Registers – Coded record sensors – Particular sensor structure
Patent
1985-07-02
1988-02-09
Trafton, David L.
Registers
Coded record sensors
Particular sensor structure
235480, 178 95, G06K 710
Patent
active
047243082
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a rewind control unit for a tape reader.
BACKGROUND ART
Conventionally, a tape reader which reads information punched in an NC (Numerical Control) tape or the like is arranged so that, upon receipt of a rewind command, it immediately switches a capstan motor from forward to high-speed reverse rotation to start rewinding of the tape and, upon detection of a rewind stop code by a read element, instantly actuates a brake magnet to stop the tape feed.
With such a method, however, each tension arm moves greatly at the start of rewinding of the tape. Therefore, in order to hold this movement within a permissible range, it is necessary to speed up the response of a reel motor. This necessitates the use with a large motor of a large torque, which, however, causes a large current flow, thereby leading to problems from increased heat generation and increased power dissipation. Further, since it is necessary to halt the tape at the position of the rewind stop code immediately upon its detection, the brake magnet is required to have excellent response. This calls for a large current flow to the brake magnet, and hence also increases heat generation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rewind control unit for a tape reader which permits miniaturization of the reel motor and which consumes less power.
Another object of the present invention is to provide a rewind control unit for a tape reader which ensures that the tape is stopped at the position of a rewind stop code where deceleration of the tape has started, even if the response of the brake magnet is somewhat poor.
The rewind control unit of the present invention is an improved rewind control unit for a tape reader in which a tape paid out from a supply reel and taken up on a take-up reel, is held in a taut condition by means of tension arms. A light source and a read element are each disposed on one side of the tape so that information punched in the tape is read out by the read element. The rewind control unit of the present invention is provided with speed switching means for switching the rotational speed of a capstan motor to a forward low speed, a reverse low speed and a reverse high speed; a decoder for detecting rewind stop codes punched in the tape; counting means for counting the number of rewind stop codes or sprocket signals detected in the time interval between the detection of the first rewind stop code by the decoder and the stopping of the tape feed; and control means which, upon receiving a rewind command, switches the rotational speed of the capstan motor first to the reverse low speed and then to the reverse high speed to rewind the tape and, which, upon detection of the rewind stop code by the decoder, first stops the tape feed by rotating the capstan motor at the reverse low speed, and then driving the capstan motor in the forward direction at the low speed to feed the tape in the forward direction until rewind stop codes or sprocket signals of the number counted by the counting means, are detected.
In response to the rewind command, the rotational speed of the capstan motor is switched from the forward low speed, to the reverse low speed and after the reverse low speed has been reached, a feed magnet is actuated to rewind the tape. As the rewinding of the tape is started, the rotational speed of the capstan motor is gradually increased to the reverse high speed. When a rewind stop code is detected, the rotational speed of the capstan motor is gradually slowed to the reverse low speed. When the reverse low speed is reached, the brake magnet is actuated to stop the tape feed temporarily. A reversible counter stores the number of sprocket signals or rewind stop codes detected from the time when the first rewind stop code is detected to the time when the tape feed is temporarily stopped. After the tape has stopped, the speed of the capstan motor is switched to the forward low speed. When the forward low speed is reached, the feed magnet is actuated to f
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patent: 3569674 (1971-03-01), Becker et al.
patent: 4154396 (1979-05-01), Kirkham
patent: 4237498 (1980-12-01), van Eijck et al.
patent: 4608705 (1986-08-01), Tanaka
Hattori Seiichi
Kanda Kunio
Mizuno Yutaka
Fanuc Ltd.
Trafton David L.
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