of the heads has a core 2 with a winding 3, the outputs of which through the switch are connected to the input of the reproduction amplifier (not shown in the diagram).

Since the carrier / covers each head 5 at half the circumference, the reading slits 4 reproduce the sound for half a revolution of each head. At any time, the arrangement of the slots is symmetrical with respect to the line A-A, so that the slots reproduce sounds alternately and there are no gaps in the sound.

Slow playback of sound (e.g., speech) requires a slower speed of movement of the medium compared to its speed when recording. If the playback is performed by a fixed head, the frequency of the recording being played will decrease.

No. 72554-2 -

Such a change in the pitch of the sound with a significant slowdown makes speech completely illegible.

To eliminate this, in the device being described, the reproduction is carried out using rotating heads.

The rotation speed for any slow motion of the carrier must be set so that the slit speed relative to the carrier remains the same as during recording.

FIG. 2 depicts the successive positions of the slots of the heads and the carrier during slowed down reproduction of sound.

Denote the tape speed when writing through v. In this case, its playback speed is equal to VsW-Heads rotate against the carrier’s movement with such an angular speed that the circumferential velocity of the slots is also Vaf, and therefore the velocity of the slots relative to the carrier remains the same as during recording, i.e. and.

FIG. 2 the carrier is conventionally divided into segments equal in length to the semicircle described by the reading slit (points /, 2, 3). The initial position is shown in FIG. 2a; at this moment both slots are opposite the beginning of the first track. During the half-turn, slit I will reproduce the segment / -3 (Fig. 2c), at the same time, slit II will perform a single run. During the next half-turn (Fig. 2c), the slit II will repeat the same segment, and the slit I will not be in contact with the carrier at this time. Next, slot I will reproduce the next segment 3-5, and then slot II will repeat it, and so on.

Subject invention

A device for reproducing soundtracks recorded by a magnetic method, using two or more reading slots, operating in turn and providing sound reproduction with a speed lower than the speed of sound recording on a soundtrack, characterized in that, in order to correctly reproduce the upper frequency range by using magnetic heads of the minimum diameter with a reduced number of reading slots; several (two or more) magnetic heads are used, arranged in series and successively one after the other of the direction of movement on the phonogram opposite sides of the latter and rotating in the opposite, compared with predschestvovavshey and subsequent head direction.